if( zOut ){
    blob_write_to_file(&tarball, zOut);
    blob_reset(&tarball);
  }
}

/*
** Check to see if the input string is of the form:
** Check to see if the input string is of one of the following
** two the forms:
**
**        check-in-name/filename.ext
**        check-in-name/filename.ext                       (1)
**        tag-name/check-in-name/filename.txt              (2)
**
** In other words, check to see if the input contains a single '/'
** character that separates a valid check-in name from a filename.
** In other words, check to see if the input string contains either
** a check-in name or a tag-name and a check-in name separated by
** a slash.  There must be either 1 or 2 "/" characters.  In the
** second form, tag-name must be an individual tag (not a branch-tag)
** that is found on the check-in identified by the check-in-name.
**
** If the condition is true, return the check-in name and set the
** input string to be the filename.
** If the condition is true, then:
**
**   *  Make *pzName point to the fielname suffix only
**   *  return a copy of the check-in name in memory from mprintf().
**
** If the condition is false, return NULL
** If the condition is false, leave *pzName unchanged and return either
** NULL or an empty string.  Normally NULL is returned, however an
** empty string is returned for format (2) if check-in-name does not
** match tag-name.
**
** Format (2) is specifically designed to allow URLs like this:
**
**      /tarball/release/UUID/PROJECT.tar.gz
**
** Such URLs will pass through most anti-robot filters because of the
** "/tarball/release" prefix will match the suggested "robot-exception"
** pattern and can still refer to an historic release rather than just
** the most recent release.
*/
char *tar_uuid_from_name(char **pzName){
  char *zName = *pzName;
  int i, n;
  for(i=n=0; zName[i]; i++){
  char *zName = *pzName;      /* Original input */
  int n1 = 0;                 /* Bytes in first prefix (tag-name) */
  int n2 = 0;                 /* Bytes in second prefix (check-in-name) */
  int n = 0;                  /* max(n1,n2) */
  int i;                      /* Loop counter */
  for(i=n1=n2=0; zName[i]; i++){
    if( zName[i]=='/' ){
      if( n==0 ) n = i;
      else return 0;
    }
  }
  if( n==0 ) return 0;
  if( zName[n+1]==0 ) return 0;
  zName[n] = 0;
  *pzName = fossil_strdup(&zName[n+1]);
  return zName;
}

      if( n1==0 ){
        n = n1 = i;
      }else if( n2==0 ){
        n = n2 = i;
      }else{
        return 0;   /* More than two "/" characters seen */
      }
    }
  }
  if( n1==0 ){
    return 0;    /* No prefix of any kind */
  }
  if( zName[n+1]==0 ){
    return 0;    /* No filename suffix */
  }
  if( n2==0 ){
    /* Format (1): check-in name only.  The check-in-name is not verified */
    zName[n1] = 0;
    *pzName = fossil_strdup(&zName[n1+1]);
    return zName;
  }else if( n2>n1+1 ){
    /* Format (2): tag-name/check-in-name.  Verify that check-in-name is real
    ** and that the check-in has the tag named by tag-name.
    */
    char *zCkin = mprintf("%.*s", n2-n1-1, &zName[n1+1]);
    char *zTag;
    int rid = symbolic_name_to_rid(zCkin,"ci");
    int hasTag;
    if( rid<=0 ){
      fossil_free(zCkin);
      return fossil_strdup("");
    }
    zTag = mprintf("%.*s", n1, zName);
    hasTag = db_exists(
      "SELECT 1 FROM tagxref, tag"
      " WHERE tagxref.rid=%d"
      "   AND tag.tagid=tagxref.tagid"
      "   AND tagxref.tagtype=1"
      "   AND tag.tagname='sym-%q'",
      rid, zTag
    );
    fossil_free(zTag);
    if( !hasTag ){
      fossil_free(zCkin);
      return fossil_strdup("");
    }
    *pzName = fossil_strdup(&zName[n2+1]);
    return zCkin;             
  }else{
    return 0;
  }
}

/*
** WEBPAGE: tarball
** URL: /tarball/[VERSION/]NAME.tar.gz
** URL: /tarball/NAME.tar.gz
**  or: /tarball/VERSION/NAME.tar.gz
**  or: /tarball/TAG/VERSION/NAME.tar.gz
**
** Generate a compressed tarball for the check-in specified by VERSION.
** The tarball is called NAME.tar.gz and has a top-level directory called
** NAME.
** NAME.  If TAG is provided, then VERSION must hold TAG or else an error
** is returned.
**
** The optional VERSION element defaults to "trunk" per the r= rules below.
** All of the following URLs are equivalent:
**
**      /tarball/release/xyz.tar.gz
**      /tarball?r=release&name=xyz.tar.gz
**      /tarball/xyz.tar.gz?r=release