Fossil

  Blob pathname;
  const char *zPath;

  file_tree_name(zName, &pathname, 1);
  zPath = blob_str(&pathname);
  if( strcmp(zPath, "manifest")==0
   || strcmp(zPath, "_FOSSIL_")==0
   || strcmp(zPath, "_FOSSIL_-journal")==0
   || strcmp(zPath, ".fos")==0
   || strcmp(zPath, ".fos-journal")==0
   || strcmp(zPath, "manifest.uuid")==0
   || blob_compare(&pathname, pOmit)==0
  ){
    fossil_warning("cannot add %s", zPath);
  }else{
    if( !file_is_simple_pathname(zPath) ){
      fossil_fatal("filename contains illegal characters: %s", zPath);

  blob_init(&path, g.zLocalRoot, n-1);
  if( zIgnoreFlag==0 ){
    zIgnoreFlag = db_get("ignore-glob", 0);
  }
  vfile_scan(0, &path, blob_size(&path), allFlag);
  db_prepare(&q, 
      "SELECT x FROM sfile"
      " WHERE x NOT IN ('manifest','manifest.uuid','_FOSSIL_',"
                         "'_FOSSIL_-journal','.fos','.fos-journal')"
      "   AND NOT %s"
      " ORDER BY 1",
      glob_expr("x", zIgnoreFlag)
  );
  if( file_tree_name(g.zRepositoryName, &repo, 0) ){
    db_multi_exec("DELETE FROM sfile WHERE x=%B", &repo);
  }

  db_must_be_within_tree();
  db_multi_exec("CREATE TEMP TABLE sfile(x TEXT PRIMARY KEY)");
  n = strlen(g.zLocalRoot);
  blob_init(&path, g.zLocalRoot, n-1);
  vfile_scan(0, &path, blob_size(&path), dotfilesFlag);
  db_prepare(&q, 
      "SELECT %Q || x FROM sfile"
      " WHERE x NOT IN ('manifest','manifest.uuid','_FOSSIL_',"
                       "'_FOSSIL_-journal','.fos','.fos-journal')"
      " ORDER BY 1", g.zLocalRoot);
  if( file_tree_name(g.zRepositoryName, &repo, 0) ){
    db_multi_exec("DELETE FROM sfile WHERE x=%B", &repo);
  }
  while( db_step(&q)==SQLITE_ROW ){
    if( allFlag ){
      unlink(db_column_text(&q, 0));

    bag_insert(&contentCache.missing, rid);
  }else{
    bag_insert(&contentCache.available, rid);
  }
  return rc;
}































/*
** COMMAND:  artifact
**
** Usage: %fossil artifact ARTIFACT-ID  ?OUTPUT-FILENAME?
**
** Extract an artifact by its SHA1 hash and write the results on
** standard output, or if the optional 4th argument is given, in

  z = vmprintf(zFormat, ap);
  va_end(ap);
  if( g.xferPanic ){
    cgi_reset_content();
    @ error Database\serror:\s%F(z)
    cgi_reply();
  }
  if( g.cgiOutput ){
    g.cgiOutput = 0;
    cgi_printf("<h1>Database Error</h1>\n"
               "<pre>%h</pre><p>%s</p>", z, zRebuildMsg);
    cgi_reply();
  }else{
    fprintf(stderr, "%s: %s\n\n%s", g.argv[0], z, zRebuildMsg);
  }
  db_force_rollback();

}

/*
** Print warnings if a query is inefficient.
*/
static void db_stats(Stmt *pStmt){
#ifdef FOSSIL_DEBUG
  int c1, c2, c3;
  const char *zSql = sqlite3_sql(pStmt->pStmt);
  if( zSql==0 ) return;
  c1 = sqlite3_stmt_status(pStmt->pStmt, SQLITE_STMTSTATUS_FULLSCAN_STEP, 1);
  c2 = sqlite3_stmt_status(pStmt->pStmt, SQLITE_STMTSTATUS_AUTOINDEX, 1);
  c3 = sqlite3_stmt_status(pStmt->pStmt, SQLITE_STMTSTATUS_SORT, 1);
  if( c1>pStmt->nStep*4 && strstr(zSql,"/*scan*/")==0 ){
    fossil_warning("%d scan steps for %d rows in [%s]", c1, pStmt->nStep, zSql);
  }else if( c2 ){
    fossil_warning("%d automatic index rows in [%s]", c2, zSql);
  }else if( c3 && strstr(zSql,"/*sort*/")==0 && strstr(zSql,"/*scan*/")==0 ){
    fossil_warning("sort w/o index in [%s]", zSql);
  }
  pStmt->nStep = 0;
#endif
}

/*

  if( zHome==0 ){
    zHome = getenv("APPDATA");
    if( zHome==0 ){
      zHome = getenv("HOMEPATH");
    }
  }
  if( zHome==0 ){
    fossil_fatal("cannot locate home directory - "
                "please set the HOMEPATH environment variable");
  }
#else
  zHome = getenv("HOME");
  if( zHome==0 ){
    fossil_fatal("cannot locate home directory - "
                 "please set the HOME environment variable");
  }
#endif
  if( file_isdir(zHome)!=1 ){
    fossil_fatal("invalid home directory: %s", zHome);
  }
#ifndef __MINGW32__
  if( access(zHome, W_OK) ){
    fossil_fatal("home directory %s must be writeable", zHome);
  }
#endif
  g.zHome = mprintf("%/", zHome);
#ifdef __MINGW32__
  /* . filenames give some window systems problems and many apps problems */
  zDbName = mprintf("%//_fossil", zHome);
#else

    const char *zBgClr = db_column_text(&q, 8);
    const char *zBr = db_column_text(&q, 9);
    int gidx;
    char zTime[10];
    char zShort[20];
    char zShortCkin[20];
    if( zBr==0 ) zBr = "trunk";
    gidx = graph_add_row(pGraph, frid, fpid>0 ? 1 : 0, &fpid, zBr, zBgClr);
    if( memcmp(zDate, zPrevDate, 10) ){
      sprintf(zPrevDate, "%.10s", zDate);
      @ <tr><td>
      @   <div class="divider"><nobr>%s(zPrevDate)</nobr></div>
      @ </td></tr>
    }
    memcpy(zTime, &zDate[11], 5);

** timeline corresponds to a row in the graph.
*/
struct GraphRow {
  int rid;                    /* The rid for the check-in */
  int nParent;                /* Number of parents */
  int aParent[GR_MAX_PARENT]; /* Array of parents.  0 element is primary .*/
  char *zBranch;              /* Branch name */
  char *zBgClr;               /* Background Color */

  GraphRow *pNext;            /* Next row down in the list of all rows */
  GraphRow *pPrev;            /* Previous row */
  
  int idx;                    /* Row index.  First is 1.  0 used for "none" */
  u8 isLeaf;                  /* True if no direct child nodes */
  u8 isDup;                   /* True if this is duplicate of a prior entry */

  return p->apHash[h];
}

/*
** Return the canonical pointer for a given branch name.
** Multiple calls to this routine with equivalent strings
** will return the same pointer.
**
** Note: also used for background color names.
*/
static char *persistBranchName(GraphContext *p, const char *zBranch){
  int i;
  for(i=0; i<p->nBranch; i++){
    if( strcmp(zBranch, p->azBranch[i])==0 ) return p->azBranch[i];
  }
  p->nBranch++;

** Add a new row t the graph context.  Rows are added from top to bottom.
*/
int graph_add_row(
  GraphContext *p,     /* The context to which the row is added */
  int rid,             /* RID for the check-in */
  int nParent,         /* Number of parents */
  int *aParent,        /* Array of parents */
  const char *zBranch, /* Branch for this check-in */
  const char *zBgClr   /* Background color. NULL or "" for white. */
){
  GraphRow *pRow;

  if( p->nErr ) return 0;
  if( nParent>GR_MAX_PARENT ){ p->nErr++; return 0; }
  pRow = (GraphRow*)safeMalloc( sizeof(GraphRow) );
  pRow->rid = rid;
  pRow->nParent = nParent;
  pRow->zBranch = persistBranchName(p, zBranch);
  if( zBgClr==0 || zBgClr[0]==0 ) zBgClr = "white";
  pRow->zBgClr = persistBranchName(p, zBgClr);
  memcpy(pRow->aParent, aParent, sizeof(aParent[0])*nParent);
  if( p->pFirst==0 ){
    p->pFirst = pRow;
  }else{
    p->pLast->pNext = pRow;
  }
  p->pLast = pRow;

*/
void graph_finish(GraphContext *p, int omitDescenders){
  GraphRow *pRow, *pDesc, *pDup, *pLoop;
  int i;
  u32 mask;
  u32 inUse;
  int hasDup = 0;    /* True if one or more isDup entries */
  const char *zTrunk;

  if( p==0 || p->pFirst==0 || p->nErr ) return;

  /* Initialize all rows */
  p->nHash = p->nRow*2 + 1;
  p->apHash = safeMalloc( sizeof(p->apHash[0])*p->nHash );
  for(pRow=p->pFirst; pRow; pRow=pRow->pNext){

      pParent->isLeaf = 0;
    }
  }

  /* Identify rows where the primary parent is off screen.  Assign
  ** each to a rail and draw descenders to the bottom of the screen.
  */
  zTrunk = persistBranchName(p, "trunk");
  for(i=0; i<2; i++){
    for(pRow=p->pFirst; pRow; pRow=pRow->pNext){
      if( i==0 ){
        if( pRow->zBranch!=zTrunk ) continue;
      }else {
        if( pRow->iRail>=0 ) continue;
      }
      if( pRow->nParent==0 || hashFind(p,pRow->aParent[0])==0 ){
        if( omitDescenders ){
          pRow->iRail = findFreeRail(p, pRow->idx, pRow->idx, 0, 0);
        }else{
          pRow->iRail = ++p->mxRail;
        }
        mask = 1<<(pRow->iRail);
        if( omitDescenders ){
          pRow->railInUse |= mask;
          if( pRow->pNext ) pRow->pNext->railInUse |= mask;
        }else{
          pRow->bDescender = pRow->nParent>0;
          for(pDesc=pRow; pDesc; pDesc=pDesc->pNext){
            pDesc->railInUse |= mask;
          }
        }
      }
    }
  }

  /* Assign rails to all rows that are still unassigned.
  ** The first primary child of a row goes on the same rail as

  blob_zero(&nonce);
  blob_zero(&pw);
  sha1sum_blob(pPayload, &nonce);
  blob_copy(&pw, &nonce);
  zLogin = g.urlUser;
  if( g.urlPasswd ){
    zPw = g.urlPasswd;
  }else if( g.cgiOutput ){
    /* Password failure while doing a sync from the web interface */
    cgi_printf("*** incorrect or missing password for user %h\n", zLogin);
    zPw = 0;
  }else{
    /* Password failure while doing a sync from the command-line interface */
    url_prompt_for_password();
    zPw = g.urlPasswd;
    if( !g.dontKeepUrl ) db_set("last-sync-pw", zPw, 0);
  }

  /* The login card wants the SHA1 hash of the password, so convert the
  ** password to its SHA1 hash it it isn't already a SHA1 hash.

      }
    }else if( rc==302 && strncasecmp(zLine, "location:", 9)==0 ){
      int i, j;
      for(i=9; zLine[i] && zLine[i]==' '; i++){}
      if( zLine[i]==0 ) fossil_fatal("malformed redirect: %s", zLine);
      j = strlen(zLine) - 1; 
      if( j>4 && strcmp(&zLine[j-4],"/xfer")==0 ) zLine[j-4] = 0;
      fossil_print("redirect to %s\n", &zLine[i]);
      url_parse(&zLine[i]);
      transport_close();
      http_exchange(pSend, pReply, useLogin);
      return;
    }
  }
  if( rc!=200 ){

  int rid;
  int isLeaf;
  int showDiff;
  const char *zName;

  login_check_credentials();
  if( !g.okRead ){ login_needed(); return; }
  zName = P("name");
  rid = name_to_rid_www("name");
  if( rid==0 ){
    style_header("Check-in Information Error");
    @ No such object: %h(g.argv[2])
    style_footer();
    return;
  }
  isLeaf = !db_exists("SELECT 1 FROM plink WHERE pid=%d", rid);

*/
void winfo_page(void){
  Stmt q;
  int rid;

  login_check_credentials();
  if( !g.okRdWiki ){ login_needed(); return; }
  rid = name_to_rid_www("name");
  if( rid==0 ){
    style_header("Wiki Page Information Error");
    @ No such object: %h(g.argv[2])
    style_footer();
    return;
  }
  db_prepare(&q, 

  Stmt q;
  char *zUuid;

  login_check_credentials();
  if( !g.okRead ){ login_needed(); return; }
  login_anonymous_available();

  rid = name_to_rid_www("name");
  if( rid==0 ){
    fossil_redirect_home();
  }
  zUuid = db_text(0, "SELECT uuid FROM blob WHERE rid=%d", rid);
  style_header("Check-in [%.10s]", zUuid);
  db_prepare(&q,
    "SELECT datetime(mtime), "

**
** If the object is a manifest, then mention:
**
**     * It's artifact ID
**     * date of check-in
**     * Comment & user
*/
void object_description(
  int rid,                 /* The artifact ID */
  int linkToView,          /* Add viewer link if true */
  Blob *pDownloadName      /* Fill with an appropriate download name */
){
  Stmt q;
  int cnt = 0;
  int nWiki = 0;

    }
    db_finalize(&q);
  }
  db_prepare(&q, 
    "SELECT target, filename, datetime(mtime), user, src"
    "  FROM attachment"
    " WHERE src=(SELECT uuid FROM blob WHERE rid=%d)"
    " ORDER BY mtime DESC /*sort*/",
    rid
  );
  while( db_step(&q)==SQLITE_ROW ){
    const char *zTarget = db_column_text(&q, 0);
    const char *zFilename = db_column_text(&q, 1);
    const char *zDate = db_column_text(&q, 2);
    const char *zUser = db_column_text(&q, 3);

void diff_page(void){
  int v1 = name_to_rid(P("v1"));
  int v2 = name_to_rid(P("v2"));
  Blob c1, c2, diff;

  login_check_credentials();
  if( !g.okRead ){ login_needed(); return; }
  if( v1==0 || v2==0 ) fossil_redirect_home();
  style_header("Diff");
  @ <h2>Differences From:</h2>
  @ <blockquote>
  object_description(v1, 1, 0);
  @ </blockquote>
  @ <h2>To:</h2>
  @ <blockquote>

** to view artifacts that are images.
*/
void rawartifact_page(void){
  int rid;
  const char *zMime;
  Blob content;

  rid = name_to_rid_www("name");
  zMime = PD("m","application/x-fossil-artifact");
  login_check_credentials();
  if( !g.okRead ){ login_needed(); return; }
  if( rid==0 ) fossil_redirect_home();
  content_get(rid, &content);
  cgi_set_content_type(zMime);
  cgi_set_content(&content);
}

/*
** Render a hex dump of a file.

*/
void hexdump_page(void){
  int rid;
  Blob content;
  Blob downloadName;
  char *zUuid;

  rid = name_to_rid_www("name");
  login_check_credentials();
  if( !g.okRead ){ login_needed(); return; }
  if( rid==0 ) fossil_redirect_home();
  if( g.okAdmin ){
    const char *zUuid = db_text("", "SELECT uuid FROM blob WHERE rid=%d", rid);
    if( db_exists("SELECT 1 FROM shun WHERE uuid='%s'", zUuid) ){
      style_submenu_element("Unshun","Unshun", "%s/shun?uuid=%s&sub=1",
            g.zTop, zUuid);
    }else{
      style_submenu_element("Shun","Shun", "%s/shun?shun=%s#addshun",

  @ <hr>
  content_get(rid, &content);
  @ <blockquote><pre>
  hexdump(&content);
  @ </pre></blockquote>
  style_footer();
}

/*
** Look for "ci" and "filename" query parameters.  If found, try to
** use them to extract the record ID of an artifact for the file.
*/
int artifact_from_ci_and_filename(void){
  const char *zFilename;
  const char *zCI;
  int cirid;
  Blob content;
  Manifest m;
  int i;

  zCI = P("ci");
  if( zCI==0 ) return 0;
  zFilename = P("filename");
  if( zFilename==0 ) return 0;
  cirid = name_to_rid_www("ci");
  if( !content_get(cirid, &content) ) return 0;
  if( !manifest_parse(&m, &content) ) return 0;
  if( m.type!=CFTYPE_MANIFEST ) return 0;
  for(i=0; i<m.nFile; i++){
    if( strcmp(zFilename, m.aFile[i].zName)==0 ){
      return db_int(0, "SELECT rid FROM blob WHERE uuid=%Q", m.aFile[i].zUuid);
    }
  }
  return 0;
}


/*
** WEBPAGE: artifact
** URL: /artifact?name=ARTIFACTID
** URL: /artifact?ci=CHECKIN&filename=PATH
** 
** Show the complete content of a file identified by ARTIFACTID
** as preformatted text.
*/
void artifact_page(void){
  int rid = 0;
  Blob content;
  const char *zMime;
  Blob downloadName;
  int renderAsWiki = 0;
  int renderAsHtml = 0;
  const char *zUuid;
  if( P("ci") && P("filename") ){
    rid = artifact_from_ci_and_filename();
  }
  if( rid==0 ){
    rid = name_to_rid_www("name");
  }

  login_check_credentials();
  if( !g.okRead ){ login_needed(); return; }
  if( rid==0 ) fossil_redirect_home();
  if( g.okAdmin ){
    const char *zUuid = db_text("", "SELECT uuid FROM blob WHERE rid=%d", rid);
    if( db_exists("SELECT 1 FROM shun WHERE uuid='%s'", zUuid) ){
      style_submenu_element("Unshun","Unshun", "%s/shun?uuid=%s&sub=1",
            g.zTop, zUuid);
    }else{
      style_submenu_element("Shun","Shun", "%s/shun?shun=%s#addshun",

  char *zDate;
  const char *zUuid;
  char zTktName[20];
  Manifest m;

  login_check_credentials();
  if( !g.okRdTkt ){ login_needed(); return; }
  rid = name_to_rid_www("name");
  if( rid==0 ){ fossil_redirect_home(); }
  zUuid = db_text("", "SELECT uuid FROM blob WHERE rid=%d", rid);
  if( g.okAdmin ){
    if( db_exists("SELECT 1 FROM shun WHERE uuid='%s'", zUuid) ){
      style_submenu_element("Unshun","Unshun", "%s/shun?uuid=%s&sub=1",
            g.zTop, zUuid);
    }else{

/*
** WEBPAGE: info
** URL: info/ARTIFACTID
**
** The argument is a artifact ID which might be a baseline or a file or
** a ticket changes or a wiki edit or something else. 
**
** Figure out what the artifact ID is and jump to it.
*/
void info_page(void){
  const char *zName;
  Blob uuid;
  int rid;
  
  zName = P("name");
  if( zName==0 ) fossil_redirect_home();
  if( validate16(zName, strlen(zName))
   && db_exists("SELECT 1 FROM ticket WHERE tkt_uuid GLOB '%q*'", zName) ){
    tktview_page();
    return;
  }
  blob_set(&uuid, zName);
  if( name_to_uuid(&uuid, 1) ){
    fossil_redirect_home();
  }

    }else{
      @ Cancel special tag <b>%h(zTagName)</b>
    }
  }
  db_finalize(&q);
  @ </td></tr>



  @ <tr><td align="right" valign="top"><b>Branching:</b></td>
  @ <td valign="top">
  @ <input type="checkbox" name="newbr"%s(zNewBrFlag)>
  @ Make this check-in the start of a new branch named:
  @ <input type="text" width="15" name="brname" value="%h(zNewBranch)">
  @ </td></tr>


  if( is_a_leaf(rid)
   && !db_exists("SELECT 1 FROM tagxref "
                 " WHERE tagid=%d AND rid=%d AND tagtype>0",
                 TAG_CLOSED, rid)
  ){
    @ <tr><td align="right" valign="top"><b>Leaf Closure:</b></td>

  char *zExtra;           /* Extra path information past the webpage name */
  char *zBaseURL;         /* Full text of the URL being served */
  char *zTop;             /* Parent directory of zPath */
  const char *zContentType;  /* The content type of the input HTTP request */
  int iErrPriority;       /* Priority of current error message */
  char *zErrMsg;          /* Text of an error message */
  Blob cgiIn;             /* Input to an xfer www method */
  int cgiOutput;          /* Write error and status messages to CGI */
  int xferPanic;          /* Write error messages in XFER protocol */
  int fullHttpReply;      /* True for full HTTP reply.  False for CGI reply */
  Th_Interp *interp;      /* The TH1 interpreter */
  FILE *httpIn;           /* Accept HTTP input from here */
  FILE *httpOut;          /* Send HTTP output here */
  int xlinkClusterOnly;   /* Set when cloning.  Only process clusters */
  int fTimeFormat;        /* 1 for UTC.  2 for localtime.  0 not yet selected */

  char *z;
  va_list ap;
  static int once = 1;
  mainInFatalError = 1;
  va_start(ap, zFormat);
  z = vmprintf(zFormat, ap);
  va_end(ap);
  if( g.cgiOutput && once ){
    once = 0;
    cgi_printf("<p><font color=\"red\">%h</font></p>", z);
    cgi_reply();
  }else{
    fprintf(stderr, "%s: %s\n", g.argv[0], z);
  }
  db_force_rollback();
  exit(1);
}
void fossil_fatal(const char *zFormat, ...){
  char *z;
  va_list ap;
  mainInFatalError = 1;
  va_start(ap, zFormat);
  z = vmprintf(zFormat, ap);
  va_end(ap);
  if( g.cgiOutput ){
    g.cgiOutput = 0;
    cgi_printf("<p><font color=\"red\">%h</font></p>", z);
    cgi_reply();
  }else{
    fprintf(stderr, "%s: %s\n", g.argv[0], z);
  }
  db_force_rollback();
  exit(1);

  char *z;
  va_list ap;
  if( mainInFatalError ) return;
  mainInFatalError = 1;
  va_start(ap, zFormat);
  z = vmprintf(zFormat, ap);
  va_end(ap);
  if( g.cgiOutput ){
    g.cgiOutput = 0;
    cgi_printf("<p><font color=\"red\">%h</font></p>", z);
    cgi_reply();
  }else{
    fprintf(stderr, "%s: %s\n", g.argv[0], z);
  }
  db_force_rollback();
  exit(1);
}


/* Print a warning message */
void fossil_warning(const char *zFormat, ...){
  char *z;
  va_list ap;
  va_start(ap, zFormat);
  z = vmprintf(zFormat, ap);
  va_end(ap);
  if( g.cgiOutput ){
    cgi_printf("<p><font color=\"red\">%h</font></p>", z);
  }else{
    fprintf(stderr, "%s: %s\n", g.argv[0], z);
  }
}

/*

  setmode(_fileno(g.httpIn), _O_BINARY);
#endif
#ifdef __EMX__
  /* Similar hack for OS/2 */
  setmode(fileno(g.httpOut), O_BINARY);
  setmode(fileno(g.httpIn), O_BINARY);
#endif
  g.cgiOutput = 1;
  blob_read_from_file(&config, zFile);
  while( blob_line(&config, &line) ){
    if( !blob_token(&line, &key) ) continue;
    if( blob_buffer(&key)[0]=='#' ) continue;
    if( blob_eq(&key, "debug:") && blob_token(&line, &value) ){
      g.fDebug = fopen(blob_str(&value), "a");
      blob_reset(&value);

void cmd_http(void){
  const char *zIpAddr;
  const char *zNotFound;
  zNotFound = find_option("notfound", 0, 1);
  if( g.argc!=2 && g.argc!=3 && g.argc!=6 ){
    cgi_panic("no repository specified");
  }
  g.cgiOutput = 1;
  g.fullHttpReply = 1;
  if( g.argc==6 ){
    g.httpIn = fopen(g.argv[3], "rb");
    g.httpOut = fopen(g.argv[4], "wb");
    zIpAddr = g.argv[5];
  }else{
    g.httpIn = stdin;

    fossil_fatal("unable to listen on TCP socket %d", iPort);
  }
  g.httpIn = stdin;
  g.httpOut = stdout;
  if( g.fHttpTrace || g.fSqlTrace ){
    fprintf(stderr, "====== SERVER pid %d =======\n", getpid());
  }
  g.cgiOutput = 1;
  find_server_repository(isUiCmd);
  g.zRepositoryName = enter_chroot_jail(g.zRepositoryName);
  cgi_handle_http_request(0);
  process_one_web_page(zNotFound);
#else
  /* Win32 implementation */
  if( isUiCmd ){

** If the input name matches "tag:*" then always resolve as a tag.
**
** If the input is not a tag, then try to match it as an ISO-8601 date
** string YYYY-MM-DD HH:MM:SS and pick the nearest check-in to that date.
** If the input is of the form "date:*" or "localtime:*" or "utc:*" then
** always resolve the name as a date.
**
** Return 0 on success.  Return 1 if the name cannot be resolved.
** Return 2 name is ambiguous.
*/
int name_to_uuid(Blob *pName, int iErrPriority){
  int rc;
  int sz;
  sz = blob_size(pName);
  if( sz>UUID_SIZE || sz<4 || !validate16(blob_buffer(pName), sz) ){
    char *zUuid;

    blob_append(pName, db_column_text(&q, 0), db_column_bytes(&q, 0));
    if( db_step(&q)==SQLITE_ROW ){
      fossil_error(iErrPriority, 
         "multiple artifacts match"
      );
      blob_reset(pName);
      db_finalize(&q);
      return 2;
    }
    db_finalize(&q);
    rc = 0;
  }else{
    rc = 0;
  }
  return rc;

/*
** Convert a name to a rid.  If the name is a small integer value then
** just use atoi() to do the conversion.  If the name contains alphabetic
** characters or is not an existing rid, then use name_to_uuid then
** convert the uuid to a rid.
**
** This routine is used by command-line routines to resolve command-line inputs
** into a rid.
*/
int name_to_rid(const char *zName){
  int i;
  int rid;
  Blob name;

    return 0;
  }else{
    rid = db_int(0, "SELECT rid FROM blob WHERE uuid=%B", &name);
    blob_reset(&name);
  }
  return rid;
}

/*
** WEBPAGE: ambiguous
** URL: /ambiguous?name=UUID&src=WEBPAGE
** 
** The UUID given by the name paramager is ambiguous.  Display a page
** that shows all possible choices and let the user select between them.
*/
void ambiguous_page(void){
  Stmt q;
  const char *zName = P("name");  
  const char *zSrc = P("src");
  char *z;
  
  if( zName==0 || zName[0]==0 || zSrc==0 || zSrc[0]==0 ){
    fossil_redirect_home();
  }
  style_header("Ambiguous Artifact ID");
  @ <p>The artifact id <b>%h(zName)</b> is ambiguous and might
  @ mean any of the following:
  @ <ol>
  z = mprintf("%s", zName);
  canonical16(z, strlen(z));
  db_prepare(&q, "SELECT uuid, rid FROM blob WHERE uuid GLOB '%q*'", z);
  while( db_step(&q)==SQLITE_ROW ){
    const char *zUuid = db_column_text(&q, 0);
    int rid = db_column_int(&q, 1);
    @ <li><p><a href="%s(g.zBaseURL)/%T(zSrc)/%S(zUuid)">
    @ %S(zUuid)</a> -
    object_description(rid, 0, 0);
    @ </p></li>
  }
  @ </ol>
  style_footer();
}

/*
** Convert the name in CGI parameter zParamName into a rid and return that
** rid.  If the CGI parameter is missing or is not a valid artifact tag,
** return 0.  If the CGI parameter is ambiguous, redirect to a page that
** shows all possibilities and do not return.
*/
int name_to_rid_www(const char *zParamName){
  int i, rc;
  int rid;
  const char *zName = P(zParamName);
  Blob name;

  if( zName==0 || zName[0]==0 ) return 0;
  blob_init(&name, zName, -1);
  rc = name_to_uuid(&name, -1);
  if( rc==1 ){
    blob_reset(&name);
    for(i=0; zName[i] && isdigit(zName[i]); i++){}
    if( zName[i]==0 ){
      rid = atoi(zName);
      if( db_exists("SELECT 1 FROM blob WHERE rid=%d", rid) ){
        return rid;
      }
    }
    return 0;
  }else if( rc==2 ){
    cgi_redirectf("%s/ambiguous/%T?src=%t", g.zTop, zName, g.zPath);
    return 0;
  }else{
    rid = db_int(0, "SELECT rid FROM blob WHERE uuid=%B", &name);
    blob_reset(&name);
  }
  return rid;
}

  g.iErrPriority = iPriority;
}
void fossil_error_reset(void){
  free(g.zErrMsg);
  g.zErrMsg = 0;
  g.iErrPriority = 0;
}

/*
** Write output for user consumption.  If g.cgiOutput is enabled, then
** send the output as part of the CGI reply.  If g.cgiOutput is false,
** then write on standard output.
*/
void fossil_print(const char *zFormat, ...){
  va_list ap;
  va_start(ap, zFormat);
  if( g.cgiOutput ){
    cgi_vprintf(zFormat, ap);
  }else{
    vprintf(zFormat, ap);
  }
}

    "Change the logo image for the server");
  setup_menu_entry("Shunned", "shun",
    "Show artifacts that are shunned by this repository");
  setup_menu_entry("Log", "rcvfromlist",
    "A record of received artifacts and their sources");
  setup_menu_entry("Stats", "stat",
    "Display repository statistics");


  @ </table>

  style_footer();
}

/*
** WEBPAGE: setup_ulist

  @ <p><b>Note:</b>  Your browser has probably cached the logo image, so
  @ you will probably need to press the Reload button on your browser after
  @ changing the logo to provoke your browser to reload the new logo image.
  @ </p>
  style_footer();
  db_end_transaction(0);
}

/******************************************************************************
** This file is an amalgamation of many separate C source files from SQLite
** version 3.6.23.  By combining all the individual C code files into this 
** single large file, the entire code can be compiled as a one translation
** unit.  This allows many compilers to do optimizations that would not be
** possible if the files were compiled separately.  Performance improvements
** of 5% are more are commonly seen when SQLite is compiled as a single
** translation unit.
**
** This file is all you need to compile SQLite.  To use SQLite in other

** integers to pointers.  The way you do this varies from one compiler
** to the next, so we have developed the following set of #if statements
** to generate appropriate macros for a wide range of compilers.
**
** The correct "ANSI" way to do this is to use the intptr_t type. 
** Unfortunately, that typedef is not available on all compilers, or
** if it is available, it requires an #include of specific headers
** that vary from one machine to the next.
**
** Ticket #3860:  The llvm-gcc-4.2 compiler from Apple chokes on
** the ((void*)&((char*)0)[X]) construct.  But MSVC chokes on ((void*)(X)).
** So we have to define the macros in different ways depending on the
** compiler.
*/
#if defined(__PTRDIFF_TYPE__)  /* This case should work for GCC */

** string contains the date and time of the check-in (UTC) and an SHA1
** hash of the entire source tree.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.6.23"
#define SQLITE_VERSION_NUMBER 3006023
#define SQLITE_SOURCE_ID      "2010-04-15 23:24:29 f96782b389b5b97b488dc5814f7082e0393f64cd"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros

** See also: [sqlite_version()] and [sqlite_source_id()].
*/
SQLITE_API const char sqlite3_version[] = SQLITE_VERSION;
SQLITE_API const char *sqlite3_libversion(void);
SQLITE_API const char *sqlite3_sourceid(void);
SQLITE_API int sqlite3_libversion_number(void);


/*
** CAPI3REF: Run-Time Library Compilation Options Diagnostics
**
** ^The sqlite3_compileoption_used() function returns 0 or 1 
** indicating whether the specified option was defined at 
** compile time.  ^The SQLITE_ prefix may be omitted from the 
** option name passed to sqlite3_compileoption_used().  

