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 https://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 */
82 struct group_data {
83 /* We have an extra slot at the end of limit[] for a sentinel 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 */
92 struct 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 */
116 static 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
156 static 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];
236 unsigned short temp[MAX_HUFCODE_BITS+1];
237 int minLen, maxLen, pp;
238 /* Read Huffman code lengths for each symbol. They're
239 stored in a way similar to mtf; record a starting
240 value for the first symbol, and an offset from the
241 previous value for everys symbol after that.
242 (Subtracting 1 before the loop and then adding it
243 back at the end is an optimization that makes the
244 test inside the loop simpler: symbol length 0
245 becomes negative, so an unsigned inequality catches
246 it.) */
247 t = get_bits(bd, 5)-1;
248 for (i = 0; i < symCount; i++) {
249 for (;;) {
250 if (((unsigned)t) > (MAX_HUFCODE_BITS-1))
251 return RETVAL_DATA_ERROR;
252
253 /* If first bit is 0, stop. Else
254 second bit indicates whether to
255 increment or decrement the value.
256 Optimization: grab 2 bits and unget
257 the second if the first was 0. */
258
259 k = get_bits(bd, 2);
260 if (k < 2) {
261 bd->inbufBitCount++;
262 break;
263 }
264 /* Add one if second bit 1, else
265 * subtract 1. Avoids if/else */
266 t += (((k+1)&2)-1);
267 }
268 /* Correct for the initial -1, to get the
269 * final symbol length */
270 length[i] = t+1;
271 }
272 /* Find largest and smallest lengths in this group */
273 minLen = maxLen = length[0];
274
275 for (i = 1; i < symCount; i++) {
276 if (length[i] > maxLen)
277 maxLen = length[i];
278 else if (length[i] < minLen)
279 minLen = length[i];
280 }
281
282 /* Calculate permute[], base[], and limit[] tables from
283 * length[].
284 *
285 * permute[] is the lookup table for converting
286 * Huffman coded symbols into decoded symbols. base[]
287 * is the amount to subtract from the value of a
288 * Huffman symbol of a given length when using
289 * permute[].
290 *
291 * limit[] indicates the largest numerical value a
292 * symbol with a given number of bits can have. This
293 * is how the Huffman codes can vary in length: each
294 * code with a value > limit[length] needs another
295 * bit.
296 */
297 hufGroup = bd->groups+j;
298 hufGroup->minLen = minLen;
299 hufGroup->maxLen = maxLen;
300 /* Note that minLen can't be smaller than 1, so we
301 adjust the base and limit array pointers so we're
302 not always wasting the first entry. We do this
303 again when using them (during symbol decoding).*/
304 base = hufGroup->base-1;
305 limit = hufGroup->limit-1;
306 /* Calculate permute[]. Concurrently, initialize
307 * temp[] and limit[]. */
308 pp = 0;
309 for (i = minLen; i <= maxLen; i++) {
310 temp[i] = limit[i] = 0;
311 for (t = 0; t < symCount; t++)
312 if (length[t] == i)
313 hufGroup->permute[pp++] = t;
314 }
315 /* Count symbols coded for at each bit length */
316 for (i = 0; i < symCount; i++)
317 temp[length[i]]++;
318 /* Calculate limit[] (the largest symbol-coding value
319 *at each bit length, which is (previous limit <<
320 *1)+symbols at this level), and base[] (number of
321 *symbols to ignore at each bit length, which is limit
322 *minus the cumulative count of symbols coded for
323 *already). */
324 pp = t = 0;
325 for (i = minLen; i < maxLen; i++) {
326 pp += temp[i];
327 /* We read the largest possible symbol size
328 and then unget bits after determining how
