Annotation of /trunk/mkinitrd-magellan/busybox/archival/libunarchive/decompress_bunzip2.c
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Sat Sep 1 22:45:15 2007 UTC (16 years, 8 months ago) by niro
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Sat Sep 1 22:45:15 2007 UTC (16 years, 8 months ago) by niro
File MIME type: text/plain
File size: 22540 byte(s)
-import if magellan mkinitrd; it is a fork of redhats mkinitrd-5.0.8 with all magellan patches and features; deprecates magellan-src/mkinitrd
1 | niro | 532 | /* 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 */ | ||
56 | struct 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 | |||
65 | typedef struct { | ||
66 | /* State for interrupting output loop */ | ||
67 | |||
68 | int writeCopies,writePos,writeRunCountdown,writeCount,writeCurrent; | ||
69 | |||
70 | /* I/O tracking data (file handles, buffers, positions, etc.) */ | ||
71 | |||
72 | int in_fd,out_fd,inbufCount,inbufPos /*,outbufPos*/; | ||
73 | unsigned char *inbuf /*,*outbuf*/; | ||
74 | unsigned int inbufBitCount, inbufBits; | ||
75 | |||
76 | /* The CRC values stored in the block header and calculated from the data */ | ||
77 | |||
78 | uint32_t headerCRC, totalCRC, writeCRC; | ||
79 | uint32_t *crc32Table; | ||
80 | /* Intermediate buffer and its size (in bytes) */ | ||
81 | |||
82 | unsigned int *dbuf, dbufSize; | ||
83 | |||
84 | /* These things are a bit too big to go on the stack */ | ||
85 | |||
86 | unsigned char selectors[32768]; /* nSelectors=15 bits */ | ||
87 | struct group_data groups[MAX_GROUPS]; /* Huffman coding tables */ | ||
88 | |||
89 | /* For I/O error handling */ | ||
90 | |||
91 | jmp_buf jmpbuf; | ||
92 | } bunzip_data; | ||
93 | |||
94 | /* Return the next nnn bits of input. All reads from the compressed input | ||
95 | are done through this function. All reads are big endian */ | ||
96 | |||
97 | static unsigned int get_bits(bunzip_data *bd, char bits_wanted) | ||
98 | { | ||
99 | unsigned int bits=0; | ||
100 | |||
101 | /* If we need to get more data from the byte buffer, do so. (Loop getting | ||
102 | one byte at a time to enforce endianness and avoid unaligned access.) */ | ||
103 | |||
104 | while (bd->inbufBitCount<bits_wanted) { | ||
105 | |||
106 | /* If we need to read more data from file into byte buffer, do so */ | ||
107 | |||
108 | if(bd->inbufPos==bd->inbufCount) { | ||
109 | if((bd->inbufCount = read(bd->in_fd, bd->inbuf, IOBUF_SIZE)) <= 0) | ||
110 | longjmp(bd->jmpbuf,RETVAL_UNEXPECTED_INPUT_EOF); | ||
111 | bd->inbufPos=0; | ||
112 | } | ||
113 | |||
114 | /* Avoid 32-bit overflow (dump bit buffer to top of output) */ | ||
115 | |||
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 | |||
125 | bd->inbufBits=(bd->inbufBits<<8)|bd->inbuf[bd->inbufPos++]; | ||
126 | bd->inbufBitCount+=8; | ||
127 | } | ||
128 | |||
129 | /* Calculate result */ | ||
130 | |||
131 | bd->inbufBitCount-=bits_wanted; | ||
132 | bits|=(bd->inbufBits>>bd->inbufBitCount)&((1<<bits_wanted)-1); | ||
133 | |||
134 | return bits; | ||
135 | } | ||
136 | |||
137 | /* Unpacks the next block and sets up for the inverse burrows-wheeler step. */ | ||
138 | |||
139 | static int get_next_block(bunzip_data *bd) | ||
140 | { | ||
141 | struct group_data *hufGroup; | ||
142 | int dbufCount,nextSym,dbufSize,groupCount,*base,*limit,selector, | ||
