Contents of /trunk/mkinitrd-magellan/busybox/archival/libunarchive/decompress_bunzip2.c
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Fri Apr 24 18:33:46 2009 UTC (15 years ago) by niro
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Fri Apr 24 18:33:46 2009 UTC (15 years ago) by niro
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File size: 24571 byte(s)
-updated to busybox-1.13.4
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_SHORT_WRITE (-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 */ |
56 | struct group_data { |
57 | /* We have an extra slot at the end of limit[] for a sentinel 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 | * Found the most used member: |
65 | * cat this_file.c | sed -e 's/"/ /g' -e "s/'/ /g" | xargs -n1 \ |
66 | * | grep 'bd->' | sed 's/^.*bd->/bd->/' | sort | $PAGER |
67 | * and moved it (inbufBitCount) to offset 0. |
68 | */ |
69 | struct bunzip_data { |
70 | /* I/O tracking data (file handles, buffers, positions, etc.) */ |
71 | unsigned inbufBitCount, inbufBits; |
72 | int in_fd, out_fd, inbufCount, inbufPos /*, outbufPos*/; |
73 | unsigned char *inbuf /*,*outbuf*/; |
74 | |
75 | /* State for interrupting output loop */ |
76 | int writeCopies, writePos, writeRunCountdown, writeCount, writeCurrent; |
77 | |
78 | /* The CRC values stored in the block header and calculated from the data */ |
79 | uint32_t headerCRC, totalCRC, writeCRC; |
80 | |
81 | /* Intermediate buffer and its size (in bytes) */ |
82 | unsigned *dbuf, dbufSize; |
83 | |
84 | /* For I/O error handling */ |
85 | jmp_buf jmpbuf; |
86 | |
87 | /* Big things go last (register-relative addressing can be larger for big offsets) */ |
88 | uint32_t crc32Table[256]; |
89 | unsigned char selectors[32768]; /* nSelectors=15 bits */ |
90 | struct group_data groups[MAX_GROUPS]; /* Huffman coding tables */ |
91 | }; |
92 | /* typedef struct bunzip_data bunzip_data; -- done in .h file */ |
93 | |
94 | |
95 | /* Return the next nnn bits of input. All reads from the compressed input |
96 | are done through this function. All reads are big endian */ |
97 | |
98 | static unsigned get_bits(bunzip_data *bd, int bits_wanted) |
99 | { |
100 | unsigned bits = 0; |
101 | |
102 | /* If we need to get more data from the byte buffer, do so. (Loop getting |
103 | one byte at a time to enforce endianness and avoid unaligned access.) */ |
104 | while ((int)(bd->inbufBitCount) < bits_wanted) { |
105 | |
106 | /* If we need to read more data from file into byte buffer, do so */ |
107 | if (bd->inbufPos == bd->inbufCount) { |
108 | /* if "no input fd" case: in_fd == -1, read fails, we jump */ |
109 | bd->inbufCount = read(bd->in_fd, bd->inbuf, IOBUF_SIZE); |
110 | if (bd->inbufCount <= 0) |
111 | longjmp(bd->jmpbuf, RETVAL_UNEXPECTED_INPUT_EOF); |
112 | bd->inbufPos = 0; |
113 | } |
114 | |
115 | /* Avoid 32-bit overflow (dump bit buffer to top of output) */ |
116 | if (bd->inbufBitCount >= 24) { |
117 | bits = bd->inbufBits & ((1 << bd->inbufBitCount) - 1); |
118 | bits_wanted -= bd->inbufBitCount; |
119 | bits <<= bits_wanted; |
120 | bd->inbufBitCount = 0; |
121 | } |
122 | |
123 | /* Grab next 8 bits of input from buffer. */ |
124 | bd->inbufBits = (bd->inbufBits << 8) | bd->inbuf[bd->inbufPos++]; |
125 | bd->inbufBitCount += 8; |
126 | } |
127 | |
128 | /* Calculate result */ |
