Fossil

    }
  }
  if( bSep ){
    utf8_printf(p->out, "%s", p->colSeparator);
  }
}


/*
** This routine runs when the user presses Ctrl-C
*/
static void interrupt_handler(int NotUsed){
  UNUSED_PARAMETER(NotUsed);
  seenInterrupt++;
  if( seenInterrupt>2 ) exit(1);
  if( globalDb ) sqlite3_interrupt(globalDb);
}

#if (defined(_WIN32) || defined(WIN32)) && !defined(_WIN32_WCE)
/*
** This routine runs for console events (e.g. Ctrl-C) on Win32
*/
static BOOL WINAPI ConsoleCtrlHandler(
  DWORD dwCtrlType /* One of the CTRL_*_EVENT constants */
){
  if( dwCtrlType==CTRL_C_EVENT ){
    interrupt_handler(0);
    return TRUE;
  }
  return FALSE;
}
#endif

#ifndef SQLITE_OMIT_AUTHORIZATION
/*
** When the ".auth ON" is set, the following authorizer callback is
** invoked.  It always returns SQLITE_OK.
*/

  Argv0 = argv[0];

  /* Make sure we have a valid signal handler early, before anything
  ** else is done.
  */
#ifdef SIGINT
  signal(SIGINT, interrupt_handler);
#elif (defined(_WIN32) || defined(WIN32)) && !defined(_WIN32_WCE)
  SetConsoleCtrlHandler(ConsoleCtrlHandler, TRUE);
#endif

#ifdef SQLITE_SHELL_DBNAME_PROC
  {
    /* If the SQLITE_SHELL_DBNAME_PROC macro is defined, then it is the name
    ** of a C-function that will provide the name of the database file.  Use
    ** this compile-time option to embed this shell program in larger

/******************************************************************************
** This file is an amalgamation of many separate C source files from SQLite
** version 3.22.0.  By combining all the individual C code files into this
** single large file, the entire code can be compiled as a single translation
** unit.  This allows many compilers to do optimizations that would not be
** possible if the files were compiled separately.  Performance improvements
** of 5% or 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

** been edited in any way since it was last checked in, then the last
** four hexadecimal digits of the hash may be modified.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.22.0"
#define SQLITE_VERSION_NUMBER 3022000
#define SQLITE_SOURCE_ID      "2017-11-14 19:34:22 00ec95fcd02bb415dabd7f25fee24856d45d6916c18b2728e97e9bb9b8322ba3"

/*
** 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

#define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
#define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
#define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
#define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
#define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
#define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
#define SQLITE_CANTOPEN_CONVPATH       (SQLITE_CANTOPEN | (4<<8))
#define SQLITE_CANTOPEN_DIRTYWAL       (SQLITE_CANTOPEN | (5<<8))
#define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
#define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
#define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))
#define SQLITE_READONLY_ROLLBACK       (SQLITE_READONLY | (3<<8))
#define SQLITE_READONLY_DBMOVED        (SQLITE_READONLY | (4<<8))
#define SQLITE_READONLY_CANTINIT       (SQLITE_READONLY | (5<<8))
#define SQLITE_ABORT_ROLLBACK          (SQLITE_ABORT | (2<<8))
#define SQLITE_CONSTRAINT_CHECK        (SQLITE_CONSTRAINT | (1<<8))
#define SQLITE_CONSTRAINT_COMMITHOOK   (SQLITE_CONSTRAINT | (2<<8))
#define SQLITE_CONSTRAINT_FOREIGNKEY   (SQLITE_CONSTRAINT | (3<<8))
#define SQLITE_CONSTRAINT_FUNCTION     (SQLITE_CONSTRAINT | (4<<8))
#define SQLITE_CONSTRAINT_NOTNULL      (SQLITE_CONSTRAINT | (5<<8))
#define SQLITE_CONSTRAINT_PRIMARYKEY   (SQLITE_CONSTRAINT | (6<<8))

** CAPI3REF: OS Interface Object
**
** An instance of the sqlite3_vfs object defines the interface between
** the SQLite core and the underlying operating system.  The "vfs"
** in the name of the object stands for "virtual file system".  See
** the [VFS | VFS documentation] for further information.
**
** The VFS interface is sometimes extended by adding new methods onto
** the end.  Each time such an extension occurs, the iVersion field
** is incremented.  The iVersion value started out as 1 in
** SQLite [version 3.5.0] on [dateof:3.5.0], then increased to 2
** with SQLite [version 3.7.0] on [dateof:3.7.0], and then increased
** to 3 with SQLite [version 3.7.6] on [dateof:3.7.6].  Additional fields
** may be appended to the sqlite3_vfs object and the iVersion value
** may increase again in future versions of SQLite.
** Note that the structure
** of the sqlite3_vfs object changes in the transition from
** SQLite [version 3.5.9] to [version 3.6.0] on [dateof:3.6.0]
** and yet the iVersion field was not modified.

**
** The szOsFile field is the size of the subclassed [sqlite3_file]
** structure used by this VFS.  mxPathname is the maximum length of
** a pathname in this VFS.
**
** Registered sqlite3_vfs objects are kept on a linked list formed by
** the pNext pointer.  The [sqlite3_vfs_register()]

};

/*
** The following are the meanings of bits in the Expr.flags field.
*/
#define EP_FromJoin  0x000001 /* Originates in ON/USING clause of outer join */
#define EP_Agg       0x000002 /* Contains one or more aggregate functions */
#define EP_HasFunc   0x000004 /* Contains one or more functions of any kind */
                  /* 0x000008 // available for use */
#define EP_Distinct  0x000010 /* Aggregate function with DISTINCT keyword */
#define EP_VarSelect 0x000020 /* pSelect is correlated, not constant */
#define EP_DblQuoted 0x000040 /* token.z was originally in "..." */
#define EP_InfixFunc 0x000080 /* True for an infix function: LIKE, GLOB, etc */
#define EP_Collate   0x000100 /* Tree contains a TK_COLLATE operator */
#define EP_Generic   0x000200 /* Ignore COLLATE or affinity on this tree */

#define EP_ConstFunc 0x080000 /* A SQLITE_FUNC_CONSTANT or _SLOCHNG function */
#define EP_CanBeNull 0x100000 /* Can be null despite NOT NULL constraint */
#define EP_Subquery  0x200000 /* Tree contains a TK_SELECT operator */
#define EP_Alias     0x400000 /* Is an alias for a result set column */
#define EP_Leaf      0x800000 /* Expr.pLeft, .pRight, .u.pSelect all NULL */

/*
** The EP_Propagate mask is a set of properties that automatically propagate
** upwards into parent nodes.
*/
#define EP_Propagate (EP_Collate|EP_Subquery|EP_HasFunc)

/*
** These macros can be used to test, set, or clear bits in the
** Expr.flags field.
*/
#define ExprHasProperty(E,P)     (((E)->flags&(P))!=0)
#define ExprHasAllProperty(E,P)  (((E)->flags&(P))==(P))

#define NC_PartIdx   0x0002  /* True if resolving a partial index WHERE */
#define NC_IsCheck   0x0004  /* True if resolving names in a CHECK constraint */
#define NC_InAggFunc 0x0008  /* True if analyzing arguments to an agg func */
#define NC_HasAgg    0x0010  /* One or more aggregate functions seen */
#define NC_IdxExpr   0x0020  /* True if resolving columns of CREATE INDEX */
#define NC_VarSelect 0x0040  /* A correlated subquery has been seen */
#define NC_MinMaxAgg 0x1000  /* min/max aggregates seen.  See note above */
#define NC_Complex   0x2000  /* True if a function or subquery seen */

/*
** An instance of the following structure contains all information
** needed to generate code for a single SELECT statement.
**
** nLimit is set to -1 if there is no LIMIT clause.  nOffset is set to 0.
** If there is a LIMIT clause, the parser sets nLimit to the value of the

#define SF_NestedFrom     0x00800  /* Part of a parenthesized FROM clause */
#define SF_MinMaxAgg      0x01000  /* Aggregate containing min() or max() */
#define SF_Recursive      0x02000  /* The recursive part of a recursive CTE */
#define SF_FixedLimit     0x04000  /* nSelectRow set by a constant LIMIT */
#define SF_MaybeConvert   0x08000  /* Need convertCompoundSelectToSubquery() */
#define SF_Converted      0x10000  /* By convertCompoundSelectToSubquery() */
#define SF_IncludeHidden  0x20000  /* Include hidden columns in output */
#define SF_ComplexResult  0x40000  /* Result set contains subquery or function */


/*
** The results of a SELECT can be distributed in several ways, as defined
** by one of the following macros.  The "SRT" prefix means "SELECT Result
** Type".
**

SQLITE_PRIVATE void sqlite3SelectDelete(sqlite3*, Select*);
SQLITE_PRIVATE Table *sqlite3SrcListLookup(Parse*, SrcList*);
SQLITE_PRIVATE int sqlite3IsReadOnly(Parse*, Table*, int);
SQLITE_PRIVATE void sqlite3OpenTable(Parse*, int iCur, int iDb, Table*, int);
#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)
SQLITE_PRIVATE Expr *sqlite3LimitWhere(Parse*,SrcList*,Expr*,ExprList*,Expr*,Expr*,char*);
#endif
SQLITE_PRIVATE void sqlite3DeleteFrom(Parse*, SrcList*, Expr*, ExprList*, Expr*, Expr*);
SQLITE_PRIVATE void sqlite3Update(Parse*, SrcList*, ExprList*,Expr*,int,ExprList*,Expr*,Expr*);
SQLITE_PRIVATE WhereInfo *sqlite3WhereBegin(Parse*,SrcList*,Expr*,ExprList*,ExprList*,u16,int);
SQLITE_PRIVATE void sqlite3WhereEnd(WhereInfo*);
SQLITE_PRIVATE LogEst sqlite3WhereOutputRowCount(WhereInfo*);
SQLITE_PRIVATE int sqlite3WhereIsDistinct(WhereInfo*);
SQLITE_PRIVATE int sqlite3WhereIsOrdered(WhereInfo*);
SQLITE_PRIVATE int sqlite3WhereOrderedInnerLoop(WhereInfo*);
SQLITE_PRIVATE int sqlite3WhereIsSorted(WhereInfo*);

SQLITE_PRIVATE void sqlite3RegisterDateTimeFunctions(void);
SQLITE_PRIVATE void sqlite3RegisterPerConnectionBuiltinFunctions(sqlite3*);
SQLITE_PRIVATE int sqlite3SafetyCheckOk(sqlite3*);
SQLITE_PRIVATE int sqlite3SafetyCheckSickOrOk(sqlite3*);
SQLITE_PRIVATE void sqlite3ChangeCookie(Parse*, int);

#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
SQLITE_PRIVATE void sqlite3MaterializeView(Parse*, Table*, Expr*, ExprList*,Expr*,Expr*,int);
#endif

#ifndef SQLITE_OMIT_TRIGGER
SQLITE_PRIVATE   void sqlite3BeginTrigger(Parse*, Token*,Token*,int,int,IdList*,SrcList*,
                           Expr*,int, int);
SQLITE_PRIVATE   void sqlite3FinishTrigger(Parse*, TriggerStep*, Token*);
SQLITE_PRIVATE   void sqlite3DropTrigger(Parse*, SrcList*, int);

  StrAccum acc;
  char zBuf[500];
  sqlite3StrAccumInit(&acc, 0, zBuf, sizeof(zBuf), 0);
  va_start(ap,zFormat);
  sqlite3VXPrintf(&acc, zFormat, ap);
  va_end(ap);
  sqlite3StrAccumFinish(&acc);
#ifdef SQLITE_OS_TRACE_PROC
  {
    extern void SQLITE_OS_TRACE_PROC(const char *zBuf, int nBuf);
    SQLITE_OS_TRACE_PROC(zBuf, sizeof(zBuf));
  }
#else
  fprintf(stdout,"%s", zBuf);
  fflush(stdout);
#endif
}
#endif


/*
** variable-argument wrapper around sqlite3VXPrintf().  The bFlags argument
** can contain the bit SQLITE_PRINTF_INTERNAL enable internal formats.

  }else if( *z=='+' ){
    z+=incr;
  }

  /* copy max significant digits to significand */
  while( z<zEnd && sqlite3Isdigit(*z) && s<((LARGEST_INT64-9)/10) ){
    s = s*10 + (*z - '0');
    z+=incr; nDigits++;
  }

  /* skip non-significant significand digits
  ** (increase exponent by d to shift decimal left) */
  while( z<zEnd && sqlite3Isdigit(*z) ){ z+=incr; nDigits++; d++; }
  if( z>=zEnd ) goto do_atof_calc;

  /* if decimal point is present */
  if( *z=='.' ){
    z+=incr;
    /* copy digits from after decimal to significand
    ** (decrease exponent by d to shift decimal right) */
    while( z<zEnd && sqlite3Isdigit(*z) ){
      if( s<((LARGEST_INT64-9)/10) ){
        s = s*10 + (*z - '0');
        d--;
      }
      z+=incr; nDigits++;
    }
  }
  if( z>=zEnd ) goto do_atof_calc;

  /* if exponent is present */
  if( *z=='e' || *z=='E' ){
    z+=incr;

#if defined(HAVE_LSTAT)
  { "lstat",         (sqlite3_syscall_ptr)lstat,          0 },
#else
  { "lstat",         (sqlite3_syscall_ptr)0,              0 },
#endif
#define osLstat      ((int(*)(const char*,struct stat*))aSyscall[27].pCurrent)

#if defined(__linux__) && defined(SQLITE_ENABLE_BATCH_ATOMIC_WRITE)
  { "ioctl",         (sqlite3_syscall_ptr)ioctl,          0 },
#else
  { "ioctl",         (sqlite3_syscall_ptr)0,              0 },
#endif
#define osIoctl ((int(*)(int,int,...))aSyscall[28].pCurrent)

}; /* End of the overrideable system calls */


/*
** On some systems, calls to fchown() will trigger a message in a security

  unixInodeInfo *pInode;     /* unixInodeInfo that owns this SHM node */
  sqlite3_mutex *mutex;      /* Mutex to access this object */
  char *zFilename;           /* Name of the mmapped file */
  int h;                     /* Open file descriptor */
  int szRegion;              /* Size of shared-memory regions */
  u16 nRegion;               /* Size of array apRegion */
  u8 isReadonly;             /* True if read-only */
  u8 isUnlocked;             /* True if no DMS lock held */
  char **apRegion;           /* Array of mapped shared-memory regions */
  int nRef;                  /* Number of unixShm objects pointing to this */
  unixShm *pFirst;           /* All unixShm objects pointing to this */
#ifdef SQLITE_DEBUG
  u8 exclMask;               /* Mask of exclusive locks held */
  u8 sharedMask;             /* Mask of shared locks held */
  u8 nextShmId;              /* Next available unixShm.id value */

      robust_close(pFd, p->h, __LINE__);
      p->h = -1;
    }
    p->pInode->pShmNode = 0;
    sqlite3_free(p);
  }
}

/*
** The DMS lock has not yet been taken on shm file pShmNode. Attempt to
** take it now. Return SQLITE_OK if successful, or an SQLite error
** code otherwise.
**
** If the DMS cannot be locked because this is a readonly_shm=1 
** connection and no other process already holds a lock, return
** SQLITE_READONLY_CANTINIT and set pShmNode->isUnlocked=1.
*/
static int unixLockSharedMemory(unixFile *pDbFd, unixShmNode *pShmNode){
  struct flock lock;
  int rc = SQLITE_OK;

  /* Use F_GETLK to determine the locks other processes are holding
  ** on the DMS byte. If it indicates that another process is holding
  ** a SHARED lock, then this process may also take a SHARED lock
  ** and proceed with opening the *-shm file. 
  **
  ** Or, if no other process is holding any lock, then this process
  ** is the first to open it. In this case take an EXCLUSIVE lock on the
  ** DMS byte and truncate the *-shm file to zero bytes in size. Then
  ** downgrade to a SHARED lock on the DMS byte.
  **
  ** If another process is holding an EXCLUSIVE lock on the DMS byte,
  ** return SQLITE_BUSY to the caller (it will try again). An earlier
  ** version of this code attempted the SHARED lock at this point. But
  ** this introduced a subtle race condition: if the process holding
  ** EXCLUSIVE failed just before truncating the *-shm file, then this
  ** process might open and use the *-shm file without truncating it.
  ** And if the *-shm file has been corrupted by a power failure or
  ** system crash, the database itself may also become corrupt.  */
  lock.l_whence = SEEK_SET;
  lock.l_start = UNIX_SHM_DMS;
  lock.l_len = 1;
  lock.l_type = F_WRLCK;
  if( osFcntl(pShmNode->h, F_GETLK, &lock)!=0 ) {
    rc = SQLITE_IOERR_LOCK;
  }else if( lock.l_type==F_UNLCK ){
    if( pShmNode->isReadonly ){
      pShmNode->isUnlocked = 1;
      rc = SQLITE_READONLY_CANTINIT;
    }else{
      rc = unixShmSystemLock(pDbFd, F_WRLCK, UNIX_SHM_DMS, 1);
      if( rc==SQLITE_OK && robust_ftruncate(pShmNode->h, 0) ){
        rc = unixLogError(SQLITE_IOERR_SHMOPEN,"ftruncate",pShmNode->zFilename);
      }
    }
  }else if( lock.l_type==F_WRLCK ){
    rc = SQLITE_BUSY;
  }

  if( rc==SQLITE_OK ){
    assert( lock.l_type==F_UNLCK || lock.l_type==F_RDLCK );
    rc = unixShmSystemLock(pDbFd, F_RDLCK, UNIX_SHM_DMS, 1);
  }
  return rc;
}