143 | i,j,k,t,runPos,symCount,symTotal,nSelectors,byteCount[256]; | ||
144 | unsigned char uc, symToByte[256], mtfSymbol[256], *selectors; | ||
145 | unsigned int *dbuf,origPtr; | ||
146 | |||
147 | dbuf=bd->dbuf; | ||
148 | dbufSize=bd->dbufSize; | ||
149 | selectors=bd->selectors; | ||
150 | |||
151 | /* Reset longjmp I/O error handling */ | ||
152 | |||
153 | i=setjmp(bd->jmpbuf); | ||
154 | if (i) return i; | ||
155 | |||
156 | /* Read in header signature and CRC, then validate signature. | ||
157 | (last block signature means CRC is for whole file, return now) */ | ||
158 | |||
159 | i = get_bits(bd,24); | ||
160 | j = get_bits(bd,24); | ||
161 | bd->headerCRC=get_bits(bd,32); | ||
162 | if ((i == 0x177245) && (j == 0x385090)) return RETVAL_LAST_BLOCK; | ||
163 | if ((i != 0x314159) || (j != 0x265359)) return RETVAL_NOT_BZIP_DATA; | ||
164 | |||
165 | /* We can add support for blockRandomised if anybody complains. There was | ||
166 | some code for this in busybox 1.0.0-pre3, but nobody ever noticed that | ||
167 | it didn't actually work. */ | ||
168 | |||
169 | if (get_bits(bd,1)) return RETVAL_OBSOLETE_INPUT; | ||
170 | if ((origPtr=get_bits(bd,24)) > 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))) symToByte[symTotal++]=(16*i)+j; | ||
185 | } | ||
186 | } | ||
187 | |||
188 | /* How many different Huffman coding groups does this block use? */ | ||
189 | |||
190 | groupCount=get_bits(bd,3); | ||
191 | if (groupCount<2 || groupCount>MAX_GROUPS) return RETVAL_DATA_ERROR; | ||
192 | |||
193 | /* nSelectors: Every GROUP_SIZE many symbols we select a new Huffman coding | ||
194 | group. Read in the group selector list, which is stored as MTF encoded | ||
195 | bit runs. (MTF=Move To Front, as each value is used it's moved to the | ||
196 | start of the list.) */ | ||
197 | |||
198 | if(!(nSelectors=get_bits(bd, 15))) return RETVAL_DATA_ERROR; | ||
199 | for (i=0; i<groupCount; i++) mtfSymbol[i] = i; | ||
200 | for (i=0; i<nSelectors; i++) { | ||
201 | |||
202 | /* Get next value */ | ||
203 | |||
204 | for (j=0;get_bits(bd,1);j++) if (j>=groupCount) return RETVAL_DATA_ERROR; | ||
205 | |||
206 | /* Decode MTF to get the next selector */ | ||
207 | |||
208 | uc = mtfSymbol[j]; | ||
209 | for (;j;j--) mtfSymbol[j] = mtfSymbol[j-1]; | ||
210 | mtfSymbol[0]=selectors[i]=uc; | ||
211 | } | ||
212 | |||
213 | /* Read the Huffman coding tables for each group, which code for symTotal | ||
214 | literal symbols, plus two run symbols (RUNA, RUNB) */ | ||
215 | |||
216 | symCount=symTotal+2; | ||
217 | for (j=0; j<groupCount; j++) { | ||
218 | unsigned char length[MAX_SYMBOLS],temp[MAX_HUFCODE_BITS+1]; | ||
219 | int minLen, maxLen, pp; | ||
220 | |||
221 | /* Read Huffman code lengths for each symbol. They're stored in | ||
222 | a way similar to mtf; record a starting value for the first symbol, | ||
223 | and an offset from the previous value for everys symbol after that. | ||
224 | (Subtracting 1 before the loop and then adding it back at the end is | ||
225 | an optimization that makes the test inside the loop simpler: symbol | ||
226 | length 0 becomes negative, so an unsigned inequality catches it.) */ | ||
227 | |||
228 | t=get_bits(bd, 5)-1; | ||
229 | for (i = 0; i < symCount; i++) { | ||
230 | for (;;) { | ||
231 | if (((unsigned)t) > (MAX_HUFCODE_BITS-1)) | ||