129 | bd->inbufBitCount -= bits_wanted; |
130 | bits |= (bd->inbufBits >> bd->inbufBitCount) & ((1 << bits_wanted) - 1); |
131 | |
132 | return bits; |
133 | } |
134 | |
135 | /* Unpacks the next block and sets up for the inverse burrows-wheeler step. */ |
136 | static int get_next_block(bunzip_data *bd) |
137 | { |
138 | struct group_data *hufGroup; |
139 | int dbufCount, nextSym, dbufSize, groupCount, *base, *limit, selector, |
140 | i, j, k, t, runPos, symCount, symTotal, nSelectors, byteCount[256]; |
141 | unsigned char uc, symToByte[256], mtfSymbol[256], *selectors; |
142 | unsigned *dbuf, origPtr; |
143 | |
144 | dbuf = bd->dbuf; |
145 | dbufSize = bd->dbufSize; |
146 | selectors = bd->selectors; |
147 | |
148 | /* Reset longjmp I/O error handling */ |
149 | i = setjmp(bd->jmpbuf); |
150 | if (i) return i; |
151 | |
152 | /* Read in header signature and CRC, then validate signature. |
153 | (last block signature means CRC is for whole file, return now) */ |
154 | i = get_bits(bd, 24); |
155 | j = get_bits(bd, 24); |
156 | bd->headerCRC = get_bits(bd, 32); |
157 | if ((i == 0x177245) && (j == 0x385090)) return RETVAL_LAST_BLOCK; |
158 | if ((i != 0x314159) || (j != 0x265359)) return RETVAL_NOT_BZIP_DATA; |
159 | |
160 | /* We can add support for blockRandomised if anybody complains. There was |
161 | some code for this in busybox 1.0.0-pre3, but nobody ever noticed that |
162 | it didn't actually work. */ |
163 | if (get_bits(bd, 1)) return RETVAL_OBSOLETE_INPUT; |
164 | origPtr = get_bits(bd, 24); |
165 | if ((int)origPtr > dbufSize) return RETVAL_DATA_ERROR; |
166 | |
167 | /* mapping table: if some byte values are never used (encoding things |
168 | like ascii text), the compression code removes the gaps to have fewer |
169 | symbols to deal with, and writes a sparse bitfield indicating which |
170 | values were present. We make a translation table to convert the symbols |
171 | back to the corresponding bytes. */ |
172 | t = get_bits(bd, 16); |
173 | symTotal = 0; |
174 | for (i = 0; i < 16; i++) { |
175 | if (t & (1 << (15-i))) { |
176 | k = get_bits(bd, 16); |
177 | for (j = 0; j < 16; j++) |
178 | if (k & (1 << (15-j))) |
179 | symToByte[symTotal++] = (16*i) + j; |
180 | } |
181 | } |
182 | |
183 | /* How many different Huffman coding groups does this block use? */ |
184 | groupCount = get_bits(bd, 3); |
185 | if (groupCount < 2 || groupCount > MAX_GROUPS) |
186 | return RETVAL_DATA_ERROR; |
187 | |
188 | /* nSelectors: Every GROUP_SIZE many symbols we select a new Huffman coding |
189 | group. Read in the group selector list, which is stored as MTF encoded |
190 | bit runs. (MTF=Move To Front, as each value is used it's moved to the |
191 | start of the list.) */ |
192 | nSelectors = get_bits(bd, 15); |
193 | if (!nSelectors) return RETVAL_DATA_ERROR; |
194 | for (i = 0; i < groupCount; i++) mtfSymbol[i] = i; |
195 | for (i = 0; i < nSelectors; i++) { |
196 | |
197 | /* Get next value */ |
198 | for (j = 0; get_bits(bd, 1); j++) |
199 | if (j >= groupCount) return RETVAL_DATA_ERROR; |
200 | |
201 | /* Decode MTF to get the next selector */ |
202 | uc = mtfSymbol[j]; |
203 | for (;j;j--) mtfSymbol[j] = mtfSymbol[j-1]; |
204 | mtfSymbol[0] = selectors[i] = uc; |
205 | } |
206 | |
207 | /* Read the Huffman coding tables for each group, which code for symTotal |