329 many we need, and those extra bits could be
330 set to anything. (They're noise from
331 future symbols.) At each level we're
332 really only interested in the first few
333 bits, so here we set all the trailing
334 to-be-ignored bits to 1 so they don't
335 affect the value > limit[length]
336 comparison. */
337 limit[i] = (pp << (maxLen - i)) - 1;
338 pp <<= 1;
339 base[i+1] = pp-(t += temp[i]);
340 }
341 limit[maxLen+1] = INT_MAX; /* Sentinel value for
342 * reading next sym. */
343 limit[maxLen] = pp+temp[maxLen]-1;
344 base[minLen] = 0;
345 }
346 /* We've finished reading and digesting the block header. Now
347 read this block's Huffman coded symbols from the file and
348 undo the Huffman coding and run length encoding, saving the
349 result into dbuf[dbufCount++] = uc */
350
351 /* Initialize symbol occurrence counters and symbol Move To
352 * Front table */
353 for (i = 0; i < 256; i++) {
354 byteCount[i] = 0;
355 mtfSymbol[i] = (unsigned char)i;
356 }
357 /* Loop through compressed symbols. */
358 runPos = dbufCount = symCount = selector = 0;
359 for (;;) {
360 /* Determine which Huffman coding group to use. */
361 if (!(symCount--)) {
362 symCount = GROUP_SIZE-1;
363 if (selector >= nSelectors)
364 return RETVAL_DATA_ERROR;
365 hufGroup = bd->groups+selectors[selector++];
366 base = hufGroup->base-1;
367 limit = hufGroup->limit-1;
368 }
369 /* Read next Huffman-coded symbol. */
370 /* Note: It is far cheaper to read maxLen bits and
371 back up than it is to read minLen bits and then an
372 additional bit at a time, testing as we go.
373 Because there is a trailing last block (with file
374 CRC), there is no danger of the overread causing an
375 unexpected EOF for a valid compressed file. As a
376 further optimization, we do the read inline
377 (falling back to a call to get_bits if the buffer
378 runs dry). The following (up to got_huff_bits:) is
379 equivalent to j = get_bits(bd, hufGroup->maxLen);
380 */
381 while (bd->inbufBitCount < hufGroup->maxLen) {
382 if (bd->inbufPos == bd->inbufCount) {
383 j = get_bits(bd, hufGroup->maxLen);
384 goto got_huff_bits;
385 }
386 bd->inbufBits =
387 (bd->inbufBits << 8)|bd->inbuf[bd->inbufPos++];
388 bd->inbufBitCount += 8;
389 }
390 bd->inbufBitCount -= hufGroup->maxLen;
391 j = (bd->inbufBits >> bd->inbufBitCount)&
392 ((1 << hufGroup->maxLen)-1);
393 got_huff_bits:
394 /* Figure how many bits are in next symbol and
395 * unget extras */
396 i = hufGroup->minLen;
397 while (j > limit[i])
398 ++i;
399 bd->inbufBitCount += (hufGroup->maxLen - i);
400 /* Huffman decode value to get nextSym (with bounds checking) */
401 if ((i > hufGroup->maxLen)
402 || (((unsigned)(j = (j>>(hufGroup->maxLen-i))-base[i]))
403 >= MAX_SYMBOLS))
404 return RETVAL_DATA_ERROR;
405 nextSym = hufGroup->permute[j];
406 /* We have now decoded the symbol, which indicates
407 either a new literal byte, or a repeated run of the
408 most recent literal byte. First, check if nextSym
409 indicates a repeated run, and if so loop collecting
410 how many times to repeat the last literal. */
411 if (((unsigned)nextSym) <= SYMBOL_RUNB) { /* RUNA or RUNB */
412 /* If this is the start of a new run, zero out
413 * counter */
414 if (!runPos) {
415 runPos = 1;
416 t = 0;
417 }
418 /* Neat trick that saves 1 symbol: instead of
419 or-ing 0 or 1 at each bit position, add 1
420 or 2 instead. For example, 1011 is 1 << 0
421 + 1 << 1 + 2 << 2. 1010 is 2 << 0 + 2 << 1
422 + 1 << 2. You can make any bit pattern
423 that way using 1 less symbol than the basic
424 or 0/1 method (except all bits 0, which
425 would use no symbols, but a run of length 0
426 doesn't mean anything in this context).
