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, see <http://www.gnu.org/licenses/>.
29  */
30 
31 #include "decompress.h"
32 
read_int(unsigned char * ptr,int size)33 static long long INIT read_int(unsigned char *ptr, int size)
34 {
35 	int i;
36 	long long ret = 0;
37 
38 	for (i = 0; i < size; i++)
39 		ret = (ret << 8) | ptr[size-i-1];
40 	return ret;
41 }
42 
43 #define ENDIAN_CONVERT(x) \
44   x = (typeof(x))read_int((unsigned char *)&x, sizeof(x))
45 
46 
47 /* Small range coder implementation for lzma.
48  * Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
49  *
50  * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
51  * Copyright (c) 1999-2005  Igor Pavlov
52  */
53 
54 #ifdef __XEN__
55 #include <xen/compiler.h>
56 #include <xen/kernel.h>
57 #endif
58 
59 #define LZMA_IOBUF_SIZE	0x10000
60 
61 struct rc {
62 	int (*fill)(void*, unsigned int);
63 	uint8_t *ptr;
64 	uint8_t *buffer;
65 	uint8_t *buffer_end;
66 	int buffer_size;
67 	uint32_t code;
68 	uint32_t range;
69 	uint32_t bound;
70 	void (*error)(const char *);
71 };
72 
73 
74 #define RC_TOP_BITS 24
75 #define RC_MOVE_BITS 5
76 #define RC_MODEL_TOTAL_BITS 11
77 
78 
nofill(void * buffer,unsigned int len)79 static int INIT nofill(void *buffer, unsigned int len)
80 {
81 	return -1;
82 }
83 
84 /* Called twice: once at startup and once in rc_normalize() */
rc_read(struct rc * rc)85 static void INIT rc_read(struct rc *rc)
86 {
87 	rc->buffer_size = rc->fill((char *)rc->buffer, LZMA_IOBUF_SIZE);
88 	if (rc->buffer_size <= 0)
89 		rc->error("unexpected EOF");
90 	rc->ptr = rc->buffer;
91 	rc->buffer_end = rc->buffer + rc->buffer_size;
92 }
93 
94 /* Called once */
rc_init(struct rc * rc,int (* fill)(void *,unsigned int),unsigned char * buffer,int buffer_size)95 static inline void INIT rc_init(struct rc *rc,
96 				       int (*fill)(void*, unsigned int),
97 				       unsigned char *buffer, int buffer_size)
98 {
99 	if (fill)
100 		rc->fill = fill;
101 	else
102 		rc->fill = nofill;
103 	rc->buffer = (uint8_t *)buffer;
104 	rc->buffer_size = buffer_size;
105 	rc->buffer_end = rc->buffer + rc->buffer_size;
106 	rc->ptr = rc->buffer;
107 
108 	rc->code = 0;
109 	rc->range = 0xFFFFFFFF;
110 }
111 
rc_init_code(struct rc * rc)112 static inline void INIT rc_init_code(struct rc *rc)
113 {
114 	int i;
115 
116 	for (i = 0; i < 5; i++) {
117 		if (rc->ptr >= rc->buffer_end)
118 			rc_read(rc);
119 		rc->code = (rc->code << 8) | *rc->ptr++;
120 	}
121 }
122 
123 
124 /* Called twice, but one callsite is in inline'd rc_is_bit_0_helper() */
rc_do_normalize(struct rc * rc)125 static void INIT rc_do_normalize(struct rc *rc)
126 {
127 	if (rc->ptr >= rc->buffer_end)
128 		rc_read(rc);
129 	rc->range <<= 8;
130 	rc->code = (rc->code << 8) | *rc->ptr++;
131 }
rc_normalize(struct rc * rc)132 static inline void INIT rc_normalize(struct rc *rc)
133 {
134 	if (rc->range < (1 << RC_TOP_BITS))
135 		rc_do_normalize(rc);
136 }
137 
138 /* Called 9 times */
139 /* Why rc_is_bit_0_helper exists?