** ^Support for the diagnostic functions sqlite3_compileoption_used()
** and sqlite3_compileoption_get() may be omitted by specifing the 
** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
**
** See also: SQL functions [sqlite_compileoption_used()] and
** [sqlite_compileoption_get()] and the [compile_options pragma].
*/
#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
SQLITE_API int sqlite3_compileoption_used(const char *zOptName);
SQLITE_API const char *sqlite3_compileoption_get(int N);
#endif

/*
** CAPI3REF: Test To See If The Library Is Threadsafe
**
** ^The sqlite3_threadsafe() function returns zero if and only if
** SQLite was compiled mutexing code omitted due to the
** [SQLITE_THREADSAFE] compile-time option being set to 0.

** vary depending on the [SQLITE_CONFIG_SINGLETHREAD | configuration option]
** in the first argument.
**
** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
** ^If the option is unknown or SQLite is unable to set the option
** then this routine returns a non-zero [error code].
*/
SQLITE_API int sqlite3_config(int, ...);

/*
** CAPI3REF: Configure database connections

**
** The sqlite3_db_config() interface is used to make configuration
** changes to a [database connection].  The interface is similar to
** [sqlite3_config()] except that the changes apply to a single
** [database connection] (specified in the first argument).  The
** sqlite3_db_config() interface should only be used immediately after
** the database connection is created using [sqlite3_open()],
** [sqlite3_open16()], or [sqlite3_open_v2()].  
**
** The second argument to sqlite3_db_config(D,V,...)  is the
** configuration verb - an integer code that indicates what
** aspect of the [database connection] is being configured.
** The only choice for this value is [SQLITE_DBCONFIG_LOOKASIDE].
** New verbs are likely to be added in future releases of SQLite.
** Additional arguments depend on the verb.
**
** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
** the call is considered successful.
*/
SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);

/*
** CAPI3REF: Memory Allocation Routines

**
** An instance of this object defines the interface between SQLite
** and low-level memory allocation routines.
**
** This object is used in only one place in the SQLite interface.
** A pointer to an instance of this object is the argument to
** [sqlite3_config()] when the configuration option is

  int (*xInit)(void*);           /* Initialize the memory allocator */
  void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
  void *pAppData;                /* Argument to xInit() and xShutdown() */
};

/*
** CAPI3REF: Configuration Options

**
** These constants are the available integer configuration options that
** can be passed as the first argument to the [sqlite3_config()] interface.
**
** New configuration options may be added in future releases of SQLite.
** Existing configuration options might be discontinued.  Applications
** should check the return code from [sqlite3_config()] to make sure that

** object and uses it for page cache memory allocations.</dd>
**
** <dt>SQLITE_CONFIG_GETPCACHE</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** [sqlite3_pcache_methods] object.  SQLite copies of the current
** page cache implementation into that object.)^ </dd>
**
** <dt>SQLITE_CONFIG_LOG</dt>
** <dd> ^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
** function with a call signature of void(*)(void*,int,const char*), 
** and a pointer to void. ^If the function pointer is not NULL, it is
** invoked by [sqlite3_log()] to process each logging event.  ^If the
** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
** passed through as the first parameter to the application-defined logger
** function whenever that function is invoked.  ^The second parameter to
** the logger function is a copy of the first parameter to the corresponding
** [sqlite3_log()] call and is intended to be a [result code] or an
** [extended result code].  ^The third parameter passed to the logger is
** log message after formatting via [sqlite3_snprintf()].
** The SQLite logging interface is not reentrant; the logger function
** supplied by the application must not invoke any SQLite interface.
** In a multi-threaded application, the application-defined logger
** function must be threadsafe. </dd>
**
** </dl>
*/
#define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
#define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
#define SQLITE_CONFIG_SERIALIZED    3  /* nil */
#define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
#define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
#define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
#define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
#define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
#define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
/* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
#define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
#define SQLITE_CONFIG_PCACHE       14  /* sqlite3_pcache_methods* */
#define SQLITE_CONFIG_GETPCACHE    15  /* sqlite3_pcache_methods* */
#define SQLITE_CONFIG_LOG          16  /* xFunc, void* */

/*
** CAPI3REF: Database Connection Configuration Options

**
** These constants are the available integer configuration options that
** can be passed as the second argument to the [sqlite3_db_config()] interface.
**
** New configuration options may be added in future releases of SQLite.
** Existing configuration options might be discontinued.  Applications
** should check the return code from [sqlite3_db_config()] to make sure that

#define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
#define SQLITE_FUNCTION             31   /* NULL            Function Name   */
#define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
#define SQLITE_COPY                  0   /* No longer used */

/*
** CAPI3REF: Tracing And Profiling Functions

**
** These routines register callback functions that can be used for
** tracing and profiling the execution of SQL statements.
**
** ^The callback function registered by sqlite3_trace() is invoked at
** various times when an SQL statement is being run by [sqlite3_step()].
** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
** SQL statement text as the statement first begins executing.
** ^(Additional sqlite3_trace() callbacks might occur
** as each triggered subprogram is entered.  The callbacks for triggers
** contain a UTF-8 SQL comment that identifies the trigger.)^
**
** ^The callback function registered by sqlite3_profile() is invoked
** as each SQL statement finishes.  ^The profile callback contains
** the original statement text and an estimate of wall-clock time
** of how long that statement took to run.
*/
SQLITE_API void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
SQLITE_API SQLITE_EXPERIMENTAL void *sqlite3_profile(sqlite3*,
   void(*xProfile)(void*,const char*,sqlite3_uint64), void*);

/*
** CAPI3REF: Query Progress Callbacks
**
** ^This routine configures a callback function - the

);
SQLITE_API int sqlite3_collation_needed16(
  sqlite3*, 
  void*,
  void(*)(void*,sqlite3*,int eTextRep,const void*)
);

#ifdef SQLITE_HAS_CODEC
/*
** Specify the key for an encrypted database.  This routine should be
** called right after sqlite3_open().
**
** The code to implement this API is not available in the public release
** of SQLite.
*/

** hook returning non-zero, just as it would be with any other rollback.
**
** ^For the purposes of this API, a transaction is said to have been
** rolled back if an explicit "ROLLBACK" statement is executed, or
** an error or constraint causes an implicit rollback to occur.
** ^The rollback callback is not invoked if a transaction is
** automatically rolled back because the database connection is closed.


**
** See also the [sqlite3_update_hook()] interface.
*/
SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);

/*

** [sqlite3_auto_extension()] calls.)^
**
** ^This function disables automatic extensions in all threads.
*/
SQLITE_API void sqlite3_reset_auto_extension(void);

/*


** The interface to the virtual-table mechanism is currently considered
** to be experimental.  The interface might change in incompatible ways.
** If this is a problem for you, do not use the interface at this time.
**
** When the virtual-table mechanism stabilizes, we will declare the
** interface fixed, support it indefinitely, and remove this comment.
*/

/*
** Structures used by the virtual table interface
*/
typedef struct sqlite3_vtab sqlite3_vtab;
typedef struct sqlite3_index_info sqlite3_index_info;
typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
typedef struct sqlite3_module sqlite3_module;

/*
** CAPI3REF: Virtual Table Object
** KEYWORDS: sqlite3_module {virtual table module}

**
** This structure, sometimes called a a "virtual table module", 
** defines the implementation of a [virtual tables].  
** This structure consists mostly of methods for the module.
**
** ^A virtual table module is created by filling in a persistent
** instance of this structure and passing a pointer to that instance

                       void **ppArg);
  int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
};

/*
** CAPI3REF: Virtual Table Indexing Information
** KEYWORDS: sqlite3_index_info

**
** The sqlite3_index_info structure and its substructures is used to
** pass information into and receive the reply from the [xBestIndex]
** method of a [virtual table module].  The fields under **Inputs** are the
** inputs to xBestIndex and are read-only.  xBestIndex inserts its
** results into the **Outputs** fields.
**

#define SQLITE_INDEX_CONSTRAINT_LE    8
#define SQLITE_INDEX_CONSTRAINT_LT    16
#define SQLITE_INDEX_CONSTRAINT_GE    32
#define SQLITE_INDEX_CONSTRAINT_MATCH 64

/*
** CAPI3REF: Register A Virtual Table Implementation

**
** ^These routines are used to register a new [virtual table module] name.
** ^Module names must be registered before
** creating a new [virtual table] using the module and before using a
** preexisting [virtual table] for the module.
**
** ^The module name is registered on the [database connection] specified

** ^The sqlite3_create_module_v2() interface has a fifth parameter which
** is a pointer to a destructor for the pClientData.  ^SQLite will
** invoke the destructor function (if it is not NULL) when SQLite
** no longer needs the pClientData pointer.  ^The sqlite3_create_module()
** interface is equivalent to sqlite3_create_module_v2() with a NULL
** destructor.
*/
SQLITE_API int sqlite3_create_module(
  sqlite3 *db,               /* SQLite connection to register module with */
  const char *zName,         /* Name of the module */
  const sqlite3_module *p,   /* Methods for the module */
  void *pClientData          /* Client data for xCreate/xConnect */
);
SQLITE_API int sqlite3_create_module_v2(
  sqlite3 *db,               /* SQLite connection to register module with */
  const char *zName,         /* Name of the module */
  const sqlite3_module *p,   /* Methods for the module */
  void *pClientData,         /* Client data for xCreate/xConnect */
  void(*xDestroy)(void*)     /* Module destructor function */
);

/*
** CAPI3REF: Virtual Table Instance Object
** KEYWORDS: sqlite3_vtab

**
** Every [virtual table module] implementation uses a subclass
** of this object to describe a particular instance
** of the [virtual table].  Each subclass will
** be tailored to the specific needs of the module implementation.
** The purpose of this superclass is to define certain fields that are
** common to all module implementations.

  char *zErrMsg;                  /* Error message from sqlite3_mprintf() */
  /* Virtual table implementations will typically add additional fields */
};

/*
** CAPI3REF: Virtual Table Cursor Object
** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor}

**
** Every [virtual table module] implementation uses a subclass of the
** following structure to describe cursors that point into the
** [virtual table] and are used
** to loop through the virtual table.  Cursors are created using the
** [sqlite3_module.xOpen | xOpen] method of the module and are destroyed
** by the [sqlite3_module.xClose | xClose] method.  Cursors are used

struct sqlite3_vtab_cursor {
  sqlite3_vtab *pVtab;      /* Virtual table of this cursor */
  /* Virtual table implementations will typically add additional fields */
};

/*
** CAPI3REF: Declare The Schema Of A Virtual Table

**
** ^The [xCreate] and [xConnect] methods of a
** [virtual table module] call this interface
** to declare the format (the names and datatypes of the columns) of
** the virtual tables they implement.
*/
SQLITE_API int sqlite3_declare_vtab(sqlite3*, const char *zSQL);

/*
** CAPI3REF: Overload A Function For A Virtual Table

**
** ^(Virtual tables can provide alternative implementations of functions
** using the [xFindFunction] method of the [virtual table module].  
** But global versions of those functions
** must exist in order to be overloaded.)^
**
** ^(This API makes sure a global version of a function with a particular
** name and number of parameters exists.  If no such function exists
** before this API is called, a new function is created.)^  ^The implementation
** of the new function always causes an exception to be thrown.  So
** the new function is not good for anything by itself.  Its only
** purpose is to be a placeholder function that can be overloaded
** by a [virtual table].
*/
SQLITE_API int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);

/*
** The interface to the virtual-table mechanism defined above (back up
** to a comment remarkably similar to this one) is currently considered
** to be experimental.  The interface might change in incompatible ways.
** If this is a problem for you, do not use the interface at this time.
**
** When the virtual-table mechanism stabilizes, we will declare the
** interface fixed, support it indefinitely, and remove this comment.


*/

/*
** CAPI3REF: A Handle To An Open BLOB
** KEYWORDS: {BLOB handle} {BLOB handles}
**
** An instance of this object represents an open BLOB on which

SQLITE_API void sqlite3_mutex_free(sqlite3_mutex*);
SQLITE_API void sqlite3_mutex_enter(sqlite3_mutex*);
SQLITE_API int sqlite3_mutex_try(sqlite3_mutex*);
SQLITE_API void sqlite3_mutex_leave(sqlite3_mutex*);

/*
** CAPI3REF: Mutex Methods Object

**
** An instance of this structure defines the low-level routines
** used to allocate and use mutexes.
**
** Usually, the default mutex implementations provided by SQLite are
** sufficient, however the user has the option of substituting a custom
** implementation for specialized deployments or systems for which SQLite

#define SQLITE_TESTCTRL_RESERVE                 14
#define SQLITE_TESTCTRL_OPTIMIZATIONS           15
#define SQLITE_TESTCTRL_ISKEYWORD               16
#define SQLITE_TESTCTRL_LAST                    16

/*
** CAPI3REF: SQLite Runtime Status

**
** ^This interface is used to retrieve runtime status information
** about the preformance of SQLite, and optionally to reset various
** highwater marks.  ^The first argument is an integer code for
** the specific parameter to measure.  ^(Recognized integer codes
** are of the form [SQLITE_STATUS_MEMORY_USED | SQLITE_STATUS_...].)^
** ^The current value of the parameter is returned into *pCurrent.

** interfaces.  However the values returned in *pCurrent and
** *pHighwater reflect the status of SQLite at different points in time
** and it is possible that another thread might change the parameter
** in between the times when *pCurrent and *pHighwater are written.
**
** See also: [sqlite3_db_status()]
*/
SQLITE_API int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag);


/*
** CAPI3REF: Status Parameters

**
** These integer constants designate various run-time status parameters
** that can be returned by [sqlite3_status()].
**
** <dl>
** ^(<dt>SQLITE_STATUS_MEMORY_USED</dt>
** <dd>This parameter is the current amount of memory checked out

#define SQLITE_STATUS_MALLOC_SIZE          5
#define SQLITE_STATUS_PARSER_STACK         6
#define SQLITE_STATUS_PAGECACHE_SIZE       7
#define SQLITE_STATUS_SCRATCH_SIZE         8

/*
** CAPI3REF: Database Connection Status

**
** ^This interface is used to retrieve runtime status information 
** about a single [database connection].  ^The first argument is the
** database connection object to be interrogated.  ^The second argument
** is an integer constant, taken from the set of
** [SQLITE_DBSTATUS_LOOKASIDE_USED | SQLITE_DBSTATUS_*] macros, that
** determiness the parameter to interrogate.  The set of 
** [SQLITE_DBSTATUS_LOOKASIDE_USED | SQLITE_DBSTATUS_*] macros is likely
** to grow in future releases of SQLite.
**
** ^The current value of the requested parameter is written into *pCur
** and the highest instantaneous value is written into *pHiwtr.  ^If
** the resetFlg is true, then the highest instantaneous value is
** reset back down to the current value.
**
** See also: [sqlite3_status()] and [sqlite3_stmt_status()].
*/
SQLITE_API int sqlite3_db_status(sqlite3*, int op, int *pCur, int *pHiwtr, int resetFlg);

/*
** CAPI3REF: Status Parameters for database connections

**
** These constants are the available integer "verbs" that can be passed as
** the second argument to the [sqlite3_db_status()] interface.
**
** New verbs may be added in future releases of SQLite. Existing verbs
** might be discontinued. Applications should check the return code from
** [sqlite3_db_status()] to make sure that the call worked.
** The [sqlite3_db_status()] interface will return a non-zero error code
** if a discontinued or unsupported verb is invoked.
**
** <dl>
** ^(<dt>SQLITE_DBSTATUS_LOOKASIDE_USED</dt>
** <dd>This parameter returns the number of lookaside memory slots currently
** checked out.</dd>)^
**
** <dt>SQLITE_DBSTATUS_CACHE_USED</dt>
** <dd>^This parameter returns the approximate number of of bytes of heap
** memory used by all pager caches associated with the database connection.
** ^The highwater mark associated with SQLITE_DBSTATUS_CACHE_USED is always 0.
** checked out.</dd>)^
** </dl>
*/
#define SQLITE_DBSTATUS_LOOKASIDE_USED     0
#define SQLITE_DBSTATUS_CACHE_USED         1
#define SQLITE_DBSTATUS_MAX                1   /* Largest defined DBSTATUS */


/*
** CAPI3REF: Prepared Statement Status

**
** ^(Each prepared statement maintains various
** [SQLITE_STMTSTATUS_SORT | counters] that measure the number
** of times it has performed specific operations.)^  These counters can
** be used to monitor the performance characteristics of the prepared
** statements.  For example, if the number of table steps greatly exceeds
** the number of table searches or result rows, that would tend to indicate

** to be interrogated.)^
** ^The current value of the requested counter is returned.
** ^If the resetFlg is true, then the counter is reset to zero after this
** interface call returns.
**
** See also: [sqlite3_status()] and [sqlite3_db_status()].
*/
SQLITE_API int sqlite3_stmt_status(sqlite3_stmt*, int op,int resetFlg);

/*
** CAPI3REF: Status Parameters for prepared statements

**
** These preprocessor macros define integer codes that name counter
** values associated with the [sqlite3_stmt_status()] interface.
** The meanings of the various counters are as follows:
**
** <dl>
** <dt>SQLITE_STMTSTATUS_FULLSCAN_STEP</dt>
** <dd>^This is the number of times that SQLite has stepped forward in
** a table as part of a full table scan.  Large numbers for this counter
** may indicate opportunities for performance improvement through 
** careful use of indices.</dd>
**
** <dt>SQLITE_STMTSTATUS_SORT</dt>
** <dd>^This is the number of sort operations that have occurred.
** A non-zero value in this counter may indicate an opportunity to
** improvement performance through careful use of indices.</dd>
**
** <dt>SQLITE_STMTSTATUS_AUTOINDEX</dt>
** <dd>^This is the number of rows inserted into transient indices that
** were created automatically in order to help joins run faster.
** A non-zero value in this counter may indicate an opportunity to
** improvement performance by adding permanent indices that do not
** need to be reinitialized each time the statement is run.</dd>
**
** </dl>
*/
#define SQLITE_STMTSTATUS_FULLSCAN_STEP     1
#define SQLITE_STMTSTATUS_SORT              2
#define SQLITE_STMTSTATUS_AUTOINDEX         3

/*
** CAPI3REF: Custom Page Cache Object

**
** The sqlite3_pcache type is opaque.  It is implemented by
** the pluggable module.  The SQLite core has no knowledge of
** its size or internal structure and never deals with the
** sqlite3_pcache object except by holding and passing pointers
** to the object.
**
** See [sqlite3_pcache_methods] for additional information.
*/
typedef struct sqlite3_pcache sqlite3_pcache;

/*
** CAPI3REF: Application Defined Page Cache.
** KEYWORDS: {page cache}

**
** ^(The [sqlite3_config]([SQLITE_CONFIG_PCACHE], ...) interface can
** register an alternative page cache implementation by passing in an 
** instance of the sqlite3_pcache_methods structure.)^ The majority of the 
** heap memory used by SQLite is used by the page cache to cache data read 
** from, or ready to be written to, the database file. By implementing a 
** custom page cache using this API, an application can control more 

  void (*xRekey)(sqlite3_pcache*, void*, unsigned oldKey, unsigned newKey);
  void (*xTruncate)(sqlite3_pcache*, unsigned iLimit);
  void (*xDestroy)(sqlite3_pcache*);
};

/*
** CAPI3REF: Online Backup Object

**
** The sqlite3_backup object records state information about an ongoing
** online backup operation.  ^The sqlite3_backup object is created by
** a call to [sqlite3_backup_init()] and is destroyed by a call to
** [sqlite3_backup_finish()].
**
** See Also: [Using the SQLite Online Backup API]
*/
typedef struct sqlite3_backup sqlite3_backup;

/*
** CAPI3REF: Online Backup API.

**
** The backup API copies the content of one database into another.
** It is useful either for creating backups of databases or
** for copying in-memory databases to or from persistent files. 
**
** See Also: [Using the SQLite Online Backup API]
**

SQLITE_API int sqlite3_backup_step(sqlite3_backup *p, int nPage);
SQLITE_API int sqlite3_backup_finish(sqlite3_backup *p);
SQLITE_API int sqlite3_backup_remaining(sqlite3_backup *p);
SQLITE_API int sqlite3_backup_pagecount(sqlite3_backup *p);

/*
** CAPI3REF: Unlock Notification

**
** ^When running in shared-cache mode, a database operation may fail with
** an [SQLITE_LOCKED] error if the required locks on the shared-cache or
** individual tables within the shared-cache cannot be obtained. See
** [SQLite Shared-Cache Mode] for a description of shared-cache locking. 
** ^This API may be used to register a callback that SQLite will invoke 
** when the connection currently holding the required lock relinquishes it.

  void (*xNotify)(void **apArg, int nArg),    /* Callback function to invoke */
  void *pNotifyArg                            /* Argument to pass to xNotify */
);


/*
** CAPI3REF: String Comparison

**
** ^The [sqlite3_strnicmp()] API allows applications and extensions to
** compare the contents of two buffers containing UTF-8 strings in a
** case-indendent fashion, using the same definition of case independence 
** that SQLite uses internally when comparing identifiers.
*/
SQLITE_API int sqlite3_strnicmp(const char *, const char *, int);

/*
** CAPI3REF: Error Logging Interface

**
** ^The [sqlite3_log()] interface writes a message into the error log
** established by the [SQLITE_CONFIG_LOG] option to [sqlite3_config()].
** ^If logging is enabled, the zFormat string and subsequent arguments are
** used with [sqlite3_snprintf()] to generate the final output string.
**
** The sqlite3_log() interface is intended for use by extensions such as
** virtual tables, collating functions, and SQL functions.  While there is
** nothing to prevent an application from calling sqlite3_log(), doing so
** is considered bad form.
**
** The zFormat string must not be NULL.

/*
** If compiling for a processor that lacks floating point support,
** substitute integer for floating-point
*/
#ifdef SQLITE_OMIT_FLOATING_POINT
# define double sqlite_int64
# define float sqlite_int64
# define LONGDOUBLE_TYPE sqlite_int64
# ifndef SQLITE_BIG_DBL
#   define SQLITE_BIG_DBL (((sqlite3_int64)1)<<50)
# endif
# define SQLITE_OMIT_DATETIME_FUNCS 1
# define SQLITE_OMIT_TRACE 1
# undef SQLITE_MIXED_ENDIAN_64BIT_FLOAT

SQLITE_PRIVATE int sqlite3BtreeClose(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSetCacheSize(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeSetSafetyLevel(Btree*,int,int);
SQLITE_PRIVATE int sqlite3BtreeSyncDisabled(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSetPageSize(Btree *p, int nPagesize, int nReserve, int eFix);
SQLITE_PRIVATE int sqlite3BtreeGetPageSize(Btree*);
SQLITE_PRIVATE int sqlite3BtreeMaxPageCount(Btree*,int);
SQLITE_PRIVATE u32 sqlite3BtreeLastPage(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSecureDelete(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeGetReserve(Btree*);
SQLITE_PRIVATE int sqlite3BtreeSetAutoVacuum(Btree *, int);
SQLITE_PRIVATE int sqlite3BtreeGetAutoVacuum(Btree *);
SQLITE_PRIVATE int sqlite3BtreeBeginTrans(Btree*,int);
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseOne(Btree*, const char *zMaster);
SQLITE_PRIVATE int sqlite3BtreeCommitPhaseTwo(Btree*);

#define OP_AutoCommit                          33
#define OP_Transaction                         34
#define OP_ReadCookie                          35
#define OP_SetCookie                           36
#define OP_VerifyCookie                        37
#define OP_OpenRead                            38
#define OP_OpenWrite                           39
#define OP_OpenAutoindex                       40
#define OP_OpenEphemeral                       41
#define OP_OpenPseudo                          42
#define OP_Close                               43
#define OP_SeekLt                              44
#define OP_SeekLe                              45
#define OP_SeekGe                              46
#define OP_SeekGt                              47
#define OP_Seek                                48
#define OP_NotFound                            49
#define OP_Found                               50
#define OP_IsUnique                            51
#define OP_NotExists                           52
#define OP_Sequence                            53
#define OP_NewRowid                            54
#define OP_Insert                              55
#define OP_InsertInt                           56
#define OP_Delete                              57
#define OP_ResetCount                          58
#define OP_RowKey                              59
#define OP_RowData                             60
#define OP_Rowid                               61
#define OP_NullRow                             62
#define OP_Last                                63
#define OP_Sort                                64
#define OP_Rewind                              65
#define OP_Prev                                66
#define OP_Next                                67
#define OP_IdxInsert                           70
#define OP_IdxDelete                           71
#define OP_IdxRowid                            72
#define OP_IdxLT                               81
#define OP_IdxGE                               92
#define OP_Destroy                             95
#define OP_Clear                               96
#define OP_CreateIndex                         97
#define OP_CreateTable                         98
#define OP_ParseSchema                         99
#define OP_LoadAnalysis                       100
#define OP_DropTable                          101
#define OP_DropIndex                          102
#define OP_DropTrigger                        103
#define OP_IntegrityCk                        104
#define OP_RowSetAdd                          105
#define OP_RowSetRead                         106
#define OP_RowSetTest                         107
#define OP_Program                            108
#define OP_Param                              109
#define OP_FkCounter                          110
#define OP_FkIfZero                           111
#define OP_MemMax                             112
#define OP_IfPos                              113
#define OP_IfNeg                              114
#define OP_IfZero                             115
#define OP_AggStep                            116
#define OP_AggFinal                           117
#define OP_Vacuum                             118
#define OP_IncrVacuum                         119
#define OP_Expire                             120
#define OP_TableLock                          121
#define OP_VBegin                             122
#define OP_VCreate                            123
#define OP_VDestroy                           124
#define OP_VOpen                              125
#define OP_VFilter                            126
#define OP_VColumn                            127
#define OP_VNext                              128
#define OP_VRename                            129
#define OP_VUpdate                            131
#define OP_Pagecount                          132
#define OP_Trace                              133
#define OP_Noop                               134
#define OP_Explain                            135

/* The following opcode values are never used */

#define OP_NotUsed_136                        136
#define OP_NotUsed_137                        137
#define OP_NotUsed_138                        138
#define OP_NotUsed_139                        139
#define OP_NotUsed_140                        140

#define OPFLG_OUT3            0x0040  /* out3:  P3 is an output */
#define OPFLG_INITIALIZER {\
/*   0 */ 0x00, 0x01, 0x05, 0x04, 0x04, 0x10, 0x00, 0x02,\
/*   8 */ 0x02, 0x02, 0x02, 0x02, 0x00, 0x00, 0x24, 0x24,\
/*  16 */ 0x00, 0x00, 0x00, 0x24, 0x04, 0x05, 0x04, 0x00,\
/*  24 */ 0x00, 0x01, 0x05, 0x05, 0x00, 0x00, 0x00, 0x02,\
/*  32 */ 0x00, 0x00, 0x00, 0x02, 0x10, 0x00, 0x00, 0x00,\
/*  40 */ 0x00, 0x00, 0x00, 0x00, 0x11, 0x11, 0x11, 0x11,\
/*  48 */ 0x08, 0x11, 0x11, 0x11, 0x11, 0x02, 0x02, 0x00,\
/*  56 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x00, 0x01,\
/*  64 */ 0x01, 0x01, 0x01, 0x01, 0x4c, 0x4c, 0x08, 0x00,\
/*  72 */ 0x02, 0x05, 0x05, 0x15, 0x15, 0x15, 0x15, 0x15,\
/*  80 */ 0x15, 0x01, 0x4c, 0x4c, 0x4c, 0x4c, 0x4c, 0x4c,\
/*  88 */ 0x4c, 0x4c, 0x4c, 0x4c, 0x01, 0x24, 0x02, 0x02,\
/*  96 */ 0x00, 0x02, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00,\
/* 104 */ 0x00, 0x0c, 0x45, 0x15, 0x01, 0x02, 0x00, 0x01,\
/* 112 */ 0x08, 0x05, 0x05, 0x05, 0x00, 0x00, 0x00, 0x01,\
/* 120 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00,\
/* 128 */ 0x01, 0x00, 0x02, 0x00, 0x02, 0x00, 0x00, 0x00,\
/* 136 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x04, 0x04,\
/* 144 */ 0x04, 0x04,}

