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 Licensed under GPLv2 or later, see file LICENSE in this tarball for details. 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 (www.hospiceacadiana.com) in the name of 26 the woman I loved, Toni W. Hagan, who passed away Feb. 12, 2003. 27 28 Manuel 29 */ 30 31#include "libbb.h" 32#include "unarchive.h" 33 34/* Constants for Huffman coding */ 35#define MAX_GROUPS 6 36#define GROUP_SIZE 50 /* 64 would have been more efficient */ 37#define MAX_HUFCODE_BITS 20 /* Longest Huffman code allowed */ 38#define MAX_SYMBOLS 258 /* 256 literals + RUNA + RUNB */ 39#define SYMBOL_RUNA 0 40#define SYMBOL_RUNB 1 41 42/* Status return values */ 43#define RETVAL_OK 0 44#define RETVAL_LAST_BLOCK (-1) 45#define RETVAL_NOT_BZIP_DATA (-2) 46#define RETVAL_UNEXPECTED_INPUT_EOF (-3) 47#define RETVAL_UNEXPECTED_OUTPUT_EOF (-4) 48#define RETVAL_DATA_ERROR (-5) 49#define RETVAL_OUT_OF_MEMORY (-6) 50#define RETVAL_OBSOLETE_INPUT (-7) 51 52/* Other housekeeping constants */ 53#define IOBUF_SIZE 4096 54 55/* This is what we know about each Huffman coding group */ 56struct group_data { 57 /* We have an extra slot at the end of limit[] for a sentinal value. */ 58 int limit[MAX_HUFCODE_BITS+1], base[MAX_HUFCODE_BITS], permute[MAX_SYMBOLS]; 59 int minLen, maxLen; 60}; 61 62/* Structure holding all the housekeeping data, including IO buffers and 63 memory that persists between calls to bunzip */ 64 65struct bunzip_data { 66 /* State for interrupting output loop */ 67 int writeCopies, writePos, writeRunCountdown, writeCount, writeCurrent; 68 69 /* I/O tracking data (file handles, buffers, positions, etc.) */ 70 int in_fd, out_fd, inbufCount, inbufPos /*, outbufPos*/; 71 unsigned char *inbuf /*,*outbuf*/; 72 unsigned inbufBitCount, inbufBits; 73 74 /* The CRC values stored in the block header and calculated from the data */ 75 uint32_t headerCRC, totalCRC, writeCRC; 76 77 /* Intermediate buffer and its size (in bytes) */ 78 unsigned *dbuf, dbufSize; 79 80 /* For I/O error handling */ 81 jmp_buf jmpbuf; 82 83 /* Big things go last (register-relative addressing can be larger for big offsets */ 84 uint32_t crc32Table[256]; 85 unsigned char selectors[32768]; /* nSelectors=15 bits */ 86 struct group_data groups[MAX_GROUPS]; /* Huffman coding tables */ 87}; 88/* typedef struct bunzip_data bunzip_data; -- done in .h file */ 89 90 91/* Return the next nnn bits of input. All reads from the compressed input 92 are done through this function. All reads are big endian */ 93 94static unsigned get_bits(bunzip_data *bd, char bits_wanted) 95{ 96 unsigned bits = 0; 97 98 /* If we need to get more data from the byte buffer, do so. (Loop getting 99 one byte at a time to enforce endianness and avoid unaligned access.) */ 100 101 while (bd->inbufBitCount < bits_wanted) { 102 103 /* If we need to read more data from file into byte buffer, do so */ 104 105 if (bd->inbufPos == bd->inbufCount) { 106 /* if "no input fd" case: in_fd == -1, read fails, we jump */ 107 bd->inbufCount = read(bd->in_fd, bd->inbuf, IOBUF_SIZE); 108 if (bd->inbufCount <= 0) 109 longjmp(bd->jmpbuf, RETVAL_UNEXPECTED_INPUT_EOF); 110 bd->inbufPos = 0; 111 } 112 113 /* Avoid 32-bit overflow (dump bit buffer to top of output) */ 114 115 if (bd->inbufBitCount >= 24) { 116 bits = bd->inbufBits & ((1 << bd->inbufBitCount) - 1); 117 bits_wanted -= bd->inbufBitCount; 118 bits <<= bits_wanted; 119 