}

/*
** Issue a warning and give the user an opportunity to abandon out
** if a \r\n line ending is seen in a text file.
*/
static void cr_warning(const Blob *p, const char *zFilename){
  int nCrNl = 0;          /* Number of \r\n line endings seen */
  const unsigned char *z; /* File text */
  int n;                  /* Size of the file in bytes */
  int lastNl = 0;         /* Characters since last \n */
  int i;                  /* Loop counter */
  char *zMsg;             /* Warning message */
  Blob fname;             /* Relative pathname of the file */
  static int allOk = 0;   /* Set to true to disable this routine */

  if( allOk ) return;
  z = (unsigned char*)blob_buffer(p);
  n = blob_size(p);
  for(i=0; i<n-1; i++){
    unsigned char c = z[i];
    if( c==0 ) return;   /* It's binary */
    if( c=='\n' ){
      if( i>0 && z[i-1]=='\r' ){
        nCrNl = 1;
        if( i>8191 ) break;
      }
      lastNl = 0;
    }else{
      lastNl++;
      /* Binary if any line longer than 8191, see looks_like_binary() */
      if( lastNl>8191 ) return;
    }
  }
  if( nCrNl ){
    Blob ans;
    char cReply;

    file_relative_name(zFilename, &fname, 0);
    blob_zero(&ans);
    zMsg = mprintf(
         "%s contains CR/NL line endings; commit anyhow (yes/no/all)?",

*/
#define DIFF_CANNOT_COMPUTE_BINARY \
    "cannot compute difference between binary files\n"

#define DIFF_CANNOT_COMPUTE_SYMLINK \
    "cannot compute difference between symlink and regular file\n"


#endif /* INTERFACE */

/*
** Maximum length of a line in a text file.  (8192)
*/
#define LENGTH_MASK_SZ  13
#define LENGTH_MASK     ((1<<LENGTH_MASK_SZ)-1)

  int nFrom;         /* Number of lines in aFrom[] */
  DLine *aTo;        /* File on right side of the diff */
  int nTo;           /* Number of lines in aTo[] */
};

/*
** Return an array of DLine objects containing a pointer to the
** start of each line and a hash of that line.  The lower 
** bits of the hash store the length of each line.
**
** Trailing whitespace is removed from each line.  2010-08-20:  Not any
** more.  If trailing whitespace is ignored, the "patch" command gets
** confused by the diff output.  Ticket [a9f7b23c2e376af5b0e5b]
**
** Return 0 if the file is binary or contains a line that is

  /* Return results */
  *pnLine = nLine;
  return a;
}

/*

** Returns non-zero if the specified content appears to be binary or
** contains a line that is too long.

*/
int looks_like_binary(const Blob *pContent){
  const char *z = blob_buffer(pContent);
  int n = blob_size(pContent);
  int i, j;


  /* Count the number of lines.  Allocate space to hold
  ** the returned array.
  */
  for(i=j=0; i<n; i++, j++){
    int c = z[i];
    if( c==0 ) return 1;  /* \000 byte in a file -> binary */
    if( c=='\n' ){



      if( j>LENGTH_MASK ){
        return 1;   /* Very long line -> binary */
      }
      j = 0;
    }
  }
  if( j>LENGTH_MASK ){
    return 1;  /* Very long line -> binary */
  }
  return 0;   /* No problems seen -> not binary */
}

/*
** Return true if two DLine elements are identical.
*/
static int same_dline(DLine *pA, DLine *pB){
  return pA->h==pB->h && memcmp(pA->z,pB->z,pA->h & LENGTH_MASK)==0;

  blob_append(pOut, "\n", 1);
}

/*
** Add two line numbers to the beginning of an output line for a context
** diff.  One or of the other of the two numbers might be zero, which means
** to leave that number field blank.  The "html" parameter means to format
** the output for HTML.  
*/
static void appendDiffLineno(Blob *pOut, int lnA, int lnB, int html){
  if( html ) blob_append(pOut, "<span class=\"diffln\">", -1);
  if( lnA>0 ){
    blob_appendf(pOut, "%6d ", lnA);
  }else{
    blob_append(pOut, "       ", 7);

