1/* Small bzip2 deflate implementation, by Rob Landley (rob@landley.net).
2
3 Based on bzip2 decompression code by Julian R Seward (jseward@acm.org),
4 which also acknowledges contributions by Mike Burrows, David Wheeler,
5 Peter Fenwick, Alistair Moffat, Radford Neal, Ian H. Witten,
6 Robert Sedgewick, and Jon L. Bentley.
7
8 This code is licensed under the LGPLv2:
9 LGPL (http://www.gnu.org/copyleft/lgpl.html
10*/
11
12/*
13 Size and speed optimizations by Manuel Novoa III (mjn3@codepoet.org).
14
15 More efficient reading of Huffman codes, a streamlined read_bunzip()
16 function, and various other tweaks. In (limited) tests, approximately
17 20% faster than bzcat on x86 and about 10% faster on arm.
18
19 Note that about 2/3 of the time is spent in read_unzip() reversing
20 the Burrows-Wheeler transformation. Much of that time is delay
21 resulting from cache misses.
22
23 I would ask that anyone benefiting from this work, especially those
24 using it in commercial products, consider making a donation to my local
25 non-profit hospice organization in the name of the woman I loved, who
26 passed away Feb. 12, 2003.
27
28 In memory of Toni W. Hagan
29
30 Hospice of Acadiana, Inc.
31 2600 Johnston St., Suite 200
32 Lafayette, LA 70503-3240
33
34 Phone (337) 232-1234 or 1-800-738-2226
35 Fax (337) 232-1297
36
37 http://www.hospiceacadiana.com/
38
39 Manuel
40 */
41
42/*
43 Made it fit for running in Linux Kernel by Alain Knaff (alain@knaff.lu)
44*/
45
46
47#ifdef STATIC
48#define PREBOOT
49#else
50#include <linux/decompress/bunzip2.h>
51#endif /* STATIC */
52
53#include <linux/decompress/mm.h>
54#include <linux/crc32poly.h>
55
56#ifndef INT_MAX
57#define INT_MAX 0x7fffffff
58#endif
59
60/* Constants for Huffman coding */
61#define MAX_GROUPS 6
62#define GROUP_SIZE 50 /* 64 would have been more efficient */
63#define MAX_HUFCODE_BITS 20 /* Longest Huffman code allowed */
64#define MAX_SYMBOLS 258 /* 256 literals + RUNA + RUNB */
65#define SYMBOL_RUNA 0
66#define SYMBOL_RUNB 1
67
68/* Status return values */
69#define RETVAL_OK 0
70#define RETVAL_LAST_BLOCK (-1)
71#define RETVAL_NOT_BZIP_DATA (-2)
72#define RETVAL_UNEXPECTED_INPUT_EOF (-3)
73#define RETVAL_UNEXPECTED_OUTPUT_EOF (-4)
74#define RETVAL_DATA_ERROR (-5)
75#define RETVAL_OUT_OF_MEMORY (-6)
76#define RETVAL_OBSOLETE_INPUT (-7)
77
78/* Other housekeeping constants */
79#define BZIP2_IOBUF_SIZE 4096
80
81/* This is what we know about each Huffman coding group */
82struct group_data {
83 /* We have an extra slot at the end of limit[] for a sentinal value. */
84 int limit[MAX_HUFCODE_BITS+1];
85 int base[MAX_HUFCODE_BITS];
86 int permute[MAX_SYMBOLS];
87 int minLen, maxLen;
88};
89
90/* Structure holding all the housekeeping data, including IO buffers and
91 memory that persists between calls to bunzip */
92struct bunzip_data {
93 /* State for interrupting output loop */
94 int writeCopies, writePos, writeRunCountdown, writeCount, writeCurrent;
95 /* I/O tracking data (file handles, buffers, positions, etc.) */
96 long (*fill)(void*, unsigned long);
97 long inbufCount, inbufPos /*, outbufPos*/;
98 unsigned char *inbuf /*,*outbuf*/;
99 unsigned int inbufBitCount, inbufBits;
100 /* The CRC values stored in the block header and calculated from the
101 data */
102 unsigned int crc32Table[256], headerCRC, totalCRC, writeCRC;
103 /* Intermediate buffer and its size (in bytes) */
104 unsigned int *dbuf, dbufSize;
105 /* These things are a bit too big to go on the stack */
106 unsigned char selectors[32768]; /* nSelectors = 15 bits */
107 struct group_data groups[MAX_GROUPS]; /* Huffman coding tables */
108 int io_error; /* non-zero if we have IO error */
109 int byteCount[256];
110 unsigned char symToByte[256], mtfSymbol[256];
111};
112
113
114/* Return the next nnn bits of input. All reads from the compressed input
115 are done through this function. All reads are big endian */
116static unsigned int INIT get_bits(struct bunzip_data *bd, char bits_wanted)
117{
118 unsigned int bits = 0;
119
120 /* If we need to get more data from the byte buffer, do so.