208 | literal symbols, plus two run symbols (RUNA, RUNB) */ |
209 | symCount = symTotal + 2; |
210 | for (j = 0; j < groupCount; j++) { |
211 | unsigned char length[MAX_SYMBOLS]; |
212 | /* 8 bits is ALMOST enough for temp[], see below */ |
213 | unsigned temp[MAX_HUFCODE_BITS+1]; |
214 | int minLen, maxLen, pp; |
215 | |
216 | /* Read Huffman code lengths for each symbol. They're stored in |
217 | a way similar to mtf; record a starting value for the first symbol, |
218 | and an offset from the previous value for everys symbol after that. |
219 | (Subtracting 1 before the loop and then adding it back at the end is |
220 | an optimization that makes the test inside the loop simpler: symbol |
221 | length 0 becomes negative, so an unsigned inequality catches it.) */ |
222 | t = get_bits(bd, 5) - 1; |
223 | for (i = 0; i < symCount; i++) { |
224 | for (;;) { |
225 | if ((unsigned)t > (MAX_HUFCODE_BITS-1)) |
226 | return RETVAL_DATA_ERROR; |
227 | |
228 | /* If first bit is 0, stop. Else second bit indicates whether |
229 | to increment or decrement the value. Optimization: grab 2 |
230 | bits and unget the second if the first was 0. */ |
231 | k = get_bits(bd, 2); |
232 | if (k < 2) { |
233 | bd->inbufBitCount++; |
234 | break; |
235 | } |
236 | |
237 | /* Add one if second bit 1, else subtract 1. Avoids if/else */ |
238 | t += (((k+1) & 2) - 1); |
239 | } |
240 | |
241 | /* Correct for the initial -1, to get the final symbol length */ |
242 | length[i] = t + 1; |
243 | } |
244 | |
245 | /* Find largest and smallest lengths in this group */ |
246 | minLen = maxLen = length[0]; |
247 | for (i = 1; i < symCount; i++) { |
248 | if (length[i] > maxLen) maxLen = length[i]; |
249 | else if (length[i] < minLen) minLen = length[i]; |
250 | } |
251 | |
252 | /* Calculate permute[], base[], and limit[] tables from length[]. |
253 | * |
254 | * permute[] is the lookup table for converting Huffman coded symbols |
255 | * into decoded symbols. base[] is the amount to subtract from the |
256 | * value of a Huffman symbol of a given length when using permute[]. |
257 | * |
258 | * limit[] indicates the largest numerical value a symbol with a given |
259 | * number of bits can have. This is how the Huffman codes can vary in |
260 | * length: each code with a value>limit[length] needs another bit. |
261 | */ |
262 | hufGroup = bd->groups + j; |
263 | hufGroup->minLen = minLen; |
264 | hufGroup->maxLen = maxLen; |
265 | |
266 | /* Note that minLen can't be smaller than 1, so we adjust the base |
267 | and limit array pointers so we're not always wasting the first |
268 | entry. We do this again when using them (during symbol decoding).*/ |
269 | base = hufGroup->base - 1; |
270 | limit = hufGroup->limit - 1; |
271 | |
272 | /* Calculate permute[]. Concurently, initialize temp[] and limit[]. */ |
273 | pp = 0; |
274 | for (i = minLen; i <= maxLen; i++) { |
275 | temp[i] = limit[i] = 0; |
276 | for (t = 0; t < symCount; t++) |
277 | if (length[t] == i) |
278 | hufGroup->permute[pp++] = t; |
279 | } |
280 | |
281 | /* Count symbols coded for at each bit length */ |
282 | /* NB: in pathological cases, temp[8] can end ip being 256. |
283 | * That's why uint8_t is too small for temp[]. */ |
284 | for (i = 0; i < symCount; i++) temp[length[i]]++; |
285 | |
286 | /* Calculate limit[] (the largest symbol-coding value at each bit |
