Decompressors: fix header validation in decompress_unlzma.c
[linux-2.6.git] / lib / decompress_unlzma.c
1 /* Lzma decompressor for Linux kernel. Shamelessly snarfed
2  *from busybox 1.1.1
3  *
4  *Linux kernel adaptation
5  *Copyright (C) 2006  Alain < alain@knaff.lu >
6  *
7  *Based on small lzma deflate implementation/Small range coder
8  *implementation for lzma.
9  *Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
10  *
11  *Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
12  *Copyright (C) 1999-2005  Igor Pavlov
13  *
14  *Copyrights of the parts, see headers below.
15  *
16  *
17  *This program is free software; you can redistribute it and/or
18  *modify it under the terms of the GNU Lesser General Public
19  *License as published by the Free Software Foundation; either
20  *version 2.1 of the License, or (at your option) any later version.
21  *
22  *This program is distributed in the hope that it will be useful,
23  *but WITHOUT ANY WARRANTY; without even the implied warranty of
24  *MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
25  *Lesser General Public License for more details.
26  *
27  *You should have received a copy of the GNU Lesser General Public
28  *License along with this library; if not, write to the Free Software
29  *Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
30  */
31
32 #ifdef STATIC
33 #define PREBOOT
34 #else
35 #include <linux/decompress/unlzma.h>
36 #endif /* STATIC */
37
38 #include <linux/decompress/mm.h>
39
40 #define MIN(a, b) (((a) < (b)) ? (a) : (b))
41
42 static long long INIT read_int(unsigned char *ptr, int size)
43 {
44         int i;
45         long long ret = 0;
46
47         for (i = 0; i < size; i++)
48                 ret = (ret << 8) | ptr[size-i-1];
49         return ret;
50 }
51
52 #define ENDIAN_CONVERT(x) \
53   x = (typeof(x))read_int((unsigned char *)&x, sizeof(x))
54
55
56 /* Small range coder implementation for lzma.
57  *Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
58  *
59  *Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
60  *Copyright (c) 1999-2005  Igor Pavlov
61  */
62
63 #include <linux/compiler.h>
64
65 #define LZMA_IOBUF_SIZE 0x10000
66
67 struct rc {
68         int (*fill)(void*, unsigned int);
69         uint8_t *ptr;
70         uint8_t *buffer;
71         uint8_t *buffer_end;
72         int buffer_size;
73         uint32_t code;
74         uint32_t range;
75         uint32_t bound;
76         void (*error)(char *);
77 };
78
79
80 #define RC_TOP_BITS 24
81 #define RC_MOVE_BITS 5
82 #define RC_MODEL_TOTAL_BITS 11
83
84
85 static int INIT nofill(void *buffer, unsigned int len)
86 {
87         return -1;
88 }
89
90 /* Called twice: once at startup and once in rc_normalize() */
91 static void INIT rc_read(struct rc *rc)
92 {
93         rc->buffer_size = rc->fill((char *)rc->buffer, LZMA_IOBUF_SIZE);
94         if (rc->buffer_size <= 0)
95                 rc->error("unexpected EOF");
96         rc->ptr = rc->buffer;
97         rc->buffer_end = rc->buffer + rc->buffer_size;
98 }
99
100 /* Called once */
101 static inline void INIT rc_init(struct rc *rc,
102                                        int (*fill)(void*, unsigned int),
103                                        char *buffer, int buffer_size)
104 {
105         if (fill)
106                 rc->fill = fill;
107         else
108                 rc->fill = nofill;
109         rc->buffer = (uint8_t *)buffer;
110         rc->buffer_size = buffer_size;
111         rc->buffer_end = rc->buffer + rc->buffer_size;
112         rc->ptr = rc->buffer;
113
114         rc->code = 0;
115         rc->range = 0xFFFFFFFF;
116 }
117
118 static inline void INIT rc_init_code(struct rc *rc)
119 {
120         int i;
121
122         for (i = 0; i < 5; i++) {
123                 if (rc->ptr >= rc->buffer_end)
124                         rc_read(rc);
125                 rc->code = (rc->code << 8) | *rc->ptr++;
126         }
127 }
128
129
130 /* Called twice, but one callsite is in inline'd rc_is_bit_0_helper() */
131 static void INIT rc_do_normalize(struct rc *rc)
132 {
133         if (rc->ptr >= rc->buffer_end)
134                 rc_read(rc);
135         rc->range <<= 8;
136         rc->code = (rc->code << 8) | *rc->ptr++;
137 }
138 static inline void INIT rc_normalize(struct rc *rc)
139 {
140         if (rc->range < (1 << RC_TOP_BITS))
141                 rc_do_normalize(rc);
142 }
143
144 /* Called 9 times */
145 /* Why rc_is_bit_0_helper exists?