121 (Loop getting one byte at a time to enforce endianness and avoid
122 unaligned access.) */
123 while (bd->inbufBitCount < bits_wanted) {
124 /* If we need to read more data from file into byte buffer, do
125 so */
126 if (bd->inbufPos == bd->inbufCount) {
127 if (bd->io_error)
128 return 0;
129 bd->inbufCount = bd->fill(bd->inbuf, BZIP2_IOBUF_SIZE);
130 if (bd->inbufCount <= 0) {
131 bd->io_error = RETVAL_UNEXPECTED_INPUT_EOF;
132 return 0;
133 }
134 bd->inbufPos = 0;
135 }
136 /* Avoid 32-bit overflow (dump bit buffer to top of output) */
137 if (bd->inbufBitCount >= 24) {
138 bits = bd->inbufBits&((1 << bd->inbufBitCount)-1);
139 bits_wanted -= bd->inbufBitCount;
140 bits <<= bits_wanted;
141 bd->inbufBitCount = 0;
142 }
143 /* Grab next 8 bits of input from buffer. */
144 bd->inbufBits = (bd->inbufBits << 8)|bd->inbuf[bd->inbufPos++];
145 bd->inbufBitCount += 8;
146 }
147 /* Calculate result */
148 bd->inbufBitCount -= bits_wanted;
149 bits |= (bd->inbufBits >> bd->inbufBitCount)&((1 << bits_wanted)-1);
150
151 return bits;
152}
153
154/* Unpacks the next block and sets up for the inverse burrows-wheeler step. */
155
156static int INIT get_next_block(struct bunzip_data *bd)
157{
158 struct group_data *hufGroup = NULL;
159 int *base = NULL;
160 int *limit = NULL;
161 int dbufCount, nextSym, dbufSize, groupCount, selector,
162 i, j, k, t, runPos, symCount, symTotal, nSelectors, *byteCount;
163 unsigned char uc, *symToByte, *mtfSymbol, *selectors;
164 unsigned int *dbuf, origPtr;
165
166 dbuf = bd->dbuf;
167 dbufSize = bd->dbufSize;
168 selectors = bd->selectors;
169 byteCount = bd->byteCount;
170 symToByte = bd->symToByte;
171 mtfSymbol = bd->mtfSymbol;
172
173 /* Read in header signature and CRC, then validate signature.
174 (last block signature means CRC is for whole file, return now) */
175 i = get_bits(bd, 24);
176 j = get_bits(bd, 24);
177 bd->headerCRC = get_bits(bd, 32);
178 if ((i == 0x177245) && (j == 0x385090))
179 return RETVAL_LAST_BLOCK;
180 if ((i != 0x314159) || (j != 0x265359))
181 return RETVAL_NOT_BZIP_DATA;
182 /* We can add support for blockRandomised if anybody complains.
