1 /* vi: set sw=4 ts=4: */
2 /* Small bzip2 deflate implementation, by Rob Landley (rob@landley.net).
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.
9 Licensed under GPLv2 or later, see file LICENSE in this source tree.
13 Size and speed optimizations by Manuel Novoa III (mjn3@codepoet.org).
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.
19 Note that about 2/3 of the time is spent in read_bunzip() reversing
20 the Burrows-Wheeler transformation. Much of that time is delay
21 resulting from cache misses.
23 (2010 update by vda: profiled "bzcat <84mbyte.bz2 >/dev/null"
24 on x86-64 CPU with L2 > 1M: get_next_block is hotter than read_bunzip:
25 %time seconds calls function
26 71.01 12.69 444 get_next_block
27 28.65 5.12 93065 read_bunzip
28 00.22 0.04 7736490 get_bits
29 00.11 0.02 47 dealloc_bunzip
30 00.00 0.00 93018 full_write
34 I would ask that anyone benefiting from this work, especially those
35 using it in commercial products, consider making a donation to my local
36 non-profit hospice organization (www.hospiceacadiana.com) in the name of
37 the woman I loved, Toni W. Hagan, who passed away Feb. 12, 2003.
43 #include "bb_archive.h"
46 # define dbg(...) bb_error_msg(__VA_ARGS__)
48 # define dbg(...) ((void)0)
51 /* Constants for Huffman coding */
53 #define GROUP_SIZE 50 /* 64 would have been more efficient */
54 #define MAX_HUFCODE_BITS 20 /* Longest Huffman code allowed */
55 #define MAX_SYMBOLS 258 /* 256 literals + RUNA + RUNB */
59 /* Status return values */
61 #define RETVAL_LAST_BLOCK (dbg("%d", __LINE__), -1)
62 #define RETVAL_NOT_BZIP_DATA (dbg("%d", __LINE__), -2)
63 #define RETVAL_UNEXPECTED_INPUT_EOF (dbg("%d", __LINE__), -3)
64 #define RETVAL_SHORT_WRITE (dbg("%d", __LINE__), -4)
65 #define RETVAL_DATA_ERROR (dbg("%d", __LINE__), -5)
66 #define RETVAL_OUT_OF_MEMORY (dbg("%d", __LINE__), -6)
67 #define RETVAL_OBSOLETE_INPUT (dbg("%d", __LINE__), -7)
69 /* Other housekeeping constants */
70 #define IOBUF_SIZE 4096
72 /* This is what we know about each Huffman coding group */
74 /* We have an extra slot at the end of limit[] for a sentinel value. */
75 int limit[MAX_HUFCODE_BITS+1], base[MAX_HUFCODE_BITS], permute[MAX_SYMBOLS];
79 /* Structure holding all the housekeeping data, including IO buffers and
80 * memory that persists between calls to bunzip
81 * Found the most used member:
82 * cat this_file.c | sed -e 's/"/ /g' -e "s/'/ /g" | xargs -n1 \
83 * | grep 'bd->' | sed 's/^.*bd->/bd->/' | sort | $PAGER
84 * and moved it (inbufBitCount) to offset 0.