146  *Because we want to always expose (rc->code < rc->bound) to optimizer
147  */
148 static inline uint32_t INIT rc_is_bit_0_helper(struct rc *rc, uint16_t *p)
149 {
150         rc_normalize(rc);
151         rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
152         return rc->bound;
153 }
154 static inline int INIT rc_is_bit_0(struct rc *rc, uint16_t *p)
155 {
156         uint32_t t = rc_is_bit_0_helper(rc, p);
157         return rc->code < t;
158 }
159
160 /* Called ~10 times, but very small, thus inlined */
161 static inline void INIT rc_update_bit_0(struct rc *rc, uint16_t *p)
162 {
163         rc->range = rc->bound;
164         *p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
165 }
166 static inline void INIT rc_update_bit_1(struct rc *rc, uint16_t *p)
167 {
168         rc->range -= rc->bound;
169         rc->code -= rc->bound;
170         *p -= *p >> RC_MOVE_BITS;
171 }
172
173 /* Called 4 times in unlzma loop */
174 static int INIT rc_get_bit(struct rc *rc, uint16_t *p, int *symbol)
175 {
176         if (rc_is_bit_0(rc, p)) {
177                 rc_update_bit_0(rc, p);
178                 *symbol *= 2;
179                 return 0;
180         } else {
181                 rc_update_bit_1(rc, p);
182                 *symbol = *symbol * 2 + 1;
183                 return 1;
184         }
185 }
186
187 /* Called once */
188 static inline int INIT rc_direct_bit(struct rc *rc)
189 {
190         rc_normalize(rc);
191         rc->range >>= 1;
192         if (rc->code >= rc->range) {
193                 rc->code -= rc->range;
194                 return 1;
195         }
196         return 0;
197 }
198
199 /* Called twice */
200 static inline void INIT
201 rc_bit_tree_decode(struct rc *rc, uint16_t *p, int num_levels, int *symbol)
202 {
203         int i = num_levels;
204
205         *symbol = 1;
206         while (i--)
207                 rc_get_bit(rc, p + *symbol, symbol);
208         *symbol -= 1 << num_levels;
209 }
210
211
212 /*
213  * Small lzma deflate implementation.
214  * Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
215  *
216  * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
217  * Copyright (C) 1999-2005  Igor Pavlov
218  */
219
220
221 struct lzma_header {
222         uint8_t pos;
223         uint32_t dict_size;
224         uint64_t dst_size;
225 } __attribute__ ((packed)) ;
226
227
228 #define LZMA_BASE_SIZE 1846
229 #define LZMA_LIT_SIZE 768
230
231 #define LZMA_NUM_POS_BITS_MAX 4
232
233 #define LZMA_LEN_NUM_LOW_BITS 3
234 #define LZMA_LEN_NUM_MID_BITS 3
235 #define LZMA_LEN_NUM_HIGH_BITS 8
236
237 #define LZMA_LEN_CHOICE 0
238 #define LZMA_LEN_CHOICE_2 (LZMA_LEN_CHOICE + 1)
239 #define LZMA_LEN_LOW (LZMA_LEN_CHOICE_2 + 1)
240 #define LZMA_LEN_MID (LZMA_LEN_LOW \
241                       + (1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_LOW_BITS)))
242 #define LZMA_LEN_HIGH (LZMA_LEN_MID \
243                        +(1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_MID_BITS)))
244 #define LZMA_NUM_LEN_PROBS (LZMA_LEN_HIGH + (1 << LZMA_LEN_NUM_HIGH_BITS))
245
246 #define LZMA_NUM_STATES 12
247 #define LZMA_NUM_LIT_STATES 7
248
249 #define LZMA_START_POS_MODEL_INDEX 4
250 #define LZMA_END_POS_MODEL_INDEX 14
