// OpenFromFiler is like Open but it accepts an arbitrary backing storage // provided by filer. func OpenFromFiler(filer lldb.Filer, opts *Options) (db *DB, err error) { opts = opts.clone() opts._ACID = _ACIDFull defer func() { if db != nil { db.opts = opts } }() defer func() { lock := opts.lock if err != nil && lock != nil { lock.Close() db = nil } if err != nil { if db != nil { db.Close() db = nil } } }() name := filer.Name() if err = opts.check(name, false, true); err != nil { return } sz, err := filer.Size() if err != nil { return } if sz%16 != 0 { return nil, &os.PathError{Op: "kv.Open:", Path: name, Err: fmt.Errorf("file size %d(%#x) is not 0 (mod 16)", sz, sz)} } var b [16]byte if n, err := filer.ReadAt(b[:], 0); n != 16 || err != nil { return nil, &os.PathError{Op: "kv.Open.ReadAt", Path: name, Err: err} } var h header if err = h.rd(b[:]); err != nil { return nil, &os.PathError{Op: "kv.Open:validate header", Path: name, Err: err} } db = &DB{lock: opts.lock} if filer, err = opts.acidFiler(db, filer); err != nil { return nil, err } db.filer = filer switch h.ver { default: return nil, &os.PathError{Op: "kv.Open", Path: name, Err: fmt.Errorf("unknown/unsupported kv file format version %#x", h.ver)} case 0x00: if _, err = open00(name, db); err != nil { return nil, err } } db.root, err = lldb.OpenBTree(db.alloc, opts.Compare, 1) db.wal = opts.wal if opts.VerifyDbAfterOpen { err = verifyAllocator(db.alloc) } return }