/*
** Open a shared-memory area associated with open database file pDbFd.  
** This particular implementation uses mmapped files.
**
** The file used to implement shared-memory is in the same directory
** as the open database file and has the same name as the open database

** that no other processes are able to read or write the database.  In
** that case, we do not really need shared memory.  No shared memory
** file is created.  The shared memory will be simulated with heap memory.
*/
static int unixOpenSharedMemory(unixFile *pDbFd){
  struct unixShm *p = 0;          /* The connection to be opened */
  struct unixShmNode *pShmNode;   /* The underlying mmapped file */
  int rc = SQLITE_OK;             /* Result code */
  unixInodeInfo *pInode;          /* The inode of fd */
  char *zShm;             /* Name of the file used for SHM */
  int nShmFilename;               /* Size of the SHM filename in bytes */

  /* Allocate space for the new unixShm object. */
  p = sqlite3_malloc64( sizeof(*p) );
  if( p==0 ) return SQLITE_NOMEM_BKPT;
  memset(p, 0, sizeof(*p));
  assert( pDbFd->pShm==0 );

#endif
    pShmNode = sqlite3_malloc64( sizeof(*pShmNode) + nShmFilename );
    if( pShmNode==0 ){
      rc = SQLITE_NOMEM_BKPT;
      goto shm_open_err;
    }
    memset(pShmNode, 0, sizeof(*pShmNode)+nShmFilename);
    zShm = pShmNode->zFilename = (char*)&pShmNode[1];
#ifdef SQLITE_SHM_DIRECTORY
    sqlite3_snprintf(nShmFilename, zShm, 
                     SQLITE_SHM_DIRECTORY "/sqlite-shm-%x-%x",
                     (u32)sStat.st_ino, (u32)sStat.st_dev);
#else
    sqlite3_snprintf(nShmFilename, zShm, "%s-shm", zBasePath);
    sqlite3FileSuffix3(pDbFd->zPath, zShm);
#endif
    pShmNode->h = -1;
    pDbFd->pInode->pShmNode = pShmNode;
    pShmNode->pInode = pDbFd->pInode;
    if( sqlite3GlobalConfig.bCoreMutex ){
      pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
      if( pShmNode->mutex==0 ){
        rc = SQLITE_NOMEM_BKPT;
        goto shm_open_err;
      }
    }

    if( pInode->bProcessLock==0 ){

      if( 0==sqlite3_uri_boolean(pDbFd->zPath, "readonly_shm", 0) ){

        pShmNode->h = robust_open(zShm, O_RDWR|O_CREAT, (sStat.st_mode&0777));
      }
      if( pShmNode->h<0 ){
        pShmNode->h = robust_open(zShm, O_RDONLY, (sStat.st_mode&0777));
        if( pShmNode->h<0 ){
          rc = unixLogError(SQLITE_CANTOPEN_BKPT, "open", zShm);
          goto shm_open_err;
        }
        pShmNode->isReadonly = 1;
      }

      /* If this process is running as root, make sure that the SHM file
      ** is owned by the same user that owns the original database.  Otherwise,
      ** the original owner will not be able to connect.
      */
      robustFchown(pShmNode->h, sStat.st_uid, sStat.st_gid);







      rc = unixLockSharedMemory(pDbFd, pShmNode);





      if( rc!=SQLITE_OK && rc!=SQLITE_READONLY_CANTINIT ) goto shm_open_err;
    }
  }

  /* Make the new connection a child of the unixShmNode */
  p->pShmNode = pShmNode;
#ifdef SQLITE_DEBUG
  p->id = pShmNode->nextShmId++;

  ** at pShmNode->pFirst. This must be done while holding the pShmNode->mutex 
  ** mutex.
  */
  sqlite3_mutex_enter(pShmNode->mutex);
  p->pNext = pShmNode->pFirst;
  pShmNode->pFirst = p;
  sqlite3_mutex_leave(pShmNode->mutex);
  return rc;

  /* Jump here on any error */
shm_open_err:
  unixShmPurge(pDbFd);       /* This call frees pShmNode if required */
  sqlite3_free(p);
  unixLeaveMutex();
  return rc;

    rc = unixOpenSharedMemory(pDbFd);
    if( rc!=SQLITE_OK ) return rc;
  }

  p = pDbFd->pShm;
  pShmNode = p->pShmNode;
  sqlite3_mutex_enter(pShmNode->mutex);
  if( pShmNode->isUnlocked ){
    rc = unixLockSharedMemory(pDbFd, pShmNode);
    if( rc!=SQLITE_OK ) goto shmpage_out;
    pShmNode->isUnlocked = 0;
  }
  assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 );
  assert( pShmNode->pInode==pDbFd->pInode );
  assert( pShmNode->h>=0 || pDbFd->pInode->bProcessLock==1 );
  assert( pShmNode->h<0 || pDbFd->pInode->bProcessLock==0 );

  /* Minimum number of regions required to be mapped. */
  nReqRegion = ((iRegion+nShmPerMap) / nShmPerMap) * nShmPerMap;

struct winShmNode {
  sqlite3_mutex *mutex;      /* Mutex to access this object */
  char *zFilename;           /* Name of the file */
  winFile hFile;             /* File handle from winOpen */

  int szRegion;              /* Size of shared-memory regions */
  int nRegion;               /* Size of array apRegion */
  u8 isReadonly;             /* True if read-only */
  u8 isUnlocked;             /* True if no DMS lock held */

  struct ShmRegion {
    HANDLE hMap;             /* File handle from CreateFileMapping */
    void *pMap;
  } *aRegion;
  DWORD lastErrno;           /* The Windows errno from the last I/O error */

  int nRef;                  /* Number of winShm objects pointing to this */

      sqlite3_free(p->aRegion);
      sqlite3_free(p);
    }else{
      pp = &p->pNext;
    }
  }
}

/*
** The DMS lock has not yet been taken on shm file pShmNode. Attempt to
** take it now. Return SQLITE_OK if successful, or an SQLite error
** code otherwise.
**
** If the DMS cannot be locked because this is a readonly_shm=1
** connection and no other process already holds a lock, return
** SQLITE_READONLY_CANTINIT and set pShmNode->isUnlocked=1.
*/
static int winLockSharedMemory(winShmNode *pShmNode){
  int rc = winShmSystemLock(pShmNode, WINSHM_WRLCK, WIN_SHM_DMS, 1);

  if( rc==SQLITE_OK ){
    if( pShmNode->isReadonly ){
      pShmNode->isUnlocked = 1;
      winShmSystemLock(pShmNode, WINSHM_UNLCK, WIN_SHM_DMS, 1);
      return SQLITE_READONLY_CANTINIT;
    }else if( winTruncate((sqlite3_file*)&pShmNode->hFile, 0) ){
      winShmSystemLock(pShmNode, WINSHM_UNLCK, WIN_SHM_DMS, 1);
      return winLogError(SQLITE_IOERR_SHMOPEN, osGetLastError(),
                         "winLockSharedMemory", pShmNode->zFilename);
    }
  }

  if( rc==SQLITE_OK ){
    winShmSystemLock(pShmNode, WINSHM_UNLCK, WIN_SHM_DMS, 1);
  }

  return winShmSystemLock(pShmNode, WINSHM_RDLCK, WIN_SHM_DMS, 1);
}

/*
** Open the shared-memory area associated with database file pDbFd.
**
** When opening a new shared-memory file, if no other instances of that
** file are currently open, in this process or in other processes, then
** the file must be truncated to zero length or have its header cleared.
*/
static int winOpenSharedMemory(winFile *pDbFd){
  struct winShm *p;                  /* The connection to be opened */
  winShmNode *pShmNode = 0;          /* The underlying mmapped file */
  int rc = SQLITE_OK;                /* Result code */
  int rc2 = SQLITE_ERROR;            /* winOpen result code */
  winShmNode *pNew;                  /* Newly allocated winShmNode */
  int nName;                         /* Size of zName in bytes */

  assert( pDbFd->pShm==0 );    /* Not previously opened */

  /* Allocate space for the new sqlite3_shm object.  Also speculatively
  ** allocate space for a new winShmNode and filename.
  */

      pShmNode->mutex = sqlite3_mutex_alloc(SQLITE_MUTEX_FAST);
      if( pShmNode->mutex==0 ){
        rc = SQLITE_IOERR_NOMEM_BKPT;
        goto shm_open_err;
      }
    }

    if( 0==sqlite3_uri_boolean(pDbFd->zPath, "readonly_shm", 0) ){
      rc2 = winOpen(pDbFd->pVfs,
                    pShmNode->zFilename,
                    (sqlite3_file*)&pShmNode->hFile,
                    SQLITE_OPEN_WAL|SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE,
                    0);


    }
    if( rc2!=SQLITE_OK ){



      rc2 = winOpen(pDbFd->pVfs,
                    pShmNode->zFilename,
                    (sqlite3_file*)&pShmNode->hFile,
                    SQLITE_OPEN_WAL|SQLITE_OPEN_READONLY,
                    0);
      if( rc2!=SQLITE_OK ){
        rc = winLogError(rc2, osGetLastError(), "winOpenShm",
                         pShmNode->zFilename);
        goto shm_open_err;
      }
      pShmNode->isReadonly = 1;
    }




    rc = winLockSharedMemory(pShmNode);
    if( rc!=SQLITE_OK && rc!=SQLITE_READONLY_CANTINIT ) goto shm_open_err;
  }

  /* Make the new connection a child of the winShmNode */
  p->pShmNode = pShmNode;
#if defined(SQLITE_DEBUG) || defined(SQLITE_HAVE_OS_TRACE)
  p->id = pShmNode->nextShmId++;
#endif

  ** at pShmNode->pFirst. This must be done while holding the pShmNode->mutex
  ** mutex.
  */
  sqlite3_mutex_enter(pShmNode->mutex);
  p->pNext = pShmNode->pFirst;
  pShmNode->pFirst = p;
  sqlite3_mutex_leave(pShmNode->mutex);
  return rc;

  /* Jump here on any error */
shm_open_err:
  winShmSystemLock(pShmNode, WINSHM_UNLCK, WIN_SHM_DMS, 1);
  winShmPurge(pDbFd->pVfs, 0);      /* This call frees pShmNode if required */
  sqlite3_free(p);
  sqlite3_free(pNew);

  int szRegion,                   /* Size of regions */
  int isWrite,                    /* True to extend file if necessary */
  void volatile **pp              /* OUT: Mapped memory */
){
  winFile *pDbFd = (winFile*)fd;
  winShm *pShm = pDbFd->pShm;
  winShmNode *pShmNode;
  DWORD protect = PAGE_READWRITE;
  DWORD flags = FILE_MAP_WRITE | FILE_MAP_READ;
  int rc = SQLITE_OK;

  if( !pShm ){
    rc = winOpenSharedMemory(pDbFd);
    if( rc!=SQLITE_OK ) return rc;
    pShm = pDbFd->pShm;
  }
  pShmNode = pShm->pShmNode;

  sqlite3_mutex_enter(pShmNode->mutex);
  if( pShmNode->isUnlocked ){
    rc = winLockSharedMemory(pShmNode);
    if( rc!=SQLITE_OK ) goto shmpage_out;
    pShmNode->isUnlocked = 0;
  }
  assert( szRegion==pShmNode->szRegion || pShmNode->nRegion==0 );

  if( pShmNode->nRegion<=iRegion ){
    struct ShmRegion *apNew;           /* New aRegion[] array */
    int nByte = (iRegion+1)*szRegion;  /* Minimum required file size */
    sqlite3_int64 sz;                  /* Current size of wal-index file */

        pShmNode->aRegion, (iRegion+1)*sizeof(apNew[0])
    );
    if( !apNew ){
      rc = SQLITE_IOERR_NOMEM_BKPT;
      goto shmpage_out;
    }
    pShmNode->aRegion = apNew;

    if( pShmNode->isReadonly ){
      protect = PAGE_READONLY;
      flags = FILE_MAP_READ;
    }

    while( pShmNode->nRegion<=iRegion ){
      HANDLE hMap = NULL;         /* file-mapping handle */
      void *pMap = 0;             /* Mapped memory region */

#if SQLITE_OS_WINRT
      hMap = osCreateFileMappingFromApp(pShmNode->hFile.h,
          NULL, protect, nByte, NULL
      );
#elif defined(SQLITE_WIN32_HAS_WIDE)
      hMap = osCreateFileMappingW(pShmNode->hFile.h,
          NULL, protect, 0, nByte, NULL
      );
#elif defined(SQLITE_WIN32_HAS_ANSI) && SQLITE_WIN32_CREATEFILEMAPPINGA
      hMap = osCreateFileMappingA(pShmNode->hFile.h,
          NULL, protect, 0, nByte, NULL
      );
#endif
      OSTRACE(("SHM-MAP-CREATE pid=%lu, region=%d, size=%d, rc=%s\n",
               osGetCurrentProcessId(), pShmNode->nRegion, nByte,
               hMap ? "ok" : "failed"));
      if( hMap ){
        int iOffset = pShmNode->nRegion*szRegion;
        int iOffsetShift = iOffset % winSysInfo.dwAllocationGranularity;
#if SQLITE_OS_WINRT
        pMap = osMapViewOfFileFromApp(hMap, flags,
            iOffset - iOffsetShift, szRegion + iOffsetShift
        );
#else
        pMap = osMapViewOfFile(hMap, flags,
            0, iOffset - iOffsetShift, szRegion + iOffsetShift
        );
#endif
        OSTRACE(("SHM-MAP-MAP pid=%lu, region=%d, offset=%d, size=%d, rc=%s\n",
                 osGetCurrentProcessId(), pShmNode->nRegion, iOffset,
                 szRegion, pMap ? "ok" : "failed"));
      }

    int iOffset = iRegion*szRegion;
    int iOffsetShift = iOffset % winSysInfo.dwAllocationGranularity;
    char *p = (char *)pShmNode->aRegion[iRegion].pMap;
    *pp = (void *)&p[iOffsetShift];
  }else{
    *pp = 0;
  }
  if( pShmNode->isReadonly && rc==SQLITE_OK ) rc = SQLITE_READONLY;
  sqlite3_mutex_leave(pShmNode->mutex);
  return rc;
}

#else
# define winShmMap     0
# define winShmLock    0

/*
** Make sure the page is marked as clean. If it isn't clean already,
** make it so.
*/
SQLITE_PRIVATE void sqlite3PcacheMakeClean(PgHdr *p){
  assert( sqlite3PcachePageSanity(p) );
  assert( (p->flags & PGHDR_DIRTY)!=0 );
  assert( (p->flags & PGHDR_CLEAN)==0 );
  pcacheManageDirtyList(p, PCACHE_DIRTYLIST_REMOVE);
  p->flags &= ~(PGHDR_DIRTY|PGHDR_NEED_SYNC|PGHDR_WRITEABLE);
  p->flags |= PGHDR_CLEAN;
  pcacheTrace(("%p.CLEAN %d\n",p->pCache,p->pgno));
  assert( sqlite3PcachePageSanity(p) );
  if( p->nRef==0 ){
    pcacheUnpin(p);

  }
}

/*
** Make every page in the cache clean.
*/
SQLITE_PRIVATE void sqlite3PcacheCleanAll(PCache *pCache){

** WAL-INDEX FORMAT
**
** Conceptually, the wal-index is shared memory, though VFS implementations
** might choose to implement the wal-index using a mmapped file.  Because
** the wal-index is shared memory, SQLite does not support journal_mode=WAL 
** on a network filesystem.  All users of the database must be able to
** share memory.
**
** In the default unix and windows implementation, the wal-index is a mmapped
** file whose name is the database name with a "-shm" suffix added.  For that
** reason, the wal-index is sometimes called the "shm" file.
**
** The wal-index is transient.  After a crash, the wal-index can (and should
** be) reconstructed from the original WAL file.  In fact, the VFS is required
** to either truncate or zero the header of the wal-index when the last
** connection to it closes.  Because the wal-index is transient, it can
** use an architecture-specific format; it does not have to be cross-platform.
** Hence, unlike the database and WAL file formats which store all values

** WALINDEX_MAX_VERSION, then no read-transaction is opened and SQLite
** returns SQLITE_CANTOPEN.
*/
#define WAL_MAX_VERSION      3007000
#define WALINDEX_MAX_VERSION 3007000

/*
** Index numbers for various locking bytes.   WAL_NREADER is the number
** of available reader locks and should be at least 3.  The default
** is SQLITE_SHM_NLOCK==8 and  WAL_NREADER==5.
**
** Technically, the various VFSes are free to implement these locks however
** they see fit.  However, compatibility is encouraged so that VFSes can
** interoperate.  The standard implemention used on both unix and windows
** is for the index number to indicate a byte offset into the
** WalCkptInfo.aLock[] array in the wal-index header.  In other words, all
** locks are on the shm file.  The WALINDEX_LOCK_OFFSET constant (which
** should be 120) is the location in the shm file for the first locking
** byte.
*/
#define WAL_WRITE_LOCK         0
#define WAL_ALL_BUT_WRITE      1
#define WAL_CKPT_LOCK          1
#define WAL_RECOVER_LOCK       2
#define WAL_READ_LOCK(I)       (3+(I))
#define WAL_NREADER            (SQLITE_SHM_NLOCK-3)

#define WALINDEX_LOCK_OFFSET (sizeof(WalIndexHdr)*2+offsetof(WalCkptInfo,aLock))
#define WALINDEX_HDR_SIZE    (sizeof(WalIndexHdr)*2+sizeof(WalCkptInfo))