bd->inbufBitCount = 0; 120 } 121 122 /* Grab next 8 bits of input from buffer. */ 123 124 bd->inbufBits = (bd->inbufBits<<8) | bd->inbuf[bd->inbufPos++]; 125 bd->inbufBitCount += 8; 126 } 127 128 /* Calculate result */ 129 130 bd->inbufBitCount -= bits_wanted; 131 bits |= (bd->inbufBits >> bd->inbufBitCount) & ((1 << bits_wanted) - 1); 132 133 return bits; 134} 135 136/* Unpacks the next block and sets up for the inverse burrows-wheeler step. */ 137 138static int get_next_block(bunzip_data *bd) 139{ 140 struct group_data *hufGroup; 141 int dbufCount, nextSym, dbufSize, groupCount, *base, *limit, selector, 142 i, j, k, t, runPos, symCount, symTotal, nSelectors, byteCount[256]; 143 unsigned char uc, symToByte[256], mtfSymbol[256], *selectors; 144 unsigned *dbuf, origPtr; 145 146 dbuf = bd->dbuf; 147 dbufSize = bd->dbufSize; 148 selectors = bd->selectors; 149 150 /* Reset longjmp I/O error handling */ 151 152 i = setjmp(bd->jmpbuf); 153 if (i) return i; 154 155 /* Read in header signature and CRC, then validate signature. 156 (last block signature means CRC is for whole file, return now) */ 157 158 i = get_bits(bd, 24); 159 j = get_bits(bd, 24); 160 bd->headerCRC = get_bits(bd, 32); 161 if ((i == 0x177245) && (j == 0x385090)) return RETVAL_LAST_BLOCK; 162 if ((i != 0x314159) || (j != 0x265359)) return RETVAL_NOT_BZIP_DATA; 163 164 /* We can add support for blockRandomised if anybody complains. There was 165 some code for this in busybox 1.0.0-pre3, but nobody ever noticed that 166 it didn't actually work. */ 167 168 if (get_bits(bd, 1)) return RETVAL_OBSOLETE_INPUT; 169 origPtr = get_bits(bd, 24); 170 if (origPtr > dbufSize) return RETVAL_DATA_ERROR; 171 172 /* mapping table: if some byte values are never used (encoding things 173 like ascii text), the compression code removes the gaps to have fewer 174 symbols to deal with, and writes a sparse bitfield indicating which 175 values were present. We make a translation table to convert the symbols 176 back to the corresponding bytes. */ 177 178 t = get_bits(bd, 16); 179 symTotal = 0; 180 for (i = 0; i < 16; i++) { 181 if (t & (1 << (15-i))) { 182 k = get_bits(bd, 16); 183 for (j = 0; j < 16; j++) 184 if (k & (1 << (15-j))) 185 symToByte[symTotal++] = (16*i) + j; 186 } 187 } 188 189 /* How many different Huffman coding groups does this block use? */ 190 191 groupCount = get_bits(bd, 3); 192 if (groupCount < 2 || groupCount > MAX_GROUPS) 193 return RETVAL_DATA_ERROR; 194 195 /* nSelectors: Every GROUP_SIZE many symbols we select a new Huffman coding 196 group. Read in the group selector list, which is stored as MTF encoded 197 bit runs. (MTF=Move To Front, as each value is used it's moved to the 198 start of the list.) */ 199 200 nSelectors = get_bits(bd, 15); 201 if (!nSelectors) return RETVAL_DATA_ERROR; 202 for (i = 0; i < groupCount; i++) mtfSymbol[i] = i; 203 for (i = 0; i < nSelectors; i++) { 204 205 /* Get next value */ 206 207 for (j = 0; get_bits(bd, 1); j++) 208 if (j>=groupCount) return RETVAL_DATA_ERROR; 209 210 /* Decode MTF to get the next selector */ 211 212 uc = mtfSymbol[j]; 213 for (;j;j--) mtfSymbol[j] = mtfSymbol[j-1]; 214 mtfSymbol[0] = selectors[i] = uc; 215 } 216 217 /* Read the Huffman coding tables for each group, which code for symTotal 218 literal symbols, plus two run symbols (RUNA, RUNB) */ 219 220 symCount = symTotal + 2; 221 for (j = 0; j < groupCount; j++) { 222 unsigned char