Make sure we do not accidentially "fix" cnt to something < 0
[libav.git] / libavutil / lzo.c
1 /*
2 * LZO 1x decompression
3 * Copyright (c) 2006 Reimar Doeffinger
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 #include "common.h"
22 //! avoid e.g. MPlayers fast_memcpy, it slows things down here
23 #undef memcpy
24 #include <string.h>
25 #include "lzo.h"
26
27 //! define if we may write up to 12 bytes beyond the output buffer
28 #define OUTBUF_PADDED 1
29 //! define if we may read up to 8 bytes beyond the input buffer
30 #define INBUF_PADDED 1
31 typedef struct LZOContext {
32 uint8_t *in, *in_end;
33 uint8_t *out_start, *out, *out_end;
34 int error;
35 } LZOContext;
36
37 /**
38 * \brief read one byte from input buffer, avoiding overrun
39 * \return byte read
40 */
41 static inline int get_byte(LZOContext *c) {
42 if (c->in < c->in_end)
43 return *c->in++;
44 c->error |= LZO_INPUT_DEPLETED;
45 return 1;
46 }
47
48 #ifdef INBUF_PADDED
49 #define GETB(c) (*(c).in++)
50 #else
51 #define GETB(c) get_byte(&(c))
52 #endif
53
54 /**
55 * \brief decode a length value in the coding used by lzo
56 * \param x previous byte value
57 * \param mask bits used from x
58 * \return decoded length value
59 */
60 static inline int get_len(LZOContext *c, int x, int mask) {
61 int cnt = x & mask;
62 if (!cnt) {
63 while (!(x = get_byte(c))) cnt += 255;
64 cnt += mask + x;
65 }
66 return cnt;
67 }
68
69 //#define UNALIGNED_LOADSTORE
70 #define BUILTIN_MEMCPY
71 #ifdef UNALIGNED_LOADSTORE
72 #define COPY2(d, s) *(uint16_t *)(d) = *(uint16_t *)(s);
73 #define COPY4(d, s) *(uint32_t *)(d) = *(uint32_t *)(s);
74 #elif defined(BUILTIN_MEMCPY)
75 #define COPY2(d, s) memcpy(d, s, 2);
76 #define COPY4(d, s) memcpy(d, s, 4);
77 #else
78 #define COPY2(d, s) (d)[0] = (s)[0]; (d)[1] = (s)[1];
79 #define COPY4(d, s) (d)[0] = (s)[0]; (d)[1] = (s)[1]; (d)[2] = (s)[2]; (d)[3] = (s)[3];
80 #endif
81
82 /**
83 * \brief copy bytes from input to output buffer with checking
84 * \param cnt number of bytes to copy, must be >= 0
85 */
86 static inline void copy(LZOContext *c, int cnt) {
87 register uint8_t *src = c->in;
88 register uint8_t *dst = c->out;
89 if (cnt > c->in_end - src) {
90 cnt = FFMAX(c->in_end - src, 0);
91 c->error |= LZO_INPUT_DEPLETED;
92 }
93 if (cnt > c->out_end - dst) {
94 cnt = FFMAX(c->out_end - dst, 0);
95 c->error |= LZO_OUTPUT_FULL;
96 }
97 #if defined(INBUF_PADDED) && defined(OUTBUF_PADDED)
98 COPY4(dst, src);
99 src += 4;
100 dst += 4;
101 cnt -= 4;
102 if (cnt > 0)
103 #endif
104 memcpy(dst, src, cnt);
105 c->in = src + cnt;
106 c->out = dst + cnt;
107 }
108
109 /**
110 * \brief copy previously decoded bytes to current position
111 * \param back how many bytes back we start
112 * \param cnt number of bytes to copy, must be >= 0
113 *
114 * cnt > back is valid, this will copy the bytes we just copied,
115 * thus creating a repeating pattern with a period length of back.