183 There was some code for this in busybox 1.0.0-pre3, but nobody ever
184 noticed that it didn't actually work. */
185 if (get_bits(bd, 1))
186 return RETVAL_OBSOLETE_INPUT;
187 origPtr = get_bits(bd, 24);
188 if (origPtr >= dbufSize)
189 return RETVAL_DATA_ERROR;
190 /* mapping table: if some byte values are never used (encoding things
191 like ascii text), the compression code removes the gaps to have fewer
192 symbols to deal with, and writes a sparse bitfield indicating which
193 values were present. We make a translation table to convert the
194 symbols back to the corresponding bytes. */
195 t = get_bits(bd, 16);
196 symTotal = 0;
197 for (i = 0; i < 16; i++) {
198 if (t&(1 << (15-i))) {
199 k = get_bits(bd, 16);
200 for (j = 0; j < 16; j++)
201 if (k&(1 << (15-j)))
202 symToByte[symTotal++] = (16*i)+j;
203 }
204 }
205 /* How many different Huffman coding groups does this block use? */
206 groupCount = get_bits(bd, 3);
207 if (groupCount < 2 || groupCount > MAX_GROUPS)
208 return RETVAL_DATA_ERROR;
209 /* nSelectors: Every GROUP_SIZE many symbols we select a new
210 Huffman coding group. Read in the group selector list,
211 which is stored as MTF encoded bit runs. (MTF = Move To
212 Front, as each value is used it's moved to the start of the
213 list.) */
214 nSelectors = get_bits(bd, 15);
215 if (!nSelectors)
216 return RETVAL_DATA_ERROR;
217 for (i = 0; i < groupCount; i++)
218 mtfSymbol[i] = i;
219 for (i = 0; i < nSelectors; i++) {
220 /* Get next value */
221 for (j = 0; get_bits(bd, 1); j++)
222 if (j >= groupCount)
223 return RETVAL_DATA_ERROR;
224 /* Decode MTF to get the next selector */
225 uc = mtfSymbol[j];
226 for (; j; j--)
227 mtfSymbol[j] = mtfSymbol[j-1];
228 mtfSymbol[0] = selectors[i] = uc;
229 }
230 /* Read the Huffman coding tables for each group, which code
231 for symTotal literal symbols, plus two run symbols (RUNA,
232 RUNB) */
233 symCount = symTotal+2;
234 for (j = 0; j < groupCount; j++) {
235 unsigned char length[MAX_SYMBOLS], temp[MAX_HUFCODE_BITS+1];
236 int minLen, maxLen, pp;
237 /* Read Huffman code lengths for each symbol. They're
238 stored in a way similar to mtf; record a starting
239 value for the first symbol, and an offset from the
240 previous value for everys symbol after that.
241 (Subtracting 1 before the loop and then adding it
242 back at the end is an optimization that makes the
243 test inside the loop simpler: symbol length 0
244 becomes negative, so an unsigned inequality catches
245 it.) */
246 t = get_bits(bd, 5)-1;
247 for (i = 0; i < symCount; i++) {
248 for (;;) {
249 if (((unsigned)t) > (MAX_HUFCODE_BITS-1))
250 return RETVAL_DATA_ERROR;
251
252 /* If first bit is 0, stop. Else
253 second bit indicates whether to
254 increment or decrement the value.
255 Optimization: grab 2 bits and unget
256 the second if the first was 0. */
257
258 k = get_bits(bd, 2);
259 if (k < 2) {
260 bd->inbufBitCount++;
261 break;
262 }
263 /* Add one if second bit 1, else
264 * subtract 1. Avoids if/else */
265 t += (((k+1)&2)-1);
266 }
267 /* Correct for the initial -1, to get the
268 * final symbol length */
269 length[i] = t+1;
270 }
271 /* Find largest and smallest lengths in this group */
272 minLen = maxLen = length[0];
273
274 for (i = 1; i < symCount; i++) {
275 if (length[i] > maxLen)
276 maxLen = length[i];
277 else if (length[i] < minLen)
278 minLen = length[i];
279 }
280
281 /* Calculate permute[], base[], and limit[] tables from
282 * length[].
283 *
284 * permute[] is the lookup table for converting
285 * Huffman coded symbols into decoded symbols. base[]
286 * is the amount to subtract from the value of a
287 * Huffman symbol of a given length when using
288 * permute[].
289 *
290 * limit[] indicates the largest numerical value a
291 * symbol with a given number of bits can have. This
292 * is how the Huffman codes can vary in length: each
293 * code with a value > limit[length] needs another
294 * bit.