427 Thus space is saved. */
428 t += (runPos << nextSym);
429 /* +runPos if RUNA; +2*runPos if RUNB */
430
431 runPos <<= 1;
432 continue;
433 }
434 /* When we hit the first non-run symbol after a run,
435 we now know how many times to repeat the last
436 literal, so append that many copies to our buffer
437 of decoded symbols (dbuf) now. (The last literal
438 used is the one at the head of the mtfSymbol
439 array.) */
440 if (runPos) {
441 runPos = 0;
442 if (dbufCount+t >= dbufSize)
443 return RETVAL_DATA_ERROR;
444
445 uc = symToByte[mtfSymbol[0]];
446 byteCount[uc] += t;
447 while (t--)
448 dbuf[dbufCount++] = uc;
449 }
450 /* Is this the terminating symbol? */
451 if (nextSym > symTotal)
452 break;
453 /* At this point, nextSym indicates a new literal
454 character. Subtract one to get the position in the
455 MTF array at which this literal is currently to be
456 found. (Note that the result can't be -1 or 0,
457 because 0 and 1 are RUNA and RUNB. But another
458 instance of the first symbol in the mtf array,
459 position 0, would have been handled as part of a
460 run above. Therefore 1 unused mtf position minus 2
461 non-literal nextSym values equals -1.) */
462 if (dbufCount >= dbufSize)
463 return RETVAL_DATA_ERROR;
464 i = nextSym - 1;
465 uc = mtfSymbol[i];
466 /* Adjust the MTF array. Since we typically expect to
467 *move only a small number of symbols, and are bound
468 *by 256 in any case, using memmove here would
469 *typically be bigger and slower due to function call
470 *overhead and other assorted setup costs. */
471 do {
472 mtfSymbol[i] = mtfSymbol[i-1];
473 } while (--i);
474 mtfSymbol[0] = uc;
475 uc = symToByte[uc];
476 /* We have our literal byte. Save it into dbuf. */
477 byteCount[uc]++;
478 dbuf[dbufCount++] = (unsigned int)uc;
479 }
480 /* At this point, we've read all the Huffman-coded symbols
481 (and repeated runs) for this block from the input stream,
482 and decoded them into the intermediate buffer. There are
483 dbufCount many decoded bytes in dbuf[]. Now undo the
484 Burrows-Wheeler transform on dbuf. See
485 http://dogma.net/markn/articles/bwt/bwt.htm
486 */
487 /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */
488 j = 0;
489 for (i = 0; i < 256; i++) {
490 k = j+byteCount[i];
491 byteCount[i] = j;
492 j = k;
493 }
494 /* Figure out what order dbuf would be in if we sorted it. */
495 for (i = 0; i < dbufCount; i++) {
496 uc = (unsigned char)(dbuf[i] & 0xff);
497 dbuf[byteCount[uc]] |= (i << 8);
498 byteCount[uc]++;
499 }
500 /* Decode first byte by hand to initialize "previous" byte.
501 Note that it doesn't get output, and if the first three
502 characters are identical it doesn't qualify as a run (hence
503 writeRunCountdown = 5). */
504 if (dbufCount) {
505 if (origPtr >= dbufCount)
506 return RETVAL_DATA_ERROR;
507 bd->writePos = dbuf[origPtr];
508 bd->writeCurrent = (unsigned char)(bd->writePos&0xff);
509 bd->writePos >>= 8;
510 bd->writeRunCountdown = 5;
511 }
512 bd->writeCount = dbufCount;
513
514 return RETVAL_OK;
515 }
516
517 /* Undo burrows-wheeler transform on intermediate buffer to produce output.
518 If start_bunzip was initialized with out_fd =-1, then up to len bytes of
519 data are written to outbuf. Return value is number of bytes written or
520 error (all errors are negative numbers). If out_fd!=-1, outbuf and len
521 are ignored, data is written to out_fd and return is RETVAL_OK or error.