140  *Because we want to always expose (rc->code < rc->bound) to optimizer
141  */
rc_is_bit_0_helper(struct rc * rc,uint16_t * p)142 static inline uint32_t INIT rc_is_bit_0_helper(struct rc *rc, uint16_t *p)
143 {
144 	rc_normalize(rc);
145 	rc->bound = *p * (rc->range >> RC_MODEL_TOTAL_BITS);
146 	return rc->bound;
147 }
rc_is_bit_0(struct rc * rc,uint16_t * p)148 static inline int INIT rc_is_bit_0(struct rc *rc, uint16_t *p)
149 {
150 	uint32_t t = rc_is_bit_0_helper(rc, p);
151 	return rc->code < t;
152 }
153 
154 /* Called ~10 times, but very small, thus inlined */
rc_update_bit_0(struct rc * rc,uint16_t * p)155 static inline void INIT rc_update_bit_0(struct rc *rc, uint16_t *p)
156 {
157 	rc->range = rc->bound;
158 	*p += ((1 << RC_MODEL_TOTAL_BITS) - *p) >> RC_MOVE_BITS;
159 }
rc_update_bit_1(struct rc * rc,uint16_t * p)160 static inline void rc_update_bit_1(struct rc *rc, uint16_t *p)
161 {
162 	rc->range -= rc->bound;
163 	rc->code -= rc->bound;
164 	*p -= *p >> RC_MOVE_BITS;
165 }
166 
167 /* Called 4 times in unlzma loop */
rc_get_bit(struct rc * rc,uint16_t * p,int * symbol)168 static int INIT rc_get_bit(struct rc *rc, uint16_t *p, int *symbol)
169 {
170 	if (rc_is_bit_0(rc, p)) {
171 		rc_update_bit_0(rc, p);
172 		*symbol *= 2;
173 		return 0;
174 	} else {
175 		rc_update_bit_1(rc, p);
176 		*symbol = *symbol * 2 + 1;
177 		return 1;
178 	}
179 }
180 
181 /* Called once */
rc_direct_bit(struct rc * rc)182 static inline int INIT rc_direct_bit(struct rc *rc)
183 {
184 	rc_normalize(rc);
185 	rc->range >>= 1;
186 	if (rc->code >= rc->range) {
187 		rc->code -= rc->range;
188 		return 1;
189 	}
190 	return 0;
191 }
192 
193 /* Called twice */
194 static inline void INIT
rc_bit_tree_decode(struct rc * rc,uint16_t * p,int num_levels,int * symbol)195 rc_bit_tree_decode(struct rc *rc, uint16_t *p, int num_levels, int *symbol)
196 {
197 	int i = num_levels;
198 
199 	*symbol = 1;
200 	while (i--)
201 		rc_get_bit(rc, p + *symbol, symbol);
202 	*symbol -= 1 << num_levels;
203 }
204 
205 
206 /*
207  * Small lzma deflate implementation.
208  * Copyright (C) 2006  Aurelien Jacobs < aurel@gnuage.org >
209  *
210  * Based on LzmaDecode.c from the LZMA SDK 4.22 (http://www.7-zip.org/)
211  * Copyright (C) 1999-2005  Igor Pavlov
212  */
213 
214 
215 struct lzma_header {
216 	uint8_t pos;
217 	uint32_t dict_size;
218 	uint64_t dst_size;
219 } __attribute__((packed)) ;
220 
221 
222 #define LZMA_BASE_SIZE 1846
223 #define LZMA_LIT_SIZE 768
224 
225 #define LZMA_NUM_POS_BITS_MAX 4
226 
227 #define LZMA_LEN_NUM_LOW_BITS 3
228 #define LZMA_LEN_NUM_MID_BITS 3