87 /* I/O tracking data (file handles, buffers, positions, etc.) */
88 unsigned inbufBitCount, inbufBits;
89 int in_fd, out_fd, inbufCount, inbufPos /*, outbufPos*/;
90 uint8_t *inbuf /*,*outbuf*/;
92 /* State for interrupting output loop */
93 int writeCopies, writePos, writeRunCountdown, writeCount;
94 int writeCurrent; /* actually a uint8_t */
96 /* The CRC values stored in the block header and calculated from the data */
97 uint32_t headerCRC, totalCRC, writeCRC;
99 /* Intermediate buffer and its size (in bytes) */
103 /* For I/O error handling */
106 /* Big things go last (register-relative addressing can be larger for big offsets) */
107 uint32_t crc32Table[256];
108 uint8_t selectors[32768]; /* nSelectors=15 bits */
109 struct group_data groups[MAX_GROUPS]; /* Huffman coding tables */
111 /* typedef struct bunzip_data bunzip_data; -- done in .h file */
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 get_bits(bunzip_data *bd, int bits_wanted)
119 /* Cache bd->inbufBitCount in a CPU register (hopefully): */
120 int bit_count = bd->inbufBitCount;
122 /* If we need to get more data from the byte buffer, do so. (Loop getting
123 one byte at a time to enforce endianness and avoid unaligned access.) */
124 while (bit_count < bits_wanted) {
126 /* If we need to read more data from file into byte buffer, do so */
127 if (bd->inbufPos == bd->inbufCount) {
128 /* if "no input fd" case: in_fd == -1, read fails, we jump */
129 bd->inbufCount = read(bd->in_fd, bd->inbuf, IOBUF_SIZE);
130 if (bd->inbufCount <= 0)
131 longjmp(bd->jmpbuf, RETVAL_UNEXPECTED_INPUT_EOF);
135 /* Avoid 32-bit overflow (dump bit buffer to top of output) */
136 if (bit_count >= 24) {
137 bits = bd->inbufBits & ((1 << bit_count) - 1);
138 bits_wanted -= bit_count;
139 bits <<= bits_wanted;
143 /* Grab next 8 bits of input from buffer. */
144 bd->inbufBits = (bd->inbufBits << 8) | bd->inbuf[bd->inbufPos++];
148 /* Calculate result */
149 bit_count -= bits_wanted;
150 bd->inbufBitCount = bit_count;
151 bits |= (bd->inbufBits >> bit_count) & ((1 << bits_wanted) - 1);
156 /* Unpacks the next block and sets up for the inverse Burrows-Wheeler step. */
157 static int get_next_block(bunzip_data *bd)
159 struct group_data *hufGroup;
160 int dbufCount, dbufSize, groupCount, *base, *limit, selector,
161 i, j, t, runPos, symCount, symTotal, nSelectors, byteCount[256];
162 int runCnt = runCnt; /* for compiler */
163 uint8_t uc, symToByte[256], mtfSymbol[256], *selectors;
168 dbufSize = bd->dbufSize;
169 selectors = bd->selectors;
171 /* In bbox, we are ok with aborting through setjmp which is set up in start_bunzip */
173 /* Reset longjmp I/O error handling */
174 i = setjmp(bd->jmpbuf);
178 /* Read in header signature and CRC, then validate signature.
179 (last block signature means CRC is for whole file, return now) */
180 i = get_bits(bd, 24);
181 j = get_bits(bd, 24);
182 bd->headerCRC = get_bits(bd, 32);
183 if ((i == 0x177245) && (j == 0x385090)) return RETVAL_LAST_BLOCK;
184 if ((i != 0x314159) || (j != 0x265359)) return RETVAL_NOT_BZIP_DATA;
186 /* We can add support for blockRandomised if anybody complains. There was
187 some code for this in busybox 1.0.0-pre3, but nobody ever noticed that
188 it didn't actually work. */
189 if (get_bits(bd, 1)) return RETVAL_OBSOLETE_INPUT;
190 origPtr = get_bits(bd, 24);
191 if ((int)origPtr > dbufSize) return RETVAL_DATA_ERROR;
193 /* mapping table: if some byte values are never used (encoding things
194 like ascii text), the compression code removes the gaps to have fewer
195 symbols to deal with, and writes a sparse bitfield indicating which
196 values were present. We make a translation table to convert the symbols
197 back to the corresponding bytes. */
200 t = get_bits(bd, 16);
203 unsigned inner_map = get_bits(bd, 16);
205 if (inner_map & (1 << 15))
206 symToByte[symTotal++] = i;
216 /* How many different Huffman coding groups does this block use? */
217 groupCount = get_bits(bd, 3);
218 if (groupCount < 2 || groupCount > MAX_GROUPS)
219 return RETVAL_DATA_ERROR;
221 /* nSelectors: Every GROUP_SIZE many symbols we select a new Huffman coding
222 group. Read in the group selector list, which is stored as MTF encoded
223 bit runs. (MTF=Move To Front, as each value is used it's moved to the
224 start of the list.) */
225 for (i = 0; i < groupCount; i++)
227 nSelectors = get_bits(bd, 15);
229 return RETVAL_DATA_ERROR;
230 for (i = 0; i < nSelectors; i++) {
234 while (get_bits(bd, 1)) {
235 if (n >= groupCount) return RETVAL_DATA_ERROR;
238 /* Decode MTF to get the next selector */
239 tmp_byte = mtfSymbol[n];
241 mtfSymbol[n + 1] = mtfSymbol[n];
242 mtfSymbol[0] = selectors[i] = tmp_byte;
245 /* Read the Huffman coding tables for each group, which code for symTotal
246 literal symbols, plus two run symbols (RUNA, RUNB) */
247 symCount = symTotal + 2;
248 for (j = 0; j < groupCount; j++) {
249 uint8_t length[MAX_SYMBOLS];
250 /* 8 bits is ALMOST enough for temp[], see below */
251 unsigned temp[MAX_HUFCODE_BITS+1];
252 int minLen, maxLen, pp, len_m1;
254 /* Read Huffman code lengths for each symbol. They're stored in
255 a way similar to mtf; record a starting value for the first symbol,
256 and an offset from the previous value for every symbol after that.
