1 /* vi: set sw=4 ts=4: */
2 /*
3 * Small bzip2 deflate implementation, by Rob Landley (rob@landley.net).
4 *
5 * Based on bzip2 decompression code by Julian R Seward (jseward@acm.org),
6 * which also acknowledges contributions by Mike Burrows, David Wheeler,
7 * Peter Fenwick, Alistair Moffat, Radford Neal, Ian H. Witten,
8 * Robert Sedgewick, and Jon L. Bentley.
9 *
10 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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_bunzip() reversing
20 the Burrows-Wheeler transformation. Much of that time is delay
21 resulting from cache misses.
22
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
31 ...)
32
33
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.
38
39 Manuel
40 */
41 #include "libbb.h"
42 #include "bb_archive.h"
43
44 #if 0
45 # define dbg(...) bb_error_msg(__VA_ARGS__)
46 #else
47 # define dbg(...) ((void)0)
48 #endif
49
50 /* Constants for Huffman coding */
51 #define MAX_GROUPS 6
52 #define GROUP_SIZE 50 /* 64 would have been more efficient */
53 #define MAX_HUFCODE_BITS 20 /* Longest Huffman code allowed */
54 #define MAX_SYMBOLS 258 /* 256 literals + RUNA + RUNB */
55 #define SYMBOL_RUNA 0
56 #define SYMBOL_RUNB 1
57
58 /* Status return values */
59 #define RETVAL_OK 0
60 #define RETVAL_LAST_BLOCK (dbg("%d", __LINE__), -1)
61 #define RETVAL_NOT_BZIP_DATA (dbg("%d", __LINE__), -2)
62 #define RETVAL_UNEXPECTED_INPUT_EOF (dbg("%d", __LINE__), -3)
63 #define RETVAL_SHORT_WRITE (dbg("%d", __LINE__), -4)
64 #define RETVAL_DATA_ERROR (dbg("%d", __LINE__), -5)
65 #define RETVAL_OUT_OF_MEMORY (dbg("%d", __LINE__), -6)
66 #define RETVAL_OBSOLETE_INPUT (dbg("%d", __LINE__), -7)
67
68 /* Other housekeeping constants */
69 #define IOBUF_SIZE 4096
70
71 /* This is what we know about each Huffman coding group */
72 struct group_data {
73 /* We have an extra slot at the end of limit[] for a sentinel value. */
74 int limit[MAX_HUFCODE_BITS+1], base[MAX_HUFCODE_BITS], permute[MAX_SYMBOLS];
75 int minLen, maxLen;
76 };
77
78 /* Structure holding all the housekeeping data, including IO buffers and
79 * memory that persists between calls to bunzip
80 * Found the most used member:
81 * cat this_file.c | sed -e 's/"/ /g' -e "s/'/ /g" | xargs -n1 \
82 * | grep 'bd->' | sed 's/^.*bd->/bd->/' | sort | $PAGER
83 * and moved it (inbufBitCount) to offset 0.
84 */
85 struct bunzip_data {
86 /* I/O tracking data (file handles, buffers, positions, etc.) */
87 unsigned inbufBitCount, inbufBits;
88 int in_fd, out_fd, inbufCount, inbufPos /*, outbufPos*/;
89 uint8_t *inbuf /*,*outbuf*/;
90
91 /* State for interrupting output loop */
92 int writeCopies, writePos, writeRunCountdown, writeCount;
93 int writeCurrent; /* actually a uint8_t */
94
95 /* The CRC values stored in the block header and calculated from the data */
96 uint32_t headerCRC, totalCRC, writeCRC;
97
98 /* Intermediate buffer and its size (in bytes) */
99 uint32_t *dbuf;
100 unsigned dbufSize;
101
102 /* For I/O error handling */
103 jmp_buf *jmpbuf;
104
105 /* Big things go last (register-relative addressing can be larger for big offsets) */
106 uint32_t crc32Table[256];
107 uint8_t selectors[32768]; /* nSelectors=15 bits */
108 struct group_data groups[MAX_GROUPS]; /* Huffman coding tables */
109 };
110 typedef struct bunzip_data bunzip_data;
111
112
113 /* Return the next nnn bits of input. All reads from the compressed input
114 are done through this function. All reads are big endian */
get_bits(bunzip_data * bd,int bits_wanted)115 static unsigned get_bits(bunzip_data *bd, int bits_wanted)
116 {
117 unsigned bits = 0;
118 /* Cache bd->inbufBitCount in a CPU register (hopefully): */
119 int bit_count = bd->inbufBitCount;
120
121 /* If we need to get more data from the byte buffer, do so. (Loop getting
122 one byte at a time to enforce endianness and avoid unaligned access.) */
123 while (bit_count < bits_wanted) {
124
125 /* If we need to read more data from file into byte buffer, do so */
126 if (bd->inbufPos == bd->inbufCount) {
