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1/* vi: set sw = 4 ts = 4: */
2/* Small bzip2 deflate implementation, by Rob Landley (rob@landley.net).
3
4 Based on bzip2 decompression code by Julian R Seward (jseward@acm.org),
5 which also acknowledges contributions by Mike Burrows, David Wheeler,
6 Peter Fenwick, Alistair Moffat, Radford Neal, Ian H. Witten,
7 Robert Sedgewick, and Jon L. Bentley.
8
9 This code is licensed under the LGPLv2:
10 LGPL (http://www.gnu.org/copyleft/lgpl.html
11*/
12
13/*
14 Size and speed optimizations by Manuel Novoa III (mjn3@codepoet.org).
15
16 More efficient reading of Huffman codes, a streamlined read_bunzip()
17 function, and various other tweaks. In (limited) tests, approximately
18 20% faster than bzcat on x86 and about 10% faster on arm.
19
20 Note that about 2/3 of the time is spent in read_unzip() reversing
21 the Burrows-Wheeler transformation. Much of that time is delay
22 resulting from cache misses.
23
24 I would ask that anyone benefiting from this work, especially those
25 using it in commercial products, consider making a donation to my local
26 non-profit hospice organization in the name of the woman I loved, who
27 passed away Feb. 12, 2003.
28
29 In memory of Toni W. Hagan
30
31 Hospice of Acadiana, Inc.
32 2600 Johnston St., Suite 200
33 Lafayette, LA 70503-3240
34
35 Phone (337) 232-1234 or 1-800-738-2226
36 Fax (337) 232-1297
37
38 http://www.hospiceacadiana.com/
39
40 Manuel
41 */
42
43/*
44 Made it fit for running in Linux Kernel by Alain Knaff (alain@knaff.lu)
45*/
46
47
48#ifndef STATIC
49#include <linux/decompress/bunzip2.h>
50#endif /* !STATIC */
51
52#include <linux/decompress/mm.h>
53#include <linux/slab.h>
54
55#ifndef INT_MAX
56#define INT_MAX 0x7fffffff
57#endif
58
59/* Constants for Huffman coding */
60#define MAX_GROUPS 6
61#define GROUP_SIZE 50 /* 64 would have been more efficient */
62#define MAX_HUFCODE_BITS 20 /* Longest Huffman code allowed */
63#define MAX_SYMBOLS 258 /* 256 literals + RUNA + RUNB */
64#define SYMBOL_RUNA 0
65#define SYMBOL_RUNB 1
66
67/* Status return values */
68#define RETVAL_OK 0
69#define RETVAL_LAST_BLOCK (-1)
70#define RETVAL_NOT_BZIP_DATA (-2)
71#define RETVAL_UNEXPECTED_INPUT_EOF (-3)
72#define RETVAL_UNEXPECTED_OUTPUT_EOF (-4)
73#define RETVAL_DATA_ERROR (-5)
74#define RETVAL_OUT_OF_MEMORY (-6)
75#define RETVAL_OBSOLETE_INPUT (-7)
76
77/* Other housekeeping constants */
78#define BZIP2_IOBUF_SIZE 4096
79
80/* This is what we know about each Huffman coding group */
81struct group_data {
82 /* We have an extra slot at the end of limit[] for a sentinal value. */
83 int limit[MAX_HUFCODE_BITS+1];
84 int base[MAX_HUFCODE_BITS];
85 int permute[MAX_SYMBOLS];
86 int minLen, maxLen;
87};
88
89/* Structure holding all the housekeeping data, including IO buffers and
90 memory that persists between calls to bunzip */
91struct bunzip_data {
92 /* State for interrupting output loop */
93 int writeCopies, writePos, writeRunCountdown, writeCount, writeCurrent;
94 /* I/O tracking data (file handles, buffers, positions, etc.) */
95 int (*fill)(void*, unsigned int);
96 int inbufCount, inbufPos /*, outbufPos*/;
97 unsigned char *inbuf /*,*outbuf*/;
98 unsigned int inbufBitCount, inbufBits;
99 /* The CRC values stored in the block header and calculated from the
100 data */
101 unsigned int crc32Table[256], headerCRC, totalCRC, writeCRC;
102 /* Intermediate buffer and its size (in bytes) */
103 unsigned int *dbuf, dbufSize;
104 /* These things are a bit too big to go on the stack */
105 unsigned char selectors[32768]; /* nSelectors = 15 bits */
106 struct group_data groups[MAX_GROUPS]; /* Huffman coding tables */
107 int io_error; /* non-zero if we have IO error */
108};
109
110
111/* Return the next nnn bits of input. All reads from the compressed input
112 are done through this function. All reads are big endian */
113static unsigned int INIT get_bits(struct bunzip_data *bd, char bits_wanted)
114{
115 unsigned int bits = 0;
116
117 /* If we need to get more data from the byte buffer, do so.
