// NewInflater creates a new io.ReadCloser that satisfies reads by decompressing data read from r. // The implementation buffers input and may read more data than necessary from r. // It is the caller's responsibility to call Close on the ReadCloser when done. func NewInflater(r io.Reader) (io.ReadCloser, os.Error) { z := new(reader) if fr, ok := r.(flate.Reader); ok { z.r = fr } else { z.r = bufio.NewReader(r) } _, err := io.ReadFull(z.r, z.scratch[0:2]) if err != nil { return nil, err } h := uint(z.scratch[0])<<8 | uint(z.scratch[1]) if (z.scratch[0]&0x0f != zlibDeflate) || (h%31 != 0) { return nil, HeaderError } if z.scratch[1]&0x20 != 0 { // BUG(nigeltao): The zlib package does not implement the FDICT flag. return nil, UnsupportedError } z.digest = adler32.New() z.inflater = flate.NewInflater(z.r) return z, nil }
func (z *Inflater) readHeader(save bool) os.Error { _, err := io.ReadFull(z.r, z.buf[0:10]) if err != nil { return err } if z.buf[0] != gzipID1 || z.buf[1] != gzipID2 || z.buf[2] != gzipDeflate { return HeaderError } z.flg = z.buf[3] if save { z.Mtime = get4(z.buf[4:8]) // z.buf[8] is xfl, ignored z.OS = z.buf[9] } z.digest.Reset() z.digest.Write(z.buf[0:10]) if z.flg&flagExtra != 0 { n, err := z.read2() if err != nil { return err } data := make([]byte, n) if _, err = io.ReadFull(z.r, data); err != nil { return err } if save { z.Extra = data } } var s string if z.flg&flagName != 0 { if s, err = z.readString(); err != nil { return err } if save { z.Name = s } } if z.flg&flagComment != 0 { if s, err = z.readString(); err != nil { return err } if save { z.Comment = s } } if z.flg&flagHdrCrc != 0 { n, err := z.read2() if err != nil { return err } sum := z.digest.Sum32() & 0xFFFF if n != sum { return HeaderError } } z.digest.Reset() z.inflater = flate.NewInflater(z.r) return nil }