127 /* if "no input fd" case: in_fd == -1, read fails, we jump */
128 bd->inbufCount = read(bd->in_fd, bd->inbuf, IOBUF_SIZE);
129 if (bd->inbufCount <= 0)
130 longjmp(*bd->jmpbuf, RETVAL_UNEXPECTED_INPUT_EOF);
131 bd->inbufPos = 0;
132 }
133
134 /* Avoid 32-bit overflow (dump bit buffer to top of output) */
135 if (bit_count >= 24) {
136 bits = bd->inbufBits & ((1U << bit_count) - 1);
137 bits_wanted -= bit_count;
138 bits <<= bits_wanted;
139 bit_count = 0;
140 }
141
142 /* Grab next 8 bits of input from buffer. */
143 bd->inbufBits = (bd->inbufBits << 8) | bd->inbuf[bd->inbufPos++];
144 bit_count += 8;
145 }
146
147 /* Calculate result */
148 bit_count -= bits_wanted;
149 bd->inbufBitCount = bit_count;
150 bits |= (bd->inbufBits >> bit_count) & ((1 << bits_wanted) - 1);
151
152 return bits;
153 }
154 //#define get_bits(bd, n) (dbg("%d:get_bits()", __LINE__), get_bits(bd, n))
155
156 /* Unpacks the next block and sets up for the inverse Burrows-Wheeler step. */
get_next_block(bunzip_data * bd)157 static int get_next_block(bunzip_data *bd)
158 {
159 int groupCount, selector,
160 i, j, symCount, symTotal, nSelectors, byteCount[256];
161 uint8_t uc, symToByte[256], mtfSymbol[256], *selectors;
162 uint32_t *dbuf;
163 unsigned origPtr, t;
164 unsigned dbufCount, runPos;
165 unsigned runCnt = runCnt; /* for compiler */
166
167 dbuf = bd->dbuf;
168 selectors = bd->selectors;
169
170 /* In bbox, we are ok with aborting through setjmp which is set up in start_bunzip */
171 #if 0
172 /* Reset longjmp I/O error handling */
173 i = setjmp(bd->jmpbuf);
174 if (i) return i;
175 #endif
176
177 /* Read in header signature and CRC, then validate signature.
178 (last block signature means CRC is for whole file, return now) */
179 i = get_bits(bd, 24);
180 j = get_bits(bd, 24);
181 bd->headerCRC = get_bits(bd, 32);
182 if ((i == 0x177245) && (j == 0x385090))
183 return RETVAL_LAST_BLOCK;
184 if ((i != 0x314159) || (j != 0x265359))
185 return RETVAL_NOT_BZIP_DATA;
186
187 /* We can add support for blockRandomised if anybody complains. There was
188 some code for this in busybox 1.0.0-pre3, but nobody ever noticed that
189 it didn't actually work. */
190 if (get_bits(bd, 1))
191 return RETVAL_OBSOLETE_INPUT;
192 origPtr = get_bits(bd, 24);
193 if (origPtr > bd->dbufSize)
194 return RETVAL_DATA_ERROR;
195
196 /* mapping table: if some byte values are never used (encoding things
197 like ascii text), the compression code removes the gaps to have fewer
198 symbols to deal with, and writes a sparse bitfield indicating which
199 values were present. We make a translation table to convert the symbols
200 back to the corresponding bytes. */
201 symTotal = 0;
202 i = 0;
203 t = get_bits(bd, 16);
204 do {
205 if (t & (1 << 15)) {
206 unsigned inner_map = get_bits(bd, 16);
207 do {
208 if (inner_map & (1 << 15))
209 symToByte[symTotal++] = i;
210 inner_map <<= 1;
211 i++;
212 } while (i & 15);
213 i -= 16;
214 }
215 t <<= 1;
216 i += 16;
217 } while (i < 256);
218
219 /* How many different Huffman coding groups does this block use? */
220 groupCount = get_bits(bd, 3);
221 if (groupCount < 2 || groupCount > MAX_GROUPS)
222 return RETVAL_DATA_ERROR;
223
224 /* nSelectors: Every GROUP_SIZE many symbols we select a new Huffman coding
225 group. Read in the group selector list, which is stored as MTF encoded
226 bit runs. (MTF=Move To Front, as each value is used it's moved to the
227 start of the list.) */
228 for (i = 0; i < groupCount; i++)
229 mtfSymbol[i] = i;
230 nSelectors = get_bits(bd, 15);
231 if (!nSelectors)
232 return RETVAL_DATA_ERROR;
233 for (i = 0; i < nSelectors; i++) {
234 uint8_t tmp_byte;
235 /* Get next value */
236 int n = 0;
237 while (get_bits(bd, 1)) {
238 n++;
239 if (n >= groupCount)
240 return RETVAL_DATA_ERROR;
241 }
242 /* Decode MTF to get the next selector */
243 tmp_byte = mtfSymbol[n];
244 while (--n >= 0)
245 mtfSymbol[n + 1] = mtfSymbol[n];
246 //We catch it later, in the second loop where we use selectors[i].
