diff --git a/src/compress/gzip/gunzip.go b/src/compress/gzip/gunzip.go index 5d072878ee..926bae88c7 100644 --- a/src/compress/gzip/gunzip.go +++ b/src/compress/gzip/gunzip.go @@ -9,6 +9,7 @@ package gzip import ( "bufio" "compress/flate" + "encoding/binary" "errors" "hash/crc32" "io" @@ -33,6 +34,16 @@ var ( ErrHeader = errors.New("gzip: invalid header") ) +var le = binary.LittleEndian + +// noEOF converts io.EOF to io.ErrUnexpectedEOF. +func noEOF(err error) error { + if err == io.EOF { + return io.ErrUnexpectedEOF + } + return err +} + // The gzip file stores a header giving metadata about the compressed file. // That header is exposed as the fields of the Writer and Reader structs. // @@ -99,7 +110,8 @@ func (z *Reader) Reset(r io.Reader) error { } else { z.r = bufio.NewReader(r) } - return z.readHeader(true) + z.Header, z.err = z.readHeader() + return z.err } // Multistream controls whether the reader supports multistream files. @@ -122,14 +134,13 @@ func (z *Reader) Multistream(ok bool) { z.multistream = ok } -// GZIP (RFC 1952) is little-endian, unlike ZLIB (RFC 1950). -func get4(p []byte) uint32 { - return uint32(p[0]) | uint32(p[1])<<8 | uint32(p[2])<<16 | uint32(p[3])<<24 -} - +// readString reads a NUL-terminated string from z.r. +// It treats the bytes read as being encoded as ISO 8859-1 (Latin-1) and +// will output a string encoded using UTF-8. +// This method always updates z.digest with the data read. func (z *Reader) readString() (string, error) { var err error - needconv := false + needConv := false for i := 0; ; i++ { if i >= len(z.buf) { return "", ErrHeader @@ -139,11 +150,14 @@ func (z *Reader) readString() (string, error) { return "", err } if z.buf[i] > 0x7f { - needconv = true + needConv = true } if z.buf[i] == 0 { - // GZIP (RFC 1952) specifies that strings are NUL-terminated ISO 8859-1 (Latin-1). - if needconv { + // Digest covers the NUL terminator. + z.digest = crc32.Update(z.digest, crc32.IEEETable, z.buf[:i+1]) + + // Strings are ISO 8859-1, Latin-1 (RFC 1952, section 2.3.1). + if needConv { s := make([]rune, 0, i) for _, v := range z.buf[:i] { s = append(s, rune(v)) @@ -155,20 +169,10 @@ func (z *Reader) readString() (string, error) { } } -func (z *Reader) read2() (uint32, error) { - _, err := io.ReadFull(z.r, z.buf[:2]) - if err != nil { - if err == io.EOF { - err = io.ErrUnexpectedEOF - } - return 0, err - } - return uint32(z.buf[0]) | uint32(z.buf[1])<<8, nil -} - -func (z *Reader) readHeader(save bool) error { - _, err := io.ReadFull(z.r, z.buf[:10]) - if err != nil { +// readHeader reads the GZIP header according to section 2.3.1. +// This method does not set z.err. +func (z *Reader) readHeader() (hdr Header, err error) { + if _, err = io.ReadFull(z.r, z.buf[:10]); err != nil { // RFC 1952, section 2.2, says the following: // A gzip file consists of a series of "members" (compressed data sets). // @@ -176,63 +180,52 @@ func (z *Reader) readHeader(save bool) error { // "series" is defined as "one or more" or "zero or more". To err on the // side of caution, Go interprets this to mean "zero or more". // Thus, it is okay to return io.EOF here. - return err + return hdr, err } if z.buf[0] != gzipID1 || z.buf[1] != gzipID2 || z.buf[2] != gzipDeflate { - return ErrHeader + return hdr, ErrHeader } flg := z.buf[3] - if save { - z.ModTime = time.Unix(int64(get4(z.buf[4:8])), 0) - // z.buf[8] is xfl, ignored - z.OS = z.buf[9] - } - z.digest = crc32.Update(0, crc32.IEEETable, z.buf[:10]) + hdr.ModTime = time.Unix(int64(le.Uint32(z.buf[4:8])), 0) + // z.buf[8] is XFL and is currently ignored. + hdr.OS = z.buf[9] + z.digest = crc32.ChecksumIEEE(z.buf[:10]) if flg&flagExtra != 0 { - n, err := z.read2() - if err != nil { - return err + if _, err = io.ReadFull(z.r, z.buf[:2]); err != nil { + return hdr, noEOF(err) } - data := make([]byte, n) + z.digest = crc32.Update(z.digest, crc32.IEEETable, z.buf[:2]) + data := make([]byte, le.Uint16(z.buf[:2])) if _, err = io.ReadFull(z.r, data); err != nil { - if err == io.EOF { - err = io.ErrUnexpectedEOF - } - return err - } - if save { - z.Extra = data + return hdr, noEOF(err) } + z.digest = crc32.Update(z.digest, crc32.IEEETable, data) + hdr.Extra = data } var s string if flg&flagName != 0 { if s, err = z.readString(); err != nil { - return err - } - if save { - z.Name = s + return hdr, err } + hdr.Name = s } if flg&flagComment != 0 { if s, err = z.readString(); err != nil { - return err - } - if save { - z.Comment = s + return hdr, err } + hdr.Comment = s } if flg&flagHdrCrc != 0 { - n, err := z.read2() - if err != nil { - return err + if _, err = io.ReadFull(z.r, z.buf[:2]); err != nil { + return hdr, noEOF(err) } - sum := z.digest & 0xFFFF - if n != sum { - return ErrHeader + digest := le.Uint16(z.buf[:2]) + if digest != uint16(z.digest) { + return hdr, ErrHeader } } @@ -242,7 +235,7 @@ func (z *Reader) readHeader(save bool) error { } else { z.decompressor.