Imported Upstream version 1.4upstream/1.4

5 files changed, 1200 insertions, 0 deletions

diff --git a/src/compress/gzip/gunzip.go b/src/compress/gzip/gunzip.go
new file mode 100644
index 000000000..72ee55c4f
--- /dev/null
+++ b/src/compress/gzip/gunzip.go
@@ -0,0 +1,287 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package gzip implements reading and writing of gzip format compressed files,
+// as specified in RFC 1952.
+package gzip
+
+import (
+	"bufio"
+	"compress/flate"
+	"errors"
+	"hash"
+	"hash/crc32"
+	"io"
+	"time"
+)
+
+const (
+	gzipID1     = 0x1f
+	gzipID2     = 0x8b
+	gzipDeflate = 8
+	flagText    = 1 << 0
+	flagHdrCrc  = 1 << 1
+	flagExtra   = 1 << 2
+	flagName    = 1 << 3
+	flagComment = 1 << 4
+)
+
+func makeReader(r io.Reader) flate.Reader {
+	if rr, ok := r.(flate.Reader); ok {
+		return rr
+	}
+	return bufio.NewReader(r)
+}
+
+var (
+	// ErrChecksum is returned when reading GZIP data that has an invalid checksum.
+	ErrChecksum = errors.New("gzip: invalid checksum")
+	// ErrHeader is returned when reading GZIP data that has an invalid header.
+	ErrHeader = errors.New("gzip: invalid header")
+)
+
+// 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.
+type Header struct {
+	Comment string    // comment
+	Extra   []byte    // "extra data"
+	ModTime time.Time // modification time
+	Name    string    // file name
+	OS      byte      // operating system type
+}
+
+// A Reader is an io.Reader that can be read to retrieve
+// uncompressed data from a gzip-format compressed file.
+//
+// In general, a gzip file can be a concatenation of gzip files,
+// each with its own header.  Reads from the Reader
+// return the concatenation of the uncompressed data of each.
+// Only the first header is recorded in the Reader fields.
+//
+// Gzip files store a length and checksum of the uncompressed data.
+// The Reader will return a ErrChecksum when Read
+// reaches the end of the uncompressed data if it does not
+// have the expected length or checksum.  Clients should treat data
+// returned by Read as tentative until they receive the io.EOF
+// marking the end of the data.
+type Reader struct {
+	Header
+	r            flate.Reader
+	decompressor io.ReadCloser
+	digest       hash.Hash32
+	size         uint32
+	flg          byte
+	buf          [512]byte
+	err          error
+	multistream  bool
+}
+
+// NewReader creates a new Reader reading the given reader.
+// If r does not also implement io.ByteReader,
+// the decompressor may read more data than necessary from r.
+// It is the caller's responsibility to call Close on the Reader when done.
+func NewReader(r io.Reader) (*Reader, error) {
+	z := new(Reader)
+	z.r = makeReader(r)
+	z.multistream = true
+	z.digest = crc32.NewIEEE()
+	if err := z.readHeader(true); err != nil {
+		return nil, err
+	}
+	return z, nil
+}
+
+// Reset discards the Reader z's state and makes it equivalent to the
+// result of its original state from NewReader, but reading from r instead.
+// This permits reusing a Reader rather than allocating a new one.
+func (z *Reader) Reset(r io.Reader) error {
+	z.r = makeReader(r)
+	if z.digest == nil {
+		z.digest = crc32.NewIEEE()
+	} else {
+		z.digest.Reset()
+	}
+	z.size = 0
+	z.err = nil
+	z.multistream = true
+	return z.readHeader(true)
+}
+
+// Multistream controls whether the reader supports multistream files.
+//
+// If enabled (the default), the Reader expects the input to be a sequence
+// of individually gzipped data streams, each with its own header and
+// trailer, ending at EOF. The effect is that the concatenation of a sequence
+// of gzipped files is treated as equivalent to the gzip of the concatenation
+// of the sequence. This is standard behavior for gzip readers.
+//
+// Calling Multistream(false) disables this behavior; disabling the behavior
+// can be useful when reading file formats that distinguish individual gzip
+// data streams or mix gzip data streams with other data streams.
+// In this mode, when the Reader reaches the end of the data stream,
+// Read returns io.EOF. If the underlying reader implements io.ByteReader,
+// it will be left positioned just after the gzip stream.
+// To start the next stream, call z.Reset(r) followed by z.Multistream(false).
+// If there is no next stream, z.Reset(r) will return io.EOF.
+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
+}
+
+func (z *Reader) readString() (string, error) {
+	var err error
+	needconv := false
+	for i := 0; ; i++ {
+		if i >= len(z.buf) {
+			return "", ErrHeader
+		}
+		z.buf[i], err = z.r.ReadByte()
+		if err != nil {
+			return "", err
+		}
+		if z.buf[i] > 0x7f {
+			needconv = true
+		}
+		if z.buf[i] == 0 {
+			// GZIP (RFC 1952) specifies that strings are NUL-terminated ISO 8859-1 (Latin-1).
+			if needconv {
+				s := make([]rune, 0, i)
+				for _, v := range z.buf[0:i] {
+					s = append(s, rune(v))
+				}
+				return string(s), nil
+			}
+			return string(z.buf[0:i]), nil
+		}
+	}
+}
+
+func (z *Reader) read2() (uint32, error) {
+	_, err := io.ReadFull(z.r, z.buf[0:2])
+	if err != nil {
+		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[0:10])
+	if err != nil {
+		return err
+	}
+	if z.buf[0] != gzipID1 || z.buf[1] != gzipID2 || z.buf[2] != gzipDeflate {
+		return ErrHeader
+	}
+	z.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.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 ErrHeader
+		}
+	}
+
+	z.digest.Reset()
+	if z.decompressor == nil {
+		z.decompressor = flate.NewReader(z.r)
+	} else {
+		z.decompressor.(flate.Resetter).Reset(z.r, nil)
+	}
+	return nil
+}
+
+func (z *Reader) Read(p []byte) (n int, err error) {
+	if z.err != nil {
+		return 0, z.err
+	}
+	if len(p) == 0 {
+		return 0, nil
+	}
+
+	n, err = z.decompressor.Read(p)
+	z.digest.Write(p[0:n])
+	z.size += uint32(n)
+	if n != 0 || err != io.EOF {
+		z.err = err
+		return
+	}
+
+	// Finished file; check checksum + size.