118 (Loop getting one byte at a time to enforce endianness and avoid
119 unaligned access.) */
120 while (bd->inbufBitCount < bits_wanted) {
121 /* If we need to read more data from file into byte buffer, do
122 so */
123 if (bd->inbufPos == bd->inbufCount) {
124 if (bd->io_error)
125 return 0;
126 bd->inbufCount = bd->fill(bd->inbuf, BZIP2_IOBUF_SIZE);
127 if (bd->inbufCount <= 0) {
128 bd->io_error = RETVAL_UNEXPECTED_INPUT_EOF;
129 return 0;
130 }
131 bd->inbufPos = 0;
132 }
133 /* Avoid 32-bit overflow (dump bit buffer to top of output) */
134 if (bd->inbufBitCount >= 24) {
135 bits = bd->inbufBits&((1 << bd->inbufBitCount)-1);
136 bits_wanted -= bd->inbufBitCount;
137 bits <<= bits_wanted;
138 bd->inbufBitCount = 0;
139 }
140 /* Grab next 8 bits of input from buffer. */
141 bd->inbufBits = (bd->inbufBits << 8)|bd->inbuf[bd->inbufPos++];
142 bd->inbufBitCount += 8;
143 }
144 /* Calculate result */
145 bd->inbufBitCount -= bits_wanted;
146 bits |= (bd->inbufBits >> bd->inbufBitCount)&((1 << bits_wanted)-1);
147
148 return bits;
149}
150
151/* Unpacks the next block and sets up for the inverse burrows-wheeler step. */
152
153static int INIT get_next_block(struct bunzip_data *bd)
154{
155 struct group_data *hufGroup = NULL;
156 int *base = NULL;
157 int *limit = NULL;
158 int dbufCount, nextSym, dbufSize, groupCount, selector,
159 i, j, k, t, runPos, symCount, symTotal, nSelectors,
160 byteCount[256];
161 unsigned char uc, symToByte[256], mtfSymbol[256], *selectors;
162 unsigned int *dbuf, origPtr;
163
164 dbuf = bd->dbuf;
165 dbufSize = bd->dbufSize;
166 selectors = bd->selectors;
167
168 /* Read in header signature and CRC, then validate signature.
169 (last block signature means CRC is for whole file, return now) */
170 i = get_bits(bd, 24);
171 j = get_bits(bd, 24);
172 bd->headerCRC = get_bits(bd, 32);
173 if ((i == 0x177245) && (j == 0x385090))
174 return RETVAL_LAST_BLOCK;
175 if ((i != 0x314159) || (j != 0x265359))
176 return RETVAL_NOT_BZIP_DATA;
177 /* We can add support for blockRandomised if anybody complains.