/* Size of header before each frame in wal */
#define WAL_FRAME_HDRSIZE 24

/* Size of write ahead log header, including checksum. */

#define WAL_HDRSIZE 32

/* WAL magic value. Either this value, or the same value with the least
** significant bit also set (WAL_MAGIC | 0x00000001) is stored in 32-bit
** big-endian format in the first 4 bytes of a WAL file.
**
** If the LSB is set, then the checksums for each frame within the WAL

  u8 exclusiveMode;          /* Non-zero if connection is in exclusive mode */
  u8 writeLock;              /* True if in a write transaction */
  u8 ckptLock;               /* True if holding a checkpoint lock */
  u8 readOnly;               /* WAL_RDWR, WAL_RDONLY, or WAL_SHM_RDONLY */
  u8 truncateOnCommit;       /* True to truncate WAL file on commit */
  u8 syncHeader;             /* Fsync the WAL header if true */
  u8 padToSectorBoundary;    /* Pad transactions out to the next sector */
  u8 bShmUnreliable;         /* SHM content is read-only and unreliable */
  WalIndexHdr hdr;           /* Wal-index header for current transaction */
  u32 minFrame;              /* Ignore wal frames before this one */
  u32 iReCksum;              /* On commit, recalculate checksums from here */
  const char *zWalName;      /* Name of WAL file */
  u32 nCkpt;                 /* Checkpoint sequence counter in the wal-header */
#ifdef SQLITE_DEBUG
  u8 lockError;              /* True if a locking error has occurred */

    sizeof(ht_slot)*HASHTABLE_NSLOT + HASHTABLE_NPAGE*sizeof(u32) \
)

/*
** Obtain a pointer to the iPage'th page of the wal-index. The wal-index
** is broken into pages of WALINDEX_PGSZ bytes. Wal-index pages are
** numbered from zero.
**
** If the wal-index is currently smaller the iPage pages then the size
** of the wal-index might be increased, but only if it is safe to do
** so.  It is safe to enlarge the wal-index if pWal->writeLock is true
** or pWal->exclusiveMode==WAL_HEAPMEMORY_MODE.
**
** If this call is successful, *ppPage is set to point to the wal-index
** page and SQLITE_OK is returned. If an error (an OOM or VFS error) occurs,
** then an SQLite error code is returned and *ppPage is set to 0.
*/
static int walIndexPage(Wal *pWal, int iPage, volatile u32 **ppPage){
  int rc = SQLITE_OK;

    if( pWal->exclusiveMode==WAL_HEAPMEMORY_MODE ){
      pWal->apWiData[iPage] = (u32 volatile *)sqlite3MallocZero(WALINDEX_PGSZ);
      if( !pWal->apWiData[iPage] ) rc = SQLITE_NOMEM_BKPT;
    }else{
      rc = sqlite3OsShmMap(pWal->pDbFd, iPage, WALINDEX_PGSZ, 
          pWal->writeLock, (void volatile **)&pWal->apWiData[iPage]
      );
      assert( pWal->apWiData[iPage]!=0 || rc!=SQLITE_OK || pWal->writeLock==0 );
      testcase( pWal->apWiData[iPage]==0 && rc==SQLITE_OK );
      if( (rc&0xff)==SQLITE_READONLY ){
        pWal->readOnly |= WAL_SHM_RDONLY;
        if( rc==SQLITE_READONLY ){
          rc = SQLITE_OK;
        }
      }
    }
  }

  *ppPage = pWal->apWiData[iPage];
  assert( iPage==0 || *ppPage || rc!=SQLITE_OK );
  return rc;

** the necessary locks, this routine returns SQLITE_BUSY.
*/
static int walIndexRecover(Wal *pWal){
  int rc;                         /* Return Code */
  i64 nSize;                      /* Size of log file */
  u32 aFrameCksum[2] = {0, 0};
  int iLock;                      /* Lock offset to lock for checkpoint */


  /* Obtain an exclusive lock on all byte in the locking range not already
  ** locked by the caller. The caller is guaranteed to have locked the
  ** WAL_WRITE_LOCK byte, and may have also locked the WAL_CKPT_LOCK byte.
  ** If successful, the same bytes that are locked here are unlocked before
  ** this function returns.
  */
  assert( pWal->ckptLock==1 || pWal->ckptLock==0 );
  assert( WAL_ALL_BUT_WRITE==WAL_WRITE_LOCK+1 );
  assert( WAL_CKPT_LOCK==WAL_ALL_BUT_WRITE );
  assert( pWal->writeLock );
  iLock = WAL_ALL_BUT_WRITE + pWal->ckptLock;
  rc = walLockExclusive(pWal, iLock, WAL_READ_LOCK(0)-iLock);
  if( rc==SQLITE_OK ){
    rc = walLockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
    if( rc!=SQLITE_OK ){
      walUnlockExclusive(pWal, iLock, WAL_READ_LOCK(0)-iLock);
    }
  }
  if( rc ){
    return rc;
  }

  WALTRACE(("WAL%p: recovery begin...\n", pWal));

  memset(&pWal->hdr, 0, sizeof(WalIndexHdr));

  rc = sqlite3OsFileSize(pWal->pWalFd, &nSize);
  if( rc!=SQLITE_OK ){
    goto recovery_error;

          pWal->hdr.mxFrame, pWal->zWalName
      );
    }
  }

recovery_error:
  WALTRACE(("WAL%p: recovery %s\n", pWal, rc ? "failed" : "ok"));
  walUnlockExclusive(pWal, iLock, WAL_READ_LOCK(0)-iLock);
  walUnlockExclusive(pWal, WAL_READ_LOCK(1), WAL_NREADER-1);
  return rc;
}

/*
** Close an open wal-index.
*/
static void walIndexClose(Wal *pWal, int isDelete){
  if( pWal->exclusiveMode==WAL_HEAPMEMORY_MODE || pWal->bShmUnreliable ){
    int i;
    for(i=0; i<pWal->nWiData; i++){
      sqlite3_free((void *)pWal->apWiData[i]);
      pWal->apWiData[i] = 0;
    }

  }
  if( pWal->exclusiveMode!=WAL_HEAPMEMORY_MODE ){
    sqlite3OsShmUnmap(pWal->pDbFd, isDelete);
  }
}

/* 
** Open a connection to the WAL file zWalName. The database file must 
** already be opened on connection pDbFd. The buffer that zWalName points

    testcase( pWal->szPage>=65536 );
  }

  /* The header was successfully read. Return zero. */
  return 0;
}

/*
** This is the value that walTryBeginRead returns when it needs to
** be retried.
*/
#define WAL_RETRY  (-1)

/*
** Read the wal-index header from the wal-index and into pWal->hdr.
** If the wal-header appears to be corrupt, try to reconstruct the
** wal-index from the WAL before returning.
**
** Set *pChanged to 1 if the wal-index header value in pWal->hdr is
** changed by this operation.  If pWal->hdr is unchanged, set *pChanged

  /* Ensure that page 0 of the wal-index (the page that contains the 
  ** wal-index header) is mapped. Return early if an error occurs here.
  */
  assert( pChanged );
  rc = walIndexPage(pWal, 0, &page0);
  if( rc!=SQLITE_OK ){
    assert( rc!=SQLITE_READONLY ); /* READONLY changed to OK in walIndexPage */
    if( rc==SQLITE_READONLY_CANTINIT ){
      /* The SQLITE_READONLY_CANTINIT return means that the shared-memory
      ** was openable but is not writable, and this thread is unable to
      ** confirm that another write-capable connection has the shared-memory
      ** open, and hence the content of the shared-memory is unreliable,
      ** since the shared-memory might be inconsistent with the WAL file
      ** and there is no writer on hand to fix it. */
      assert( page0==0 );
      assert( pWal->writeLock==0 );
      assert( pWal->readOnly & WAL_SHM_RDONLY );
      pWal->bShmUnreliable = 1;
      pWal->exclusiveMode = WAL_HEAPMEMORY_MODE;
      *pChanged = 1;
    }else{
      return rc; /* Any other non-OK return is just an error */
    }
  }else{
    /* page0 can be NULL if the SHM is zero bytes in size and pWal->writeLock
    ** is zero, which prevents the SHM from growing */
    testcase( page0!=0 );
  }
  assert( page0!=0 || pWal->writeLock==0 );

  /* If the first page of the wal-index has been mapped, try to read the
  ** wal-index header immediately, without holding any lock. This usually
  ** works, but may fail if the wal-index header is corrupt or currently 
  ** being modified by another thread or process.
  */
  badHdr = (page0 ? walIndexTryHdr(pWal, pChanged) : 1);

  /* If the first attempt failed, it might have been due to a race
  ** with a writer.  So get a WRITE lock and try again.
  */
  assert( badHdr==0 || pWal->writeLock==0 );
  if( badHdr ){
    if( pWal->bShmUnreliable==0 && (pWal->readOnly & WAL_SHM_RDONLY) ){
      if( SQLITE_OK==(rc = walLockShared(pWal, WAL_WRITE_LOCK)) ){
        walUnlockShared(pWal, WAL_WRITE_LOCK);
        rc = SQLITE_READONLY_RECOVERY;
      }
    }else if( SQLITE_OK==(rc = walLockExclusive(pWal, WAL_WRITE_LOCK, 1)) ){
      pWal->writeLock = 1;
      if( SQLITE_OK==(rc = walIndexPage(pWal, 0, &page0)) ){

  /* If the header is read successfully, check the version number to make
  ** sure the wal-index was not constructed with some future format that
  ** this version of SQLite cannot understand.
  */
  if( badHdr==0 && pWal->hdr.iVersion!=WALINDEX_MAX_VERSION ){
    rc = SQLITE_CANTOPEN_BKPT;
  }
  if( pWal->bShmUnreliable ){
    if( rc!=SQLITE_OK ){
      walIndexClose(pWal, 0);
      pWal->bShmUnreliable = 0;
      assert( pWal->nWiData>0 && pWal->apWiData[0]==0 );
      /* walIndexRecover() might have returned SHORT_READ if a concurrent
      ** writer truncated the WAL out from under it.  If that happens, it
      ** indicates that a writer has fixed the SHM file for us, so retry */
      if( rc==SQLITE_IOERR_SHORT_READ ) rc = WAL_RETRY;
    }
    pWal->exclusiveMode = WAL_NORMAL_MODE;
  }

  return rc;
}

/*
** Open a transaction in a connection where the shared-memory is read-only
** and where we cannot verify that there is a separate write-capable connection
** on hand to keep the shared-memory up-to-date with the WAL file.
**
** This can happen, for example, when the shared-memory is implemented by
** memory-mapping a *-shm file, where a prior writer has shut down and
** left the *-shm file on disk, and now the present connection is trying
** to use that database but lacks write permission on the *-shm file.
** Other scenarios are also possible, depending on the VFS implementation.
**
** Precondition:
**
**    The *-wal file has been read and an appropriate wal-index has been
**    constructed in pWal->apWiData[] using heap memory instead of shared
**    memory. 
**
** If this function returns SQLITE_OK, then the read transaction has
** been successfully opened. In this case output variable (*pChanged) 
** is set to true before returning if the caller should discard the
** contents of the page cache before proceeding. Or, if it returns 
** WAL_RETRY, then the heap memory wal-index has been discarded and 
** the caller should retry opening the read transaction from the 
** beginning (including attempting to map the *-shm file). 
**
** If an error occurs, an SQLite error code is returned.
*/
static int walBeginShmUnreliable(Wal *pWal, int *pChanged){
  i64 szWal;                      /* Size of wal file on disk in bytes */
  i64 iOffset;                    /* Current offset when reading wal file */
  u8 aBuf[WAL_HDRSIZE];           /* Buffer to load WAL header into */
  u8 *aFrame = 0;                 /* Malloc'd buffer to load entire frame */
  int szFrame;                    /* Number of bytes in buffer aFrame[] */
  u8 *aData;                      /* Pointer to data part of aFrame buffer */
  volatile void *pDummy;          /* Dummy argument for xShmMap */
  int rc;                         /* Return code */
  u32 aSaveCksum[2];              /* Saved copy of pWal->hdr.aFrameCksum */

  assert( pWal->bShmUnreliable );
  assert( pWal->readOnly & WAL_SHM_RDONLY );
  assert( pWal->nWiData>0 && pWal->apWiData[0] );

  /* Take WAL_READ_LOCK(0). This has the effect of preventing any
  ** writers from running a checkpoint, but does not stop them
  ** from running recovery.  */
  rc = walLockShared(pWal, WAL_READ_LOCK(0));
  if( rc!=SQLITE_OK ){
    if( rc==SQLITE_BUSY ) rc = WAL_RETRY;
    goto begin_unreliable_shm_out;
  }
  pWal->readLock = 0;

  /* Check to see if a separate writer has attached to the shared-memory area,
  ** thus making the shared-memory "reliable" again.  Do this by invoking
  ** the xShmMap() routine of the VFS and looking to see if the return
  ** is SQLITE_READONLY instead of SQLITE_READONLY_CANTINIT.
  **
  ** If the shared-memory is now "reliable" return WAL_RETRY, which will
  ** cause the heap-memory WAL-index to be discarded and the actual
  ** shared memory to be used in its place.
  **
  ** This step is important because, even though this connection is holding
  ** the WAL_READ_LOCK(0) which prevents a checkpoint, a writer might
  ** have already checkpointed the WAL file and, while the current
  ** is active, wrap the WAL and start overwriting frames that this
  ** process wants to use.
  **
  ** Once sqlite3OsShmMap() has been called for an sqlite3_file and has
  ** returned any SQLITE_READONLY value, it must return only SQLITE_READONLY
  ** or SQLITE_READONLY_CANTINIT or some error for all subsequent invocations,
  ** even if some external agent does a "chmod" to make the shared-memory
  ** writable by us, until sqlite3OsShmUnmap() has been called.
  ** This is a requirement on the VFS implementation.
   */
  rc = sqlite3OsShmMap(pWal->pDbFd, 0, WALINDEX_PGSZ, 0, &pDummy);
  assert( rc!=SQLITE_OK ); /* SQLITE_OK not possible for read-only connection */
  if( rc!=SQLITE_READONLY_CANTINIT ){
    rc = (rc==SQLITE_READONLY ? WAL_RETRY : rc);
    goto begin_unreliable_shm_out;
  }

  /* We reach this point only if the real shared-memory is still unreliable.
  ** Assume the in-memory WAL-index substitute is correct and load it
  ** into pWal->hdr.
  */
  memcpy(&pWal->hdr, (void*)walIndexHdr(pWal), sizeof(WalIndexHdr));

  /* Make sure some writer hasn't come in and changed the WAL file out
  ** from under us, then disconnected, while we were not looking.
  */
  rc = sqlite3OsFileSize(pWal->pWalFd, &szWal);
  if( rc!=SQLITE_OK ){
    goto begin_unreliable_shm_out;
  }
  if( szWal<WAL_HDRSIZE ){
    /* If the wal file is too small to contain a wal-header and the
    ** wal-index header has mxFrame==0, then it must be safe to proceed
    ** reading the database file only. However, the page cache cannot
    ** be trusted, as a read/write connection may have connected, written
    ** the db, run a checkpoint, truncated the wal file and disconnected
    ** since this client's last read transaction.  */
    *pChanged = 1;
    rc = (pWal->hdr.mxFrame==0 ? SQLITE_OK : WAL_RETRY);
    goto begin_unreliable_shm_out;
  }

  /* Check the salt keys at the start of the wal file still match. */
  rc = sqlite3OsRead(pWal->pWalFd, aBuf, WAL_HDRSIZE, 0);
  if( rc!=SQLITE_OK ){
    goto begin_unreliable_shm_out;
  }
  if( memcmp(&pWal->hdr.aSalt, &aBuf[16], 8) ){
    /* Some writer has wrapped the WAL file while we were not looking.
    ** Return WAL_RETRY which will cause the in-memory WAL-index to be
    ** rebuilt. */
    rc = WAL_RETRY;
    goto begin_unreliable_shm_out;
  }

  /* Allocate a buffer to read frames into */
  szFrame = pWal->hdr.szPage + WAL_FRAME_HDRSIZE;
  aFrame = (u8 *)sqlite3_malloc64(szFrame);
  if( aFrame==0 ){
    rc = SQLITE_NOMEM_BKPT;
    goto begin_unreliable_shm_out;
  }
  aData = &aFrame[WAL_FRAME_HDRSIZE];

  /* Check to see if a complete transaction has been appended to the
  ** wal file since the heap-memory wal-index was created. If so, the
  ** heap-memory wal-index is discarded and WAL_RETRY returned to
  ** the caller.  */
  aSaveCksum[0] = pWal->hdr.aFrameCksum[0];
  aSaveCksum[1] = pWal->hdr.aFrameCksum[1];
  for(iOffset=walFrameOffset(pWal->hdr.mxFrame+1, pWal->hdr.szPage); 
      iOffset+szFrame<=szWal; 
      iOffset+=szFrame
  ){
    u32 pgno;                   /* Database page number for frame */
    u32 nTruncate;              /* dbsize field from frame header */

    /* Read and decode the next log frame. */
    rc = sqlite3OsRead(pWal->pWalFd, aFrame, szFrame, iOffset);
    if( rc!=SQLITE_OK ) break;
    if( !walDecodeFrame(pWal, &pgno, &nTruncate, aData, aFrame) ) break;

    /* If nTruncate is non-zero, then a complete transaction has been
    ** appended to this wal file. Set rc to WAL_RETRY and break out of
    ** the loop.  */
    if( nTruncate ){
      rc = WAL_RETRY;
      break;
    }
  }
  pWal->hdr.aFrameCksum[0] = aSaveCksum[0];
  pWal->hdr.aFrameCksum[1] = aSaveCksum[1];

 begin_unreliable_shm_out:
  sqlite3_free(aFrame);
  if( rc!=SQLITE_OK ){
    int i;
    for(i=0; i<pWal->nWiData; i++){
      sqlite3_free((void*)pWal->apWiData[i]);
      pWal->apWiData[i] = 0;
    }
    pWal->bShmUnreliable = 0;
    sqlite3WalEndReadTransaction(pWal);
    *pChanged = 1;
  }
  return rc;
}