+	if _, err := io.ReadFull(z.r, z.buf[0:8]); err != nil {
+		z.err = err
+		return 0, err
+	}
+	crc32, isize := get4(z.buf[0:4]), get4(z.buf[4:8])
+	sum := z.digest.Sum32()
+	if sum != crc32 || isize != z.size {
+		z.err = ErrChecksum
+		return 0, z.err
+	}
+
+	// File is ok; is there another?
+	if !z.multistream {
+		return 0, io.EOF
+	}
+
+	if err = z.readHeader(false); err != nil {
+		z.err = err
+		return
+	}
+
+	// Yes.  Reset and read from it.
+	z.digest.Reset()
+	z.size = 0
+	return z.Read(p)
+}
+
+// Close closes the Reader. It does not close the underlying io.Reader.
+func (z *Reader) Close() error { return z.decompressor.Close() }
diff --git a/src/compress/gzip/gunzip_test.go b/src/compress/gzip/gunzip_test.go
new file mode 100644
index 000000000..0636dec9a
--- /dev/null
+++ b/src/compress/gzip/gunzip_test.go
@@ -0,0 +1,410 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gzip
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"os"
+	"strings"
+	"testing"
+	"time"
+)
+
+type gunzipTest struct {
+	name string
+	desc string
+	raw  string
+	gzip []byte
+	err  error
+}
+
+var gunzipTests = []gunzipTest{
+	{ // has 1 empty fixed-huffman block
+		"empty.txt",
+		"empty.txt",
+		"",
+		[]byte{
+			0x1f, 0x8b, 0x08, 0x08, 0xf7, 0x5e, 0x14, 0x4a,
+			0x00, 0x03, 0x65, 0x6d, 0x70, 0x74, 0x79, 0x2e,
+			0x74, 0x78, 0x74, 0x00, 0x03, 0x00, 0x00, 0x00,
+			0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		},
+		nil,
+	},
+	{ // has 1 non-empty fixed huffman block
+		"hello.txt",
+		"hello.txt",
+		"hello world\n",
+		[]byte{
+			0x1f, 0x8b, 0x08, 0x08, 0xc8, 0x58, 0x13, 0x4a,
+			0x00, 0x03, 0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x2e,
+			0x74, 0x78, 0x74, 0x00, 0xcb, 0x48, 0xcd, 0xc9,
+			0xc9, 0x57, 0x28, 0xcf, 0x2f, 0xca, 0x49, 0xe1,
+			0x02, 0x00, 0x2d, 0x3b, 0x08, 0xaf, 0x0c, 0x00,
+			0x00, 0x00,
+		},
+		nil,
+	},
+	{ // concatenation
+		"hello.txt",
+		"hello.txt x2",
+		"hello world\n" +
+			"hello world\n",
+		[]byte{
+			0x1f, 0x8b, 0x08, 0x08, 0xc8, 0x58, 0x13, 0x4a,
+			0x00, 0x03, 0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x2e,
+			0x74, 0x78, 0x74, 0x00, 0xcb, 0x48, 0xcd, 0xc9,
+			0xc9, 0x57, 0x28, 0xcf, 0x2f, 0xca, 0x49, 0xe1,
+			0x02, 0x00, 0x2d, 0x3b, 0x08, 0xaf, 0x0c, 0x00,
+			0x00, 0x00,
+			0x1f, 0x8b, 0x08, 0x08, 0xc8, 0x58, 0x13, 0x4a,
+			0x00, 0x03, 0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x2e,
+			0x74, 0x78, 0x74, 0x00, 0xcb, 0x48, 0xcd, 0xc9,
+			0xc9, 0x57, 0x28, 0xcf, 0x2f, 0xca, 0x49, 0xe1,
+			0x02, 0x00, 0x2d, 0x3b, 0x08, 0xaf, 0x0c, 0x00,
+			0x00, 0x00,
+		},
+		nil,
+	},
+	{ // has a fixed huffman block with some length-distance pairs
+		"shesells.txt",
+		"shesells.txt",
+		"she sells seashells by the seashore\n",
+		[]byte{
+			0x1f, 0x8b, 0x08, 0x08, 0x72, 0x66, 0x8b, 0x4a,
+			0x00, 0x03, 0x73, 0x68, 0x65, 0x73, 0x65, 0x6c,
+			0x6c, 0x73, 0x2e, 0x74, 0x78, 0x74, 0x00, 0x2b,
+			0xce, 0x48, 0x55, 0x28, 0x4e, 0xcd, 0xc9, 0x29,
+			0x06, 0x92, 0x89, 0xc5, 0x19, 0x60, 0x56, 0x52,
+			0xa5, 0x42, 0x09, 0x58, 0x18, 0x28, 0x90, 0x5f,
+			0x94, 0xca, 0x05, 0x00, 0x76, 0xb0, 0x3b, 0xeb,
+			0x24, 0x00, 0x00, 0x00,
+		},
+		nil,
+	},
+	{ // has dynamic huffman blocks
+		"gettysburg",
+		"gettysburg",
