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Linux/lib/decompress_unlzo.c

  1 /*
  2  * LZO decompressor for the Linux kernel. Code borrowed from the lzo
  3  * implementation by Markus Franz Xaver Johannes Oberhumer.
  4  *
  5  * Linux kernel adaptation:
  6  * Copyright (C) 2009
  7  * Albin Tonnerre, Free Electrons <albin.tonnerre@free-electrons.com>
  8  *
  9  * Original code:
 10  * Copyright (C) 1996-2005 Markus Franz Xaver Johannes Oberhumer
 11  * All Rights Reserved.
 12  *
 13  * lzop and the LZO library are free software; you can redistribute them
 14  * and/or modify them under the terms of the GNU General Public License as
 15  * published by the Free Software Foundation; either version 2 of
 16  * the License, or (at your option) any later version.
 17  *
 18  * This program is distributed in the hope that it will be useful,
 19  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 20  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 21  * GNU General Public License for more details.
 22  *
 23  * You should have received a copy of the GNU General Public License
 24  * along with this program; see the file COPYING.
 25  * If not, write to the Free Software Foundation, Inc.,
 26  * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 27  *
 28  * Markus F.X.J. Oberhumer
 29  * <markus@oberhumer.com>
 30  * http://www.oberhumer.com/opensource/lzop/
 31  */
 32 
 33 #ifdef STATIC
 34 #define PREBOOT
 35 #include "lzo/lzo1x_decompress_safe.c"
 36 #else
 37 #include <linux/decompress/unlzo.h>
 38 #endif
 39 
 40 #include <linux/types.h>
 41 #include <linux/lzo.h>
 42 #include <linux/decompress/mm.h>
 43 
 44 #include <linux/compiler.h>
 45 #include <asm/unaligned.h>
 46 
 47 static const unsigned char lzop_magic[] = {
 48         0x89, 0x4c, 0x5a, 0x4f, 0x00, 0x0d, 0x0a, 0x1a, 0x0a };
 49 
 50 #define LZO_BLOCK_SIZE        (256*1024l)
 51 #define HEADER_HAS_FILTER      0x00000800L
 52 #define HEADER_SIZE_MIN       (9 + 7     + 4 + 8     + 1       + 4)
 53 #define HEADER_SIZE_MAX       (9 + 7 + 1 + 8 + 8 + 4 + 1 + 255 + 4)
 54 
 55 STATIC inline long INIT parse_header(u8 *input, long *skip, long in_len)
 56 {
 57         int l;
 58         u8 *parse = input;
 59         u8 *end = input + in_len;
 60         u8 level = 0;
 61         u16 version;
 62 
 63         /*
 64          * Check that there's enough input to possibly have a valid header.
 65          * Then it is possible to parse several fields until the minimum
 66          * size may have been used.
 67          */
 68         if (in_len < HEADER_SIZE_MIN)
 69                 return 0;
 70 
 71         /* read magic: 9 first bits */
 72         for (l = 0; l < 9; l++) {
 73                 if (*parse++ != lzop_magic[l])
 74                         return 0;
 75         }
 76         /* get version (2bytes), skip library version (2),
 77          * 'need to be extracted' version (2) and
 78          * method (1) */
 79         version = get_unaligned_be16(parse);
 80         parse += 7;
 81         if (version >= 0x0940)
 82                 level = *parse++;
 83         if (get_unaligned_be32(parse) & HEADER_HAS_FILTER)
 84                 parse += 8; /* flags + filter info */
 85         else
 86                 parse += 4; /* flags */
 87 
 88         /*
 89          * At least mode, mtime_low, filename length, and checksum must
 90          * be left to be parsed. If also mtime_high is present, it's OK
 91          * because the next input buffer check is after reading the
 92          * filename length.
 93          */
 94         if (end - parse < 8 + 1 + 4)
 95                 return 0;
 96 
 97         /* skip mode and mtime_low */
 98         parse += 8;
 99         if (version >= 0x0940)
100                 parse += 4;     /* skip mtime_high */
101 
102         l = *parse++;
103         /* don't care about the file name, and skip checksum */
104         if (end - parse < l + 4)
105                 return 0;
106         parse += l + 4;
107 
108         *skip = parse - input;
109         return 1;
110 }
111 
112 STATIC int INIT unlzo(u8 *input, long in_len,
113                                 long (*fill)(void *, unsigned long),
114                                 long (*flush)(void *, unsigned long),
115                                 u8 *output, long *posp,
116                                 void (*error) (char *x))
117 {
118         u8 r = 0;
119         long skip = 0;
120         u32 src_len, dst_len;
121         size_t tmp;
122         u8 *in_buf, *in_buf_save, *out_buf;
123         int ret = -1;
124 
125         if (output) {
126                 out_buf = output;
127         } else if (!flush) {
128                 error("NULL output pointer and no flush function provided");
129                 goto exit;
130         } else {
131                 out_buf = malloc(LZO_BLOCK_SIZE);
132                 if (!out_buf) {
133                         error("Could not allocate output buffer");
134                         goto exit;
135                 }
136         }
137 
138         if (input && fill) {
139                 error("Both input pointer and fill function provided, don't know what to do");
140                 goto exit_1;
141         } else if (input) {
142                 in_buf = input;
143         } else if (!fill) {
144                 error("NULL input pointer and missing fill function");
145                 goto exit_1;
146         } else {
147                 in_buf = malloc(lzo1x_worst_compress(LZO_BLOCK_SIZE));
148                 if (!in_buf) {
149                         error("Could not allocate input buffer");
150                         goto exit_1;
151                 }
152         }
153         in_buf_save = in_buf;
154 
155         if (posp)
156                 *posp = 0;
157 
158         if (fill) {
159                 /*
160                  * Start from in_buf + HEADER_SIZE_MAX to make it possible
161                  * to use memcpy() to copy the unused data to the beginning
162                  * of the buffer. This way memmove() isn't needed which
163                  * is missing from pre-boot environments of most archs.