257 (Subtracting 1 before the loop and then adding it back at the end is
258 an optimization that makes the test inside the loop simpler: symbol
259 length 0 becomes negative, so an unsigned inequality catches it.) */
260 len_m1 = get_bits(bd, 5) - 1;
261 for (i = 0; i < symCount; i++) {
264 if ((unsigned)len_m1 > (MAX_HUFCODE_BITS-1))
265 return RETVAL_DATA_ERROR;
267 /* If first bit is 0, stop. Else second bit indicates whether
268 to increment or decrement the value. Optimization: grab 2
269 bits and unget the second if the first was 0. */
270 two_bits = get_bits(bd, 2);
276 /* Add one if second bit 1, else subtract 1. Avoids if/else */
277 len_m1 += (((two_bits+1) & 2) - 1);
280 /* Correct for the initial -1, to get the final symbol length */
281 length[i] = len_m1 + 1;
284 /* Find largest and smallest lengths in this group */
285 minLen = maxLen = length[0];
286 for (i = 1; i < symCount; i++) {
287 if (length[i] > maxLen) maxLen = length[i];
288 else if (length[i] < minLen) minLen = length[i];
291 /* Calculate permute[], base[], and limit[] tables from length[].
293 * permute[] is the lookup table for converting Huffman coded symbols
294 * into decoded symbols. base[] is the amount to subtract from the
295 * value of a Huffman symbol of a given length when using permute[].
297 * limit[] indicates the largest numerical value a symbol with a given
298 * number of bits can have. This is how the Huffman codes can vary in
299 * length: each code with a value>limit[length] needs another bit.
301 hufGroup = bd->groups + j;
302 hufGroup->minLen = minLen;
303 hufGroup->maxLen = maxLen;
305 /* Note that minLen can't be smaller than 1, so we adjust the base
306 and limit array pointers so we're not always wasting the first
307 entry. We do this again when using them (during symbol decoding). */
308 base = hufGroup->base - 1;
309 limit = hufGroup->limit - 1;
311 /* Calculate permute[]. Concurently, initialize temp[] and limit[]. */
313 for (i = minLen; i <= maxLen; i++) {
315 temp[i] = limit[i] = 0;
316 for (k = 0; k < symCount; k++)
318 hufGroup->permute[pp++] = k;
321 /* Count symbols coded for at each bit length */
322 /* NB: in pathological cases, temp[8] can end ip being 256.