+		"  Four score and seven years ago our fathers brought forth on\n" +
+			"this continent, a new nation, conceived in Liberty, and dedicated\n" +
+			"to the proposition that all men are created equal.\n" +
+			"  Now we are engaged in a great Civil War, testing whether that\n" +
+			"nation, or any nation so conceived and so dedicated, can long\n" +
+			"endure.\n" +
+			"  We are met on a great battle-field of that war.\n" +
+			"  We have come to dedicate a portion of that field, as a final\n" +
+			"resting place for those who here gave their lives that that\n" +
+			"nation might live.  It is altogether fitting and proper that\n" +
+			"we should do this.\n" +
+			"  But, in a larger sense, we can not dedicate — we can not\n" +
+			"consecrate — we can not hallow — this ground.\n" +
+			"  The brave men, living and dead, who struggled here, have\n" +
+			"consecrated it, far above our poor power to add or detract.\n" +
+			"The world will little note, nor long remember what we say here,\n" +
+			"but it can never forget what they did here.\n" +
+			"  It is for us the living, rather, to be dedicated here to the\n" +
+			"unfinished work which they who fought here have thus far so\n" +
+			"nobly advanced.  It is rather for us to be here dedicated to\n" +
+			"the great task remaining before us — that from these honored\n" +
+			"dead we take increased devotion to that cause for which they\n" +
+			"gave the last full measure of devotion —\n" +
+			"  that we here highly resolve that these dead shall not have\n" +
+			"died in vain — that this nation, under God, shall have a new\n" +
+			"birth of freedom — and that government of the people, by the\n" +
+			"people, for the people, shall not perish from this earth.\n" +
+			"\n" +
+			"Abraham Lincoln, November 19, 1863, Gettysburg, Pennsylvania\n",
+		[]byte{
+			0x1f, 0x8b, 0x08, 0x08, 0xd1, 0x12, 0x2b, 0x4a,
+			0x00, 0x03, 0x67, 0x65, 0x74, 0x74, 0x79, 0x73,
+			0x62, 0x75, 0x72, 0x67, 0x00, 0x65, 0x54, 0xcd,
+			0x6e, 0xd4, 0x30, 0x10, 0xbe, 0xfb, 0x29, 0xe6,
+			0x01, 0x42, 0xa5, 0x0a, 0x09, 0xc1, 0x11, 0x90,
+			0x40, 0x48, 0xa8, 0xe2, 0x80, 0xd4, 0xf3, 0x24,
+			0x9e, 0x24, 0x56, 0xbd, 0x9e, 0xc5, 0x76, 0x76,
+			0x95, 0x1b, 0x0f, 0xc1, 0x13, 0xf2, 0x24, 0x7c,
+			0x63, 0x77, 0x9b, 0x4a, 0x5c, 0xaa, 0x6e, 0x6c,
+			0xcf, 0x7c, 0x7f, 0x33, 0x44, 0x5f, 0x74, 0xcb,
+			0x54, 0x26, 0xcd, 0x42, 0x9c, 0x3c, 0x15, 0xb9,
+			0x48, 0xa2, 0x5d, 0x38, 0x17, 0xe2, 0x45, 0xc9,
+			0x4e, 0x67, 0xae, 0xab, 0xe0, 0xf7, 0x98, 0x75,
+			0x5b, 0xd6, 0x4a, 0xb3, 0xe6, 0xba, 0x92, 0x26,
+			0x57, 0xd7, 0x50, 0x68, 0xd2, 0x54, 0x43, 0x92,
+			0x54, 0x07, 0x62, 0x4a, 0x72, 0xa5, 0xc4, 0x35,
+			0x68, 0x1a, 0xec, 0x60, 0x92, 0x70, 0x11, 0x4f,
+			0x21, 0xd1, 0xf7, 0x30, 0x4a, 0xae, 0xfb, 0xd0,
+			0x9a, 0x78, 0xf1, 0x61, 0xe2, 0x2a, 0xde, 0x55,
+			0x25, 0xd4, 0xa6, 0x73, 0xd6, 0xb3, 0x96, 0x60,
+			0xef, 0xf0, 0x9b, 0x2b, 0x71, 0x8c, 0x74, 0x02,
+			0x10, 0x06, 0xac, 0x29, 0x8b, 0xdd, 0x25, 0xf9,
+			0xb5, 0x71, 0xbc, 0x73, 0x44, 0x0f, 0x7a, 0xa5,
+			0xab, 0xb4, 0x33, 0x49, 0x0b, 0x2f, 0xbd, 0x03,
+			0xd3, 0x62, 0x17, 0xe9, 0x73, 0xb8, 0x84, 0x48,
+			0x8f, 0x9c, 0x07, 0xaa, 0x52, 0x00, 0x6d, 0xa1,
+			0xeb, 0x2a, 0xc6, 0xa0, 0x95, 0x76, 0x37, 0x78,