length[MAX_SYMBOLS], temp[MAX_HUFCODE_BITS+1]; 223 int minLen, maxLen, pp; 224 225 /* Read Huffman code lengths for each symbol. They're stored in 226 a way similar to mtf; record a starting value for the first symbol, 227 and an offset from the previous value for everys symbol after that. 228 (Subtracting 1 before the loop and then adding it back at the end is 229 an optimization that makes the test inside the loop simpler: symbol 230 length 0 becomes negative, so an unsigned inequality catches it.) */ 231 232 t = get_bits(bd, 5) - 1; 233 for (i = 0; i < symCount; i++) { 234 for (;;) { 235 if ((unsigned)t > (MAX_HUFCODE_BITS-1)) 236 return RETVAL_DATA_ERROR; 237 238 /* If first bit is 0, stop. Else second bit indicates whether 239 to increment or decrement the value. Optimization: grab 2 240 bits and unget the second if the first was 0. */ 241 242 k = get_bits(bd, 2); 243 if (k < 2) { 244 bd->inbufBitCount++; 245 break; 246 } 247 248 /* Add one if second bit 1, else subtract 1. Avoids if/else */ 249 250 t += (((k+1) & 2) - 1); 251 } 252 253 /* Correct for the initial -1, to get the final symbol length */ 254 255 length[i] = t + 1; 256 } 257 258 /* Find largest and smallest lengths in this group */ 259 260 minLen = maxLen = length[0]; 261 for (i = 1; i < symCount; i++) { 262 if (length[i] > maxLen) maxLen = length[i]; 263 else if (length[i] < minLen) minLen = length[i]; 264 } 265 266 /* Calculate permute[], base[], and limit[] tables from length[]. 267 * 268 * permute[] is the lookup table for converting Huffman coded symbols 269 * into decoded symbols. base[] is the amount to subtract from the 270 * value of a Huffman symbol of a given length when using permute[]. 271 * 272 * limit[] indicates the largest numerical value a symbol with a given 273 * number of bits can have. This is how the Huffman codes can vary in 274 * length: each code with a value>limit[length] needs another bit. 275 */ 276 277 hufGroup = bd->groups + j; 278 hufGroup->minLen = minLen; 279 hufGroup->maxLen = maxLen; 280 281 /* Note that minLen can't be smaller than 1, so we adjust the base 282 and limit array pointers so we're not always wasting the first 283 entry. We do this again when using them (during symbol decoding).*/ 284 285 base = hufGroup->base - 1; 286 limit = hufGroup->limit - 1; 287 288 /* Calculate permute[]. Concurently, initialize temp[] and limit[]. */ 289 290 pp = 0; 291 for (i = minLen; i <= maxLen; i++) { 292 temp[i] = limit[i] = 0; 293 for (t = 0; t < symCount; t++) 294 if (length[t] == i) 295 hufGroup->permute[pp++] = t; 296 } 297 298 /* Count symbols coded for at each bit length */ 299 300 for (i = 0; i < symCount; i++) temp[length[i]]++; 301 302 /* Calculate limit[] (the largest symbol-coding value at each bit 303 * length, which is (previous limit<<1)+symbols at this level), and 304 * base[] (number of symbols to ignore at each bit length, which is 305 * limit minus the cumulative count of symbols coded for already). */ 306 307 pp = t = 0; 308 for (i = minLen; i < maxLen; i++) { 309 pp += temp[i]; 310 311 /* We read the largest possible symbol size and then unget bits 312 after determining how many we need, and those extra bits could 313 be set to anything. (They're noise from future symbols.) At 314 each level we're really only interested in the first few bits, 315 so here we set all the trailing to-be-ignored bits to 1 so they 316 don't affect the value>limit[length] comparison. */ 317 