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-rw-r--r--vendor/golang.org/x/crypto/openpgp/packet/compressed.go123
1 files changed, 123 insertions, 0 deletions
diff --git a/vendor/golang.org/x/crypto/openpgp/packet/compressed.go b/vendor/golang.org/x/crypto/openpgp/packet/compressed.go
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1// Copyright 2011 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package packet
6
7import (
8 "compress/bzip2"
9 "compress/flate"
10 "compress/zlib"
11 "golang.org/x/crypto/openpgp/errors"
12 "io"
13 "strconv"
14)
15
16// Compressed represents a compressed OpenPGP packet. The decompressed contents
17// will contain more OpenPGP packets. See RFC 4880, section 5.6.
18type Compressed struct {
19 Body io.Reader
20}
21
22const (
23 NoCompression = flate.NoCompression
24 BestSpeed = flate.BestSpeed
25 BestCompression = flate.BestCompression
26 DefaultCompression = flate.DefaultCompression
27)
28
29// CompressionConfig contains compressor configuration settings.
30type CompressionConfig struct {
31 // Level is the compression level to use. It must be set to
32 // between -1 and 9, with -1 causing the compressor to use the
33 // default compression level, 0 causing the compressor to use
34 // no compression and 1 to 9 representing increasing (better,
35 // slower) compression levels. If Level is less than -1 or
36 // more then 9, a non-nil error will be returned during
37 // encryption. See the constants above for convenient common
38 // settings for Level.
39 Level int
40}
41
42func (c *Compressed) parse(r io.Reader) error {
43 var buf [1]byte
44 _, err := readFull(r, buf[:])
45 if err != nil {
46 return err
47 }
48
49 switch buf[0] {
50 case 1:
51 c.Body = flate.NewReader(r)
52 case 2:
53 c.Body, err = zlib.NewReader(r)
54 case 3:
55 c.Body = bzip2.NewReader(r)
56 default:
57 err = errors.UnsupportedError("unknown compression algorithm: " + strconv.Itoa(int(buf[0])))
58 }
59
60 return err
61}
62
63// compressedWriterCloser represents the serialized compression stream
64// header and the compressor. Its Close() method ensures that both the
65// compressor and serialized stream header are closed. Its Write()
66// method writes to the compressor.
67type compressedWriteCloser struct {
68 sh io.Closer // Stream Header
69 c io.WriteCloser // Compressor
70}
71
72func (cwc compressedWriteCloser) Write(p []byte) (int, error) {
73 return cwc.c.Write(p)
74}
75
76func (cwc compressedWriteCloser) Close() (err error) {
77 err = cwc.c.Close()
78 if err != nil {
79 return err
80 }
81
82 return cwc.sh.Close()
83}
84
85// SerializeCompressed serializes a compressed data packet to w and
86// returns a WriteCloser to which the literal data packets themselves
87// can be written and which MUST be closed on completion. If cc is
88// nil, sensible defaults will be used to configure the compression
89// algorithm.
90func SerializeCompressed(w io.WriteCloser, algo CompressionAlgo, cc *CompressionConfig) (literaldata io.WriteCloser, err error) {
91 compressed, err := serializeStreamHeader(w, packetTypeCompressed)
92 if err != nil {
93 return
94 }
95
96 _, err = compressed.Write([]byte{uint8(algo)})
97 if err != nil {
98 return
99 }
100
101 level := DefaultCompression
102 if cc != nil {
103 level = cc.Level
104 }
105
106 var compressor io.WriteCloser
107 switch algo {
108 case CompressionZIP:
109 compressor, err = flate.NewWriter(compressed, level)
110 case CompressionZLIB:
111 compressor, err = zlib.NewWriterLevel(compressed, level)
112 default:
113 s := strconv.Itoa(int(algo))
114 err = errors.UnsupportedError("Unsupported compression algorithm: " + s)
115 }
116 if err != nil {
117 return
118 }
119
120 literaldata = compressedWriteCloser{compressed, compressor}
121
122 return
123}