+			0x9a, 0x81, 0x65, 0x7f, 0x46, 0x4b, 0x45, 0x5f,
+			0xe1, 0x6d, 0x42, 0xe8, 0x01, 0x13, 0x5c, 0x38,
+			0x51, 0xd4, 0xb4, 0x38, 0x49, 0x7e, 0xcb, 0x62,
+			0x28, 0x1e, 0x3b, 0x82, 0x93, 0x54, 0x48, 0xf1,
+			0xd2, 0x7d, 0xe4, 0x5a, 0xa3, 0xbc, 0x99, 0x83,
+			0x44, 0x4f, 0x3a, 0x77, 0x36, 0x57, 0xce, 0xcf,
+			0x2f, 0x56, 0xbe, 0x80, 0x90, 0x9e, 0x84, 0xea,
+			0x51, 0x1f, 0x8f, 0xcf, 0x90, 0xd4, 0x60, 0xdc,
+			0x5e, 0xb4, 0xf7, 0x10, 0x0b, 0x26, 0xe0, 0xff,
+			0xc4, 0xd1, 0xe5, 0x67, 0x2e, 0xe7, 0xc8, 0x93,
+			0x98, 0x05, 0xb8, 0xa8, 0x45, 0xc0, 0x4d, 0x09,
+			0xdc, 0x84, 0x16, 0x2b, 0x0d, 0x9a, 0x21, 0x53,
+			0x04, 0x8b, 0xd2, 0x0b, 0xbd, 0xa2, 0x4c, 0xa7,
+			0x60, 0xee, 0xd9, 0xe1, 0x1d, 0xd1, 0xb7, 0x4a,
+			0x30, 0x8f, 0x63, 0xd5, 0xa5, 0x8b, 0x33, 0x87,
+			0xda, 0x1a, 0x18, 0x79, 0xf3, 0xe3, 0xa6, 0x17,
+			0x94, 0x2e, 0xab, 0x6e, 0xa0, 0xe3, 0xcd, 0xac,
+			0x50, 0x8c, 0xca, 0xa7, 0x0d, 0x76, 0x37, 0xd1,
+			0x23, 0xe7, 0x05, 0x57, 0x8b, 0xa4, 0x22, 0x83,
+			0xd9, 0x62, 0x52, 0x25, 0xad, 0x07, 0xbb, 0xbf,
+			0xbf, 0xff, 0xbc, 0xfa, 0xee, 0x20, 0x73, 0x91,
+			0x29, 0xff, 0x7f, 0x02, 0x71, 0x62, 0x84, 0xb5,
+			0xf6, 0xb5, 0x25, 0x6b, 0x41, 0xde, 0x92, 0xb7,
+			0x76, 0x3f, 0x91, 0x91, 0x31, 0x1b, 0x41, 0x84,
+			0x62, 0x30, 0x0a, 0x37, 0xa4, 0x5e, 0x18, 0x3a,
+			0x99, 0x08, 0xa5, 0xe6, 0x6d, 0x59, 0x22, 0xec,
+			0x33, 0x39, 0x86, 0x26, 0xf5, 0xab, 0x66, 0xc8,
+			0x08, 0x20, 0xcf, 0x0c, 0xd7, 0x47, 0x45, 0x21,
+			0x0b, 0xf6, 0x59, 0xd5, 0xfe, 0x5c, 0x8d, 0xaa,
+			0x12, 0x7b, 0x6f, 0xa1, 0xf0, 0x52, 0x33, 0x4f,
+			0xf5, 0xce, 0x59, 0xd3, 0xab, 0x66, 0x10, 0xbf,
+			0x06, 0xc4, 0x31, 0x06, 0x73, 0xd6, 0x80, 0xa2,
+			0x78, 0xc2, 0x45, 0xcb, 0x03, 0x65, 0x39, 0xc9,
+			0x09, 0xd1, 0x06, 0x04, 0x33, 0x1a, 0x5a, 0xf1,
+			0xde, 0x01, 0xb8, 0x71, 0x83, 0xc4, 0xb5, 0xb3,
+			0xc3, 0x54, 0x65, 0x33, 0x0d, 0x5a, 0xf7, 0x9b,
+			0x90, 0x7c, 0x27, 0x1f, 0x3a, 0x58, 0xa3, 0xd8,
+			0xfd, 0x30, 0x5f, 0xb7, 0xd2, 0x66, 0xa2, 0x93,
+			0x1c, 0x28, 0xb7, 0xe9, 0x1b, 0x0c, 0xe1, 0x28,
+			0x47, 0x26, 0xbb, 0xe9, 0x7d, 0x7e, 0xdc, 0x96,
+			0x10, 0x92, 0x50, 0x56, 0x7c, 0x06, 0xe2, 0x27,
+			0xb4, 0x08, 0xd3, 0xda, 0x7b, 0x98, 0x34, 0x73,
+			0x9f, 0xdb, 0xf6, 0x62, 0xed, 0x31, 0x41, 0x13,
+			0xd3, 0xa2, 0xa8, 0x4b, 0x3a, 0xc6, 0x1d, 0xe4,
+			0x2f, 0x8c, 0xf8, 0xfb, 0x97, 0x64, 0xf4, 0xb6,
+			0x2f, 0x80, 0x5a, 0xf3, 0x56, 0xe0, 0x40, 0x50,
+			0xd5, 0x19, 0xd0, 0x1e, 0xfc, 0xca, 0xe5, 0xc9,
+			0xd4, 0x60, 0x00, 0x81, 0x2e, 0xa3, 0xcc, 0xb6,
+			0x52, 0xf0, 0xb4, 0xdb, 0x69, 0x99, 0xce, 0x7a,
+			0x32, 0x4c, 0x08, 0xed, 0xaa, 0x10, 0x10, 0xe3,
+			0x6f, 0xee, 0x99, 0x68, 0x95, 0x9f, 0x04, 0x71,
+			0xb2, 0x49, 0x2f, 0x62, 0xa6, 0x5e, 0xb4, 0xef,
+			0x02, 0xed, 0x4f, 0x27, 0xde, 0x4a, 0x0f, 0xfd,
+			0xc1, 0xcc, 0xdd, 0x02, 0x8f, 0x08, 0x16, 0x54,
+			0xdf, 0xda, 0xca, 0xe0, 0x82, 0xf1, 0xb4, 0x31,
+			0x7a, 0xa9, 0x81, 0xfe, 0x90, 0xb7, 0x3e, 0xdb,
+			0xd3, 0x35, 0xc0, 0x20, 0x80, 0x33, 0x46, 0x4a,
+			0x63, 0xab, 0xd1, 0x0d, 0x29, 0xd2, 0xe2, 0x84,
+			0xb8, 0xdb, 0xfa, 0xe9, 0x89, 0x44, 0x86, 0x7c,
+			0xe8, 0x0b, 0xe6, 0x02, 0x6a, 0x07, 0x9b, 0x96,
+			0xd0, 0xdb, 0x2e, 0x41, 0x4c, 0xa1, 0xd5, 0x57,
+			0x45, 0x14, 0xfb, 0xe3, 0xa6, 0x72, 0x5b, 0x87,