/************** End of opcodes.h *********************************************/
/************** Continuing where we left off in vdbe.h ***********************/

/*

SQLITE_PRIVATE int sqlite3PagerOpenSavepoint(Pager *pPager, int n);
SQLITE_PRIVATE int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint);
SQLITE_PRIVATE int sqlite3PagerSharedLock(Pager *pPager);

/* Functions used to query pager state and configuration. */
SQLITE_PRIVATE u8 sqlite3PagerIsreadonly(Pager*);
SQLITE_PRIVATE int sqlite3PagerRefcount(Pager*);
SQLITE_PRIVATE int sqlite3PagerMemUsed(Pager*);
SQLITE_PRIVATE const char *sqlite3PagerFilename(Pager*);
SQLITE_PRIVATE const sqlite3_vfs *sqlite3PagerVfs(Pager*);
SQLITE_PRIVATE sqlite3_file *sqlite3PagerFile(Pager*);
SQLITE_PRIVATE const char *sqlite3PagerJournalname(Pager*);
SQLITE_PRIVATE int sqlite3PagerNosync(Pager*);
SQLITE_PRIVATE void *sqlite3PagerTempSpace(Pager*);
SQLITE_PRIVATE int sqlite3PagerIsMemdb(Pager*);

#define SQLITE_LegacyFileFmt  0x00100000  /* Create new databases in format 1 */
#define SQLITE_FullFSync      0x00200000  /* Use full fsync on the backend */
#define SQLITE_LoadExtension  0x00400000  /* Enable load_extension */
#define SQLITE_RecoveryMode   0x00800000  /* Ignore schema errors */
#define SQLITE_ReverseOrder   0x01000000  /* Reverse unordered SELECTs */
#define SQLITE_RecTriggers    0x02000000  /* Enable recursive triggers */
#define SQLITE_ForeignKeys    0x04000000  /* Enforce foreign key constraints  */
#define SQLITE_AutoIndex      0x08000000  /* Enable automatic indexes */

/*
** Bits of the sqlite3.flags field that are used by the
** sqlite3_test_control(SQLITE_TESTCTRL_OPTIMIZATIONS,...) interface.
** These must be the low-order bits of the flags field.
*/
#define SQLITE_QueryFlattener 0x01        /* Disable query flattening */

** such a table must be a simple name: ID.  But in SQLite, the table can
** now be identified by a database name, a dot, then the table name: ID.ID.
**
** The jointype starts out showing the join type between the current table
** and the next table on the list.  The parser builds the list this way.
** But sqlite3SrcListShiftJoinType() later shifts the jointypes so that each
** jointype expresses the join between the table and the previous table.
**
** In the colUsed field, the high-order bit (bit 63) is set if the table
** contains more than 63 columns and the 64-th or later column is used.
*/
struct SrcList {
  i16 nSrc;        /* Number of tables or subqueries in the FROM clause */
  i16 nAlloc;      /* Number of entries allocated in a[] below */
  struct SrcList_item {
    char *zDatabase;  /* Name of database holding this table */
    char *zName;      /* Name of the table */

** and the WhereInfo.wctrlFlags member.
*/
#define WHERE_ORDERBY_NORMAL   0x0000 /* No-op */
#define WHERE_ORDERBY_MIN      0x0001 /* ORDER BY processing for min() func */
#define WHERE_ORDERBY_MAX      0x0002 /* ORDER BY processing for max() func */
#define WHERE_ONEPASS_DESIRED  0x0004 /* Want to do one-pass UPDATE/DELETE */
#define WHERE_DUPLICATES_OK    0x0008 /* Ok to return a row more than once */
#define WHERE_OMIT_OPEN        0x0010 /* Table cursors are already open */
#define WHERE_OMIT_CLOSE       0x0020 /* Omit close of table & index cursors */
#define WHERE_FORCE_TABLE      0x0040 /* Do not use an index-only search */
#define WHERE_ONETABLE_ONLY    0x0080 /* Only code the 1st table in pTabList */

/*
** The WHERE clause processing routine has two halves.  The
** first part does the start of the WHERE loop and the second

  u8 untestedTerms;    /* Not all WHERE terms resolved by outer loop */
  SrcList *pTabList;             /* List of tables in the join */
  int iTop;                      /* The very beginning of the WHERE loop */
  int iContinue;                 /* Jump here to continue with next record */
  int iBreak;                    /* Jump here to break out of the loop */
  int nLevel;                    /* Number of nested loop */
  struct WhereClause *pWC;       /* Decomposition of the WHERE clause */
  double savedNQueryLoop;        /* pParse->nQueryLoop outside the WHERE loop */
  WhereLevel a[1];               /* Information about each nest loop in WHERE */
};

/*
** A NameContext defines a context in which to resolve table and column
** names.  The context consists of a list of tables (the pSrcList) field and
** a list of named expression (pEList).  The named expression list may

  Parse *pToplevel;    /* Parse structure for main program (or NULL) */
  Table *pTriggerTab;  /* Table triggers are being coded for */
  u32 oldmask;         /* Mask of old.* columns referenced */
  u32 newmask;         /* Mask of new.* columns referenced */
  u8 eTriggerOp;       /* TK_UPDATE, TK_INSERT or TK_DELETE */
  u8 eOrconf;          /* Default ON CONFLICT policy for trigger steps */
  u8 disableTriggers;  /* True to disable triggers */
  double nQueryLoop;   /* Estimated number of iterations of a query */

  /* Above is constant between recursions.  Below is reset before and after
  ** each recursion */

  int nVar;            /* Number of '?' variables seen in the SQL so far */
  int nVarExpr;        /* Number of used slots in apVarExpr[] */
  int nVarExprAlloc;   /* Number of allocated slots in apVarExpr[] */

SQLITE_PRIVATE   void sqlite3VdbeIOTraceSql(Vdbe*);
SQLITE_PRIVATE void (*sqlite3IoTrace)(const char*,...);
#else
# define IOTRACE(A)
# define sqlite3VdbeIOTraceSql(X)
#endif

/*
** These routines are available for the mem2.c debugging memory allocator
** only.  They are used to verify that different "types" of memory
** allocations are properly tracked by the system.
**
** sqlite3MemdebugSetType() sets the "type" of an allocation to one of
** the MEMTYPE_* macros defined below.  The type must be a bitmask with
** a single bit set.
**
** sqlite3MemdebugHasType() returns true if any of the bits in its second
** argument match the type set by the previous sqlite3MemdebugSetType().
** sqlite3MemdebugHasType() is intended for use inside assert() statements.
** For example:
**
**     assert( sqlite3MemdebugHasType(p, MEMTYPE_HEAP) );
**
** Perhaps the most important point is the difference between MEMTYPE_HEAP
** and MEMTYPE_DB.  If an allocation is MEMTYPE_DB, that means it might have
** been allocated by lookaside, except the allocation was too large or
** lookaside was already full.  It is important to verify that allocations
** that might have been satisfied by lookaside are not passed back to 
** non-lookaside free() routines.  Asserts such as the example above are
** placed on the non-lookaside free() routines to verify this constraint. 
**
** All of this is no-op for a production build.  It only comes into
** play when the SQLITE_MEMDEBUG compile-time option is used.
*/
#ifdef SQLITE_MEMDEBUG
SQLITE_PRIVATE   void sqlite3MemdebugSetType(void*,u8);
SQLITE_PRIVATE   int sqlite3MemdebugHasType(void*,u8);
#else
# define sqlite3MemdebugSetType(X,Y)  /* no-op */
# define sqlite3MemdebugHasType(X,Y)  1
#endif
#define MEMTYPE_HEAP     0x01    /* General heap allocations */
#define MEMTYPE_DB       0x02    /* Associated with a database connection */
#define MEMTYPE_SCRATCH  0x04    /* Scratch allocations */
#define MEMTYPE_PCACHE   0x08    /* Page cache allocations */

#endif /* _SQLITEINT_H_ */

/************** End of sqliteInt.h *******************************************/
/************** Begin file global.c ******************************************/
/*
** 2008 June 13
**
** The author disclaims copyright to this source code.  In place of

  "OMIT_AUTHORIZATION",
#endif
#ifdef SQLITE_OMIT_AUTOINCREMENT
  "OMIT_AUTOINCREMENT",
#endif
#ifdef SQLITE_OMIT_AUTOINIT
  "OMIT_AUTOINIT",
#endif
#ifdef SQLITE_OMIT_AUTOMATIC_INDEX
  "OMIT_AUTOMATIC_INDEX",
#endif
#ifdef SQLITE_OMIT_AUTOVACUUM
  "OMIT_AUTOVACUUM",
#endif
#ifdef SQLITE_OMIT_BETWEEN_OPTIMIZATION
  "OMIT_BETWEEN_OPTIMIZATION",
#endif

      *pCurrent = db->lookaside.nOut;
      *pHighwater = db->lookaside.mxOut;
      if( resetFlag ){
        db->lookaside.mxOut = db->lookaside.nOut;
      }
      break;
    }

    /* 
    ** Return an approximation for the amount of memory currently used
    ** by all pagers associated with the given database connection.  The
    ** highwater mark is meaningless and is returned as zero.
    */
    case SQLITE_DBSTATUS_CACHE_USED: {
      int totalUsed = 0;
      int i;
      for(i=0; i<db->nDb; i++){
        Btree *pBt = db->aDb[i].pBt;
        if( pBt ){
          Pager *pPager = sqlite3BtreePager(pBt);
          totalUsed += sqlite3PagerMemUsed(pPager);
        }
      }
      *pCurrent = totalUsed;
      *pHighwater = 0;
      break;
    }
    default: {
      return SQLITE_ERROR;
    }
  }
  return SQLITE_OK;
}

** MemBlockHdr.
*/
struct MemBlockHdr {
  i64 iSize;                          /* Size of this allocation */
  struct MemBlockHdr *pNext, *pPrev;  /* Linked list of all unfreed memory */
  char nBacktrace;                    /* Number of backtraces on this alloc */
  char nBacktraceSlots;               /* Available backtrace slots */
  u8 nTitle;                          /* Bytes of title; includes '\0' */
  u8 eType;                           /* Allocation type code */
  int iForeGuard;                     /* Guard word for sanity */
};

/*
** Guard words
*/
#define FOREGUARD 0x80F5E153

    if( mem.pLast ){
      mem.pLast->pNext = pHdr;
    }else{
      mem.pFirst = pHdr;
    }
    mem.pLast = pHdr;
    pHdr->iForeGuard = FOREGUARD;
    pHdr->eType = MEMTYPE_HEAP;
    pHdr->nBacktraceSlots = mem.nBacktrace;
    pHdr->nTitle = mem.nTitle;
    if( mem.nBacktrace ){
      void *aAddr[40];
      pHdr->nBacktrace = backtrace(aAddr, mem.nBacktrace+1)-1;
      memcpy(pBt, &aAddr[1], pHdr->nBacktrace*sizeof(void*));
      assert(pBt[0]);

     sqlite3MemRoundup,
     sqlite3MemInit,
     sqlite3MemShutdown,
     0
  };
  sqlite3_config(SQLITE_CONFIG_MALLOC, &defaultMethods);
}

/*
** Set the "type" of an allocation.
*/
SQLITE_PRIVATE void sqlite3MemdebugSetType(void *p, u8 eType){
  if( p ){
    struct MemBlockHdr *pHdr;
    pHdr = sqlite3MemsysGetHeader(p);
    assert( pHdr->iForeGuard==FOREGUARD );
    pHdr->eType = eType;
  }
}

/*
** Return TRUE if the mask of type in eType matches the type of the
** allocation p.  Also return true if p==NULL.
**
** This routine is designed for use within an assert() statement, to
** verify the type of an allocation.  For example:
**
**     assert( sqlite3MemdebugHasType(p, MEMTYPE_DB) );
*/
SQLITE_PRIVATE int sqlite3MemdebugHasType(void *p, u8 eType){
  int rc = 1;
  if( p ){
    struct MemBlockHdr *pHdr;
    pHdr = sqlite3MemsysGetHeader(p);
    assert( pHdr->iForeGuard==FOREGUARD );         /* Allocation is valid */
    assert( (pHdr->eType & (pHdr->eType-1))==0 );  /* Only one type bit set */
    if( (pHdr->eType&eType)==0 ){
      void **pBt;
      pBt = (void**)pHdr;
      pBt -= pHdr->nBacktraceSlots;
      backtrace_symbols_fd(pBt, pHdr->nBacktrace, fileno(stderr));
      fprintf(stderr, "\n");
      rc = 0;
    }
  }
  return rc;
}
 

/*
** Set the number of backtrace levels kept for each allocation.
** A value of zero turns off backtracing.  The number is always rounded
** up to a multiple of 2.
*/
SQLITE_PRIVATE void sqlite3MemdebugBacktrace(int depth){

    sqlite3StatusSet(SQLITE_STATUS_SCRATCH_SIZE, n);
    n = mallocWithAlarm(n, &p);
    if( p ) sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_OVERFLOW, n);
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    p = sqlite3GlobalConfig.m.xMalloc(n);
  }
  sqlite3MemdebugSetType(p, MEMTYPE_SCRATCH);
#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
  scratchAllocOut = p!=0;
#endif
  return p;    
}
SQLITE_PRIVATE void sqlite3ScratchFree(void *p){
  if( p ){

#if SQLITE_THREADSAFE==0 && !defined(NDEBUG)
    /* Verify that no more than one scratch allocation per thread
    ** is outstanding at one time.  (This is only checked in the
    ** single-threaded case since checking in the multi-threaded case
    ** would be much more complicated.) */
    assert( scratchAllocOut==1 );
    scratchAllocOut = 0;
#endif

    if( sqlite3GlobalConfig.pScratch==0
           || p<sqlite3GlobalConfig.pScratch
           || p>=(void*)mem0.aScratchFree ){
      assert( sqlite3MemdebugHasType(p, MEMTYPE_SCRATCH) );
      sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
      if( sqlite3GlobalConfig.bMemstat ){
        int iSize = sqlite3MallocSize(p);
        sqlite3_mutex_enter(mem0.mutex);
        sqlite3StatusAdd(SQLITE_STATUS_SCRATCH_OVERFLOW, -iSize);
        sqlite3StatusAdd(SQLITE_STATUS_MEMORY_USED, -iSize);
        sqlite3GlobalConfig.m.xFree(p);
        sqlite3_mutex_leave(mem0.mutex);

#endif

/*
** Return the size of a memory allocation previously obtained from
** sqlite3Malloc() or sqlite3_malloc().
*/
SQLITE_PRIVATE int sqlite3MallocSize(void *p){
  assert( sqlite3MemdebugHasType(p, MEMTYPE_HEAP) );
  return sqlite3GlobalConfig.m.xSize(p);
}
SQLITE_PRIVATE int sqlite3DbMallocSize(sqlite3 *db, void *p){
  assert( db==0 || sqlite3_mutex_held(db->mutex) );
  if( isLookaside(db, p) ){
    return db->lookaside.sz;
  }else{
    assert( sqlite3MemdebugHasType(p,
             db ? (MEMTYPE_DB|MEMTYPE_HEAP) : MEMTYPE_HEAP) );
    return sqlite3GlobalConfig.m.xSize(p);
  }
}

/*
** Free memory previously obtained from sqlite3Malloc().
*/
SQLITE_API void sqlite3_free(void *p){
  if( p==0 ) return;
  assert( sqlite3MemdebugHasType(p, MEMTYPE_HEAP) );
  if( sqlite3GlobalConfig.bMemstat ){
    sqlite3_mutex_enter(mem0.mutex);
    sqlite3StatusAdd(SQLITE_STATUS_MEMORY_USED, -sqlite3MallocSize(p));
    sqlite3GlobalConfig.m.xFree(p);
    sqlite3_mutex_leave(mem0.mutex);
  }else{
    sqlite3GlobalConfig.m.xFree(p);

  assert( db==0 || sqlite3_mutex_held(db->mutex) );
  if( isLookaside(db, p) ){
    LookasideSlot *pBuf = (LookasideSlot*)p;
    pBuf->pNext = db->lookaside.pFree;
    db->lookaside.pFree = pBuf;
    db->lookaside.nOut--;
  }else{
    assert( sqlite3MemdebugHasType(p, MEMTYPE_DB|MEMTYPE_HEAP) );
    sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
    sqlite3_free(p);
  }
}

/*
** Change the size of an existing memory allocation
*/

  }else if( sqlite3GlobalConfig.bMemstat ){
    sqlite3_mutex_enter(mem0.mutex);
    sqlite3StatusSet(SQLITE_STATUS_MALLOC_SIZE, nBytes);
    if( sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED)+nNew-nOld >= 
          mem0.alarmThreshold ){
      sqlite3MallocAlarm(nNew-nOld);
    }
    assert( sqlite3MemdebugHasType(pOld, MEMTYPE_HEAP) );
    pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
    if( pNew==0 && mem0.alarmCallback ){
      sqlite3MallocAlarm(nBytes);
      pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
    }
    if( pNew ){
      nNew = sqlite3MallocSize(pNew);

    return 0;
  }
#endif
  p = sqlite3Malloc(n);
  if( !p && db ){
    db->mallocFailed = 1;
  }
  sqlite3MemdebugSetType(p,
            (db && db->lookaside.bEnabled) ? MEMTYPE_DB : MEMTYPE_HEAP);
  return p;
}

/*
** Resize the block of memory pointed to by p to n bytes. If the
** resize fails, set the mallocFailed flag in the connection object.
*/

      }
      pNew = sqlite3DbMallocRaw(db, n);
      if( pNew ){
        memcpy(pNew, p, db->lookaside.sz);
        sqlite3DbFree(db, p);
      }
    }else{
      assert( sqlite3MemdebugHasType(p, MEMTYPE_DB|MEMTYPE_HEAP) );
      sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
      pNew = sqlite3_realloc(p, n);
      if( !pNew ){
        db->mallocFailed = 1;
      }
      sqlite3MemdebugSetType(pNew,
            db->lookaside.bEnabled ? MEMTYPE_DB : MEMTYPE_HEAP);
    }
  }
  return pNew;
}

/*
** Attempt to reallocate p.  If the reallocation fails, then free p

  u8 usesStmtJournal;     /* True if uses a statement journal */
  u8 readOnly;            /* True for read-only statements */
  u8 isPrepareV2;         /* True if prepared with prepare_v2() */
  int nChange;            /* Number of db changes made since last reset */
  int btreeMask;          /* Bitmask of db->aDb[] entries referenced */
  i64 startTime;          /* Time when query started - used for profiling */
  BtreeMutexArray aMutex; /* An array of Btree used here and needing locks */
  int aCounter[3];        /* Counters used by sqlite3_stmt_status() */
  char *zSql;             /* Text of the SQL statement that generated this */
  void *pFree;            /* Free this when deleting the vdbe */
  i64 nFkConstraint;      /* Number of imm. FK constraints this VM */
  i64 nStmtDefCons;       /* Number of def. constraints when stmt started */
  int iStatement;         /* Statement number (or 0 if has not opened stmt) */
#ifdef SQLITE_DEBUG
  FILE *trace;            /* Write an execution trace here, if not NULL */

     /*  33 */ "AutoCommit",
     /*  34 */ "Transaction",
     /*  35 */ "ReadCookie",
     /*  36 */ "SetCookie",
     /*  37 */ "VerifyCookie",
     /*  38 */ "OpenRead",
     /*  39 */ "OpenWrite",
     /*  40 */ "OpenAutoindex",
     /*  41 */ "OpenEphemeral",
     /*  42 */ "OpenPseudo",
     /*  43 */ "Close",
     /*  44 */ "SeekLt",
     /*  45 */ "SeekLe",
     /*  46 */ "SeekGe",
     /*  47 */ "SeekGt",
     /*  48 */ "Seek",
     /*  49 */ "NotFound",
     /*  50 */ "Found",
     /*  51 */ "IsUnique",
     /*  52 */ "NotExists",
     /*  53 */ "Sequence",
     /*  54 */ "NewRowid",
     /*  55 */ "Insert",
     /*  56 */ "InsertInt",
     /*  57 */ "Delete",
     /*  58 */ "ResetCount",
     /*  59 */ "RowKey",
     /*  60 */ "RowData",
     /*  61 */ "Rowid",
     /*  62 */ "NullRow",
     /*  63 */ "Last",
     /*  64 */ "Sort",
     /*  65 */ "Rewind",
     /*  66 */ "Prev",
     /*  67 */ "Next",
     /*  68 */ "Or",
     /*  69 */ "And",
     /*  70 */ "IdxInsert",
     /*  71 */ "IdxDelete",
     /*  72 */ "IdxRowid",
     /*  73 */ "IsNull",
     /*  74 */ "NotNull",
     /*  75 */ "Ne",
     /*  76 */ "Eq",
     /*  77 */ "Gt",
     /*  78 */ "Le",
     /*  79 */ "Lt",
     /*  80 */ "Ge",
     /*  81 */ "IdxLT",
     /*  82 */ "BitAnd",
     /*  83 */ "BitOr",
     /*  84 */ "ShiftLeft",
     /*  85 */ "ShiftRight",
     /*  86 */ "Add",
     /*  87 */ "Subtract",
     /*  88 */ "Multiply",
     /*  89 */ "Divide",
     /*  90 */ "Remainder",
     /*  91 */ "Concat",
     /*  92 */ "IdxGE",
     /*  93 */ "BitNot",
     /*  94 */ "String8",
     /*  95 */ "Destroy",
     /*  96 */ "Clear",
     /*  97 */ "CreateIndex",
     /*  98 */ "CreateTable",
     /*  99 */ "ParseSchema",
     /* 100 */ "LoadAnalysis",
     /* 101 */ "DropTable",
     /* 102 */ "DropIndex",
     /* 103 */ "DropTrigger",
     /* 104 */ "IntegrityCk",
     /* 105 */ "RowSetAdd",
     /* 106 */ "RowSetRead",
     /* 107 */ "RowSetTest",
     /* 108 */ "Program",
     /* 109 */ "Param",
     /* 110 */ "FkCounter",
     /* 111 */ "FkIfZero",
     /* 112 */ "MemMax",
     /* 113 */ "IfPos",
     /* 114 */ "IfNeg",
     /* 115 */ "IfZero",
     /* 116 */ "AggStep",
     /* 117 */ "AggFinal",
     /* 118 */ "Vacuum",
     /* 119 */ "IncrVacuum",
     /* 120 */ "Expire",
     /* 121 */ "TableLock",
     /* 122 */ "VBegin",
     /* 123 */ "VCreate",
     /* 124 */ "VDestroy",
     /* 125 */ "VOpen",
     /* 126 */ "VFilter",
     /* 127 */ "VColumn",
     /* 128 */ "VNext",
     /* 129 */ "VRename",
     /* 130 */ "Real",
     /* 131 */ "VUpdate",
     /* 132 */ "Pagecount",
     /* 133 */ "Trace",
     /* 134 */ "Noop",
     /* 135 */ "Explain",
     /* 136 */ "NotUsed_136",
     /* 137 */ "NotUsed_137",
     /* 138 */ "NotUsed_138",
     /* 139 */ "NotUsed_139",
     /* 140 */ "NotUsed_140",
     /* 141 */ "ToText",
     /* 142 */ "ToBlob",

      flags &= ~(SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE);
      openFlags &= ~(O_RDWR|O_CREAT);
      flags |= SQLITE_OPEN_READONLY;
      openFlags |= O_RDONLY;
      fd = open(zName, openFlags, openMode);
    }
    if( fd<0 ){


      rc = SQLITE_CANTOPEN_BKPT;
      goto open_finished;
    }
  }
  assert( fd>=0 );
  if( pOutFlags ){
    *pOutFlags = flags;
  }

*/
SQLITE_PRIVATE void sqlite3PcacheTruncate(PCache *pCache, Pgno pgno){
  if( pCache->pCache ){
    PgHdr *p;
    PgHdr *pNext;
    for(p=pCache->pDirty; p; p=pNext){
      pNext = p->pDirtyNext;
      /* This routine never gets call with a positive pgno except right
      ** after sqlite3PcacheCleanAll().  So if there are dirty pages,
      ** it must be that pgno==0.
      */
      assert( p->pgno>0 );
      if( ALWAYS(p->pgno>pgno) ){
        assert( p->flags&PGHDR_DIRTY );
        sqlite3PcacheMakeClean(p);
      }
    }
    if( pgno==0 && pCache->pPage1 ){
      memset(pCache->pPage1->pData, 0, pCache->szPage);
      pgno = 1;

    pcache1LeaveMutex();
    p = sqlite3Malloc(nByte);
    pcache1EnterMutex();
    if( p ){
      int sz = sqlite3MallocSize(p);
      sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, sz);
    }
    sqlite3MemdebugSetType(p, MEMTYPE_PCACHE);
  }
  return p;
}

/*
** Free an allocated buffer obtained from pcache1Alloc().
*/
static void pcache1Free(void *p){
  assert( sqlite3_mutex_held(pcache1.mutex) );
  if( p==0 ) return;
  if( p>=pcache1.pStart && p<pcache1.pEnd ){
    PgFreeslot *pSlot;
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_USED, -1);
    pSlot = (PgFreeslot*)p;
    pSlot->pNext = pcache1.pFree;
    pcache1.pFree = pSlot;
  }else{
    int iSize;
    assert( sqlite3MemdebugHasType(p, MEMTYPE_PCACHE) );
    sqlite3MemdebugSetType(p, MEMTYPE_HEAP);
    iSize = sqlite3MallocSize(p);
    sqlite3StatusAdd(SQLITE_STATUS_PAGECACHE_OVERFLOW, -iSize);
    sqlite3_free(p);
  }
}

/*
** Allocate a new page object initially associated with cache pCache.

** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
*/
#ifndef SQLITE_OMIT_DISKIO

/*
******************** NOTES ON THE DESIGN OF THE PAGER ************************
**
** Within this comment block, a page is deemed to have been synced
** automatically as soon as it is written when PRAGMA synchronous=OFF.
** Otherwise, the page is not synced until the xSync method of the VFS
** is called successfully on the file containing the page.
**
** Definition:  A page of the database file is said to be "overwriteable" if
** one or more of the following are true about the page:
** 
**     (a)  The original content of the page as it was at the beginning of
**          the transaction has been written into the rollback journal and
**          synced.
** 
**     (b)  The page was a freelist leaf page at the start of the transaction.
** 
**     (c)  The page number is greater than the largest page that existed in
**          the database file at the start of the transaction.
** 
** (1) A page of the database file is never overwritten unless one of the
**     following are true:
** 
**     (a) The page and all other pages on the same sector are overwriteable.
** 
**     (b) The atomic page write optimization is enabled, and the entire
**         transaction other than the update of the transaction sequence
**         number consists of a single page change.
** 
** (2) The content of a page written into the rollback journal exactly matches
**     both the content in the database when the rollback journal was written
**     and the content in the database at the beginning of the current
**     transaction.
** 
** (3) Writes to the database file are an integer multiple of the page size
**     in length and are aligned to a page boundary.
** 
** (4) Reads from the database file are either aligned on a page boundary and
**     an integer multiple of the page size in length or are taken from the
**     first 100 bytes of the database file.
** 
** (5) All writes to the database file are synced prior to the rollback journal
**     being deleted, truncated, or zeroed.
** 
** (6) If a master journal file is used, then all writes to the database file
**     are synced prior to the master journal being deleted.
** 
** Definition: Two databases (or the same database at two points it time)
** are said to be "logically equivalent" if they give the same answer to
** all queries.  Note in particular the the content of freelist leaf
** pages can be changed arbitarily without effecting the logical equivalence
** of the database.
** 
** (7) At any time, if any subset, including the empty set and the total set,
**     of the unsynced changes to a rollback journal are removed and the 
**     journal is rolled back, the resulting database file will be logical
**     equivalent to the database file at the beginning of the transaction.
** 
** (8) When a transaction is rolled back, the xTruncate method of the VFS
**     is called to restore the database file to the same size it was at
**     the beginning of the transaction.  (In some VFSes, the xTruncate
**     method is a no-op, but that does not change the fact the SQLite will
**     invoke it.)
** 
** (9) Whenever the database file is modified, at least one bit in the range
**     of bytes from 24 through 39 inclusive will be changed prior to releasing
**     the EXCLUSIVE lock.
**
** (10) The pattern of bits in bytes 24 through 39 shall not repeat in less
**      than one billion transactions.
**
** (11) A database file is well-formed at the beginning and at the conclusion
**      of every transaction.
**
** (12) An EXCLUSIVE lock is held on the database file when writing to
**      the database file.
**
** (13) A SHARED lock is held on the database file while reading any
**      content out of the database file.
*/

/*
** Macros for troubleshooting.  Normally turned off
*/
#if 0
int sqlite3PagerTrace=1;  /* True to enable tracing */
#define sqlite3DebugPrintf printf
#define PAGERTRACE(X)     if( sqlite3PagerTrace ){ sqlite3DebugPrintf X; }

**   It is cleared at the end of each transaction.
**
**   It is used when committing or otherwise ending a transaction. If
**   the dbModified flag is clear then less work has to be done.
**
** journalStarted
**
**   This flag is set whenever the the main journal is opened and
**   initialized
**
**   The point of this flag is that it must be set after the 
**   first journal header in a journal file has been synced to disk.
**   After this has happened, new pages appended to the database 
**   do not need the PGHDR_NEED_SYNC flag set, as they do not need
**   to wait for a journal sync before they can be written out to
**   the database file (see function pager_write()).