232 | return RETVAL_DATA_ERROR; | ||
233 | |||
234 | /* If first bit is 0, stop. Else second bit indicates whether | ||
235 | to increment or decrement the value. Optimization: grab 2 | ||
236 | bits and unget the second if the first was 0. */ | ||
237 | |||
238 | k = get_bits(bd,2); | ||
239 | if (k < 2) { | ||
240 | bd->inbufBitCount++; | ||
241 | break; | ||
242 | } | ||
243 | |||
244 | /* Add one if second bit 1, else subtract 1. Avoids if/else */ | ||
245 | |||
246 | t+=(((k+1)&2)-1); | ||
247 | } | ||
248 | |||
249 | /* Correct for the initial -1, to get the final symbol length */ | ||
250 | |||
251 | length[i]=t+1; | ||
252 | } | ||
253 | |||
254 | /* Find largest and smallest lengths in this group */ | ||
255 | |||
256 | minLen=maxLen=length[0]; | ||
257 | for (i = 1; i < symCount; i++) { | ||
258 | if(length[i] > maxLen) maxLen = length[i]; | ||
259 | else if(length[i] < minLen) minLen = length[i]; | ||
260 | } | ||
261 | |||
262 | /* Calculate permute[], base[], and limit[] tables from length[]. | ||
263 | * | ||
264 | * permute[] is the lookup table for converting Huffman coded symbols | ||
265 | * into decoded symbols. base[] is the amount to subtract from the | ||
266 | * value of a Huffman symbol of a given length when using permute[]. | ||
267 | * | ||
268 | * limit[] indicates the largest numerical value a symbol with a given | ||
269 | * number of bits can have. This is how the Huffman codes can vary in | ||
270 | * length: each code with a value>limit[length] needs another bit. | ||
271 | */ | ||
272 | |||
273 | hufGroup=bd->groups+j; | ||
274 | hufGroup->minLen = minLen; | ||
275 | hufGroup->maxLen = maxLen; | ||
276 | |||
277 | /* Note that minLen can't be smaller than 1, so we adjust the base | ||
278 | and limit array pointers so we're not always wasting the first | ||
279 | entry. We do this again when using them (during symbol decoding).*/ | ||
280 | |||
281 | base=hufGroup->base-1; | ||
282 | limit=hufGroup->limit-1; | ||
283 | |||
284 | /* Calculate permute[]. Concurently, initialize temp[] and limit[]. */ | ||
285 | |||
286 | pp=0; | ||
287 | for (i=minLen;i<=maxLen;i++) { | ||
288 | temp[i]=limit[i]=0; | ||
289 | for (t=0;t<symCount;t++) | ||
290 | if(length[t]==i) hufGroup->permute[pp++] = t; | ||
291 | } | ||
292 | |||
293 | /* Count symbols coded for at each bit length */ | ||
294 | |||
295 | for (i=0;i<symCount;i++) temp[length[i]]++; | ||
296 | |||
297 | /* Calculate limit[] (the largest symbol-coding value at each bit | ||
298 | * length, which is (previous limit<<1)+symbols at this level), and | ||
299 | * base[] (number of symbols to ignore at each bit length, which is | ||
300 | * limit minus the cumulative count of symbols coded for already). */ | ||
301 | |||
302 | pp=t=0; | ||
303 | for (i=minLen; i<maxLen; i++) { | ||
304 | pp+=temp[i]; | ||
305 | |||
306 | /* We read the largest possible symbol size and then unget bits | ||
307 | after determining how many we need, and those extra bits could | ||
308 | be set to anything. (They're noise from future symbols.) At | ||
309 | each level we're really only interested in the first few bits, | ||
310 | so here we set all the trailing to-be-ignored bits to 1 so they | ||
311 | don't affect the value>limit[length] comparison. */ | ||
312 | |||
313 | limit[i]= (pp << (maxLen - i)) - 1; | ||
314 | pp<<=1; | ||