323 * That's why uint8_t is too small for temp[]. */
324 for (i = 0; i < symCount; i++) temp[length[i]]++;
326 /* Calculate limit[] (the largest symbol-coding value at each bit
327 * length, which is (previous limit<<1)+symbols at this level), and
328 * base[] (number of symbols to ignore at each bit length, which is
329 * limit minus the cumulative count of symbols coded for already). */
331 for (i = minLen; i < maxLen;) {
332 unsigned temp_i = temp[i];
336 /* We read the largest possible symbol size and then unget bits
337 after determining how many we need, and those extra bits could
338 be set to anything. (They're noise from future symbols.) At
339 each level we're really only interested in the first few bits,
340 so here we set all the trailing to-be-ignored bits to 1 so they
341 don't affect the value>limit[length] comparison. */
342 limit[i] = (pp << (maxLen - i)) - 1;
347 limit[maxLen] = pp + temp[maxLen] - 1;
348 limit[maxLen+1] = INT_MAX; /* Sentinel value for reading next sym. */
352 /* We've finished reading and digesting the block header. Now read this
353 block's Huffman coded symbols from the file and undo the Huffman coding
354 and run length encoding, saving the result into dbuf[dbufCount++] = uc */
356 /* Initialize symbol occurrence counters and symbol Move To Front table */
357 /*memset(byteCount, 0, sizeof(byteCount)); - smaller, but slower */
358 for (i = 0; i < 256; i++) {
360 mtfSymbol[i] = (uint8_t)i;
363 /* Loop through compressed symbols. */
365 runPos = dbufCount = selector = 0;
369 /* Fetch next Huffman coding group from list. */
370 symCount = GROUP_SIZE - 1;
371 if (selector >= nSelectors) return RETVAL_DATA_ERROR;
372 hufGroup = bd->groups + selectors[selector++];
373 base = hufGroup->base - 1;
374 limit = hufGroup->limit - 1;
377 /* Read next Huffman-coded symbol. */
379 /* Note: It is far cheaper to read maxLen bits and back up than it is
380 to read minLen bits and then add additional bit at a time, testing
381 as we go. Because there is a trailing last block (with file CRC),
382 there is no danger of the overread causing an unexpected EOF for a
383 valid compressed file.
386 /* As a further optimization, we do the read inline
387 (falling back to a call to get_bits if the buffer runs dry).
390 while ((new_cnt = bd->inbufBitCount - hufGroup->maxLen) < 0) {
391 /* bd->inbufBitCount < hufGroup->maxLen */
392 if (bd->inbufPos == bd->inbufCount) {
393 nextSym = get_bits(bd, hufGroup->maxLen);
396 bd->inbufBits = (bd->inbufBits << 8) | bd->inbuf[bd->inbufPos++];
397 bd->inbufBitCount += 8;
399 bd->inbufBitCount = new_cnt; /* "bd->inbufBitCount -= hufGroup->maxLen;" */
400 nextSym = (bd->inbufBits >> new_cnt) & ((1 << hufGroup->maxLen) - 1);
402 } else { /* unoptimized equivalent */
403 nextSym = get_bits(bd, hufGroup->maxLen);
405 /* Figure how many bits are in next symbol and unget extras */
406 i = hufGroup->minLen;
407 while (nextSym > limit[i]) ++i;
408 j = hufGroup->maxLen - i;
410 return RETVAL_DATA_ERROR;
411 bd->inbufBitCount += j;
413 /* Huffman decode value to get nextSym (with bounds checking) */
414 nextSym = (nextSym >> j) - base[i];
415 if ((unsigned)nextSym >= MAX_SYMBOLS)
416 return RETVAL_DATA_ERROR;
417 nextSym = hufGroup->permute[nextSym];
419 /* We have now decoded the symbol, which indicates either a new literal
420 byte, or a repeated run of the most recent literal byte. First,
421 check if nextSym indicates a repeated run, and if so loop collecting
422 how many times to repeat the last literal. */
423 if ((unsigned)nextSym <= SYMBOL_RUNB) { /* RUNA or RUNB */
425 /* If this is the start of a new run, zero out counter */
431 /* Neat trick that saves 1 symbol: instead of or-ing 0 or 1 at
432 each bit position, add 1 or 2 instead. For example,
433 1011 is 1<<0 + 1<<1 + 2<<2. 1010 is 2<<0 + 2<<1 + 1<<2.