295 */
296 hufGroup = bd->groups+j;
297 hufGroup->minLen = minLen;
298 hufGroup->maxLen = maxLen;
299 /* Note that minLen can't be smaller than 1, so we
300 adjust the base and limit array pointers so we're
301 not always wasting the first entry. We do this
302 again when using them (during symbol decoding).*/
303 base = hufGroup->base-1;
304 limit = hufGroup->limit-1;
305 /* Calculate permute[]. Concurrently, initialize
306 * temp[] and limit[]. */
307 pp = 0;
308 for (i = minLen; i <= maxLen; i++) {
309 temp[i] = limit[i] = 0;
310 for (t = 0; t < symCount; t++)
311 if (length[t] == i)
312 hufGroup->permute[pp++] = t;
313 }
314 /* Count symbols coded for at each bit length */
315 for (i = 0; i < symCount; i++)
316 temp[length[i]]++;
317 /* Calculate limit[] (the largest symbol-coding value
318 *at each bit length, which is (previous limit <<
319 *1)+symbols at this level), and base[] (number of
320 *symbols to ignore at each bit length, which is limit
321 *minus the cumulative count of symbols coded for
322 *already). */
323 pp = t = 0;
324 for (i = minLen; i < maxLen; i++) {
325 pp += temp[i];
326 /* We read the largest possible symbol size
327 and then unget bits after determining how
328 many we need, and those extra bits could be
329 set to anything. (They're noise from
330 future symbols.) At each level we're
331 really only interested in the first few
332 bits, so here we set all the trailing
333 to-be-ignored bits to 1 so they don't
334 affect the value > limit[length]
335 comparison. */
336 limit[i] = (pp << (maxLen - i)) - 1;
337 pp <<= 1;
338 base[i+1] = pp-(t += temp[i]);
339 }
340 limit[maxLen+1] = INT_MAX; /* Sentinal value for
341 * reading next sym. */
342 limit[maxLen] = pp+temp[maxLen]-1;
343 base[minLen] = 0;
344 }
345 /* We've finished reading and digesting the block header. Now
346 read this block's Huffman coded symbols from the file and
347 undo the Huffman coding and run length encoding, saving the
348 result into dbuf[dbufCount++] = uc */
349
350 /* Initialize symbol occurrence counters and symbol Move To
351 * Front table */
352 for (i = 0; i < 256; i++) {
353 byteCount[i] = 0;
354 mtfSymbol[i] = (unsigned char)i;
355 }
356 /* Loop through compressed symbols. */
357 runPos = dbufCount = symCount = selector = 0;
358 for (;;) {
359 /* Determine which Huffman coding group to use. */
360 if (!(symCount--)) {
361 symCount = GROUP_SIZE-1;
362 if (selector >= nSelectors)
363 return RETVAL_DATA_ERROR;
364 hufGroup = bd->groups+selectors[selector++];
365 base = hufGroup->base-1;
366 limit = hufGroup->limit-1;
367 }
368 /* Read next Huffman-coded symbol. */
369 /* Note: It is far cheaper to read maxLen bits and
370 back up than it is to read minLen bits and then an
371 additional bit at a time, testing as we go.
372 Because there is a trailing last block (with file
373 CRC), there is no danger of the overread causing an
374 unexpected EOF for a valid compressed file. As a
375 further optimization, we do the read inline
376 (falling back to a call to get_bits if the buffer
377 runs dry). The following (up to got_huff_bits:) is
378 equivalent to j = get_bits(bd, hufGroup->maxLen);
379 */
380 while (bd->inbufBitCount < hufGroup->maxLen) {
381 if (bd->inbufPos == bd->inbufCount) {
382 j = get_bits(bd, hufGroup->maxLen);
383 goto got_huff_bits;
384 }
385 bd->inbufBits =
386 (bd->inbufBits << 8)|bd->inbuf[bd->inbufPos++];
387 bd->inbufBitCount += 8;
388 };
389 bd->inbufBitCount -= hufGroup->maxLen;
390 j = (bd->inbufBits >> bd->inbufBitCount)&
391 ((1 << hufGroup->maxLen)-1);
392got_huff_bits:
393 /* Figure how how many bits are in next symbol and
394 * unget extras */
395 i = hufGroup->minLen;
396 while (j > limit[i])
397 ++i;
398 bd->inbufBitCount += (hufGroup->maxLen - i);
399 /* Huffman decode value to get nextSym (with bounds checking) */
400 if ((i > hufGroup->maxLen)
401 || (((unsigned)(j = (j>>(hufGroup->maxLen-i))-base[i]))
402 >= MAX_SYMBOLS))
403 return RETVAL_DATA_ERROR;
404 nextSym = hufGroup->permute[j];
405 /* We have now decoded the symbol, which indicates
406 either a new literal byte, or a repeated run of the
407 most recent literal byte. First, check if nextSym
408 indicates a repeated run, and if so loop collecting
409 how many times to repeat the last literal. */
410 if (((unsigned)nextSym) <= SYMBOL_RUNB) { /* RUNA or RUNB */
411 /* If this is the start of a new run, zero out
412 * counter */
413 if (!runPos) {
414 runPos = 1;
415 t = 0;
416 }
417 /* Neat trick that saves 1 symbol: instead of
418 or-ing 0 or 1 at each bit position, add 1
419 or 2 instead. For example, 1011 is 1 << 0
420 + 1 << 1 + 2 << 2. 1010 is 2 << 0 + 2 << 1
421 + 1 << 2. You can make any bit pattern
422 that way using 1 less symbol than the basic
423 or 0/1 method (except all bits 0, which
424 would use no symbols, but a run of length 0
425 doesn't mean anything in this context).