287 | * length, which is (previous limit<<1)+symbols at this level), and |
288 | * base[] (number of symbols to ignore at each bit length, which is |
289 | * limit minus the cumulative count of symbols coded for already). */ |
290 | pp = t = 0; |
291 | for (i = minLen; i < maxLen; i++) { |
292 | pp += temp[i]; |
293 | |
294 | /* We read the largest possible symbol size and then unget bits |
295 | after determining how many we need, and those extra bits could |
296 | be set to anything. (They're noise from future symbols.) At |
297 | each level we're really only interested in the first few bits, |
298 | so here we set all the trailing to-be-ignored bits to 1 so they |
299 | don't affect the value>limit[length] comparison. */ |
300 | limit[i] = (pp << (maxLen - i)) - 1; |
301 | pp <<= 1; |
302 | t += temp[i]; |
303 | base[i+1] = pp - t; |
304 | } |
305 | limit[maxLen+1] = INT_MAX; /* Sentinel value for reading next sym. */ |
306 | limit[maxLen] = pp + temp[maxLen] - 1; |
307 | base[minLen] = 0; |
308 | } |
309 | |
310 | /* We've finished reading and digesting the block header. Now read this |
311 | block's Huffman coded symbols from the file and undo the Huffman coding |
312 | and run length encoding, saving the result into dbuf[dbufCount++] = uc */ |
313 | |
314 | /* Initialize symbol occurrence counters and symbol Move To Front table */ |
315 | memset(byteCount, 0, sizeof(byteCount)); /* smaller, maybe slower? */ |
316 | for (i = 0; i < 256; i++) { |
317 | //byteCount[i] = 0; |
318 | mtfSymbol[i] = (unsigned char)i; |
319 | } |
320 | |
321 | /* Loop through compressed symbols. */ |
322 | |
323 | runPos = dbufCount = selector = 0; |
324 | for (;;) { |
325 | |
326 | /* Fetch next Huffman coding group from list. */ |
327 | symCount = GROUP_SIZE - 1; |
328 | if (selector >= nSelectors) return RETVAL_DATA_ERROR; |
329 | hufGroup = bd->groups + selectors[selector++]; |
330 | base = hufGroup->base - 1; |
331 | limit = hufGroup->limit - 1; |
332 | continue_this_group: |
333 | |
334 | /* Read next Huffman-coded symbol. */ |
335 | |
336 | /* Note: It is far cheaper to read maxLen bits and back up than it is |
337 | to read minLen bits and then an additional bit at a time, testing |
338 | as we go. Because there is a trailing last block (with file CRC), |
339 | there is no danger of the overread causing an unexpected EOF for a |
340 | valid compressed file. As a further optimization, we do the read |
341 | inline (falling back to a call to get_bits if the buffer runs |
342 | dry). The following (up to got_huff_bits:) is equivalent to |
343 | j = get_bits(bd, hufGroup->maxLen); |
344 | */ |
345 | while ((int)(bd->inbufBitCount) < hufGroup->maxLen) { |
346 | if (bd->inbufPos == bd->inbufCount) { |
347 | j = get_bits(bd, hufGroup->maxLen); |
348 | goto got_huff_bits; |
349 | } |
350 | bd->inbufBits = (bd->inbufBits << 8) | bd->inbuf[bd->inbufPos++]; |
351 | bd->inbufBitCount += 8; |
352 | }; |
353 | bd->inbufBitCount -= hufGroup->maxLen; |
354 | j = (bd->inbufBits >> bd->inbufBitCount) & ((1 << hufGroup->maxLen) - 1); |
355 | |
356 | got_huff_bits: |
357 | |
358 | /* Figure how how many bits are in next symbol and unget extras */ |
359 | i = hufGroup->minLen; |
360 | while (j > limit[i]) ++i; |
361 | bd->inbufBitCount += (hufGroup->maxLen - i); |
362 | |