**   may attempt to commit the transaction again later (calling
**   CommitPhaseOne() again). This flag is used to ensure that the 
**   master journal name is only written to the journal file the first
**   time CommitPhaseOne() is called.
**
** doNotSync
**
**   When enabled, cache spills are prohibited and the journal file cannot
**   be synced.  This variable is set and cleared by sqlite3PagerWrite() 
**   in order to prevent a journal sync from happening in between the
**   journalling of two pages on the same sector.
**
** needSync
**
**   TODO: It might be easier to set this variable in writeJournalHdr()
**   and writeMasterJournal() only. Change its meaning to "unsynced data
**   has been written to the journal".
**

  u32 nSubRec;                /* Number of records written to sub-journal */
  Bitvec *pInJournal;         /* One bit for each page in the database file */
  sqlite3_file *fd;           /* File descriptor for database */
  sqlite3_file *jfd;          /* File descriptor for main journal */
  sqlite3_file *sjfd;         /* File descriptor for sub-journal */
  i64 journalOff;             /* Current write offset in the journal file */
  i64 journalHdr;             /* Byte offset to previous journal header */
  i64 journalSizeLimit;       /* Size limit for persistent journal files */
  PagerSavepoint *aSavepoint; /* Array of active savepoints */
  int nSavepoint;             /* Number of elements in aSavepoint[] */
  char dbFileVers[16];        /* Changes whenever database file changes */
  u32 sectorSize;             /* Assumed sector size during rollback */

  u16 nExtra;                 /* Add this many bytes to each in-memory page */
  i16 nReserve;               /* Number of unused bytes at end of each page */

#ifdef SQLITE_HAS_CODEC
  void *(*xCodec)(void*,void*,Pgno,int); /* Routine for en/decoding data */
  void (*xCodecSizeChng)(void*,int,int); /* Notify of page size changes */
  void (*xCodecFree)(void*);             /* Destructor for the codec */
  void *pCodec;               /* First argument to xCodec... methods */
#endif
  char *pTmpSpace;            /* Pager.pageSize bytes of space for tmp use */

  PCache *pPCache;            /* Pointer to page cache object */
  sqlite3_backup *pBackup;    /* Pointer to list of ongoing backup processes */
};

/*
** The following global variables hold counters used for
** testing purposes only.  These variables do not exist in

  ** database page size. Since the zHeader buffer is only Pager.pageSize
  ** bytes in size, more than one call to sqlite3OsWrite() may be required
  ** to populate the entire journal header sector.
  */ 
  for(nWrite=0; rc==SQLITE_OK&&nWrite<JOURNAL_HDR_SZ(pPager); nWrite+=nHeader){
    IOTRACE(("JHDR %p %lld %d\n", pPager, pPager->journalHdr, nHeader))
    rc = sqlite3OsWrite(pPager->jfd, zHeader, nHeader, pPager->journalOff);
    assert( pPager->journalHdr <= pPager->journalOff );
    pPager->journalOff += nHeader;
  }

  return rc;
}

/*

   || pPager->journalMode==PAGER_JOURNALMODE_MEMORY 
   || pPager->journalMode==PAGER_JOURNALMODE_OFF 
  ){
    return SQLITE_OK;
  }
  pPager->setMaster = 1;
  assert( isOpen(pPager->jfd) );
  assert( pPager->journalHdr <= pPager->journalOff );

  /* Calculate the length in bytes and the checksum of zMaster */
  for(nMaster=0; zMaster[nMaster]; nMaster++){
    cksum += zMaster[nMaster];
  }

  /* If in full-sync mode, advance to the next disk sector before writing

    sqlite3OsClose(pPager->jfd);
    sqlite3BitvecDestroy(pPager->pInJournal);
    pPager->pInJournal = 0;
    releaseAllSavepoints(pPager);

    /* If the file is unlocked, somebody else might change it. The
    ** values stored in Pager.dbSize etc. might become invalid if
    ** this happens.  One can argue that this doesn't need to be cleared
    ** until the change-counter check fails in PagerSharedLock().
    ** Clearing the page size cache here is being conservative.
    */
    pPager->dbSizeValid = 0;

    rc = osUnlock(pPager->fd, NO_LOCK);
    if( rc ){
      pPager->errCode = rc;
    }

        rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
      }
    }

#ifdef SQLITE_CHECK_PAGES
    sqlite3PcacheIterateDirty(pPager->pPCache, pager_set_pagehash);
#endif
  }

  sqlite3BitvecDestroy(pPager->pInJournal);
  pPager->pInJournal = 0;
  pPager->nRec = 0;

  sqlite3PcacheCleanAll(pPager->pPCache);

  if( !pPager->exclusiveMode ){
    rc2 = osUnlock(pPager->fd, SHARED_LOCK);
    pPager->state = PAGER_SHARED;
    pPager->changeCountDone = 0;
  }else if( pPager->state==PAGER_SYNCED ){
    pPager->state = PAGER_EXCLUSIVE;

**
** If this is a savepoint rollback, then memory may have to be dynamically
** allocated by this function. If this is the case and an allocation fails,
** SQLITE_NOMEM is returned.
*/
static int pager_playback_one_page(
  Pager *pPager,                /* The pager being played back */


  i64 *pOffset,                 /* Offset of record to playback */

  Bitvec *pDone,                /* Bitvec of pages already played back */
  int isMainJrnl,               /* 1 -> main journal. 0 -> sub-journal. */
  int isSavepnt                 /* True for a savepoint rollback */
){
  int rc;
  PgHdr *pPg;                   /* An existing page in the cache */
  Pgno pgno;                    /* The page number of a page in journal */
  u32 cksum;                    /* Checksum used for sanity checking */
  char *aData;                  /* Temporary storage for the page */
  sqlite3_file *jfd;            /* The file descriptor for the journal file */
  int isSynced;                 /* True if journal page is synced */

  assert( (isMainJrnl&~1)==0 );      /* isMainJrnl is 0 or 1 */
  assert( (isSavepnt&~1)==0 );       /* isSavepnt is 0 or 1 */
  assert( isMainJrnl || pDone );     /* pDone always used on sub-journals */
  assert( isSavepnt || pDone==0 );   /* pDone never used on non-savepoint */

  aData = pPager->pTmpSpace;

  */
  pPg = pager_lookup(pPager, pgno);
  assert( pPg || !MEMDB );
  PAGERTRACE(("PLAYBACK %d page %d hash(%08x) %s\n",
           PAGERID(pPager), pgno, pager_datahash(pPager->pageSize, (u8*)aData),
           (isMainJrnl?"main-journal":"sub-journal")
  ));
  if( isMainJrnl ){
    isSynced = pPager->noSync || (*pOffset <= pPager->journalHdr);
  }else{
    isSynced = (pPg==0 || 0==(pPg->flags & PGHDR_NEED_SYNC));
  }
  if( (pPager->state>=PAGER_EXCLUSIVE)

   && isOpen(pPager->fd)
   && isSynced
  ){
    i64 ofst = (pgno-1)*(i64)pPager->pageSize;
    testcase( !isSavepnt && pPg!=0 && (pPg->flags&PGHDR_NEED_SYNC)!=0 );
    rc = sqlite3OsWrite(pPager->fd, (u8*)aData, pPager->pageSize, ofst);
    if( pgno>pPager->dbFileSize ){
      pPager->dbFileSize = pgno;
    }
    if( pPager->pBackup ){
      CODEC1(pPager, aData, pgno, 3, rc=SQLITE_NOMEM);
      sqlite3BackupUpdate(pPager->pBackup, pgno, (u8*)aData);

    pData = pPg->pData;
    memcpy(pData, (u8*)aData, pPager->pageSize);
    pPager->xReiniter(pPg);
    if( isMainJrnl && (!isSavepnt || *pOffset<=pPager->journalHdr) ){
      /* If the contents of this page were just restored from the main 
      ** journal file, then its content must be as they were when the 
      ** transaction was first opened. In this case we can mark the page
      ** as clean, since there will be no need to write it out to the
      ** database.
      **
      ** There is one exception to this rule. If the page is being rolled
      ** back as part of a savepoint (or statement) rollback from an 
      ** unsynced portion of the main journal file, then it is not safe
      ** to mark the page as clean. This is because marking the page as
      ** clean will clear the PGHDR_NEED_SYNC flag. Since the page is
      ** already in the journal file (recorded in Pager.pInJournal) and

  needPagerReset = isHot;

  /* This loop terminates either when a readJournalHdr() or 
  ** pager_playback_one_page() call returns SQLITE_DONE or an IO error 
  ** occurs. 
  */
  while( 1 ){


    /* Read the next journal header from the journal file.  If there are
    ** not enough bytes left in the journal file for a complete header, or
    ** it is corrupted, then a process must of failed while writing it.
    ** This indicates nothing more needs to be rolled back.
    */
    rc = readJournalHdr(pPager, isHot, szJ, &nRec, &mxPg);
    if( rc!=SQLITE_OK ){ 

    ** the journal, it means that the journal might contain additional
    ** pages that need to be rolled back and that the number of pages 
    ** should be computed based on the journal file size.
    */
    if( nRec==0 && !isHot &&
        pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff ){
      nRec = (int)((szJ - pPager->journalOff) / JOURNAL_PG_SZ(pPager));

    }

    /* If this is the first header read from the journal, truncate the
    ** database file back to its original size.
    */
    if( pPager->journalOff==JOURNAL_HDR_SZ(pPager) ){
      rc = pager_truncate(pPager, mxPg);

    ** database file and/or page cache.
    */
    for(u=0; u<nRec; u++){
      if( needPagerReset ){
        pager_reset(pPager);
        needPagerReset = 0;
      }
      rc = pager_playback_one_page(pPager,&pPager->journalOff,0,1,0);
      if( rc!=SQLITE_OK ){
        if( rc==SQLITE_DONE ){
          rc = SQLITE_OK;
          pPager->journalOff = szJ;
          break;
        }else if( rc==SQLITE_IOERR_SHORT_READ ){
          /* If the journal has been truncated, simply stop reading and
          ** processing the journal. This might happen if the journal was
          ** not completely written and synced prior to a crash.  In that
          ** case, the database should have never been written in the
          ** first place so it is OK to simply abandon the rollback. */
          rc = SQLITE_OK;
          goto end_playback;
        }else{
          /* If we are unable to rollback, quit and return the error
          ** code.  This will cause the pager to enter the error state
          ** so that no further harm will be done.  Perhaps the next
          ** process to come along will be able to rollback the database.
          */
          goto end_playback;

  ** will be skipped automatically.  Pages are added to pDone as they
  ** are played back.
  */
  if( pSavepoint ){
    iHdrOff = pSavepoint->iHdrOffset ? pSavepoint->iHdrOffset : szJ;
    pPager->journalOff = pSavepoint->iOffset;
    while( rc==SQLITE_OK && pPager->journalOff<iHdrOff ){
      rc = pager_playback_one_page(pPager, &pPager->journalOff, pDone, 1, 1);
    }
    assert( rc!=SQLITE_DONE );
  }else{
    pPager->journalOff = 0;
  }

  /* Continue rolling back records out of the main journal starting at

    */
    if( nJRec==0 
     && pPager->journalHdr+JOURNAL_HDR_SZ(pPager)==pPager->journalOff
    ){
      nJRec = (u32)((szJ - pPager->journalOff)/JOURNAL_PG_SZ(pPager));
    }
    for(ii=0; rc==SQLITE_OK && ii<nJRec && pPager->journalOff<szJ; ii++){
      rc = pager_playback_one_page(pPager, &pPager->journalOff, pDone, 1, 1);
    }
    assert( rc!=SQLITE_DONE );
  }
  assert( rc!=SQLITE_OK || pPager->journalOff==szJ );

  /* Finally,  rollback pages from the sub-journal.  Page that were
  ** previously rolled back out of the main journal (and are hence in pDone)
  ** will be skipped.  Out-of-range pages are also skipped.
  */
  if( pSavepoint ){
    u32 ii;            /* Loop counter */
    i64 offset = pSavepoint->iSubRec*(4+pPager->pageSize);
    for(ii=pSavepoint->iSubRec; rc==SQLITE_OK && ii<pPager->nSubRec; ii++){
      assert( offset==ii*(4+pPager->pageSize) );
      rc = pager_playback_one_page(pPager, &offset, pDone, 0, 1);
    }
    assert( rc!=SQLITE_DONE );
  }

  sqlite3BitvecDestroy(pDone);
  if( rc==SQLITE_OK ){
    pPager->journalOff = szJ;

** Attempt to set the maximum database page count if mxPage is positive. 
** Make no changes if mxPage is zero or negative.  And never reduce the
** maximum page count below the current size of the database.
**
** Regardless of mxPage, return the current maximum page count.
*/
SQLITE_PRIVATE int sqlite3PagerMaxPageCount(Pager *pPager, int mxPage){
  int nPage;
  if( mxPage>0 ){
    pPager->mxPgno = mxPage;
  }
  sqlite3PagerPagecount(pPager, &nPage);
  assert( pPager->mxPgno>=nPage );
  return pPager->mxPgno;
}

/*
** The following set of routines are used to disable the simulated
** I/O error mechanism.  These routines are used to avoid simulated
** errors in places where we do not care about errors.

**
** Otherwise, if everything is successful, then SQLITE_OK is returned
** and *pnPage is set to the number of pages in the database.
*/
SQLITE_PRIVATE int sqlite3PagerPagecount(Pager *pPager, int *pnPage){
  Pgno nPage;               /* Value to return via *pnPage */






  /* Determine the number of pages in the file. Store this in nPage. */
  if( pPager->dbSizeValid ){
    nPage = pPager->dbSize;
  }else{
    int rc;                 /* Error returned by OsFileSize() */
    i64 n = 0;              /* File size in bytes returned by OsFileSize() */

  ** that the file can be read.
  */
  if( nPage>pPager->mxPgno ){
    pPager->mxPgno = (Pgno)nPage;
  }

  /* Set the output variable and return SQLITE_OK */

  *pnPage = nPage;

  return SQLITE_OK;
}


/*
** Try to obtain a lock of type locktype on the database file. If
** a similar or greater lock is already held, this function is a no-op

SQLITE_PRIVATE void sqlite3PagerTruncateImage(Pager *pPager, Pgno nPage){
  assert( pPager->dbSizeValid );
  assert( pPager->dbSize>=nPage );
  assert( pPager->state>=PAGER_RESERVED );
  pPager->dbSize = nPage;
  assertTruncateConstraint(pPager);
}

/*
** This function is called before attempting a hot-journal rollback. It
** syncs the journal file to disk, then sets pPager->journalHdr to the
** size of the journal file so that the pager_playback() routine knows
** that the entire journal file has been synced.
**
** Syncing a hot-journal to disk before attempting to roll it back ensures 
** that if a power-failure occurs during the rollback, the process that
** attempts rollback following system recovery sees the same journal
** content as this process.
**
** If everything goes as planned, SQLITE_OK is returned. Otherwise, 
** an SQLite error code.
*/
static int pagerSyncHotJournal(Pager *pPager){
  int rc = SQLITE_OK;
  if( !pPager->noSync ){
    rc = sqlite3OsSync(pPager->jfd, SQLITE_SYNC_NORMAL);
  }
  if( rc==SQLITE_OK ){
    rc = sqlite3OsFileSize(pPager->jfd, &pPager->journalHdr);
  }
  return rc;
}

/*
** Shutdown the page cache.  Free all memory and close all files.
**
** If a transaction was in progress when this routine is called, that
** transaction is rolled back.  All outstanding pages are invalidated
** and their memory is freed.  Any attempt to use a page associated

  }else{
    /* Set Pager.journalHdr to -1 for the benefit of the pager_playback() 
    ** call which may be made from within pagerUnlockAndRollback(). If it
    ** is not -1, then the unsynced portion of an open journal file may
    ** be played back into the database. If a power failure occurs while
    ** this is happening, the database may become corrupt.
    */
    if( isOpen(pPager->jfd) ){
      pPager->errCode = pagerSyncHotJournal(pPager);
    }
    pagerUnlockAndRollback(pPager);
  }
  sqlite3EndBenignMalloc();
  enable_simulated_io_errors();
  PAGERTRACE(("CLOSE %d\n", PAGERID(pPager)));
  IOTRACE(("CLOSE %p\n", pPager))
  sqlite3OsClose(pPager->fd);

      if( 0==(iDc&SQLITE_IOCAP_SAFE_APPEND) ){
        /* This block deals with an obscure problem. If the last connection
        ** that wrote to this database was operating in persistent-journal
        ** mode, then the journal file may at this point actually be larger
        ** than Pager.journalOff bytes. If the next thing in the journal
        ** file happens to be a journal-header (written as part of the
        ** previous connection's transaction), and a crash or power-failure 
        ** occurs after nRec is updated but before this connection writes 
        ** anything else to the journal file (or commits/rolls back its 
        ** transaction), then SQLite may become confused when doing the 
        ** hot-journal rollback following recovery. It may roll back all
        ** of this connections data, then proceed to rolling back the old,
        ** out-of-date data that follows it. Database corruption.
        **

    }

    /* The journal file was just successfully synced. Set Pager.needSync 
    ** to zero and clear the PGHDR_NEED_SYNC flag on all pagess.
    */
    pPager->needSync = 0;
    pPager->journalStarted = 1;
    pPager->journalHdr = pPager->journalOff;
    sqlite3PcacheClearSyncFlags(pPager->pPCache);
  }

  return SQLITE_OK;
}

/*

          }
        }
      }
      if( rc!=SQLITE_OK ){
        goto failed;
      }

      /* Reset the journal status fields to indicates that we have no
      ** rollback journal at this time. */
      pPager->journalStarted = 0;
      pPager->journalOff = 0;
      pPager->setMaster = 0;
      pPager->journalHdr = 0;

      /* Make sure the journal file has been synced to disk. */
 
      /* Playback and delete the journal.  Drop the database write
      ** lock and reacquire the read lock. Purge the cache before
      ** playing back the hot-journal so that we don't end up with
      ** an inconsistent cache.  Sync the hot journal before playing
      ** it back since the process that crashed and left the hot journal
      ** probably did not sync it and we are required to always sync
      ** the journal before playing it back.
      */
      if( isOpen(pPager->jfd) ){
        rc = pagerSyncHotJournal(pPager);
        if( rc==SQLITE_OK ){
          rc = pager_playback(pPager, 1);
        }
        if( rc!=SQLITE_OK ){
          rc = pager_error(pPager, rc);
          goto failed;
        }
      }
      assert( (pPager->state==PAGER_SHARED)
           || (pPager->exclusiveMode && pPager->state>PAGER_SHARED)

      ** other bytes change randomly with each file change when
      ** a codec is in use.
      ** 
      ** There is a vanishingly small chance that a change will not be 
      ** detected.  The chance of an undetected change is so small that
      ** it can be neglected.
      */
      int nPage;
      char dbFileVers[sizeof(pPager->dbFileVers)];
      sqlite3PagerPagecount(pPager, &nPage);

      if( pPager->errCode ){
        rc = pPager->errCode;
        goto failed;
      }


      if( nPage>0 ){
        IOTRACE(("CKVERS %p %d\n", pPager, sizeof(dbFileVers)));
        rc = sqlite3OsRead(pPager->fd, &dbFileVers, sizeof(dbFileVers), 24);
        if( rc!=SQLITE_OK ){
          goto failed;
        }
      }else{
        memset(dbFileVers, 0, sizeof(dbFileVers));

**
** If noContent is true, it means that we do not care about the contents
** of the page. This occurs in two seperate scenarios:
**
**   a) When reading a free-list leaf page from the database, and
**
**   b) When a savepoint is being rolled back and we need to load
**      a new page into the cache to be filled with the data read
**      from the savepoint journal.
**
** If noContent is true, then the data returned is zeroed instead of
** being read from the database. Additionally, the bits corresponding
** to pgno in Pager.pInJournal (bitvec of pages already written to the
** journal file) and the PagerSavepoint.pInSavepoint bitvecs of any open
** savepoints are set. This means if the page is made writable at any

    ** Set pPg to 0 and jump to the exception handler.  */
    pPg = 0;
    goto pager_acquire_err;
  }
  assert( (*ppPage)->pgno==pgno );
  assert( (*ppPage)->pPager==pPager || (*ppPage)->pPager==0 );

  if( (*ppPage)->pPager && !noContent ){
    /* In this case the pcache already contains an initialized copy of
    ** the page. Return without further ado.  */
    assert( pgno<=PAGER_MAX_PGNO && pgno!=PAGER_MJ_PGNO(pPager) );
    PAGER_INCR(pPager->nHit);
    return SQLITE_OK;

  }else{

**
** Return SQLITE_OK if everything is successful. Otherwise, return 
** SQLITE_NOMEM if the attempt to allocate Pager.pInJournal fails, or 
** an IO error code if opening or writing the journal file fails.
*/
static int pager_open_journal(Pager *pPager){
  int rc = SQLITE_OK;                        /* Return code */
  int nPage;                                 /* Size of database file */
  sqlite3_vfs * const pVfs = pPager->pVfs;   /* Local cache of vfs pointer */

  assert( pPager->state>=PAGER_RESERVED );
  assert( pPager->useJournal );
  assert( pPager->journalMode!=PAGER_JOURNALMODE_OFF );
  assert( pPager->pInJournal==0 );
  
  /* If already in the error state, this function is a no-op.  But on
  ** the other hand, this routine is never called if we are already in
  ** an error state. */
  if( NEVER(pPager->errCode) ) return pPager->errCode;




  testcase( pPager->dbSizeValid==0 );
  rc = sqlite3PagerPagecount(pPager, &nPage);
  if( rc ) return rc;
  pPager->pInJournal = sqlite3BitvecCreate(nPage);
  if( pPager->pInJournal==0 ){
    return SQLITE_NOMEM;
  }

  /* Open the journal file if it is not already open. */
  if( !isOpen(pPager->jfd) ){
    if( pPager->journalMode==PAGER_JOURNALMODE_MEMORY ){

    if( rc==SQLITE_OK ){
      pPager->state = PAGER_RESERVED;
      if( exFlag ){
        rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);
      }
    }

    /* No need to open the journal file at this time.  It will be
    ** opened before it is written to.  If we defer opening the journal,
    ** we might save the work of creating a file if the transaction
    ** ends up being a no-op.
    */



  }else if( isOpen(pPager->jfd) && pPager->journalOff==0 ){
    /* This happens when the pager was in exclusive-access mode the last
    ** time a (read or write) transaction was successfully concluded
    ** by this connection. Instead of deleting the journal file it was 
    ** kept open and either was truncated to 0 bytes or its header was
    ** overwritten with zeros.
    */
    assert( pPager->nRec==0 );
    assert( pPager->dbOrigSize==0 );
    assert( pPager->pInJournal==0 );
    rc = pager_open_journal(pPager);
  }

  PAGERTRACE(("TRANSACTION %d\n", PAGERID(pPager)));

  if( rc!=SQLITE_OK ){
    assert( !pPager->dbModified );
    /* Ignore any IO error that occurs within pager_end_transaction(). The
    ** purpose of this call is to reset the internal state of the pager
    ** sub-system. It doesn't matter if the journal-file is not properly
    ** finalized at this point (since it is not a valid journal file anyway).
    */

  int rc = SQLITE_OK;

  /* This routine is not called unless a transaction has already been
  ** started.
  */
  assert( pPager->state>=PAGER_RESERVED );

  /* If an error has been previously detected, report the same error
  ** again.
  */
  if( NEVER(pPager->errCode) )  return pPager->errCode;

  /* Higher-level routines never call this function if database is not
  ** writable.  But check anyway, just for robustness. */
  if( NEVER(pPager->readOnly) ) return SQLITE_PERM;

  }else{

    /* If we get this far, it means that the page needs to be
    ** written to the transaction journal or the ckeckpoint journal
    ** or both.
    **
    ** Higher level routines should have already started a transaction,
    ** which means they have acquired the necessary locks but the rollback
    ** journal might not yet be open.
    */
    rc = sqlite3PagerBegin(pPager, 0, pPager->subjInMemory);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    if( !isOpen(pPager->jfd) && pPager->journalMode!=PAGER_JOURNALMODE_OFF ){
      assert( pPager->useJournal );
      rc = pager_open_journal(pPager);
      if( rc!=SQLITE_OK ) return rc;
    }

        u32 cksum;
        char *pData2;

        /* We should never write to the journal file the page that
        ** contains the database locks.  The following assert verifies
        ** that we do not. */
        assert( pPg->pgno!=PAGER_MJ_PGNO(pPager) );

        assert( pPager->journalHdr <= pPager->journalOff );
        CODEC2(pPager, pData, pPg->pgno, 7, return SQLITE_NOMEM, pData2);
        cksum = pager_cksum(pPager, (u8*)pData2);
        rc = write32bits(pPager->jfd, pPager->journalOff, pPg->pgno);
        if( rc==SQLITE_OK ){
          rc = sqlite3OsWrite(pPager->jfd, pData2, pPager->pageSize,
                              pPager->journalOff + 4);
          pPager->journalOff += pPager->pageSize+4;

    /* This trick assumes that both the page-size and sector-size are
    ** an integer power of 2. It sets variable pg1 to the identifier
    ** of the first page of the sector pPg is located on.
    */
    pg1 = ((pPg->pgno-1) & ~(nPagePerSector-1)) + 1;

    rc = sqlite3PagerPagecount(pPager, (int *)&nPageCount);
    if( rc ) return rc;
    if( pPg->pgno>nPageCount ){
      nPage = (pPg->pgno - pg1)+1;
    }else if( (pg1+nPagePerSector-1)>nPageCount ){
      nPage = nPageCount+1-pg1;
    }else{
      nPage = nPagePerSector;
    }

    if( rc==SQLITE_OK ){
      /* Increment the value just read and write it back to byte 24. */
      change_counter = sqlite3Get4byte((u8*)pPager->dbFileVers);
      change_counter++;
      put32bits(((char*)pPgHdr->pData)+24, change_counter);

      /* Also store the SQLite version number in bytes 96..99 */
      put32bits(((char*)pPgHdr->pData)+96, SQLITE_VERSION_NUMBER);

      /* If running in direct mode, write the contents of page 1 to the file. */
      if( DIRECT_MODE ){
        const void *zBuf = pPgHdr->pData;
        assert( pPager->dbFileSize>0 );
        rc = sqlite3OsWrite(pPager->fd, zBuf, pPager->pageSize, 0);
        if( rc==SQLITE_OK ){
          pPager->changeCountDone = 1;

  int noSync                      /* True to omit the xSync on the db file */
){
  int rc = SQLITE_OK;             /* Return code */

  /* The dbOrigSize is never set if journal_mode=OFF */
  assert( pPager->journalMode!=PAGER_JOURNALMODE_OFF || pPager->dbOrigSize==0 );

  /* If a prior error occurred, report that error again. */


  if( NEVER(pPager->errCode) ) return pPager->errCode;

  PAGERTRACE(("DATABASE SYNC: File=%s zMaster=%s nSize=%d\n", 
      pPager->zFilename, zMaster, pPager->dbSize));

  if( MEMDB && pPager->dbModified ){
    /* If this is an in-memory db, or no pages have been written to, or this

/*
** Return the number of references to the pager.
*/
SQLITE_PRIVATE int sqlite3PagerRefcount(Pager *pPager){
  return sqlite3PcacheRefCount(pPager->pPCache);
}

/*
** Return the approximate number of bytes of memory currently
** used by the pager and its associated cache.
*/
SQLITE_PRIVATE int sqlite3PagerMemUsed(Pager *pPager){
  int perPageSize = pPager->pageSize + pPager->nExtra + 20;
  return perPageSize*sqlite3PcachePagecount(pPager->pPCache)
           + sqlite3MallocSize(pPager);
}

/*
** Return the number of references to the specified page.
*/
SQLITE_PRIVATE int sqlite3PagerPageRefcount(DbPage *pPage){
  return sqlite3PcachePageRefcount(pPage);
}

SQLITE_PRIVATE int sqlite3PagerOpenSavepoint(Pager *pPager, int nSavepoint){
  int rc = SQLITE_OK;                       /* Return code */
  int nCurrent = pPager->nSavepoint;        /* Current number of savepoints */

  if( nSavepoint>nCurrent && pPager->useJournal ){
    int ii;                                 /* Iterator variable */
    PagerSavepoint *aNew;                   /* New Pager.aSavepoint array */
    int nPage;                              /* Size of database file */



    rc = sqlite3PagerPagecount(pPager, &nPage);

    if( rc ) return rc;

    /* Grow the Pager.aSavepoint array using realloc(). Return SQLITE_NOMEM
    ** if the allocation fails. Otherwise, zero the new portion in case a 
    ** malloc failure occurs while populating it in the for(...) loop below.
    */
    aNew = (PagerSavepoint *)sqlite3Realloc(
        pPager->aSavepoint, sizeof(PagerSavepoint)*nSavepoint
    );
    if( !aNew ){
      return SQLITE_NOMEM;
    }
    memset(&aNew[nCurrent], 0, (nSavepoint-nCurrent) * sizeof(PagerSavepoint));
    pPager->aSavepoint = aNew;
    pPager->nSavepoint = nSavepoint;

    /* Populate the PagerSavepoint structures just allocated. */
    for(ii=nCurrent; ii<nSavepoint; ii++){

      aNew[ii].nOrig = nPage;
      if( isOpen(pPager->jfd) && pPager->journalOff>0 ){
        aNew[ii].iOffset = pPager->journalOff;
      }else{
        aNew[ii].iOffset = JOURNAL_HDR_SZ(pPager);
      }
      aNew[ii].iSubRec = pPager->nSubRec;
      aNew[ii].pInSavepoint = sqlite3BitvecCreate(nPage);
      if( !aNew[ii].pInSavepoint ){
        return SQLITE_NOMEM;
      }
    }

    /* Open the sub-journal, if it is not already opened. */
    rc = openSubJournal(pPager);

              || eMode==PAGER_JOURNALMODE_OFF)
   && !pPager->dbModified
   && (!isOpen(pPager->jfd) || 0==pPager->journalOff)
  ){
    if( isOpen(pPager->jfd) ){
      sqlite3OsClose(pPager->jfd);
    }
    assert( (PAGER_JOURNALMODE_TRUNCATE & 1)==1 );
    assert( (PAGER_JOURNALMODE_PERSIST & 1)==1 );
    assert( (PAGER_JOURNALMODE_DELETE & 1)==0 );
    assert( (PAGER_JOURNALMODE_MEMORY & 1)==0 );
    assert( (PAGER_JOURNALMODE_OFF & 1)==0 );
    if( (pPager->journalMode & 1)==1 && (eMode & 1)==0
         && !pPager->exclusiveMode ){
      sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
    }
    pPager->journalMode = (u8)eMode;
  }
  return (int)pPager->journalMode;
}

/*
** Get/set the size-limit used for persistent journal files.