318 limit[i] = (pp << (maxLen - i)) - 1; 319 pp <<= 1; 320 t += temp[i]; 321 base[i+1] = pp - t; 322 } 323 limit[maxLen+1] = INT_MAX; /* Sentinal value for reading next sym. */ 324 limit[maxLen] = pp + temp[maxLen] - 1; 325 base[minLen] = 0; 326 } 327 328 /* We've finished reading and digesting the block header. Now read this 329 block's Huffman coded symbols from the file and undo the Huffman coding 330 and run length encoding, saving the result into dbuf[dbufCount++]=uc */ 331 332 /* Initialize symbol occurrence counters and symbol Move To Front table */ 333 334 for (i = 0; i < 256; i++) { 335 byteCount[i] = 0; 336 mtfSymbol[i] = (unsigned char)i; 337 } 338 339 /* Loop through compressed symbols. */ 340 341 runPos = dbufCount = selector = 0; 342 for (;;) { 343 344 /* fetch next Huffman coding group from list. */ 345 346 symCount = GROUP_SIZE - 1; 347 if (selector >= nSelectors) return RETVAL_DATA_ERROR; 348 hufGroup = bd->groups + selectors[selector++]; 349 base = hufGroup->base - 1; 350 limit = hufGroup->limit - 1; 351 continue_this_group: 352 353 /* Read next Huffman-coded symbol. */ 354 355 /* Note: It is far cheaper to read maxLen bits and back up than it is 356 to read minLen bits and then an additional bit at a time, testing 357 as we go. Because there is a trailing last block (with file CRC), 358 there is no danger of the overread causing an unexpected EOF for a 359 valid compressed file. As a further optimization, we do the read 360 inline (falling back to a call to get_bits if the buffer runs 361 dry). The following (up to got_huff_bits:) is equivalent to 362 j = get_bits(bd, hufGroup->maxLen); 363 */ 364 365 while (bd->inbufBitCount < hufGroup->maxLen) { 366 if (bd->inbufPos == bd->inbufCount) { 367 j = get_bits(bd, hufGroup->maxLen); 368 goto got_huff_bits; 369 } 370 bd->inbufBits = (bd->inbufBits << 8) | bd->inbuf[bd->inbufPos++]; 371 bd->inbufBitCount += 8; 372 }; 373 bd->inbufBitCount -= hufGroup->maxLen; 374 j = (bd->inbufBits >> bd->inbufBitCount) & ((1 << hufGroup->maxLen) - 1); 375 376 got_huff_bits: 377 378 /* Figure how how many bits are in next symbol and unget extras */ 379 380 i = hufGroup->minLen; 381 while (j > limit[i]) ++i; 382 bd->inbufBitCount += (hufGroup->maxLen - i); 383 384 /* Huffman decode value to get nextSym (with bounds checking) */ 385 386 if (i > hufGroup->maxLen) 387 return RETVAL_DATA_ERROR; 388 j = (j >> (hufGroup->maxLen - i)) - base[i]; 389 if ((unsigned)j >= MAX_SYMBOLS) 390 return RETVAL_DATA_ERROR; 391 nextSym = hufGroup->permute[j]; 392 393 /* We have now decoded the symbol, which indicates either a new literal 394 byte, or a repeated run of the most recent literal byte. First, 395 check if nextSym indicates a repeated run, and if so loop collecting 396 how many times to repeat the last literal. */ 397 398 if ((unsigned)nextSym <= SYMBOL_RUNB) { /* RUNA or RUNB */ 399 400 /* If this is the start of a new run, zero out counter */ 401 402 if (!runPos) { 403 runPos = 1; 404 t = 0; 405 } 406 407 /* Neat trick that saves 1 symbol: instead of or-ing 0 or 1 at 408 each bit position, add 1 or 2 instead. For example, 409 1011 is 1<<0 + 1<<1 + 2<<2. 1010 is 2<<0 + 2<<1 + 1<<2. 