/*
** Attempt to start a read transaction.  This might fail due to a race or
** other transient condition.  When that happens, it returns WAL_RETRY to
** indicate to the caller that it is safe to retry immediately.
**
** On success return SQLITE_OK.  On a permanent failure (such an
** I/O error or an SQLITE_BUSY because another process is running
** recovery) return a positive error code.
**
** The useWal parameter is true to force the use of the WAL and disable
** the case where the WAL is bypassed because it has been completely
** checkpointed.  If useWal==0 then this routine calls walIndexReadHdr() 
** to make a copy of the wal-index header into pWal->hdr.  If the 
** wal-index header has changed, *pChanged is set to 1 (as an indication 
** to the caller that the local page cache is obsolete and needs to be 
** flushed.)  When useWal==1, the wal-index header is assumed to already
** be loaded and the pChanged parameter is unused.
**
** The caller must set the cnt parameter to the number of prior calls to
** this routine during the current read attempt that returned WAL_RETRY.
** This routine will start taking more aggressive measures to clear the
** race conditions after multiple WAL_RETRY returns, and after an excessive

  int mxI;                        /* Index of largest aReadMark[] value */
  int i;                          /* Loop counter */
  int rc = SQLITE_OK;             /* Return code  */
  u32 mxFrame;                    /* Wal frame to lock to */

  assert( pWal->readLock<0 );     /* Not currently locked */

  /* useWal may only be set for read/write connections */
  assert( (pWal->readOnly & WAL_SHM_RDONLY)==0 || useWal==0 );

  /* Take steps to avoid spinning forever if there is a protocol error.
  **
  ** Circumstances that cause a RETRY should only last for the briefest
  ** instances of time.  No I/O or other system calls are done while the
  ** locks are held, so the locks should not be held for very long. But 
  ** if we are unlucky, another process that is holding a lock might get
  ** paged out or take a page-fault that is time-consuming to resolve, 

      return SQLITE_PROTOCOL;
    }
    if( cnt>=10 ) nDelay = (cnt-9)*(cnt-9)*39;
    sqlite3OsSleep(pWal->pVfs, nDelay);
  }

  if( !useWal ){
    assert( rc==SQLITE_OK );
    if( pWal->bShmUnreliable==0 ){
      rc = walIndexReadHdr(pWal, pChanged);
    }
    if( rc==SQLITE_BUSY ){
      /* If there is not a recovery running in another thread or process
      ** then convert BUSY errors to WAL_RETRY.  If recovery is known to
      ** be running, convert BUSY to BUSY_RECOVERY.  There is a race here
      ** which might cause WAL_RETRY to be returned even if BUSY_RECOVERY
      ** would be technically correct.  But the race is benign since with
      ** WAL_RETRY this routine will be called again and will probably be

      }else if( rc==SQLITE_BUSY ){
        rc = SQLITE_BUSY_RECOVERY;
      }
    }
    if( rc!=SQLITE_OK ){
      return rc;
    }
    else if( pWal->bShmUnreliable ){
      return walBeginShmUnreliable(pWal, pChanged);
    }
  }

  assert( pWal->nWiData>0 );
  assert( pWal->apWiData[0]!=0 );
  pInfo = walCkptInfo(pWal);
  if( !useWal && pInfo->nBackfill==pWal->hdr.mxFrame
#ifdef SQLITE_ENABLE_SNAPSHOT
   && (pWal->pSnapshot==0 || pWal->hdr.mxFrame==0
     || 0==memcmp(&pWal->hdr, pWal->pSnapshot, sizeof(WalIndexHdr)))
#endif
  ){
    /* The WAL has been completely backfilled (or it is empty).
    ** and can be safely ignored.

      }else if( rc!=SQLITE_BUSY ){
        return rc;
      }
    }
  }
  if( mxI==0 ){
    assert( rc==SQLITE_BUSY || (pWal->readOnly & WAL_SHM_RDONLY)!=0 );
    return rc==SQLITE_BUSY ? WAL_RETRY : SQLITE_READONLY_CANTINIT;
  }

  rc = walLockShared(pWal, WAL_READ_LOCK(mxI));
  if( rc ){
    return rc==SQLITE_BUSY ? WAL_RETRY : rc;
  }
  /* Now that the read-lock has been obtained, check that neither the

  /* If the "last page" field of the wal-index header snapshot is 0, then
  ** no data will be read from the wal under any circumstances. Return early
  ** in this case as an optimization.  Likewise, if pWal->readLock==0, 
  ** then the WAL is ignored by the reader so return early, as if the 
  ** WAL were empty.
  */
  if( iLast==0 || (pWal->readLock==0 && pWal->bShmUnreliable==0) ){
    *piRead = 0;
    return SQLITE_OK;
  }

  /* Search the hash table or tables for an entry matching page number
  ** pgno. Each iteration of the following for() loop searches one
  ** hash table (each hash table indexes up to HASHTABLE_NPAGE frames).

#ifdef SQLITE_ENABLE_EXPENSIVE_ASSERT
  /* If expensive assert() statements are available, do a linear search
  ** of the wal-index file content. Make sure the results agree with the
  ** result obtained using the hash indexes above.  */
  {
    u32 iRead2 = 0;
    u32 iTest;
    assert( pWal->bShmUnreliable || pWal->minFrame>0 );
    for(iTest=iLast; iTest>=pWal->minFrame && iTest>0; iTest--){
      if( walFramePgno(pWal, iTest)==pgno ){
        iRead2 = iTest;
        break;
      }
    }
    assert( iRead==iRead2 );
  }

  ** locks are taken in this case). Nor should the pager attempt to
  ** upgrade to exclusive-mode following such an error.
  */
  assert( pWal->readLock>=0 || pWal->lockError );
  assert( pWal->readLock>=0 || (op<=0 && pWal->exclusiveMode==0) );

  if( op==0 ){
    if( pWal->exclusiveMode!=WAL_NORMAL_MODE ){
      pWal->exclusiveMode = WAL_NORMAL_MODE;
      if( walLockShared(pWal, WAL_READ_LOCK(pWal->readLock))!=SQLITE_OK ){
        pWal->exclusiveMode = WAL_EXCLUSIVE_MODE;
      }
      rc = pWal->exclusiveMode==WAL_NORMAL_MODE;
    }else{
      /* Already in locking_mode=NORMAL */
      rc = 0;
    }
  }else if( op>0 ){
    assert( pWal->exclusiveMode==WAL_NORMAL_MODE );
    assert( pWal->readLock>=0 );
    walUnlockShared(pWal, WAL_READ_LOCK(pWal->readLock));
    pWal->exclusiveMode = WAL_EXCLUSIVE_MODE;
    rc = 1;
  }else{
    rc = pWal->exclusiveMode==WAL_NORMAL_MODE;
  }
  return rc;
}

/* 
** Return true if the argument is non-NULL and the WAL module is using
** heap-memory for the wal-index. Otherwise, if the argument is NULL or the

** This routine calls the finalize method for that function.  The
** result of the aggregate is stored back into pMem.
**
** Return SQLITE_ERROR if the finalizer reports an error.  SQLITE_OK
** otherwise.
*/
SQLITE_PRIVATE int sqlite3VdbeMemFinalize(Mem *pMem, FuncDef *pFunc){


  sqlite3_context ctx;
  Mem t;
  assert( pFunc!=0 );
  assert( pFunc->xFinalize!=0 );
  assert( (pMem->flags & MEM_Null)!=0 || pFunc==pMem->u.pDef );
  assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
  memset(&ctx, 0, sizeof(ctx));
  memset(&t, 0, sizeof(t));
  t.flags = MEM_Null;
  t.db = pMem->db;
  ctx.pOut = &t;
  ctx.pMem = pMem;
  ctx.pFunc = pFunc;
  pFunc->xFinalize(&ctx); /* IMP: R-24505-23230 */
  assert( (pMem->flags & MEM_Dyn)==0 );
  if( pMem->szMalloc>0 ) sqlite3DbFreeNN(pMem->db, pMem->zMalloc);
  memcpy(pMem, &t, sizeof(t));
  return ctx.isError;


}

/*
** If the memory cell contains a value that must be freed by
** invoking the external callback in Mem.xDel, then this routine
** will free that value.  It also sets Mem.flags to MEM_Null.
**

/*
** Delete an entire VDBE.
*/
SQLITE_PRIVATE void sqlite3VdbeDelete(Vdbe *p){
  sqlite3 *db;

  assert( p!=0 );
  db = p->db;
  assert( sqlite3_mutex_held(db->mutex) );
  sqlite3VdbeClearObject(db, p);
  if( p->pPrev ){
    p->pPrev->pNext = p->pNext;
  }else{
    assert( db->pVdbe==p );

*/
SQLITE_PRIVATE int sqlite3WalkSelectFrom(Walker *pWalker, Select *p){
  SrcList *pSrc;
  int i;
  struct SrcList_item *pItem;

  pSrc = p->pSrc;
  assert( pSrc!=0 );
  for(i=pSrc->nSrc, pItem=pSrc->a; i>0; i--, pItem++){
    if( pItem->pSelect && sqlite3WalkSelect(pWalker, pItem->pSelect) ){
      return WRC_Abort;
    }
    if( pItem->fg.isTabFunc
     && sqlite3WalkExprList(pWalker, pItem->u1.pFuncArg)
    ){
      return WRC_Abort;

    }
  }
  return WRC_Continue;
} 

/*
** Call sqlite3WalkExpr() for every expression in Select statement p.

    ** column in the FROM clause.  This is used by the LIMIT and ORDER BY
    ** clause processing on UPDATE and DELETE statements.
    */
    case TK_ROW: {
      SrcList *pSrcList = pNC->pSrcList;
      struct SrcList_item *pItem;
      assert( pSrcList && pSrcList->nSrc==1 );
      pItem = pSrcList->a;
      assert( HasRowid(pItem->pTab) && pItem->pTab->pSelect==0 );
      pExpr->op = TK_COLUMN;
      pExpr->pTab = pItem->pTab;
      pExpr->iTable = pItem->iCursor;
      pExpr->iColumn = -1;
      pExpr->affinity = SQLITE_AFF_INTEGER;
      break;
    }

  assert( pToken );
  pNew = sqlite3ExprAlloc(db, TK_FUNCTION, pToken, 1);
  if( pNew==0 ){
    sqlite3ExprListDelete(db, pList); /* Avoid memory leak when malloc fails */
    return 0;
  }
  pNew->x.pList = pList;
  ExprSetProperty(pNew, EP_HasFunc);
  assert( !ExprHasProperty(pNew, EP_xIsSelect) );
  sqlite3ExprSetHeightAndFlags(pParse, pNew);
  return pNew;
}

/*
** Assign a variable number to an expression that encodes a wildcard

  if( !p && (pOn || pUsing) ){
    sqlite3ErrorMsg(pParse, "a JOIN clause is required before %s", 
      (pOn ? "ON" : "USING")
    );
    goto append_from_error;
  }
  p = sqlite3SrcListAppend(db, p, pTable, pDatabase);
  if( p==0 ){
    goto append_from_error;
  }
  assert( p->nSrc>0 );
  pItem = &p->a[p->nSrc-1];
  assert( pAlias!=0 );
  if( pAlias->n ){
    pItem->zAlias = sqlite3NameFromToken(db, pAlias);
  }
  pItem->pSelect = pSubquery;
  pItem->pOn = pOn;

** pWhere argument is an optional WHERE clause that restricts the
** set of rows in the view that are to be added to the ephemeral table.
*/
SQLITE_PRIVATE void sqlite3MaterializeView(
  Parse *pParse,       /* Parsing context */
  Table *pView,        /* View definition */
  Expr *pWhere,        /* Optional WHERE clause to be added */
  ExprList *pOrderBy,  /* Optional ORDER BY clause */
  Expr *pLimit,        /* Optional LIMIT clause */
  Expr *pOffset,       /* Optional OFFSET clause */
  int iCur             /* Cursor number for ephemeral table */
){
  SelectDest dest;
  Select *pSel;
  SrcList *pFrom;
  sqlite3 *db = pParse->db;
  int iDb = sqlite3SchemaToIndex(db, pView->pSchema);
  pWhere = sqlite3ExprDup(db, pWhere, 0);
  pFrom = sqlite3SrcListAppend(db, 0, 0, 0);
  if( pFrom ){
    assert( pFrom->nSrc==1 );
    pFrom->a[0].zName = sqlite3DbStrDup(db, pView->zName);
    pFrom->a[0].zDatabase = sqlite3DbStrDup(db, db->aDb[iDb].zDbSName);
    assert( pFrom->a[0].pOn==0 );
    assert( pFrom->a[0].pUsing==0 );
  }
  pSel = sqlite3SelectNew(pParse, 0, pFrom, pWhere, 0, 0, pOrderBy, 
                          SF_IncludeHidden, pLimit, pOffset);
  sqlite3SelectDestInit(&dest, SRT_EphemTab, iCur);
  sqlite3Select(pParse, pSel, &dest);
  sqlite3SelectDelete(db, pSel);
}
#endif /* !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER) */

#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) && !defined(SQLITE_OMIT_SUBQUERY)

  SrcList *pSrc,               /* the FROM clause -- which tables to scan */
  Expr *pWhere,                /* The WHERE clause.  May be null */
  ExprList *pOrderBy,          /* The ORDER BY clause.  May be null */
  Expr *pLimit,                /* The LIMIT clause.  May be null */
  Expr *pOffset,               /* The OFFSET clause.  May be null */
  char *zStmtType              /* Either DELETE or UPDATE.  For err msgs. */
){
  sqlite3 *db = pParse->db;
  Expr *pLhs = NULL;           /* LHS of IN(SELECT...) operator */
  Expr *pInClause = NULL;      /* WHERE rowid IN ( select ) */

  ExprList *pEList = NULL;     /* Expression list contaning only pSelectRowid */
  SrcList *pSelectSrc = NULL;  /* SELECT rowid FROM x ... (dup of pSrc) */
  Select *pSelect = NULL;      /* Complete SELECT tree */
  Table *pTab;

  /* Check that there isn't an ORDER BY without a LIMIT clause.
  */
  if( pOrderBy && pLimit==0 ) {
    sqlite3ErrorMsg(pParse, "ORDER BY without LIMIT on %s", zStmtType);
    sqlite3ExprDelete(pParse->db, pWhere);
    sqlite3ExprListDelete(pParse->db, pOrderBy);
    sqlite3ExprDelete(pParse->db, pLimit);
    sqlite3ExprDelete(pParse->db, pOffset);
    return 0;
  }

  /* We only need to generate a select expression if there
  ** is a limit/offset term to enforce.
  */
  if( pLimit == 0 ) {
    /* if pLimit is null, pOffset will always be null as well. */
    assert( pOffset == 0 );
    return pWhere;
  }

  /* Generate a select expression tree to enforce the limit/offset 
  ** term for the DELETE or UPDATE statement.  For example:
  **   DELETE FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
  ** becomes:
  **   DELETE FROM table_a WHERE rowid IN ( 
  **     SELECT rowid FROM table_a WHERE col1=1 ORDER BY col2 LIMIT 1 OFFSET 1
  **   );
  */

  pTab = pSrc->a[0].pTab;
  if( HasRowid(pTab) ){
    pLhs = sqlite3PExpr(pParse, TK_ROW, 0, 0);
    pEList = sqlite3ExprListAppend(
        pParse, 0, sqlite3PExpr(pParse, TK_ROW, 0, 0)
    );
  }else{
    Index *pPk = sqlite3PrimaryKeyIndex(pTab);
    if( pPk->nKeyCol==1 ){
      const char *zName = pTab->aCol[pPk->aiColumn[0]].zName;
      pLhs = sqlite3Expr(db, TK_ID, zName);
      pEList = sqlite3ExprListAppend(pParse, 0, sqlite3Expr(db, TK_ID, zName));
    }else{
      int i;
      for(i=0; i<pPk->nKeyCol; i++){
        Expr *p = sqlite3Expr(db, TK_ID, pTab->aCol[pPk->aiColumn[i]].zName);
        pEList = sqlite3ExprListAppend(pParse, pEList, p);
      }
      pLhs = sqlite3PExpr(pParse, TK_VECTOR, 0, 0);
      if( pLhs ){
        pLhs->x.pList = sqlite3ExprListDup(db, pEList, 0);
      }
    }
  }

  /* duplicate the FROM clause as it is needed by both the DELETE/UPDATE tree
  ** and the SELECT subtree. */
  pSrc->a[0].pTab = 0;
  pSelectSrc = sqlite3SrcListDup(pParse->db, pSrc, 0);
  pSrc->a[0].pTab = pTab;


  pSrc->a[0].pIBIndex = 0;


  /* generate the SELECT expression tree. */
  pSelect = sqlite3SelectNew(pParse, pEList, pSelectSrc, pWhere, 0 ,0, 
      pOrderBy,0,pLimit,pOffset

  );

  /* now generate the new WHERE rowid IN clause for the DELETE/UDPATE */
  pInClause = sqlite3PExpr(pParse, TK_IN, pLhs, 0);

  sqlite3PExprAddSelect(pParse, pInClause, pSelect);
  return pInClause;







}
#endif /* defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) */
       /*      && !defined(SQLITE_OMIT_SUBQUERY) */

