// NewReader returns a new table reader for the file. Closing the reader will
// close the file.
func NewReader(f File, o *db.Options) *Reader {
r := &Reader{
file: f,
comparer: o.GetComparer(),
verifyChecksums: o.GetVerifyChecksums(),
}
if f == nil {
r.err = errors.New("leveldb/table: nil file")
return r
}
stat, err := f.Stat()
if err != nil {
r.err = fmt.Errorf("leveldb/table: invalid table (could not stat file): %v", err)
return r
}
var footer [footerLen]byte
if stat.Size() < int64(len(footer)) {
r.err = errors.New("leveldb/table: invalid table (file size is too small)")
return r
}
_, err = f.ReadAt(footer[:], stat.Size()-int64(len(footer)))
if err != nil && err != io.EOF {
r.err = fmt.Errorf("leveldb/table: invalid table (could not read footer): %v", err)
return r
}
if string(footer[footerLen-len(magic):footerLen]) != magic {
r.err = errors.New("leveldb/table: invalid table (bad magic number)")
return r
}
// Ignore the metaindex.
_, n := decodeBlockHandle(footer[:])
if n == 0 {
r.err = errors.New("leveldb/table: invalid table (bad metaindex block handle)")
return r
}
// Read the index into memory.
indexBH, n := decodeBlockHandle(footer[n:])
if n == 0 {
r.err = errors.New("leveldb/table: invalid table (bad index block handle)")
return r
}
r.index, r.err = r.readBlock(indexBH)
return r
}