363 | /* Huffman decode value to get nextSym (with bounds checking) */ |
364 | if (i > hufGroup->maxLen) |
365 | return RETVAL_DATA_ERROR; |
366 | j = (j >> (hufGroup->maxLen - i)) - base[i]; |
367 | if ((unsigned)j >= MAX_SYMBOLS) |
368 | return RETVAL_DATA_ERROR; |
369 | nextSym = hufGroup->permute[j]; |
370 | |
371 | /* We have now decoded the symbol, which indicates either a new literal |
372 | byte, or a repeated run of the most recent literal byte. First, |
373 | check if nextSym indicates a repeated run, and if so loop collecting |
374 | how many times to repeat the last literal. */ |
375 | if ((unsigned)nextSym <= SYMBOL_RUNB) { /* RUNA or RUNB */ |
376 | |
377 | /* If this is the start of a new run, zero out counter */ |
378 | if (!runPos) { |
379 | runPos = 1; |
380 | t = 0; |
381 | } |
382 | |
383 | /* Neat trick that saves 1 symbol: instead of or-ing 0 or 1 at |
384 | each bit position, add 1 or 2 instead. For example, |
385 | 1011 is 1<<0 + 1<<1 + 2<<2. 1010 is 2<<0 + 2<<1 + 1<<2. |
386 | You can make any bit pattern that way using 1 less symbol than |
387 | the basic or 0/1 method (except all bits 0, which would use no |
388 | symbols, but a run of length 0 doesn't mean anything in this |
389 | context). Thus space is saved. */ |
390 | t += (runPos << nextSym); /* +runPos if RUNA; +2*runPos if RUNB */ |
391 | if (runPos < dbufSize) runPos <<= 1; |
392 | goto end_of_huffman_loop; |
393 | } |
394 | |
395 | /* When we hit the first non-run symbol after a run, we now know |
396 | how many times to repeat the last literal, so append that many |
397 | copies to our buffer of decoded symbols (dbuf) now. (The last |
398 | literal used is the one at the head of the mtfSymbol array.) */ |
399 | if (runPos) { |
400 | runPos = 0; |
401 | if (dbufCount + t >= dbufSize) return RETVAL_DATA_ERROR; |
402 | |
403 | uc = symToByte[mtfSymbol[0]]; |
404 | byteCount[uc] += t; |
405 | while (t--) dbuf[dbufCount++] = uc; |
406 | } |
407 | |
408 | /* Is this the terminating symbol? */ |
409 | if (nextSym > symTotal) break; |
410 | |
411 | /* At this point, nextSym indicates a new literal character. Subtract |
412 | one to get the position in the MTF array at which this literal is |
413 | currently to be found. (Note that the result can't be -1 or 0, |
414 | because 0 and 1 are RUNA and RUNB. But another instance of the |
415 | first symbol in the mtf array, position 0, would have been handled |
416 | as part of a run above. Therefore 1 unused mtf position minus |
417 | 2 non-literal nextSym values equals -1.) */ |
418 | if (dbufCount >= dbufSize) return RETVAL_DATA_ERROR; |
419 | i = nextSym - 1; |
420 | uc = mtfSymbol[i]; |
421 | |
422 | /* Adjust the MTF array. Since we typically expect to move only a |
423 | * small number of symbols, and are bound by 256 in any case, using |
424 | * memmove here would typically be bigger and slower due to function |
425 | * call overhead and other assorted setup costs. */ |
426 | do { |
427 | mtfSymbol[i] = mtfSymbol[i-1]; |
428 | } while (--i); |
429 | mtfSymbol[0] = uc; |
430 | uc = symToByte[uc]; |
431 | |
432 | /* We have our literal byte. Save it into dbuf. */ |
433 | byteCount[uc]++; |
434 | dbuf[dbufCount++] = (unsigned)uc; |
435 | |
436 | /* Skip group initialization if we're not done with this group. Done |
437 | * this way to avoid compiler warning. */ |