178 There was some code for this in busybox 1.0.0-pre3, but nobody ever
179 noticed that it didn't actually work. */
180 if (get_bits(bd, 1))
181 return RETVAL_OBSOLETE_INPUT;
182 origPtr = get_bits(bd, 24);
183 if (origPtr > dbufSize)
184 return RETVAL_DATA_ERROR;
185 /* mapping table: if some byte values are never used (encoding things
186 like ascii text), the compression code removes the gaps to have fewer
187 symbols to deal with, and writes a sparse bitfield indicating which
188 values were present. We make a translation table to convert the
189 symbols back to the corresponding bytes. */
190 t = get_bits(bd, 16);
191 symTotal = 0;
192 for (i = 0; i < 16; i++) {
193 if (t&(1 << (15-i))) {
194 k = get_bits(bd, 16);
195 for (j = 0; j < 16; j++)
196 if (k&(1 << (15-j)))
197 symToByte[symTotal++] = (16*i)+j;
198 }
199 }
200 /* How many different Huffman coding groups does this block use? */
201 groupCount = get_bits(bd, 3);
202 if (groupCount < 2 || groupCount > MAX_GROUPS)
203 return RETVAL_DATA_ERROR;
204 /* nSelectors: Every GROUP_SIZE many symbols we select a new
205 Huffman coding group. Read in the group selector list,
206 which is stored as MTF encoded bit runs. (MTF = Move To
207 Front, as each value is used it's moved to the start of the
208 list.) */
209 nSelectors = get_bits(bd, 15);
210 if (!nSelectors)
211 return RETVAL_DATA_ERROR;
212 for (i = 0; i < groupCount; i++)
213 mtfSymbol[i] = i;
214 for (i = 0; i < nSelectors; i++) {
215 /* Get next value */
216 for (j = 0; get_bits(bd, 1); j++)
217 if (j >= groupCount)
218 return RETVAL_DATA_ERROR;
219 /* Decode MTF to get the next selector */
220 uc = mtfSymbol[j];
221 for (; j; j--)
222 mtfSymbol[j] = mtfSymbol[j-1];
223 mtfSymbol[0] = selectors[i] = uc;
224 }
225 /* Read the Huffman coding tables for each group, which code
226 for symTotal literal symbols, plus two run symbols (RUNA,
227 RUNB) */
228 symCount = symTotal+2;
229 for (j = 0; j < groupCount; j++) {
230 unsigned char length[MAX_SYMBOLS], temp[MAX_HUFCODE_BITS+1];
231 int minLen, maxLen, pp;
232 /* Read Huffman code lengths for each symbol. They're
233 stored in a way similar to mtf; record a starting
234 value for the first symbol, and an offset from the
235 previous value for everys symbol after that.
236 (Subtracting 1 before the loop and then adding it
237 back at the end is an optimization that makes the
238 test inside the loop simpler: symbol length 0
239 becomes negative, so an unsigned inequality catches
240 it.) */
241 t = get_bits(bd, 5)-1;
242 for (i = 0; i < symCount; i++) {
243 for (;;) {
244 if (((unsigned)t) > (MAX_HUFCODE_BITS-1))
245 return RETVAL_DATA_ERROR;
246
247 /* If first bit is 0, stop. Else
248 second bit indicates whether to
249 increment or decrement the value.
250 Optimization: grab 2 bits and unget
251 the second if the first was 0. */
252
253 k = get_bits(bd, 2);
254 if (k < 2) {
255 bd->inbufBitCount++;
256 break;
257 }
258 /* Add one if second bit 1, else
259 * subtract 1. Avoids if/else */
260 t += (((k+1)&2)-1);
261 }
262 /* Correct for the initial -1, to get the
263 * final symbol length */
264 length[i] = t+1;
265 }
266 /* Find largest and smallest lengths in this group */
267 minLen = maxLen = length[0];
268
269 for (i = 1; i < symCount; i++) {
270 if (length[i] > maxLen)
271 maxLen = length[i];
272 else if (length[i] < minLen)
273 minLen = length[i];
274 }
275
276 /* Calculate permute[], base[], and limit[] tables from
277 * length[].
278 *
279 * permute[] is the lookup table for converting
280 * Huffman coded symbols into decoded symbols. base[]
281 * is the amount to subtract from the value of a
282 * Huffman symbol of a given length when using
283 * permute[].
284 *
285 * limit[] indicates the largest numerical value a
286 * symbol with a given number of bits can have. This
287 * is how the Huffman codes can vary in length: each
288 * code with a value > limit[length] needs another
289 * bit.