/*
** Generate code for a DELETE FROM statement.
**
**     DELETE FROM table_wxyz WHERE a<5 AND b NOT NULL;
**                 \________/       \________________/
**                  pTabList              pWhere
*/
SQLITE_PRIVATE void sqlite3DeleteFrom(
  Parse *pParse,         /* The parser context */
  SrcList *pTabList,     /* The table from which we should delete things */
  Expr *pWhere,          /* The WHERE clause.  May be null */
  ExprList *pOrderBy,    /* ORDER BY clause. May be null */
  Expr *pLimit,          /* LIMIT clause. May be null */
  Expr *pOffset          /* OFFSET clause. May be null */
){
  Vdbe *v;               /* The virtual database engine */
  Table *pTab;           /* The table from which records will be deleted */
  int i;                 /* Loop counter */
  WhereInfo *pWInfo;     /* Information about the WHERE clause */
  Index *pIdx;           /* For looping over indices of the table */
  int iTabCur;           /* Cursor number for the table */

  memset(&sContext, 0, sizeof(sContext));
  db = pParse->db;
  if( pParse->nErr || db->mallocFailed ){
    goto delete_from_cleanup;
  }
  assert( pTabList->nSrc==1 );


  /* Locate the table which we want to delete.  This table has to be
  ** put in an SrcList structure because some of the subroutines we
  ** will be calling are designed to work with multiple tables and expect
  ** an SrcList* parameter instead of just a Table* parameter.
  */
  pTab = sqlite3SrcListLookup(pParse, pTabList);

# define pTrigger 0
# define isView 0
#endif
#ifdef SQLITE_OMIT_VIEW
# undef isView
# define isView 0
#endif

#ifdef SQLITE_ENABLE_UPDATE_DELETE_LIMIT
  if( !isView ){
    pWhere = sqlite3LimitWhere(
        pParse, pTabList, pWhere, pOrderBy, pLimit, pOffset, "DELETE"
    );
    pOrderBy = 0;
    pLimit = pOffset = 0;
  }
#endif

  /* If pTab is really a view, make sure it has been initialized.
  */
  if( sqlite3ViewGetColumnNames(pParse, pTab) ){
    goto delete_from_cleanup;
  }

  sqlite3BeginWriteOperation(pParse, 1, iDb);

  /* If we are trying to delete from a view, realize that view into
  ** an ephemeral table.
  */
#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
  if( isView ){
    sqlite3MaterializeView(pParse, pTab, 
        pWhere, pOrderBy, pLimit, pOffset, iTabCur
    );
    iDataCur = iIdxCur = iTabCur;
    pOrderBy = 0;
    pLimit = pOffset = 0;
  }
#endif

  /* Resolve the column names in the WHERE clause.
  */
  memset(&sNC, 0, sizeof(sNC));
  sNC.pParse = pParse;

    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "rows deleted", SQLITE_STATIC);
  }

delete_from_cleanup:
  sqlite3AuthContextPop(&sContext);
  sqlite3SrcListDelete(db, pTabList);
  sqlite3ExprDelete(db, pWhere);
#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) 
  sqlite3ExprListDelete(db, pOrderBy);
  sqlite3ExprDelete(db, pLimit);
  sqlite3ExprDelete(db, pOffset);
#endif
  sqlite3DbFree(db, aToOpen);
  return;
}
/* Make sure "isView" and other macros defined above are undefined. Otherwise
** they may interfere with compilation of other functions in this file
** (or in another file, if this file becomes part of the amalgamation).  */
#ifdef isView

      ** that point.
      **
      ** For a case-insensitive search, set variable cx to be the same as
      ** c but in the other case and search the input string for either
      ** c or cx.
      */
      if( c<=0x80 ){
        char zStop[3];
        int bMatch;
        if( noCase ){
          zStop[0] = sqlite3Toupper(c);
          zStop[1] = sqlite3Tolower(c);
          zStop[2] = 0;
        }else{
          zStop[0] = c;
          zStop[1] = 0;
        }
        while(1){
          zString += strcspn((const char*)zString, zStop);
          if( zString[0]==0 ) break;
          zString++;
          bMatch = patternCompare(zPattern,zString,pInfo,matchOther);
          if( bMatch!=SQLITE_NOMATCH ) return bMatch;
        }
      }else{
        int bMatch;
        while( (c2 = Utf8Read(zString))!=0 ){
          if( c2!=c ) continue;

      }
      if( !p ) return;
      iSkip = sqlite3VdbeMakeLabel(v);
      sqlite3VdbeAddOp2(v, OP_FkIfZero, 1, iSkip); VdbeCoverage(v);
    }

    pParse->disableTriggers = 1;
    sqlite3DeleteFrom(pParse, sqlite3SrcListDup(db, pName, 0), 0, 0, 0, 0);
    pParse->disableTriggers = 0;

    /* If the DELETE has generated immediate foreign key constraint 
    ** violations, halt the VDBE and return an error at this point, before
    ** any modifications to the schema are made. This is because statement
    ** transactions are not able to rollback schema changes.  
    **

        sqlite3VdbeAddOp3(v, OP_Column, srcTab, ipkColumn, regRowid);
      }else if( pSelect ){
        sqlite3VdbeAddOp2(v, OP_Copy, regFromSelect+ipkColumn, regRowid);
      }else{
        VdbeOp *pOp;
        sqlite3ExprCode(pParse, pList->a[ipkColumn].pExpr, regRowid);
        pOp = sqlite3VdbeGetOp(v, -1);
        assert( pOp!=0 );
        if( pOp->opcode==OP_Null && !IsVirtual(pTab) ){
          appendFlag = 1;
          pOp->opcode = OP_NewRowid;
          pOp->p1 = iDataCur;
          pOp->p2 = regRowid;
          pOp->p3 = regAutoinc;
        }
      }

  ** We return -1000000 instead of the more usual -1 simply because using
  ** -1000000 as the incorrect index into db->aDb[] is much 
  ** more likely to cause a segfault than -1 (of course there are assert()
  ** statements too, but it never hurts to play the odds).
  */
  assert( sqlite3_mutex_held(db->mutex) );
  if( pSchema ){
    for(i=0; 1; i++){
      assert( i<db->nDb );
      if( db->aDb[i].pSchema==pSchema ){
        break;
      }
    }
    assert( i>=0 && i<db->nDb );
  }
  return i;

**  (18)  If the sub-query is a compound select, then all terms of the
**        ORDER BY clause of the parent must be simple references to 
**        columns of the sub-query.
**
**  (19)  If the subquery uses LIMIT then the outer query may not
**        have a WHERE clause.
**
**  (20)  If the sub-query is a compound select, then it must not use
**        an ORDER BY clause.  Ticket #3773.  We could relax this constraint
**        somewhat by saying that the terms of the ORDER BY clause must
**        appear as unmodified result columns in the outer query.  But we
**        have other optimizations in mind to deal with that case.

**
**  (21)  If the subquery uses LIMIT then the outer query may not be
**        DISTINCT.  (See ticket [752e1646fc]).
**
**  (22)  The subquery may not be a recursive CTE.
**
**  (**)  Subsumed into restriction (17d3).  Was: If the outer query is

  /* Restriction (17): If the sub-query is a compound SELECT, then it must
  ** use only the UNION ALL operator. And none of the simple select queries
  ** that make up the compound SELECT are allowed to be aggregate or distinct
  ** queries.
  */
  if( pSub->pPrior ){
    if( pSub->pOrderBy ){
      return 0;  /* Restriction (20) */
    }
    if( isAgg || (p->selFlags & SF_Distinct)!=0 || pSrc->nSrc!=1 ){
      return 0; /* (17d1), (17d2), or (17d3) */
    }
    for(pSub1=pSub; pSub1; pSub1=pSub1->pPrior){
      testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Distinct );
      testcase( (pSub1->selFlags & (SF_Distinct|SF_Aggregate))==SF_Aggregate );
      assert( pSub->pSrc!=0 );

  ** The only way that the recursive part of a CTE can contain a compound
  ** subquery is for the subquery to be one term of a join.  But if the
  ** subquery is a join, then the flattening has already been stopped by
  ** restriction (17d3)
  */
  assert( (p->selFlags & SF_Recursive)==0 || pSub->pPrior==0 );










  /***** If we reach this point, flattening is permitted. *****/
  SELECTTRACE(1,pParse,p,("flatten %s.%p from term %d\n",
                   pSub->zSelName, pSub, iFrom));

  /* Authorize the subquery */
  pParse->zAuthContext = pSubitem->zName;
  TESTONLY(i =) sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0);

    }
  }
  return nChng;
}
#endif /* !defined(SQLITE_OMIT_SUBQUERY) || !defined(SQLITE_OMIT_VIEW) */

/*
** The pFunc is the only aggregate function in the query.  Check to see
** if the query is a candidate for the min/max optimization. 
**
** If the query is a candidate for the min/max optimization, then set
** *ppMinMax to be an ORDER BY clause to be used for the optimization
** and return either WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX depending on
** whether pFunc is a min() or max() function.

**
** If the query is not a candidate for the min/max optimization, return
** WHERE_ORDERBY_NORMAL (which must be zero).


**
** This routine must be called after aggregate functions have been
** located but before their arguments have been subjected to aggregate
** analysis.
*/
static u8 minMaxQuery(sqlite3 *db, Expr *pFunc, ExprList **ppMinMax){
  int eRet = WHERE_ORDERBY_NORMAL;      /* Return value */
  ExprList *pEList = pFunc->x.pList;    /* Arguments to agg function */


  const char *zFunc;                    /* Name of aggregate function pFunc */
  ExprList *pOrderBy;
  u8 sortOrder;

  assert( *ppMinMax==0 );
  assert( pFunc->op==TK_AGG_FUNCTION );
  if( pEList==0 || pEList->nExpr!=1 ) return eRet;
  zFunc = pFunc->u.zToken;
  if( sqlite3StrICmp(zFunc, "min")==0 ){
    eRet = WHERE_ORDERBY_MIN;
    sortOrder = SQLITE_SO_ASC;
  }else if( sqlite3StrICmp(zFunc, "max")==0 ){
    eRet = WHERE_ORDERBY_MAX;
    sortOrder = SQLITE_SO_DESC;
  }else{
    return eRet;
  }

  *ppMinMax = pOrderBy = sqlite3ExprListDup(db, pEList, 0);
  assert( pOrderBy!=0 || db->mallocFailed );
  if( pOrderBy ) pOrderBy->a[0].sortOrder = sortOrder;
  return eRet;
}

/*
** The select statement passed as the first argument is an aggregate query.
** The second argument is the associated aggregate-info object. This 
** function tests if the SELECT is of the form:

  int i, j, k;
  SrcList *pTabList;
  ExprList *pEList;
  struct SrcList_item *pFrom;
  sqlite3 *db = pParse->db;
  Expr *pE, *pRight, *pExpr;
  u16 selFlags = p->selFlags;
  u32 elistFlags = 0;

  p->selFlags |= SF_Expanded;
  if( db->mallocFailed  ){
    return WRC_Abort;
  }
  assert( p->pSrc!=0 );
  if( (selFlags & SF_Expanded)!=0 ){
    return WRC_Prune;
  }
  pTabList = p->pSrc;
  pEList = p->pEList;
  if( OK_IF_ALWAYS_TRUE(p->pWith) ){
    sqlite3WithPush(pParse, p->pWith, 0);
  }

  */
  for(k=0; k<pEList->nExpr; k++){
    pE = pEList->a[k].pExpr;
    if( pE->op==TK_ASTERISK ) break;
    assert( pE->op!=TK_DOT || pE->pRight!=0 );
    assert( pE->op!=TK_DOT || (pE->pLeft!=0 && pE->pLeft->op==TK_ID) );
    if( pE->op==TK_DOT && pE->pRight->op==TK_ASTERISK ) break;
    elistFlags |= pE->flags;
  }
  if( k<pEList->nExpr ){
    /*
    ** If we get here it means the result set contains one or more "*"
    ** operators that need to be expanded.  Loop through each expression
    ** in the result set and expand them one by one.
    */
    struct ExprList_item *a = pEList->a;
    ExprList *pNew = 0;
    int flags = pParse->db->flags;
    int longNames = (flags & SQLITE_FullColNames)!=0
                      && (flags & SQLITE_ShortColNames)==0;

    for(k=0; k<pEList->nExpr; k++){
      pE = a[k].pExpr;
      elistFlags |= pE->flags;
      pRight = pE->pRight;
      assert( pE->op!=TK_DOT || pRight!=0 );
      if( pE->op!=TK_ASTERISK
       && (pE->op!=TK_DOT || pRight->op!=TK_ASTERISK)
      ){
        /* This particular expression does not need to be expanded.
        */

          }
        }
      }
    }
    sqlite3ExprListDelete(db, pEList);
    p->pEList = pNew;
  }
  if( p->pEList ){
    if( p->pEList->nExpr>db->aLimit[SQLITE_LIMIT_COLUMN] ){
      sqlite3ErrorMsg(pParse, "too many columns in result set");
      return WRC_Abort;
    }
    if( (elistFlags & (EP_HasFunc|EP_Subquery))!=0 ){
      p->selFlags |= SF_ComplexResult;
    }
  }
  return WRC_Continue;
}

/*
** No-op routine for the parse-tree walker.
**

  Expr *pHaving;         /* The HAVING clause.  May be NULL */
  int rc = 1;            /* Value to return from this function */
  DistinctCtx sDistinct; /* Info on how to code the DISTINCT keyword */
  SortCtx sSort;         /* Info on how to code the ORDER BY clause */
  AggInfo sAggInfo;      /* Information used by aggregate queries */
  int iEnd;              /* Address of the end of the query */
  sqlite3 *db;           /* The database connection */
  ExprList *pMinMaxOrderBy = 0;  /* Added ORDER BY for min/max queries */
  u8 minMaxFlag;                 /* Flag for min/max queries */

#ifndef SQLITE_OMIT_EXPLAIN
  int iRestoreSelectId = pParse->iSelectId;
  pParse->iSelectId = pParse->iNextSelectId++;
#endif

  db = pParse->db;

    ** is not a join.  But if the outer query is not a join, then the subquery
    ** will be implemented as a co-routine and there is no advantage to
    ** flattening in that case.
    */
    if( (pSub->selFlags & SF_Aggregate)!=0 ) continue;
    assert( pSub->pGroupBy==0 );

    /* If the outer query contains a "complex" result set (that is,
    ** if the result set of the outer query uses functions or subqueries)
    ** and if the subquery contains an ORDER BY clause and if
    ** it will be implemented as a co-routine, then do not flatten.  This
    ** restriction allows SQL constructs like this:
    **
    **  SELECT expensive_function(x)
    **    FROM (SELECT x FROM tab ORDER BY y LIMIT 10);
    **
    ** The expensive_function() is only computed on the 10 rows that
    ** are output, rather than every row of the table.
    **
    ** The requirement that the outer query have a complex result set
    ** means that flattening does occur on simpler SQL constraints without
    ** the expensive_function() like:
    **
    **  SELECT x FROM (SELECT x FROM tab ORDER BY y LIMIT 10);
    */
    if( pSub->pOrderBy!=0
     && i==0
     && (p->selFlags & SF_ComplexResult)!=0
     && (pTabList->nSrc==1
         || (pTabList->a[1].fg.jointype&(JT_LEFT|JT_CROSS))!=0)
    ){
      continue;
    }

    if( flattenSubquery(pParse, p, i, isAgg) ){

        assert( pWhere==p->pWhere );
        havingToWhere(pParse, pGroupBy, pHaving, &p->pWhere);
        pWhere = p->pWhere;
      }
      sqlite3ExprAnalyzeAggregates(&sNC, pHaving);
    }
    sAggInfo.nAccumulator = sAggInfo.nColumn;
    if( p->pGroupBy==0 && p->pHaving==0 && sAggInfo.nFunc==1 ){
      minMaxFlag = minMaxQuery(db, sAggInfo.aFunc[0].pExpr, &pMinMaxOrderBy);
    }else{
      minMaxFlag = WHERE_ORDERBY_NORMAL;
    }
    for(i=0; i<sAggInfo.nFunc; i++){
      assert( !ExprHasProperty(sAggInfo.aFunc[i].pExpr, EP_xIsSelect) );
      sNC.ncFlags |= NC_InAggFunc;
      sqlite3ExprAnalyzeAggList(&sNC, sAggInfo.aFunc[i].pExpr->x.pList);
      sNC.ncFlags &= ~NC_InAggFunc;
    }
    sAggInfo.mxReg = pParse->nMem;
    if( db->mallocFailed ) goto select_end;
#if SELECTTRACE_ENABLED
    if( sqlite3SelectTrace & 0x400 ){
      int ii;
      SELECTTRACE(0x400,pParse,p,("After aggregate analysis:\n"));
      sqlite3TreeViewSelect(0, p, 0);
      for(ii=0; ii<sAggInfo.nColumn; ii++){
        sqlite3DebugPrintf("agg-column[%d] iMem=%d\n",
            ii, sAggInfo.aCol[ii].iMem);
        sqlite3TreeViewExpr(0, sAggInfo.aCol[ii].pExpr, 0);
      }
      for(ii=0; ii<sAggInfo.nFunc; ii++){
        sqlite3DebugPrintf("agg-func[%d]: iMem=%d\n",
            ii, sAggInfo.aFunc[ii].iMem);
        sqlite3TreeViewExpr(0, sAggInfo.aFunc[ii].pExpr, 0);
      }
    }
#endif


    /* Processing for aggregates with GROUP BY is very different and
    ** much more complex than aggregates without a GROUP BY.
    */
    if( pGroupBy ){
      KeyInfo *pKeyInfo;  /* Keying information for the group by clause */
      int addr1;          /* A-vs-B comparision jump */