315 | base[i+1]=pp-(t+=temp[i]); | ||
316 | } | ||
317 | limit[maxLen+1] = INT_MAX; /* Sentinal value for reading next sym. */ | ||
318 | limit[maxLen]=pp+temp[maxLen]-1; | ||
319 | base[minLen]=0; | ||
320 | } | ||
321 | |||
322 | /* We've finished reading and digesting the block header. Now read this | ||
323 | block's Huffman coded symbols from the file and undo the Huffman coding | ||
324 | and run length encoding, saving the result into dbuf[dbufCount++]=uc */ | ||
325 | |||
326 | /* Initialize symbol occurrence counters and symbol Move To Front table */ | ||
327 | |||
328 | for (i=0;i<256;i++) { | ||
329 | byteCount[i] = 0; | ||
330 | mtfSymbol[i]=(unsigned char)i; | ||
331 | } | ||
332 | |||
333 | /* Loop through compressed symbols. */ | ||
334 | |||
335 | runPos=dbufCount=selector=0; | ||
336 | for (;;) { | ||
337 | |||
338 | /* fetch next Huffman coding group from list. */ | ||
339 | |||
340 | symCount=GROUP_SIZE-1; | ||
341 | if(selector>=nSelectors) return RETVAL_DATA_ERROR; | ||
342 | hufGroup=bd->groups+selectors[selector++]; | ||
343 | base=hufGroup->base-1; | ||
344 | limit=hufGroup->limit-1; | ||
345 | continue_this_group: | ||
346 | |||
347 | /* Read next Huffman-coded symbol. */ | ||
348 | |||
349 | /* Note: It is far cheaper to read maxLen bits and back up than it is | ||
350 | to read minLen bits and then an additional bit at a time, testing | ||
351 | as we go. Because there is a trailing last block (with file CRC), | ||
352 | there is no danger of the overread causing an unexpected EOF for a | ||
353 | valid compressed file. As a further optimization, we do the read | ||
354 | inline (falling back to a call to get_bits if the buffer runs | ||
355 | dry). The following (up to got_huff_bits:) is equivalent to | ||
356 | j=get_bits(bd,hufGroup->maxLen); | ||
357 | */ | ||
358 | |||
359 | while (bd->inbufBitCount<hufGroup->maxLen) { | ||
360 | if(bd->inbufPos==bd->inbufCount) { | ||
361 | j = get_bits(bd,hufGroup->maxLen); | ||
362 | goto got_huff_bits; | ||
363 | } | ||
364 | bd->inbufBits=(bd->inbufBits<<8)|bd->inbuf[bd->inbufPos++]; | ||
365 | bd->inbufBitCount+=8; | ||
366 | }; | ||
367 | bd->inbufBitCount-=hufGroup->maxLen; | ||
368 | j = (bd->inbufBits>>bd->inbufBitCount)&((1<<hufGroup->maxLen)-1); | ||
369 | |||
370 | got_huff_bits: | ||
371 | |||
372 | /* Figure how how many bits are in next symbol and unget extras */ | ||
373 | |||
374 | i=hufGroup->minLen; | ||
375 | while (j>limit[i]) ++i; | ||
376 | bd->inbufBitCount += (hufGroup->maxLen - i); | ||
377 | |||
378 | /* Huffman decode value to get nextSym (with bounds checking) */ | ||
379 | |||
380 | if ((i > hufGroup->maxLen) | ||
381 | || (((unsigned)(j=(j>>(hufGroup->maxLen-i))-base[i])) | ||
382 | >= MAX_SYMBOLS)) | ||
383 | return RETVAL_DATA_ERROR; | ||
384 | nextSym = hufGroup->permute[j]; | ||
385 | |||
386 | /* We have now decoded the symbol, which indicates either a new literal | ||
387 | byte, or a repeated run of the most recent literal byte. First, | ||
388 | check if nextSym indicates a repeated run, and if so loop collecting | ||
389 | how many times to repeat the last literal. */ | ||
390 | |||
391 | if (((unsigned)nextSym) <= SYMBOL_RUNB) { /* RUNA or RUNB */ | ||
392 | |||
393 | /* If this is the start of a new run, zero out counter */ | ||
394 | |||
395 | if(!runPos) { | ||