434 You can make any bit pattern that way using 1 less symbol than
435 the basic or 0/1 method (except all bits 0, which would use no
436 symbols, but a run of length 0 doesn't mean anything in this
437 context). Thus space is saved. */
438 runCnt += (runPos << nextSym); /* +runPos if RUNA; +2*runPos if RUNB */
439 if (runPos < dbufSize) runPos <<= 1;
440 goto end_of_huffman_loop;
443 /* When we hit the first non-run symbol after a run, we now know
444 how many times to repeat the last literal, so append that many
445 copies to our buffer of decoded symbols (dbuf) now. (The last
446 literal used is the one at the head of the mtfSymbol array.) */
449 if (dbufCount + runCnt > dbufSize) {
450 dbg("dbufCount:%d+runCnt:%d %d > dbufSize:%d RETVAL_DATA_ERROR",
451 dbufCount, runCnt, dbufCount + runCnt, dbufSize);
452 return RETVAL_DATA_ERROR;
454 tmp_byte = symToByte[mtfSymbol[0]];
455 byteCount[tmp_byte] += runCnt;
456 while (--runCnt >= 0) dbuf[dbufCount++] = (uint32_t)tmp_byte;
460 /* Is this the terminating symbol? */
461 if (nextSym > symTotal) break;
463 /* At this point, nextSym indicates a new literal character. Subtract
464 one to get the position in the MTF array at which this literal is
465 currently to be found. (Note that the result can't be -1 or 0,
466 because 0 and 1 are RUNA and RUNB. But another instance of the
467 first symbol in the mtf array, position 0, would have been handled
468 as part of a run above. Therefore 1 unused mtf position minus
469 2 non-literal nextSym values equals -1.) */
470 if (dbufCount >= dbufSize) return RETVAL_DATA_ERROR;
474 /* Adjust the MTF array. Since we typically expect to move only a
475 * small number of symbols, and are bound by 256 in any case, using
476 * memmove here would typically be bigger and slower due to function
477 * call overhead and other assorted setup costs. */
479 mtfSymbol[i] = mtfSymbol[i-1];
484 /* We have our literal byte. Save it into dbuf. */
486 dbuf[dbufCount++] = (uint32_t)uc;
488 /* Skip group initialization if we're not done with this group. Done
489 * this way to avoid compiler warning. */
491 if (--symCount >= 0) goto continue_this_group;
494 /* At this point, we've read all the Huffman-coded symbols (and repeated
495 runs) for this block from the input stream, and decoded them into the
496 intermediate buffer. There are dbufCount many decoded bytes in dbuf[].
497 Now undo the Burrows-Wheeler transform on dbuf.
498 See http://dogma.net/markn/articles/bwt/bwt.htm
501 /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */
503 for (i = 0; i < 256; i++) {
504 int tmp_count = j + byteCount[i];
509 /* Figure out what order dbuf would be in if we sorted it. */
510 for (i = 0; i < dbufCount; i++) {
511 uint8_t tmp_byte = (uint8_t)dbuf[i];
512 int tmp_count = byteCount[tmp_byte];
513 dbuf[tmp_count] |= (i << 8);
514 byteCount[tmp_byte] = tmp_count + 1;
517 /* Decode first byte by hand to initialize "previous" byte. Note that it
518 doesn't get output, and if the first three characters are identical
519 it doesn't qualify as a run (hence writeRunCountdown=5). */
522 if ((int)origPtr >= dbufCount) return RETVAL_DATA_ERROR;
524 bd->writeCurrent = (uint8_t)tmp;
525 bd->writePos = (tmp >> 8);
526 bd->writeRunCountdown = 5;
528 bd->writeCount = dbufCount;
533 /* Undo Burrows-Wheeler transform on intermediate buffer to produce output.
534 If start_bunzip was initialized with out_fd=-1, then up to len bytes of
535 data are written to outbuf. Return value is number of bytes written or
536 error (all errors are negative numbers). If out_fd!=-1, outbuf and len
537 are ignored, data is written to out_fd and return is RETVAL_OK or error.
539 NB: read_bunzip returns < 0 on error, or the number of *unfilled* bytes
540 in outbuf. IOW: on EOF returns len ("all bytes are not filled"), not 0.