164                  */
165                 in_buf += HEADER_SIZE_MAX;
166                 in_len = fill(in_buf, HEADER_SIZE_MAX);
167         }
168 
169         if (!parse_header(in_buf, &skip, in_len)) {
170                 error("invalid header");
171                 goto exit_2;
172         }
173         in_buf += skip;
174         in_len -= skip;
175 
176         if (fill) {
177                 /* Move the unused data to the beginning of the buffer. */
178                 memcpy(in_buf_save, in_buf, in_len);
179                 in_buf = in_buf_save;
180         }
181 
182         if (posp)
183                 *posp = skip;
184 
185         for (;;) {
186                 /* read uncompressed block size */
187                 if (fill && in_len < 4) {
188                         skip = fill(in_buf + in_len, 4 - in_len);
189                         if (skip > 0)
190                                 in_len += skip;
191                 }
192                 if (in_len < 4) {
193                         error("file corrupted");
194                         goto exit_2;
195                 }
196                 dst_len = get_unaligned_be32(in_buf);
197                 in_buf += 4;
198                 in_len -= 4;
199 
200                 /* exit if last block */
201                 if (dst_len == 0) {
202                         if (posp)
203                                 *posp += 4;
204                         break;
205                 }
206 
207                 if (dst_len > LZO_BLOCK_SIZE) {
208                         error("dest len longer than block size");
209                         goto exit_2;
210                 }
211 
212                 /* read compressed block size, and skip block checksum info */
213                 if (fill && in_len < 8) {
214                         skip = fill(in_buf + in_len, 8 - in_len);
215                         if (skip > 0)
216                                 in_len += skip;
217                 }
218                 if (in_len < 8) {
219                         error("file corrupted");
220                         goto exit_2;
221                 }
222                 src_len = get_unaligned_be32(in_buf);
223                 in_buf += 8;
224                 in_len -= 8;
225 
226                 if (src_len <= 0 || src_len > dst_len) {
227                         error("file corrupted");
228                         goto exit_2;
229                 }
230 
231                 /* decompress */
232                 if (fill && in_len < src_len) {
233                         skip = fill(in_buf + in_len, src_len - in_len);
234                         if (skip > 0)
235                                 in_len += skip;
236                 }
237                 if (in_len < src_len) {
238                         error("file corrupted");
239                         goto exit_2;
240                 }
241                 tmp = dst_len;
242 
243                 /* When the input data is not compressed at all,
244                  * lzo1x_decompress_safe will fail, so call memcpy()
245                  * instead */
246                 if (unlikely(dst_len == src_len))
247                         memcpy(out_buf, in_buf, src_len);
248                 else {
249                         r = lzo1x_decompress_safe((u8 *) in_buf, src_len,
250                                                 out_buf, &tmp);
251 
252                         if (r != LZO_E_OK || dst_len != tmp) {
253                                 error("Compressed data violation");
254                                 goto exit_2;
255                         }
256                 }
257 
258                 if (flush && flush(out_buf, dst_len) != dst_len)
259                         goto exit_2;
260                 if (output)
261                         out_buf += dst_len;
262                 if (posp)
263                         *posp += src_len + 12;
264 
265                 in_buf += src_len;
266                 in_len -= src_len;
267                 if (fill) {
268                         /*
269                          * If there happens to still be unused data left in
270                          * in_buf, move it to the beginning of the buffer.
271                          * Use a loop to avoid memmove() dependency.
272                          */
273                         if (in_len > 0)
274                                 for (skip = 0; skip < in_len; ++skip)
275                                         in_buf_save[skip] = in_buf[skip];
276                         in_buf = in_buf_save;
277                 }
278         }
279 
280         ret = 0;
281 exit_2:
282         if (!input)
283                 free(in_buf_save);
284 exit_1:
285         if (!output)
286                 free(out_buf);
287 exit:
288         return ret;
289 }
290 
291 #ifdef PREBOOT
292 STATIC int INIT __decompress(unsigned char *buf, long len,
293                            long (*fill)(void*, unsigned long),
294                            long (*flush)(void*, unsigned long),
295                            unsigned char *out_buf, long olen,
296                            long *pos,
297                            void (*error)(char *x))
298 {
299         return unlzo(buf, len, fill, flush, out_buf, pos, error);
300 }
301 #endif
302 

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