438 | end_of_huffman_loop: |
439 | if (symCount--) goto continue_this_group; |
440 | } |
441 | |
442 | /* At this point, we've read all the Huffman-coded symbols (and repeated |
443 | runs) for this block from the input stream, and decoded them into the |
444 | intermediate buffer. There are dbufCount many decoded bytes in dbuf[]. |
445 | Now undo the Burrows-Wheeler transform on dbuf. |
446 | See http://dogma.net/markn/articles/bwt/bwt.htm |
447 | */ |
448 | |
449 | /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */ |
450 | j = 0; |
451 | for (i = 0; i < 256; i++) { |
452 | k = j + byteCount[i]; |
453 | byteCount[i] = j; |
454 | j = k; |
455 | } |
456 | |
457 | /* Figure out what order dbuf would be in if we sorted it. */ |
458 | for (i = 0; i < dbufCount; i++) { |
459 | uc = (unsigned char)(dbuf[i] & 0xff); |
460 | dbuf[byteCount[uc]] |= (i << 8); |
461 | byteCount[uc]++; |
462 | } |
463 | |
464 | /* Decode first byte by hand to initialize "previous" byte. Note that it |
465 | doesn't get output, and if the first three characters are identical |
466 | it doesn't qualify as a run (hence writeRunCountdown=5). */ |
467 | if (dbufCount) { |
468 | if ((int)origPtr >= dbufCount) return RETVAL_DATA_ERROR; |
469 | bd->writePos = dbuf[origPtr]; |
470 | bd->writeCurrent = (unsigned char)(bd->writePos & 0xff); |
471 | bd->writePos >>= 8; |
472 | bd->writeRunCountdown = 5; |
473 | } |
474 | bd->writeCount = dbufCount; |
475 | |
476 | return RETVAL_OK; |
477 | } |
478 | |
479 | /* Undo burrows-wheeler transform on intermediate buffer to produce output. |
480 | If start_bunzip was initialized with out_fd=-1, then up to len bytes of |
481 | data are written to outbuf. Return value is number of bytes written or |
482 | error (all errors are negative numbers). If out_fd!=-1, outbuf and len |
483 | are ignored, data is written to out_fd and return is RETVAL_OK or error. |
484 | */ |
485 | int FAST_FUNC read_bunzip(bunzip_data *bd, char *outbuf, int len) |
486 | { |
487 | const unsigned *dbuf; |
488 | int pos, current, previous, gotcount; |
489 | |
490 | /* If last read was short due to end of file, return last block now */ |
491 | if (bd->writeCount < 0) return bd->writeCount; |
492 | |
493 | gotcount = 0; |
494 | dbuf = bd->dbuf; |
495 | pos = bd->writePos; |
496 | current = bd->writeCurrent; |
497 | |
498 | /* We will always have pending decoded data to write into the output |
499 | buffer unless this is the very first call (in which case we haven't |
500 | Huffman-decoded a block into the intermediate buffer yet). */ |
501 | if (bd->writeCopies) { |
502 | |
503 | /* Inside the loop, writeCopies means extra copies (beyond 1) */ |
504 | --bd->writeCopies; |
505 | |
506 | /* Loop outputting bytes */ |
507 | for (;;) { |
508 | |
509 | /* If the output buffer is full, snapshot state and return */ |
510 | if (gotcount >= len) { |
511 | bd->writePos = pos; |
512 | bd->writeCurrent = current; |
513 | bd->writeCopies++; |
514 | return len; |
515 | } |
516 | |
517 | /* Write next byte into output buffer, updating CRC */ |
518 | outbuf[gotcount++] = current; |
519 | bd->writeCRC = (bd->writeCRC << 8) |
520 | ^ bd->crc32Table[(bd->writeCRC >> 24) ^ current]; |
521 | |
522 | /* Loop now if we're outputting multiple copies of this byte */ |
523 | if (bd->writeCopies) { |
524 | --bd->writeCopies; |