396 | runPos = 1; | ||
397 | t = 0; | ||
398 | } | ||
399 | |||
400 | /* Neat trick that saves 1 symbol: instead of or-ing 0 or 1 at | ||
401 | each bit position, add 1 or 2 instead. For example, | ||
402 | 1011 is 1<<0 + 1<<1 + 2<<2. 1010 is 2<<0 + 2<<1 + 1<<2. | ||
403 | You can make any bit pattern that way using 1 less symbol than | ||
404 | the basic or 0/1 method (except all bits 0, which would use no | ||
405 | symbols, but a run of length 0 doesn't mean anything in this | ||
406 | context). Thus space is saved. */ | ||
407 | |||
408 | t += (runPos << nextSym); /* +runPos if RUNA; +2*runPos if RUNB */ | ||
409 | if(runPos < dbufSize) runPos <<= 1; | ||
410 | goto end_of_huffman_loop; | ||
411 | } | ||
412 | |||
413 | /* When we hit the first non-run symbol after a run, we now know | ||
414 | how many times to repeat the last literal, so append that many | ||
415 | copies to our buffer of decoded symbols (dbuf) now. (The last | ||
416 | literal used is the one at the head of the mtfSymbol array.) */ | ||
417 | |||
418 | if(runPos) { | ||
419 | runPos=0; | ||
420 | if(dbufCount+t>=dbufSize) return RETVAL_DATA_ERROR; | ||
421 | |||
422 | uc = symToByte[mtfSymbol[0]]; | ||
423 | byteCount[uc] += t; | ||
424 | while (t--) dbuf[dbufCount++]=uc; | ||
425 | } | ||
426 | |||
427 | /* Is this the terminating symbol? */ | ||
428 | |||
429 | if(nextSym>symTotal) break; | ||
430 | |||
431 | /* At this point, nextSym indicates a new literal character. Subtract | ||
432 | one to get the position in the MTF array at which this literal is | ||
433 | currently to be found. (Note that the result can't be -1 or 0, | ||
434 | because 0 and 1 are RUNA and RUNB. But another instance of the | ||
435 | first symbol in the mtf array, position 0, would have been handled | ||
436 | as part of a run above. Therefore 1 unused mtf position minus | ||
437 | 2 non-literal nextSym values equals -1.) */ | ||
438 | |||
439 | if(dbufCount>=dbufSize) return RETVAL_DATA_ERROR; | ||
440 | i = nextSym - 1; | ||
441 | uc = mtfSymbol[i]; | ||
442 | |||
443 | /* Adjust the MTF array. Since we typically expect to move only a | ||
444 | * small number of symbols, and are bound by 256 in any case, using | ||
445 | * memmove here would typically be bigger and slower due to function | ||
446 | * call overhead and other assorted setup costs. */ | ||
447 | |||
448 | do { | ||
449 | mtfSymbol[i] = mtfSymbol[i-1]; | ||
450 | } while (--i); | ||
451 | mtfSymbol[0] = uc; | ||
452 | uc=symToByte[uc]; | ||
453 | |||
454 | /* We have our literal byte. Save it into dbuf. */ | ||
455 | |||
456 | byteCount[uc]++; | ||
457 | dbuf[dbufCount++] = (unsigned int)uc; | ||
458 | |||
459 | /* Skip group initialization if we're not done with this group. Done | ||
460 | * this way to avoid compiler warning. */ | ||
461 | |||
462 | end_of_huffman_loop: | ||
463 | if(symCount--) goto continue_this_group; | ||
464 | } | ||
465 | |||
466 | /* At this point, we've read all the Huffman-coded symbols (and repeated | ||
467 | runs) for this block from the input stream, and decoded them into the | ||
468 | intermediate buffer. There are dbufCount many decoded bytes in dbuf[]. | ||
469 | Now undo the Burrows-Wheeler transform on dbuf. | ||
470 | See http://dogma.net/markn/articles/bwt/bwt.htm | ||
471 | */ | ||
472 | |||
473 | /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */ | ||