410 You can make any bit pattern that way using 1 less symbol than 411 the basic or 0/1 method (except all bits 0, which would use no 412 symbols, but a run of length 0 doesn't mean anything in this 413 context). Thus space is saved. */ 414 415 t += (runPos << nextSym); /* +runPos if RUNA; +2*runPos if RUNB */ 416 if (runPos < dbufSize) runPos <<= 1; 417 goto end_of_huffman_loop; 418 } 419 420 /* When we hit the first non-run symbol after a run, we now know 421 how many times to repeat the last literal, so append that many 422 copies to our buffer of decoded symbols (dbuf) now. (The last 423 literal used is the one at the head of the mtfSymbol array.) */ 424 425 if (runPos) { 426 runPos = 0; 427 if (dbufCount + t >= dbufSize) return RETVAL_DATA_ERROR; 428 429 uc = symToByte[mtfSymbol[0]]; 430 byteCount[uc] += t; 431 while (t--) dbuf[dbufCount++] = uc; 432 } 433 434 /* Is this the terminating symbol? */ 435 436 if (nextSym > symTotal) break; 437 438 /* At this point, nextSym indicates a new literal character. Subtract 439 one to get the position in the MTF array at which this literal is 440 currently to be found. (Note that the result can't be -1 or 0, 441 because 0 and 1 are RUNA and RUNB. But another instance of the 442 first symbol in the mtf array, position 0, would have been handled 443 as part of a run above. Therefore 1 unused mtf position minus 444 2 non-literal nextSym values equals -1.) */ 445 446 if (dbufCount >= dbufSize) return RETVAL_DATA_ERROR; 447 i = nextSym - 1; 448 uc = mtfSymbol[i]; 449 450 /* Adjust the MTF array. Since we typically expect to move only a 451 * small number of symbols, and are bound by 256 in any case, using 452 * memmove here would typically be bigger and slower due to function 453 * call overhead and other assorted setup costs. */ 454 455 do { 456 mtfSymbol[i] = mtfSymbol[i-1]; 457 } while (--i); 458 mtfSymbol[0] = uc; 459 uc = symToByte[uc]; 460 461 /* We have our literal byte. Save it into dbuf. */ 462 463 byteCount[uc]++; 464 dbuf[dbufCount++] = (unsigned)uc; 465 466 /* Skip group initialization if we're not done with this group. Done 467 * this way to avoid compiler warning. */ 468 469 end_of_huffman_loop: 470 if (symCount--) goto continue_this_group; 471 } 472 473 /* At this point, we've read all the Huffman-coded symbols (and repeated 474 runs) for this block from the input stream, and decoded them into the 475 intermediate buffer. There are dbufCount many decoded bytes in dbuf[]. 476 Now undo the Burrows-Wheeler transform on dbuf. 477 See http://dogma.net/markn/articles/bwt/bwt.htm 478 */ 479 480 /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */ 481 482 j = 0; 483 for (i = 0; i < 256; i++) { 484 k = j + byteCount[i]; 485 byteCount[i] = j; 486 j = k; 487 } 488 489 /* Figure out what order dbuf would be in if we sorted it. */ 490 491 for (i = 0; i < dbufCount; i++) { 492 uc = (unsigned char)(dbuf[i] & 0xff); 493 dbuf[byteCount[uc]] |= (i << 8); 494 byteCount[uc]++; 495 } 496 497 /* Decode first byte by hand to initialize "previous" byte. Note that it 498 doesn't get output, and if the first three characters are identical 499 it doesn't qualify as a run (hence writeRunCountdown=5). */ 500 501 if (dbufCount) { 502 if (origPtr >= dbufCount) return RETVAL_DATA_ERROR; 503 bd->writePos = dbuf[origPtr]; 504 bd->writeCurrent = (unsigned char)(bd->writePos & 0xff); 505 bd->writePos >>= 8; 506 bd->writeRunCountdown = 5; 507 } 508 bd->writeCount = dbufCount; 509 510 return RETVAL_OK; 511} 512 513/* Undo burrows-wheeler transform on intermediate buffer to produce output. 