525 | continue; |
526 | } |
527 | decode_next_byte: |
528 | if (!bd->writeCount--) break; |
529 | /* Follow sequence vector to undo Burrows-Wheeler transform */ |
530 | previous = current; |
531 | pos = dbuf[pos]; |
532 | current = pos & 0xff; |
533 | pos >>= 8; |
534 | |
535 | /* After 3 consecutive copies of the same byte, the 4th |
536 | * is a repeat count. We count down from 4 instead |
537 | * of counting up because testing for non-zero is faster */ |
538 | if (--bd->writeRunCountdown) { |
539 | if (current != previous) |
540 | bd->writeRunCountdown = 4; |
541 | } else { |
542 | |
543 | /* We have a repeated run, this byte indicates the count */ |
544 | bd->writeCopies = current; |
545 | current = previous; |
546 | bd->writeRunCountdown = 5; |
547 | |
548 | /* Sometimes there are just 3 bytes (run length 0) */ |
549 | if (!bd->writeCopies) goto decode_next_byte; |
550 | |
551 | /* Subtract the 1 copy we'd output anyway to get extras */ |
552 | --bd->writeCopies; |
553 | } |
554 | } |
555 | |
556 | /* Decompression of this block completed successfully */ |
557 | bd->writeCRC = ~bd->writeCRC; |
558 | bd->totalCRC = ((bd->totalCRC << 1) | (bd->totalCRC >> 31)) ^ bd->writeCRC; |
559 | |
560 | /* If this block had a CRC error, force file level CRC error. */ |
561 | if (bd->writeCRC != bd->headerCRC) { |
562 | bd->totalCRC = bd->headerCRC + 1; |
563 | return RETVAL_LAST_BLOCK; |
564 | } |
565 | } |
566 | |
567 | /* Refill the intermediate buffer by Huffman-decoding next block of input */ |
568 | /* (previous is just a convenient unused temp variable here) */ |
569 | previous = get_next_block(bd); |
570 | if (previous) { |
571 | bd->writeCount = previous; |
572 | return (previous != RETVAL_LAST_BLOCK) ? previous : gotcount; |
573 | } |
574 | bd->writeCRC = ~0; |
575 | pos = bd->writePos; |
576 | current = bd->writeCurrent; |
577 | goto decode_next_byte; |
578 | } |
579 | |
580 | /* Allocate the structure, read file header. If in_fd==-1, inbuf must contain |
581 | a complete bunzip file (len bytes long). If in_fd!=-1, inbuf and len are |
582 | ignored, and data is read from file handle into temporary buffer. */ |
583 | |
584 | /* Because bunzip2 is used for help text unpacking, and because bb_show_usage() |
585 | should work for NOFORK applets too, we must be extremely careful to not leak |
586 | any allocations! */ |
587 | int FAST_FUNC start_bunzip(bunzip_data **bdp, int in_fd, const unsigned char *inbuf, |
588 | int len) |
589 | { |
590 | bunzip_data *bd; |
591 | unsigned i; |
592 | enum { |
593 | BZh0 = ('B' << 24) + ('Z' << 16) + ('h' << 8) + '0', |
594 | h0 = ('h' << 8) + '0', |
595 | }; |
596 | |
597 | /* Figure out how much data to allocate */ |
598 | i = sizeof(bunzip_data); |
599 | if (in_fd != -1) i += IOBUF_SIZE; |
600 | |
601 | /* Allocate bunzip_data. Most fields initialize to zero. */ |
602 | bd = *bdp = xzalloc(i); |
603 | |
604 | /* Setup input buffer */ |
605 | bd->in_fd = in_fd; |
606 | if (-1 == in_fd) { |
607 | /* in this case, bd->inbuf is read-only */ |
608 | bd->inbuf = (void*)inbuf; /* cast away const-ness */ |
609 | bd->inbufCount = len; |
610 | } else |
611 | bd->inbuf = (unsigned char *)(bd + 1); |
612 | |
613 | /* Init the CRC32 table (big endian) */ |
614 | crc32_filltable(bd->crc32Table, 1); |
615 | |
616 | /* Setup for I/O error handling via longjmp */ |
