** rollback all the filesystem changes.
*/
static int undoNeedRollback = 0;

/*
** Save the current content of the file zPathname so that it
** will be undoable.  The name is relative to the root of the
** tree.
** tree. Any file bigger than "limit" will not be stored in
** the undo table, and cause this function to return 1.
*/
void undo_save(const char *zPathname){
int undo_save(const char *zPathname, i64 limit){
  char *zFullname;
  Blob content;
  int existsFlag;
  int isLink;
  Stmt q;
  int result = 0;
  i64 size;

  if( !undoActive ) return;
  if( !undoActive ) return 0;
  zFullname = mprintf("%s%s", g.zLocalRoot, zPathname);
  existsFlag = file_wd_size(zFullname)>=0;
  size = file_wd_size(zFullname);
  existsFlag = size>=0;
  isLink = file_wd_islink(zFullname);
  if( limit>=0 && size>limit ){
    result = 1;
  }else{
  db_prepare(&q,
    "INSERT OR IGNORE INTO"
    "   undo(pathname,redoflag,existsflag,isExe,isLink,content)"
    " VALUES(%Q,0,%d,%d,%d,:c)",
    zPathname, existsFlag, file_wd_isexe(zFullname), isLink
  );
  if( existsFlag ){
    if( isLink ){
      blob_read_link(&content, zFullname); 
    }else{
      blob_read_from_file(&content, zFullname);
    }
    db_bind_blob(&q, ":c", &content);
  }
    db_prepare(&q,
      "INSERT OR IGNORE INTO"
      "   undo(pathname,redoflag,existsflag,isExe,isLink,content)"
      " VALUES(%Q,0,%d,%d,%d,:c)",
      zPathname, size>=0, file_wd_isexe(zFullname), isLink
    );
    if( existsFlag ){
      if( isLink ){
        blob_read_link(&content, zFullname);
      }else{
        blob_read_from_file(&content, zFullname);
      }
      db_bind_blob(&q, ":c", &content);
    }
  free(zFullname);
  db_step(&q);
  db_finalize(&q);
  if( existsFlag ){
    blob_reset(&content);
  }
    db_step(&q);
    db_finalize(&q);
    if( existsFlag ){
      blob_reset(&content);
    }
  }
  free(zFullname);
  undoNeedRollback = 1;
  return result;
}

/*
** Make the current state of stashid undoable.
*/
void undo_save_stash(int stashid){
  const char *zDb = db_name("localdb");