  Pager *pPager;        /* The page cache */
  sqlite3 *db;          /* Database connection currently using this Btree */
  BtCursor *pCursor;    /* A list of all open cursors */
  MemPage *pPage1;      /* First page of the database */
  u8 readOnly;          /* True if the underlying file is readonly */
  u8 pageSizeFixed;     /* True if the page size can no longer be changed */
  u8 secureDelete;      /* True if secure_delete is enabled */
  u8 initiallyEmpty;    /* Database is empty at start of transaction */
#ifndef SQLITE_OMIT_AUTOVACUUM
  u8 autoVacuum;        /* True if auto-vacuum is enabled */
  u8 incrVacuum;        /* True if incr-vacuum is enabled */
#endif
  u16 pageSize;         /* Total number of bytes on a page */
  u16 usableSize;       /* Number of usable bytes on each page */
  u16 maxLocal;         /* Maximum local payload in non-LEAFDATA tables */
  u16 minLocal;         /* Minimum local payload in non-LEAFDATA tables */
  u16 maxLeaf;          /* Maximum local payload in a LEAFDATA table */
  u16 minLeaf;          /* Minimum local payload in a LEAFDATA table */
  u8 inTransaction;     /* Transaction state */
  int nTransaction;     /* Number of open transactions (read + write) */
  u32 nPage;            /* Number of pages in the database */
  void *pSchema;        /* Pointer to space allocated by sqlite3BtreeSchema() */
  void (*xFreeSchema)(void*);  /* Destructor for BtShared.pSchema */
  sqlite3_mutex *mutex; /* Non-recursive mutex required to access this struct */
  Bitvec *pHasContent;  /* Set of pages moved to free-list this transaction */
#ifndef SQLITE_OMIT_SHARED_CACHE
  int nRef;             /* Number of references to this structure */
  BtShared *pNext;      /* Next on a list of sharable BtShared structs */

** optimization 2 above is omitted if the corresponding bit is already
** set in BtShared.pHasContent. The contents of the bitvec are cleared
** at the end of every transaction.
*/
static int btreeSetHasContent(BtShared *pBt, Pgno pgno){
  int rc = SQLITE_OK;
  if( !pBt->pHasContent ){
    assert( pgno<=pBt->nPage );



    pBt->pHasContent = sqlite3BitvecCreate(pBt->nPage);
    if( !pBt->pHasContent ){
      rc = SQLITE_NOMEM;
    }
  }
  if( rc==SQLITE_OK && pgno<=sqlite3BitvecSize(pBt->pHasContent) ){
    rc = sqlite3BitvecSet(pBt->pHasContent, pgno);
  }

  return 0;
}

/*
** Return the size of the database file in pages. If there is any kind of
** error, return ((unsigned int)-1).
*/
static Pgno btreePagecount(BtShared *pBt){
  return pBt->nPage;

}
SQLITE_PRIVATE u32 sqlite3BtreeLastPage(Btree *p){
  assert( sqlite3BtreeHoldsMutex(p) );

  assert( ((p->pBt->nPage)&0x8000000)==0 );
  return (int)btreePagecount(p->pBt);
}

/*
** Get a page from the pager and initialize it.  This routine is just a
** convenience wrapper around separate calls to btreeGetPage() and 
** btreeInitPage().
**
** If an error occurs, then the value *ppPage is set to is undefined. It
** may remain unchanged, or it may be set to an invalid value.
*/
static int getAndInitPage(
  BtShared *pBt,          /* The database file */
  Pgno pgno,           /* Number of the page to get */
  MemPage **ppPage     /* Write the page pointer here */
){
  int rc;

  assert( sqlite3_mutex_held(pBt->mutex) );

  if( pgno<=0 || pgno>btreePagecount(pBt) ){
    return SQLITE_CORRUPT_BKPT;
  }
  rc = btreeGetPage(pBt, pgno, ppPage, 0);
  if( rc==SQLITE_OK ){
    rc = btreeInitPage(*ppPage);
    if( rc!=SQLITE_OK ){
      releasePage(*ppPage);
    }
  }









  return rc;
}

/*
** Release a MemPage.  This should be called once for each prior
** call to btreeGetPage.
*/

**
** SQLITE_OK is returned on success.  If the file is not a
** well-formed database file, then SQLITE_CORRUPT is returned.
** SQLITE_BUSY is returned if the database is locked.  SQLITE_NOMEM
** is returned if we run out of memory. 
*/
static int lockBtree(BtShared *pBt){
  int rc;              /* Result code from subfunctions */
  MemPage *pPage1;     /* Page 1 of the database file */
  int nPage;           /* Number of pages in the database */
  int nPageFile = 0;   /* Number of pages in the database file */
  int nPageHeader;     /* Number of pages in the database according to hdr */

  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( pBt->pPage1==0 );
  rc = sqlite3PagerSharedLock(pBt->pPager);
  if( rc!=SQLITE_OK ) return rc;
  rc = btreeGetPage(pBt, 1, &pPage1, 0);
  if( rc!=SQLITE_OK ) return rc;

  /* Do some checking to help insure the file we opened really is
  ** a valid database file. 
  */
  nPage = nPageHeader = get4byte(28+(u8*)pPage1->aData);
  if( (rc = sqlite3PagerPagecount(pBt->pPager, &nPageFile))!=SQLITE_OK ){;

    goto page1_init_failed;
  }
  if( nPage==0 ){
    nPage = nPageFile;
  }
  if( nPage>0 ){
    int pageSize;
    int usableSize;
    u8 *page1 = pPage1->aData;
    rc = SQLITE_NOTADB;
    if( memcmp(page1, zMagicHeader, 16)!=0 ){
      goto page1_init_failed;
    }

      pBt->usableSize = (u16)usableSize;
      pBt->pageSize = (u16)pageSize;
      freeTempSpace(pBt);
      rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize,
                                   pageSize-usableSize);
      return rc;
    }
    if( nPageHeader>nPageFile ){
      rc = SQLITE_CORRUPT_BKPT;
      goto page1_init_failed;
    }
    if( usableSize<480 ){
      goto page1_init_failed;
    }
    pBt->pageSize = (u16)pageSize;
    pBt->usableSize = (u16)usableSize;
#ifndef SQLITE_OMIT_AUTOVACUUM
    pBt->autoVacuum = (get4byte(&page1[36 + 4*4])?1:0);

  */
  pBt->maxLocal = (pBt->usableSize-12)*64/255 - 23;
  pBt->minLocal = (pBt->usableSize-12)*32/255 - 23;
  pBt->maxLeaf = pBt->usableSize - 35;
  pBt->minLeaf = (pBt->usableSize-12)*32/255 - 23;
  assert( pBt->maxLeaf + 23 <= MX_CELL_SIZE(pBt) );
  pBt->pPage1 = pPage1;
  pBt->nPage = nPage;
  return SQLITE_OK;

page1_init_failed:
  releasePage(pPage1);
  pBt->pPage1 = 0;
  return rc;
}

** into a new empty database by initializing the first page of
** the database.
*/
static int newDatabase(BtShared *pBt){
  MemPage *pP1;
  unsigned char *data;
  int rc;


  assert( sqlite3_mutex_held(pBt->mutex) );

  if( pBt->nPage>0 ){
    return SQLITE_OK;
  }
  pP1 = pBt->pPage1;
  assert( pP1!=0 );
  data = pP1->aData;
  rc = sqlite3PagerWrite(pP1->pDbPage);
  if( rc ) return rc;
  memcpy(data, zMagicHeader, sizeof(zMagicHeader));

  pBt->pageSizeFixed = 1;
#ifndef SQLITE_OMIT_AUTOVACUUM
  assert( pBt->autoVacuum==1 || pBt->autoVacuum==0 );
  assert( pBt->incrVacuum==1 || pBt->incrVacuum==0 );
  put4byte(&data[36 + 4*4], pBt->autoVacuum);
  put4byte(&data[36 + 7*4], pBt->incrVacuum);
#endif
  pBt->nPage = 1;
  data[31] = 1;
  return SQLITE_OK;
}

/*
** Attempt to start a new transaction. A write-transaction
** is started if the second argument is nonzero, otherwise a read-
** transaction.  If the second argument is 2 or more and exclusive

  /* Any read-only or read-write transaction implies a read-lock on 
  ** page 1. So if some other shared-cache client already has a write-lock 
  ** on page 1, the transaction cannot be opened. */
  rc = querySharedCacheTableLock(p, MASTER_ROOT, READ_LOCK);
  if( SQLITE_OK!=rc ) goto trans_begun;

  pBt->initiallyEmpty = pBt->nPage==0;
  do {
    /* Call lockBtree() until either pBt->pPage1 is populated or
    ** lockBtree() returns something other than SQLITE_OK. lockBtree()
    ** may return SQLITE_OK but leave pBt->pPage1 set to 0 if after
    ** reading page 1 it discovers that the page-size of the database 
    ** file is not pBt->pageSize. In this case lockBtree() will update
    ** pBt->pageSize to the page-size of the file on disk.

** process is complete.  If nFin is zero, it is assumed that
** incrVacuumStep() will be called a finite amount of times
** which may or may not empty the freelist.  A full autovacuum
** has nFin>0.  A "PRAGMA incremental_vacuum" has nFin==0.
*/
static int incrVacuumStep(BtShared *pBt, Pgno nFin, Pgno iLastPg){
  Pgno nFreeList;           /* Number of pages still on the free-list */
  int rc;

  assert( sqlite3_mutex_held(pBt->mutex) );
  assert( iLastPg>nFin );

  if( !PTRMAP_ISPAGE(pBt, iLastPg) && iLastPg!=PENDING_BYTE_PAGE(pBt) ){

    u8 eType;
    Pgno iPtrPage;

    nFreeList = get4byte(&pBt->pPage1->aData[36]);
    if( nFreeList==0 ){
      return SQLITE_DONE;
    }

  }

  if( nFin==0 ){
    iLastPg--;
    while( iLastPg==PENDING_BYTE_PAGE(pBt)||PTRMAP_ISPAGE(pBt, iLastPg) ){
      if( PTRMAP_ISPAGE(pBt, iLastPg) ){
        MemPage *pPg;
        rc = btreeGetPage(pBt, iLastPg, &pPg, 0);
        if( rc!=SQLITE_OK ){
          return rc;
        }
        rc = sqlite3PagerWrite(pPg->pDbPage);
        releasePage(pPg);
        if( rc!=SQLITE_OK ){
          return rc;
        }
      }
      iLastPg--;
    }
    sqlite3PagerTruncateImage(pBt->pPager, iLastPg);
    pBt->nPage = iLastPg;
  }
  return SQLITE_OK;
}

/*
** A write-transaction must be opened before calling this function.
** It performs a single unit of work towards an incremental vacuum.

  sqlite3BtreeEnter(p);
  assert( pBt->inTransaction==TRANS_WRITE && p->inTrans==TRANS_WRITE );
  if( !pBt->autoVacuum ){
    rc = SQLITE_DONE;
  }else{
    invalidateAllOverflowCache(pBt);
    rc = incrVacuumStep(pBt, 0, btreePagecount(pBt));
    if( rc==SQLITE_OK ){
      rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
      put4byte(&pBt->pPage1->aData[28], pBt->nPage);
    }
  }
  sqlite3BtreeLeave(p);
  return rc;
}

/*
** This routine is called prior to sqlite3PagerCommit when a transaction

    Pgno nFin;         /* Number of pages in database after autovacuuming */
    Pgno nFree;        /* Number of pages on the freelist initially */
    Pgno nPtrmap;      /* Number of PtrMap pages to be freed */
    Pgno iFree;        /* The next page to be freed */
    int nEntry;        /* Number of entries on one ptrmap page */
    Pgno nOrig;        /* Database size before freeing */

    nOrig = btreePagecount(pBt);
    if( PTRMAP_ISPAGE(pBt, nOrig) || nOrig==PENDING_BYTE_PAGE(pBt) ){
      /* It is not possible to create a database for which the final page
      ** is either a pointer-map page or the pending-byte page. If one
      ** is encountered, this indicates corruption.
      */
      return SQLITE_CORRUPT_BKPT;
    }

    }
    if( nFin>nOrig ) return SQLITE_CORRUPT_BKPT;

    for(iFree=nOrig; iFree>nFin && rc==SQLITE_OK; iFree--){
      rc = incrVacuumStep(pBt, nFin, iFree);
    }
    if( (rc==SQLITE_DONE || rc==SQLITE_OK) && nFree>0 ){

      rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
      put4byte(&pBt->pPage1->aData[32], 0);
      put4byte(&pBt->pPage1->aData[36], 0);
      put4byte(&pBt->pPage1->aData[28], nFin);
      sqlite3PagerTruncateImage(pBt->pPager, nFin);
      pBt->nPage = nFin;
    }
    if( rc!=SQLITE_OK ){
      sqlite3PagerRollback(pPager);
    }
  }

  assert( nRef==sqlite3PagerRefcount(pPager) );

      rc = rc2;
    }

    /* The rollback may have destroyed the pPage1->aData value.  So
    ** call btreeGetPage() on page 1 again to make
    ** sure pPage1->aData is set correctly. */
    if( btreeGetPage(pBt, 1, &pPage1, 0)==SQLITE_OK ){
      int nPage = get4byte(28+(u8*)pPage1->aData);
      testcase( nPage==0 );
      if( nPage==0 ) sqlite3PagerPagecount(pBt->pPager, &nPage);
      testcase( pBt->nPage!=nPage );
      pBt->nPage = nPage;
      releasePage(pPage1);
    }
    assert( countWriteCursors(pBt)==0 );
    pBt->inTransaction = TRANS_READ;
  }

  btreeEndTransaction(p);

  int rc;
  BtShared *pBt = p->pBt;
  sqlite3BtreeEnter(p);
  assert( p->inTrans==TRANS_WRITE );
  assert( pBt->readOnly==0 );
  assert( iStatement>0 );
  assert( iStatement>p->db->nSavepoint );



  assert( pBt->inTransaction==TRANS_WRITE );
  /* At the pager level, a statement transaction is a savepoint with
  ** an index greater than all savepoints created explicitly using
  ** SQL statements. It is illegal to open, release or rollback any
  ** such savepoints while the statement transaction savepoint is active.
  */
  rc = sqlite3PagerOpenSavepoint(pBt->pPager, iStatement);

  sqlite3BtreeLeave(p);
  return rc;
}

/*
** The second argument to this function, op, is always SAVEPOINT_ROLLBACK
** or SAVEPOINT_RELEASE. This function either releases or rolls back the

  if( p && p->inTrans==TRANS_WRITE ){
    BtShared *pBt = p->pBt;
    assert( op==SAVEPOINT_RELEASE || op==SAVEPOINT_ROLLBACK );
    assert( iSavepoint>=0 || (iSavepoint==-1 && op==SAVEPOINT_ROLLBACK) );
    sqlite3BtreeEnter(p);
    rc = sqlite3PagerSavepoint(pBt->pPager, op, iSavepoint);
    if( rc==SQLITE_OK ){
      if( iSavepoint<0 && pBt->initiallyEmpty ) pBt->nPage = 0;
      rc = newDatabase(pBt);
      pBt->nPage = get4byte(28 + pBt->pPage1->aData);
      if( pBt->nPage==0 ){
        sqlite3PagerPagecount(pBt->pPager, (int*)&pBt->nPage);
      }
    }
    sqlite3BtreeLeave(p);
  }
  return rc;
}

/*

  assert( p->inTrans>TRANS_NONE );
  assert( wrFlag==0 || p->inTrans==TRANS_WRITE );
  assert( pBt->pPage1 && pBt->pPage1->aData );

  if( NEVER(wrFlag && pBt->readOnly) ){
    return SQLITE_READONLY;
  }
  if( iTable==1 && btreePagecount(pBt)==0 ){
    return SQLITE_EMPTY;
  }

  /* Now that no other errors can occur, finish filling in the BtCursor
  ** variables and link the cursor into the BtShared list.  */
  pCur->pgnoRoot = (Pgno)iTable;
  pCur->iPage = -1;

    Pgno iGuess = ovfl+1;
    u8 eType;

    while( PTRMAP_ISPAGE(pBt, iGuess) || iGuess==PENDING_BYTE_PAGE(pBt) ){
      iGuess++;
    }

    if( iGuess<=btreePagecount(pBt) ){
      rc = ptrmapGet(pBt, iGuess, &eType, &pgno);
      if( rc==SQLITE_OK && eType==PTRMAP_OVERFLOW2 && pgno==ovfl ){
        next = iGuess;
        rc = SQLITE_DONE;
      }
    }
  }

  u32 k;     /* Number of leaves on the trunk of the freelist */
  MemPage *pTrunk = 0;
  MemPage *pPrevTrunk = 0;
  Pgno mxPage;     /* Total size of the database file */

  assert( sqlite3_mutex_held(pBt->mutex) );
  pPage1 = pBt->pPage1;
  mxPage = btreePagecount(pBt);
  n = get4byte(&pPage1->aData[36]);
  testcase( n==mxPage-1 );
  if( n>=mxPage ){
    return SQLITE_CORRUPT_BKPT;
  }
  if( n>0 ){
    /* There are pages on the freelist.  Reuse one of those pages. */

      }
      releasePage(pPrevTrunk);
      pPrevTrunk = 0;
    }while( searchList );
  }else{
    /* There are no pages on the freelist, so create a new page at the
    ** end of the file */
    rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
    if( rc ) return rc;
    pBt->nPage++;
    if( pBt->nPage==PENDING_BYTE_PAGE(pBt) ) pBt->nPage++;



#ifndef SQLITE_OMIT_AUTOVACUUM
    if( pBt->autoVacuum && PTRMAP_ISPAGE(pBt, pBt->nPage) ){
      /* If *pPgno refers to a pointer-map page, allocate two new pages
      ** at the end of the file instead of one. The first allocated page
      ** becomes a new pointer-map page, the second is used by the caller.
      */
      MemPage *pPg = 0;
      TRACE(("ALLOCATE: %d from end of file (pointer-map page)\n", pBt->nPage));
      assert( pBt->nPage!=PENDING_BYTE_PAGE(pBt) );
      rc = btreeGetPage(pBt, pBt->nPage, &pPg, 1);
      if( rc==SQLITE_OK ){
        rc = sqlite3PagerWrite(pPg->pDbPage);
        releasePage(pPg);
      }
      if( rc ) return rc;
      pBt->nPage++;
      if( pBt->nPage==PENDING_BYTE_PAGE(pBt) ){ pBt->nPage++; }
    }
#endif
    put4byte(28 + (u8*)pBt->pPage1->aData, pBt->nPage);
    *pPgno = pBt->nPage;

    assert( *pPgno!=PENDING_BYTE_PAGE(pBt) );
    rc = btreeGetPage(pBt, *pPgno, ppPage, 1);
    if( rc ) return rc;
    rc = sqlite3PagerWrite((*ppPage)->pDbPage);
    if( rc!=SQLITE_OK ){
      releasePage(*ppPage);
    }
    TRACE(("ALLOCATE: %d from end of file\n", *pPgno));
  }

  assert( pBt->usableSize > 4 );
  ovflPageSize = pBt->usableSize - 4;
  nOvfl = (info.nPayload - info.nLocal + ovflPageSize - 1)/ovflPageSize;
  assert( ovflPgno==0 || nOvfl>0 );
  while( nOvfl-- ){
    Pgno iNext = 0;
    MemPage *pOvfl = 0;
    if( ovflPgno<2 || ovflPgno>btreePagecount(pBt) ){
      /* 0 is not a legal page number and page 1 cannot be an 
      ** overflow page. Therefore if ovflPgno<2 or past the end of the 
      ** file the database must be corrupt. */
      return SQLITE_CORRUPT_BKPT;
    }
    if( nOvfl ){
      rc = getOverflowPage(pBt, ovflPgno, &pOvfl, &iNext);

    /* Update the pointer-map and meta-data with the new root-page number. */
    ptrmapPut(pBt, pgnoRoot, PTRMAP_ROOTPAGE, 0, &rc);
    if( rc ){
      releasePage(pRoot);
      return rc;
    }

    /* When the new root page was allocated, page 1 was made writable in
    ** order either to increase the database filesize, or to decrement the
    ** freelist count.  Hence, the sqlite3BtreeUpdateMeta() call cannot fail.
    */
    assert( sqlite3PagerIswriteable(pBt->pPage1->pDbPage) );
    rc = sqlite3BtreeUpdateMeta(p, 4, pgnoRoot);
    if( NEVER(rc) ){
      releasePage(pRoot);
      return rc;
    }

  }else{
    rc = allocateBtreePage(pBt, &pRoot, &pgnoRoot, 1, 0);
    if( rc ) return rc;

){
  MemPage *pPage;
  int rc;
  unsigned char *pCell;
  int i;

  assert( sqlite3_mutex_held(pBt->mutex) );
  if( pgno>btreePagecount(pBt) ){
    return SQLITE_CORRUPT_BKPT;
  }

  rc = getAndInitPage(pBt, pgno, &pPage);
  if( rc ) return rc;
  for(i=0; i<pPage->nCell; i++){
    pCell = findCell(pPage, i);

  char zErr[100];

  sqlite3BtreeEnter(p);
  assert( p->inTrans>TRANS_NONE && pBt->inTransaction>TRANS_NONE );
  nRef = sqlite3PagerRefcount(pBt->pPager);
  sCheck.pBt = pBt;
  sCheck.pPager = pBt->pPager;
  sCheck.nPage = btreePagecount(sCheck.pBt);
  sCheck.mxErr = mxErr;
  sCheck.nErr = 0;
  sCheck.mallocFailed = 0;
  *pnErr = 0;
  if( sCheck.nPage==0 ){
    sqlite3BtreeLeave(p);
    return 0;

      rc = sqlite3BtreeBeginTrans(p->pSrc, 0);
      bCloseTrans = 1;
    }
  
    /* Now that there is a read-lock on the source database, query the
    ** source pager for the number of pages in the database.
    */
    nSrcPage = (int)sqlite3BtreeLastPage(p->pSrc);
    assert( nSrcPage>=0 );

    for(ii=0; (nPage<0 || ii<nPage) && p->iNext<=(Pgno)nSrcPage && !rc; ii++){
      const Pgno iSrcPg = p->iNext;                 /* Source page number */
      if( iSrcPg!=PENDING_BYTE_PAGE(p->pSrc->pBt) ){
        DbPage *pSrcPg;                             /* Source page object */
        rc = sqlite3PagerGet(pSrcPager, iSrcPg, &pSrcPg);
        if( rc==SQLITE_OK ){
          rc = backupOnePage(p, iSrcPg, sqlite3PagerGetData(pSrcPg));

    nField = ((KeyInfo*)zP4)->nField;
    nByte = sizeof(*pKeyInfo) + (nField-1)*sizeof(pKeyInfo->aColl[0]) + nField;
    pKeyInfo = sqlite3Malloc( nByte );
    pOp->p4.pKeyInfo = pKeyInfo;
    if( pKeyInfo ){
      u8 *aSortOrder;
      memcpy((char*)pKeyInfo, zP4, nByte - nField);
      aSortOrder = pKeyInfo->aSortOrder;
      if( aSortOrder ){
        pKeyInfo->aSortOrder = (unsigned char*)&pKeyInfo->aColl[nField];
        memcpy(pKeyInfo->aSortOrder, aSortOrder, nField);
      }
      pOp->p4type = P4_KEYINFO;
    }else{

      sqlite3_module *pModule;
      int nArg;
      int i;
      sqlite_int64 rowid;
      Mem **apArg;
      Mem *pX;
    } ck;





    struct OP_Trace_stack_vars {
      char *zTrace;
    } cl;
  } u;
  /* End automatically generated code
  ********************************************************************/

  assert( p->magic==VDBE_MAGIC_RUN );  /* sqlite3_step() verifies this */
  sqlite3VdbeMutexArrayEnter(p);
  if( p->rc==SQLITE_NOMEM ){

  assert( u.ag.n==0 || (pOp->p2>0 && pOp->p2+u.ag.n<=p->nMem+1) );
  assert( pOp->p3<pOp->p2 || pOp->p3>=pOp->p2+u.ag.n );
  u.ag.pArg = &aMem[pOp->p2];
  for(u.ag.i=0; u.ag.i<u.ag.n; u.ag.i++, u.ag.pArg++){
    u.ag.apVal[u.ag.i] = u.ag.pArg;
    sqlite3VdbeMemStoreType(u.ag.pArg);
    REGISTER_TRACE(pOp->p2+u.ag.i, u.ag.pArg);
  }

  assert( pOp->p4type==P4_FUNCDEF || pOp->p4type==P4_VDBEFUNC );
  if( pOp->p4type==P4_FUNCDEF ){
    u.ag.ctx.pFunc = pOp->p4.pFunc;
    u.ag.ctx.pVdbeFunc = 0;
  }else{

  break;
}

/* Opcode: OpenEphemeral P1 P2 * P4 *
**
** Open a new cursor P1 to a transient table.
** The cursor is always opened read/write even if 
** the main database is read-only.  The ephemeral
** table is deleted automatically when the cursor is closed.
**
** P2 is the number of columns in the ephemeral table.
** The cursor points to a BTree table if P4==0 and to a BTree index
** if P4 is not 0.  If P4 is not NULL, it points to a KeyInfo structure
** that defines the format of keys in the index.
**
** This opcode was once called OpenTemp.  But that created
** confusion because the term "temp table", might refer either
** to a TEMP table at the SQL level, or to a table opened by
** this opcode.  Then this opcode was call OpenVirtual.  But
** that created confusion with the whole virtual-table idea.
*/
/* Opcode: OpenAutoindex P1 P2 * P4 *
**
** This opcode works the same as OP_OpenEphemeral.  It has a
** different name to distinguish its use.  Tables created using
** by this opcode will be used for automatically created transient
** indices in joins.
*/
case OP_OpenAutoindex: 
case OP_OpenEphemeral: {
#if 0  /* local variables moved into u.ax */
  VdbeCursor *pCx;
#endif /* local variables moved into u.ax */
  static const int openFlags =
      SQLITE_OPEN_READWRITE |
      SQLITE_OPEN_CREATE |

  assert( pOp->p2>0 && pOp->p2<p->nOp );
  if( u.bl.res ){
    pc = pOp->p2 - 1;
  }
  break;
}

/* Opcode: Next P1 P2 * * P5
**
** Advance cursor P1 so that it points to the next key/data pair in its
** table or index.  If there are no more key/value pairs then fall through
** to the following instruction.  But if the cursor advance was successful,
** jump immediately to P2.
**
** The P1 cursor must be for a real table, not a pseudo-table.
**
** If P5 is positive and the jump is taken, then event counter
** number P5-1 in the prepared statement is incremented.
**
** See also: Prev
*/
/* Opcode: Prev P1 P2 * * P5
**
** Back up cursor P1 so that it points to the previous key/data pair in its
** table or index.  If there is no previous key/value pairs then fall through
** to the following instruction.  But if the cursor backup was successful,
** jump immediately to P2.
**
** The P1 cursor must be for a real table, not a pseudo-table.
**
** If P5 is positive and the jump is taken, then event counter
** number P5-1 in the prepared statement is incremented.
*/
case OP_Prev:          /* jump */
case OP_Next: {        /* jump */
#if 0  /* local variables moved into u.bm */
  VdbeCursor *pC;
  BtCursor *pCrsr;
  int res;
#endif /* local variables moved into u.bm */

  CHECK_FOR_INTERRUPT;
  assert( pOp->p1>=0 && pOp->p1<p->nCursor );
  assert( pOp->p5<=ArraySize(p->aCounter) );
  u.bm.pC = p->apCsr[pOp->p1];
  if( u.bm.pC==0 ){
    break;  /* See ticket #2273 */
  }
  u.bm.pCrsr = u.bm.pC->pCursor;
  if( u.bm.pCrsr==0 ){
    u.bm.pC->nullRow = 1;

#ifndef  SQLITE_OMIT_PAGER_PRAGMAS
/* Opcode: Pagecount P1 P2 * * *
**
** Write the current number of pages in database P1 to memory cell P2.
*/
case OP_Pagecount: {            /* out2-prerelease */













  pOut->u.i = sqlite3BtreeLastPage(db->aDb[pOp->p1].pBt);

  break;
}
#endif

#ifndef SQLITE_OMIT_TRACE
/* Opcode: Trace * * * P4 *
**
** If tracing is enabled (by the sqlite3_trace()) interface, then
** the UTF-8 string contained in P4 is emitted on the trace callback.
*/
case OP_Trace: {
#if 0  /* local variables moved into u.cl */
  char *zTrace;
#endif /* local variables moved into u.cl */

  u.cl.zTrace = (pOp->p4.z ? pOp->p4.z : p->zSql);
  if( u.cl.zTrace ){
    if( db->xTrace ){
      char *z = sqlite3VdbeExpandSql(p, u.cl.zTrace);
      db->xTrace(db->pTraceArg, z);
      sqlite3DbFree(db, z);
    }
#ifdef SQLITE_DEBUG
    if( (db->flags & SQLITE_SqlTrace)!=0 ){
      sqlite3DebugPrintf("SQL-trace: %s\n", u.cl.zTrace);
    }
#endif /* SQLITE_DEBUG */
  }
  break;
}
#endif

** Sync the file.
**
** Syncing an in-memory journal is a no-op.  And, in fact, this routine
** is never called in a working implementation.  This implementation
** exists purely as a contingency, in case some malfunction in some other
** part of SQLite causes Sync to be called by mistake.
*/
static int memjrnlSync(sqlite3_file *NotUsed, int NotUsed2){
  UNUSED_PARAMETER2(NotUsed, NotUsed2);

  return SQLITE_OK;

}

/*
** Query the size of the file in bytes.
*/
static int memjrnlFileSize(sqlite3_file *pJfd, sqlite_int64 *pSize){
  MemJournal *p = (MemJournal *)pJfd;
  *pSize = (sqlite_int64) p->endpoint.iOffset;

