Fossil

  int existsFlag;
  Stmt q;

  if( !undoActive ) return;
  zFullname = mprintf("%s/%s", g.zLocalRoot, zPathname);
  existsFlag = file_size(zFullname)>=0;
  db_prepare(&q,
    "REPLACE INTO undo(pathname,redoflag,existsflag,content)"
    "INSERT OR IGNORE INTO undo(pathname,redoflag,existsflag,content)"
    " VALUES(%Q,0,%d,:c)",
    zPathname, existsFlag
  );
  if( existsFlag ){
    blob_read_from_file(&content, zFullname);
    db_bind_blob(&q, ":c", &content);
  }