426 Thus space is saved. */
427 t += (runPos << nextSym);
428 /* +runPos if RUNA; +2*runPos if RUNB */
429
430 runPos <<= 1;
431 continue;
432 }
433 /* When we hit the first non-run symbol after a run,
434 we now know how many times to repeat the last
435 literal, so append that many copies to our buffer
436 of decoded symbols (dbuf) now. (The last literal
437 used is the one at the head of the mtfSymbol
438 array.) */
439 if (runPos) {
440 runPos = 0;
441 if (dbufCount+t >= dbufSize)
442 return RETVAL_DATA_ERROR;
443
444 uc = symToByte[mtfSymbol[0]];
445 byteCount[uc] += t;
446 while (t--)
447 dbuf[dbufCount++] = uc;
448 }
449 /* Is this the terminating symbol? */
450 if (nextSym > symTotal)
451 break;
452 /* At this point, nextSym indicates a new literal
453 character. Subtract one to get the position in the
454 MTF array at which this literal is currently to be
455 found. (Note that the result can't be -1 or 0,
456 because 0 and 1 are RUNA and RUNB. But another
457 instance of the first symbol in the mtf array,
458 position 0, would have been handled as part of a
459 run above. Therefore 1 unused mtf position minus 2
460 non-literal nextSym values equals -1.) */
461 if (dbufCount >= dbufSize)
462 return RETVAL_DATA_ERROR;
463 i = nextSym - 1;
464 uc = mtfSymbol[i];
465 /* Adjust the MTF array. Since we typically expect to
466 *move only a small number of symbols, and are bound
467 *by 256 in any case, using memmove here would
468 *typically be bigger and slower due to function call
469 *overhead and other assorted setup costs. */
470 do {
471 mtfSymbol[i] = mtfSymbol[i-1];
472 } while (--i);
473 mtfSymbol[0] = uc;
474 uc = symToByte[uc];
475 /* We have our literal byte. Save it into dbuf. */
476 byteCount[uc]++;
477 dbuf[dbufCount++] = (unsigned int)uc;
478 }
479 /* At this point, we've read all the Huffman-coded symbols
480 (and repeated runs) for this block from the input stream,
481 and decoded them into the intermediate buffer. There are
482 dbufCount many decoded bytes in dbuf[]. Now undo the
483 Burrows-Wheeler transform on dbuf. See
484 http://dogma.net/markn/articles/bwt/bwt.htm
485 */
486 /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */
487 j = 0;
488 for (i = 0; i < 256; i++) {
489 k = j+byteCount[i];
490 byteCount[i] = j;
491 j = k;
492 }
493 /* Figure out what order dbuf would be in if we sorted it. */
494 for (i = 0; i < dbufCount; i++) {
495 uc = (unsigned char)(dbuf[i] & 0xff);
496 dbuf[byteCount[uc]] |= (i << 8);
497 byteCount[uc]++;
498 }
499 /* Decode first byte by hand to initialize "previous" byte.
500 Note that it doesn't get output, and if the first three
501 characters are identical it doesn't qualify as a run (hence
502 writeRunCountdown = 5). */
503 if (dbufCount) {
504 if (origPtr >= dbufCount)
505 return RETVAL_DATA_ERROR;
506 bd->writePos = dbuf[origPtr];
507 bd->writeCurrent = (unsigned char)(bd->writePos&0xff);
508 bd->writePos >>= 8;
509 bd->writeRunCountdown = 5;
510 }
511 bd->writeCount = dbufCount;
512
513 return RETVAL_OK;
514}
515
516/* Undo burrows-wheeler transform on intermediate buffer to produce output.
517 If start_bunzip was initialized with out_fd =-1, then up to len bytes of
518 data are written to outbuf. Return value is number of bytes written or
519 error (all errors are negative numbers). If out_fd!=-1, outbuf and len
520 are ignored, data is written to out_fd and return is RETVAL_OK or error.