  } else {
    return WRC_Abort;
  }
}

/*
** Allocate and return a pointer to an expression to load the column iCol
** from datasource iSrc in SrcList pSrc.
*/
SQLITE_PRIVATE Expr *sqlite3CreateColumnExpr(sqlite3 *db, SrcList *pSrc, int iSrc, int iCol){
  Expr *p = sqlite3ExprAlloc(db, TK_COLUMN, 0, 0);
  if( p ){
    struct SrcList_item *pItem = &pSrc->a[iSrc];
    p->pTab = pItem->pTab;
    p->iTable = pItem->iCursor;
    if( p->pTab->iPKey==iCol ){
      p->iColumn = -1;
    }else{
      p->iColumn = (ynVar)iCol;
      testcase( iCol==BMS );
      testcase( iCol==BMS-1 );
      pItem->colUsed |= ((Bitmask)1)<<(iCol>=BMS ? BMS-1 : iCol);
    }
    ExprSetProperty(p, EP_Resolved);
  }
  return p;
}

                    sqlite3_column_text(pStmt, 2)
                );
                int n = sqlite3_column_bytes(pStmt, 2);
                if( n>24 ){
                  n = 24;
                }
                pSample->nByte = (u8)n;
                if( n < 1){
                  pSample->u.z = 0;
                }else{
                  pSample->u.z = sqlite3DbMallocRaw(dbMem, n);
                  if( pSample->u.z ){
                    memcpy(pSample->u.z, z, n);
                  }else{
                    db->mallocFailed = 1;
                    break;
                  }
                }
              }
            }
          }
        }
      }
      rc = sqlite3_finalize(pStmt);

      if( pColumn==0 ){
        j = i;
      }else{
        for(j=0; j<pColumn->nId; j++){
          if( pColumn->a[j].idx==i ) break;
        }
      }
      if( (!useTempTable && !pList) || (pColumn && j>=pColumn->nId) ){
        sqlite3ExprCode(pParse, pTab->aCol[i].pDflt, regCols+i+1);
      }else if( useTempTable ){
        sqlite3VdbeAddOp3(v, OP_Column, srcTab, j, regCols+i+1); 
      }else{
        assert( pSelect==0 ); /* Otherwise useTempTable is true */
        sqlite3ExprCodeAndCache(pParse, pList->a[j].pExpr, regCols+i+1);
      }

    { "full_column_names",        SQLITE_FullColNames  },
    { "short_column_names",       SQLITE_ShortColNames },
    { "count_changes",            SQLITE_CountRows     },
    { "empty_result_callbacks",   SQLITE_NullCallback  },
    { "legacy_file_format",       SQLITE_LegacyFileFmt },
    { "fullfsync",                SQLITE_FullFSync     },
    { "reverse_unordered_selects", SQLITE_ReverseOrder  },
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
    { "automatic_index",          SQLITE_AutoIndex     },
#endif
#ifdef SQLITE_DEBUG
    { "sql_trace",                SQLITE_SqlTrace      },
    { "vdbe_listing",             SQLITE_VdbeListing   },
    { "vdbe_trace",               SQLITE_VdbeTrace     },
#endif
#ifndef SQLITE_OMIT_CHECK
    { "ignore_check_constraints", SQLITE_IgnoreChecks  },

    corruptSchema(pData, argv[0], 0);
  }else if( argv[2] && argv[2][0] ){
    /* Call the parser to process a CREATE TABLE, INDEX or VIEW.
    ** But because db->init.busy is set to 1, no VDBE code is generated
    ** or executed.  All the parser does is build the internal data
    ** structures that describe the table, index, or view.
    */

    int rc;
    sqlite3_stmt *pStmt;

    assert( db->init.busy );
    db->init.iDb = iDb;
    db->init.newTnum = atoi(argv[1]);
    db->init.orphanTrigger = 0;
    rc = sqlite3_prepare(db, argv[2], -1, &pStmt, 0);
    db->init.iDb = 0;

    if( SQLITE_OK!=rc ){
      if( db->init.orphanTrigger ){
        assert( iDb==1 );
      }else{
        pData->rc = rc;
        if( rc==SQLITE_NOMEM ){
          db->mallocFailed = 1;
        }else if( rc!=SQLITE_INTERRUPT && rc!=SQLITE_LOCKED ){
          corruptSchema(pData, argv[0], sqlite3_errmsg(db));
        }
      }

    }
    sqlite3_finalize(pStmt);
  }else if( argv[0]==0 ){
    corruptSchema(pData, 0, 0);
  }else{
    /* If the SQL column is blank it means this is an index that
    ** was created to be the PRIMARY KEY or to fulfill a UNIQUE
    ** constraint for a CREATE TABLE.  The index should have already
    ** been created when we processed the CREATE TABLE.  All we have

      }
    }
  }

  sqlite3VtabUnlockList(db);

  pParse->db = db;
  pParse->nQueryLoop = (double)1;
  if( nBytes>=0 && (nBytes==0 || zSql[nBytes-1]!=0) ){
    char *zSqlCopy;
    int mxLen = db->aLimit[SQLITE_LIMIT_SQL_LENGTH];
    testcase( nBytes==mxLen );
    testcase( nBytes==mxLen+1 );
    if( nBytes>mxLen ){
      sqlite3Error(db, SQLITE_TOOBIG, "statement too long");

      pParse->zTail = &zSql[pParse->zTail-zSqlCopy];
    }else{
      pParse->zTail = &zSql[nBytes];
    }
  }else{
    sqlite3RunParser(pParse, zSql, &zErrMsg);
  }
  assert( 1==(int)pParse->nQueryLoop );

  if( db->mallocFailed ){
    pParse->rc = SQLITE_NOMEM;
  }
  if( pParse->rc==SQLITE_DONE ) pParse->rc = SQLITE_OK;
  if( pParse->checkSchema ){
    schemaIsValid(pParse);

**        a separate restriction deriving from ticket #350.
**
**  (13)  The subquery and outer query do not both use LIMIT
**
**  (14)  The subquery does not use OFFSET
**
**  (15)  The outer query is not part of a compound select or the
**        subquery does not have a LIMIT clause.
**        (See ticket #2339 and ticket [02a8e81d44]).
**
**  (16)  The outer query is not an aggregate or the subquery does
**        not contain ORDER BY.  (Ticket #2942)  This used to not matter
**        until we introduced the group_concat() function.  
**
**  (17)  The sub-query is not a compound select, or it is a UNION ALL 
**        compound clause made up entirely of non-aggregate queries, and 

  /* Prior to version 3.1.2, when LIMIT and OFFSET had to be simple constants,
  ** not arbitrary expresssions, we allowed some combining of LIMIT and OFFSET
  ** because they could be computed at compile-time.  But when LIMIT and OFFSET
  ** became arbitrary expressions, we were forced to add restrictions (13)
  ** and (14). */
  if( pSub->pLimit && p->pLimit ) return 0;              /* Restriction (13) */
  if( pSub->pOffset ) return 0;                          /* Restriction (14) */
  if( p->pRightmost && pSub->pLimit ){
    return 0;                                            /* Restriction (15) */
  }
  if( pSubSrc->nSrc==0 ) return 0;                       /* Restriction (7)  */
  if( ((pSub->selFlags & SF_Distinct)!=0 || pSub->pLimit) 
         && (pSrc->nSrc>1 || isAgg) ){          /* Restrictions (4)(5)(8)(9) */
     return 0;       
  }

    sqlite3ExprCacheAffinityChange(pParse, regAgg, nArg);
    sqlite3ReleaseTempRange(pParse, regAgg, nArg);
    if( addrNext ){
      sqlite3VdbeResolveLabel(v, addrNext);
      sqlite3ExprCacheClear(pParse);
    }
  }

  /* Before populating the accumulator registers, clear the column cache.
  ** Otherwise, if any of the required column values are already present 
  ** in registers, sqlite3ExprCode() may use OP_SCopy to copy the value
  ** to pC->iMem. But by the time the value is used, the original register
  ** may have been used, invalidating the underlying buffer holding the
  ** text or blob value. See ticket [883034dcb5].
  **
  ** Another solution would be to change the OP_SCopy used to copy cached
  ** values to an OP_Copy.
  */
  sqlite3ExprCacheClear(pParse);
  for(i=0, pC=pAggInfo->aCol; i<pAggInfo->nAccumulator; i++, pC++){
    sqlite3ExprCode(pParse, pC->pExpr, pC->iMem);
  }
  pAggInfo->directMode = 0;
  sqlite3ExprCacheClear(pParse);
}

  memset(&sNC, 0, sizeof(sNC));
  sNC.pParse = pSubParse;
  pSubParse->db = db;
  pSubParse->pTriggerTab = pTab;
  pSubParse->pToplevel = pTop;
  pSubParse->zAuthContext = pTrigger->zName;
  pSubParse->eTriggerOp = pTrigger->op;
  pSubParse->nQueryLoop = pParse->nQueryLoop;

  v = sqlite3GetVdbe(pSubParse);
  if( v ){
    VdbeComment((v, "Start: %s.%s (%s %s%s%s ON %s)", 
      pTrigger->zName, onErrorText(orconf),
      (pTrigger->tr_tm==TRIGGER_BEFORE ? "BEFORE" : "AFTER"),
        (pTrigger->op==TK_UPDATE ? "UPDATE" : ""),

  pParse = sqlite3StackAllocZero(db, sizeof(*pParse));
  if( pParse==0 ){
    rc = SQLITE_NOMEM;
  }else{
    pParse->declareVtab = 1;
    pParse->db = db;
    pParse->nQueryLoop = 1;
  
    if( SQLITE_OK==sqlite3RunParser(pParse, zCreateTable, &zErr) 
     && pParse->pNewTable
     && !db->mallocFailed
     && !pParse->pNewTable->pSelect
     && (pParse->pNewTable->tabFlags & TF_Virtual)==0
    ){

#define WHERE_ROWID_EQ     0x00001000  /* rowid=EXPR or rowid IN (...) */
#define WHERE_ROWID_RANGE  0x00002000  /* rowid<EXPR and/or rowid>EXPR */
#define WHERE_COLUMN_EQ    0x00010000  /* x=EXPR or x IN (...) or x IS NULL */
#define WHERE_COLUMN_RANGE 0x00020000  /* x<EXPR and/or x>EXPR */
#define WHERE_COLUMN_IN    0x00040000  /* x IN (...) */
#define WHERE_COLUMN_NULL  0x00080000  /* x IS NULL */
#define WHERE_INDEXED      0x000f0000  /* Anything that uses an index */
#define WHERE_NOT_FULLSCAN 0x000f3000  /* Does not do a full table scan */
#define WHERE_IN_ABLE      0x000f1000  /* Able to support an IN operator */
#define WHERE_TOP_LIMIT    0x00100000  /* x<EXPR or x<=EXPR constraint */
#define WHERE_BTM_LIMIT    0x00200000  /* x>EXPR or x>=EXPR constraint */
#define WHERE_IDX_ONLY     0x00800000  /* Use index only - omit table */
#define WHERE_ORDERBY      0x01000000  /* Output will appear in correct order */
#define WHERE_REVERSE      0x02000000  /* Scan in reverse order */
#define WHERE_UNIQUE       0x04000000  /* Selects no more than one row */
#define WHERE_VIRTUALTABLE 0x08000000  /* Use virtual-table processing */
#define WHERE_MULTI_OR     0x10000000  /* OR using multiple indices */
#define WHERE_TEMP_INDEX   0x20000000  /* Uses an ephemeral index */

/*
** Initialize a preallocated WhereClause structure.
*/
static void whereClauseInit(
  WhereClause *pWC,        /* The WhereClause to be initialized */
  Parse *pParse,           /* The parsing context */

  WhereCost *pCost            /* Lowest cost query plan */
){
#ifndef SQLITE_OMIT_OR_OPTIMIZATION
  const int iCur = pSrc->iCursor;   /* The cursor of the table to be accessed */
  const Bitmask maskSrc = getMask(pWC->pMaskSet, iCur);  /* Bitmask for pSrc */
  WhereTerm * const pWCEnd = &pWC->a[pWC->nTerm];        /* End of pWC->a[] */
  WhereTerm *pTerm;                 /* A single term of the WHERE clause */

  /* No OR-clause optimization allowed if the NOT INDEXED clause is used */
  if( pSrc->notIndexed ){
    return;
  }

  /* Search the WHERE clause terms for a usable WO_OR term. */
  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
    if( pTerm->eOperator==WO_OR 
     && ((pTerm->prereqAll & ~maskSrc) & notReady)==0
     && (pTerm->u.pOrInfo->indexable & maskSrc)!=0 
    ){

        used |= sTermCost.used;
        if( rTotal>=pCost->rCost ) break;
      }

      /* If there is an ORDER BY clause, increase the scan cost to account 
      ** for the cost of the sort. */
      if( pOrderBy!=0 ){
        WHERETRACE(("... sorting increases OR cost %.9g to %.9g\n",
                    rTotal, rTotal+nRow*estLog(nRow)));
        rTotal += nRow*estLog(nRow);

      }

      /* If the cost of scanning using this OR term for optimization is
      ** less than the current cost stored in pCost, replace the contents
      ** of pCost. */
      WHERETRACE(("... multi-index OR cost=%.9g nrow=%.9g\n", rTotal, nRow));
      if( rTotal<pCost->rCost ){
        pCost->rCost = rTotal;
        pCost->nRow = nRow;
        pCost->used = used;
        pCost->plan.wsFlags = flags;
        pCost->plan.u.pTerm = pTerm;
      }
    }
  }
#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
}

#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
/*
** Return TRUE if the WHERE clause term pTerm is of a form where it
** could be used with an index to access pSrc, assuming an appropriate
** index existed.
*/
static int termCanDriveIndex(
  WhereTerm *pTerm,              /* WHERE clause term to check */
  struct SrcList_item *pSrc,     /* Table we are trying to access */
  Bitmask notReady               /* Tables in outer loops of the join */
){
  char aff;
  if( pTerm->leftCursor!=pSrc->iCursor ) return 0;
  if( pTerm->eOperator!=WO_EQ ) return 0;
  if( (pTerm->prereqRight & notReady)!=0 ) return 0;
  aff = pSrc->pTab->aCol[pTerm->u.leftColumn].affinity;
  if( !sqlite3IndexAffinityOk(pTerm->pExpr, aff) ) return 0;
  return 1;
}
#endif

#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
/*
** If the query plan for pSrc specified in pCost is a full table scan
** and indexing is allows (if there is no NOT INDEXED clause) and it
** possible to construct a transient index that would perform better
** than a full table scan even when the cost of constructing the index
** is taken into account, then alter the query plan to use the
** transient index.
*/
static void bestAutomaticIndex(
  Parse *pParse,              /* The parsing context */
  WhereClause *pWC,           /* The WHERE clause */
  struct SrcList_item *pSrc,  /* The FROM clause term to search */
  Bitmask notReady,           /* Mask of cursors that are not available */
  WhereCost *pCost            /* Lowest cost query plan */
){
  double nTableRow;           /* Rows in the input table */
  double logN;                /* log(nTableRow) */
  double costTempIdx;         /* per-query cost of the transient index */
  WhereTerm *pTerm;           /* A single term of the WHERE clause */
  WhereTerm *pWCEnd;          /* End of pWC->a[] */
  Table *pTable;              /* Table tht might be indexed */

  if( (pParse->db->flags & SQLITE_AutoIndex)==0 ){
    /* Automatic indices are disabled at run-time */
    return;
  }
  if( (pCost->plan.wsFlags & WHERE_NOT_FULLSCAN)!=0 ){
    /* We already have some kind of index in use for this query. */
    return;
  }
  if( pSrc->notIndexed ){
    /* The NOT INDEXED clause appears in the SQL. */
    return;
  }

  assert( pParse->nQueryLoop >= (double)1 );
  pTable = pSrc->pTab;
  nTableRow = pTable->pIndex ? pTable->pIndex->aiRowEst[0] : 1000000;
  logN = estLog(nTableRow);
  costTempIdx = 2*logN*(nTableRow/pParse->nQueryLoop + 1);
  if( costTempIdx>=pCost->rCost ){
    /* The cost of creating the transient table would be greater than
    ** doing the full table scan */
    return;
  }

  /* Search for any equality comparison term */
  pWCEnd = &pWC->a[pWC->nTerm];
  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
    if( termCanDriveIndex(pTerm, pSrc, notReady) ){
      WHERETRACE(("auto-index reduces cost from %.2f to %.2f\n",
                    pCost->rCost, costTempIdx));
      pCost->rCost = costTempIdx;
      pCost->nRow = logN + 1;
      pCost->plan.wsFlags = WHERE_TEMP_INDEX;
      pCost->used = pTerm->prereqRight;
      break;
    }
  }
}
#else
# define bestAutomaticIndex(A,B,C,D,E)  /* no-op */
#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */


#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
/*
** Generate code to construct the Index object for an automatic index
** and to set up the WhereLevel object pLevel so that the code generator
** makes use of the automatic index.
*/
static void constructAutomaticIndex(
  Parse *pParse,              /* The parsing context */
  WhereClause *pWC,           /* The WHERE clause */
  struct SrcList_item *pSrc,  /* The FROM clause term to get the next index */
  Bitmask notReady,           /* Mask of cursors that are not available */
  WhereLevel *pLevel          /* Write new index here */
){
  int nColumn;                /* Number of columns in the constructed index */
  WhereTerm *pTerm;           /* A single term of the WHERE clause */
  WhereTerm *pWCEnd;          /* End of pWC->a[] */
  int nByte;                  /* Byte of memory needed for pIdx */
  Index *pIdx;                /* Object describing the transient index */
  Vdbe *v;                    /* Prepared statement under construction */
  int regIsInit;              /* Register set by initialization */
  int addrInit;               /* Address of the initialization bypass jump */
  Table *pTable;              /* The table being indexed */
  KeyInfo *pKeyinfo;          /* Key information for the index */   
  int addrTop;                /* Top of the index fill loop */
  int regRecord;              /* Register holding an index record */
  int n;                      /* Column counter */
  int i;                      /* Loop counter */
  int mxBitCol;               /* Maximum column in pSrc->colUsed */
  CollSeq *pColl;             /* Collating sequence to on a column */
  Bitmask idxCols;            /* Bitmap of columns used for indexing */
  Bitmask extraCols;          /* Bitmap of additional columns */

  /* Generate code to skip over the creation and initialization of the
  ** transient index on 2nd and subsequent iterations of the loop. */
  v = pParse->pVdbe;
  assert( v!=0 );
  regIsInit = ++pParse->nMem;
  addrInit = sqlite3VdbeAddOp1(v, OP_If, regIsInit);
  sqlite3VdbeAddOp2(v, OP_Integer, 1, regIsInit);

  /* Count the number of columns that will be added to the index
  ** and used to match WHERE clause constraints */
  nColumn = 0;
  pTable = pSrc->pTab;
  pWCEnd = &pWC->a[pWC->nTerm];
  idxCols = 0;
  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
    if( termCanDriveIndex(pTerm, pSrc, notReady) ){
      int iCol = pTerm->u.leftColumn;
      Bitmask cMask = iCol>=BMS ? ((Bitmask)1)<<(BMS-1) : ((Bitmask)1)<<iCol;
      testcase( iCol==BMS );
      testcase( iCol==BMS-1 );
      if( (idxCols & cMask)==0 ){
        nColumn++;
        idxCols |= cMask;
      }
    }
  }
  assert( nColumn>0 );
  pLevel->plan.nEq = nColumn;

  /* Count the number of additional columns needed to create a
  ** covering index.  A "covering index" is an index that contains all
  ** columns that are needed by the query.  With a covering index, the
  ** original table never needs to be accessed.  Automatic indices must
  ** be a covering index because the index will not be updated if the
  ** original table changes and the index and table cannot both be used
  ** if they go out of sync.
  */
  extraCols = pSrc->colUsed & (~idxCols | (((Bitmask)1)<<(BMS-1)));
  mxBitCol = (pTable->nCol >= BMS-1) ? BMS-1 : pTable->nCol;
  testcase( pTable->nCol==BMS-1 );
  testcase( pTable->nCol==BMS-2 );
  for(i=0; i<mxBitCol; i++){
    if( extraCols & (((Bitmask)1)<<i) ) nColumn++;
  }
  if( pSrc->colUsed & (((Bitmask)1)<<(BMS-1)) ){
    nColumn += pTable->nCol - BMS + 1;
  }
  pLevel->plan.wsFlags |= WHERE_COLUMN_EQ | WHERE_IDX_ONLY | WO_EQ;

  /* Construct the Index object to describe this index */
  nByte = sizeof(Index);
  nByte += nColumn*sizeof(int);     /* Index.aiColumn */
  nByte += nColumn*sizeof(char*);   /* Index.azColl */
  nByte += nColumn;                 /* Index.aSortOrder */
  pIdx = sqlite3DbMallocZero(pParse->db, nByte);
  if( pIdx==0 ) return;
  pLevel->plan.u.pIdx = pIdx;
  pIdx->azColl = (char**)&pIdx[1];
  pIdx->aiColumn = (int*)&pIdx->azColl[nColumn];
  pIdx->aSortOrder = (u8*)&pIdx->aiColumn[nColumn];
  pIdx->zName = "auto-index";
  pIdx->nColumn = nColumn;
  pIdx->pTable = pTable;
  n = 0;
  idxCols = 0;
  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
    if( termCanDriveIndex(pTerm, pSrc, notReady) ){
      int iCol = pTerm->u.leftColumn;
      Bitmask cMask = iCol>=BMS ? ((Bitmask)1)<<(BMS-1) : ((Bitmask)1)<<iCol;
      if( (idxCols & cMask)==0 ){
        Expr *pX = pTerm->pExpr;
        idxCols |= cMask;
        pIdx->aiColumn[n] = pTerm->u.leftColumn;
        pColl = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pX->pRight);
        pIdx->azColl[n] = pColl->zName;
        n++;
      }
    }
  }
  assert( n==pLevel->plan.nEq );

  /* Add additional columns needed to make the automatic index into
  ** a covering index */
  for(i=0; i<mxBitCol; i++){
    if( extraCols & (((Bitmask)1)<<i) ){
      pIdx->aiColumn[n] = i;
      pIdx->azColl[n] = "BINARY";
      n++;
    }
  }
  if( pSrc->colUsed & (((Bitmask)1)<<(BMS-1)) ){
    for(i=BMS-1; i<pTable->nCol; i++){
      pIdx->aiColumn[n] = i;
      pIdx->azColl[n] = "BINARY";
      n++;
    }
  }
  assert( n==nColumn );

  /* Create the automatic index */
  pKeyinfo = sqlite3IndexKeyinfo(pParse, pIdx);
  assert( pLevel->iIdxCur>=0 );
  sqlite3VdbeAddOp4(v, OP_OpenAutoindex, pLevel->iIdxCur, nColumn+1, 0,
                    (char*)pKeyinfo, P4_KEYINFO_HANDOFF);
  VdbeComment((v, "for %s", pTable->zName));

  /* Fill the automatic index with content */
  addrTop = sqlite3VdbeAddOp1(v, OP_Rewind, pLevel->iTabCur);
  regRecord = sqlite3GetTempReg(pParse);
  sqlite3GenerateIndexKey(pParse, pIdx, pLevel->iTabCur, regRecord, 1);
  sqlite3VdbeAddOp2(v, OP_IdxInsert, pLevel->iIdxCur, regRecord);
  sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
  sqlite3VdbeAddOp2(v, OP_Next, pLevel->iTabCur, addrTop+1);
  sqlite3VdbeChangeP5(v, SQLITE_STMTSTATUS_AUTOINDEX);
  sqlite3VdbeJumpHere(v, addrTop);
  sqlite3ReleaseTempReg(pParse, regRecord);
  
  /* Jump here when skipping the initialization */
  sqlite3VdbeJumpHere(v, addrInit);
}
#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */

#ifndef SQLITE_OMIT_VIRTUALTABLE
/*
** Allocate and populate an sqlite3_index_info structure. It is the 
** responsibility of the caller to eventually release the structure
** by passing the pointer returned by this function to sqlite3_free().
*/
static sqlite3_index_info *allocateIndexInfo(

  Table *pTab = pSrc->pTab;
  sqlite3_index_info *pIdxInfo;
  struct sqlite3_index_constraint *pIdxCons;
  struct sqlite3_index_constraint_usage *pUsage;
  WhereTerm *pTerm;
  int i, j;
  int nOrderBy;
  double rCost;

  /* Make sure wsFlags is initialized to some sane value. Otherwise, if the 
  ** malloc in allocateIndexInfo() fails and this function returns leaving
  ** wsFlags in an uninitialized state, the caller may behave unpredictably.
  */
  memset(pCost, 0, sizeof(*pCost));
  pCost->plan.wsFlags = WHERE_VIRTUALTABLE;

  pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
  for(i=0; i<pIdxInfo->nConstraint; i++){
    if( pUsage[i].argvIndex>0 ){
      pCost->used |= pWC->a[pIdxCons[i].iTermOffset].prereqRight;
    }
  }

  /* If there is an ORDER BY clause, and the selected virtual table index
  ** does not satisfy it, increase the cost of the scan accordingly. This
  ** matches the processing for non-virtual tables in bestBtreeIndex().
  */
  rCost = pIdxInfo->estimatedCost;
  if( pOrderBy && pIdxInfo->orderByConsumed==0 ){
    rCost += estLog(rCost)*rCost;
  }

  /* The cost is not allowed to be larger than SQLITE_BIG_DBL (the
  ** inital value of lowestCost in this loop. If it is, then the
  ** (cost<lowestCost) test below will never be true.
  ** 
  ** Use "(double)2" instead of "2.0" in case OMIT_FLOATING_POINT 
  ** is defined.
  */
  if( (SQLITE_BIG_DBL/((double)2))<rCost ){
    pCost->rCost = (SQLITE_BIG_DBL/((double)2));
  }else{
    pCost->rCost = rCost;
  }
  pCost->plan.u.pVtabIdx = pIdxInfo;
  if( pIdxInfo->orderByConsumed ){
    pCost->plan.wsFlags |= WHERE_ORDERBY;
  }
  pCost->plan.nEq = 0;
  pIdxInfo->nOrderBy = nOrderBy;

    **    the sub-select is assumed to return 25 rows for the purposes of 
    **    determining nInMul.
    **
    **  bInEst:  
    **    Set to true if there was at least one "x IN (SELECT ...)" term used 
    **    in determining the value of nInMul.
    **
    **  estBound:
    **    An estimate on the amount of the table that must be searched.  A
    **    value of 100 means the entire table is searched.  Range constraints
    **    might reduce this to a value less than 100 to indicate that only
    **    a fraction of the table needs searching.  In the absence of
    **    sqlite_stat2 ANALYZE data, a single inequality reduces the search
    **    space to 1/3rd its original size.  So an x>? constraint reduces
    **    estBound to 33.  Two constraints (x>? AND x<?) reduce estBound to 11.
    **
    **  bSort:   
    **    Boolean. True if there is an ORDER BY clause that will require an 
    **    external sort (i.e. scanning the index being evaluated will not 
    **    correctly order records).
    **
    **  bLookup: 

    **
    **             SELECT a, b    FROM tbl WHERE a = 1;
    **             SELECT a, b, c FROM tbl WHERE a = 1;
    */
    int nEq;
    int bInEst = 0;
    int nInMul = 1;
    int estBound = 100;
    int nBound = 0;             /* Number of range constraints seen */
    int bSort = 0;
    int bLookup = 0;
    WhereTerm *pTerm;           /* A single term of the WHERE clause */

    /* Determine the values of nEq and nInMul */
    for(nEq=0; nEq<pProbe->nColumn; nEq++){

      int j = pProbe->aiColumn[nEq];
      pTerm = findTerm(pWC, iCur, j, notReady, eqTermMask, pIdx);
      if( pTerm==0 ) break;
      wsFlags |= (WHERE_COLUMN_EQ|WHERE_ROWID_EQ);
      if( pTerm->eOperator & WO_IN ){
        Expr *pExpr = pTerm->pExpr;
        wsFlags |= WHERE_COLUMN_IN;
        if( ExprHasProperty(pExpr, EP_xIsSelect) ){
          nInMul *= 25;
          bInEst = 1;
        }else if( pExpr->x.pList ){
          nInMul *= pExpr->x.pList->nExpr + 1;
        }
      }else if( pTerm->eOperator & WO_ISNULL ){
        wsFlags |= WHERE_COLUMN_NULL;
      }
      used |= pTerm->prereqRight;
    }

    /* Determine the value of estBound. */
    if( nEq<pProbe->nColumn ){
      int j = pProbe->aiColumn[nEq];
      if( findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE|WO_GT|WO_GE, pIdx) ){
        WhereTerm *pTop = findTerm(pWC, iCur, j, notReady, WO_LT|WO_LE, pIdx);
        WhereTerm *pBtm = findTerm(pWC, iCur, j, notReady, WO_GT|WO_GE, pIdx);
        whereRangeScanEst(pParse, pProbe, nEq, pBtm, pTop, &estBound);
        if( pTop ){
          nBound = 1;
          wsFlags |= WHERE_TOP_LIMIT;
          used |= pTop->prereqRight;
        }
        if( pBtm ){
          nBound++;
          wsFlags |= WHERE_BTM_LIMIT;
          used |= pBtm->prereqRight;
        }
        wsFlags |= (WHERE_COLUMN_RANGE|WHERE_ROWID_RANGE);
      }
    }else if( pProbe->onError!=OE_None ){
      testcase( wsFlags & WHERE_COLUMN_IN );

      }else{
        bSort = 1;
      }
    }

    /* If currently calculating the cost of using an index (not the IPK
    ** index), determine if all required column data may be obtained without 
    ** using the main table (i.e. if the index is a covering
    ** index for this query). If it is, set the WHERE_IDX_ONLY flag in
    ** wsFlags. Otherwise, set the bLookup variable to true.  */
    if( pIdx && wsFlags ){
      Bitmask m = pSrc->colUsed;
      int j;
      for(j=0; j<pIdx->nColumn; j++){
        int x = pIdx->aiColumn[j];
        if( x<BMS-1 ){
          m &= ~(((Bitmask)1)<<x);
        }
      }
      if( m==0 ){
        wsFlags |= WHERE_IDX_ONLY;
      }else{
        bLookup = 1;
      }
    }