247 //Maybe this is a better place, though?
248 // if (tmp_byte >= groupCount) {
249 // dbg("%d: selectors[%d]:%d groupCount:%d",
250 // __LINE__, i, tmp_byte, groupCount);
251 // return RETVAL_DATA_ERROR;
252 // }
253 mtfSymbol[0] = selectors[i] = tmp_byte;
254 }
255
256 /* Read the Huffman coding tables for each group, which code for symTotal
257 literal symbols, plus two run symbols (RUNA, RUNB) */
258 symCount = symTotal + 2;
259 for (j = 0; j < groupCount; j++) {
260 uint8_t length[MAX_SYMBOLS];
261 /* 8 bits is ALMOST enough for temp[], see below */
262 unsigned temp[MAX_HUFCODE_BITS+1];
263 struct group_data *hufGroup;
264 int *base, *limit;
265 int minLen, maxLen, pp, len_m1;
266
267 /* Read Huffman code lengths for each symbol. They're stored in
268 a way similar to mtf; record a starting value for the first symbol,
269 and an offset from the previous value for every symbol after that.
270 (Subtracting 1 before the loop and then adding it back at the end is
271 an optimization that makes the test inside the loop simpler: symbol
272 length 0 becomes negative, so an unsigned inequality catches it.) */
273 len_m1 = get_bits(bd, 5) - 1;
274 for (i = 0; i < symCount; i++) {
275 for (;;) {
276 int two_bits;
277 if ((unsigned)len_m1 > (MAX_HUFCODE_BITS-1))
278 return RETVAL_DATA_ERROR;
279
280 /* If first bit is 0, stop. Else second bit indicates whether
281 to increment or decrement the value. Optimization: grab 2
282 bits and unget the second if the first was 0. */
283 two_bits = get_bits(bd, 2);
284 if (two_bits < 2) {
285 bd->inbufBitCount++;
286 break;
287 }
288
289 /* Add one if second bit 1, else subtract 1. Avoids if/else */
290 len_m1 += (((two_bits+1) & 2) - 1);
291 }
292
293 /* Correct for the initial -1, to get the final symbol length */
294 length[i] = len_m1 + 1;
295 }
296
297 /* Find largest and smallest lengths in this group */
298 minLen = maxLen = length[0];
299 for (i = 1; i < symCount; i++) {
300 if (length[i] > maxLen)
301 maxLen = length[i];
302 else if (length[i] < minLen)
303 minLen = length[i];
304 }
305
306 /* Calculate permute[], base[], and limit[] tables from length[].
307 *
308 * permute[] is the lookup table for converting Huffman coded symbols
309 * into decoded symbols. base[] is the amount to subtract from the
310 * value of a Huffman symbol of a given length when using permute[].
311 *
312 * limit[] indicates the largest numerical value a symbol with a given
313 * number of bits can have. This is how the Huffman codes can vary in
314 * length: each code with a value>limit[length] needs another bit.
315 */
316 hufGroup = bd->groups + j;
317 hufGroup->minLen = minLen;
318 hufGroup->maxLen = maxLen;
319
320 /* Note that minLen can't be smaller than 1, so we adjust the base
321 and limit array pointers so we're not always wasting the first
322 entry. We do this again when using them (during symbol decoding). */
323 base = hufGroup->base - 1;
324 limit = hufGroup->limit - 1;
325
326 /* Calculate permute[]. Concurrently, initialize temp[] and limit[]. */
327 pp = 0;
328 for (i = minLen; i <= maxLen; i++) {
329 int k;
330 temp[i] = limit[i] = 0;
331 for (k = 0; k < symCount; k++)
332 if (length[k] == i)
333 hufGroup->permute[pp++] = k;
334 }
335
336 /* Count symbols coded for at each bit length */
337 /* NB: in pathological cases, temp[8] can end ip being 256.
