sqlite3_randomness(15, &zBuf[j]);
    for(i=0; i<15; i++, j++){
      zBuf[j] = (char)zChars[ ((unsigned char)zBuf[j])%(sizeof(zChars)-1) ];
    }
    zBuf[j] = 0;
  }while( access(zBuf,0)==0 );
}


/*
** Return true if a file named zName exists and has identical content
** to the blob pContent.  If zName does not exist or if the content is
** different in any way, then return false.
*/
int file_is_the_same(Blob *pContent, const char *zName){
  i64 iSize;
  int rc;
  Blob onDisk;

  iSize = file_size(zName);
  if( iSize<0 ) return 0;
  if( iSize!=blob_size(pContent) ) return 0;
  blob_read_from_file(&onDisk, zName);
  rc = blob_compare(&onDisk, pContent);
  blob_reset(&onDisk);
  return rc==0;
}