2 * Snappy decompression algorithm
3 * Copyright (c) 2015 Luca Barbato
5 * This file is part of FFmpeg.
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.
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.
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
22 #include "libavutil/mem.h"
24 #include "bytestream.h"
34 static int64_t bytestream2_get_levarint(GetByteContext *gb)
41 tmp = bytestream2_get_byte(gb);
42 val |= (tmp & 127) << shift;
49 static int snappy_literal(GetByteContext *gb, uint8_t *p, int size, int val)
55 len += bytestream2_get_le32(gb);
58 len += bytestream2_get_le24(gb);
61 len += bytestream2_get_le16(gb);
64 len += bytestream2_get_byte(gb);
71 return AVERROR_INVALIDDATA;
73 bytestream2_get_buffer(gb, p, len);
78 static int snappy_copy(uint8_t *start, uint8_t *p, int size,
79 unsigned int off, int len)
83 if (off > p - start || size < len)
84 return AVERROR_INVALIDDATA;
88 for (i = 0; i < len; i++)
94 static int snappy_copy1(GetByteContext *gb, uint8_t *start, uint8_t *p,
97 int len = 4 + (val & 0x7);
98 unsigned int off = bytestream2_get_byte(gb) | (val & 0x38) << 5;
100 return snappy_copy(start, p, size, off, len);
103 static int snappy_copy2(GetByteContext *gb, uint8_t *start, uint8_t *p,
107 unsigned int off = bytestream2_get_le16(gb);
109 return snappy_copy(start, p, size, off, len);
112 static int snappy_copy4(GetByteContext *gb, uint8_t *start, uint8_t *p,
116 unsigned int off = bytestream2_get_le32(gb);
118 return snappy_copy(start, p, size, off, len);
121 static int64_t decode_len(GetByteContext *gb)
123 int64_t len = bytestream2_get_levarint(gb);
125 if (len < 0 || len > UINT_MAX)
126 return AVERROR_INVALIDDATA;
131 int64_t ff_snappy_peek_uncompressed_length(GetByteContext *gb)
133 int pos = bytestream2_get_bytes_left(gb);
134 int64_t len = decode_len(gb);
136 bytestream2_seek(gb, -pos, SEEK_END);
141 int ff_snappy_uncompress(GetByteContext *gb, uint8_t *buf, int64_t *size)
143 int64_t len = decode_len(gb);
151 return AVERROR_BUFFER_TOO_SMALL;
156 while (bytestream2_get_bytes_left(gb) > 0) {
157 uint8_t s = bytestream2_get_byte(gb);
162 ret = snappy_literal(gb, p, len, val);
165 ret = snappy_copy1(gb, buf, p, len, val);
168 ret = snappy_copy2(gb, buf, p, len, val);
171 ret = snappy_copy4(gb, buf, p, len, val);