474 | |||
475 | j=0; | ||
476 | for (i=0;i<256;i++) { | ||
477 | k=j+byteCount[i]; | ||
478 | byteCount[i] = j; | ||
479 | j=k; | ||
480 | } | ||
481 | |||
482 | /* Figure out what order dbuf would be in if we sorted it. */ | ||
483 | |||
484 | for (i=0;i<dbufCount;i++) { | ||
485 | uc=(unsigned char)(dbuf[i] & 0xff); | ||
486 | dbuf[byteCount[uc]] |= (i << 8); | ||
487 | byteCount[uc]++; | ||
488 | } | ||
489 | |||
490 | /* Decode first byte by hand to initialize "previous" byte. Note that it | ||
491 | doesn't get output, and if the first three characters are identical | ||
492 | it doesn't qualify as a run (hence writeRunCountdown=5). */ | ||
493 | |||
494 | if(dbufCount) { | ||
495 | if(origPtr>=dbufCount) return RETVAL_DATA_ERROR; | ||
496 | bd->writePos=dbuf[origPtr]; | ||
497 | bd->writeCurrent=(unsigned char)(bd->writePos&0xff); | ||
498 | bd->writePos>>=8; | ||
499 | bd->writeRunCountdown=5; | ||
500 | } | ||
501 | bd->writeCount=dbufCount; | ||
502 | |||
503 | return RETVAL_OK; | ||
504 | } | ||
505 | |||
506 | /* Undo burrows-wheeler transform on intermediate buffer to produce output. | ||
507 | If start_bunzip was initialized with out_fd=-1, then up to len bytes of | ||
508 | data are written to outbuf. Return value is number of bytes written or | ||
509 | error (all errors are negative numbers). If out_fd!=-1, outbuf and len | ||
510 | are ignored, data is written to out_fd and return is RETVAL_OK or error. | ||
511 | */ | ||
512 | |||
513 | static int read_bunzip(bunzip_data *bd, char *outbuf, int len) | ||
514 | { | ||
515 | const unsigned int *dbuf; | ||
516 | int pos,current,previous,gotcount; | ||
517 | |||
518 | /* If last read was short due to end of file, return last block now */ | ||
519 | if(bd->writeCount<0) return bd->writeCount; | ||
520 | |||
521 | gotcount = 0; | ||
522 | dbuf=bd->dbuf; | ||
523 | pos=bd->writePos; | ||
524 | current=bd->writeCurrent; | ||
525 | |||
526 | /* We will always have pending decoded data to write into the output | ||
527 | buffer unless this is the very first call (in which case we haven't | ||
528 | Huffman-decoded a block into the intermediate buffer yet). */ | ||
529 | |||
530 | if (bd->writeCopies) { | ||
531 | |||
532 | /* Inside the loop, writeCopies means extra copies (beyond 1) */ | ||
533 | |||
534 | --bd->writeCopies; | ||
535 | |||
536 | /* Loop outputting bytes */ | ||
537 | |||
538 | for (;;) { | ||
539 | |||
540 | /* If the output buffer is full, snapshot state and return */ | ||
541 | |||
542 | if(gotcount >= len) { | ||
543 | bd->writePos=pos; | ||
544 | bd->writeCurrent=current; | ||
545 | bd->writeCopies++; | ||
546 | return len; | ||
547 | } | ||
548 | |||
549 | /* Write next byte into output buffer, updating CRC */ | ||
550 | |||
551 | outbuf[gotcount++] = current; | ||
552 | bd->writeCRC=(((bd->writeCRC)<<8) | ||
553 | ^bd->crc32Table[((bd->writeCRC)>>24)^current]); | ||
554 | |||
555 | /* Loop now if we're outputting multiple copies of this byte */ | ||
556 | |||
557 | if (bd->writeCopies) { | ||
558 | --bd->writeCopies; | ||
559 | continue; | ||
560 | } | ||
561 | decode_next_byte: | ||
562 | if (!bd->writeCount--) break; | ||
563 | /* Follow sequence vector to undo Burrows-Wheeler transform */ | ||
564 | previous=current; | ||
565 | pos=dbuf[pos]; | ||
566 | current=pos&0xff; | ||