    /*

    ** Estimate the number of rows of output.  For an IN operator,
    ** do not let the estimate exceed half the rows in the table.
    */
    nRow = (double)(aiRowEst[nEq] * nInMul);
    if( bInEst && nRow*2>aiRowEst[0] ){
      nRow = aiRowEst[0]/2;
      nInMul = (int)(nRow / aiRowEst[nEq]);
    }

    /* Assume constant cost to access a row and logarithmic cost to
    ** do a binary search.  Hence, the initial cost is the number of output
    ** rows plus log2(table-size) times the number of binary searches.
    */
    cost = nRow + nInMul*estLog(aiRowEst[0]);

    /* Adjust the number of rows and the cost downward to reflect rows
    ** that are excluded by range constraints.
    */
    nRow = (nRow * (double)estBound) / (double)100;
    cost = (cost * (double)estBound) / (double)100;

    /* Add in the estimated cost of sorting the result
    */
    if( bSort ){
      cost += cost*estLog(cost);
    }

    /* If all information can be taken directly from the index, we avoid
    ** doing table lookups.  This reduces the cost by half.  (Not really -
    ** this needs to be fixed.)
    */
    if( pIdx && bLookup==0 ){
      cost /= (double)2;
    }
    /**** Cost of using this index has now been computed ****/

    /* If there are additional constraints on this table that cannot
    ** be used with the current index, but which might lower the number
    ** of output rows, adjust the nRow value accordingly.  This only 
    ** matters if the current index is the least costly, so do not bother
    ** with this step if we already know this index will not be chosen.
    ** Also, never reduce the output row count below 2 using this step.
    **
    ** Do not reduce the output row count if pSrc is the only table that
    ** is notReady; if notReady is a power of two.  This will be the case
    ** when the main sqlite3WhereBegin() loop is scanning for a table with
    ** and "optimal" index, and on such a scan the output row count
    ** reduction is not valid because it does not update the "pCost->used"
    ** bitmap.  The notReady bitmap will also be a power of two when we
    ** are scanning for the last table in a 64-way join.  We are willing
    ** to bypass this optimization in that corner case.
    */
    if( nRow>2 && cost<=pCost->rCost && (notReady & (notReady-1))!=0 ){
      int k;                       /* Loop counter */
      int nSkipEq = nEq;           /* Number of == constraints to skip */
      int nSkipRange = nBound;     /* Number of < constraints to skip */
      Bitmask thisTab;             /* Bitmap for pSrc */

      thisTab = getMask(pWC->pMaskSet, iCur);
      for(pTerm=pWC->a, k=pWC->nTerm; nRow>2 && k; k--, pTerm++){
        if( pTerm->wtFlags & TERM_VIRTUAL ) continue;
        if( (pTerm->prereqAll & notReady)!=thisTab ) continue;
        if( pTerm->eOperator & (WO_EQ|WO_IN|WO_ISNULL) ){
          if( nSkipEq ){
            /* Ignore the first nEq equality matches since the index
            ** has already accounted for these */
            nSkipEq--;
          }else{
            /* Assume each additional equality match reduces the result
            ** set size by a factor of 10 */
            nRow /= 10;
          }
        }else if( pTerm->eOperator & (WO_LT|WO_LE|WO_GT|WO_GE) ){
          if( nSkipRange ){
            /* Ignore the first nBound range constraints since the index
            ** has already accounted for these */
            nSkipRange--;
          }else{
            /* Assume each additional range constraint reduces the result
            ** set size by a factor of 3 */
            nRow /= 3;
          }
        }else{
          /* Any other expression lowers the output row count by half */
          nRow /= 2;
        }
      }
      if( nRow<2 ) nRow = 2;
    }


    WHERETRACE((
      "%s(%s): nEq=%d nInMul=%d estBound=%d bSort=%d bLookup=%d wsFlags=0x%x\n"
      "         notReady=0x%llx nRow=%.2f cost=%.2f used=0x%llx\n",
      pSrc->pTab->zName, (pIdx ? pIdx->zName : "ipk"), 
      nEq, nInMul, estBound, bSort, bLookup, wsFlags,
      notReady, nRow, cost, used
    ));

    /* If this index is the best we have seen so far, then record this
    ** index and its cost in the pCost structure.
    */
    if( (!pIdx || wsFlags)
     && (cost<pCost->rCost || (cost<=pCost->rCost && nRow<pCost->nRow))
    ){
      pCost->rCost = cost;
      pCost->nRow = nRow;
      pCost->used = used;
      pCost->plan.wsFlags = (wsFlags&wsFlagMask);
      pCost->plan.nEq = nEq;
      pCost->plan.u.pIdx = pIdx;
    }

  assert( pCost->plan.u.pIdx==0 || (pCost->plan.wsFlags&WHERE_ROWID_EQ)==0 );
  assert( pSrc->pIndex==0 
       || pCost->plan.u.pIdx==0 
       || pCost->plan.u.pIdx==pSrc->pIndex 
  );

  WHERETRACE(("best index is: %s\n", 
    ((pCost->plan.wsFlags & WHERE_NOT_FULLSCAN)==0 ? "none" : 
         pCost->plan.u.pIdx ? pCost->plan.u.pIdx->zName : "ipk")
  ));
  
  bestOrClauseIndex(pParse, pWC, pSrc, notReady, pOrderBy, pCost);
  bestAutomaticIndex(pParse, pWC, pSrc, notReady, pCost);
  pCost->plan.wsFlags |= eqTermMask;
}

/*
** Find the query plan for accessing table pSrc->pTab. Write the
** best query plan and its cost into the WhereCost object supplied 
** as the last parameter. This function may calculate the cost of

      }
      disableTerm(pLevel, pEnd);
    }
    start = sqlite3VdbeCurrentAddr(v);
    pLevel->op = bRev ? OP_Prev : OP_Next;
    pLevel->p1 = iCur;
    pLevel->p2 = start;
    if( pStart==0 && pEnd==0 ){
      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
    }else{
      assert( pLevel->p5==0 );
    }
    if( testOp!=OP_Noop ){
      iRowidReg = iReleaseReg = sqlite3GetTempReg(pParse);
      sqlite3VdbeAddOp2(v, OP_Rowid, iCur, iRowidReg);
      sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
      sqlite3VdbeAddOp3(v, testOp, memEndValue, addrBrk, iRowidReg);
      sqlite3VdbeChangeP5(v, SQLITE_AFF_NUMERIC | SQLITE_JUMPIFNULL);
    }

#endif /* SQLITE_TEST */


/*
** Free a WhereInfo structure
*/
static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){
  if( ALWAYS(pWInfo) ){
    int i;
    for(i=0; i<pWInfo->nLevel; i++){
      sqlite3_index_info *pInfo = pWInfo->a[i].pIdxInfo;
      if( pInfo ){
        /* assert( pInfo->needToFreeIdxStr==0 || db->mallocFailed ); */
        if( pInfo->needToFreeIdxStr ){
          sqlite3_free(pInfo->idxStr);
        }
        sqlite3DbFree(db, pInfo);
      }
      if( pWInfo->a[i].plan.wsFlags & WHERE_TEMP_INDEX ){
        Index *pIdx = pWInfo->a[i].plan.u.pIdx;
        if( pIdx ){
          sqlite3DbFree(db, pIdx->zColAff);
          sqlite3DbFree(db, pIdx);
        }
      }
    }
    whereClauseClear(pWInfo->pWC);
    sqlite3DbFree(db, pWInfo);
  }
}

  int iFrom;                      /* First unused FROM clause element */
  int andFlags;              /* AND-ed combination of all pWC->a[].wtFlags */
  sqlite3 *db;               /* Database connection */

  /* The number of tables in the FROM clause is limited by the number of
  ** bits in a Bitmask 
  */
  testcase( pTabList->nSrc==BMS );
  if( pTabList->nSrc>BMS ){
    sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS);
    return 0;
  }

  /* This function normally generates a nested loop for all tables in 
  ** pTabList.  But if the WHERE_ONETABLE_ONLY flag is set, then we should

  nByteWInfo = ROUND8(sizeof(WhereInfo)+(nTabList-1)*sizeof(WhereLevel));
  pWInfo = sqlite3DbMallocZero(db, 
      nByteWInfo + 
      sizeof(WhereClause) +
      sizeof(WhereMaskSet)
  );
  if( db->mallocFailed ){
    sqlite3DbFree(db, pWInfo);
    pWInfo = 0;
    goto whereBeginError;
  }
  pWInfo->nLevel = nTabList;
  pWInfo->pParse = pParse;
  pWInfo->pTabList = pTabList;
  pWInfo->iBreak = sqlite3VdbeMakeLabel(v);
  pWInfo->pWC = pWC = (WhereClause *)&((u8 *)pWInfo)[nByteWInfo];
  pWInfo->wctrlFlags = wctrlFlags;
  pWInfo->savedNQueryLoop = pParse->nQueryLoop;
  pMaskSet = (WhereMaskSet*)&pWC[1];

  /* Split the WHERE clause into separate subexpressions where each
  ** subexpression is separated by an AND operator.
  */
  initMaskSet(pMaskSet);
  whereClauseInit(pWC, pParse, pMaskSet);

    Bitmask m;                  /* Bitmask value for j or bestJ */
    int isOptimal;              /* Iterator for optimal/non-optimal search */

    memset(&bestPlan, 0, sizeof(bestPlan));
    bestPlan.rCost = SQLITE_BIG_DBL;

    /* Loop through the remaining entries in the FROM clause to find the
    ** next nested loop. The loop tests all FROM clause entries
    ** either once or twice. 
    **
    ** The first test is always performed if there are two or more entries
    ** remaining and never performed if there is only one FROM clause entry
    ** to choose from.  The first test looks for an "optimal" scan.  In
    ** this context an optimal scan is one that uses the same strategy
    ** for the given FROM clause entry as would be selected if the entry
    ** were used as the innermost nested loop.  In other words, a table
    ** is chosen such that the cost of running that table cannot be reduced
    ** by waiting for other tables to run first.  This "optimal" test works
    ** by first assuming that the FROM clause is on the inner loop and finding
    ** its query plan, then checking to see if that query plan uses any
    ** other FROM clause terms that are notReady.  If no notReady terms are
    ** used then the "optimal" query plan works.
    **
    ** The second loop iteration is only performed if no optimal scan
    ** strategies were found by the first loop. This 2nd iteration is used to
    ** search for the lowest cost scan overall.
    **
    ** Previous versions of SQLite performed only the second iteration -
    ** the next outermost loop was always that with the lowest overall
    ** cost. However, this meant that SQLite could select the wrong plan
    ** for scripts such as the following:
    **   
    **   CREATE TABLE t1(a, b); 
    **   CREATE TABLE t2(c, d);
    **   SELECT * FROM t2, t1 WHERE t2.rowid = t1.a;
    **
    ** The best strategy is to iterate through table t1 first. However it
    ** is not possible to determine this with a simple greedy algorithm.
    ** However, since the cost of a linear scan through table t2 is the same 
    ** as the cost of a linear scan through table t1, a simple greedy 
    ** algorithm may choose to use t2 for the outer loop, which is a much
    ** costlier approach.
    */
    for(isOptimal=(iFrom<nTabList-1); isOptimal>=0; isOptimal--){
      Bitmask mask;  /* Mask of tables not yet ready */

      for(j=iFrom, pTabItem=&pTabList->a[j]; j<nTabList; j++, pTabItem++){
        int doNotReorder;    /* True if this table should not be reordered */
        WhereCost sCost;     /* Cost information from best[Virtual]Index() */
        ExprList *pOrderBy;  /* ORDER BY clause for index to optimize */
  
        doNotReorder =  (pTabItem->jointype & (JT_LEFT|JT_CROSS))!=0;
        if( j!=iFrom && doNotReorder ) break;
        m = getMask(pMaskSet, pTabItem->iCursor);
        if( (m & notReady)==0 ){
          if( j==iFrom ) iFrom++;
          continue;
        }
        mask = (isOptimal ? m : notReady);
        pOrderBy = ((i==0 && ppOrderBy )?*ppOrderBy:0);
  
        assert( pTabItem->pTab );
#ifndef SQLITE_OMIT_VIRTUALTABLE
        if( IsVirtual(pTabItem->pTab) ){
          sqlite3_index_info **pp = &pWInfo->a[j].pIdxInfo;
          bestVirtualIndex(pParse, pWC, pTabItem, mask, pOrderBy, &sCost, pp);
        }else 
#endif
        {
          bestBtreeIndex(pParse, pWC, pTabItem, mask, pOrderBy, &sCost);
        }
        assert( isOptimal || (sCost.used&notReady)==0 );

        if( (sCost.used&notReady)==0
         && (bestJ<0 || sCost.rCost<bestPlan.rCost
             || (sCost.rCost<=bestPlan.rCost && sCost.nRow<bestPlan.nRow))
        ){
          WHERETRACE(("... best so far with cost=%g and nRow=%g\n",
                      sCost.rCost, sCost.nRow));
          bestPlan = sCost;
          bestJ = j;
        }
        if( doNotReorder ) break;
      }
    }
    assert( bestJ>=0 );
    assert( notReady & getMask(pMaskSet, pTabList->a[bestJ].iCursor) );
    WHERETRACE(("*** Optimizer selects table %d for loop %d\n", bestJ,
           pLevel-pWInfo->a));
    if( (bestPlan.plan.wsFlags & WHERE_ORDERBY)!=0 ){
      *ppOrderBy = 0;
    }
    andFlags &= bestPlan.plan.wsFlags;
    pLevel->plan = bestPlan.plan;
    testcase( bestPlan.plan.wsFlags & WHERE_INDEXED );
    testcase( bestPlan.plan.wsFlags & WHERE_TEMP_INDEX );
    if( bestPlan.plan.wsFlags & (WHERE_INDEXED|WHERE_TEMP_INDEX) ){
      pLevel->iIdxCur = pParse->nTab++;
    }else{
      pLevel->iIdxCur = -1;
    }
    notReady &= ~getMask(pMaskSet, pTabList->a[bestJ].iCursor);
    pLevel->iFrom = (u8)bestJ;
    if( bestPlan.nRow>=(double)1 ) pParse->nQueryLoop *= bestPlan.nRow;

    /* Check that if the table scanned by this loop iteration had an
    ** INDEXED BY clause attached to it, that the named index is being
    ** used for the scan. If not, then query compilation has failed.
    ** Return an error.
    */
    pIdx = pTabList->a[bestJ].pIndex;

    pWInfo->a[0].plan.wsFlags &= ~WHERE_IDX_ONLY;
  }

  /* Open all tables in the pTabList and any indices selected for
  ** searching those tables.
  */
  sqlite3CodeVerifySchema(pParse, -1); /* Insert the cookie verifier Goto */
  notReady = ~(Bitmask)0;
  for(i=0, pLevel=pWInfo->a; i<nTabList; i++, pLevel++){
    Table *pTab;     /* Table to open */
    int iDb;         /* Index of database containing table/index */

#ifndef SQLITE_OMIT_EXPLAIN
    if( pParse->explain==2 ){
      char *zMsg;
      struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom];
      zMsg = sqlite3MPrintf(db, "TABLE %s", pItem->zName);
      if( pItem->zAlias ){
        zMsg = sqlite3MAppendf(db, zMsg, "%s AS %s", zMsg, pItem->zAlias);
      }
      if( (pLevel->plan.wsFlags & WHERE_TEMP_INDEX)!=0 ){
        zMsg = sqlite3MAppendf(db, zMsg, "%s WITH AUTOMATIC INDEX", zMsg);
      }else if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){
        zMsg = sqlite3MAppendf(db, zMsg, "%s WITH INDEX %s",
           zMsg, pLevel->plan.u.pIdx->zName);
      }else if( pLevel->plan.wsFlags & WHERE_MULTI_OR ){
        zMsg = sqlite3MAppendf(db, zMsg, "%s VIA MULTI-INDEX UNION", zMsg);
      }else if( pLevel->plan.wsFlags & (WHERE_ROWID_EQ|WHERE_ROWID_RANGE) ){
        zMsg = sqlite3MAppendf(db, zMsg, "%s USING PRIMARY KEY", zMsg);
      }

        zMsg = sqlite3MAppendf(db, zMsg, "%s ORDER BY", zMsg);
      }
      sqlite3VdbeAddOp4(v, OP_Explain, i, pLevel->iFrom, 0, zMsg, P4_DYNAMIC);
    }
#endif /* SQLITE_OMIT_EXPLAIN */
    pTabItem = &pTabList->a[pLevel->iFrom];
    pTab = pTabItem->pTab;
    pLevel->iTabCur = pTabItem->iCursor;
    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
    if( (pTab->tabFlags & TF_Ephemeral)!=0 || pTab->pSelect ){
      /* Do nothing */
    }else
#ifndef SQLITE_OMIT_VIRTUALTABLE
    if( (pLevel->plan.wsFlags & WHERE_VIRTUALTABLE)!=0 ){
      const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
      int iCur = pTabItem->iCursor;
      sqlite3VdbeAddOp4(v, OP_VOpen, iCur, 0, 0, pVTab, P4_VTAB);
    }else
#endif
    if( (pLevel->plan.wsFlags & WHERE_IDX_ONLY)==0
         && (wctrlFlags & WHERE_OMIT_OPEN)==0 ){
      int op = pWInfo->okOnePass ? OP_OpenWrite : OP_OpenRead;
      sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op);
      testcase( pTab->nCol==BMS-1 );
      testcase( pTab->nCol==BMS );
      if( !pWInfo->okOnePass && pTab->nCol<BMS ){
        Bitmask b = pTabItem->colUsed;
        int n = 0;
        for(; b; b=b>>1, n++){}
        sqlite3VdbeChangeP4(v, sqlite3VdbeCurrentAddr(v)-1, 
                            SQLITE_INT_TO_PTR(n), P4_INT32);
        assert( n<=pTab->nCol );
      }
    }else{
      sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
    }
#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
    if( (pLevel->plan.wsFlags & WHERE_TEMP_INDEX)!=0 ){
      constructAutomaticIndex(pParse, pWC, pTabItem, notReady, pLevel);
    }else
#endif
    if( (pLevel->plan.wsFlags & WHERE_INDEXED)!=0 ){
      Index *pIx = pLevel->plan.u.pIdx;
      KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIx);
      int iIdxCur = pLevel->iIdxCur;
      assert( pIx->pSchema==pTab->pSchema );
      assert( iIdxCur>=0 );
      sqlite3VdbeAddOp4(v, OP_OpenRead, iIdxCur, pIx->tnum, iDb,
                        (char*)pKey, P4_KEYINFO_HANDOFF);
      VdbeComment((v, "%s", pIx->zName));
    }
    sqlite3CodeVerifySchema(pParse, iDb);
    notReady &= ~getMask(pWC->pMaskSet, pTabItem->iCursor);
  }
  pWInfo->iTop = sqlite3VdbeCurrentAddr(v);
  if( db->mallocFailed ) goto whereBeginError;

  /* Generate the code to do the search.  Each iteration of the for
  ** loop below generates code for a single nested loop of the VM
  ** program.
  */
  notReady = ~(Bitmask)0;
  for(i=0; i<nTabList; i++){

  /* Record the continuation address in the WhereInfo structure.  Then
  ** clean up and return.
  */
  return pWInfo;

  /* Jump here if malloc fails */
whereBeginError:
  if( pWInfo ){
    pParse->nQueryLoop = pWInfo->savedNQueryLoop;
    whereInfoFree(db, pWInfo);
  }
  return 0;
}

/*
** Generate the end of the WHERE loop.  See comments on 
** sqlite3WhereBegin() for additional information.
*/

  /* Close all of the cursors that were opened by sqlite3WhereBegin.
  */
  assert( pWInfo->nLevel==1 || pWInfo->nLevel==pTabList->nSrc );
  for(i=0, pLevel=pWInfo->a; i<pWInfo->nLevel; i++, pLevel++){
    struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom];
    Table *pTab = pTabItem->pTab;
    assert( pTab!=0 );
    if( (pTab->tabFlags & TF_Ephemeral)==0
     && pTab->pSelect==0
     && (pWInfo->wctrlFlags & WHERE_OMIT_CLOSE)==0
    ){
      int ws = pLevel->plan.wsFlags;
      if( !pWInfo->okOnePass && (ws & WHERE_IDX_ONLY)==0 ){
        sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor);
      }
      if( (ws & WHERE_INDEXED)!=0 && (ws & WHERE_TEMP_INDEX)==0 ){
        sqlite3VdbeAddOp1(v, OP_Close, pLevel->iIdxCur);
      }
    }

    /* If this scan uses an index, make code substitutions to read data
    ** from the index in preference to the table. Sometimes, this means
    ** the table need never be read from. This is a performance boost,

        }
      }
    }
  }

  /* Final cleanup
  */
  pParse->nQueryLoop = pWInfo->savedNQueryLoop;
  whereInfoFree(db, pWInfo);
  return;
}

/************** End of where.c ***********************************************/
/************** Begin file parse.c *******************************************/
/* Driver template for the LEMON parser generator.

  db->aDb = db->aDbStatic;

  assert( sizeof(db->aLimit)==sizeof(aHardLimit) );
  memcpy(db->aLimit, aHardLimit, sizeof(db->aLimit));
  db->autoCommit = 1;
  db->nextAutovac = -1;
  db->nextPagesize = 0;
  db->flags |= SQLITE_ShortColNames | SQLITE_AutoIndex
#if SQLITE_DEFAULT_FILE_FORMAT<4
                 | SQLITE_LegacyFileFmt
#endif
#ifdef SQLITE_ENABLE_LOAD_EXTENSION
                 | SQLITE_LoadExtension
#endif
#if SQLITE_DEFAULT_RECURSIVE_TRIGGERS

** 14 bits - BA
** 21 bits - BBA
** and so on.
**
** This is similar in concept to how sqlite encodes "varints" but
** the encoding is not the same.  SQLite varints are big-endian
** are are limited to 9 bytes in length whereas FTS3 varints are
** little-endian and can be up to 10 bytes in length (in theory).
**
** Example encodings:
**
**     1:    0x01
**   127:    0x7f
**   128:    0x81 0x00
**
**
**** Document lists ****
** A doclist (document list) holds a docid-sorted list of hits for a
** given term.  Doclists hold docids and associated token positions.
** A docid is the unique integer identifier for a single document.
** A position is the index of a word within the document.  The first 
** word of the document has a position of 0.
**
** FTS3 used to optionally store character offsets using a compile-time
** option.  But that functionality is no longer supported.
**
** A doclist is stored like this:
**
** array {
**   varint docid;
**   array {                (position list for column 0)
**     varint position;     (2 more than the delta from previous position)
**   }
**   array {
**     varint POS_COLUMN;   (marks start of position list for new column)
**     varint column;       (index of new column)
**     array {
**       varint position;   (2 more than the delta from previous position)
**     }
**   }
**   varint POS_END;        (marks end of positions for this document.
** }
**
** Here, array { X } means zero or more occurrences of X, adjacent in
** memory.  A "position" is an index of a token in the token stream
** generated by the tokenizer. Note that POS_END and POS_COLUMN occur 
** in the same logical place as the position element, and act as sentinals
** ending a position list array.  POS_END is 0.  POS_COLUMN is 1.
** The positions numbers are not stored literally but rather as two more
** than the difference from the prior position, or the just the position plus
** 2 for the first position.  Example:
**
**   label:       A B C D E  F  G H   I  J K
**   value:     123 5 9 1 1 14 35 0 234 72 0
**
** The 123 value is the first docid.  For column zero in this document
** there are two matches at positions 3 and 10 (5-2 and 9-2+3).  The 1
** at D signals the start of a new column; the 1 at E indicates that the
** new column is column number 1.  There are two positions at 12 and 45
** (14-2 and 35-2+12).  The 0 at H indicate the end-of-document.  The
** 234 at I is the next docid.  It has one position 72 (72-2) and then
** terminates with the 0 at K.
**
** A "position-list" is the list of positions for multiple columns for
** a single docid.  A "column-list" is the set of positions for a single
** column.  Hence, a position-list consists of one or more column-lists,
** a document record consists of a docid followed by a position-list and
** a doclist consists of one or more document records.
**


** A bare doclist omits the position information, becoming an 
** array of varint-encoded docids.
**
**** Segment leaf nodes ****
** Segment leaf nodes store terms and doclists, ordered by term.  Leaf
** nodes are written using LeafWriter, and read using LeafReader (to
** iterate through a single leaf node's data) and LeavesReader (to
** iterate through a segment's entire leaf layer).  Leaf nodes have
** the format:

/*
** Maximum length of a varint encoded integer. The varint format is different
** from that used by SQLite, so the maximum length is 10, not 9.
*/
#define FTS3_VARINT_MAX 10

/*
** The testcase() macro is only used by the amalgamation.  If undefined,
** make it a no-op.
*/
#ifndef testcase
# define testcase(X)
#endif

/*
** Terminator values for position-lists and column-lists.
*/
#define POS_COLUMN  (1)     /* Column-list terminator */
#define POS_END     (0)     /* Position-list terminator */ 

/*
** This section provides definitions to allow the
** FTS3 extension to be compiled outside of the 
** amalgamation.
*/
#ifndef SQLITE_AMALGAMATION
/*

 sqlite_int64 i;
 int ret = sqlite3Fts3GetVarint(p, &i);
 *pi = (int) i;
 return ret;
}

/*
** Return the number of bytes required to encode v as a varint

*/
SQLITE_PRIVATE int sqlite3Fts3VarintLen(sqlite3_uint64 v){
  int i = 0;
  do{
    i++;
    v >>= 7;
  }while( v!=0 );

    }
    z[iOut] = '\0';
  }
}

/*
** Read a single varint from the doclist at *pp and advance *pp to point
** to the first byte past the end of the varint.  Add the value of the varint
** to *pVal.
*/
static void fts3GetDeltaVarint(char **pp, sqlite3_int64 *pVal){
  sqlite3_int64 iVal;
  *pp += sqlite3Fts3GetVarint(*pp, &iVal);
  *pVal += iVal;
}

/*
** Construct one or more SQL statements from the format string given
** and then evaluate those statements.  The success code is writting
** into *pRc.
**
** If *pRc is initially non-zero then this routine is a no-op.
*/
static void fts3DbExec(
  int *pRc,              /* Success code */
  sqlite3 *db,           /* Database in which to run SQL */
  const char *zFormat,   /* Format string for SQL */
  ...                    /* Arguments to the format string */
){
  va_list ap;
  char *zSql;

  return rc;
}

/*
** Create the backing store tables (%_content, %_segments and %_segdir)
** required by the FTS3 table passed as the only argument. This is done
** as part of the vtab xCreate() method.
**
** If the p->bHasDocsize boolean is true (indicating that this is an
** FTS4 table, not an FTS3 table) then also create the %_docsize and
** %_stat tables required by FTS4.
*/
static int fts3CreateTables(Fts3Table *p){
  int rc = SQLITE_OK;             /* Return code */
  int i;                          /* Iterator variable */
  char *zContentCols;             /* Columns of %_content table */
  sqlite3 *db = p->db;            /* The database connection */

/*
** This function is the implementation of both the xConnect and xCreate
** methods of the FTS3 virtual table.
**
** The argv[] array contains the following:
**
**   argv[0]   -> module name  ("fts3" or "fts4")
**   argv[1]   -> database name
**   argv[2]   -> table name
**   argv[...] -> "column name" and other module argument fields.
*/
static int fts3InitVtab(
  int isCreate,                   /* True for xCreate, false for xConnect */
  sqlite3 *db,                    /* The SQLite database connection */
  void *pAux,                     /* Hash table containing tokenizers */
  int argc,                       /* Number of elements in argv array */
  const char * const *argv,       /* xCreate/xConnect argument array */
  sqlite3_vtab **ppVTab,          /* Write the resulting vtab structure here */
  char **pzErr                    /* Write any error message here */
){
  Fts3Hash *pHash = (Fts3Hash *)pAux;
  Fts3Table *p;                   /* Pointer to allocated vtab */
  int rc;                         /* Return code */
  int i;                          /* Iterator variable */
  int nByte;                      /* Size of allocation used for *p */
  int iCol;                       /* Column index */
  int nString = 0;                /* Bytes required to hold all column names */
  int nCol = 0;                   /* Number of columns in the FTS table */
  char *zCsr;                     /* Space for holding column names */
  int nDb;                        /* Bytes required to hold database name */
  int nName;                      /* Bytes required to hold table name */

  const char *zTokenizer = 0;               /* Name of tokenizer to use */
  sqlite3_tokenizer *pTokenizer = 0;        /* Tokenizer for this table */

  nDb = (int)strlen(argv[1]) + 1;
  nName = (int)strlen(argv[2]) + 1;
  for(i=3; i<argc; i++){

  sqlite3Fts3ExprFree(pCsr->pExpr);
  sqlite3_free(pCsr->aDoclist);
  sqlite3_free(pCsr->aMatchinfo);
  sqlite3_free(pCsr);
  return SQLITE_OK;
}

/*
** Position the pCsr->pStmt statement so that it is on the row
** of the %_content table that contains the last match.  Return
** SQLITE_OK on success.  
*/
static int fts3CursorSeek(sqlite3_context *pContext, Fts3Cursor *pCsr){
  if( pCsr->isRequireSeek ){
    pCsr->isRequireSeek = 0;
    sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);
    if( SQLITE_ROW==sqlite3_step(pCsr->pStmt) ){
      return SQLITE_OK;
    }else{

      return rc;
    }
  }else{
    return SQLITE_OK;
  }
}

/*
** Advance the cursor to the next row in the %_content table that
** matches the search criteria.  For a MATCH search, this will be
** the next row that matches.  For a full-table scan, this will be
** simply the next row in the %_content table.  For a docid lookup,
** this routine simply sets the EOF flag.
**
** Return SQLITE_OK if nothing goes wrong.  SQLITE_OK is returned
** even if we reach end-of-file.  The fts3EofMethod() will be called
** subsequently to determine whether or not an EOF was hit.
*/
static int fts3NextMethod(sqlite3_vtab_cursor *pCursor){
  int rc = SQLITE_OK;             /* Return code */
  Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;

  if( pCsr->aDoclist==0 ){
    if( SQLITE_ROW!=sqlite3_step(pCsr->pStmt) ){
      pCsr->isEof = 1;

