Upgrade zlib to upstream (#971)

Mostly cosmetic changes.

zlib/reader.go

@@ -26,14 +26,18 @@ package zlib
 import (
 	"bufio"
 	"compress/zlib"
+	"encoding/binary"
 	"hash"
 	"hash/adler32"
 	"io"
 
 	"github.com/klauspost/compress/flate"
 )
 
-const zlibDeflate = 8
+const (
+	zlibDeflate   = 8
+	zlibMaxWindow = 7
+)
 
 var (
 	// ErrChecksum is returned when reading ZLIB data that has an invalid checksum.
@@ -52,7 +56,7 @@ type reader struct {
 	scratch      [4]byte
 }
 
-// Resetter resets a ReadCloser returned by NewReader or NewReaderDict to
+// Resetter resets a ReadCloser returned by [NewReader] or [NewReaderDict]
 // to switch to a new underlying Reader. This permits reusing a ReadCloser
 // instead of allocating a new one.
 type Resetter interface {
@@ -63,20 +67,20 @@ type Resetter interface {
 
 // NewReader creates a new ReadCloser.
 // Reads from the returned ReadCloser read and decompress data from r.
-// If r does not implement io.ByteReader, the decompressor may read more
+// If r does not implement [io.ByteReader], the decompressor may read more
 // data than necessary from r.
 // It is the caller's responsibility to call Close on the ReadCloser when done.
 //
-// The ReadCloser returned by NewReader also implements Resetter.
+// The [io.ReadCloser] returned by NewReader also implements [Resetter].
 func NewReader(r io.Reader) (io.ReadCloser, error) {
 	return NewReaderDict(r, nil)
 }
 
-// NewReaderDict is like NewReader but uses a preset dictionary.
+// NewReaderDict is like [NewReader] but uses a preset dictionary.
 // NewReaderDict ignores the dictionary if the compressed data does not refer to it.
-// If the compressed data refers to a different dictionary, NewReaderDict returns ErrDictionary.
+// If the compressed data refers to a different dictionary, NewReaderDict returns [ErrDictionary].
 //
-// The ReadCloser returned by NewReaderDict also implements Resetter.
+// The ReadCloser returned by NewReaderDict also implements [Resetter].
 func NewReaderDict(r io.Reader, dict []byte) (io.ReadCloser, error) {
 	z := new(reader)
 	err := z.Reset(r, dict)
@@ -108,17 +112,17 @@ func (z *reader) Read(p []byte) (int, error) {
 		return n, z.err
 	}
 	// ZLIB (RFC 1950) is big-endian, unlike GZIP (RFC 1952).
-	checksum := uint32(z.scratch[0])<<24 | uint32(z.scratch[1])<<16 | uint32(z.scratch[2])<<8 | uint32(z.scratch[3])
+	checksum := binary.BigEndian.Uint32(z.scratch[:4])
 	if checksum != z.digest.Sum32() {
 		z.err = ErrChecksum
 		return n, z.err
 	}
 	return n, io.EOF
 }
 
-// Calling Close does not close the wrapped io.Reader originally passed to NewReader.
+// Calling Close does not close the wrapped [io.Reader] originally passed to [NewReader].
 // In order for the ZLIB checksum to be verified, the reader must be
-// fully consumed until the io.EOF.
+// fully consumed until the [io.EOF].
 func (z *reader) Close() error {
 	if z.err != nil && z.err != io.EOF {
 		return z.err
@@ -128,7 +132,7 @@ func (z *reader) Close() error {
 }
 
 func (z *reader) Reset(r io.Reader, dict []byte) error {
-	*z = reader{decompressor: z.decompressor, digest: z.digest}
+	*z = reader{decompressor: z.decompressor}
 	if fr, ok := r.(flate.Reader); ok {
 		z.r = fr
 	} else {
@@ -143,8 +147,8 @@ func (z *reader) Reset(r io.Reader, dict []byte) error {
 		}
 		return z.err
 	}
-	h := uint(z.scratch[0])<<8 | uint(z.scratch[1])
-	if (z.scratch[0]&0x0f != zlibDeflate) || (h%31 != 0) {
+	h := binary.BigEndian.Uint16(z.scratch[:2])
+	if (z.scratch[0]&0x0f != zlibDeflate) || (z.scratch[0]>>4 > zlibMaxWindow) || (h%31 != 0) {
 		z.err = ErrHeader
 		return z.err
 	}
@@ -157,7 +161,7 @@ func (z *reader) Reset(r io.Reader, dict []byte) error {
 			}
 			return z.err
 		}
-		checksum := uint32(z.scratch[0])<<24 | uint32(z.scratch[1])<<16 | uint32(z.scratch[2])<<8 | uint32(z.scratch[3])
+		checksum := binary.BigEndian.Uint32(z.scratch[:4])
 		if checksum != adler32.Checksum(dict) {
 			z.err = ErrDictionary
 			return z.err