+			0x6e, 0x0c, 0x6d, 0x5b, 0xce, 0xe0, 0x2f, 0xe2,
+			0x21, 0x81, 0x95, 0xb0, 0xe8, 0xb6, 0x32, 0x0b,
+			0xb2, 0x98, 0x13, 0x52, 0x5d, 0xfb, 0xec, 0x63,
+			0x17, 0x8a, 0x9e, 0x23, 0x22, 0x36, 0xee, 0xcd,
+			0xda, 0xdb, 0xcf, 0x3e, 0xf1, 0xc7, 0xf1, 0x01,
+			0x12, 0x93, 0x0a, 0xeb, 0x6f, 0xf2, 0x02, 0x15,
+			0x96, 0x77, 0x5d, 0xef, 0x9c, 0xfb, 0x88, 0x91,
+			0x59, 0xf9, 0x84, 0xdd, 0x9b, 0x26, 0x8d, 0x80,
+			0xf9, 0x80, 0x66, 0x2d, 0xac, 0xf7, 0x1f, 0x06,
+			0xba, 0x7f, 0xff, 0xee, 0xed, 0x40, 0x5f, 0xa5,
+			0xd6, 0xbd, 0x8c, 0x5b, 0x46, 0xd2, 0x7e, 0x48,
+			0x4a, 0x65, 0x8f, 0x08, 0x42, 0x60, 0xf7, 0x0f,
+			0xb9, 0x16, 0x0b, 0x0c, 0x1a, 0x06, 0x00, 0x00,
+		},
+		nil,
+	},
+	{ // has 1 non-empty fixed huffman block then garbage
+		"hello.txt",
+		"hello.txt + garbage",
+		"hello world\n",
+		[]byte{
+			0x1f, 0x8b, 0x08, 0x08, 0xc8, 0x58, 0x13, 0x4a,
+			0x00, 0x03, 0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x2e,
+			0x74, 0x78, 0x74, 0x00, 0xcb, 0x48, 0xcd, 0xc9,
+			0xc9, 0x57, 0x28, 0xcf, 0x2f, 0xca, 0x49, 0xe1,
+			0x02, 0x00, 0x2d, 0x3b, 0x08, 0xaf, 0x0c, 0x00,
+			0x00, 0x00, 'g', 'a', 'r', 'b', 'a', 'g', 'e', '!', '!', '!',
+		},
+		ErrHeader,
+	},
+	{ // has 1 non-empty fixed huffman block not enough header
+		"hello.txt",
+		"hello.txt + garbage",
+		"hello world\n",
+		[]byte{
+			0x1f, 0x8b, 0x08, 0x08, 0xc8, 0x58, 0x13, 0x4a,
+			0x00, 0x03, 0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x2e,
+			0x74, 0x78, 0x74, 0x00, 0xcb, 0x48, 0xcd, 0xc9,
+			0xc9, 0x57, 0x28, 0xcf, 0x2f, 0xca, 0x49, 0xe1,
+			0x02, 0x00, 0x2d, 0x3b, 0x08, 0xaf, 0x0c, 0x00,
+			0x00, 0x00, gzipID1,
+		},
+		io.ErrUnexpectedEOF,
+	},
+	{ // has 1 non-empty fixed huffman block but corrupt checksum
+		"hello.txt",
+		"hello.txt + corrupt checksum",
+		"hello world\n",
+		[]byte{
+			0x1f, 0x8b, 0x08, 0x08, 0xc8, 0x58, 0x13, 0x4a,
+			0x00, 0x03, 0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x2e,
+			0x74, 0x78, 0x74, 0x00, 0xcb, 0x48, 0xcd, 0xc9,
+			0xc9, 0x57, 0x28, 0xcf, 0x2f, 0xca, 0x49, 0xe1,
+			0x02, 0x00, 0xff, 0xff, 0xff, 0xff, 0x0c, 0x00,
+			0x00, 0x00,
+		},
+		ErrChecksum,
+	},
+	{ // has 1 non-empty fixed huffman block but corrupt size
+		"hello.txt",
+		"hello.txt + corrupt size",
+		"hello world\n",
+		[]byte{
+			0x1f, 0x8b, 0x08, 0x08, 0xc8, 0x58, 0x13, 0x4a,
+			0x00, 0x03, 0x68, 0x65, 0x6c, 0x6c, 0x6f, 0x2e,
+			0x74, 0x78, 0x74, 0x00, 0xcb, 0x48, 0xcd, 0xc9,
+			0xc9, 0x57, 0x28, 0xcf, 0x2f, 0xca, 0x49, 0xe1,
+			0x02, 0x00, 0x2d, 0x3b, 0x08, 0xaf, 0xff, 0x00,
+			0x00, 0x00,
+		},
+		ErrChecksum,
+	},
+}
+
+func TestDecompressor(t *testing.T) {
+	b := new(bytes.Buffer)
+	for _, tt := range gunzipTests {
+		in := bytes.NewReader(tt.gzip)
+		gzip, err := NewReader(in)
+		if err != nil {
+			t.Errorf("%s: NewReader: %s", tt.name, err)
+			continue
+		}
+		defer gzip.Close()
+		if tt.name != gzip.Name {
+			t.Errorf("%s: got name %s", tt.name, gzip.Name)
+		}
+		b.Reset()
+		n, err := io.Copy(b, gzip)
+		if err != tt.err {
+			t.Errorf("%s: io.Copy: %v want %v", tt.name, err, tt.err)
+		}
+		s := b.String()
+		if s != tt.raw {
+			t.Errorf("%s: got %d-byte %q want %d-byte %q", tt.name, n, s, len(tt.raw), tt.raw)
+		}
+
+		// Test Reader Reset.