229 #define LZMA_LEN_NUM_HIGH_BITS 8
230 
231 #define LZMA_LEN_CHOICE 0
232 #define LZMA_LEN_CHOICE_2 (LZMA_LEN_CHOICE + 1)
233 #define LZMA_LEN_LOW (LZMA_LEN_CHOICE_2 + 1)
234 #define LZMA_LEN_MID (LZMA_LEN_LOW \
235 		      + (1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_LOW_BITS)))
236 #define LZMA_LEN_HIGH (LZMA_LEN_MID \
237 		       +(1 << (LZMA_NUM_POS_BITS_MAX + LZMA_LEN_NUM_MID_BITS)))
238 #define LZMA_NUM_LEN_PROBS (LZMA_LEN_HIGH + (1 << LZMA_LEN_NUM_HIGH_BITS))
239 
240 #define LZMA_NUM_STATES 12
241 #define LZMA_NUM_LIT_STATES 7
242 
243 #define LZMA_START_POS_MODEL_INDEX 4
244 #define LZMA_END_POS_MODEL_INDEX 14
245 #define LZMA_NUM_FULL_DISTANCES (1 << (LZMA_END_POS_MODEL_INDEX >> 1))
246 
247 #define LZMA_NUM_POS_SLOT_BITS 6
248 #define LZMA_NUM_LEN_TO_POS_STATES 4
249 
250 #define LZMA_NUM_ALIGN_BITS 4
251 
252 #define LZMA_MATCH_MIN_LEN 2
253 
254 #define LZMA_IS_MATCH 0
255 #define LZMA_IS_REP (LZMA_IS_MATCH + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX))
256 #define LZMA_IS_REP_G0 (LZMA_IS_REP + LZMA_NUM_STATES)
257 #define LZMA_IS_REP_G1 (LZMA_IS_REP_G0 + LZMA_NUM_STATES)
258 #define LZMA_IS_REP_G2 (LZMA_IS_REP_G1 + LZMA_NUM_STATES)
259 #define LZMA_IS_REP_0_LONG (LZMA_IS_REP_G2 + LZMA_NUM_STATES)
260 #define LZMA_POS_SLOT (LZMA_IS_REP_0_LONG \
261 		       + (LZMA_NUM_STATES << LZMA_NUM_POS_BITS_MAX))
262 #define LZMA_SPEC_POS (LZMA_POS_SLOT \
263 		       +(LZMA_NUM_LEN_TO_POS_STATES << LZMA_NUM_POS_SLOT_BITS))
264 #define LZMA_ALIGN (LZMA_SPEC_POS \
265 		    + LZMA_NUM_FULL_DISTANCES - LZMA_END_POS_MODEL_INDEX)
266 #define LZMA_LEN_CODER (LZMA_ALIGN + (1 << LZMA_NUM_ALIGN_BITS))
267 #define LZMA_REP_LEN_CODER (LZMA_LEN_CODER + LZMA_NUM_LEN_PROBS)
268 #define LZMA_LITERAL (LZMA_REP_LEN_CODER + LZMA_NUM_LEN_PROBS)
269 
270 
271 struct writer {
272 	uint8_t *buffer;
273 	uint8_t previous_byte;
274 	size_t buffer_pos;
275 	int bufsize;
276 	size_t global_pos;
277 	int(*flush)(void*, unsigned int);
278 	struct lzma_header *header;
279 };
280 
281 struct cstate {
282 	int state;
283 	uint32_t rep0, rep1, rep2, rep3;
284 };
285 
get_pos(struct writer * wr)286 static inline size_t INIT get_pos(struct writer *wr)
287 {
288 	return
289 		wr->global_pos + wr->buffer_pos;
290 }
291 
peek_old_byte(struct writer * wr,uint32_t offs)292 static inline uint8_t INIT peek_old_byte(struct writer *wr,
293 						uint32_t offs)
294 {
295 	if (!wr->flush) {
296 		int32_t pos;
297 		while (offs > wr->header->dict_size)
298 			offs -= wr->header->dict_size;
299 		pos = wr->buffer_pos - offs;
300 		return wr->buffer[pos];
301 	} else {
302 		uint32_t pos = wr->buffer_pos - offs;