290 */
291 hufGroup = bd->groups+j;
292 hufGroup->minLen = minLen;
293 hufGroup->maxLen = maxLen;
294 /* Note that minLen can't be smaller than 1, so we
295 adjust the base and limit array pointers so we're
296 not always wasting the first entry. We do this
297 again when using them (during symbol decoding).*/
298 base = hufGroup->base-1;
299 limit = hufGroup->limit-1;
300 /* Calculate permute[]. Concurently, initialize
301 * temp[] and limit[]. */
302 pp = 0;
303 for (i = minLen; i <= maxLen; i++) {
304 temp[i] = limit[i] = 0;
305 for (t = 0; t < symCount; t++)
306 if (length[t] == i)
307 hufGroup->permute[pp++] = t;
308 }
309 /* Count symbols coded for at each bit length */
310 for (i = 0; i < symCount; i++)
311 temp[length[i]]++;
312 /* Calculate limit[] (the largest symbol-coding value
313 *at each bit length, which is (previous limit <<
314 *1)+symbols at this level), and base[] (number of
315 *symbols to ignore at each bit length, which is limit
316 *minus the cumulative count of symbols coded for
317 *already). */
318 pp = t = 0;
319 for (i = minLen; i < maxLen; i++) {
320 pp += temp[i];
321 /* We read the largest possible symbol size
322 and then unget bits after determining how
323 many we need, and those extra bits could be
324 set to anything. (They're noise from
325 future symbols.) At each level we're
326 really only interested in the first few
327 bits, so here we set all the trailing
328 to-be-ignored bits to 1 so they don't
329 affect the value > limit[length]
330 comparison. */
331 limit[i] = (pp << (maxLen - i)) - 1;
332 pp <<= 1;
333 base[i+1] = pp-(t += temp[i]);
334 }
335 limit[maxLen+1] = INT_MAX; /* Sentinal value for
336 * reading next sym. */
337 limit[maxLen] = pp+temp[maxLen]-1;
338 base[minLen] = 0;
339 }
340 /* We've finished reading and digesting the block header. Now
341 read this block's Huffman coded symbols from the file and
342 undo the Huffman coding and run length encoding, saving the
343 result into dbuf[dbufCount++] = uc */
344
345 /* Initialize symbol occurrence counters and symbol Move To
346 * Front table */
347 for (i = 0; i < 256; i++) {
348 byteCount[i] = 0;
349 mtfSymbol[i] = (unsigned char)i;
350 }
351 /* Loop through compressed symbols. */
352 runPos = dbufCount = symCount = selector = 0;
353 for (;;) {
354 /* Determine which Huffman coding group to use. */
355 if (!(symCount--)) {
356 symCount = GROUP_SIZE-1;
357 if (selector >= nSelectors)
358 return RETVAL_DATA_ERROR;
359 hufGroup = bd->groups+selectors[selector++];
360 base = hufGroup->base-1;
361 limit = hufGroup->limit-1;
362 }
363 /* Read next Huffman-coded symbol. */
364 /* Note: It is far cheaper to read maxLen bits and
365 back up than it is to read minLen bits and then an
366 additional bit at a time, testing as we go.
367 Because there is a trailing last block (with file
368 CRC), there is no danger of the overread causing an
369 unexpected EOF for a valid compressed file. As a
370 further optimization, we do the read inline
371 (falling back to a call to get_bits if the buffer
372 runs dry). The following (up to got_huff_bits:) is
373 equivalent to j = get_bits(bd, hufGroup->maxLen);
374 */
375 while (bd->inbufBitCount < hufGroup->maxLen) {
376 if (bd->inbufPos == bd->inbufCount) {
377 j = get_bits(bd, hufGroup->maxLen);
378 goto got_huff_bits;
379 }
380 bd->inbufBits =
381 (bd->inbufBits << 8)|bd->inbuf[bd->inbufPos++];
382 bd->inbufBitCount += 8;
383 };
384 bd->inbufBitCount -= hufGroup->maxLen;
385 j = (bd->inbufBits >> bd->inbufBitCount)&
386 ((1 << hufGroup->maxLen)-1);
387got_huff_bits:
388 /* Figure how how many bits are in next symbol and
389 * unget extras */
390 i = hufGroup->minLen;
391 while (j > limit[i])
392 ++i;
393 bd->inbufBitCount += (hufGroup->maxLen - i);
394 /* Huffman decode value to get nextSym (with bounds checking) */
395 if ((i > hufGroup->maxLen)
396 || (((unsigned)(j = (j>>(hufGroup->maxLen-i))-base[i]))
397 >= MAX_SYMBOLS))
398 return RETVAL_DATA_ERROR;
399 nextSym = hufGroup->permute[j];
400 /* We have now decoded the symbol, which indicates
401 either a new literal byte, or a repeated run of the
402 most recent literal byte. First, check if nextSym
403 indicates a repeated run, and if so loop collecting
404 how many times to repeat the last literal. */
405 if (((unsigned)nextSym) <= SYMBOL_RUNB) { /* RUNA or RUNB */
406 /* If this is the start of a new run, zero out
407 * counter */
408 if (!runPos) {
409 runPos = 1;
410 t = 0;
411 }
412 /* Neat trick that saves 1 symbol: instead of
413 or-ing 0 or 1 at each bit position, add 1
414 or 2 instead. For example, 1011 is 1 << 0
415 + 1 << 1 + 2 << 2. 1010 is 2 << 0 + 2 << 1
416 + 1 << 2. You can make any bit pattern
417 that way using 1 less symbol than the basic
418 or 0/1 method (except all bits 0, which
419 would use no symbols, but a run of length 0
420 doesn't mean anything in this context).