338 * That's why uint8_t is too small for temp[]. */
339 for (i = 0; i < symCount; i++)
340 temp[length[i]]++;
341
342 /* Calculate limit[] (the largest symbol-coding value at each bit
343 * length, which is (previous limit<<1)+symbols at this level), and
344 * base[] (number of symbols to ignore at each bit length, which is
345 * limit minus the cumulative count of symbols coded for already). */
346 pp = t = 0;
347 for (i = minLen; i < maxLen;) {
348 unsigned temp_i = temp[i];
349
350 pp += temp_i;
351
352 /* We read the largest possible symbol size and then unget bits
353 after determining how many we need, and those extra bits could
354 be set to anything. (They're noise from future symbols.) At
355 each level we're really only interested in the first few bits,
356 so here we set all the trailing to-be-ignored bits to 1 so they
357 don't affect the value>limit[length] comparison. */
358 limit[i] = (pp << (maxLen - i)) - 1;
359 pp <<= 1;
360 t += temp_i;
361 base[++i] = pp - t;
362 }
363 limit[maxLen] = pp + temp[maxLen] - 1;
364 limit[maxLen+1] = INT_MAX; /* Sentinel value for reading next sym. */
365 base[minLen] = 0;
366 }
367
368 /* We've finished reading and digesting the block header. Now read this
369 block's Huffman coded symbols from the file and undo the Huffman coding
370 and run length encoding, saving the result into dbuf[dbufCount++] = uc */
371
372 /* Initialize symbol occurrence counters and symbol Move To Front table */
373 /*memset(byteCount, 0, sizeof(byteCount)); - smaller, but slower */
374 for (i = 0; i < 256; i++) {
375 byteCount[i] = 0;
376 mtfSymbol[i] = (uint8_t)i;
377 }
378
379 /* Loop through compressed symbols. */
380
381 runPos = dbufCount = selector = 0;
382 for (;;) {
383 struct group_data *hufGroup;
384 int *base, *limit;
385 int nextSym;
386 uint8_t ngrp;
387
388 /* Fetch next Huffman coding group from list. */
389 symCount = GROUP_SIZE - 1;
390 if (selector >= nSelectors)
391 return RETVAL_DATA_ERROR;
392 ngrp = selectors[selector++];
393 if (ngrp >= groupCount) {
394 dbg("%d selectors[%d]:%d groupCount:%d",
395 __LINE__, selector-1, ngrp, groupCount);
396 return RETVAL_DATA_ERROR;
397 }
398 hufGroup = bd->groups + ngrp;
399 base = hufGroup->base - 1;
400 limit = hufGroup->limit - 1;
401
402 continue_this_group:
403 /* Read next Huffman-coded symbol. */
404
405 /* Note: It is far cheaper to read maxLen bits and back up than it is
406 to read minLen bits and then add additional bit at a time, testing
407 as we go. Because there is a trailing last block (with file CRC),
408 there is no danger of the overread causing an unexpected EOF for a
409 valid compressed file.
410 */
411 if (1) {
412 /* As a further optimization, we do the read inline
413 (falling back to a call to get_bits if the buffer runs dry).
414 */
415 int new_cnt;
416 while ((new_cnt = bd->inbufBitCount - hufGroup->maxLen) < 0) {
417 /* bd->inbufBitCount < hufGroup->maxLen */
418 if (bd->inbufPos == bd->inbufCount) {
419 nextSym = get_bits(bd, hufGroup->maxLen);
420 goto got_huff_bits;
421 }
422 bd->inbufBits = (bd->inbufBits << 8) | bd->inbuf[bd->inbufPos++];
423 bd->inbufBitCount += 8;
424 };
425 bd->inbufBitCount = new_cnt; /* "bd->inbufBitCount -= hufGroup->maxLen;" */
426 nextSym = (bd->inbufBits >> new_cnt) & ((1 << hufGroup->maxLen) - 1);
427 got_huff_bits: ;
428 } else { /* unoptimized equivalent */
429 nextSym = get_bits(bd, hufGroup->maxLen);
430 }
431 /* Figure how many bits are in next symbol and unget extras */
432 i = hufGroup->minLen;
433 while (nextSym > limit[i])
434 ++i;
435 j = hufGroup->maxLen - i;
436 if (j < 0)
437 return RETVAL_DATA_ERROR;
438 bd->inbufBitCount += j;
439
440 /* Huffman decode value to get nextSym (with bounds checking) */
441 nextSym = (nextSym >> j) - base[i];
442 if ((unsigned)nextSym >= MAX_SYMBOLS)
443 return RETVAL_DATA_ERROR;
444 nextSym = hufGroup->permute[nextSym];
445
446 /* We have now decoded the symbol, which indicates either a new literal
447 byte, or a repeated run of the most recent literal byte. First,
448 check if nextSym indicates a repeated run, and if so loop collecting
449 how many times to repeat the last literal. */
450 if ((unsigned)nextSym <= SYMBOL_RUNB) { /* RUNA or RUNB */
451
452 /* If this is the start of a new run, zero out counter */
453 if (runPos == 0) {
454 runPos = 1;
455 runCnt = 0;
456 }
457
458 /* Neat trick that saves 1 symbol: instead of or-ing 0 or 1 at
459 each bit position, add 1 or 2 instead. For example,
460 1011 is 1<<0 + 1<<1 + 2<<2. 1010 is 2<<0 + 2<<1 + 1<<2.