541 (Why? This allows to get rid of one local variable)
543 int FAST_FUNC read_bunzip(bunzip_data *bd, char *outbuf, int len)
545 const uint32_t *dbuf;
546 int pos, current, previous;
549 /* If we already have error/end indicator, return it */
550 if (bd->writeCount < 0)
551 return bd->writeCount;
555 /* Register-cached state (hopefully): */
557 current = bd->writeCurrent;
558 CRC = bd->writeCRC; /* small loss on x86-32 (not enough regs), win on x86-64 */
560 /* We will always have pending decoded data to write into the output
561 buffer unless this is the very first call (in which case we haven't
562 Huffman-decoded a block into the intermediate buffer yet). */
563 if (bd->writeCopies) {
566 /* Inside the loop, writeCopies means extra copies (beyond 1) */
569 /* Loop outputting bytes */
572 /* If the output buffer is full, save cached state and return */
575 * Use of "goto" instead of keeping code here
576 * helps compiler to realize this. */
580 /* Write next byte into output buffer, updating CRC */
582 CRC = (CRC << 8) ^ bd->crc32Table[(CRC >> 24) ^ current];
584 /* Loop now if we're outputting multiple copies of this byte */
585 if (bd->writeCopies) {
586 /* Unlikely branch */
587 /*--bd->writeCopies;*/
589 /* Same, but (ab)using other existing --writeCopies operation
590 * (and this if() compiles into just test+branch pair): */
591 goto dec_writeCopies;
594 if (--bd->writeCount < 0)
595 break; /* input block is fully consumed, need next one */
597 /* Follow sequence vector to undo Burrows-Wheeler transform */
600 current = (uint8_t)pos;
603 /* After 3 consecutive copies of the same byte, the 4th
604 * is a repeat count. We count down from 4 instead
605 * of counting up because testing for non-zero is faster */
606 if (--bd->writeRunCountdown != 0) {
607 if (current != previous)
608 bd->writeRunCountdown = 4;
610 /* Unlikely branch */
611 /* We have a repeated run, this byte indicates the count */
612 bd->writeCopies = current;
614 bd->writeRunCountdown = 5;
616 /* Sometimes there are just 3 bytes (run length 0) */
617 if (!bd->writeCopies) goto decode_next_byte;
619 /* Subtract the 1 copy we'd output anyway to get extras */
624 /* Decompression of this input block completed successfully */
625 bd->writeCRC = CRC = ~CRC;
626 bd->totalCRC = ((bd->totalCRC << 1) | (bd->totalCRC >> 31)) ^ CRC;
628 /* If this block had a CRC error, force file level CRC error */
629 if (CRC != bd->headerCRC) {
630 bd->totalCRC = bd->headerCRC + 1;
631 return RETVAL_LAST_BLOCK;
635 /* Refill the intermediate buffer by Huffman-decoding next block of input */
637 int r = get_next_block(bd);
638 if (r) { /* error/end */
640 return (r != RETVAL_LAST_BLOCK) ? r : len;
646 current = bd->writeCurrent;
647 goto decode_next_byte;
650 /* Output buffer is full, save cached state and return */
652 bd->writeCurrent = current;
660 /* Allocate the structure, read file header. If in_fd==-1, inbuf must contain
661 a complete bunzip file (len bytes long). If in_fd!=-1, inbuf and len are
662 ignored, and data is read from file handle into temporary buffer. */
664 /* Because bunzip2 is used for help text unpacking, and because bb_show_usage()
665 should work for NOFORK applets too, we must be extremely careful to not leak
667 int FAST_FUNC start_bunzip(bunzip_data **bdp, int in_fd,
668 const void *inbuf, int len)
673 BZh0 = ('B' << 24) + ('Z' << 16) + ('h' << 8) + '0',
674 h0 = ('h' << 8) + '0',
