blob: 7900b0f978535490425b9b2bb9828a39f96739cb
| 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 { |
| 28 | SNAPPY_LITERAL, |
| 29 | SNAPPY_COPY_1, |
| 30 | SNAPPY_COPY_2, |
| 31 | SNAPPY_COPY_4, |
| 32 | }; |
| 33 | |
| 34 | static int64_t bytestream2_get_levarint(GetByteContext *gb) |
| 35 | { |
| 36 | uint64_t val = 0; |
| 37 | int shift = 0; |
| 38 | int tmp; |
| 39 | |
| 40 | do { |
| 41 | tmp = bytestream2_get_byte(gb); |
| 42 | val |= (tmp & 127) << shift; |
| 43 | shift += 7; |
| 44 | } while (tmp & 128); |
| 45 | |
| 46 | return val; |
| 47 | } |
| 48 | |
| 49 | static int snappy_literal(GetByteContext *gb, uint8_t *p, int size, int val) |
| 50 | { |
| 51 | unsigned int len = 1; |
| 52 | |
| 53 | switch (val) { |
| 54 | case 63: |
| 55 | len += bytestream2_get_le32(gb); |
| 56 | break; |
| 57 | case 62: |
| 58 | len += bytestream2_get_le24(gb); |
| 59 | break; |
| 60 | case 61: |
| 61 | len += bytestream2_get_le16(gb); |
| 62 | break; |
| 63 | case 60: |
| 64 | len += bytestream2_get_byte(gb); |
| 65 | break; |
| 66 | default: // val < 60 |
| 67 | len += val; |
| 68 | } |
| 69 | |
| 70 | if (size < len) |
| 71 | return AVERROR_INVALIDDATA; |
| 72 | |
| 73 | bytestream2_get_buffer(gb, p, len); |
| 74 | |
| 75 | return len; |
| 76 | } |
| 77 | |
| 78 | static int snappy_copy(uint8_t *start, uint8_t *p, int size, |
| 79 | unsigned int off, int len) |
| 80 | { |
| 81 | uint8_t *q; |
| 82 | int i; |
| 83 | if (off > p - start || size < len) |
| 84 | return AVERROR_INVALIDDATA; |
| 85 | |
| 86 | q = p - off; |
| 87 | |
| 88 | for (i = 0; i < len; i++) |
| 89 | p[i] = q[i]; |
| 90 | |
| 91 | return len; |
| 92 | } |
| 93 | |
| 94 | static int snappy_copy1(GetByteContext *gb, uint8_t *start, uint8_t *p, |
| 95 | int size, int val) |
| 96 | { |
| 97 | int len = 4 + (val & 0x7); |
| 98 | unsigned int off = bytestream2_get_byte(gb) | (val & 0x38) << 5; |
| 99 | |
| 100 | return snappy_copy(start, p, size, off, len); |
| 101 | } |
| 102 | |
| 103 | static int snappy_copy2(GetByteContext *gb, uint8_t *start, uint8_t *p, |
| 104 | int size, int val) |
| 105 | { |
| 106 | int len = 1 + val; |
| 107 | unsigned int off = bytestream2_get_le16(gb); |
| 108 | |
| 109 | return snappy_copy(start, p, size, off, len); |
| 110 | } |
| 111 | |
| 112 | static int snappy_copy4(GetByteContext *gb, uint8_t *start, uint8_t *p, |
| 113 | int size, int val) |
| 114 | { |
| 115 | int len = 1 + val; |
| 116 | unsigned int off = bytestream2_get_le32(gb); |
| 117 | |
| 118 | return snappy_copy(start, p, size, off, len); |
| 119 | } |
| 120 | |
| 121 | static int64_t decode_len(GetByteContext *gb) |
| 122 | { |
| 123 | int64_t len = bytestream2_get_levarint(gb); |
| 124 | |
| 125 | if (len < 0 || len > UINT_MAX) |
| 126 | return AVERROR_INVALIDDATA; |
| 127 | |
| 128 | return len; |
| 129 | } |
| 130 | |
| 131 | int64_t ff_snappy_peek_uncompressed_length(GetByteContext *gb) |
| 132 | { |
| 133 | int pos = bytestream2_get_bytes_left(gb); |
| 134 | int64_t len = decode_len(gb); |
| 135 | |
| 136 | bytestream2_seek(gb, -pos, SEEK_END); |
| 137 | |
| 138 | return len; |
| 139 | } |
| 140 | |
| 141 | int ff_snappy_uncompress(GetByteContext *gb, uint8_t *buf, int64_t *size) |
| 142 | { |
| 143 | int64_t len = decode_len(gb); |
| 144 | int ret = 0; |
| 145 | uint8_t *p; |
| 146 | |
| 147 | if (len < 0) |
| 148 | return len; |
| 149 | |
| 150 | if (len > *size) |
| 151 | return AVERROR_BUFFER_TOO_SMALL; |
| 152 | |
| 153 | *size = len; |
| 154 | p = buf; |
| 155 | |
| 156 | while (bytestream2_get_bytes_left(gb) > 0) { |
| 157 | uint8_t s = bytestream2_get_byte(gb); |
| 158 | int val = s >> 2; |
| 159 | |
| 160 | switch (s & 0x03) { |
| 161 | case SNAPPY_LITERAL: |
| 162 | ret = snappy_literal(gb, p, len, val); |
| 163 | break; |
| 164 | case SNAPPY_COPY_1: |
| 165 | ret = snappy_copy1(gb, buf, p, len, val); |
| 166 | break; |
| 167 | case SNAPPY_COPY_2: |
| 168 | ret = snappy_copy2(gb, buf, p, len, val); |
| 169 | break; |
| 170 | case SNAPPY_COPY_4: |
| 171 | ret = snappy_copy4(gb, buf, p, len, val); |
| 172 | break; |
| 173 | } |
| 174 | |
| 175 | if (ret < 0) |
| 176 | return ret; |
| 177 | |
| 178 | p += ret; |
| 179 | len -= ret; |
| 180 | } |
| 181 | |
| 182 | return 0; |
| 183 | } |
| 184 |