(flate.Resetter).Reset(z.r, nil) } - return nil + return hdr, nil } func (z *Reader) Read(p []byte) (n int, err error) { @@ -260,13 +253,11 @@ func (z *Reader) Read(p []byte) (n int, err error) { // Finished file; check checksum and size. if _, err := io.ReadFull(z.r, z.buf[:8]); err != nil { - if err == io.EOF { - err = io.ErrUnexpectedEOF - } - z.err = err - return n, err + z.err = noEOF(err) + return n, z.err } - digest, size := get4(z.buf[:4]), get4(z.buf[4:8]) + digest := le.Uint32(z.buf[:4]) + size := le.Uint32(z.buf[4:8]) if digest != z.digest || size != z.size { z.err = ErrChecksum return n, z.err @@ -279,7 +270,7 @@ func (z *Reader) Read(p []byte) (n int, err error) { } z.err = nil // Remove io.EOF - if z.err = z.readHeader(false); z.err != nil { + if _, z.err = z.readHeader(); z.err != nil { return n, z.err } diff --git a/src/compress/gzip/gunzip_test.go b/src/compress/gzip/gunzip_test.go index e1f79e3db3..fdce91989a 100644 --- a/src/compress/gzip/gunzip_test.go +++ b/src/compress/gzip/gunzip_test.go @@ -292,6 +292,53 @@ var gunzipTests = []gunzipTest{ }, ErrChecksum, }, + { + "f1l3n4m3.tXt", + "header with all fields used", + "", + []byte{ + 0x1f, 0x8b, 0x08, 0x1e, 0x70, 0xf0, 0xf9, 0x4a, + 0x00, 0xaa, 0x09, 0x00, 0x7a, 0x7a, 0x05, 0x00, + 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x31, 0x6c, + 0x33, 0x6e, 0x34, 0x6d, 0x33, 0x2e, 0x74, 0x58, + 0x74, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, + 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, + 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, + 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, + 0x1f, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, + 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, + 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, + 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, + 0x3f, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, + 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, + 0x4f, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, + 0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, + 0x5f, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, + 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, + 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, + 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, + 0x7f, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, + 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, + 0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, + 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, + 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, + 0xa7, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, + 0xaf, 0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, + 0xb7, 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, + 0xbf, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, + 0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, + 0xcf, 0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, + 0xd7, 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, + 0xdf, 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, + 0xe7, 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, + 0xef, 0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, + 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, + 0xff, 0x00, 0x92, 0xfd, 0x01, 0x00, 0x00, 0xff, + 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, + 0x00, + }, + nil, + }, } func TestDecompressor(t *testing.T) { diff --git a/src/compress/gzip/gzip.go b/src/compress/gzip/gzip.go index 4651298585..c702c493c1 100644 --- a/src/compress/gzip/gzip.go +++ b/src/compress/gzip/gzip.go @@ -87,25 +87,12 @@ func (z *Writer) Reset(w io.Writer) { z.init(w, z.level) } -// GZIP (RFC 1952) is little-endian, unlike ZLIB (RFC 1950). -func put2(p []byte, v uint16) { - p[0] = uint8(v >> 0) - p[1] = uint8(v >> 8) -} - -func put4(p []byte, v uint32) { - p[0] = uint8(v >> 0) - p[1] = uint8(v >> 8) - p[2] = uint8(v >> 16) - p[3] = uint8(v >> 24) -} - // writeBytes writes a length-prefixed byte slice to z.w. func (z *Writer) writeBytes(b []byte) error { if len(b) > 0xffff { return errors.New("gzip.Write: Extra data is too large") } - put2(z.buf[:2], uint16(len(b))) + le.PutUint16(z.buf[:2], uint16(len(b))) _, err := z.w.Write(z.buf[:2]) if err != nil { return err @@ -168,7 +155,7 @@ func (z *Writer) Write(p []byte) (int, error) { if z.Comment != "" { z.buf[3] |= 0x10 } - put4(z.buf[4:8], uint32(z.ModTime.Unix())) + le.PutUint32(z.buf[4:8], uint32(z.ModTime.Unix())) if z.level == BestCompression { z.buf[8] = 2 } else if z.level == BestSpeed { @@ -254,8 +241,8 @@ func (z *Writer) Close() error { if z.err != nil { return z.err } - put4(z.buf[:4], z.digest) - put4(z.buf[4:8], z.size) + le.PutUint32(z.buf[:4], z.digest) + le.PutUint32(z.buf[4:8], z.size) _, z.err = z.w.Write(z.buf[:8]) return z.err }