461 You can make any bit pattern that way using 1 less symbol than
462 the basic or 0/1 method (except all bits 0, which would use no
463 symbols, but a run of length 0 doesn't mean anything in this
464 context). Thus space is saved. */
465 runCnt += (runPos << nextSym); /* +runPos if RUNA; +2*runPos if RUNB */
466 //The 32-bit overflow of runCnt wasn't yet seen, but probably can happen.
467 //This would be the fix (catches too large count way before it can overflow):
468 // if (runCnt > bd->dbufSize) {
469 // dbg("runCnt:%u > dbufSize:%u RETVAL_DATA_ERROR",
470 // runCnt, bd->dbufSize);
471 // return RETVAL_DATA_ERROR;
472 // }
473 if (runPos < bd->dbufSize) runPos <<= 1;
474 goto end_of_huffman_loop;
475 }
476
477 /* When we hit the first non-run symbol after a run, we now know
478 how many times to repeat the last literal, so append that many
479 copies to our buffer of decoded symbols (dbuf) now. (The last
480 literal used is the one at the head of the mtfSymbol array.) */
481 if (runPos != 0) {
482 uint8_t tmp_byte;
483 if (dbufCount + runCnt > bd->dbufSize) {
484 dbg("dbufCount:%u+runCnt:%u %u > dbufSize:%u RETVAL_DATA_ERROR",
485 dbufCount, runCnt, dbufCount + runCnt, bd->dbufSize);
486 return RETVAL_DATA_ERROR;
487 }
488 tmp_byte = symToByte[mtfSymbol[0]];
489 byteCount[tmp_byte] += runCnt;
490 while ((int)--runCnt >= 0)
491 dbuf[dbufCount++] = (uint32_t)tmp_byte;
492 runPos = 0;
493 }
494
495 /* Is this the terminating symbol? */
496 if (nextSym > symTotal) break;
497
498 /* At this point, nextSym indicates a new literal character. Subtract
499 one to get the position in the MTF array at which this literal is
500 currently to be found. (Note that the result can't be -1 or 0,
501 because 0 and 1 are RUNA and RUNB. But another instance of the
502 first symbol in the mtf array, position 0, would have been handled
503 as part of a run above. Therefore 1 unused mtf position minus
504 2 non-literal nextSym values equals -1.) */
505 if (dbufCount >= bd->dbufSize) return RETVAL_DATA_ERROR;
506 i = nextSym - 1;
507 uc = mtfSymbol[i];
508
509 /* Adjust the MTF array. Since we typically expect to move only a
510 * small number of symbols, and are bound by 256 in any case, using
511 * memmove here would typically be bigger and slower due to function
512 * call overhead and other assorted setup costs. */
513 do {
514 mtfSymbol[i] = mtfSymbol[i-1];
515 } while (--i);
516 mtfSymbol[0] = uc;
517 uc = symToByte[uc];
518
519 /* We have our literal byte. Save it into dbuf. */
520 byteCount[uc]++;
521 dbuf[dbufCount++] = (uint32_t)uc;
522
523 /* Skip group initialization if we're not done with this group. Done
524 * this way to avoid compiler warning. */
525 end_of_huffman_loop:
526 if (--symCount >= 0) goto continue_this_group;
527 }
528
529 /* At this point, we've read all the Huffman-coded symbols (and repeated
530 runs) for this block from the input stream, and decoded them into the
531 intermediate buffer. There are dbufCount many decoded bytes in dbuf[].