251 #define LZMA_NUM_FULL_DISTANCES (1 << (LZMA_END_POS_MODEL_INDEX >> 1))
252
253 #define LZMA_NUM_POS_SLOT_BITS 6
254 #define LZMA_NUM_LEN_TO_POS_STATES 4
255
256 #define LZMA_NUM_ALIGN_BITS 4
257
258 #define LZMA_MATCH_MIN_LEN 2
259
260 #define LZMA_IS_MATCH 0
261 #define LZMA_IS_REP (LZMA_IS_MATCH + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX))
262 #define LZMA_IS_REP_G0 (LZMA_IS_REP + LZMA_NUM_STATES)
263 #define LZMA_IS_REP_G1 (LZMA_IS_REP_G0 + LZMA_NUM_STATES)
264 #define LZMA_IS_REP_G2 (LZMA_IS_REP_G1 + LZMA_NUM_STATES)
265 #define LZMA_IS_REP_0_LONG (LZMA_IS_REP_G2 + LZMA_NUM_STATES)
266 #define LZMA_POS_SLOT (LZMA_IS_REP_0_LONG \
267                        + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX))
268 #define LZMA_SPEC_POS (LZMA_POS_SLOT \
269                        +(LZMA_NUM_LEN_TO_POS_STATES << LZMA_NUM_POS_SLOT_BITS))
270 #define LZMA_ALIGN (LZMA_SPEC_POS \
271                     + LZMA_NUM_FULL_DISTANCES - LZMA_END_POS_MODEL_INDEX)
272 #define LZMA_LEN_CODER (LZMA_ALIGN + (1 << LZMA_NUM_ALIGN_BITS))
273 #define LZMA_REP_LEN_CODER (LZMA_LEN_CODER + LZMA_NUM_LEN_PROBS)
274 #define LZMA_LITERAL (LZMA_REP_LEN_CODER + LZMA_NUM_LEN_PROBS)
275
276
277 struct writer {
278         uint8_t *buffer;
279         uint8_t previous_byte;
280         size_t buffer_pos;
281         int bufsize;
282         size_t global_pos;
283         int(*flush)(void*, unsigned int);
284         struct lzma_header *header;
285 };
286
287 struct cstate {
288         int state;
289         uint32_t rep0, rep1, rep2, rep3;
290 };
291
292 static inline size_t INIT get_pos(struct writer *wr)
293 {
294         return
295                 wr->global_pos + wr->buffer_pos;
296 }
297
298 static inline uint8_t INIT peek_old_byte(struct writer *wr,
299                                                 uint32_t offs)
300 {
301         if (!wr->flush) {
302                 int32_t pos;
303                 while (offs > wr->header->dict_size)
304                         offs -= wr->header->dict_size;
305                 pos = wr->buffer_pos - offs;
306                 return wr->buffer[pos];
307         } else {
308                 uint32_t pos = wr->buffer_pos - offs;
309                 while (pos >= wr->header->dict_size)
310                         pos += wr->header->dict_size;
311                 return wr->buffer[pos];
312         }
313
314 }
315
316 static inline void INIT write_byte(struct writer *wr, uint8_t byte)
317 {
318         wr->buffer[wr->buffer_pos++] = wr->previous_byte = byte;
319         if (wr->flush && wr->buffer_pos == wr->header->dict_size) {
320                 wr->buffer_pos = 0;
321                 wr->global_pos += wr->header->dict_size;
322                 wr->flush((char *)wr->buffer, wr->header->dict_size);
323         }
324 }
325
326
327 static inline void INIT copy_byte(struct writer *wr, uint32_t offs)
328 {
329         write_byte(wr, peek_old_byte(wr, offs));
330 }
331
332 static inline void INIT copy_bytes(struct writer *wr,
333                                          uint32_t rep0, int len)
334 {
335         do {
336                 copy_byte(wr, rep0);
337                 len--;
338         } while (len != 0 && wr->buffer_pos < wr->header->dst_size);
