const char *zTo;           /* Target version number */
  const char *zCheckin;      /* Check-in version number */
  const char *zBranch;       /* Branch to diff */
  const char *zDiffCmd = 0;  /* External diff command. NULL for internal diff */
  const char *zBinGlob = 0;  /* Treat file names matching this as binary */
  int fIncludeBinary = 0;    /* Include binary files for external diff */
  int againstUndo = 0;       /* Diff against files in the undo buffer */
  u64 diffFlags = 0;         /* Flags to control the DIFF */
  FileDirList *pFileDir = 0; /* Restrict the diff to these files */
  DiffConfig DCfg;           /* Diff configuration object */

  if( find_option("tk",0,0)!=0 || has_option("tclsh") ){
    diff_tk("diff", 2);
    return;
  }
  isGDiff = g.argv[1][0]=='g';
  isInternDiff = find_option("internal","i",0)!=0;
  zFrom = find_option("from", "r", 1);
  zTo = find_option("to", 0, 1);
  zCheckin = find_option("checkin", 0, 1);
  zBranch = find_option("branch", 0, 1);
  againstUndo = find_option("undo",0,0)!=0;
  diffFlags = diff_options(&DCfg);
  verboseFlag = find_option("verbose","v",0)!=0;
  if( !verboseFlag ){
    verboseFlag = find_option("new-file","N",0)!=0; /* deprecated */
  }
  if( verboseFlag ) diffFlags |= DIFF_VERBOSE;
  if( againstUndo && ( zFrom!=0 || zTo!=0 || zCheckin!=0 || zBranch!=0) ){
    fossil_fatal("cannot use --undo together with --from, --to, --checkin,"
                 " or --branch");
  }
  if( zBranch ){
    if( zTo || zFrom || zCheckin ){
      fossil_fatal("cannot use --from, --to, or --checkin with --branch");

    db_must_be_within_tree();
  }else if( zFrom==0 ){
    fossil_fatal("must use --from if --to is present");
  }else{
    db_find_and_open_repository(0, 0);
  }
  if( !isInternDiff
   && (diffFlags & DIFF_HTML)==0 /* External diff can't generate HTML */
  ){
    zDiffCmd = find_option("command", 0, 1);
    if( zDiffCmd==0 ) zDiffCmd = diff_command_external(isGDiff);
  }
  zBinGlob = diff_get_binary_glob();
  fIncludeBinary = diff_include_binary_files();
  determine_exec_relative_option(1);

      "SELECT uuid FROM blob, plink"
      " WHERE plink.cid=%d AND plink.isprim AND plink.pid=blob.rid",
      ridTo);
    if( zFrom==0 ){
      fossil_fatal("check-in %s has no parent", zTo);
    }
  }
  diff_begin(diffFlags);
  if( againstUndo ){
    if( db_lget_int("undo_available",0)==0 ){
      fossil_print("No undo or redo is available\n");
      return;
    }
    diff_against_undo(zDiffCmd, zBinGlob, fIncludeBinary,
                      diffFlags, pFileDir);
  }else if( zTo==0 ){
    diff_against_disk(zFrom, zDiffCmd, zBinGlob, fIncludeBinary,
                      diffFlags, pFileDir, 0);
  }else{
    diff_two_versions(zFrom, zTo, zDiffCmd, zBinGlob, fIncludeBinary,
                      diffFlags, pFileDir);
  }
  if( pFileDir ){
    int i;
    for(i=0; pFileDir[i].zName; i++){
      if( pFileDir[i].nUsed==0
       && strcmp(pFileDir[0].zName,".")!=0
       && !file_isdir(g.argv[i+2], ExtFILE)
      ){
        fossil_fatal("not found: '%s'", g.argv[i+2]);
      }
      fossil_free(pFileDir[i].zName);
    }
    fossil_free(pFileDir);
  }
  diff_end(diffFlags, 0);
  if ( diffFlags & DIFF_NUMSTAT ){
    fossil_print("%10d %10d TOTAL over %d changed files\n", 
                 g.diffCnt[1], g.diffCnt[2], g.diffCnt[0]);
  }
}

/*
** WEBPAGE: vpatch