677 /* Figure out how much data to allocate */
678 i = sizeof(bunzip_data);
679 if (in_fd != -1) i += IOBUF_SIZE;
681 /* Allocate bunzip_data. Most fields initialize to zero. */
682 bd = *bdp = xzalloc(i);
684 /* Setup input buffer */
687 /* in this case, bd->inbuf is read-only */
688 bd->inbuf = (void*)inbuf; /* cast away const-ness */
690 bd->inbuf = (uint8_t*)(bd + 1);
691 memcpy(bd->inbuf, inbuf, len);
693 bd->inbufCount = len;
695 /* Init the CRC32 table (big endian) */
696 crc32_filltable(bd->crc32Table, 1);
698 /* Setup for I/O error handling via longjmp */
699 i = setjmp(bd->jmpbuf);
702 /* Ensure that file starts with "BZh['1'-'9']." */
703 /* Update: now caller verifies 1st two bytes, makes .gz/.bz2
704 * integration easier */
706 /* i = get_bits(bd, 32); */
707 /* if ((unsigned)(i - BZh0 - 1) >= 9) return RETVAL_NOT_BZIP_DATA; */
708 i = get_bits(bd, 16);
709 if ((unsigned)(i - h0 - 1) >= 9) return RETVAL_NOT_BZIP_DATA;
711 /* Fourth byte (ascii '1'-'9') indicates block size in units of 100k of
712 uncompressed data. Allocate intermediate buffer for block. */
713 /* bd->dbufSize = 100000 * (i - BZh0); */
714 bd->dbufSize = 100000 * (i - h0);
716 /* Cannot use xmalloc - may leak bd in NOFORK case! */
717 bd->dbuf = malloc_or_warn(bd->dbufSize * sizeof(bd->dbuf[0]));
725 void FAST_FUNC dealloc_bunzip(bunzip_data *bd)
732 /* Decompress src_fd to dst_fd. Stops at end of bzip data, not end of file. */
733 IF_DESKTOP(long long) int FAST_FUNC
734 unpack_bz2_stream(transformer_aux_data_t *aux, int src_fd, int dst_fd)
736 IF_DESKTOP(long long total_written = 0;)
742 if (check_signature16(aux, src_fd, BZIP2_MAGIC))
745 outbuf = xmalloc(IOBUF_SIZE);
747 while (1) { /* "Process one BZ... stream" loop */
749 i = start_bunzip(&bd, src_fd, outbuf + 2, len);
752 while (1) { /* "Produce some output bytes" loop */
753 i = read_bunzip(bd, outbuf, IOBUF_SIZE);
754 if (i < 0) /* error? */
756 i = IOBUF_SIZE - i; /* number of bytes produced */
757 if (i == 0) /* EOF? */
759 if (i != full_write(dst_fd, outbuf, i)) {
760 bb_error_msg("short write");
761 i = RETVAL_SHORT_WRITE;
764 IF_DESKTOP(total_written += i;)
768 if (i != RETVAL_LAST_BLOCK
769 /* Observed case when i == RETVAL_OK:
770 * "bzcat z.bz2", where "z.bz2" is a bzipped zero-length file
771 * (to be exact, z.bz2 is exactly these 14 bytes:
772 * 42 5a 68 39 17 72 45 38 50 90 00 00 00 00).
776 bb_error_msg("bunzip error %d", i);
779 if (bd->headerCRC != bd->totalCRC) {
780 bb_error_msg("CRC error");
784 /* Successfully unpacked one BZ stream */
787 /* Do we have "BZ..." after last processed byte?
788 * pbzip2 (parallelized bzip2) produces such files.
790 len = bd->inbufCount - bd->inbufPos;
791 memcpy(outbuf, &bd->inbuf[bd->inbufPos], len);
793 if (safe_read(src_fd, outbuf + len, 2 - len) != 2 - len)
797 if (*(uint16_t*)outbuf != BZIP2_MAGIC) /* "BZ"? */
807 return i ? i : IF_DESKTOP(total_written) + 0;
812 static char *const bunzip_errors[] = {
813 NULL, "Bad file checksum", "Not bzip data",
814 "Unexpected input EOF", "Unexpected output EOF", "Data error",
815 "Out of memory", "Obsolete (pre 0.9.5) bzip format not supported"
818 /* Dumb little test thing, decompress stdin to stdout */
819 int main(int argc, char **argv)
823 int i = unpack_bz2_stream(0, 1);
825 fprintf(stderr, "%s\n", bunzip_errors[-i]);
826 else if (read(STDIN_FILENO, &c, 1))
827 fprintf(stderr, "Trailing garbage ignored\n");