514 If start_bunzip was initialized with out_fd=-1, then up to len bytes of 515 data are written to outbuf. Return value is number of bytes written or 516 error (all errors are negative numbers). If out_fd!=-1, outbuf and len 517 are ignored, data is written to out_fd and return is RETVAL_OK or error. 518*/ 519 520int read_bunzip(bunzip_data *bd, char *outbuf, int len) 521{ 522 const unsigned *dbuf; 523 int pos, current, previous, gotcount; 524 525 /* If last read was short due to end of file, return last block now */ 526 if (bd->writeCount < 0) return bd->writeCount; 527 528 gotcount = 0; 529 dbuf = bd->dbuf; 530 pos = bd->writePos; 531 current = bd->writeCurrent; 532 533 /* We will always have pending decoded data to write into the output 534 buffer unless this is the very first call (in which case we haven't 535 Huffman-decoded a block into the intermediate buffer yet). */ 536 537 if (bd->writeCopies) { 538 539 /* Inside the loop, writeCopies means extra copies (beyond 1) */ 540 541 --bd->writeCopies; 542 543 /* Loop outputting bytes */ 544 545 for (;;) { 546 547 /* If the output buffer is full, snapshot state and return */ 548 549 if (gotcount >= len) { 550 bd->writePos =pos; 551 bd->writeCurrent = current; 552 bd->writeCopies++; 553 return len; 554 } 555 556 /* Write next byte into output buffer, updating CRC */ 557 558 outbuf[gotcount++] = current; 559 bd->writeCRC = (bd->writeCRC << 8) 560 ^ bd->crc32Table[(bd->writeCRC >> 24) ^ current]; 561 562 /* Loop now if we're outputting multiple copies of this byte */ 563 564 if (bd->writeCopies) { 565 --bd->writeCopies; 566 continue; 567 } 568 decode_next_byte: 569 if (!bd->writeCount--) break; 570 /* Follow sequence vector to undo Burrows-Wheeler transform */ 571 previous = current; 572 pos = dbuf[pos]; 573 current = pos & 0xff; 574 pos >>= 8; 575 576 /* After 3 consecutive copies of the same byte, the 4th is a repeat 577 count. We count down from 4 instead 578 * of counting up because testing for non-zero is faster */ 579 580 if (--bd->writeRunCountdown) { 581 if (current != previous) 582 bd->writeRunCountdown = 4; 583 } else { 584 585 /* We have a repeated run, this byte indicates the count */ 586 587 bd->writeCopies = current; 588 current = previous; 589 bd->writeRunCountdown = 5; 590 591 /* Sometimes there are just 3 bytes (run length 0) */ 592 593 if (!bd->writeCopies) goto decode_next_byte; 594 595 /* Subtract the 1 copy we'd output anyway to get extras */ 596 597 --bd->writeCopies; 598 } 599 } 600 601 /* Decompression of this block completed successfully */ 602 603 bd->writeCRC = ~bd->writeCRC; 604 bd->totalCRC = ((bd->totalCRC << 1) | (bd->totalCRC >> 31)) ^ bd->writeCRC; 605 606 /* If this block had a CRC error, force file level CRC error. */ 607 608 if (bd->writeCRC != bd->headerCRC) { 609 bd->totalCRC = bd->headerCRC+1; 610 return RETVAL_LAST_BLOCK; 611 } 612 } 613 614 /* Refill the intermediate buffer by Huffman-decoding next block of input */ 615 /* (previous is just a convenient unused temp variable here) */ 616 617 previous = get_next_block(bd); 618 if (previous) { 619 bd->writeCount = previous; 620 return (previous != RETVAL_LAST_BLOCK) ? previous : gotcount; 621 } 622 bd->writeCRC = ~0; 623 pos = bd->writePos; 624 current = bd->writeCurrent; 625 goto decode_next_byte; 626} 627 628 629/* Allocate the structure, read file header. If in_fd==-1, inbuf must contain 630 a complete bunzip file (len bytes long). If in_fd!