FFmpeg
snappy.c
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1 /*
2  * Snappy decompression algorithm
3  * Copyright (c) 2015 Luca Barbato
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "libavutil/mem.h"
23 
24 #include "bytestream.h"
25 #include "snappy.h"
26 
27 enum {
32 };
33 
35 {
36  uint64_t val = 0;
37  int shift = 0;
38  int tmp;
39 
40  do {
41  tmp = bytestream2_get_byte(gb);
42  if (shift > 31 || ((tmp & 127LL) << shift) > INT_MAX)
43  return AVERROR_INVALIDDATA;
44  val |= (tmp & 127) << shift;
45  shift += 7;
46  } while (tmp & 128);
47 
48  return val;
49 }
50 
51 static int snappy_literal(GetByteContext *gb, uint8_t *p, int size, int val)
52 {
53  unsigned int len = 1;
54 
55  switch (val) {
56  case 63:
57  len += bytestream2_get_le32(gb);
58  break;
59  case 62:
60  len += bytestream2_get_le24(gb);
61  break;
62  case 61:
63  len += bytestream2_get_le16(gb);
64  break;
65  case 60:
66  len += bytestream2_get_byte(gb);
67  break;
68  default: // val < 60
69  len += val;
70  }
71 
72  if (size < len)
73  return AVERROR_INVALIDDATA;
74 
75  bytestream2_get_buffer(gb, p, len);
76 
77  return len;
78 }
79 
80 static int snappy_copy(uint8_t *start, uint8_t *p, int size,
81  unsigned int off, int len)
82 {
83  uint8_t *q;
84  int i;
85  if (off > p - start || size < len)
86  return AVERROR_INVALIDDATA;
87 
88  q = p - off;
89 
90  for (i = 0; i < len; i++)
91  p[i] = q[i];
92 
93  return len;
94 }
95 
96 static int snappy_copy1(GetByteContext *gb, uint8_t *start, uint8_t *p,
97  int size, int val)
98 {
99  int len = 4 + (val & 0x7);
100  unsigned int off = bytestream2_get_byte(gb) | (val & 0x38) << 5;
101 
102  return snappy_copy(start, p, size, off, len);
103 }
104 
105 static int snappy_copy2(GetByteContext *gb, uint8_t *start, uint8_t *p,
106  int size, int val)
107 {
108  int len = 1 + val;
109  unsigned int off = bytestream2_get_le16(gb);
110 
111  return snappy_copy(start, p, size, off, len);
112 }
113 
114 static int snappy_copy4(GetByteContext *gb, uint8_t *start, uint8_t *p,
115  int size, int val)
116 {
117  int len = 1 + val;
118  unsigned int off = bytestream2_get_le32(gb);
119 
120  return snappy_copy(start, p, size, off, len);
121 }
122 
123 static int64_t decode_len(GetByteContext *gb)
124 {
125  int64_t len = bytestream2_get_levarint(gb);
126 
127  if (len < 0 || len > UINT_MAX)
128  return AVERROR_INVALIDDATA;
129 
130  return len;
131 }
132 
134 {
136  int64_t len = decode_len(gb);
137 
138  bytestream2_seek(gb, -pos, SEEK_END);
139 
140  return len;
141 }
142 
144 {
145  int64_t len = decode_len(gb);
146  int ret = 0;
147  uint8_t *p;
148 
149  if (len < 0)
150  return len;
151 
152  if (len > *size)
154 
155  *size = len;
156  p = buf;
157 
158  while (bytestream2_get_bytes_left(gb) > 0) {
159  uint8_t s = bytestream2_get_byte(gb);
160  int val = s >> 2;
161 
162  switch (s & 0x03) {
163  case SNAPPY_LITERAL:
164  ret = snappy_literal(gb, p, len, val);
165  break;
166  case SNAPPY_COPY_1:
167  ret = snappy_copy1(gb, buf, p, len, val);
168  break;
169  case SNAPPY_COPY_2:
170  ret = snappy_copy2(gb, buf, p, len, val);
171  break;
172  case SNAPPY_COPY_4:
173  ret = snappy_copy4(gb, buf, p, len, val);
174  break;
175  }
176 
177  if (ret < 0)
178  return ret;
179 
180  p += ret;
181  len -= ret;
182  }
183 
184  return 0;
185 }
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
static int shift(int a, int b)
Definition: sonic.c:82
Memory handling functions.
static int snappy_copy(uint8_t *start, uint8_t *p, int size, unsigned int off, int len)
Definition: snappy.c:80
int64_t ff_snappy_peek_uncompressed_length(GetByteContext *gb)
Get the uncompressed length of an input buffer compressed using the Snappy algorithm.
Definition: snappy.c:133
uint8_t
ptrdiff_t size
Definition: opengl_enc.c:100
static av_always_inline int bytestream2_get_bytes_left(GetByteContext *g)
Definition: bytestream.h:154
static av_always_inline unsigned int bytestream2_get_buffer(GetByteContext *g, uint8_t *dst, unsigned int size)
Definition: bytestream.h:263
unsigned int pos
Definition: spdifenc.c:410
static int snappy_copy4(GetByteContext *gb, uint8_t *start, uint8_t *p, int size, int val)
Definition: snappy.c:114
int ff_snappy_uncompress(GetByteContext *gb, uint8_t *buf, int64_t *size)
Decompress an input buffer using Snappy algorithm.
Definition: snappy.c:143
#define AVERROR_BUFFER_TOO_SMALL
Buffer too small.
Definition: error.h:51
static int snappy_literal(GetByteContext *gb, uint8_t *p, int size, int val)
Definition: snappy.c:51
static int snappy_copy1(GetByteContext *gb, uint8_t *start, uint8_t *p, int size, int val)
Definition: snappy.c:96
#define s(width, name)
Definition: cbs_vp9.c:257
Snappy decompression.
static int64_t bytestream2_get_levarint(GetByteContext *gb)
Definition: snappy.c:34
static int snappy_copy2(GetByteContext *gb, uint8_t *start, uint8_t *p, int size, int val)
Definition: snappy.c:105
int len
static int64_t decode_len(GetByteContext *gb)
Definition: snappy.c:123
static av_always_inline int bytestream2_seek(GetByteContext *g, int offset, int whence)
Definition: bytestream.h:208
static double val(void *priv, double ch)
Definition: aeval.c:76
int i
Definition: input.c:407
static uint8_t tmp[11]
Definition: aes_ctr.c:26