** command zDiffCmd to do the diffing.
**
** When using an external diff program, zBinGlob contains the GLOB patterns
** for file names to treat as binary.  If fIncludeBinary is zero, these files
** will be skipped in addition to files that may contain binary content.
*/
static void diff_one_against_disk(
  const char *zFrom,        /* Version tag for the "before" file */
  const char *zDiffCmd,     /* Use this "diff" command */
  const char *zBinGlob,     /* Treat file names matching this as binary */
  int fIncludeBinary,       /* Include binary files for external diff */
  u64 diffFlags,            /* Diff control flags */
  const char *zFileTreeName /* Name of the file to be diffed */
){
  Blob fname;
  Blob content;
  int isLink;
  int isBin;
  file_tree_name(zFileTreeName, &fname, 0, 1);
  historical_version_of_file(zFrom, blob_str(&fname), &content, &isLink, 0,

** command zDiffCmd to do the diffing.
**
** When using an external diff program, zBinGlob contains the GLOB patterns
** for file names to treat as binary.  If fIncludeBinary is zero, these files
** will be skipped in addition to files that may contain binary content.
*/
static void diff_one_two_versions(
  const char *zFrom,            /* Version tag for the "before" file */
  const char *zTo,              /* Version tag for the "after" file */
  const char *zDiffCmd,         /* Use this "diff" command */
  const char *zBinGlob,         /* GLOB pattern for files that are binary */
  int fIncludeBinary,           /* True to show binary files */
  u64 diffFlags,                /* Diff flags */
  const char *zFileTreeName     /* Name of the file to be diffed */
){
  char *zName;
  Blob fname;
  Blob v1, v2;
  int isLink1, isLink2;
  int isBin1, isBin2;
  if( diffFlags & DIFF_BRIEF ) return;

  const char *zFrom;         /* Source version number */
  const char *zTo;           /* Target 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 */
  u64 diffFlags = 0;         /* Flags to control the DIFF */


  if( find_option("tk",0,0)!=0 ){
    diff_tk("diff", 2);
    return;
  }
  isGDiff = g.argv[1][0]=='g';
  isInternDiff = find_option("internal","i",0)!=0;

    if( !isInternDiff ){
      zDiffCmd = diff_command_external(isGDiff);
    }
    zBinGlob = diff_get_binary_glob();
    fIncludeBinary = diff_include_binary_files();
    verify_all_options();
    if( g.argc>=3 ){
      int i;
      for(i=2; i<g.argc; i++){
        diff_one_against_disk(zFrom, zDiffCmd, zBinGlob, fIncludeBinary,
                              diffFlags, g.argv[i]);
      }
    }else{
      diff_all_against_disk(zFrom, zDiffCmd, zBinGlob, fIncludeBinary,
                            diffFlags);
    }
  }else if( zFrom==0 ){
    fossil_fatal("must use --from if --to is present");
  }else{
    db_find_and_open_repository(0, 0);
    if( !isInternDiff ){
      zDiffCmd = diff_command_external(isGDiff);
    }
    zBinGlob = diff_get_binary_glob();
    fIncludeBinary = diff_include_binary_files();
    verify_all_options();
    if( g.argc>=3 ){
      int i;
      for(i=2; i<g.argc; i++){
        diff_one_two_versions(zFrom, zTo, zDiffCmd, zBinGlob, fIncludeBinary,
                              diffFlags, g.argv[i]);
      }
    }else{
      diff_all_two_versions(zFrom, zTo, zDiffCmd, zBinGlob, fIncludeBinary,
                            diffFlags);
    }
  }
}