532 Now undo the Burrows-Wheeler transform on dbuf.
533 See http://dogma.net/markn/articles/bwt/bwt.htm
534 */
535
536 /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */
537 j = 0;
538 for (i = 0; i < 256; i++) {
539 int tmp_count = j + byteCount[i];
540 byteCount[i] = j;
541 j = tmp_count;
542 }
543
544 /* Figure out what order dbuf would be in if we sorted it. */
545 for (i = 0; i < dbufCount; i++) {
546 uint8_t tmp_byte = (uint8_t)dbuf[i];
547 int tmp_count = byteCount[tmp_byte];
548 dbuf[tmp_count] |= (i << 8);
549 byteCount[tmp_byte] = tmp_count + 1;
550 }
551
552 /* Decode first byte by hand to initialize "previous" byte. Note that it
553 doesn't get output, and if the first three characters are identical
554 it doesn't qualify as a run (hence writeRunCountdown=5). */
555 if (dbufCount) {
556 uint32_t tmp;
557 if ((int)origPtr >= dbufCount) return RETVAL_DATA_ERROR;
558 tmp = dbuf[origPtr];
559 bd->writeCurrent = (uint8_t)tmp;
560 bd->writePos = (tmp >> 8);
561 bd->writeRunCountdown = 5;
562 }
563 bd->writeCount = dbufCount;
564
565 return RETVAL_OK;
566 }
567
568 /* Undo Burrows-Wheeler transform on intermediate buffer to produce output.
569 If start_bunzip was initialized with out_fd=-1, then up to len bytes of
570 data are written to outbuf. Return value is number of bytes written or
571 error (all errors are negative numbers). If out_fd!=-1, outbuf and len
572 are ignored, data is written to out_fd and return is RETVAL_OK or error.
573
574 NB: read_bunzip returns < 0 on error, or the number of *unfilled* bytes
575 in outbuf. IOW: on EOF returns len ("all bytes are not filled"), not 0.
576 (Why? This allows to get rid of one local variable)
577 */
read_bunzip(bunzip_data * bd,char * outbuf,int len)578 static int read_bunzip(bunzip_data *bd, char *outbuf, int len)
579 {
580 const uint32_t *dbuf;
581 int pos, current, previous;
582 uint32_t CRC;
583
584 /* If we already have error/end indicator, return it */
585 if (bd->writeCount < 0)
586 return bd->writeCount;
587
588 dbuf = bd->dbuf;
589
590 /* Register-cached state (hopefully): */
591 pos = bd->writePos;
592 current = bd->writeCurrent;
593 CRC = bd->writeCRC; /* small loss on x86-32 (not enough regs), win on x86-64 */
594
595 /* We will always have pending decoded data to write into the output
596 buffer unless this is the very first call (in which case we haven't
597 Huffman-decoded a block into the intermediate buffer yet). */
598 if (bd->writeCopies) {
599
600 dec_writeCopies:
601 /* Inside the loop, writeCopies means extra copies (beyond 1) */
602 --bd->writeCopies;
603
604 /* Loop outputting bytes */
605 for (;;) {
606
607 /* If the output buffer is full, save cached state and return */
608 if (--len < 0) {
609 /* Unlikely branch.
610 * Use of "goto" instead of keeping code here
611 * helps compiler to realize this. */
612 goto outbuf_full;
613 }
614
615 /* Write next byte into output buffer, updating CRC */
616 *outbuf++ = current;
617 CRC = (CRC << 8) ^ bd->crc32Table[(CRC >> 24) ^ current];
618
619 /* Loop now if we're outputting multiple copies of this byte */
620 if (bd->writeCopies) {
621 /* Unlikely branch */
622 /*--bd->writeCopies;*/
623 /*continue;*/
624 /* Same, but (ab)using other existing --writeCopies operation
625 * (and this if() compiles into just test+branch pair): */
626 goto dec_writeCopies;
627 }
628 decode_next_byte:
629 if (--bd->writeCount < 0)
630 break; /* input block is fully consumed, need next one */
631
632 /* Follow sequence vector to undo Burrows-Wheeler transform */
633 previous = current;
634 pos = dbuf[pos];
635 current = (uint8_t)pos;
636 pos >>= 8;
637
638 /* After 3 consecutive copies of the same byte, the 4th
639 * is a repeat count. We count down from 4 instead