=-1, inbuf and len are 631 ignored, and data is read from file handle into temporary buffer. */ 632 633/* Because bunzip2 is used for help text unpacking, and because bb_show_usage() 634 should work for NOFORK applets too, we must be extremely careful to not leak 635 any allocations! */ 636 637int start_bunzip(bunzip_data **bdp, int in_fd, const unsigned char *inbuf, 638 int len) 639{ 640 bunzip_data *bd; 641 unsigned i; 642 enum { 643 BZh0 = ('B' << 24) + ('Z' << 16) + ('h' << 8) + '0' 644 }; 645 646 /* Figure out how much data to allocate */ 647 648 i = sizeof(bunzip_data); 649 if (in_fd != -1) i += IOBUF_SIZE; 650 651 /* Allocate bunzip_data. Most fields initialize to zero. */ 652 653 bd = *bdp = xzalloc(i); 654 655 /* Setup input buffer */ 656 657 bd->in_fd = in_fd; 658 if (-1 == in_fd) { 659 /* in this case, bd->inbuf is read-only */ 660 bd->inbuf = (void*)inbuf; /* cast away const-ness */ 661 bd->inbufCount = len; 662 } else 663 bd->inbuf = (unsigned char *)(bd + 1); 664 665 /* Init the CRC32 table (big endian) */ 666 667 crc32_filltable(bd->crc32Table, 1); 668 669 /* Setup for I/O error handling via longjmp */ 670 671 i = setjmp(bd->jmpbuf); 672 if (i) return i; 673 674 /* Ensure that file starts with "BZh['1'-'9']." */ 675 676 i = get_bits(bd, 32); 677 if ((unsigned)(i - BZh0 - 1) >= 9) return RETVAL_NOT_BZIP_DATA; 678 679 /* Fourth byte (ascii '1'-'9'), indicates block size in units of 100k of 680 uncompressed data. Allocate intermediate buffer for block. */ 681 682 bd->dbufSize = 100000 * (i - BZh0); 683 684 /* Cannot use xmalloc - may leak bd in NOFORK case! */ 685 bd->dbuf = malloc_or_warn(bd->dbufSize * sizeof(int)); 686 if (!bd->dbuf) { 687 free(bd); 688 xfunc_die(); 689 } 690 return RETVAL_OK; 691} 692 693void dealloc_bunzip(bunzip_data *bd) 694{ 695 free(bd->dbuf); 696 free(bd); 697} 698 699 700/* Decompress src_fd to dst_fd. Stops at end of bzip data, not end of file. */ 701 702USE_DESKTOP(long long) int 703unpack_bz2_stream(int src_fd, int dst_fd) 704{ 705 USE_DESKTOP(long long total_written = 0;) 706 char *outbuf; 707 bunzip_data *bd; 708 int i; 709 710 outbuf = xmalloc(IOBUF_SIZE); 711 i = start_bunzip(&bd, src_fd, NULL, 0); 712 if (!i) { 713 for (;;) { 714 i = read_bunzip(bd, outbuf, IOBUF_SIZE); 715 if (i <= 0) break; 716 if (i != safe_write(dst_fd, outbuf, i)) { 717 i = RETVAL_UNEXPECTED_OUTPUT_EOF; 718 break; 719 } 720 USE_DESKTOP(total_written += i;) 721 } 722 } 723 724 /* Check CRC and release memory */ 725 726 if (i == RETVAL_LAST_BLOCK) { 727 if (bd->headerCRC != bd->totalCRC) { 728 bb_error_msg("data integrity error when decompressing"); 729 } else { 730 i = RETVAL_OK; 731 } 732 } else if (i == RETVAL_UNEXPECTED_OUTPUT_EOF) { 733 bb_error_msg("compressed file ends unexpectedly"); 734 } else { 735 bb_error_msg("decompression failed"); 736 } 737 dealloc_bunzip(bd); 738 free(outbuf); 739 740 return i ? i : USE_DESKTOP(total_written) + 0; 741} 742 743#ifdef TESTING 744 745static char *const bunzip_errors[] = { 746 NULL, "Bad file checksum", "Not bzip data", 747 "Unexpected input EOF", "Unexpected output EOF", "Data error", 748 "Out of memory", "Obsolete (pre 0.9.5) bzip format not supported" 749}; 750 751/* Dumb little test thing, decompress stdin to stdout */ 752int main(int argc, char **argv) 753{ 754 int i = unpack_bz2_stream(0, 1); 755 char c; 756 757 if (i < 0) 758 fprintf(stderr,"%s\n", bunzip_errors[-i]); 759 else if (read(0, &c, 1)) 760 fprintf(stderr,"Trailing garbage ignored\n"); 761 return -i; 762} 763#endif 764