522 */
523
524 static int INIT read_bunzip(struct bunzip_data *bd, char *outbuf, int len)
525 {
526 const unsigned int *dbuf;
527 int pos, xcurrent, previous, gotcount;
528
529 /* If last read was short due to end of file, return last block now */
530 if (bd->writeCount < 0)
531 return bd->writeCount;
532
533 gotcount = 0;
534 dbuf = bd->dbuf;
535 pos = bd->writePos;
536 xcurrent = bd->writeCurrent;
537
538 /* We will always have pending decoded data to write into the output
539 buffer unless this is the very first call (in which case we haven't
540 Huffman-decoded a block into the intermediate buffer yet). */
541
542 if (bd->writeCopies) {
543 /* Inside the loop, writeCopies means extra copies (beyond 1) */
544 --bd->writeCopies;
545 /* Loop outputting bytes */
546 for (;;) {
547 /* If the output buffer is full, snapshot
548 * state and return */
549 if (gotcount >= len) {
550 bd->writePos = pos;
551 bd->writeCurrent = xcurrent;
552 bd->writeCopies++;
553 return len;
554 }
555 /* Write next byte into output buffer, updating CRC */
556 outbuf[gotcount++] = xcurrent;
557 bd->writeCRC = (((bd->writeCRC) << 8)
558 ^bd->crc32Table[((bd->writeCRC) >> 24)
559 ^xcurrent]);
560 /* Loop now if we're outputting multiple
561 * copies of this byte */
562 if (bd->writeCopies) {
563 --bd->writeCopies;
564 continue;
565 }
566 decode_next_byte:
567 if (!bd->writeCount--)
568 break;
569 /* Follow sequence vector to undo
570 * Burrows-Wheeler transform */
571 previous = xcurrent;
572 pos = dbuf[pos];
573 xcurrent = pos&0xff;
574 pos >>= 8;
575 /* After 3 consecutive copies of the same
576 byte, the 4th is a repeat count. We count
577 down from 4 instead *of counting up because
578 testing for non-zero is faster */
579 if (--bd->writeRunCountdown) {
580 if (xcurrent != previous)
581 bd->writeRunCountdown = 4;
582 } else {
583 /* We have a repeated run, this byte
584 * indicates the count */
585 bd->writeCopies = xcurrent;
586 xcurrent = previous;
587 bd->writeRunCountdown = 5;
588 /* Sometimes there are just 3 bytes
589 * (run length 0) */
590 if (!bd->writeCopies)
591 goto decode_next_byte;
592 /* Subtract the 1 copy we'd output
593 * anyway to get extras */
594 --bd->writeCopies;
595 }
596 }
597 /* Decompression of this block completed successfully */
598 bd->writeCRC = ~bd->writeCRC;
599 bd->totalCRC = ((bd->totalCRC << 1) |
600 (bd->totalCRC >> 31)) ^ bd->writeCRC;
601 /* If this block had a CRC error, force file level CRC error. */
602 if (bd->writeCRC != bd->headerCRC) {
603 bd->totalCRC = bd->headerCRC+1;
604 return RETVAL_LAST_BLOCK;
605 }
606 }
607
608 /* Refill the intermediate buffer by Huffman-decoding next
609 * block of input */
610 /* (previous is just a convenient unused temp variable here) */
611 previous = get_next_block(bd);
612 if (previous) {
613 bd->writeCount = previous;
614 return (previous != RETVAL_LAST_BLOCK) ? previous : gotcount;
615 }
616 bd->writeCRC = 0xffffffffUL;
617 pos = bd->writePos;
618 xcurrent = bd->writeCurrent;
619 goto decode_next_byte;
620 }
621
622 static long INIT nofill(void *buf, unsigned long len)
623 {
624 return -1;
625 }
626
627 /* Allocate the structure, read file header. If in_fd ==-1, inbuf must contain
628 a complete bunzip file (len bytes long). If in_fd!=-1, inbuf and len are
629 ignored, and data is read from file handle into temporary buffer. */