640 * of counting up because testing for non-zero is faster */
641 if (--bd->writeRunCountdown != 0) {
642 if (current != previous)
643 bd->writeRunCountdown = 4;
644 } else {
645 /* Unlikely branch */
646 /* We have a repeated run, this byte indicates the count */
647 bd->writeCopies = current;
648 current = previous;
649 bd->writeRunCountdown = 5;
650
651 /* Sometimes there are just 3 bytes (run length 0) */
652 if (!bd->writeCopies) goto decode_next_byte;
653
654 /* Subtract the 1 copy we'd output anyway to get extras */
655 --bd->writeCopies;
656 }
657 } /* for(;;) */
658
659 /* Decompression of this input block completed successfully */
660 bd->writeCRC = CRC = ~CRC;
661 bd->totalCRC = ((bd->totalCRC << 1) | (bd->totalCRC >> 31)) ^ CRC;
662
663 /* If this block had a CRC error, force file level CRC error */
664 if (CRC != bd->headerCRC) {
665 bd->totalCRC = bd->headerCRC + 1;
666 return RETVAL_LAST_BLOCK;
667 }
668 }
669
670 /* Refill the intermediate buffer by Huffman-decoding next block of input */
671 {
672 int r = get_next_block(bd);
673 if (r) { /* error/end */
674 bd->writeCount = r;
675 return (r != RETVAL_LAST_BLOCK) ? r : len;
676 }
677 }
678
679 CRC = ~0;
680 pos = bd->writePos;
681 current = bd->writeCurrent;
682 goto decode_next_byte;
683
684 outbuf_full:
685 /* Output buffer is full, save cached state and return */
686 bd->writePos = pos;
687 bd->writeCurrent = current;
688 bd->writeCRC = CRC;
689
690 bd->writeCopies++;
691
692 return 0;
693 }
694
695 /* Allocate the structure, read file header. If in_fd==-1, inbuf must contain
696 a complete bunzip file (len bytes long). If in_fd!=-1, inbuf and len are
697 ignored, and data is read from file handle into temporary buffer. */
698
699 /* Because bunzip2 is used for help text unpacking, and because bb_show_usage()
700 should work for NOFORK applets too, we must be extremely careful to not leak
701 any allocations! */
start_bunzip(void * jmpbuf,bunzip_data ** bdp,int in_fd,const void * inbuf,int len)702 static int FAST_FUNC start_bunzip(
703 void *jmpbuf,
704 bunzip_data **bdp,
705 int in_fd,
706 const void *inbuf, int len)
707 {
708 bunzip_data *bd;
709 unsigned i;
710 enum {
711 BZh0 = ('B' << 24) + ('Z' << 16) + ('h' << 8) + '0',
712 h0 = ('h' << 8) + '0',
713 };
714
715 /* Figure out how much data to allocate */
716 i = sizeof(bunzip_data);
717 if (in_fd != -1)
718 i += IOBUF_SIZE;
719
720 /* Allocate bunzip_data. Most fields initialize to zero. */
721 bd = *bdp = xzalloc(i);
722
723 bd->jmpbuf = jmpbuf;
724
725 /* Setup input buffer */
726 bd->in_fd = in_fd;
727 if (-1 == in_fd) {
728 /* in this case, bd->inbuf is read-only */
729 bd->inbuf = (void*)inbuf; /* cast away const-ness */
730 } else {
731 bd->inbuf = (uint8_t*)(bd + 1);
732 memcpy(bd->inbuf, inbuf, len);
733 }
734 bd->inbufCount = len;
735
736 /* Init the CRC32 table (big endian) */
737 crc32_filltable(bd->crc32Table, 1);
738
739 /* Ensure that file starts with "BZh['1'-'9']." */
740 /* Update: now caller verifies 1st two bytes, makes .gz/.bz2
741 * integration easier */
742 /* was: */
743 /* i = get_bits(bd, 32); */
744 /* if ((unsigned)(i - BZh0 - 1) >= 9) return RETVAL_NOT_BZIP_DATA; */
745 i = get_bits(bd, 16);
746 if ((unsigned)(i - h0 - 1) >= 9) return RETVAL_NOT_BZIP_DATA;
747
748 /* Fourth byte (ascii '1'-'9') indicates block size in units of 100k of
749 uncompressed data. Allocate intermediate buffer for block. */
750 /* bd->dbufSize = 100000 * (i - BZh0); */
751 bd->dbufSize = 100000 * (i - h0);
752
753 /* Cannot use xmalloc - may leak bd in NOFORK case! */
754 bd->dbuf = malloc_or_warn(bd->dbufSize * sizeof(bd->dbuf[0]));
755 if (!bd->dbuf) {
756 free(bd);
757 xfunc_die();
758 }
759 return RETVAL_OK;
760 }
761