303 		while (pos >= wr->header->dict_size)
304 			pos += wr->header->dict_size;
305 		return wr->buffer[pos];
306 	}
307 
308 }
309 
write_byte(struct writer * wr,uint8_t byte)310 static inline int INIT write_byte(struct writer *wr, uint8_t byte)
311 {
312 	wr->buffer[wr->buffer_pos++] = wr->previous_byte = byte;
313 	if (wr->flush && wr->buffer_pos == wr->header->dict_size) {
314 		wr->buffer_pos = 0;
315 		wr->global_pos += wr->header->dict_size;
316 		if (wr->flush((char *)wr->buffer, wr->header->dict_size)
317 				!= wr->header->dict_size)
318 			return -1;
319 	}
320 	return 0;
321 }
322 
323 
copy_byte(struct writer * wr,uint32_t offs)324 static inline int INIT copy_byte(struct writer *wr, uint32_t offs)
325 {
326 	return write_byte(wr, peek_old_byte(wr, offs));
327 }
328 
copy_bytes(struct writer * wr,uint32_t rep0,int len)329 static inline int INIT copy_bytes(struct writer *wr,
330 					 uint32_t rep0, int len)
331 {
332 	do {
333 		if (copy_byte(wr, rep0))
334 			return -1;
335 		len--;
336 	} while (len != 0 && wr->buffer_pos < wr->header->dst_size);
337 
338 	return len;
339 }
340 
process_bit0(struct writer * wr,struct rc * rc,struct cstate * cst,uint16_t * p,int pos_state,uint16_t * prob,int lc,uint32_t literal_pos_mask)341 static inline int 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 	if (cst->state < 4)
376 		cst->state = 0;
377 	else if (cst->state < 10)
378 		cst->state -= 3;
379 	else
380 		cst->state -= 6;
381 
382 	return write_byte(wr, mi);
383 }
384 
process_bit1(struct writer * wr,struct rc * rc,struct cstate * cst,uint16_t * p,int pos_state,uint16_t * prob)385 static inline int INIT process_bit1(struct writer *wr, struct rc *rc,
386 					    struct cstate *cst, uint16_t *p,
387 					    int pos_state, uint16_t *prob) {
388   int offset;
389 	uint16_t *prob_len;
390 	int num_bits;
391 	int len;
392 
393 	rc_update_bit_1(rc, prob);
394 	prob = p + LZMA_IS_REP + cst->state;
395 	if (rc_is_bit_0(rc, prob)) {
396 		rc_update_bit_0(rc, prob);
397 		cst->rep3 = cst->rep2;
398 		cst->rep2 = cst->rep1;
399 		cst->rep1 = cst->rep0;
400 		cst->state = cst->state < LZMA_NUM_LIT_STATES ? 0 : 3;
401 		prob = p + LZMA_LEN_CODER;
402 	} else {
403 		rc_update_bit_1(rc, prob);
404 		prob = p + LZMA_IS_REP_G0 + cst->state;
405 		if (rc_is_bit_0(rc, prob)) {
406 			rc_update_bit_0(rc, prob);
407 			prob = (p + LZMA_IS_REP_0_LONG
408 				+ (cst->state <<
409 				   LZMA_NUM_POS_BITS_MAX) +
410 				pos_state);
411 			if (rc_is_bit_0(rc, prob)) {
412 				rc_update_bit_0(rc, prob);
413 
414 				cst->state = cst->state < LZMA_NUM_LIT_STATES ?