116 */
117 static inline void copy_backptr(LZOContext *c, int back, int cnt) {
118 register uint8_t *src = &c->out[-back];
119 register uint8_t *dst = c->out;
120 if (src < c->out_start || src > dst) {
121 c->error |= LZO_INVALID_BACKPTR;
122 return;
123 }
124 if (cnt > c->out_end - dst) {
125 cnt = FFMAX(c->out_end - dst, 0);
126 c->error |= LZO_OUTPUT_FULL;
127 }
128 if (back == 1) {
129 memset(dst, *src, cnt);
130 dst += cnt;
131 } else {
132 #ifdef OUTBUF_PADDED
133 COPY2(dst, src);
134 COPY2(dst + 2, src + 2);
135 src += 4;
136 dst += 4;
137 cnt -= 4;
138 if (cnt > 0) {
139 COPY2(dst, src);
140 COPY2(dst + 2, src + 2);
141 COPY2(dst + 4, src + 4);
142 COPY2(dst + 6, src + 6);
143 src += 8;
144 dst += 8;
145 cnt -= 8;
146 }
147 #endif
148 if (cnt > 0) {
149 int blocklen = back;
150 while (cnt > blocklen) {
151 memcpy(dst, src, blocklen);
152 dst += blocklen;
153 cnt -= blocklen;
154 blocklen <<= 1;
155 }
156 memcpy(dst, src, cnt);
157 }
158 dst += cnt;
159 }
160 c->out = dst;
161 }
162
163 /**
164 * \brief decode LZO 1x compressed data
165 * \param out output buffer
166 * \param outlen size of output buffer, number of bytes left are returned here
167 * \param in input buffer
168 * \param inlen size of input buffer, number of bytes left are returned here
169 * \return 0 on success, otherwise error flags, see lzo.h
170 *
171 * make sure all buffers are appropriately padded, in must provide
172 * LZO_INPUT_PADDING, out must provide LZO_OUTPUT_PADDING additional bytes
173 */
174 int lzo1x_decode(void *out, int *outlen, void *in, int *inlen) {
175 int state= 0;
176 int x;
177 LZOContext c;
178 c.in = in;
179 c.in_end = (uint8_t *)in + *inlen;
180 c.out = c.out_start = out;
181 c.out_end = (uint8_t *)out + * outlen;
182 c.error = 0;
183 x = GETB(c);
184 if (x > 17) {
185 copy(&c, x - 17);
186 x = GETB(c);
187 if (x < 16) c.error |= LZO_ERROR;
188 }
189 if (c.in > c.in_end)
190 c.error |= LZO_INPUT_DEPLETED;
191 while (!c.error) {
192 int cnt, back;
193 if (x > 15) {
194 if (x > 63) {
195 cnt = (x >> 5) - 1;
196 back = (GETB(c) << 3) + ((x >> 2) & 7) + 1;
197 } else if (x > 31) {
198 cnt = get_len(&c, x, 31);
199 x = GETB(c);
200 back = (GETB(c) << 6) + (x >> 2) + 1;
201 } else {
202 cnt = get_len(&c, x, 7);
203 back = (1 << 14) + ((x & 8) << 11);
204 x = GETB(c);
205 back += (GETB(c) << 6) + (x >> 2);
206 if (back == (1 << 14)) {
207 if (cnt != 1)
208 c.error |= LZO_ERROR;
209 break;
210 }
211 }
212 } else if(!state){
213 cnt = get_len(&c, x, 15);
214 copy(&c, cnt + 3);
215 x = GETB(c);
216 if (x > 15)
217 continue;
218 cnt = 1;
219 back = (1 << 11) + (GETB(c) << 2) + (x >> 2) + 1;
220 } else {
221 cnt = 0;
222 back = (GETB(c) << 2) + (x >> 2) + 1;
223 }
224 copy_backptr(&c, back, cnt + 2);
225 state=
226 cnt = x & 3;
227 copy(&c, cnt);
228 x = GETB(c);
229 }
230 *inlen = c.in_end - c.in;
231 if (c.in > c.in_end)
232 *inlen = 0;
233 *outlen = c.out_end - c.out;
234 return c.error;
235 }
236
237 #ifdef TEST
238 #include <stdio.h>
239 #include <lzo/lzo1x.h>
240 #include "log.h"
241 #define MAXSZ (10*1024*1024)
242 int main(int argc, char *argv[]) {
243 FILE *in = fopen(argv[1], "rb");
244 uint8_t *orig = av_malloc(MAXSZ + 16);
245 uint8_t *comp = av_malloc(2*MAXSZ + 16);
246 uint8_t *decomp = av_malloc(MAXSZ + 16);
247 size_t s = fread(orig, 1, MAXSZ, in);
248 lzo_uint clen = 0;
249 long tmp[LZO1X_MEM_COMPRESS];
250 int inlen, outlen;
251 int i;
252 av_log_level = AV_LOG_DEBUG;
253 lzo1x_999_compress(orig, s, comp, &clen, tmp);
254 for (i = 0; i < 300; i++) {
255 START_TIMER
256 inlen = clen; outlen = MAXSZ;
257 #ifdef LIBLZO
258 if (lzo1x_decompress_safe(comp, inlen, decomp, &outlen, NULL))
259 #elif defined(LIBLZO_UNSAFE)
260 if (lzo1x_decompress(comp, inlen, decomp, &outlen, NULL))
261 #else
262 if (lzo1x_decode(decomp, &outlen, comp, &inlen))
263 #endif
264 av_log(NULL, AV_LOG_ERROR, "decompression error\n");
265 STOP_TIMER("lzod")
266 }
267 if (memcmp(orig, decomp, s))
268 av_log(NULL, AV_LOG_ERROR, "decompression incorrect\n");
269 else
270 av_log(NULL, AV_LOG_ERROR, "decompression ok\n");
271 return 0;
272 }
273 #endif