521*/
522
523static int INIT read_bunzip(struct bunzip_data *bd, char *outbuf, int len)
524{
525 const unsigned int *dbuf;
526 int pos, xcurrent, previous, gotcount;
527
528 /* If last read was short due to end of file, return last block now */
529 if (bd->writeCount < 0)
530 return bd->writeCount;
531
532 gotcount = 0;
533 dbuf = bd->dbuf;
534 pos = bd->writePos;
535 xcurrent = bd->writeCurrent;
536
537 /* We will always have pending decoded data to write into the output
538 buffer unless this is the very first call (in which case we haven't
539 Huffman-decoded a block into the intermediate buffer yet). */
540
541 if (bd->writeCopies) {
542 /* Inside the loop, writeCopies means extra copies (beyond 1) */
543 --bd->writeCopies;
544 /* Loop outputting bytes */
545 for (;;) {
546 /* If the output buffer is full, snapshot
547 * state and return */
548 if (gotcount >= len) {
549 bd->writePos = pos;
550 bd->writeCurrent = xcurrent;
551 bd->writeCopies++;
552 return len;
553 }
554 /* Write next byte into output buffer, updating CRC */
555 outbuf[gotcount++] = xcurrent;
556 bd->writeCRC = (((bd->writeCRC) << 8)
557 ^bd->crc32Table[((bd->writeCRC) >> 24)
558 ^xcurrent]);
559 /* Loop now if we're outputting multiple
560 * copies of this byte */
561 if (bd->writeCopies) {
562 --bd->writeCopies;
563 continue;
564 }
565decode_next_byte:
566 if (!bd->writeCount--)
567 break;
568 /* Follow sequence vector to undo
569 * Burrows-Wheeler transform */
570 previous = xcurrent;
571 pos = dbuf[pos];
572 xcurrent = pos&0xff;
573 pos >>= 8;
574 /* After 3 consecutive copies of the same
575 byte, the 4th is a repeat count. We count
576 down from 4 instead *of counting up because
577 testing for non-zero is faster */
578 if (--bd->writeRunCountdown) {
579 if (xcurrent != previous)
580 bd->writeRunCountdown = 4;
581 } else {
582 /* We have a repeated run, this byte
583 * indicates the count */
584 bd->writeCopies = xcurrent;
585 xcurrent = previous;
586 bd->writeRunCountdown = 5;
587 /* Sometimes there are just 3 bytes
588 * (run length 0) */
589 if (!bd->writeCopies)
590 goto decode_next_byte;
591 /* Subtract the 1 copy we'd output
592 * anyway to get extras */
593 --bd->writeCopies;
594 }
595 }
596 /* Decompression of this block completed successfully */
597 bd->writeCRC = ~bd->writeCRC;
598 bd->totalCRC = ((bd->totalCRC << 1) |
599 (bd->totalCRC >> 31)) ^ bd->writeCRC;
600 /* If this block had a CRC error, force file level CRC error. */
601 if (bd->writeCRC != bd->headerCRC) {
602 bd->totalCRC = bd->headerCRC+1;
603 return RETVAL_LAST_BLOCK;
604 }
605 }
606
607 /* Refill the intermediate buffer by Huffman-decoding next
608 * block of input */
609 /* (previous is just a convenient unused temp variable here) */
610 previous = get_next_block(bd);
611 if (previous) {
612 bd->writeCount = previous;
613 return (previous != RETVAL_LAST_BLOCK) ? previous : gotcount;
614 }
615 bd->writeCRC = 0xffffffffUL;
616 pos = bd->writePos;
617 xcurrent = bd->writeCurrent;
618 goto decode_next_byte;
619}
620
621static long INIT nofill(void *buf, unsigned long len)
622{
623 return -1;
624}
625
626/* Allocate the structure, read file header. If in_fd ==-1, inbuf must contain
627 a complete bunzip file (len bytes long). If in_fd!=-1, inbuf and len are
628 ignored, and data is read from file handle into temporary buffer. */