      */
      sqlite3VdbeResolveLabel(v, addrReset);
      resetAccumulator(pParse, &sAggInfo);
      sqlite3VdbeAddOp1(v, OP_Return, regReset);
     
    } /* endif pGroupBy.  Begin aggregate queries without GROUP BY: */
    else {

#ifndef SQLITE_OMIT_BTREECOUNT
      Table *pTab;
      if( (pTab = isSimpleCount(p, &sAggInfo))!=0 ){
        /* If isSimpleCount() returns a pointer to a Table structure, then
        ** the SQL statement is of the form:
        **
        **   SELECT count(*) FROM <tbl>

        }
        sqlite3VdbeAddOp2(v, OP_Count, iCsr, sAggInfo.aFunc[0].iMem);
        sqlite3VdbeAddOp1(v, OP_Close, iCsr);
        explainSimpleCount(pParse, pTab, pBest);
      }else
#endif /* SQLITE_OMIT_BTREECOUNT */
      {
        /* This case runs if the aggregate has no GROUP BY clause.  The







        ** processing is much simpler since there is only a single row



        ** of output.











        */



        assert( p->pGroupBy==0 );


        resetAccumulator(pParse, &sAggInfo);


        /* If this query is a candidate for the min/max optimization, then


        ** minMaxFlag will have been previously set to either


        ** WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX and pMinMaxOrderBy will



        ** be an appropriate ORDER BY expression for the optimization.



        */
        assert( minMaxFlag==WHERE_ORDERBY_NORMAL || pMinMaxOrderBy!=0 );
        assert( pMinMaxOrderBy==0 || pMinMaxOrderBy->nExpr==1 );

        pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, pMinMaxOrderBy,
                                   0, minMaxFlag, 0);
        if( pWInfo==0 ){

          goto select_end;
        }
        updateAccumulator(pParse, &sAggInfo);

        if( sqlite3WhereIsOrdered(pWInfo)>0 ){
          sqlite3VdbeGoto(v, sqlite3WhereBreakLabel(pWInfo));
          VdbeComment((v, "%s() by index",
                (minMaxFlag==WHERE_ORDERBY_MIN?"min":"max")));
        }
        sqlite3WhereEnd(pWInfo);
        finalizeAggFunctions(pParse, &sAggInfo);
      }

      sSort.pOrderBy = 0;
      sqlite3ExprIfFalse(pParse, pHaving, addrEnd, SQLITE_JUMPIFNULL);
      selectInnerLoop(pParse, p, -1, 0, 0, 
                      pDest, addrEnd, addrEnd);

    }
    sqlite3VdbeResolveLabel(v, addrEnd);
    
  } /* endif aggregate query */

  if( sDistinct.eTnctType==WHERE_DISTINCT_UNORDERED ){
    explainTempTable(pParse, "DISTINCT");

  rc = (pParse->nErr>0);

  /* Control jumps to here if an error is encountered above, or upon
  ** successful coding of the SELECT.
  */
select_end:
  explainSetInteger(pParse->iSelectId, iRestoreSelectId);
  sqlite3ExprListDelete(db, pMinMaxOrderBy);
  sqlite3DbFree(db, sAggInfo.aCol);
  sqlite3DbFree(db, sAggInfo.aFunc);
#if SELECTTRACE_ENABLED
  SELECTTRACE(1,pParse,p,("end processing\n"));
  pParse->nSelectIndent--;
#endif
  return rc;

    switch( pStep->op ){
      case TK_UPDATE: {
        sqlite3Update(pParse, 
          targetSrcList(pParse, pStep),
          sqlite3ExprListDup(db, pStep->pExprList, 0), 
          sqlite3ExprDup(db, pStep->pWhere, 0), 
          pParse->eOrconf, 0, 0, 0
        );
        break;
      }
      case TK_INSERT: {
        sqlite3Insert(pParse, 
          targetSrcList(pParse, pStep),
          sqlite3SelectDup(db, pStep->pSelect, 0), 
          sqlite3IdListDup(db, pStep->pIdList), 
          pParse->eOrconf
        );
        break;
      }
      case TK_DELETE: {
        sqlite3DeleteFrom(pParse, 
          targetSrcList(pParse, pStep),
          sqlite3ExprDup(db, pStep->pWhere, 0), 0, 0, 0
        );
        break;
      }
      default: assert( pStep->op==TK_SELECT ); {
        SelectDest sDest;
        Select *pSelect = sqlite3SelectDup(db, pStep->pSelect, 0);
        sqlite3SelectDestInit(&sDest, SRT_Discard, 0);

*            onError   pTabList      pChanges             pWhere
*/
SQLITE_PRIVATE void sqlite3Update(
  Parse *pParse,         /* The parser context */
  SrcList *pTabList,     /* The table in which we should change things */
  ExprList *pChanges,    /* Things to be changed */
  Expr *pWhere,          /* The WHERE clause.  May be null */
  int onError,           /* How to handle constraint errors */
  ExprList *pOrderBy,    /* ORDER BY clause. May be null */
  Expr *pLimit,          /* LIMIT clause. May be null */
  Expr *pOffset          /* OFFSET clause. May be null */
){
  int i, j;              /* Loop counters */
  Table *pTab;           /* The table to be updated */
  int addrTop = 0;       /* VDBE instruction address of the start of the loop */
  WhereInfo *pWInfo;     /* Information about the WHERE clause */
  Vdbe *v;               /* The virtual database engine */
  Index *pIdx;           /* For looping over indices */

# define isView 0
# define tmask 0
#endif
#ifdef SQLITE_OMIT_VIEW
# undef isView
# define isView 0
#endif

#ifdef SQLITE_ENABLE_UPDATE_DELETE_LIMIT
  if( !isView ){
    pWhere = sqlite3LimitWhere(
        pParse, pTabList, pWhere, pOrderBy, pLimit, pOffset, "UPDATE"
    );
    pOrderBy = 0;
    pLimit = pOffset = 0;
  }
#endif

  if( sqlite3ViewGetColumnNames(pParse, pTab) ){
    goto update_cleanup;
  }
  if( sqlite3IsReadOnly(pParse, pTab, tmask) ){
    goto update_cleanup;
  }

  }

  /* If we are trying to update a view, realize that view into
  ** an ephemeral table.
  */
#if !defined(SQLITE_OMIT_VIEW) && !defined(SQLITE_OMIT_TRIGGER)
  if( isView ){
    sqlite3MaterializeView(pParse, pTab, 
        pWhere, pOrderBy, pLimit, pOffset, iDataCur
    );
    pOrderBy = 0;
    pLimit = pOffset = 0;
  }
#endif

  /* Resolve the column names in all the expressions in the
  ** WHERE clause.
  */
  if( sqlite3ResolveExprNames(&sNC, pWhere) ){

update_cleanup:
  sqlite3AuthContextPop(&sContext);
  sqlite3DbFree(db, aXRef); /* Also frees aRegIdx[] and aToOpen[] */
  sqlite3SrcListDelete(db, pTabList);
  sqlite3ExprListDelete(db, pChanges);
  sqlite3ExprDelete(db, pWhere);
#if defined(SQLITE_ENABLE_UPDATE_DELETE_LIMIT) 
  sqlite3ExprListDelete(db, pOrderBy);
  sqlite3ExprDelete(db, pLimit);
  sqlite3ExprDelete(db, pOffset);
#endif
  return;
}
/* Make sure "isView" and other macros defined above are undefined. Otherwise
** they may interfere with compilation of other functions in this file
** (or in another file, if this file becomes part of the amalgamation).  */
#ifdef isView
 #undef isView

** term was originally TERM_LIKE, then the parent gets TERM_LIKECOND instead.
** The TERM_LIKECOND marking indicates that the term should be coded inside
** a conditional such that is only evaluated on the second pass of a
** LIKE-optimization loop, when scanning BLOBs instead of strings.
*/
static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){
  int nLoop = 0;
  assert( pTerm!=0 );
  while( (pTerm->wtFlags & TERM_CODED)==0
      && (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin))
      && (pLevel->notReady & pTerm->prereqAll)==0
  ){
    if( nLoop && (pTerm->wtFlags & TERM_LIKE)!=0 ){
      pTerm->wtFlags |= TERM_LIKECOND;
    }else{
      pTerm->wtFlags |= TERM_CODED;
    }
    if( pTerm->iParent<0 ) break;
    pTerm = &pTerm->pWC->a[pTerm->iParent];
    assert( pTerm!=0 );
    pTerm->nChild--;
    if( pTerm->nChild!=0 ) break;
    nLoop++;
  }
}

/*

  Bitmask extraRight = 0;          /* Extra dependencies on LEFT JOIN */
  Expr *pStr1 = 0;                 /* RHS of LIKE/GLOB operator */
  int isComplete = 0;              /* RHS of LIKE/GLOB ends with wildcard */
  int noCase = 0;                  /* uppercase equivalent to lowercase */
  int op;                          /* Top-level operator.  pExpr->op */
  Parse *pParse = pWInfo->pParse;  /* Parsing context */
  sqlite3 *db = pParse->db;        /* Database connection */
  unsigned char eOp2 = 0;          /* op2 value for LIKE/REGEXP/GLOB */
  int nLeft;                       /* Number of elements on left side vector */

  if( db->mallocFailed ){
    return;
  }
  pTerm = &pWC->a[idxTerm];
  pMaskSet = &pWInfo->sMaskSet;

  ** not normally optimized for ordinary tables.  In other words, OP
  ** is one of MATCH, LIKE, GLOB, REGEXP, !=, IS, IS NOT, or NOT NULL.
  ** This information is used by the xBestIndex methods of
  ** virtual tables.  The native query optimizer does not attempt
  ** to do anything with MATCH functions.
  */
  if( pWC->op==TK_AND ){
    Expr *pRight = 0, *pLeft = 0;
    int res = isAuxiliaryVtabOperator(pExpr, &eOp2, &pLeft, &pRight);
    while( res-- > 0 ){
      int idxNew;
      WhereTerm *pNewTerm;
      Bitmask prereqColumn, prereqExpr;

      prereqExpr = sqlite3WhereExprUsage(pMaskSet, pRight);

  sqlite3DbFreeNN(db, p);
}

/*
** Free a WhereInfo structure
*/
static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){

  int i;
  assert( pWInfo!=0 );
  for(i=0; i<pWInfo->nLevel; i++){
    WhereLevel *pLevel = &pWInfo->a[i];
    if( pLevel->pWLoop && (pLevel->pWLoop->wsFlags & WHERE_IN_ABLE) ){
      sqlite3DbFree(db, pLevel->u.in.aInLoop);
    }
  }
  sqlite3WhereClauseClear(&pWInfo->sWC);
  while( pWInfo->pLoops ){
    WhereLoop *p = pWInfo->pLoops;
    pWInfo->pLoops = p->pNextLoop;
    whereLoopDelete(db, p);
  }
  sqlite3DbFreeNN(db, pWInfo);

}

/*
** Return TRUE if all of the following are true:
**
**   (1)  X has the same or lower cost that Y
**   (2)  X uses fewer WHERE clause terms than Y

        pNew->prereq = mPrereq | pTerm->prereqRight;
        rc = whereLoopInsert(pBuilder, pNew);
      }
    }
  }
#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */

  /* Loop over all indices. If there was an INDEXED BY clause, then only 
  ** consider index pProbe.  */
  for(; rc==SQLITE_OK && pProbe; 
      pProbe=(pSrc->pIBIndex ? 0 : pProbe->pNext), iSortIdx++
  ){
    if( pProbe->pPartIdxWhere!=0
     && !whereUsablePartialIndex(pSrc->iCursor, pWC, pProbe->pPartIdxWhere) ){
      testcase( pNew->iTab!=pSrc->iCursor );  /* See ticket [98d973b8f5] */
      continue;  /* Partial index inappropriate for this query */
    }
    rSize = pProbe->aiRowLogEst[0];
    pNew->u.btree.nEq = 0;

      pTab->tabFlags |= TF_StatsUsed;
    }
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
    sqlite3Stat4ProbeFree(pBuilder->pRec);
    pBuilder->nRecValid = 0;
    pBuilder->pRec = 0;
#endif




  }
  return rc;
}

#ifndef SQLITE_OMIT_VIRTUALTABLE

/*

      case 132: /* limit_opt ::= LIMIT expr COMMA expr */
{yymsp[-3].minor.yy354.pOffset = yymsp[-2].minor.yy190.pExpr; yymsp[-3].minor.yy354.pLimit = yymsp[0].minor.yy190.pExpr;}
        break;
      case 133: /* cmd ::= with DELETE FROM fullname indexed_opt where_opt */
{
  sqlite3WithPush(pParse, yymsp[-5].minor.yy285, 1);
  sqlite3SrcListIndexedBy(pParse, yymsp[-2].minor.yy185, &yymsp[-1].minor.yy0);
  sqlite3DeleteFrom(pParse,yymsp[-2].minor.yy185,yymsp[0].minor.yy72,0,0,0);
}
        break;
      case 136: /* cmd ::= with UPDATE orconf fullname indexed_opt SET setlist where_opt */
{
  sqlite3WithPush(pParse, yymsp[-7].minor.yy285, 1);
  sqlite3SrcListIndexedBy(pParse, yymsp[-4].minor.yy185, &yymsp[-3].minor.yy0);
  sqlite3ExprListCheckLength(pParse,yymsp[-1].minor.yy148,"set list"); 
  sqlite3Update(pParse,yymsp[-4].minor.yy185,yymsp[-1].minor.yy148,yymsp[0].minor.yy72,yymsp[-5].minor.yy194,0,0,0);
}
        break;
      case 137: /* setlist ::= setlist COMMA nm EQ expr */
{
  yymsp[-4].minor.yy148 = sqlite3ExprListAppend(pParse, yymsp[-4].minor.yy148, yymsp[0].minor.yy190.pExpr);
  sqlite3ExprListSetName(pParse, yymsp[-4].minor.yy148, &yymsp[-2].minor.yy0, 1);
}

      case SQLITE_BUSY_RECOVERY:      zName = "SQLITE_BUSY_RECOVERY";     break;
      case SQLITE_BUSY_SNAPSHOT:      zName = "SQLITE_BUSY_SNAPSHOT";     break;
      case SQLITE_LOCKED:             zName = "SQLITE_LOCKED";            break;
      case SQLITE_LOCKED_SHAREDCACHE: zName = "SQLITE_LOCKED_SHAREDCACHE";break;
      case SQLITE_NOMEM:              zName = "SQLITE_NOMEM";             break;
      case SQLITE_READONLY:           zName = "SQLITE_READONLY";          break;
      case SQLITE_READONLY_RECOVERY:  zName = "SQLITE_READONLY_RECOVERY"; break;
      case SQLITE_READONLY_CANTINIT:  zName = "SQLITE_READONLY_CANTINIT"; break;
      case SQLITE_READONLY_ROLLBACK:  zName = "SQLITE_READONLY_ROLLBACK"; break;
      case SQLITE_READONLY_DBMOVED:   zName = "SQLITE_READONLY_DBMOVED";  break;
      case SQLITE_INTERRUPT:          zName = "SQLITE_INTERRUPT";         break;
      case SQLITE_IOERR:              zName = "SQLITE_IOERR";             break;
      case SQLITE_IOERR_READ:         zName = "SQLITE_IOERR_READ";        break;
      case SQLITE_IOERR_SHORT_READ:   zName = "SQLITE_IOERR_SHORT_READ";  break;
      case SQLITE_IOERR_WRITE:        zName = "SQLITE_IOERR_WRITE";       break;

#define RTREE_REINSERT(p) RTREE_MINCELLS(p)
#define RTREE_MAXCELLS 51

/*
** The smallest possible node-size is (512-64)==448 bytes. And the largest
** supported cell size is 48 bytes (8 byte rowid + ten 4 byte coordinates).
** Therefore all non-root nodes must contain at least 3 entries. Since 
** 3^40 is greater than 2^64, an r-tree structure always has a depth of
** 40 or less.
*/
#define RTREE_MAX_DEPTH 40


/*
** Number of entries in the cursor RtreeNode cache.  The first entry is

  ){
    sqlite3_result_error(ctx, "Invalid argument to rtreedepth()", -1); 
  }else{
    u8 *zBlob = (u8 *)sqlite3_value_blob(apArg[0]);
    sqlite3_result_int(ctx, readInt16(zBlob));
  }
}

/*
** Context object passed between the various routines that make up the
** implementation of integrity-check function rtreecheck().
*/
typedef struct RtreeCheck RtreeCheck;
struct RtreeCheck {
  sqlite3 *db;                    /* Database handle */
  const char *zDb;                /* Database containing rtree table */
  const char *zTab;               /* Name of rtree table */
  int bInt;                       /* True for rtree_i32 table */
  int nDim;                       /* Number of dimensions for this rtree tbl */
  sqlite3_stmt *pGetNode;         /* Statement used to retrieve nodes */
  sqlite3_stmt *aCheckMapping[2]; /* Statements to query %_parent/%_rowid */
  int nLeaf;                      /* Number of leaf cells in table */
  int nNonLeaf;                   /* Number of non-leaf cells in table */
  int rc;                         /* Return code */
  char *zReport;                  /* Message to report */
  int nErr;                       /* Number of lines in zReport */
};

#define RTREE_CHECK_MAX_ERROR 100

/*
** Reset SQL statement pStmt. If the sqlite3_reset() call returns an error,
** and RtreeCheck.rc==SQLITE_OK, set RtreeCheck.rc to the error code.
*/
static void rtreeCheckReset(RtreeCheck *pCheck, sqlite3_stmt *pStmt){
  int rc = sqlite3_reset(pStmt);
  if( pCheck->rc==SQLITE_OK ) pCheck->rc = rc;
}