zlib/reader_test.go

@@ -19,7 +19,7 @@ type zlibTest struct {
 }
 
 // Compare-to-golden test data was generated by the ZLIB example program at
-// http://www.zlib.net/zpipe.c
+// https://www.zlib.net/zpipe.c
 
 var zlibTests = []zlibTest{
 	{
@@ -65,7 +65,14 @@ var zlibTests = []zlibTest{
 		nil,
 	},
 	{
-		"bad header",
+		"bad header (CINFO)",
+		"",
+		[]byte{0x88, 0x98, 0x03, 0x00, 0x00, 0x00, 0x00, 0x01},
+		nil,
+		ErrHeader,
+	},
+	{
+		"bad header (FCHECK)",
 		"",
 		[]byte{0x78, 0x9f, 0x03, 0x00, 0x00, 0x00, 0x00, 0x01},
 		nil,

zlib/writer.go

@@ -5,6 +5,7 @@
 package zlib
 
 import (
+	"encoding/binary"
 	"fmt"
 	"hash"
 	"hash/adler32"
@@ -20,7 +21,7 @@ const (
 	BestSpeed           = flate.BestSpeed
 	BestCompression     = flate.BestCompression
 	DefaultCompression  = flate.DefaultCompression
-	ConstantCompression = flate.ConstantCompression
+	ConstantCompression = flate.ConstantCompression // Deprecated: Use HuffmanOnly.
 	HuffmanOnly         = flate.HuffmanOnly
 )
 
@@ -40,7 +41,7 @@ type Writer struct {
 // NewWriter creates 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.
+// It is the caller's responsibility to call Close on the Writer when done.
 // Writes may be buffered and not flushed until Close.
 func NewWriter(w io.Writer) *Writer {
 	z, _ := NewWriterLevelDict(w, DefaultCompression, nil)
@@ -116,17 +117,13 @@ func (z *Writer) writeHeader() (err error) {
 	if z.dict != nil {
 		z.scratch[1] |= 1 << 5
 	}
-	z.scratch[1] += uint8(31 - (uint16(z.scratch[0])<<8+uint16(z.scratch[1]))%31)
+	z.scratch[1] += uint8(31 - binary.BigEndian.Uint16(z.scratch[:2])%31)
 	if _, err = z.w.Write(z.scratch[0:2]); err != nil {
 		return err
 	}
 	if z.dict != nil {
 		// The next four bytes are the Adler-32 checksum of the dictionary.
-		checksum := adler32.Checksum(z.dict)
-		z.scratch[0] = uint8(checksum >> 24)
-		z.scratch[1] = uint8(checksum >> 16)
-		z.scratch[2] = uint8(checksum >> 8)
-		z.scratch[3] = uint8(checksum >> 0)
+		binary.BigEndian.PutUint32(z.scratch[:], adler32.Checksum(z.dict))
 		if _, err = z.w.Write(z.scratch[0:4]); err != nil {
 			return err
 		}
@@ -192,10 +189,7 @@ func (z *Writer) Close() error {
 	}
 	checksum := z.digest.Sum32()
 	// ZLIB (RFC 1950) is big-endian, unlike GZIP (RFC 1952).
-	z.scratch[0] = uint8(checksum >> 24)
-	z.scratch[1] = uint8(checksum >> 16)
-	z.scratch[2] = uint8(checksum >> 8)
-	z.scratch[3] = uint8(checksum >> 0)
+	binary.BigEndian.PutUint32(z.scratch[:], checksum)
 	_, z.err = z.w.Write(z.scratch[0:4])
 	return z.err
 }

zlib/writer_test.go

@@ -153,24 +153,36 @@ func TestWriter(t *testing.T) {
 }
 
 func TestWriterBig(t *testing.T) {
-	for _, fn := range filenames {
+	for i, fn := range filenames {
 		testFileLevelDict(t, fn, DefaultCompression, "")
 		testFileLevelDict(t, fn, NoCompression, "")
 		testFileLevelDict(t, fn, HuffmanOnly, "")
 		for level := BestSpeed; level <= BestCompression; level++ {
 			testFileLevelDict(t, fn, level, "")
+			if level >= 1 && testing.Short() {
+				break
+			}
+		}
+		if i == 0 && testing.Short() {
+			break
 		}
 	}
 }
 
 func TestWriterDict(t *testing.T) {
 	const dictionary = "0123456789."
-	for _, fn := range filenames {
+	for i, fn := range filenames {
 		testFileLevelDict(t, fn, DefaultCompression, dictionary)
 		testFileLevelDict(t, fn, NoCompression, dictionary)
 		testFileLevelDict(t, fn, HuffmanOnly, dictionary)
 		for level := BestSpeed; level <= BestCompression; level++ {
 			testFileLevelDict(t, fn, level, dictionary)
+			if level >= 1 && testing.Short() {
+				break
+			}
+		}
+		if i == 0 && testing.Short() {
+			break
 		}
 	}
 }