+		in = bytes.NewReader(tt.gzip)
+		err = gzip.Reset(in)
+		if err != nil {
+			t.Errorf("%s: Reset: %s", tt.name, err)
+			continue
+		}
+		if tt.name != gzip.Name {
+			t.Errorf("%s: got name %s", tt.name, gzip.Name)
+		}
+		b.Reset()
+		n, err = io.Copy(b, gzip)
+		if err != tt.err {
+			t.Errorf("%s: io.Copy: %v want %v", tt.name, err, tt.err)
+		}
+		s = b.String()
+		if s != tt.raw {
+			t.Errorf("%s: got %d-byte %q want %d-byte %q", tt.name, n, s, len(tt.raw), tt.raw)
+		}
+	}
+}
+
+func TestIssue6550(t *testing.T) {
+	f, err := os.Open("testdata/issue6550.gz")
+	if err != nil {
+		t.Fatal(err)
+	}
+	gzip, err := NewReader(f)
+	if err != nil {
+		t.Fatalf("NewReader(testdata/issue6550.gz): %v", err)
+	}
+	defer gzip.Close()
+	done := make(chan bool, 1)
+	go func() {
+		_, err := io.Copy(ioutil.Discard, gzip)
+		if err == nil {
+			t.Errorf("Copy succeeded")
+		} else {
+			t.Logf("Copy failed (correctly): %v", err)
+		}
+		done <- true
+	}()
+	select {
+	case <-time.After(1 * time.Second):
+		t.Errorf("Copy hung")
+	case <-done:
+		// ok
+	}
+}
+
+func TestInitialReset(t *testing.T) {
+	var r Reader
+	if err := r.Reset(bytes.NewReader(gunzipTests[1].gzip)); err != nil {
+		t.Error(err)
+	}
+	var buf bytes.Buffer
+	if _, err := io.Copy(&buf, &r); err != nil {
+		t.Error(err)
+	}
+	if s := buf.String(); s != gunzipTests[1].raw {
+		t.Errorf("got %q want %q", s, gunzipTests[1].raw)
+	}
+}
+
+func TestMultistreamFalse(t *testing.T) {
+	// Find concatenation test.
+	var tt gunzipTest
+	for _, tt = range gunzipTests {
+		if strings.HasSuffix(tt.desc, " x2") {
+			goto Found
+		}
+	}
+	t.Fatal("cannot find hello.txt x2 in gunzip tests")
+
+Found:
+	br := bytes.NewReader(tt.gzip)
+	var r Reader
+	if err := r.Reset(br); err != nil {
+		t.Fatalf("first reset: %v", err)
+	}
+
+	// Expect two streams with "hello world\n", then real EOF.
+	const hello = "hello world\n"
+
+	r.Multistream(false)
+	data, err := ioutil.ReadAll(&r)
+	if string(data) != hello || err != nil {
+		t.Fatalf("first stream = %q, %v, want %q, %v", string(data), err, hello, nil)
+	}
+
+	if err := r.Reset(br); err != nil {
+		t.Fatalf("second reset: %v", err)
+	}
+	r.Multistream(false)
+	data, err = ioutil.ReadAll(&r)
+	if string(data) != hello || err != nil {
+		t.Fatalf("second stream = %q, %v, want %q, %v", string(data), err, hello, nil)
+	}
+
+	if err := r.Reset(br); err != io.EOF {
+		t.Fatalf("third reset: err=%v, want io.EOF", err)
+	}
+}
diff --git a/src/compress/gzip/gzip.go b/src/compress/gzip/gzip.go
new file mode 100644
index 000000000..5131d128e
--- /dev/null
+++ b/src/compress/gzip/gzip.go
@@ -0,0 +1,272 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gzip
+
+import (
+	"compress/flate"
+	"errors"
+	"fmt"
+	"hash"
+	"hash/crc32"
+	"io"
+)
+
+// These constants are copied from the flate package, so that code that imports
+// "compress/gzip" does not also have to import "compress/flate".
+const (
+	NoCompression      = flate.NoCompression
+	BestSpeed          = flate.BestSpeed
+	BestCompression    = flate.BestCompression
+	DefaultCompression = flate.DefaultCompression
+)
+
+// A Writer is an io.WriteCloser.
+// Writes to a Writer are compressed and written to w.
+type Writer struct {
+	Header
+	w           io.Writer
+	level       int
+	wroteHeader bool
+	compressor  *flate.Writer
+	digest      hash.Hash32
+	size        uint32
+	closed      bool
+	buf         [10]byte
+	err         error
+}
+
+// NewWriter returns a new Writer.
+// Writes to the returned writer are compressed and written to w.
+//
+// It is the caller's responsibility to call Close on the WriteCloser when done.
+// Writes may be buffered and not flushed until Close.
+//
+// Callers that wish to set the fields in Writer.Header must do so before
+// the first call to Write or Close. The Comment and Name header fields are
+// UTF-8 strings in Go, but the underlying format requires NUL-terminated ISO
+// 8859-1 (Latin-1). NUL or non-Latin-1 runes in those strings will lead to an
+// error on Write.
+func NewWriter(w io.Writer) *Writer {
+	z, _ := NewWriterLevel(w, DefaultCompression)
+	return z
+}
+
+// NewWriterLevel is like NewWriter but specifies the compression level instead
+// of assuming DefaultCompression.
+//
+// The compression level can be DefaultCompression, NoCompression, or any
+// integer value between BestSpeed and BestCompression inclusive. The error
+// returned will be nil if the level is valid.
+func NewWriterLevel(w io.Writer, level int) (*Writer, error) {
+	if level < DefaultCompression || level > BestCompression {
+		return nil, fmt.Errorf("gzip: invalid compression level: %d", level)
+	}
+	z := new(Writer)
+	z.init(w, level)
+	return z, nil
+}
+
+func (z *Writer) init(w io.Writer, level int) {
+	digest := z.digest
+	if digest != nil {
+		digest.Reset()
+	} else {
+		digest = crc32.NewIEEE()
+	}
+	compressor := z.compressor
+	if compressor != nil {
+		compressor.Reset(w)
+	}
+	*z = Writer{
+		Header: Header{
+			OS: 255, // unknown
+		},
+		w:          w,
+		level:      level,
+		digest:     digest,
+		compressor: compressor,
+	}
+}
+
+// Reset discards the Writer z's state and makes it equivalent to the
+// result of its original state from NewWriter or NewWriterLevel, but
+// writing to w instead. This permits reusing a Writer rather than
+// allocating a new one.
+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[0:2], uint16(len(b)))
+	_, err := z.w.Write(z.buf[0:2])
+	if err != nil {
+		return err
+	}
+	_, err = z.w.Write(b)
+	return err
+}
+
+// writeString writes a UTF-8 string s in GZIP's format to z.w.
+// GZIP (RFC 1952) specifies that strings are NUL-terminated ISO 8859-1 (Latin-1).
+func (z *Writer) writeString(s string) (err error) {
+	// GZIP stores Latin-1 strings; error if non-Latin-1; convert if non-ASCII.