421 Thus space is saved. */
422 t += (runPos << nextSym);
423 /* +runPos if RUNA; +2*runPos if RUNB */
424
425 runPos <<= 1;
426 continue;
427 }
428 /* When we hit the first non-run symbol after a run,
429 we now know how many times to repeat the last
430 literal, so append that many copies to our buffer
431 of decoded symbols (dbuf) now. (The last literal
432 used is the one at the head of the mtfSymbol
433 array.) */
434 if (runPos) {
435 runPos = 0;
436 if (dbufCount+t >= dbufSize)
437 return RETVAL_DATA_ERROR;
438
439 uc = symToByte[mtfSymbol[0]];
440 byteCount[uc] += t;
441 while (t--)
442 dbuf[dbufCount++] = uc;
443 }
444 /* Is this the terminating symbol? */
445 if (nextSym > symTotal)
446 break;
447 /* At this point, nextSym indicates a new literal
448 character. Subtract one to get the position in the
449 MTF array at which this literal is currently to be
450 found. (Note that the result can't be -1 or 0,
451 because 0 and 1 are RUNA and RUNB. But another
452 instance of the first symbol in the mtf array,
453 position 0, would have been handled as part of a
454 run above. Therefore 1 unused mtf position minus 2
455 non-literal nextSym values equals -1.) */
456 if (dbufCount >= dbufSize)
457 return RETVAL_DATA_ERROR;
458 i = nextSym - 1;
459 uc = mtfSymbol[i];
460 /* Adjust the MTF array. Since we typically expect to
461 *move only a small number of symbols, and are bound
462 *by 256 in any case, using memmove here would
463 *typically be bigger and slower due to function call
464 *overhead and other assorted setup costs. */
465 do {
466 mtfSymbol[i] = mtfSymbol[i-1];
467 } while (--i);
468 mtfSymbol[0] = uc;
469 uc = symToByte[uc];
470 /* We have our literal byte. Save it into dbuf. */
471 byteCount[uc]++;
472 dbuf[dbufCount++] = (unsigned int)uc;
473 }
474 /* At this point, we've read all the Huffman-coded symbols
475 (and repeated runs) for this block from the input stream,
476 and decoded them into the intermediate buffer. There are
477 dbufCount many decoded bytes in dbuf[]. Now undo the
478 Burrows-Wheeler transform on dbuf. See
479 http://dogma.net/markn/articles/bwt/bwt.htm
480 */
481 /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */
482 j = 0;
483 for (i = 0; i < 256; i++) {
484 k = j+byteCount[i];
485 byteCount[i] = j;
486 j = k;
487 }
488 /* Figure out what order dbuf would be in if we sorted it. */
489 for (i = 0; i < dbufCount; i++) {
490 uc = (unsigned char)(dbuf[i] & 0xff);
491 dbuf[byteCount[uc]] |= (i << 8);
492 byteCount[uc]++;
493 }
494 /* Decode first byte by hand to initialize "previous" byte.
495 Note that it doesn't get output, and if the first three
496 characters are identical it doesn't qualify as a run (hence
497 writeRunCountdown = 5). */
498 if (dbufCount) {
499 if (origPtr >= dbufCount)
500 return RETVAL_DATA_ERROR;
501 bd->writePos = dbuf[origPtr];
502 bd->writeCurrent = (unsigned char)(bd->writePos&0xff);
503 bd->writePos >>= 8;
504 bd->writeRunCountdown = 5;
505 }
506 bd->writeCount = dbufCount;
507
508 return RETVAL_OK;
509}
510
511/* Undo burrows-wheeler transform on intermediate buffer to produce output.