339 }
340
341 static inline void INIT process_bit0(struct writer *wr, struct rc *rc,
342                                      struct cstate *cst, uint16_t *p,
343                                      int pos_state, uint16_t *prob,
344                                      int lc, uint32_t literal_pos_mask) {
345         int mi = 1;
346         rc_update_bit_0(rc, prob);
347         prob = (p + LZMA_LITERAL +
348                 (LZMA_LIT_SIZE
349                  * (((get_pos(wr) & literal_pos_mask) << lc)
350                     + (wr->previous_byte >> (8 - lc))))
351                 );
352
353         if (cst->state >= LZMA_NUM_LIT_STATES) {
354                 int match_byte = peek_old_byte(wr, cst->rep0);
355                 do {
356                         int bit;
357                         uint16_t *prob_lit;
358
359                         match_byte <<= 1;
360                         bit = match_byte & 0x100;
361                         prob_lit = prob + 0x100 + bit + mi;
362                         if (rc_get_bit(rc, prob_lit, &mi)) {
363                                 if (!bit)
364                                         break;
365                         } else {
366                                 if (bit)
367                                         break;
368                         }
369                 } while (mi < 0x100);
370         }
371         while (mi < 0x100) {
372                 uint16_t *prob_lit = prob + mi;
373                 rc_get_bit(rc, prob_lit, &mi);
374         }
375         write_byte(wr, mi);
376         if (cst->state < 4)
377                 cst->state = 0;
378         else if (cst->state < 10)
379                 cst->state -= 3;
380         else
381                 cst->state -= 6;
382 }
383
384 static inline void INIT process_bit1(struct writer *wr, struct rc *rc,
385                                             struct cstate *cst, uint16_t *p,
386                                             int pos_state, uint16_t *prob) {
387   int offset;
388         uint16_t *prob_len;
389         int num_bits;
390         int len;
391
392         rc_update_bit_1(rc, prob);
393         prob = p + LZMA_IS_REP + cst->state;
394         if (rc_is_bit_0(rc, prob)) {
395                 rc_update_bit_0(rc, prob);
396                 cst->rep3 = cst->rep2;
397                 cst->rep2 = cst->rep1;
398                 cst->rep1 = cst->rep0;
399                 cst->state = cst->state < LZMA_NUM_LIT_STATES ? 0 : 3;
400                 prob = p + LZMA_LEN_CODER;
401         } else {
402                 rc_update_bit_1(rc, prob);
403                 prob = p + LZMA_IS_REP_G0 + cst->state;
404                 if (rc_is_bit_0(rc, prob)) {
405                         rc_update_bit_0(rc, prob);
406                         prob = (p + LZMA_IS_REP_0_LONG
407                                 + (cst->state <<
408                                    LZMA_NUM_POS_BITS_MAX) +
409                                 pos_state);
410                         if (rc_is_bit_0(rc, prob)) {
411                                 rc_update_bit_0(rc, prob);
412
413                                 cst->state = cst->state < LZMA_NUM_LIT_STATES ?