617 | i = setjmp(bd->jmpbuf); |
618 | if (i) return i; |
619 | |
620 | /* Ensure that file starts with "BZh['1'-'9']." */ |
621 | /* Update: now caller verifies 1st two bytes, makes .gz/.bz2 |
622 | * integration easier */ |
623 | /* was: */ |
624 | /* i = get_bits(bd, 32); */ |
625 | /* if ((unsigned)(i - BZh0 - 1) >= 9) return RETVAL_NOT_BZIP_DATA; */ |
626 | i = get_bits(bd, 16); |
627 | if ((unsigned)(i - h0 - 1) >= 9) return RETVAL_NOT_BZIP_DATA; |
628 | |
629 | /* Fourth byte (ascii '1'-'9') indicates block size in units of 100k of |
630 | uncompressed data. Allocate intermediate buffer for block. */ |
631 | /* bd->dbufSize = 100000 * (i - BZh0); */ |
632 | bd->dbufSize = 100000 * (i - h0); |
633 | |
634 | /* Cannot use xmalloc - may leak bd in NOFORK case! */ |
635 | bd->dbuf = malloc_or_warn(bd->dbufSize * sizeof(int)); |
636 | if (!bd->dbuf) { |
637 | free(bd); |
638 | xfunc_die(); |
639 | } |
640 | return RETVAL_OK; |
641 | } |
642 | |
643 | void FAST_FUNC dealloc_bunzip(bunzip_data *bd) |
644 | { |
645 | free(bd->dbuf); |
646 | free(bd); |
647 | } |
648 | |
649 | |
650 | /* Decompress src_fd to dst_fd. Stops at end of bzip data, not end of file. */ |
651 | USE_DESKTOP(long long) int FAST_FUNC |
652 | unpack_bz2_stream(int src_fd, int dst_fd) |
653 | { |
654 | USE_DESKTOP(long long total_written = 0;) |
655 | char *outbuf; |
656 | bunzip_data *bd; |
657 | int i; |
658 | |
659 | outbuf = xmalloc(IOBUF_SIZE); |
660 | i = start_bunzip(&bd, src_fd, NULL, 0); |
661 | if (!i) { |
662 | for (;;) { |
663 | i = read_bunzip(bd, outbuf, IOBUF_SIZE); |
664 | if (i <= 0) break; |
665 | if (i != full_write(dst_fd, outbuf, i)) { |
666 | i = RETVAL_SHORT_WRITE; |
667 | break; |
668 | } |
669 | USE_DESKTOP(total_written += i;) |
670 | } |
671 | } |
672 | |
673 | /* Check CRC and release memory */ |
674 | |
675 | if (i == RETVAL_LAST_BLOCK) { |
676 | if (bd->headerCRC != bd->totalCRC) { |
677 | bb_error_msg("CRC error"); |
678 | } else { |
679 | i = RETVAL_OK; |
680 | } |
681 | } else if (i == RETVAL_SHORT_WRITE) { |
682 | bb_error_msg("short write"); |
683 | } else { |
684 | bb_error_msg("bunzip error %d", i); |
685 | } |
686 | dealloc_bunzip(bd); |
687 | free(outbuf); |
688 | |
689 | return i ? i : USE_DESKTOP(total_written) + 0; |
690 | } |
691 | |
692 | USE_DESKTOP(long long) int FAST_FUNC |
693 | unpack_bz2_stream_prime(int src_fd, int dst_fd) |
694 | { |
695 | unsigned char magic[2]; |
696 | xread(src_fd, magic, 2); |
697 | if (magic[0] != 'B' || magic[1] != 'Z') { |
698 | bb_error_msg_and_die("invalid magic"); |
699 | } |
700 | return unpack_bz2_stream(src_fd, dst_fd); |
701 | } |
702 | |
703 | #ifdef TESTING |
704 | |
705 | static char *const bunzip_errors[] = { |
706 | NULL, "Bad file checksum", "Not bzip data", |
707 | "Unexpected input EOF", "Unexpected output EOF", "Data error", |
708 | "Out of memory", "Obsolete (pre 0.9.5) bzip format not supported" |
709 | }; |
710 | |
711 | /* Dumb little test thing, decompress stdin to stdout */ |
712 | int main(int argc, char **argv) |
713 | { |
714 | int i; |
715 | char c; |
716 | |
717 | int i = unpack_bz2_stream_prime(0, 1); |
718 | if (i < 0) |
719 | fprintf(stderr, "%s\n", bunzip_errors[-i]); |
720 | else if (read(STDIN_FILENO, &c, 1)) |
721 | fprintf(stderr, "Trailing garbage ignored\n"); |
722 | return -i; |
723 | } |
724 | #endif |