629static int INIT start_bunzip(struct bunzip_data **bdp, void *inbuf, long len,
630 long (*fill)(void*, unsigned long))
631{
632 struct bunzip_data *bd;
633 unsigned int i, j, c;
634 const unsigned int BZh0 =
635 (((unsigned int)'B') << 24)+(((unsigned int)'Z') << 16)
636 +(((unsigned int)'h') << 8)+(unsigned int)'0';
637
638 /* Figure out how much data to allocate */
639 i = sizeof(struct bunzip_data);
640
641 /* Allocate bunzip_data. Most fields initialize to zero. */
642 bd = *bdp = malloc(i);
643 if (!bd)
644 return RETVAL_OUT_OF_MEMORY;
645 memset(bd, 0, sizeof(struct bunzip_data));
646 /* Setup input buffer */
647 bd->inbuf = inbuf;
648 bd->inbufCount = len;
649 if (fill != NULL)
650 bd->fill = fill;
651 else
652 bd->fill = nofill;
653
654 /* Init the CRC32 table (big endian) */
655 for (i = 0; i < 256; i++) {
656 c = i << 24;
657 for (j = 8; j; j--)
658 c = c&0x80000000 ? (c << 1)^(CRC32_POLY_BE) : (c << 1);
659 bd->crc32Table[i] = c;
660 }
661
662 /* Ensure that file starts with "BZh['1'-'9']." */
663 i = get_bits(bd, 32);
664 if (((unsigned int)(i-BZh0-1)) >= 9)
665 return RETVAL_NOT_BZIP_DATA;
666
667 /* Fourth byte (ascii '1'-'9'), indicates block size in units of 100k of
668 uncompressed data. Allocate intermediate buffer for block. */
669 bd->dbufSize = 100000*(i-BZh0);
670
671 bd->dbuf = large_malloc(bd->dbufSize * sizeof(int));
672 if (!bd->dbuf)
673 return RETVAL_OUT_OF_MEMORY;
674 return RETVAL_OK;
675}
676
677/* Example usage: decompress src_fd to dst_fd. (Stops at end of bzip2 data,
678 not end of file.) */
679STATIC int INIT bunzip2(unsigned char *buf, long len,
680 long (*fill)(void*, unsigned long),
681 long (*flush)(void*, unsigned long),
682 unsigned char *outbuf,
683 long *pos,
684 void(*error)(char *x))
685{
686 struct bunzip_data *bd;
687 int i = -1;
688 unsigned char *inbuf;
689
690 if (flush)
691 outbuf = malloc(BZIP2_IOBUF_SIZE);
692
693 if (!outbuf) {
694 error("Could not allocate output buffer");
695 return RETVAL_OUT_OF_MEMORY;
696 }
697 if (buf)
698 inbuf = buf;
699 else
700 inbuf = malloc(BZIP2_IOBUF_SIZE);
701 if (!inbuf) {
702 error("Could not allocate input buffer");
703 i = RETVAL_OUT_OF_MEMORY;
704 goto exit_0;
705 }
706 i = start_bunzip(&bd, inbuf, len, fill);
707 if (!i) {
708 for (;;) {
709 i = read_bunzip(bd, outbuf, BZIP2_IOBUF_SIZE);
710 if (i <= 0)
711 break;
712 if (!flush)
713 outbuf += i;
714 else
715 if (i != flush(outbuf, i)) {
716 i = RETVAL_UNEXPECTED_OUTPUT_EOF;
717 break;
718 }
719 }
720 }
721 /* Check CRC and release memory */
722 if (i == RETVAL_LAST_BLOCK) {
723 if (bd->headerCRC != bd->totalCRC)
724 error("Data integrity error when decompressing.");
725 else
726 i = RETVAL_OK;
727 } else if (i == RETVAL_UNEXPECTED_OUTPUT_EOF) {
728 error("Compressed file ends unexpectedly");
729 }
730 if (!bd)
731 goto exit_1;
732 if (bd->dbuf)
733 large_free(bd->dbuf);
734 if (pos)
735 *pos = bd->inbufPos;
736 free(bd);
737exit_1:
738 if (!buf)
739 free(inbuf);
740exit_0:
741 if (flush)
742 free(outbuf);
743 return i;
744}
745
746#ifdef PREBOOT
747STATIC int INIT __decompress(unsigned char *buf, long len,
748 long (*fill)(void*, unsigned long),
749 long (*flush)(void*, unsigned long),
750 unsigned char *outbuf, long olen,
751 long *pos,
752 void (*error)(char *x))
753{
754 return bunzip2(buf, len - 4, fill, flush, outbuf, pos, error);
755}
756#endif
757