512 If start_bunzip was initialized with out_fd =-1, then up to len bytes of
513 data are written to outbuf. Return value is number of bytes written or
514 error (all errors are negative numbers). If out_fd!=-1, outbuf and len
515 are ignored, data is written to out_fd and return is RETVAL_OK or error.
516*/
517
518static int INIT read_bunzip(struct bunzip_data *bd, char *outbuf, int len)
519{
520 const unsigned int *dbuf;
521 int pos, xcurrent, previous, gotcount;
522
523 /* If last read was short due to end of file, return last block now */
524 if (bd->writeCount < 0)
525 return bd->writeCount;
526
527 gotcount = 0;
528 dbuf = bd->dbuf;
529 pos = bd->writePos;
530 xcurrent = bd->writeCurrent;
531
532 /* We will always have pending decoded data to write into the output
533 buffer unless this is the very first call (in which case we haven't
534 Huffman-decoded a block into the intermediate buffer yet). */
535
536 if (bd->writeCopies) {
537 /* Inside the loop, writeCopies means extra copies (beyond 1) */
538 --bd->writeCopies;
539 /* Loop outputting bytes */
540 for (;;) {
541 /* If the output buffer is full, snapshot
542 * state and return */
543 if (gotcount >= len) {
544 bd->writePos = pos;
545 bd->writeCurrent = xcurrent;
546 bd->writeCopies++;
547 return len;
548 }
549 /* Write next byte into output buffer, updating CRC */
550 outbuf[gotcount++] = xcurrent;
551 bd->writeCRC = (((bd->writeCRC) << 8)
552 ^bd->crc32Table[((bd->writeCRC) >> 24)
553 ^xcurrent]);
554 /* Loop now if we're outputting multiple
555 * copies of this byte */
556 if (bd->writeCopies) {
557 --bd->writeCopies;
558 continue;
559 }
560decode_next_byte:
561 if (!bd->writeCount--)
562 break;
563 /* Follow sequence vector to undo
564 * Burrows-Wheeler transform */
565 previous = xcurrent;
566 pos = dbuf[pos];
567 xcurrent = pos&0xff;
568 pos >>= 8;
569 /* After 3 consecutive copies of the same
570 byte, the 4th is a repeat count. We count
571 down from 4 instead *of counting up because
572 testing for non-zero is faster */
573 if (--bd->writeRunCountdown) {
574 if (xcurrent != previous)
575 bd->writeRunCountdown = 4;
576 } else {
577 /* We have a repeated run, this byte
578 * indicates the count */
579 bd->writeCopies = xcurrent;
580 xcurrent = previous;
581 bd->writeRunCountdown = 5;
582 /* Sometimes there are just 3 bytes
583 * (run length 0) */
584 if (!bd->writeCopies)
585 goto decode_next_byte;
586 /* Subtract the 1 copy we'd output
587 * anyway to get extras */
588 --bd->writeCopies;
589 }
590 }
591 /* Decompression of this block completed successfully */
592 bd->writeCRC = ~bd->writeCRC;
593 bd->totalCRC = ((bd->totalCRC << 1) |
594 (bd->totalCRC >> 31)) ^ bd->writeCRC;
595 /* If this block had a CRC error, force file level CRC error. */
596 if (bd->writeCRC != bd->headerCRC) {
597 bd->totalCRC = bd->headerCRC+1;
598 return RETVAL_LAST_BLOCK;
599 }
600 }
601
602 /* Refill the intermediate buffer by Huffman-decoding next
603 * block of input */
604 /* (previous is just a convenient unused temp variable here) */
605 previous = get_next_block(bd);
606 if (previous) {
607 bd->writeCount = previous;
608 return (previous != RETVAL_LAST_BLOCK) ? previous : gotcount;
609 }
610 bd->writeCRC = 0xffffffffUL;
611 pos = bd->writePos;
612 xcurrent = bd->writeCurrent;
613 goto decode_next_byte;
614}
615
