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
|
/*
* Snappy decompression algorithm
* Copyright (c) 2015 Luca Barbato
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/mem.h"
#include "bytestream.h"
#include "snappy.h"
enum {
SNAPPY_LITERAL,
SNAPPY_COPY_1,
SNAPPY_COPY_2,
SNAPPY_COPY_4,
};
static int64_t bytestream2_get_levarint(GetByteContext *gb)
{
uint64_t val = 0;
int shift = 0;
int tmp;
do {
tmp = bytestream2_get_byte(gb);
val |= (tmp & 127) << shift;
shift += 7;
} while (tmp & 128);
return val;
}
static int snappy_literal(GetByteContext *gb, uint8_t *p, int size, int val)
{
unsigned int len = 1;
switch (val) {
case 63:
len += bytestream2_get_le32(gb);
break;
case 62:
len += bytestream2_get_le24(gb);
break;
case 61:
len += bytestream2_get_le16(gb);
break;
case 60:
len += bytestream2_get_byte(gb);
break;
default: // val < 60
len += val;
}
if (size < len)
return AVERROR_INVALIDDATA;
bytestream2_get_buffer(gb, p, len);
return len;
}
static int snappy_copy(uint8_t *start, uint8_t *p, int size,
unsigned int off, int len)
{
uint8_t *q;
int i;
if (off > p - start || size < len)
return AVERROR_INVALIDDATA;
q = p - off;
for (i = 0; i < len; i++)
p[i] = q[i];
return len;
}
static int snappy_copy1(GetByteContext *gb, uint8_t *start, uint8_t *p,
int size, int val)
{
int len = 4 + (val & 0x7);
unsigned int off = bytestream2_get_byte(gb) | (val & 0x38) << 5;
return snappy_copy(start, p, size, off, len);
}
static int snappy_copy2(GetByteContext *gb, uint8_t *start, uint8_t *p,
int size, int val)
{
int len = 1 + val;
unsigned int off = bytestream2_get_le16(gb);
return snappy_copy(start, p, size, off, len);
}
static int snappy_copy4(GetByteContext *gb, uint8_t *start, uint8_t *p,
int size, int val)
{
int len = 1 + val;
unsigned int off = bytestream2_get_le32(gb);
return snappy_copy(start, p, size, off, len);
}
static int64_t decode_len(GetByteContext *gb)
{
int64_t len = bytestream2_get_levarint(gb);
if (len < 0 || len > UINT_MAX)
return AVERROR_INVALIDDATA;
return len;
}
int ff_snappy_uncompress(GetByteContext *gb, uint8_t **buf, int64_t *size)
{
int64_t len = decode_len(gb);
int ret = 0;
uint8_t *p;
if (len < 0)
return len;
if ((ret = av_reallocp(buf, len)) < 0)
return AVERROR(ENOMEM);
*size = len;
p = *buf;
while (bytestream2_get_bytes_left(gb) > 0) {
uint8_t s = bytestream2_get_byte(gb);
int val = s >> 2;
switch (s & 0x03) {
case SNAPPY_LITERAL:
ret = snappy_literal(gb, p, len, val);
break;
case SNAPPY_COPY_1:
ret = snappy_copy1(gb, *buf, p, len, val);
break;
case SNAPPY_COPY_2:
ret = snappy_copy2(gb, *buf, p, len, val);
break;
case SNAPPY_COPY_4:
ret = snappy_copy4(gb, *buf, p, len, val);
break;
}
if (ret < 0)
return ret;
p += ret;
len -= ret;
}
return 0;
}
|