+	needconv := false
+	for _, v := range s {
+		if v == 0 || v > 0xff {
+			return errors.New("gzip.Write: non-Latin-1 header string")
+		}
+		if v > 0x7f {
+			needconv = true
+		}
+	}
+	if needconv {
+		b := make([]byte, 0, len(s))
+		for _, v := range s {
+			b = append(b, byte(v))
+		}
+		_, err = z.w.Write(b)
+	} else {
+		_, err = io.WriteString(z.w, s)
+	}
+	if err != nil {
+		return err
+	}
+	// GZIP strings are NUL-terminated.
+	z.buf[0] = 0
+	_, err = z.w.Write(z.buf[0:1])
+	return err
+}
+
+// Write writes a compressed form of p to the underlying io.Writer. The
+// compressed bytes are not necessarily flushed until the Writer is closed.
+func (z *Writer) Write(p []byte) (int, error) {
+	if z.err != nil {
+		return 0, z.err
+	}
+	var n int
+	// Write the GZIP header lazily.
+	if !z.wroteHeader {
+		z.wroteHeader = true
+		z.buf[0] = gzipID1
+		z.buf[1] = gzipID2
+		z.buf[2] = gzipDeflate
+		z.buf[3] = 0
+		if z.Extra != nil {
+			z.buf[3] |= 0x04
+		}
+		if z.Name != "" {
+			z.buf[3] |= 0x08
+		}
+		if z.Comment != "" {
+			z.buf[3] |= 0x10
+		}
+		put4(z.buf[4:8], uint32(z.ModTime.Unix()))
+		if z.level == BestCompression {
+			z.buf[8] = 2
+		} else if z.level == BestSpeed {
+			z.buf[8] = 4
+		} else {
+			z.buf[8] = 0
+		}
+		z.buf[9] = z.OS
+		n, z.err = z.w.Write(z.buf[0:10])
+		if z.err != nil {
+			return n, z.err
+		}
+		if z.Extra != nil {
+			z.err = z.writeBytes(z.Extra)
+			if z.err != nil {
+				return n, z.err
+			}
+		}
+		if z.Name != "" {
+			z.err = z.writeString(z.Name)
+			if z.err != nil {
+				return n, z.err
+			}
+		}
+		if z.Comment != "" {
+			z.err = z.writeString(z.Comment)
+			if z.err != nil {
+				return n, z.err
+			}
+		}
+		if z.compressor == nil {
+			z.compressor, _ = flate.NewWriter(z.w, z.level)
+		}
+	}
+	z.size += uint32(len(p))
+	z.digest.Write(p)
+	n, z.err = z.compressor.Write(p)
+	return n, z.err
+}
+
+// Flush flushes any pending compressed data to the underlying writer.
+//
+// It is useful mainly in compressed network protocols, to ensure that
+// a remote reader has enough data to reconstruct a packet. Flush does
+// not return until the data has been written. If the underlying
+// writer returns an error, Flush returns that error.
+//
+// In the terminology of the zlib library, Flush is equivalent to Z_SYNC_FLUSH.
+func (z *Writer) Flush() error {
+	if z.err != nil {
+		return z.err
+	}
+	if z.closed {
+		return nil
+	}
+	if !z.wroteHeader {
+		z.Write(nil)
+		if z.err != nil {
+			return z.err
+		}
+	}
+	z.err = z.compressor.Flush()
+	return z.err
+}
+
+// Close closes the Writer, flushing any unwritten data to the underlying
+// io.Writer, but does not close the underlying io.Writer.
+func (z *Writer) Close() error {
+	if z.err != nil {
+		return z.err
+	}
+	if z.closed {
+		return nil
+	}
+	z.closed = true
+	if !z.wroteHeader {
+		z.Write(nil)
+		if z.err != nil {
+			return z.err
+		}
+	}
+	z.err = z.compressor.Close()
+	if z.err != nil {
+		return z.err
+	}
+	put4(z.buf[0:4], z.digest.Sum32())
+	put4(z.buf[4:8], z.size)
+	_, z.err = z.w.Write(z.buf[0:8])
+	return z.err
+}
diff --git a/src/compress/gzip/gzip_test.go b/src/compress/gzip/gzip_test.go
new file mode 100644
index 000000000..09271b24e
--- /dev/null
+++ b/src/compress/gzip/gzip_test.go
@@ -0,0 +1,231 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package gzip
+
+import (
+	"bufio"
+	"bytes"
+	"io/ioutil"
+	"testing"
+	"time"
+)
+
+// TestEmpty tests that an empty payload still forms a valid GZIP stream.
+func TestEmpty(t *testing.T) {
+	buf := new(bytes.Buffer)
+
+	if err := NewWriter(buf).Close(); err != nil {
+		t.Fatalf("Writer.Close: %v", err)
+	}
+
+	r, err := NewReader(buf)
+	if err != nil {
+		t.Fatalf("NewReader: %v", err)
+	}
+	b, err := ioutil.ReadAll(r)
+	if err != nil {
+		t.Fatalf("ReadAll: %v", err)
+	}
+	if len(b) != 0 {
+		t.Fatalf("got %d bytes, want 0", len(b))
+	}
+	if err := r.Close(); err != nil {
+		t.Fatalf("Reader.Close: %v", err)
+	}
+}
+
+// TestRoundTrip tests that gzipping and then gunzipping is the identity
+// function.