/*
** The second and subsequent arguments to this function are a format string
** and printf style arguments. This function formats the string and attempts
** to compile it as an SQL statement.
**
** If successful, a pointer to the new SQL statement is returned. Otherwise,
** NULL is returned and an error code left in RtreeCheck.rc.
*/
static sqlite3_stmt *rtreeCheckPrepare(
  RtreeCheck *pCheck,             /* RtreeCheck object */
  const char *zFmt, ...           /* Format string and trailing args */
){
  va_list ap;
  char *z;
  sqlite3_stmt *pRet = 0;

  va_start(ap, zFmt);
  z = sqlite3_vmprintf(zFmt, ap);

  if( pCheck->rc==SQLITE_OK ){
    if( z==0 ){
      pCheck->rc = SQLITE_NOMEM;
    }else{
      pCheck->rc = sqlite3_prepare_v2(pCheck->db, z, -1, &pRet, 0);
    }
  }

  sqlite3_free(z);
  va_end(ap);
  return pRet;
}

/*
** The second and subsequent arguments to this function are a printf()
** style format string and arguments. This function formats the string and
** appends it to the report being accumuated in pCheck.
*/
static void rtreeCheckAppendMsg(RtreeCheck *pCheck, const char *zFmt, ...){
  va_list ap;
  va_start(ap, zFmt);
  if( pCheck->rc==SQLITE_OK && pCheck->nErr<RTREE_CHECK_MAX_ERROR ){
    char *z = sqlite3_vmprintf(zFmt, ap);
    if( z==0 ){
      pCheck->rc = SQLITE_NOMEM;
    }else{
      pCheck->zReport = sqlite3_mprintf("%z%s%z", 
          pCheck->zReport, (pCheck->zReport ? "\n" : ""), z
      );
      if( pCheck->zReport==0 ){
        pCheck->rc = SQLITE_NOMEM;
      }
    }
    pCheck->nErr++;
  }
  va_end(ap);
}

/*
** This function is a no-op if there is already an error code stored
** in the RtreeCheck object indicated by the first argument. NULL is
** returned in this case.
**
** Otherwise, the contents of rtree table node iNode are loaded from
** the database and copied into a buffer obtained from sqlite3_malloc().
** If no error occurs, a pointer to the buffer is returned and (*pnNode)
** is set to the size of the buffer in bytes.
**
** Or, if an error does occur, NULL is returned and an error code left
** in the RtreeCheck object. The final value of *pnNode is undefined in
** this case.
*/
static u8 *rtreeCheckGetNode(RtreeCheck *pCheck, i64 iNode, int *pnNode){
  u8 *pRet = 0;                   /* Return value */

  assert( pCheck->rc==SQLITE_OK );
  if( pCheck->pGetNode==0 ){
    pCheck->pGetNode = rtreeCheckPrepare(pCheck,
        "SELECT data FROM %Q.'%q_node' WHERE nodeno=?", 
        pCheck->zDb, pCheck->zTab
    );
  }

  if( pCheck->rc==SQLITE_OK ){
    sqlite3_bind_int64(pCheck->pGetNode, 1, iNode);
    if( sqlite3_step(pCheck->pGetNode)==SQLITE_ROW ){
      int nNode = sqlite3_column_bytes(pCheck->pGetNode, 0);
      const u8 *pNode = (const u8*)sqlite3_column_blob(pCheck->pGetNode, 0);
      pRet = sqlite3_malloc(nNode);
      if( pRet==0 ){
        pCheck->rc = SQLITE_NOMEM;
      }else{
        memcpy(pRet, pNode, nNode);
        *pnNode = nNode;
      }
    }
    rtreeCheckReset(pCheck, pCheck->pGetNode);
    if( pCheck->rc==SQLITE_OK && pRet==0 ){
      rtreeCheckAppendMsg(pCheck, "Node %lld missing from database", iNode);
    }
  }

  return pRet;
}

/*
** This function is used to check that the %_parent (if bLeaf==0) or %_rowid
** (if bLeaf==1) table contains a specified entry. The schemas of the
** two tables are:
**
**   CREATE TABLE %_parent(nodeno INTEGER PRIMARY KEY, parentnode INTEGER)
**   CREATE TABLE %_rowid(rowid INTEGER PRIMARY KEY, nodeno INTEGER)
**
** In both cases, this function checks that there exists an entry with
** IPK value iKey and the second column set to iVal.
**
*/
static void rtreeCheckMapping(
  RtreeCheck *pCheck,             /* RtreeCheck object */
  int bLeaf,                      /* True for a leaf cell, false for interior */
  i64 iKey,                       /* Key for mapping */
  i64 iVal                        /* Expected value for mapping */
){
  int rc;
  sqlite3_stmt *pStmt;
  const char *azSql[2] = {
    "SELECT parentnode FROM %Q.'%q_parent' WHERE nodeno=?",
    "SELECT nodeno FROM %Q.'%q_rowid' WHERE rowid=?"
  };

  assert( bLeaf==0 || bLeaf==1 );
  if( pCheck->aCheckMapping[bLeaf]==0 ){
    pCheck->aCheckMapping[bLeaf] = rtreeCheckPrepare(pCheck,
        azSql[bLeaf], pCheck->zDb, pCheck->zTab
    );
  }
  if( pCheck->rc!=SQLITE_OK ) return;

  pStmt = pCheck->aCheckMapping[bLeaf];
  sqlite3_bind_int64(pStmt, 1, iKey);
  rc = sqlite3_step(pStmt);
  if( rc==SQLITE_DONE ){
    rtreeCheckAppendMsg(pCheck, "Mapping (%lld -> %lld) missing from %s table",
        iKey, iVal, (bLeaf ? "%_rowid" : "%_parent")
    );
  }else if( rc==SQLITE_ROW ){
    i64 ii = sqlite3_column_int64(pStmt, 0);
    if( ii!=iVal ){
      rtreeCheckAppendMsg(pCheck, 
          "Found (%lld -> %lld) in %s table, expected (%lld -> %lld)",
          iKey, ii, (bLeaf ? "%_rowid" : "%_parent"), iKey, iVal
      );
    }
  }
  rtreeCheckReset(pCheck, pStmt);
}

/*
** Argument pCell points to an array of coordinates stored on an rtree page.
** This function checks that the coordinates are internally consistent (no
** x1>x2 conditions) and adds an error message to the RtreeCheck object
** if they are not.
**
** Additionally, if pParent is not NULL, then it is assumed to point to
** the array of coordinates on the parent page that bound the page 
** containing pCell. In this case it is also verified that the two
** sets of coordinates are mutually consistent and an error message added
** to the RtreeCheck object if they are not.
*/
static void rtreeCheckCellCoord(
  RtreeCheck *pCheck, 
  i64 iNode,                      /* Node id to use in error messages */
  int iCell,                      /* Cell number to use in error messages */
  u8 *pCell,                      /* Pointer to cell coordinates */
  u8 *pParent                     /* Pointer to parent coordinates */
){
  RtreeCoord c1, c2;
  RtreeCoord p1, p2;
  int i;

  for(i=0; i<pCheck->nDim; i++){
    readCoord(&pCell[4*2*i], &c1);
    readCoord(&pCell[4*(2*i + 1)], &c2);

    /* printf("%e, %e\n", c1.u.f, c2.u.f); */
    if( pCheck->bInt ? c1.i>c2.i : c1.f>c2.f ){
      rtreeCheckAppendMsg(pCheck, 
          "Dimension %d of cell %d on node %lld is corrupt", i, iCell, iNode
      );
    }

    if( pParent ){
      readCoord(&pParent[4*2*i], &p1);
      readCoord(&pParent[4*(2*i + 1)], &p2);

      if( (pCheck->bInt ? c1.i<p1.i : c1.f<p1.f) 
       || (pCheck->bInt ? c2.i>p2.i : c2.f>p2.f)
      ){
        rtreeCheckAppendMsg(pCheck, 
            "Dimension %d of cell %d on node %lld is corrupt relative to parent"
            , i, iCell, iNode
        );
      }
    }
  }
}

/*
** Run rtreecheck() checks on node iNode, which is at depth iDepth within
** the r-tree structure. Argument aParent points to the array of coordinates
** that bound node iNode on the parent node.
**
** If any problems are discovered, an error message is appended to the
** report accumulated in the RtreeCheck object.
*/
static void rtreeCheckNode(
  RtreeCheck *pCheck,
  int iDepth,                     /* Depth of iNode (0==leaf) */
  u8 *aParent,                    /* Buffer containing parent coords */
  i64 iNode                       /* Node to check */
){
  u8 *aNode = 0;
  int nNode = 0;

  assert( iNode==1 || aParent!=0 );
  assert( pCheck->nDim>0 );

  aNode = rtreeCheckGetNode(pCheck, iNode, &nNode);
  if( aNode ){
    if( nNode<4 ){
      rtreeCheckAppendMsg(pCheck, 
          "Node %lld is too small (%d bytes)", iNode, nNode
      );
    }else{
      int nCell;                  /* Number of cells on page */
      int i;                      /* Used to iterate through cells */
      if( aParent==0 ){
        iDepth = readInt16(aNode);
        if( iDepth>RTREE_MAX_DEPTH ){
          rtreeCheckAppendMsg(pCheck, "Rtree depth out of range (%d)", iDepth);
          sqlite3_free(aNode);
          return;
        }
      }
      nCell = readInt16(&aNode[2]);
      if( (4 + nCell*(8 + pCheck->nDim*2*4))>nNode ){
        rtreeCheckAppendMsg(pCheck, 
            "Node %lld is too small for cell count of %d (%d bytes)", 
            iNode, nCell, nNode
        );
      }else{
        for(i=0; i<nCell; i++){
          u8 *pCell = &aNode[4 + i*(8 + pCheck->nDim*2*4)];
          i64 iVal = readInt64(pCell);
          rtreeCheckCellCoord(pCheck, iNode, i, &pCell[8], aParent);

          if( iDepth>0 ){
            rtreeCheckMapping(pCheck, 0, iVal, iNode);
            rtreeCheckNode(pCheck, iDepth-1, &pCell[8], iVal);
            pCheck->nNonLeaf++;
          }else{
            rtreeCheckMapping(pCheck, 1, iVal, iNode);
            pCheck->nLeaf++;
          }
        }
      }
    }
    sqlite3_free(aNode);
  }
}

/*
** The second argument to this function must be either "_rowid" or
** "_parent". This function checks that the number of entries in the
** %_rowid or %_parent table is exactly nExpect. If not, it adds
** an error message to the report in the RtreeCheck object indicated
** by the first argument.
*/
static void rtreeCheckCount(RtreeCheck *pCheck, const char *zTbl, i64 nExpect){
  if( pCheck->rc==SQLITE_OK ){
    sqlite3_stmt *pCount;
    pCount = rtreeCheckPrepare(pCheck, "SELECT count(*) FROM %Q.'%q%s'",
        pCheck->zDb, pCheck->zTab, zTbl
    );
    if( pCount ){
      if( sqlite3_step(pCount)==SQLITE_ROW ){
        i64 nActual = sqlite3_column_int64(pCount, 0);
        if( nActual!=nExpect ){
          rtreeCheckAppendMsg(pCheck, "Wrong number of entries in %%%s table"
              " - expected %lld, actual %lld" , zTbl, nExpect, nActual
          );
        }
      }
      pCheck->rc = sqlite3_finalize(pCount);
    }
  }
}

/*
** This function does the bulk of the work for the rtree integrity-check.
** It is called by rtreecheck(), which is the SQL function implementation.
*/
static int rtreeCheckTable(
  sqlite3 *db,                    /* Database handle to access db through */
  const char *zDb,                /* Name of db ("main", "temp" etc.) */
  const char *zTab,               /* Name of rtree table to check */
  char **pzReport                 /* OUT: sqlite3_malloc'd report text */
){
  RtreeCheck check;               /* Common context for various routines */
  sqlite3_stmt *pStmt = 0;        /* Used to find column count of rtree table */
  int bEnd = 0;                   /* True if transaction should be closed */

  /* Initialize the context object */
  memset(&check, 0, sizeof(check));
  check.db = db;
  check.zDb = zDb;
  check.zTab = zTab;

  /* If there is not already an open transaction, open one now. This is
  ** to ensure that the queries run as part of this integrity-check operate
  ** on a consistent snapshot.  */
  if( sqlite3_get_autocommit(db) ){
    check.rc = sqlite3_exec(db, "BEGIN", 0, 0, 0);
    bEnd = 1;
  }

  /* Find number of dimensions in the rtree table. */
  pStmt = rtreeCheckPrepare(&check, "SELECT * FROM %Q.%Q", zDb, zTab);
  if( pStmt ){
    int rc;
    check.nDim = (sqlite3_column_count(pStmt) - 1) / 2;
    if( check.nDim<1 ){
      rtreeCheckAppendMsg(&check, "Schema corrupt or not an rtree");
    }else if( SQLITE_ROW==sqlite3_step(pStmt) ){
      check.bInt = (sqlite3_column_type(pStmt, 1)==SQLITE_INTEGER);
    }
    rc = sqlite3_finalize(pStmt);
    if( rc!=SQLITE_CORRUPT ) check.rc = rc;
  }

  /* Do the actual integrity-check */
  if( check.nDim>=1 ){
    if( check.rc==SQLITE_OK ){
      rtreeCheckNode(&check, 0, 0, 1);
    }
    rtreeCheckCount(&check, "_rowid", check.nLeaf);
    rtreeCheckCount(&check, "_parent", check.nNonLeaf);
  }

  /* Finalize SQL statements used by the integrity-check */
  sqlite3_finalize(check.pGetNode);
  sqlite3_finalize(check.aCheckMapping[0]);
  sqlite3_finalize(check.aCheckMapping[1]);

  /* If one was opened, close the transaction */
  if( bEnd ){
    int rc = sqlite3_exec(db, "END", 0, 0, 0);
    if( check.rc==SQLITE_OK ) check.rc = rc;
  }
  *pzReport = check.zReport;
  return check.rc;
}

/*
** Usage:
**
**   rtreecheck(<rtree-table>);
**   rtreecheck(<database>, <rtree-table>);
**
** Invoking this SQL function runs an integrity-check on the named rtree
** table. The integrity-check verifies the following:
**
**   1. For each cell in the r-tree structure (%_node table), that:
**
**       a) for each dimension, (coord1 <= coord2).
**
**       b) unless the cell is on the root node, that the cell is bounded
**          by the parent cell on the parent node.
**
**       c) for leaf nodes, that there is an entry in the %_rowid 
**          table corresponding to the cell's rowid value that 
**          points to the correct node.
**
**       d) for cells on non-leaf nodes, that there is an entry in the 
**          %_parent table mapping from the cell's child node to the
**          node that it resides on.
**
**   2. That there are the same number of entries in the %_rowid table
**      as there are leaf cells in the r-tree structure, and that there
**      is a leaf cell that corresponds to each entry in the %_rowid table.
**
**   3. That there are the same number of entries in the %_parent table
**      as there are non-leaf cells in the r-tree structure, and that 
**      there is a non-leaf cell that corresponds to each entry in the 
**      %_parent table.
*/
static void rtreecheck(
  sqlite3_context *ctx, 
  int nArg, 
  sqlite3_value **apArg
){
  if( nArg!=1 && nArg!=2 ){
    sqlite3_result_error(ctx, 
        "wrong number of arguments to function rtreecheck()", -1
    );
  }else{
    int rc;
    char *zReport = 0;
    const char *zDb = (const char*)sqlite3_value_text(apArg[0]);
    const char *zTab;
    if( nArg==1 ){
      zTab = zDb;
      zDb = "main";
    }else{
      zTab = (const char*)sqlite3_value_text(apArg[1]);
    }
    rc = rtreeCheckTable(sqlite3_context_db_handle(ctx), zDb, zTab, &zReport);
    if( rc==SQLITE_OK ){
      sqlite3_result_text(ctx, zReport ? zReport : "ok", -1, SQLITE_TRANSIENT);
    }else{
      sqlite3_result_error_code(ctx, rc);
    }
    sqlite3_free(zReport);
  }
}


/*
** Register the r-tree module with database handle db. This creates the
** virtual table module "rtree" and the debugging/analysis scalar 
** function "rtreenode".
*/
SQLITE_PRIVATE int sqlite3RtreeInit(sqlite3 *db){
  const int utf8 = SQLITE_UTF8;
  int rc;

  rc = sqlite3_create_function(db, "rtreenode", 2, utf8, 0, rtreenode, 0, 0);
  if( rc==SQLITE_OK ){
    rc = sqlite3_create_function(db, "rtreedepth", 1, utf8, 0,rtreedepth, 0, 0);
  }
  if( rc==SQLITE_OK ){
    rc = sqlite3_create_function(db, "rtreecheck", -1, utf8, 0,rtreecheck, 0,0);
  }
  if( rc==SQLITE_OK ){
#ifdef SQLITE_RTREE_INT_ONLY
    void *c = (void *)RTREE_COORD_INT32;
#else
    void *c = (void *)RTREE_COORD_REAL32;
#endif
    rc = sqlite3_create_module_v2(db, "rtree", &rtreeModule, c, 0);

typedef struct DbpageTable DbpageTable;
typedef struct DbpageCursor DbpageCursor;

struct DbpageCursor {
  sqlite3_vtab_cursor base;       /* Base class.  Must be first */
  int pgno;                       /* Current page number */
  int mxPgno;                     /* Last page to visit on this scan */
  Pager *pPager;                  /* Pager being read/written */
  DbPage *pPage1;                 /* Page 1 of the database */
  int iDb;                        /* Index of database to analyze */
  int szPage;                     /* Size of each page in bytes */
};

struct DbpageTable {
  sqlite3_vtab base;              /* Base class.  Must be first */
  sqlite3 *db;                    /* The database */
};