414                                         9 : 11;
415                                 copy_byte(wr, cst->rep0);
416                                 return;
417                         } else {
418                                 rc_update_bit_1(rc, prob);
419                         }
420                 } else {
421                         uint32_t distance;
422
423                         rc_update_bit_1(rc, prob);
424                         prob = p + LZMA_IS_REP_G1 + cst->state;
425                         if (rc_is_bit_0(rc, prob)) {
426                                 rc_update_bit_0(rc, prob);
427                                 distance = cst->rep1;
428                         } else {
429                                 rc_update_bit_1(rc, prob);
430                                 prob = p + LZMA_IS_REP_G2 + cst->state;
431                                 if (rc_is_bit_0(rc, prob)) {
432                                         rc_update_bit_0(rc, prob);
433                                         distance = cst->rep2;
434                                 } else {
435                                         rc_update_bit_1(rc, prob);
436                                         distance = cst->rep3;
437                                         cst->rep3 = cst->rep2;
438                                 }
439                                 cst->rep2 = cst->rep1;
440                         }
441                         cst->rep1 = cst->rep0;
442                         cst->rep0 = distance;
443                 }
444                 cst->state = cst->state < LZMA_NUM_LIT_STATES ? 8 : 11;
445                 prob = p + LZMA_REP_LEN_CODER;
446         }
447
448         prob_len = prob + LZMA_LEN_CHOICE;
449         if (rc_is_bit_0(rc, prob_len)) {
450                 rc_update_bit_0(rc, prob_len);
451                 prob_len = (prob + LZMA_LEN_LOW
452                             + (pos_state <<
453                                LZMA_LEN_NUM_LOW_BITS));
454                 offset = 0;
455                 num_bits = LZMA_LEN_NUM_LOW_BITS;
456         } else {
457                 rc_update_bit_1(rc, prob_len);
458                 prob_len = prob + LZMA_LEN_CHOICE_2;
459                 if (rc_is_bit_0(rc, prob_len)) {
460                         rc_update_bit_0(rc, prob_len);
461                         prob_len = (prob + LZMA_LEN_MID
462                                     + (pos_state <<
463                                        LZMA_LEN_NUM_MID_BITS));
464                         offset = 1 << LZMA_LEN_NUM_LOW_BITS;
465                         num_bits = LZMA_LEN_NUM_MID_BITS;
466                 } else {
467                         rc_update_bit_1(rc, prob_len);
468                         prob_len = prob + LZMA_LEN_HIGH;
469                         offset = ((1 << LZMA_LEN_NUM_LOW_BITS)
470                                   + (1 << LZMA_LEN_NUM_MID_BITS));
471                         num_bits = LZMA_LEN_NUM_HIGH_BITS;
472                 }
473         }
474
475         rc_bit_tree_decode(rc, prob_len, num_bits, &len);
476         len += offset;
477
478         if (cst->state < 4) {
479                 int pos_slot;
480
481                 cst->state += LZMA_NUM_LIT_STATES;
482                 prob =
483                         p + LZMA_POS_SLOT +
484                         ((len <
485                           LZMA_NUM_LEN_TO_POS_STATES ? len :
486                           LZMA_NUM_LEN_TO_POS_STATES - 1)
487                          << LZMA_NUM_POS_SLOT_BITS);
488                 rc_bit_tree_decode(rc, prob,
489                                    LZMA_NUM_POS_SLOT_BITS,
490                                    &pos_slot);
491                 if (pos_slot >= LZMA_START_POS_MODEL_INDEX) {
492                         int i, mi;
493                         num_bits = (pos_slot >> 1) - 1;
494                         cst->rep0 = 2 | (pos_slot & 1);
495                         if (pos_slot < LZMA_END_POS_MODEL_INDEX) {
496                                 cst->rep0 <<= num_bits;
497                                 prob = p + LZMA_SPEC_POS +
498                                         cst->rep0 - pos_slot - 1;
499                         } else {
500                                 num_bits -= LZMA_NUM_ALIGN_BITS;
501                                 while (num_bits--)
502                                         cst->rep0 = (cst->rep0 << 1) |
503                                                 rc_direct_bit(rc);
504                                 prob = p + LZMA_ALIGN;
505                                 cst->rep0 <<= LZMA_NUM_ALIGN_BITS;
506                                 num_bits = LZMA_NUM_ALIGN_BITS;
507                         }
508                         i = 1;
509                         mi = 1;
510                         while (num_bits--) {
511                                 if (rc_get_bit(rc, prob + mi, &mi))