dealloc_bunzip(bunzip_data * bd)762 static void FAST_FUNC dealloc_bunzip(bunzip_data *bd)
763 {
764 free(bd->dbuf);
765 free(bd);
766 }
767
768
769 /* Decompress src_fd to dst_fd. Stops at end of bzip data, not end of file. */
IF_DESKTOP(long long)770 IF_DESKTOP(long long) int FAST_FUNC
771 unpack_bz2_stream(transformer_state_t *xstate)
772 {
773 IF_DESKTOP(long long total_written = 0;)
774 bunzip_data *bd;
775 char *outbuf;
776 int i;
777 unsigned len;
778
779 if (check_signature16(xstate, BZIP2_MAGIC))
780 return -1;
781
782 outbuf = xmalloc(IOBUF_SIZE);
783 len = 0;
784 while (1) { /* "Process one BZ... stream" loop */
785 jmp_buf jmpbuf;
786
787 /* Setup for I/O error handling via longjmp */
788 i = setjmp(jmpbuf);
789 if (i == 0)
790 i = start_bunzip(&jmpbuf, &bd, xstate->src_fd, outbuf + 2, len);
791
792 if (i == 0) {
793 while (1) { /* "Produce some output bytes" loop */
794 i = read_bunzip(bd, outbuf, IOBUF_SIZE);
795 if (i < 0) /* error? */
796 break;
797 i = IOBUF_SIZE - i; /* number of bytes produced */
798 if (i == 0) /* EOF? */
799 break;
800 if (i != transformer_write(xstate, outbuf, i)) {
801 i = RETVAL_SHORT_WRITE;
802 goto release_mem;
803 }
804 IF_DESKTOP(total_written += i;)
805 }
806 }
807
808 if (i != RETVAL_LAST_BLOCK
809 /* Observed case when i == RETVAL_OK:
810 * "bzcat z.bz2", where "z.bz2" is a bzipped zero-length file
811 * (to be exact, z.bz2 is exactly these 14 bytes:
812 * 42 5a 68 39 17 72 45 38 50 90 00 00 00 00).
813 */
814 && i != RETVAL_OK
815 ) {
816 bb_error_msg("bunzip error %d", i);
817 break;
818 }
819 if (bd->headerCRC != bd->totalCRC) {
820 bb_simple_error_msg("CRC error");
821 break;
822 }
823
824 /* Successfully unpacked one BZ stream */
825 i = RETVAL_OK;
826
827 /* Do we have "BZ..." after last processed byte?
828 * pbzip2 (parallelized bzip2) produces such files.
829 */
830 len = bd->inbufCount - bd->inbufPos;
831 memcpy(outbuf, &bd->inbuf[bd->inbufPos], len);
832 if (len < 2) {
833 if (safe_read(xstate->src_fd, outbuf + len, 2 - len) != 2 - len)
834 break;
835 len = 2;
836 }
837 if (*(uint16_t*)outbuf != BZIP2_MAGIC) /* "BZ"? */
838 break;
839 dealloc_bunzip(bd);
840 len -= 2;
841 }
842
843 release_mem:
844 dealloc_bunzip(bd);
845 free(outbuf);
846
847 return i ? i : IF_DESKTOP(total_written) + 0;
848 }
849
850 char* FAST_FUNC
unpack_bz2_data(const char * packed,int packed_len,int unpacked_len)851 unpack_bz2_data(const char *packed, int packed_len, int unpacked_len)
852 {
853 char *outbuf = NULL;
854 bunzip_data *bd;
855 int i;
856 jmp_buf jmpbuf;
857
858 /* Setup for I/O error handling via longjmp */
859 i = setjmp(jmpbuf);
860 if (i == 0) {
861 i = start_bunzip(&jmpbuf,
862 &bd,
863 /* src_fd: */ -1,
864 /* inbuf: */ packed,
865 /* len: */ packed_len
866 );
867 }
868 /* read_bunzip can longjmp and end up here with i != 0
869 * on read data errors! Not trivial */
870 if (i == 0) {
871 /* Cannot use xmalloc: will leak bd in NOFORK case! */
872 outbuf = malloc_or_warn(unpacked_len);
873 if (outbuf)
874 read_bunzip(bd, outbuf, unpacked_len);
875 }
876 dealloc_bunzip(bd);
877 return outbuf;
878 }
879
880 #ifdef TESTING
881
882 static char *const bunzip_errors[] = {
883 NULL, "Bad file checksum", "Not bzip data",
884 "Unexpected input EOF", "Unexpected output EOF", "Data error",
885 "Out of memory", "Obsolete (pre 0.9.5) bzip format not supported"
886 };
887
888 /* Dumb little test thing, decompress stdin to stdout */
main(int argc,char ** argv)889 int main(int argc, char **argv)
890 {
891 char c;
892
893 int i = unpack_bz2_stream(0, 1);
894 if (i < 0)
895 fprintf(stderr, "%s\n", bunzip_errors[-i]);
896 else if (read(STDIN_FILENO, &c, 1))
897 fprintf(stderr, "Trailing garbage ignored\n");
898 return -i;
899 }
900 #endif
901