1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
|
// Copyright 2014-2021 Ulrich Kunitz. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package lzma
import (
"bufio"
"errors"
"io"
)
// MinDictCap and MaxDictCap provide the range of supported dictionary
// capacities.
const (
MinDictCap = 1 << 12
MaxDictCap = 1<<32 - 1
)
// WriterConfig defines the configuration parameter for a writer.
type WriterConfig struct {
// Properties for the encoding. If the it is nil the value
// {LC: 3, LP: 0, PB: 2} will be chosen.
Properties *Properties
// The capacity of the dictionary. If DictCap is zero, the value
// 8 MiB will be chosen.
DictCap int
// Size of the lookahead buffer; value 0 indicates default size
// 4096
BufSize int
// Match algorithm
Matcher MatchAlgorithm
// SizeInHeader indicates that the header will contain an
// explicit size.
SizeInHeader bool
// Size of the data to be encoded. A positive value will imply
// than an explicit size will be set in the header.
Size int64
// EOSMarker requests whether the EOSMarker needs to be written.
// If no explicit size is been given the EOSMarker will be
// set automatically.
EOSMarker bool
}
// fill converts zero-value fields to their explicit default values.
func (c *WriterConfig) fill() {
if c.Properties == nil {
c.Properties = &Properties{LC: 3, LP: 0, PB: 2}
}
if c.DictCap == 0 {
c.DictCap = 8 * 1024 * 1024
}
if c.BufSize == 0 {
c.BufSize = 4096
}
if c.Size > 0 {
c.SizeInHeader = true
}
if !c.SizeInHeader {
c.EOSMarker = true
}
}
// Verify checks WriterConfig for errors. Verify will replace zero
// values with default values.
func (c *WriterConfig) Verify() error {
c.fill()
var err error
if c == nil {
return errors.New("lzma: WriterConfig is nil")
}
if c.Properties == nil {
return errors.New("lzma: WriterConfig has no Properties set")
}
if err = c.Properties.verify(); err != nil {
return err
}
if !(MinDictCap <= c.DictCap && int64(c.DictCap) <= MaxDictCap) {
return errors.New("lzma: dictionary capacity is out of range")
}
if !(maxMatchLen <= c.BufSize) {
return errors.New("lzma: lookahead buffer size too small")
}
if c.SizeInHeader {
if c.Size < 0 {
return errors.New("lzma: negative size not supported")
}
} else if !c.EOSMarker {
return errors.New("lzma: EOS marker is required")
}
if err = c.Matcher.verify(); err != nil {
return err
}
return nil
}
// header returns the header structure for this configuration.
func (c *WriterConfig) header() header {
h := header{
properties: *c.Properties,
dictCap: c.DictCap,
size: -1,
}
if c.SizeInHeader {
h.size = c.Size
}
return h
}
// Writer writes an LZMA stream in the classic format.
type Writer struct {
h header
bw io.ByteWriter
buf *bufio.Writer
e *encoder
}
// NewWriter creates a new LZMA writer for the classic format. The
// method will write the header to the underlying stream.
func (c WriterConfig) NewWriter(lzma io.Writer) (w *Writer, err error) {
if err = c.Verify(); err != nil {
return nil, err
}
w = &Writer{h: c.header()}
var ok bool
w.bw, ok = lzma.(io.ByteWriter)
if !ok {
w.buf = bufio.NewWriter(lzma)
w.bw = w.buf
}
state := newState(w.h.properties)
m, err := c.Matcher.new(w.h.dictCap)
if err != nil {
return nil, err
}
dict, err := newEncoderDict(w.h.dictCap, c.BufSize, m)
if err != nil {
return nil, err
}
var flags encoderFlags
if c.EOSMarker {
flags = eosMarker
}
if w.e, err = newEncoder(w.bw, state, dict, flags); err != nil {
return nil, err
}
if err = w.writeHeader(); err != nil {
return nil, err
}
return w, nil
}
// NewWriter creates a new LZMA writer using the classic format. The
// function writes the header to the underlying stream.
func NewWriter(lzma io.Writer) (w *Writer, err error) {
return WriterConfig{}.NewWriter(lzma)
}
// writeHeader writes the LZMA header into the stream.
func (w *Writer) writeHeader() error {
data, err := w.h.marshalBinary()
if err != nil {
return err
}
_, err = w.bw.(io.Writer).Write(data)
return err
}
// Write puts data into the Writer.
func (w *Writer) Write(p []byte) (n int, err error) {
if w.h.size >= 0 {
m := w.h.size
m -= w.e.Compressed() + int64(w.e.dict.Buffered())
if m < 0 {
m = 0
}
if m < int64(len(p)) {
p = p[:m]
err = ErrNoSpace
}
}
var werr error
if n, werr = w.e.Write(p); werr != nil {
err = werr
}
return n, err
}
// Close closes the writer stream. It ensures that all data from the
// buffer will be compressed and the LZMA stream will be finished.
func (w *Writer) Close() error {
if w.h.size >= 0 {
n := w.e.Compressed() + int64(w.e.dict.Buffered())
if n != w.h.size {
return errSize
}
}
err := w.e.Close()
if w.buf != nil {
ferr := w.buf.Flush()
if err == nil {
err = ferr
}
}
return err
}
|