  DContext *p,      /* The difference */
  Blob *pOut,       /* Output a context diff to here */
  int nContext,     /* Number of lines of context */
  int showLn,       /* Show line numbers */
  int html          /* Render as HTML */
){
  DLine *A;     /* Left side of the diff */
  DLine *B;     /* Right side of the diff */  
  int a = 0;    /* Index of next line in A[] */
  int b = 0;    /* Index of next line in B[] */
  int *R;       /* Array of COPY/DELETE/INSERT triples */
  int r;        /* Index into R[] */
  int nr;       /* Number of COPY/DELETE/INSERT triples to process */
  int mxr;      /* Maximum value for r */
  int na, nb;   /* Number of lines shown from A and B */

  sqlite3_snprintf(7, &p->zLine[p->n], "%5d ", ln+1);
  p->n += 6;
  sbsWriteHtml(p, "</span>");
  p->zLine[p->n++] = ' ';
}

/*
** The two text segments zLeft and zRight are known to be different on 
** both ends, but they might have  a common segment in the middle.  If
** they do not have a common segment, return 0.  If they do have a large
** common segment, return 1 and before doing so set:
**
**   aLCS[0] = start of the common segment in zLeft
**   aLCS[1] = end of the common segment in zLeft
**   aLCS[2] = start of the common segment in zLeft

    if( p->iStart==p->iEnd ){
      p->iStart = p->iStart2;
      p->iEnd = p->iEnd2;
      p->zStart = p->zStart2;
      p->iStart2 = 0;
      p->iEnd2 = 0;
    }
    if( p->iStart==p->iEnd ) p->iStart = p->iEnd = -1; 
    sbsWriteText(p, pRight, SBS_NEWLINE);
    return;
  }

  /* If all else fails, show a single big change between left and right */
  sbsWriteLineno(p, lnLeft);
  p->iStart2 = p->iEnd2 = 0;

  DContext *p,       /* The computed diff */
  Blob *pOut,        /* Write the results here */
  int nContext,      /* Number of lines of context around each change */
  int width,         /* Width of each column of output */
  int escHtml        /* True to generate HTML output */
){
  DLine *A;     /* Left side of the diff */
  DLine *B;     /* Right side of the diff */  
  int a = 0;    /* Index of next line in A[] */
  int b = 0;    /* Index of next line in B[] */
  int *R;       /* Array of COPY/DELETE/INSERT triples */
  int r;        /* Index into R[] */
  int nr;       /* Number of COPY/DELETE/INSERT triples to process */
  int mxr;      /* Maximum value for r */
  int na, nb;   /* Number of lines shown from A and B */

    /* Show the differences */
    for(i=0; i<nr; i++){
      unsigned char *alignment;
      ma = R[r+i*3+1];   /* Lines on left but not on right */
      mb = R[r+i*3+2];   /* Lines on right but not on left */

      /* If the gap between the current diff and then next diff within the
      ** same block is not too great, then render them as if they are a 
      ** single diff. */
      while( i<nr-1 && smallGap(&R[r+i*3]) ){
        i++;
        m = R[r+i*3];
        ma += R[r+i*3+1] + m;
        mb += R[r+i*3+2] + m;
      }

** If there are two or more possible answers of the same length, the
** returned sequence should be the one closest to the center of the
** input range.
**
** Ideally, the common sequence should be the longest possible common
** sequence.  However, an exact computation of LCS is O(N*N) which is
** way too slow for larger files.  So this routine uses an O(N)
** heuristic approximation based on hashing that usually works about 
** as well.  But if the O(N) algorithm doesn't get a good solution
** and N is not too large, we fall back to an exact solution by
** calling optimalLCS().
*/
static void longestCommonSequence(
  DContext *p,               /* Two files being compared */
  int iS1, int iE1,          /* Range of lines in p->aFrom[] */

  iEXb = iEXp = iS1;
  iSYb = iSYp = iS2;
  iEYb = iEYp = iS2;
  mid = (iE1 + iS1)/2;
  for(i=iS1; i<iE1; i++){
    int limit = 0;
    j = p->aTo[p->aFrom[i].h % p->nTo].iHash;
    while( j>0 
      && (j-1<iS2 || j>=iE2 || !same_dline(&p->aFrom[i], &p->aTo[j-1]))
    ){
      if( limit++ > 10 ){
        j = 0;
        break;
      }
      j = p->aTo[j-1].iNext;

    optimalLCS(p, iS1, iE1, iS2, iE2, piSX, piEX, piSY, piEY);
  }else{
    *piSX = iSXb;
    *piSY = iSYb;
    *piEX = iEXb;
    *piEY = iEYb;
  }
  /* printf("LCS(%d..%d/%d..%d) = %d..%d/%d..%d\n", 
     iS1, iE1, iS2, iE2, *piSX, *piEX, *piSY, *piEY);  */
}