  *piPrev = iVal;
}

/*
** When this function is called, *ppPoslist is assumed to point to the 
** start of a position-list. After it returns, *ppPoslist points to the
** first byte after the position-list.
**
** A position list is list of positions (delta encoded) and columns for 
** a single document record of a doclist.  So, in other words, this
** routine advances *ppPoslist so that it points to the next docid in
** the doclist, or to the first byte past the end of the doclist.
**
** If pp is not NULL, then the contents of the position list are copied
** to *pp. *pp is set to point to the first byte past the last byte copied
** before this function returns.
*/
static void fts3PoslistCopy(char **pp, char **ppPoslist){
  char *pEnd = *ppPoslist;
  char c = 0;

  /* The end of a position list is marked by a zero encoded as an FTS3 
  ** varint. A single POS_END (0) byte. Except, if the 0 byte is preceded by
  ** a byte with the 0x80 bit set, then it is not a varint 0, but the tail
  ** of some other, multi-byte, value.
  **
  ** The following while-loop moves pEnd to point to the first byte that is not 
  ** immediately preceded by a byte with the 0x80 bit set. Then increments
  ** pEnd once more so that it points to the byte immediately following the
  ** last byte in the position-list.
  */
  while( *pEnd | c ){
    c = *pEnd++ & 0x80;
    testcase( c!=0 && (*pEnd)==0 );
  }
  pEnd++;  /* Advance past the POS_END terminator byte */

  if( pp ){
    int n = (int)(pEnd - *ppPoslist);
    char *p = *pp;
    memcpy(p, *ppPoslist, n);
    p += n;
    *pp = p;
  }
  *ppPoslist = pEnd;
}

/*
** When this function is called, *ppPoslist is assumed to point to the 
** start of a column-list. After it returns, *ppPoslist points to the
** to the terminator (POS_COLUMN or POS_END) byte of the column-list.
**
** A column-list is list of delta-encoded positions for a single column
** within a single document within a doclist.
**
** The column-list is terminated either by a POS_COLUMN varint (1) or
** a POS_END varint (0).  This routine leaves *ppPoslist pointing to
** the POS_COLUMN or POS_END that terminates the column-list.
**
** If pp is not NULL, then the contents of the column-list are copied
** to *pp. *pp is set to point to the first byte past the last byte copied
** before this function returns.  The POS_COLUMN or POS_END terminator
** is not copied into *pp.
*/
static void fts3ColumnlistCopy(char **pp, char **ppPoslist){
  char *pEnd = *ppPoslist;
  char c = 0;

  /* A column-list is terminated by either a 0x01 or 0x00 byte that is
  ** not part of a multi-byte varint.
  */
  while( 0xFE & (*pEnd | c) ){
    c = *pEnd++ & 0x80;
    testcase( c!=0 && ((*pEnd)&0xfe)==0 );
  }
  if( pp ){
    int n = (int)(pEnd - *ppPoslist);
    char *p = *pp;
    memcpy(p, *ppPoslist, n);
    p += n;
    *pp = p;
  }
  *ppPoslist = pEnd;
}

/*
** Value used to signify the end of an position-list. This is safe because
** it is not possible to have a document with 2^31 terms.
*/
#define POSITION_LIST_END 0x7fffffff

/*
** This function is used to help parse position-lists. When this function is
** called, *pp may point to the start of the next varint in the position-list
** being parsed, or it may point to 1 byte past the end of the position-list
** (in which case **pp will be a terminator bytes POS_END (0) or
** (1)).
**
** If *pp points past the end of the current position-list, set *pi to 
** POSITION_LIST_END and return. Otherwise, read the next varint from *pp,
** increment the current value of *pi by the value read, and set *pp to
** point to the next value before returning.
**
** Before calling this routine *pi must be initialized to the value of
** the previous position, or zero if we are reading the first position
** in the position-list.  Because positions are delta-encoded, the value
** of the previous position is needed in order to compute the value of
** the next position.
*/
static void fts3ReadNextPos(
  char **pp,                    /* IN/OUT: Pointer into position-list buffer */
  sqlite3_int64 *pi             /* IN/OUT: Value read from position-list */
){
  if( (**pp)&0xFE ){
    fts3GetDeltaVarint(pp, pi);
    *pi -= 2;
  }else{
    *pi = POSITION_LIST_END;
  }
}

/*
** If parameter iCol is not 0, write an POS_COLUMN (1) byte followed by
** the value of iCol encoded as a varint to *pp.   This will start a new
** column list.
**
** Set *pp to point to the byte just after the last byte written before 
** returning (do not modify it if iCol==0). Return the total number of bytes
** written (0 if iCol==0).
*/
static int fts3PutColNumber(char **pp, int iCol){
  int n = 0;                      /* Number of bytes written */
  if( iCol ){
    char *p = *pp;                /* Output pointer */
    n = 1 + sqlite3Fts3PutVarint(&p[1], iCol);
    *p = 0x01;
    *pp = &p[n];
  }
  return n;
}

/*
** Compute the union of two position lists.  The output written
** into *pp contains all positions of both *pp1 and *pp2 in sorted
** order and with any duplicates removed.  All pointers are
** updated appropriately.   The caller is responsible for insuring
** that there is enough space in *pp to hold the complete output.
*/
static void fts3PoslistMerge(
  char **pp,                      /* Output buffer */
  char **pp1,                     /* Left input list */
  char **pp2                      /* Right input list */
){
  char *p = *pp;
  char *p1 = *pp1;
  char *p2 = *pp2;

  while( *p1 || *p2 ){
    int iCol1;         /* The current column index in pp1 */
    int iCol2;         /* The current column index in pp2 */

    if( *p1==POS_COLUMN ) sqlite3Fts3GetVarint32(&p1[1], &iCol1);
    else if( *p1==POS_END ) iCol1 = POSITION_LIST_END;
    else iCol1 = 0;

    if( *p2==POS_COLUMN ) sqlite3Fts3GetVarint32(&p2[1], &iCol2);
    else if( *p2==POS_END ) iCol2 = POSITION_LIST_END;
    else iCol2 = 0;

    if( iCol1==iCol2 ){
      sqlite3_int64 i1 = 0;       /* Last position from pp1 */
      sqlite3_int64 i2 = 0;       /* Last position from pp2 */
      sqlite3_int64 iPrev = 0;
      int n = fts3PutColNumber(&p, iCol1);
      p1 += n;
      p2 += n;

      /* At this point, both p1 and p2 point to the start of column-lists
      ** for the same column (the column with index iCol1 and iCol2).
      ** A column-list is a list of non-negative delta-encoded varints, each 
      ** incremented by 2 before being stored. Each list is terminated by a
      ** POS_END (0) or POS_COLUMN (1). The following block merges the two lists
      ** and writes the results to buffer p. p is left pointing to the byte
      ** after the list written. No terminator (POS_END or POS_COLUMN) is
      ** written to the output.
      */
      fts3GetDeltaVarint(&p1, &i1);
      fts3GetDeltaVarint(&p2, &i2);
      do {
        fts3PutDeltaVarint(&p, &iPrev, (i1<i2) ? i1 : i2); 
        iPrev -= 2;
        if( i1==i2 ){
          fts3ReadNextPos(&p1, &i1);
          fts3ReadNextPos(&p2, &i2);
        }else if( i1<i2 ){
          fts3ReadNextPos(&p1, &i1);
        }else{
          fts3ReadNextPos(&p2, &i2);
        }
      }while( i1!=POSITION_LIST_END || i2!=POSITION_LIST_END );
    }else if( iCol1<iCol2 ){
      p1 += fts3PutColNumber(&p, iCol1);
      fts3ColumnlistCopy(&p, &p1);
    }else{
      p2 += fts3PutColNumber(&p, iCol2);
      fts3ColumnlistCopy(&p, &p2);
    }
  }

  *p++ = POS_END;
  *pp = p;
  *pp1 = p1 + 1;
  *pp2 = p2 + 1;
}

/*
** nToken==1 searches for adjacent positions.

  char *p = (pp ? *pp : 0);
  char *p1 = *pp1;
  char *p2 = *pp2;

  int iCol1 = 0;
  int iCol2 = 0;
  assert( *p1!=0 && *p2!=0 );
  if( *p1==POS_COLUMN ){ 
    p1++;
    p1 += sqlite3Fts3GetVarint32(p1, &iCol1);
  }
  if( *p2==POS_COLUMN ){ 
    p2++;
    p2 += sqlite3Fts3GetVarint32(p2, &iCol2);
  }

  while( 1 ){
    if( iCol1==iCol2 ){
      char *pSave = p;
      sqlite3_int64 iPrev = 0;
      sqlite3_int64 iPos1 = 0;
      sqlite3_int64 iPos2 = 0;

      if( pp && iCol1 ){
        *p++ = POS_COLUMN;
        p += sqlite3Fts3PutVarint(p, iCol1);
      }

      assert( *p1!=POS_END && *p1!=POS_COLUMN );
      assert( *p2!=POS_END && *p2!=POS_COLUMN );
      fts3GetDeltaVarint(&p1, &iPos1); iPos1 -= 2;
      fts3GetDeltaVarint(&p2, &iPos2); iPos2 -= 2;

      while( 1 ){
        if( iPos2>iPos1 && iPos2<=iPos1+nToken ){
          sqlite3_int64 iSave;
          if( !pp ){

      }
      break;
    }

    default: assert( mergetype==MERGE_POS_NEAR || mergetype==MERGE_NEAR ); {
      char *aTmp = 0;
      char **ppPos = 0;

      if( mergetype==MERGE_POS_NEAR ){
        ppPos = &p;
        aTmp = sqlite3_malloc(2*(n1+n2+1));
        if( !aTmp ){
          return SQLITE_NOMEM;
        }
      }

/*
** This function retreives the doclist for the specified term (or term
** prefix) from the database. 
**
** The returned doclist may be in one of two formats, depending on the 
** value of parameter isReqPos. If isReqPos is zero, then the doclist is
** a sorted list of delta-compressed docids (a bare doclist). If isReqPos
** is non-zero, then the returned list is in the same format as is stored 
** in the database without the found length specifier at the start of on-disk
** doclists.
*/
static int fts3TermSelect(
  Fts3Table *p,                   /* Virtual table handle */
  int iColumn,                    /* Column to query (or -ve for all columns) */
  const char *zTerm,              /* Term to query for */
  int nTerm,                      /* Size of zTerm in bytes */

    pLeft->nDoclist = nOut;
  }
  return rc;
}

/*
** Evaluate the full-text expression pExpr against fts3 table pTab. Store
** the resulting doclist in *paOut and *pnOut.  This routine mallocs for
** the space needed to store the output.  The caller is responsible for
** freeing the space when it has finished.
*/
static int evalFts3Expr(
  Fts3Table *p,                   /* Virtual table handle */
  Fts3Expr *pExpr,                /* Parsed fts3 expression */
  char **paOut,                   /* OUT: Pointer to malloc'd result buffer */
  int *pnOut,                     /* OUT: Size of buffer at *paOut */
  int isReqPos                    /* Require positions in output buffer */

**     ....X.....X....
**
** This is done as part of extracting the snippet text, not when selecting
** the snippet. Snippet selection is done based on doclists only, so there
** is no way for fts3BestSnippet() to know whether or not the document 
** actually contains terms that follow the final highlighted term. 
*/
static int fts3SnippetShift(
  Fts3Table *pTab,                /* FTS3 table snippet comes from */
  int nSnippet,                   /* Number of tokens desired for snippet */
  const char *zDoc,               /* Document text to extract snippet from */
  int nDoc,                       /* Size of buffer zDoc in bytes */
  int *piPos,                     /* IN/OUT: First token of snippet */
  u64 *pHlmask                    /* IN/OUT: Mask of tokens to highlight */
){

      if( SQLITE_ROW==sqlite3_step(pRtree->pReadRowid) ){
        sqlite3_reset(pRtree->pReadRowid);
        rc = SQLITE_CONSTRAINT;
        goto constraint;
      }
      rc = sqlite3_reset(pRtree->pReadRowid);
    }
    *pRowid = cell.iRowid;

    if( rc==SQLITE_OK ){
      rc = ChooseLeaf(pRtree, &cell, 0, &pLeaf);
    }
    if( rc==SQLITE_OK ){
      int rc2;
      pRtree->iReinsertHeight = -1;

** string contains the date and time of the check-in (UTC) and an SHA1
** hash of the entire source tree.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.6.23"
#define SQLITE_VERSION_NUMBER 3006023
#define SQLITE_SOURCE_ID      "2010-04-15 23:24:29 f96782b389b5b97b488dc5814f7082e0393f64cd"

/*
** CAPI3REF: Run-Time Library Version Numbers
** KEYWORDS: sqlite3_version, sqlite3_sourceid
**
** These interfaces provide the same information as the [SQLITE_VERSION],
** [SQLITE_VERSION_NUMBER], and [SQLITE_SOURCE_ID] C preprocessor macros

** See also: [sqlite_version()] and [sqlite_source_id()].
*/
SQLITE_API SQLITE_EXTERN const char sqlite3_version[];
SQLITE_API const char *sqlite3_libversion(void);
SQLITE_API const char *sqlite3_sourceid(void);
SQLITE_API int sqlite3_libversion_number(void);


/*
** CAPI3REF: Run-Time Library Compilation Options Diagnostics
**
** ^The sqlite3_compileoption_used() function returns 0 or 1 
** indicating whether the specified option was defined at 
** compile time.  ^The SQLITE_ prefix may be omitted from the 
** option name passed to sqlite3_compileoption_used().  

** ^Support for the diagnostic functions sqlite3_compileoption_used()
** and sqlite3_compileoption_get() may be omitted by specifing the 
** [SQLITE_OMIT_COMPILEOPTION_DIAGS] option at compile time.
**
** See also: SQL functions [sqlite_compileoption_used()] and
** [sqlite_compileoption_get()] and the [compile_options pragma].
*/
#ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
SQLITE_API int sqlite3_compileoption_used(const char *zOptName);
SQLITE_API const char *sqlite3_compileoption_get(int N);
#endif

/*
** CAPI3REF: Test To See If The Library Is Threadsafe
**
** ^The sqlite3_threadsafe() function returns zero if and only if
** SQLite was compiled mutexing code omitted due to the
** [SQLITE_THREADSAFE] compile-time option being set to 0.

** vary depending on the [SQLITE_CONFIG_SINGLETHREAD | configuration option]
** in the first argument.
**
** ^When a configuration option is set, sqlite3_config() returns [SQLITE_OK].
** ^If the option is unknown or SQLite is unable to set the option
** then this routine returns a non-zero [error code].
*/
SQLITE_API int sqlite3_config(int, ...);

/*
** CAPI3REF: Configure database connections

**
** The sqlite3_db_config() interface is used to make configuration
** changes to a [database connection].  The interface is similar to
** [sqlite3_config()] except that the changes apply to a single
** [database connection] (specified in the first argument).  The
** sqlite3_db_config() interface should only be used immediately after
** the database connection is created using [sqlite3_open()],
** [sqlite3_open16()], or [sqlite3_open_v2()].  
**
** The second argument to sqlite3_db_config(D,V,...)  is the
** configuration verb - an integer code that indicates what
** aspect of the [database connection] is being configured.
** The only choice for this value is [SQLITE_DBCONFIG_LOOKASIDE].
** New verbs are likely to be added in future releases of SQLite.
** Additional arguments depend on the verb.
**
** ^Calls to sqlite3_db_config() return SQLITE_OK if and only if
** the call is considered successful.
*/
SQLITE_API int sqlite3_db_config(sqlite3*, int op, ...);

/*
** CAPI3REF: Memory Allocation Routines

**
** An instance of this object defines the interface between SQLite
** and low-level memory allocation routines.
**
** This object is used in only one place in the SQLite interface.
** A pointer to an instance of this object is the argument to
** [sqlite3_config()] when the configuration option is

  int (*xInit)(void*);           /* Initialize the memory allocator */
  void (*xShutdown)(void*);      /* Deinitialize the memory allocator */
  void *pAppData;                /* Argument to xInit() and xShutdown() */
};

/*
** CAPI3REF: Configuration Options

**
** These constants are the available integer configuration options that
** can be passed as the first argument to the [sqlite3_config()] interface.
**
** New configuration options may be added in future releases of SQLite.
** Existing configuration options might be discontinued.  Applications
** should check the return code from [sqlite3_config()] to make sure that

** object and uses it for page cache memory allocations.</dd>
**
** <dt>SQLITE_CONFIG_GETPCACHE</dt>
** <dd> ^(This option takes a single argument which is a pointer to an
** [sqlite3_pcache_methods] object.  SQLite copies of the current
** page cache implementation into that object.)^ </dd>
**
** <dt>SQLITE_CONFIG_LOG</dt>
** <dd> ^The SQLITE_CONFIG_LOG option takes two arguments: a pointer to a
** function with a call signature of void(*)(void*,int,const char*), 
** and a pointer to void. ^If the function pointer is not NULL, it is
** invoked by [sqlite3_log()] to process each logging event.  ^If the
** function pointer is NULL, the [sqlite3_log()] interface becomes a no-op.
** ^The void pointer that is the second argument to SQLITE_CONFIG_LOG is
** passed through as the first parameter to the application-defined logger
** function whenever that function is invoked.  ^The second parameter to
** the logger function is a copy of the first parameter to the corresponding
** [sqlite3_log()] call and is intended to be a [result code] or an
** [extended result code].  ^The third parameter passed to the logger is
** log message after formatting via [sqlite3_snprintf()].
** The SQLite logging interface is not reentrant; the logger function
** supplied by the application must not invoke any SQLite interface.
** In a multi-threaded application, the application-defined logger
** function must be threadsafe. </dd>
**
** </dl>
*/
#define SQLITE_CONFIG_SINGLETHREAD  1  /* nil */
#define SQLITE_CONFIG_MULTITHREAD   2  /* nil */
#define SQLITE_CONFIG_SERIALIZED    3  /* nil */
#define SQLITE_CONFIG_MALLOC        4  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_GETMALLOC     5  /* sqlite3_mem_methods* */
#define SQLITE_CONFIG_SCRATCH       6  /* void*, int sz, int N */
#define SQLITE_CONFIG_PAGECACHE     7  /* void*, int sz, int N */
#define SQLITE_CONFIG_HEAP          8  /* void*, int nByte, int min */
#define SQLITE_CONFIG_MEMSTATUS     9  /* boolean */
#define SQLITE_CONFIG_MUTEX        10  /* sqlite3_mutex_methods* */
#define SQLITE_CONFIG_GETMUTEX     11  /* sqlite3_mutex_methods* */
/* previously SQLITE_CONFIG_CHUNKALLOC 12 which is now unused. */ 
#define SQLITE_CONFIG_LOOKASIDE    13  /* int int */
#define SQLITE_CONFIG_PCACHE       14  /* sqlite3_pcache_methods* */
#define SQLITE_CONFIG_GETPCACHE    15  /* sqlite3_pcache_methods* */
#define SQLITE_CONFIG_LOG          16  /* xFunc, void* */

/*
** CAPI3REF: Database Connection Configuration Options

**
** These constants are the available integer configuration options that
** can be passed as the second argument to the [sqlite3_db_config()] interface.
**
** New configuration options may be added in future releases of SQLite.
** Existing configuration options might be discontinued.  Applications
** should check the return code from [sqlite3_db_config()] to make sure that

#define SQLITE_DROP_VTABLE          30   /* Table Name      Module Name     */
#define SQLITE_FUNCTION             31   /* NULL            Function Name   */
#define SQLITE_SAVEPOINT            32   /* Operation       Savepoint Name  */
#define SQLITE_COPY                  0   /* No longer used */

/*
** CAPI3REF: Tracing And Profiling Functions

**
** These routines register callback functions that can be used for
** tracing and profiling the execution of SQL statements.
**
** ^The callback function registered by sqlite3_trace() is invoked at
** various times when an SQL statement is being run by [sqlite3_step()].
** ^The sqlite3_trace() callback is invoked with a UTF-8 rendering of the
** SQL statement text as the statement first begins executing.
** ^(Additional sqlite3_trace() callbacks might occur
** as each triggered subprogram is entered.  The callbacks for triggers
** contain a UTF-8 SQL comment that identifies the trigger.)^
**
** ^The callback function registered by sqlite3_profile() is invoked
** as each SQL statement finishes.  ^The profile callback contains
** the original statement text and an estimate of wall-clock time
** of how long that statement took to run.
*/
SQLITE_API void *sqlite3_trace(sqlite3*, void(*xTrace)(void*,const char*), void*);
SQLITE_API SQLITE_EXPERIMENTAL void *sqlite3_profile(sqlite3*,
   void(*xProfile)(void*,const char*,sqlite3_uint64), void*);

/*
** CAPI3REF: Query Progress Callbacks
**
** ^This routine configures a callback function - the

);
SQLITE_API int sqlite3_collation_needed16(
  sqlite3*, 
  void*,
  void(*)(void*,sqlite3*,int eTextRep,const void*)
);

#ifdef SQLITE_HAS_CODEC
/*
** Specify the key for an encrypted database.  This routine should be
** called right after sqlite3_open().
**
** The code to implement this API is not available in the public release
** of SQLite.
*/

** hook returning non-zero, just as it would be with any other rollback.
**
** ^For the purposes of this API, a transaction is said to have been
** rolled back if an explicit "ROLLBACK" statement is executed, or
** an error or constraint causes an implicit rollback to occur.
** ^The rollback callback is not invoked if a transaction is
** automatically rolled back because the database connection is closed.


**
** See also the [sqlite3_update_hook()] interface.
*/
SQLITE_API void *sqlite3_commit_hook(sqlite3*, int(*)(void*), void*);
SQLITE_API void *sqlite3_rollback_hook(sqlite3*, void(*)(void *), void*);

/*

** [sqlite3_auto_extension()] calls.)^
**
** ^This function disables automatic extensions in all threads.
*/
SQLITE_API void sqlite3_reset_auto_extension(void);

/*


** The interface to the virtual-table mechanism is currently considered
** to be experimental.  The interface might change in incompatible ways.
** If this is a problem for you, do not use the interface at this time.
**
** When the virtual-table mechanism stabilizes, we will declare the
** interface fixed, support it indefinitely, and remove this comment.
*/

/*
** Structures used by the virtual table interface
*/
typedef struct sqlite3_vtab sqlite3_vtab;
typedef struct sqlite3_index_info sqlite3_index_info;
typedef struct sqlite3_vtab_cursor sqlite3_vtab_cursor;
typedef struct sqlite3_module sqlite3_module;

/*
** CAPI3REF: Virtual Table Object
** KEYWORDS: sqlite3_module {virtual table module}

**
** This structure, sometimes called a a "virtual table module", 
** defines the implementation of a [virtual tables].  
** This structure consists mostly of methods for the module.
**
** ^A virtual table module is created by filling in a persistent
** instance of this structure and passing a pointer to that instance

                       void **ppArg);
  int (*xRename)(sqlite3_vtab *pVtab, const char *zNew);
};

/*
** CAPI3REF: Virtual Table Indexing Information
** KEYWORDS: sqlite3_index_info

**
** The sqlite3_index_info structure and its substructures is used to
** pass information into and receive the reply from the [xBestIndex]
** method of a [virtual table module].  The fields under **Inputs** are the
** inputs to xBestIndex and are read-only.  xBestIndex inserts its
** results into the **Outputs** fields.
**

#define SQLITE_INDEX_CONSTRAINT_LE    8
#define SQLITE_INDEX_CONSTRAINT_LT    16
#define SQLITE_INDEX_CONSTRAINT_GE    32
#define SQLITE_INDEX_CONSTRAINT_MATCH 64

/*
** CAPI3REF: Register A Virtual Table Implementation

**
** ^These routines are used to register a new [virtual table module] name.
** ^Module names must be registered before
** creating a new [virtual table] using the module and before using a
** preexisting [virtual table] for the module.
**
** ^The module name is registered on the [database connection] specified

** ^The sqlite3_create_module_v2() interface has a fifth parameter which
** is a pointer to a destructor for the pClientData.  ^SQLite will
** invoke the destructor function (if it is not NULL) when SQLite
** no longer needs the pClientData pointer.  ^The sqlite3_create_module()
** interface is equivalent to sqlite3_create_module_v2() with a NULL
** destructor.
*/
SQLITE_API int sqlite3_create_module(
  sqlite3 *db,               /* SQLite connection to register module with */
  const char *zName,         /* Name of the module */
  const sqlite3_module *p,   /* Methods for the module */
  void *pClientData          /* Client data for xCreate/xConnect */
);
SQLITE_API int sqlite3_create_module_v2(
  sqlite3 *db,               /* SQLite connection to register module with */
  const char *zName,         /* Name of the module */
  const sqlite3_module *p,   /* Methods for the module */
  void *pClientData,         /* Client data for xCreate/xConnect */
  void(*xDestroy)(void*)     /* Module destructor function */
);

/*
** CAPI3REF: Virtual Table Instance Object
** KEYWORDS: sqlite3_vtab

**
** Every [virtual table module] implementation uses a subclass
** of this object to describe a particular instance
** of the [virtual table].  Each subclass will
** be tailored to the specific needs of the module implementation.
** The purpose of this superclass is to define certain fields that are
** common to all module implementations.

  char *zErrMsg;                  /* Error message from sqlite3_mprintf() */
  /* Virtual table implementations will typically add additional fields */
};

/*
** CAPI3REF: Virtual Table Cursor Object
** KEYWORDS: sqlite3_vtab_cursor {virtual table cursor}

**
** Every [virtual table module] implementation uses a subclass of the
** following structure to describe cursors that point into the
** [virtual table] and are used
** to loop through the virtual table.  Cursors are created using the
** [sqlite3_module.xOpen | xOpen] method of the module and are destroyed
** by the [sqlite3_module.xClose | xClose] method.  Cursors are used

struct sqlite3_vtab_cursor {
  sqlite3_vtab *pVtab;      /* Virtual table of this cursor */
  /* Virtual table implementations will typically add additional fields */
};

/*
** CAPI3REF: Declare The Schema Of A Virtual Table

**
** ^The [xCreate] and [xConnect] methods of a
** [virtual table module] call this interface
** to declare the format (the names and datatypes of the columns) of
** the virtual tables they implement.
*/
SQLITE_API int sqlite3_declare_vtab(sqlite3*, const char *zSQL);

/*
** CAPI3REF: Overload A Function For A Virtual Table

**
** ^(Virtual tables can provide alternative implementations of functions
** using the [xFindFunction] method of the [virtual table module].  
** But global versions of those functions
** must exist in order to be overloaded.)^
**
** ^(This API makes sure a global version of a function with a particular
** name and number of parameters exists.  If no such function exists
** before this API is called, a new function is created.)^  ^The implementation
** of the new function always causes an exception to be thrown.  So
** the new function is not good for anything by itself.  Its only
** purpose is to be a placeholder function that can be overloaded
** by a [virtual table].
*/
SQLITE_API int sqlite3_overload_function(sqlite3*, const char *zFuncName, int nArg);

/*
** The interface to the virtual-table mechanism defined above (back up
** to a comment remarkably similar to this one) is currently considered
** to be experimental.  The interface might change in incompatible ways.
** If this is a problem for you, do not use the interface at this time.
**
** When the virtual-table mechanism stabilizes, we will declare the
** interface fixed, support it indefinitely, and remove this comment.


*/

/*
** CAPI3REF: A Handle To An Open BLOB
** KEYWORDS: {BLOB handle} {BLOB handles}
**
** An instance of this object represents an open BLOB on which

SQLITE_API void sqlite3_mutex_free(sqlite3_mutex*);
SQLITE_API void sqlite3_mutex_enter(sqlite3_mutex*);
SQLITE_API int sqlite3_mutex_try(sqlite3_mutex*);
SQLITE_API void sqlite3_mutex_leave(sqlite3_mutex*);

/*
** CAPI3REF: Mutex Methods Object

**
** An instance of this structure defines the low-level routines
** used to allocate and use mutexes.
**
** Usually, the default mutex implementations provided by SQLite are
** sufficient, however the user has the option of substituting a custom
** implementation for specialized deployments or systems for which SQLite

#define SQLITE_TESTCTRL_RESERVE                 14
#define SQLITE_TESTCTRL_OPTIMIZATIONS           15
#define SQLITE_TESTCTRL_ISKEYWORD               16
#define SQLITE_TESTCTRL_LAST                    16

/*
** CAPI3REF: SQLite Runtime Status

**
** ^This interface is used to retrieve runtime status information
** about the preformance of SQLite, and optionally to reset various
** highwater marks.  ^The first argument is an integer code for
** the specific parameter to measure.  ^(Recognized integer codes
** are of the form [SQLITE_STATUS_MEMORY_USED | SQLITE_STATUS_...].)^
** ^The current value of the parameter is returned into *pCurrent.

** interfaces.  However the values returned in *pCurrent and
** *pHighwater reflect the status of SQLite at different points in time
** and it is possible that another thread might change the parameter
** in between the times when *pCurrent and *pHighwater are written.
**
** See also: [sqlite3_db_status()]
*/
SQLITE_API int sqlite3_status(int op, int *pCurrent, int *pHighwater, int resetFlag);


/*
** CAPI3REF: Status Parameters

**
** These integer constants designate various run-time status parameters
** that can be returned by [sqlite3_status()].
**
** <dl>
** ^(<dt>SQLITE_STATUS_MEMORY_USED</dt>
** <dd>This parameter is the current amount of memory checked out