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authorRuss Cox <rsc@golang.org>2014-09-08 00:08:51 -0400
committerRuss Cox <rsc@golang.org>2014-09-08 00:08:51 -0400
commit8528da672cc093d4dd06732819abc1f7b6b5a46e (patch)
tree334be80d4a4c85b77db6f6fdb67cbf0528cba5f5 /src/compress/gzip/gzip.go
parent73bcb69f272cbf34ddcc9daa56427a8683b5a95d (diff)
downloadgo-8528da672cc093d4dd06732819abc1f7b6b5a46e.tar.gz
build: move package sources from src/pkg to src
Preparation was in CL 134570043. This CL contains only the effect of 'hg mv src/pkg/* src'. For more about the move, see golang.org/s/go14nopkg.
Diffstat (limited to 'src/compress/gzip/gzip.go')
-rw-r--r--src/compress/gzip/gzip.go272
1 files changed, 272 insertions, 0 deletions
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
+}