630 static int INIT start_bunzip(struct bunzip_data **bdp, void *inbuf, long len,
631 long (*fill)(void*, unsigned long))
632 {
633 struct bunzip_data *bd;
634 unsigned int i, j, c;
635 const unsigned int BZh0 =
636 (((unsigned int)'B') << 24)+(((unsigned int)'Z') << 16)
637 +(((unsigned int)'h') << 8)+(unsigned int)'';
638
639 /* Figure out how much data to allocate */
640 i = sizeof(struct bunzip_data);
641
642 /* Allocate bunzip_data. Most fields initialize to zero. */
643 bd = *bdp = malloc(i);
644 if (!bd)
645 return RETVAL_OUT_OF_MEMORY;
646 memset(bd, 0, sizeof(struct bunzip_data));
647 /* Setup input buffer */
648 bd->inbuf = inbuf;
649 bd->inbufCount = len;
650 if (fill != NULL)
651 bd->fill = fill;
652 else
653 bd->fill = nofill;
654
655 /* Init the CRC32 table (big endian) */
656 for (i = 0; i < 256; i++) {
657 c = i << 24;
658 for (j = 8; j; j--)
659 c = c&0x80000000 ? (c << 1)^(CRC32_POLY_BE) : (c << 1);
660 bd->crc32Table[i] = c;
661 }
662
663 /* Ensure that file starts with "BZh['1'-'9']." */
664 i = get_bits(bd, 32);
665 if (((unsigned int)(i-BZh0-1)) >= 9)
666 return RETVAL_NOT_BZIP_DATA;
667
668 /* Fourth byte (ascii '1'-'9'), indicates block size in units of 100k of
669 uncompressed data. Allocate intermediate buffer for block. */
670 bd->dbufSize = 100000*(i-BZh0);
671
672 bd->dbuf = large_malloc(bd->dbufSize * sizeof(int));
673 if (!bd->dbuf)
674 return RETVAL_OUT_OF_MEMORY;
675 return RETVAL_OK;
676 }
677
678 /* Example usage: decompress src_fd to dst_fd. (Stops at end of bzip2 data,
679 not end of file.) */
680 STATIC int INIT bunzip2(unsigned char *buf, long len,
681 long (*fill)(void*, unsigned long),
682 long (*flush)(void*, unsigned long),
683 unsigned char *outbuf,
684 long *pos,
685 void(*error)(char *x))
686 {
687 struct bunzip_data *bd;
688 int i = -1;
689 unsigned char *inbuf;
690
691 if (flush)
692 outbuf = malloc(BZIP2_IOBUF_SIZE);
693
694 if (!outbuf) {
695 error("Could not allocate output buffer");
696 return RETVAL_OUT_OF_MEMORY;
697 }
698 if (buf)
699 inbuf = buf;
700 else
701 inbuf = malloc(BZIP2_IOBUF_SIZE);
702 if (!inbuf) {
703 error("Could not allocate input buffer");
704 i = RETVAL_OUT_OF_MEMORY;
705 goto exit_0;
706 }
707 i = start_bunzip(&bd, inbuf, len, fill);
708 if (!i) {
709 for (;;) {
710 i = read_bunzip(bd, outbuf, BZIP2_IOBUF_SIZE);
711 if (i <= 0)
712 break;
713 if (!flush)
714 outbuf += i;
715 else
716 if (i != flush(outbuf, i)) {
717 i = RETVAL_UNEXPECTED_OUTPUT_EOF;
718 break;
719 }
720 }
721 }
722 /* Check CRC and release memory */
723 if (i == RETVAL_LAST_BLOCK) {
724 if (bd->headerCRC != bd->totalCRC)
725 error("Data integrity error when decompressing.");
726 else
727 i = RETVAL_OK;
728 } else if (i == RETVAL_UNEXPECTED_OUTPUT_EOF) {
729 error("Compressed file ends unexpectedly");
730 }
731 if (!bd)
732 goto exit_1;
733 if (bd->dbuf)
734 large_free(bd->dbuf);
735 if (pos)
736 *pos = bd->inbufPos;
737 free(bd);
738 exit_1:
739 if (!buf)
740 free(inbuf);
741 exit_0:
742 if (flush)
743 free(outbuf);
744 return i;
745 }
746
747 #ifdef PREBOOT
748 STATIC int INIT __decompress(unsigned char *buf, long len,
749 long (*fill)(void*, unsigned long),
750 long (*flush)(void*, unsigned long),
751 unsigned char *outbuf, long olen,
752 long *pos,
753 void (*error)(char *x))
754 {
755 return bunzip2(buf, len - 4, fill, flush, outbuf, pos, error);
756 }
757 #endif
758
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