512                                         cst->rep0 |= i;
513                                 i <<= 1;
514                         }
515                 } else
516                         cst->rep0 = pos_slot;
517                 if (++(cst->rep0) == 0)
518                         return;
519         }
520
521         len += LZMA_MATCH_MIN_LEN;
522
523         copy_bytes(wr, cst->rep0, len);
524 }
525
526
527
528 STATIC inline int INIT unlzma(unsigned char *buf, int in_len,
529                               int(*fill)(void*, unsigned int),
530                               int(*flush)(void*, unsigned int),
531                               unsigned char *output,
532                               int *posp,
533                               void(*error)(char *x)
534         )
535 {
536         struct lzma_header header;
537         int lc, pb, lp;
538         uint32_t pos_state_mask;
539         uint32_t literal_pos_mask;
540         uint16_t *p;
541         int num_probs;
542         struct rc rc;
543         int i, mi;
544         struct writer wr;
545         struct cstate cst;
546         unsigned char *inbuf;
547         int ret = -1;
548
549         rc.error = error;
550
551         if (buf)
552                 inbuf = buf;
553         else
554                 inbuf = malloc(LZMA_IOBUF_SIZE);
555         if (!inbuf) {
556                 error("Could not allocate input bufer");
557                 goto exit_0;
558         }
559
560         cst.state = 0;
561         cst.rep0 = cst.rep1 = cst.rep2 = cst.rep3 = 1;
562
563         wr.header = &header;
564         wr.flush = flush;
565         wr.global_pos = 0;
566         wr.previous_byte = 0;
567         wr.buffer_pos = 0;
568
569         rc_init(&rc, fill, inbuf, in_len);
570
571         for (i = 0; i < sizeof(header); i++) {
572                 if (rc.ptr >= rc.buffer_end)
573                         rc_read(&rc);
574                 ((unsigned char *)&header)[i] = *rc.ptr++;
575         }
576
577         if (header.pos >= (9 * 5 * 5)) {
578                 error("bad header");
579                 goto exit_1;
580         }
581
582         mi = 0;
583         lc = header.pos;
584         while (lc >= 9) {
585                 mi++;
586                 lc -= 9;
587         }
588         pb = 0;
589         lp = mi;
590         while (lp >= 5) {
591                 pb++;
592                 lp -= 5;
593         }
594         pos_state_mask = (1 << pb) - 1;
595         literal_pos_mask = (1 << lp) - 1;
596
597         ENDIAN_CONVERT(header.dict_size);
598         ENDIAN_CONVERT(header.dst_size);
599
600         if (header.dict_size == 0)
601                 header.dict_size = 1;
602
603         if (output)
604                 wr.buffer = output;
605         else {
606                 wr.bufsize = MIN(header.dst_size, header.dict_size);
607                 wr.buffer = large_malloc(wr.bufsize);
608         }
609         if (wr.buffer == NULL)
610                 goto exit_1;
611
612         num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
613         p = (uint16_t *) large_malloc(num_probs * sizeof(*p));
614         if (p == 0)
615                 goto exit_2;
616         num_probs = LZMA_LITERAL + (LZMA_LIT_SIZE << (lc + lp));
617         for (i = 0; i < num_probs; i++)
618                 p[i] = (1 << RC_MODEL_TOTAL_BITS) >> 1;
619
620         rc_init_code(&rc);
621
622         while (get_pos(&wr) < header.dst_size) {
623                 int pos_state = get_pos(&wr) & pos_state_mask;
624                 uint16_t *prob = p + LZMA_IS_MATCH +
625                         (cst.state << LZMA_NUM_POS_BITS_MAX) + pos_state;
626                 if (rc_is_bit_0(&rc, prob))
627                         process_bit0(&wr, &rc, &cst, p, pos_state, prob,
628                                      lc, literal_pos_mask);
629                 else {
630                         process_bit1(&wr, &rc, &cst, p, pos_state, prob);
631                         if (cst.rep0 == 0)
632                                 break;
633                 }
634         }
635
636         if (posp)
637                 *posp = rc.ptr-rc.buffer;
638         if (wr.flush)
639                 wr.flush(wr.buffer, wr.buffer_pos);
640         ret = 0;
641         large_free(p);
642 exit_2:
643         if (!output)
644                 large_free(wr.buffer);
645 exit_1:
646         if (!buf)
647                 free(inbuf);
648 exit_0:
649         return ret;
650 }
651
652 #ifdef PREBOOT
653 STATIC int INIT decompress(unsigned char *buf, int in_len,
654                               int(*fill)(void*, unsigned int),
655                               int(*flush)(void*, unsigned int),
656                               unsigned char *output,
657                               int *posp,
658                               void(*error)(char *x)
659         )
660 {
661         return unlzma(buf, in_len - 4, fill, flush, output, posp, error);
662 }
663 #endif