compress/zlib: use binary.BigEndian consistently

One major reason to avoid binary.BigEndian is because
the binary package includes a transitive dependency on reflect.
See #54097.

Given that writer.go already depends on the binary package,
embrace use of it consistently where sensible.
We should either embrace use of binary or fully avoid it.

Change-Id: I5f2d27d0ed8cab5ac54be02362c7d33276dd4b9a
Reviewed-on: https://go-review.googlesource.com/c/go/+/452176
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Joseph Tsai <joetsai@digital-static.net>
Auto-Submit: Joseph Tsai <joetsai@digital-static.net>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

diff --git a/src/compress/zlib/reader.go b/src/compress/zlib/reader.go
index 343a18bf68150e54f1c39945b23b2a356542991a..10954eaad784d58caa49cf8c706b50e32281caad 100644 (file)
--- a/src/compress/zlib/reader.go
+++ b/src/compress/zlib/reader.go
@@ -26,6 +26,7 @@ package zlib
 import (
        "bufio"
        "compress/flate"
+       "encoding/binary"
        "errors"
        "hash"
        "hash/adler32"
@@ -110,7 +111,7 @@ 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
@@ -145,7 +146,7 @@ func (z *reader) Reset(r io.Reader, dict []byte) error {
                }
                return z.err
        }
-       h := uint(z.scratch[0])<<8 | uint(z.scratch[1])
+       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
@@ -159,7 +160,7 @@ 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

diff --git a/src/compress/zlib/writer.go b/src/compress/zlib/writer.go
index 9986e3834d4d0963e98642eb0afc3f8921a65942..c65e80f742364ef81b94d8764dd38a0c64b9f162 100644 (file)
--- a/src/compress/zlib/writer.go
+++ b/src/compress/zlib/writer.go
@@ -115,7 +115,7 @@ 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
        }