616static int INIT nofill(void *buf, unsigned int len)
617{
618 return -1;
619}
620
621/* Allocate the structure, read file header. If in_fd ==-1, inbuf must contain
622 a complete bunzip file (len bytes long). If in_fd!=-1, inbuf and len are
623 ignored, and data is read from file handle into temporary buffer. */
624static int INIT start_bunzip(struct bunzip_data **bdp, void *inbuf, int len,
625 int (*fill)(void*, unsigned int))
626{
627 struct bunzip_data *bd;
628 unsigned int i, j, c;
629 const unsigned int BZh0 =
630 (((unsigned int)'B') << 24)+(((unsigned int)'Z') << 16)
631 +(((unsigned int)'h') << 8)+(unsigned int)'0';
632
633 /* Figure out how much data to allocate */
634 i = sizeof(struct bunzip_data);
635
636 /* Allocate bunzip_data. Most fields initialize to zero. */
637 bd = *bdp = malloc(i);
638 memset(bd, 0, sizeof(struct bunzip_data));
639 /* Setup input buffer */
640 bd->inbuf = inbuf;
641 bd->inbufCount = len;
642 if (fill != NULL)
643 bd->fill = fill;
644 else
645 bd->fill = nofill;
646
647 /* Init the CRC32 table (big endian) */
648 for (i = 0; i < 256; i++) {
649 c = i << 24;
650 for (j = 8; j; j--)
651 c = c&0x80000000 ? (c << 1)^0x04c11db7 : (c << 1);
652 bd->crc32Table[i] = c;
653 }
654
655 /* Ensure that file starts with "BZh['1'-'9']." */
656 i = get_bits(bd, 32);
657 if (((unsigned int)(i-BZh0-1)) >= 9)
658 return RETVAL_NOT_BZIP_DATA;
659
660 /* Fourth byte (ascii '1'-'9'), indicates block size in units of 100k of
661 uncompressed data. Allocate intermediate buffer for block. */
662 bd->dbufSize = 100000*(i-BZh0);
663
664 bd->dbuf = large_malloc(bd->dbufSize * sizeof(int));
665 return RETVAL_OK;
666}
667
668/* Example usage: decompress src_fd to dst_fd. (Stops at end of bzip2 data,
669 not end of file.) */
670STATIC int INIT bunzip2(unsigned char *buf, int len,
671 int(*fill)(void*, unsigned int),
672 int(*flush)(void*, unsigned int),
673 unsigned char *outbuf,
674 int *pos,
675 void(*error_fn)(char *x))
676{
677 struct bunzip_data *bd;
678 int i = -1;
679 unsigned char *inbuf;
680
681 set_error_fn(error_fn);
682 if (flush)
683 outbuf = malloc(BZIP2_IOBUF_SIZE);
684 else
685 len -= 4; /* Uncompressed size hack active in pre-boot
686 environment */
687 if (!outbuf) {
688 error("Could not allocate output bufer");
689 return -1;
690 }
691 if (buf)
692 inbuf = buf;
693 else
694 inbuf = malloc(BZIP2_IOBUF_SIZE);
695 if (!inbuf) {
696 error("Could not allocate input bufer");
697 goto exit_0;
698 }
699 i = start_bunzip(&bd, inbuf, len, fill);
700 if (!i) {
701 for (;;) {
702 i = read_bunzip(bd, outbuf, BZIP2_IOBUF_SIZE);
703 if (i <= 0)
704 break;
705 if (!flush)
706 outbuf += i;
707 else
708 if (i != flush(outbuf, i)) {
709 i = RETVAL_UNEXPECTED_OUTPUT_EOF;
710 break;
711 }
712 }
713 }
714 /* Check CRC and release memory */
715 if (i == RETVAL_LAST_BLOCK) {
716 if (bd->headerCRC != bd->totalCRC)
717 error("Data integrity error when decompressing.");
718 else
719 i = RETVAL_OK;
720 } else if (i == RETVAL_UNEXPECTED_OUTPUT_EOF) {
721 error("Compressed file ends unexpectedly");
722 }
723 if (bd->dbuf)
724 large_free(bd->dbuf);
725 if (pos)
726 *pos = bd->inbufPos;
727 free(bd);
728 if (!buf)
729 free(inbuf);
730exit_0:
731 if (flush)
732 free(outbuf);
733 return i;
734}
735
736#define decompress bunzip2
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-13 21:13:49 -0500