/*
** Expand the size of aEdit[] array to hold at least nEdit elements.
*/
static void expandEdit(DContext *p, int nEdit){

        return;
      }
    }
    if( nCopy==0 && nDel==0 ){
      p->aEdit[p->nEdit-1] += nIns;
      return;
    }
  }  
  if( p->nEdit+3>p->nEditAlloc ){
    expandEdit(p, p->nEdit*2 + 15);
    if( p->aEdit==0 ) return;
  }
  p->aEdit[p->nEdit++] = nCopy;
  p->aEdit[p->nEdit++] = nDel;
  p->aEdit[p->nEdit++] = nIns;

  return w;
}

/*
** Generate a report of the differences between files pA and pB.
** If pOut is not NULL then a unified diff is appended there.  It
** is assumed that pOut has already been initialized.  If pOut is
** NULL, then a pointer to an array of integers is returned.  
** The integers come in triples.  For each triple,
** the elements are the number of lines copied, the number of
** lines deleted, and the number of lines inserted.  The vector
** is terminated by a triple of all zeros.
**
** This diff utility does not work on binary files.  If a binary
** file is encountered, 0 is returned and pOut is written with
** text "cannot compute difference between binary files".
*/
int *text_diff(
  Blob *pA_Blob,   /* FROM file */
  Blob *pB_Blob,   /* TO file */
  Blob *pOut,      /* Write diff here if not NULL */
  u64 diffFlags    /* DIFF_* flags defined above */
){
  int ignoreEolWs; /* Ignore whitespace at the end of lines */
  int nContext;    /* Amount of context to display */	
  DContext c;

  if( diffFlags & DIFF_INVERT ){
    Blob *pTemp = pA_Blob;
    pA_Blob = pB_Blob;
    pB_Blob = pTemp;
  }

    free(c.aTo);
    return c.aEdit;
  }
}

/*
** Process diff-related command-line options and return an appropriate
** "diffFlags" integer.  
**
**   --brief                Show filenames only    DIFF_BRIEF
**   --context|-c N         N lines of context.    DIFF_CONTEXT_MASK
**   --html                 Format for HTML        DIFF_HTML
**   --invert               Invert the diff        DIFF_INVERT
**   --linenum|-n           Show line numbers      DIFF_LINENO
**   --noopt                Disable optimization   DIFF_NOOPT

  /* Clear out the diff results */
  fossil_free(p->c.aEdit);
  p->c.aEdit = 0;
  p->c.nEdit = 0;
  p->c.nEditAlloc = 0;

  /* Clear out the from file */
  free(p->c.aFrom);    

  /* Return no errors */
  return 0;
}


/*

    fossil_panic("unable to retrieve content of artifact #%d", rid);
  }
  db_multi_exec("CREATE TEMP TABLE ok(rid INTEGER PRIMARY KEY)");
  if( iLimit<=0 ) iLimit = 1000000000;
  compute_direct_ancestors(mid, iLimit);
  annotation_start(p, &toAnnotate);

  db_prepare(&q, 
    "SELECT mlink.fid,"
    "       (SELECT uuid FROM blob WHERE rid=mlink.%s),"
    "       date(event.mtime), "
    "       coalesce(event.euser,event.user) "
    "  FROM ancestor, mlink, event"
    " WHERE mlink.fnid=%d"
    "   AND mlink.mid=ancestor.rid"

  while( db_step(&q)==SQLITE_ROW ){
    int pid = db_column_int(&q, 0);
    const char *zUuid = db_column_text(&q, 1);
    const char *zDate = db_column_text(&q, 2);
    const char *zUser = db_column_text(&q, 3);
    if( webLabel ){
      zLabel = mprintf(
          "<a href='%R/info/%s' target='infowindow'>%.10s</a> %s %13.13s", 
          zUuid, zUuid, zDate, zUser
      );
    }else{
      zLabel = mprintf("%.10s %s %13.13s", zUuid, zDate, zUser);
    }
    p->nVers++;
    p->azVers = fossil_realloc(p->azVers, p->nVers*sizeof(p->azVers[0]) );

  if( showLog ){
    for(i=0; i<ann.nVers; i++){
      printf("version %3d: %s\n", i+1, ann.azVers[i]);
    }
    printf("---------------------------------------------------\n");
  }
  for(i=0; i<ann.nOrig; i++){
    fossil_print("%s: %.*s\n", 
                 ann.aOrig[i].zSrc, ann.aOrig[i].n, ann.aOrig[i].z);
  }
}