+func TestRoundTrip(t *testing.T) {
+	buf := new(bytes.Buffer)
+
+	w := NewWriter(buf)
+	w.Comment = "comment"
+	w.Extra = []byte("extra")
+	w.ModTime = time.Unix(1e8, 0)
+	w.Name = "name"
+	if _, err := w.Write([]byte("payload")); err != nil {
+		t.Fatalf("Write: %v", err)
+	}
+	if err := w.Close(); err != nil {
+		t.Fatalf("Writer.Close: %v", err)
+	}
+
+	r, err := NewReader(buf)
+	if err != nil {
+		t.Fatalf("NewReader: %v", err)
+	}
+	b, err := ioutil.ReadAll(r)
+	if err != nil {
+		t.Fatalf("ReadAll: %v", err)
+	}
+	if string(b) != "payload" {
+		t.Fatalf("payload is %q, want %q", string(b), "payload")
+	}
+	if r.Comment != "comment" {
+		t.Fatalf("comment is %q, want %q", r.Comment, "comment")
+	}
+	if string(r.Extra) != "extra" {
+		t.Fatalf("extra is %q, want %q", r.Extra, "extra")
+	}
+	if r.ModTime.Unix() != 1e8 {
+		t.Fatalf("mtime is %d, want %d", r.ModTime.Unix(), uint32(1e8))
+	}
+	if r.Name != "name" {
+		t.Fatalf("name is %q, want %q", r.Name, "name")
+	}
+	if err := r.Close(); err != nil {
+		t.Fatalf("Reader.Close: %v", err)
+	}
+}
+
+// TestLatin1 tests the internal functions for converting to and from Latin-1.
+func TestLatin1(t *testing.T) {
+	latin1 := []byte{0xc4, 'u', 0xdf, 'e', 'r', 'u', 'n', 'g', 0}
+	utf8 := "Äußerung"
+	z := Reader{r: bufio.NewReader(bytes.NewReader(latin1))}
+	s, err := z.readString()
+	if err != nil {
+		t.Fatalf("readString: %v", err)
+	}
+	if s != utf8 {
+		t.Fatalf("read latin-1: got %q, want %q", s, utf8)
+	}
+
+	buf := bytes.NewBuffer(make([]byte, 0, len(latin1)))
+	c := Writer{w: buf}
+	if err = c.writeString(utf8); err != nil {
+		t.Fatalf("writeString: %v", err)
+	}
+	s = buf.String()
+	if s != string(latin1) {
+		t.Fatalf("write utf-8: got %q, want %q", s, string(latin1))
+	}
+}
+
+// TestLatin1RoundTrip tests that metadata that is representable in Latin-1
+// survives a round trip.
+func TestLatin1RoundTrip(t *testing.T) {
+	testCases := []struct {
+		name string
+		ok   bool
+	}{
+		{"", true},
+		{"ASCII is OK", true},
+		{"unless it contains a NUL\x00", false},
+		{"no matter where \x00 occurs", false},
+		{"\x00\x00\x00", false},
+		{"Látin-1 also passes (U+00E1)", true},
+		{"but LĀtin Extended-A (U+0100) does not", false},
+		{"neither does 日本語", false},
+		{"invalid UTF-8 also \xffails", false},
+		{"\x00 as does Látin-1 with NUL", false},
+	}
+	for _, tc := range testCases {
+		buf := new(bytes.Buffer)
+
+		w := NewWriter(buf)
+		w.Name = tc.name
+		err := w.Close()
+		if (err == nil) != tc.ok {
+			t.Errorf("Writer.Close: name = %q, err = %v", tc.name, err)
+			continue
+		}
+		if !tc.ok {
+			continue
+		}
+
+		r, err := NewReader(buf)
+		if err != nil {
+			t.Errorf("NewReader: %v", err)
+			continue
+		}
+		_, err = ioutil.ReadAll(r)
+		if err != nil {
+			t.Errorf("ReadAll: %v", err)
+			continue
+		}
+		if r.Name != tc.name {
+			t.Errorf("name is %q, want %q", r.Name, tc.name)
+			continue
+		}
+		if err := r.Close(); err != nil {
+			t.Errorf("Reader.Close: %v", err)
+			continue
+		}
+	}
+}
+
+func TestWriterFlush(t *testing.T) {
+	buf := new(bytes.Buffer)
+
+	w := NewWriter(buf)
+	w.Comment = "comment"
+	w.Extra = []byte("extra")
+	w.ModTime = time.Unix(1e8, 0)
+	w.Name = "name"
+
+	n0 := buf.Len()
+	if n0 != 0 {
+		t.Fatalf("buffer size = %d before writes; want 0", n0)
+	}
+
+	if err := w.Flush(); err != nil {
+		t.Fatal(err)
+	}
+
+	n1 := buf.Len()
+	if n1 == 0 {
+		t.Fatal("no data after first flush")
+	}
+
+	w.Write([]byte("x"))
+
+	n2 := buf.Len()
+	if n1 != n2 {
+		t.Fatalf("after writing a single byte, size changed from %d to %d; want no change", n1, n2)
+	}
+
+	if err := w.Flush(); err != nil {
+		t.Fatal(err)
+	}
+
+	n3 := buf.Len()
+	if n2 == n3 {
+		t.Fatal("Flush didn't flush any data")
+	}
+}
+
+// Multiple gzip files concatenated form a valid gzip file.
+func TestConcat(t *testing.T) {
+	var buf bytes.Buffer
+	w := NewWriter(&buf)
+	w.Write([]byte("hello "))
+	w.Close()
+	w = NewWriter(&buf)
+	w.Write([]byte("world\n"))
+	w.Close()
+
+	r, err := NewReader(&buf)
+	data, err := ioutil.ReadAll(r)
+	if string(data) != "hello world\n" || err != nil {
+		t.Fatalf("ReadAll = %q, %v, want %q, nil", data, err, "hello world")
+	}
+}
+
+func TestWriterReset(t *testing.T) {
+	buf := new(bytes.Buffer)
+	buf2 := new(bytes.Buffer)
+	z := NewWriter(buf)
+	msg := []byte("hello world")
+	z.Write(msg)
+	z.Close()
+	z.Reset(buf2)
+	z.Write(msg)
+	z.Close()
+	if buf.String() != buf2.String() {
+		t.Errorf("buf2 %q != original buf of %q", buf2.String(), buf.String())
+	}
+}
diff --git a/src/compress/gzip/testdata/issue6550.gz b/src/compress/gzip/testdata/issue6550.gz
new file mode 100644
index 000000000..57972b636
--- /dev/null
+++ b/src/compress/gzip/testdata/issue6550.gz