/* Columns */
#define DBPAGE_COLUMN_PGNO    0
#define DBPAGE_COLUMN_DATA    1
#define DBPAGE_COLUMN_SCHEMA  2



/*
** Connect to or create a dbpagevfs virtual table.
*/
static int dbpageConnect(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVtab,
  char **pzErr
){
  DbpageTable *pTab = 0;
  int rc = SQLITE_OK;













  rc = sqlite3_declare_vtab(db, 
          "CREATE TABLE x(pgno INTEGER PRIMARY KEY, data BLOB, schema HIDDEN)");
  if( rc==SQLITE_OK ){
    pTab = (DbpageTable *)sqlite3_malloc64(sizeof(DbpageTable));
    if( pTab==0 ) rc = SQLITE_NOMEM_BKPT;
  }

  assert( rc==SQLITE_OK || pTab==0 );
  if( rc==SQLITE_OK ){

    memset(pTab, 0, sizeof(DbpageTable));
    pTab->db = db;


  }

  *ppVtab = (sqlite3_vtab*)pTab;
  return rc;
}

/*
** Disconnect from or destroy a dbpagevfs virtual table.
*/
static int dbpageDisconnect(sqlite3_vtab *pVtab){
  sqlite3_free(pVtab);
  return SQLITE_OK;
}

/*
** idxNum:
**
**     0     schema=main, full table scan
**     1     schema=main, pgno=?1
**     2     schema=?1, full table scan
**     3     schema=?1, pgno=?2
*/
static int dbpageBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
  int i;
  int iPlan = 0;

  /* If there is a schema= constraint, it must be honored.  Report a
  ** ridiculously large estimated cost if the schema= constraint is
  ** unavailable
  */
  for(i=0; i<pIdxInfo->nConstraint; i++){
    struct sqlite3_index_constraint *p = &pIdxInfo->aConstraint[i];
    if( p->iColumn!=DBPAGE_COLUMN_SCHEMA ) continue;
    if( p->op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
    if( !p->usable ){
      /* No solution.  Use the default SQLITE_BIG_DBL cost */
      pIdxInfo->estimatedRows = 0x7fffffff;
      return SQLITE_OK;
    }
    iPlan = 2;
    pIdxInfo->aConstraintUsage[i].argvIndex = 1;
    pIdxInfo->aConstraintUsage[i].omit = 1;
    break;
  }

  /* If we reach this point, it means that either there is no schema=
  ** constraint (in which case we use the "main" schema) or else the
  ** schema constraint was accepted.  Lower the estimated cost accordingly
  */
  pIdxInfo->estimatedCost = 1.0e6;

  /* Check for constraints against pgno */
  for(i=0; i<pIdxInfo->nConstraint; i++){
    struct sqlite3_index_constraint *p = &pIdxInfo->aConstraint[i];
    if( p->usable && p->iColumn<=0 && p->op==SQLITE_INDEX_CONSTRAINT_EQ ){
      pIdxInfo->estimatedRows = 1;
      pIdxInfo->idxFlags = SQLITE_INDEX_SCAN_UNIQUE;
      pIdxInfo->estimatedCost = 1.0;

      pIdxInfo->aConstraintUsage[i].argvIndex = iPlan ? 2 : 1;
      pIdxInfo->aConstraintUsage[i].omit = 1;
      iPlan |= 1;
      break;
    }
  }
  pIdxInfo->idxNum = iPlan;

  if( pIdxInfo->nOrderBy>=1
   && pIdxInfo->aOrderBy[0].iColumn<=0
   && pIdxInfo->aOrderBy[0].desc==0
  ){
    pIdxInfo->orderByConsumed = 1;
  }
  return SQLITE_OK;

}

/*
** Close a dbpagevfs cursor.
*/
static int dbpageClose(sqlite3_vtab_cursor *pCursor){
  DbpageCursor *pCsr = (DbpageCursor *)pCursor;
  if( pCsr->pPage1 ) sqlite3PagerUnrefPageOne(pCsr->pPage1);
  sqlite3_free(pCsr);
  return SQLITE_OK;
}

/*
** Move a dbpagevfs cursor to the next entry in the file.
*/
static int dbpageNext(sqlite3_vtab_cursor *pCursor){
  int rc = SQLITE_OK;
  DbpageCursor *pCsr = (DbpageCursor *)pCursor;
  pCsr->pgno++;
  return rc;
}

static int dbpageEof(sqlite3_vtab_cursor *pCursor){
  DbpageCursor *pCsr = (DbpageCursor *)pCursor;
  return pCsr->pgno > pCsr->mxPgno;
}

/*
** idxNum:
**
**     0     schema=main, full table scan
**     1     schema=main, pgno=?1
**     2     schema=?1, full table scan
**     3     schema=?1, pgno=?2
**
** idxStr is not used
*/
static int dbpageFilter(
  sqlite3_vtab_cursor *pCursor, 
  int idxNum, const char *idxStr,
  int argc, sqlite3_value **argv
){
  DbpageCursor *pCsr = (DbpageCursor *)pCursor;
  DbpageTable *pTab = (DbpageTable *)pCursor->pVtab;
  int rc;
  sqlite3 *db = pTab->db;
  Btree *pBt;

  /* Default setting is no rows of result */
  pCsr->pgno = 1; 
  pCsr->mxPgno = 0;

  if( idxNum & 2 ){
    const char *zSchema;
    assert( argc>=1 );
    zSchema = (const char*)sqlite3_value_text(argv[0]);
    pCsr->iDb = sqlite3FindDbName(db, zSchema);
    if( pCsr->iDb<0 ) return SQLITE_OK;
  }else{
    pCsr->iDb = 0;
  }
  pBt = db->aDb[pCsr->iDb].pBt;
  if( pBt==0 ) return SQLITE_OK;
  pCsr->pPager = sqlite3BtreePager(pBt);
  pCsr->szPage = sqlite3BtreeGetPageSize(pBt);
  pCsr->mxPgno = sqlite3BtreeLastPage(pBt);
  if( idxNum & 1 ){
    assert( argc>(idxNum>>1) );
    pCsr->pgno = sqlite3_value_int(argv[idxNum>>1]);
    if( pCsr->pgno<1 || pCsr->pgno>pCsr->mxPgno ){
      pCsr->pgno = 1;
      pCsr->mxPgno = 0;
    }else{
      pCsr->mxPgno = pCsr->pgno;
    }
  }else{
    assert( pCsr->pgno==1 );

  }
  if( pCsr->pPage1 ) sqlite3PagerUnrefPageOne(pCsr->pPage1);
  rc = sqlite3PagerGet(pCsr->pPager, 1, &pCsr->pPage1, 0);
  return rc;
}

static int dbpageColumn(
  sqlite3_vtab_cursor *pCursor, 
  sqlite3_context *ctx, 
  int i
){
  DbpageCursor *pCsr = (DbpageCursor *)pCursor;

  int rc = SQLITE_OK;
  switch( i ){
    case 0: {           /* pgno */
      sqlite3_result_int(ctx, pCsr->pgno);
      break;
    }
    case 1: {           /* data */
      DbPage *pDbPage = 0;
      rc = sqlite3PagerGet(pCsr->pPager, pCsr->pgno, (DbPage**)&pDbPage, 0);
      if( rc==SQLITE_OK ){
        sqlite3_result_blob(ctx, sqlite3PagerGetData(pDbPage), pCsr->szPage,
                            SQLITE_TRANSIENT);
      }
      sqlite3PagerUnref(pDbPage);
      break;
    }
    default: {          /* schema */
      sqlite3 *db = sqlite3_context_db_handle(ctx);
      sqlite3_result_text(ctx, db->aDb[pCsr->iDb].zDbSName, -1, SQLITE_STATIC);
      break;
    }
  }
  return SQLITE_OK;
}

static int dbpageRowid(sqlite3_vtab_cursor *pCursor, sqlite_int64 *pRowid){
  DbpageCursor *pCsr = (DbpageCursor *)pCursor;
  *pRowid = pCsr->pgno;
  return SQLITE_OK;
}

static int dbpageUpdate(
  sqlite3_vtab *pVtab,
  int argc,
  sqlite3_value **argv,
  sqlite_int64 *pRowid
){
  DbpageTable *pTab = (DbpageTable *)pVtab;
  Pgno pgno;
  DbPage *pDbPage = 0;
  int rc = SQLITE_OK;
  char *zErr = 0;
  const char *zSchema;
  int iDb;
  Btree *pBt;
  Pager *pPager;
  int szPage;

  if( argc==1 ){
    zErr = "cannot delete";
    goto update_fail;
  }
  pgno = sqlite3_value_int(argv[0]);




  if( (Pgno)sqlite3_value_int(argv[1])!=pgno ){
    zErr = "cannot insert";
    goto update_fail;
  }
  zSchema = (const char*)sqlite3_value_text(argv[4]);
  iDb = zSchema ? sqlite3FindDbName(pTab->db, zSchema) : -1;
  if( iDb<0 ){
    zErr = "no such schema";
    goto update_fail;
  }
  pBt = pTab->db->aDb[iDb].pBt;
  if( pgno<1 || pBt==0 || pgno>(int)sqlite3BtreeLastPage(pBt) ){
    zErr = "bad page number";
    goto update_fail;
  }
  szPage = sqlite3BtreeGetPageSize(pBt);
  if( sqlite3_value_type(argv[3])!=SQLITE_BLOB 
   || sqlite3_value_bytes(argv[3])!=szPage
  ){
    zErr = "bad page value";
    goto update_fail;
  }
  pPager = sqlite3BtreePager(pBt);
  rc = sqlite3PagerGet(pPager, pgno, (DbPage**)&pDbPage, 0);
  if( rc==SQLITE_OK ){
    rc = sqlite3PagerWrite(pDbPage);
    if( rc==SQLITE_OK ){
      memcpy(sqlite3PagerGetData(pDbPage),
             sqlite3_value_blob(argv[3]),
             szPage);
    }
  }
  sqlite3PagerUnref(pDbPage);
  return rc;

update_fail:
  sqlite3_free(pVtab->zErrMsg);
  pVtab->zErrMsg = sqlite3_mprintf("%s", zErr);
  return SQLITE_ERROR;
}

/* Since we do not know in advance which database files will be
** written by the sqlite_dbpage virtual table, start a write transaction
** on them all.
*/
static int dbpageBegin(sqlite3_vtab *pVtab){
  DbpageTable *pTab = (DbpageTable *)pVtab;
  sqlite3 *db = pTab->db;
  int i;
  for(i=0; i<db->nDb; i++){
    Btree *pBt = db->aDb[i].pBt;
    if( pBt ) sqlite3BtreeBeginTrans(pBt, 1);
  }
  return SQLITE_OK;
}


/*
** Invoke this routine to register the "dbpage" virtual table module
*/
SQLITE_PRIVATE int sqlite3DbpageRegister(sqlite3 *db){
  static sqlite3_module dbpage_module = {
    0,                            /* iVersion */
    dbpageConnect,                /* xCreate */
    dbpageConnect,                /* xConnect */
    dbpageBestIndex,              /* xBestIndex */
    dbpageDisconnect,             /* xDisconnect */
    dbpageDisconnect,             /* xDestroy */
    dbpageOpen,                   /* xOpen - open a cursor */
    dbpageClose,                  /* xClose - close a cursor */
    dbpageFilter,                 /* xFilter - configure scan constraints */
    dbpageNext,                   /* xNext - advance a cursor */
    dbpageEof,                    /* xEof - check for end of scan */
    dbpageColumn,                 /* xColumn - read data */
    dbpageRowid,                  /* xRowid - read data */
    dbpageUpdate,                 /* xUpdate */
    dbpageBegin,                  /* xBegin */
    0,                            /* xSync */
    0,                            /* xCommit */
    0,                            /* xRollback */
    0,                            /* xFindMethod */
    0,                            /* xRename */
    0,                            /* xSavepoint */
    0,                            /* xRelease */

static void fts5SourceIdFunc(
  sqlite3_context *pCtx,          /* Function call context */
  int nArg,                       /* Number of args */
  sqlite3_value **apUnused        /* Function arguments */
){
  assert( nArg==0 );
  UNUSED_PARAM2(nArg, apUnused);
  sqlite3_result_text(pCtx, "fts5: 2017-11-14 19:34:22 00ec95fcd02bb415dabd7f25fee24856d45d6916c18b2728e97e9bb9b8322ba3", -1, SQLITE_TRANSIENT);
}

static int fts5Init(sqlite3 *db){
  static const sqlite3_module fts5Mod = {
    /* iVersion      */ 2,
    /* xCreate       */ fts5CreateMethod,
    /* xConnect      */ fts5ConnectMethod,

#endif
  return rc;
}
#endif /* SQLITE_CORE */
#endif /* !defined(SQLITE_CORE) || defined(SQLITE_ENABLE_STMTVTAB) */

/************** End of stmt.c ************************************************/
#if __LINE__!=206322
#undef SQLITE_SOURCE_ID
#define SQLITE_SOURCE_ID      "2017-11-14 19:34:22 00ec95fcd02bb415dabd7f25fee24856d45d6916c18b2728e97e9bb9b832alt2"
#endif
/* Return the source-id for this library */
SQLITE_API const char *sqlite3_sourceid(void){ return SQLITE_SOURCE_ID; }
/************************** End of sqlite3.c ******************************/

** been edited in any way since it was last checked in, then the last
** four hexadecimal digits of the hash may be modified.
**
** See also: [sqlite3_libversion()],
** [sqlite3_libversion_number()], [sqlite3_sourceid()],
** [sqlite_version()] and [sqlite_source_id()].
*/
#define SQLITE_VERSION        "3.22.0"
#define SQLITE_VERSION_NUMBER 3022000
#define SQLITE_SOURCE_ID      "2017-11-14 19:34:22 00ec95fcd02bb415dabd7f25fee24856d45d6916c18b2728e97e9bb9b8322ba3"

/*
** 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

#define SQLITE_LOCKED_SHAREDCACHE      (SQLITE_LOCKED |  (1<<8))
#define SQLITE_BUSY_RECOVERY           (SQLITE_BUSY   |  (1<<8))
#define SQLITE_BUSY_SNAPSHOT           (SQLITE_BUSY   |  (2<<8))
#define SQLITE_CANTOPEN_NOTEMPDIR      (SQLITE_CANTOPEN | (1<<8))
#define SQLITE_CANTOPEN_ISDIR          (SQLITE_CANTOPEN | (2<<8))
#define SQLITE_CANTOPEN_FULLPATH       (SQLITE_CANTOPEN | (3<<8))
#define SQLITE_CANTOPEN_CONVPATH       (SQLITE_CANTOPEN | (4<<8))
#define SQLITE_CANTOPEN_DIRTYWAL       (SQLITE_CANTOPEN | (5<<8))
#define SQLITE_CORRUPT_VTAB            (SQLITE_CORRUPT | (1<<8))
#define SQLITE_READONLY_RECOVERY       (SQLITE_READONLY | (1<<8))
#define SQLITE_READONLY_CANTLOCK       (SQLITE_READONLY | (2<<8))
#define SQLITE_READONLY_ROLLBACK       (SQLITE_READONLY | (3<<8))
#define SQLITE_READONLY_DBMOVED        (SQLITE_READONLY | (4<<8))
#define SQLITE_READONLY_CANTINIT       (SQLITE_READONLY | (5<<8))
#define SQLITE_ABORT_ROLLBACK          (SQLITE_ABORT | (2<<8))
#define SQLITE_CONSTRAINT_CHECK        (SQLITE_CONSTRAINT | (1<<8))
#define SQLITE_CONSTRAINT_COMMITHOOK   (SQLITE_CONSTRAINT | (2<<8))
#define SQLITE_CONSTRAINT_FOREIGNKEY   (SQLITE_CONSTRAINT | (3<<8))
#define SQLITE_CONSTRAINT_FUNCTION     (SQLITE_CONSTRAINT | (4<<8))
#define SQLITE_CONSTRAINT_NOTNULL      (SQLITE_CONSTRAINT | (5<<8))
#define SQLITE_CONSTRAINT_PRIMARYKEY   (SQLITE_CONSTRAINT | (6<<8))

** CAPI3REF: OS Interface Object
**
** An instance of the sqlite3_vfs object defines the interface between
** the SQLite core and the underlying operating system.  The "vfs"
** in the name of the object stands for "virtual file system".  See
** the [VFS | VFS documentation] for further information.
**
** The VFS interface is sometimes extended by adding new methods onto
** the end.  Each time such an extension occurs, the iVersion field
** is incremented.  The iVersion value started out as 1 in
** SQLite [version 3.5.0] on [dateof:3.5.0], then increased to 2
** with SQLite [version 3.7.0] on [dateof:3.7.0], and then increased
** to 3 with SQLite [version 3.7.6] on [dateof:3.7.6].  Additional fields
** may be appended to the sqlite3_vfs object and the iVersion value
** may increase again in future versions of SQLite.
** Note that the structure
** of the sqlite3_vfs object changes in the transition from
** SQLite [version 3.5.9] to [version 3.6.0] on [dateof:3.6.0]
** and yet the iVersion field was not modified.

**
** The szOsFile field is the size of the subclassed [sqlite3_file]
** structure used by this VFS.  mxPathname is the maximum length of
** a pathname in this VFS.
**
** Registered sqlite3_vfs objects are kept on a linked list formed by
** the pNext pointer.  The [sqlite3_vfs_register()]