415 					9 : 11;
416 				return copy_byte(wr, cst->rep0);
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 0;
519 		if (cst->rep0 > wr->header->dict_size
520 				|| cst->rep0 > get_pos(wr))
521 			return -1;
522 	}
523 
524 	len += LZMA_MATCH_MIN_LEN;
525 
526 	return copy_bytes(wr, cst->rep0, len);
527 }
528 
529 
530 
unlzma(unsigned char * buf,unsigned int in_len,int (* fill)(void *,unsigned int),int (* flush)(void *,unsigned int),unsigned char * output,unsigned int * posp,void (* error)(const char * x))531 STATIC int INIT unlzma(unsigned char *buf, unsigned int in_len,
532 		       int(*fill)(void*, unsigned int),
533 		       int(*flush)(void*, unsigned int),
534 		       unsigned char *output,
535 		       unsigned int *posp,
536 		       void(*error)(const char *x)
537 	)
538 {
539 	struct lzma_header header;
540 	int lc, pb, lp;
541 	uint32_t pos_state_mask;
542 	uint32_t literal_pos_mask;
543 	uint16_t *p;
544 	int num_probs;
545 	struct rc rc;
546 	int i, mi;
547 	struct writer wr;
548 	struct cstate cst;
549 	unsigned char *inbuf;
550 	int ret = -1;
551 
552 	rc.error = error;
553 
554 	if (buf)
555 		inbuf = buf;
556 	else
557 		inbuf = malloc(LZMA_IOBUF_SIZE);
558 	if (!inbuf) {
559 		error("Could not allocate input buffer");
560 		goto exit_0;
561 	}
562 
563 	cst.state = 0;
564 	cst.rep0 = cst.rep1 = cst.rep2 = cst.rep3 = 1;
565 
566 	wr.header = &header;
567 	wr.flush = flush;
568 	wr.global_pos = 0;
569 	wr.previous_byte = 0;
570 	wr.buffer_pos = 0;
571 
572 	rc_init(&rc, fill, inbuf, in_len);
573 
574 	for (i = 0; i < sizeof(header); i++) {
575 		if (rc.ptr >= rc.buffer_end)
576 			rc_read(&rc);
577 		((unsigned char *)&header)[i] = *rc.ptr++;
578 	}
579 
580 	if (header.pos >= (9 * 5 * 5)) {
581 		error("bad header");
582 		goto exit_1;
583 	}
584 
585 	mi = 0;
586 	lc = header.pos;
587 	while (lc >= 9) {
588 		mi++;
589 		lc -= 9;
590 	}
591 	pb = 0;
592 	lp = mi;
593 	while (lp >= 5) {
594 		pb++;
595 		lp -= 5;
596 	}
597 	pos_state_mask = (1 << pb) - 1;
598 	literal_pos_mask = (1 << lp) - 1;
599 
600 	ENDIAN_CONVERT(header.dict_size);
601 	ENDIAN_CONVERT(header.dst_size);
602 
603 	if (header.dict_size == 0)
604 		header.dict_size = 1;
605 
606 	if (output)
607 		wr.buffer = output;
608 	else {
609 		wr.bufsize = MIN(header.dst_size, header.dict_size);
610 		wr.buffer = large_malloc(wr.bufsize);
611 	}
612 	if (wr.buffer == NULL)
613 		goto exit_1;
614 
615 	num_probs = LZMA_BASE_SIZE + (LZMA_LIT_SIZE << (lc + lp));
616 	p = (uint16_t *) large_malloc(num_probs * sizeof(*p));
617 	if (p == 0)
618 		goto exit_2;
619 	num_probs = LZMA_LITERAL + (LZMA_LIT_SIZE << (lc + lp));
620 	for (i = 0; i < num_probs; i++)
621 		p[i] = (1 << RC_MODEL_TOTAL_BITS) >> 1;
622 
623 	rc_init_code(&rc);
624 
625 	while (get_pos(&wr) < header.dst_size) {
626 		int pos_state =	get_pos(&wr) & pos_state_mask;
627 		uint16_t *prob = p + LZMA_IS_MATCH +
628 			(cst.state << LZMA_NUM_POS_BITS_MAX) + pos_state;
629 		if (rc_is_bit_0(&rc, prob)) {
630 			if (process_bit0(&wr, &rc, &cst, p, pos_state, prob,
631 					lc, literal_pos_mask)) {
632 				error("LZMA data is corrupt");
633 				goto exit_3;
634 			}
635 		} else {
636 			if (process_bit1(&wr, &rc, &cst, p, pos_state, prob)) {
637 				error("LZMA data is corrupt");
638 				goto exit_3;
639 			}
640 			if (cst.rep0 == 0)
641 				break;
642 		}
643 		if (rc.buffer_size <= 0)
644 			goto exit_3;
645 	}
646 
647 	if (posp)
648 		*posp = rc.ptr-rc.buffer;
649 	if (!wr.flush || wr.flush(wr.buffer, wr.buffer_pos) == wr.buffer_pos)
650 		ret = 0;
651 exit_3:
652 	large_free(p);
653 exit_2:
654 	if (!output)
655 		large_free(wr.buffer);
656 exit_1:
657 	if (!buf)
658 		free(inbuf);
659 exit_0:
660 	return ret;
661 }
662