567 | pos>>=8; | ||
568 | |||
569 | /* After 3 consecutive copies of the same byte, the 4th is a repeat | ||
570 | count. We count down from 4 instead | ||
571 | * of counting up because testing for non-zero is faster */ | ||
572 | |||
573 | if(--bd->writeRunCountdown) { | ||
574 | if(current!=previous) bd->writeRunCountdown=4; | ||
575 | } else { | ||
576 | |||
577 | /* We have a repeated run, this byte indicates the count */ | ||
578 | |||
579 | bd->writeCopies=current; | ||
580 | current=previous; | ||
581 | bd->writeRunCountdown=5; | ||
582 | |||
583 | /* Sometimes there are just 3 bytes (run length 0) */ | ||
584 | |||
585 | if(!bd->writeCopies) goto decode_next_byte; | ||
586 | |||
587 | /* Subtract the 1 copy we'd output anyway to get extras */ | ||
588 | |||
589 | --bd->writeCopies; | ||
590 | } | ||
591 | } | ||
592 | |||
593 | /* Decompression of this block completed successfully */ | ||
594 | |||
595 | bd->writeCRC=~bd->writeCRC; | ||
596 | bd->totalCRC=((bd->totalCRC<<1) | (bd->totalCRC>>31)) ^ bd->writeCRC; | ||
597 | |||
598 | /* If this block had a CRC error, force file level CRC error. */ | ||
599 | |||
600 | if(bd->writeCRC!=bd->headerCRC) { | ||
601 | bd->totalCRC=bd->headerCRC+1; | ||
602 | return RETVAL_LAST_BLOCK; | ||
603 | } | ||
604 | } | ||
605 | |||
606 | /* Refill the intermediate buffer by Huffman-decoding next block of input */ | ||
607 | /* (previous is just a convenient unused temp variable here) */ | ||
608 | |||
609 | previous=get_next_block(bd); | ||
610 | if(previous) { | ||
611 | bd->writeCount=previous; | ||
612 | return (previous!=RETVAL_LAST_BLOCK) ? previous : gotcount; | ||
613 | } | ||
614 | bd->writeCRC=~0; | ||
615 | pos=bd->writePos; | ||
616 | current=bd->writeCurrent; | ||
617 | goto decode_next_byte; | ||
618 | } | ||
619 | |||
620 | /* Allocate the structure, read file header. If in_fd==-1, inbuf must contain | ||
621 | a complete bunzip file (len bytes long). If in_fd!=-1, inbuf and len are | ||
622 | ignored, and data is read from file handle into temporary buffer. */ | ||
623 | |||
624 | static int start_bunzip(bunzip_data **bdp, int in_fd, unsigned char *inbuf, | ||
625 | int len) | ||
626 | { | ||
627 | bunzip_data *bd; | ||
628 | unsigned int i; | ||
629 | const unsigned int BZh0=(((unsigned int)'B')<<24)+(((unsigned int)'Z')<<16) | ||
630 | +(((unsigned int)'h')<<8)+(unsigned int)'0'; | ||
631 | |||
632 | /* Figure out how much data to allocate */ | ||
633 | |||
634 | i=sizeof(bunzip_data); | ||
635 | if(in_fd!=-1) i+=IOBUF_SIZE; | ||
636 | |||
637 | /* Allocate bunzip_data. Most fields initialize to zero. */ | ||
638 | |||
639 | bd=*bdp=xzalloc(i); | ||
640 | |||
641 | /* Setup input buffer */ | ||
642 | |||
643 | if(-1==(bd->in_fd=in_fd)) { | ||
644 | bd->inbuf=inbuf; | ||
645 | bd->inbufCount=len; | ||
646 | } else bd->inbuf=(unsigned char *)(bd+1); | ||
647 | |||
648 | /* Init the CRC32 table (big endian) */ | ||
649 | |||
650 | bd->crc32Table = crc32_filltable(1); | ||
651 | |||
652 | /* Setup for I/O error handling via longjmp */ | ||
653 | |||
654 | i=setjmp(bd->jmpbuf); | ||
655 | if(i) return i; | ||
656 | |||
657 | /* Ensure that file starts with "BZh['1'-'9']." */ | ||
658 | |||
659 | i = get_bits(bd,32); | ||
660 | if (((unsigned int)(i-BZh0-1)) >= 9) return RETVAL_NOT_BZIP_DATA; | ||
661 | |||
662 | /* Fourth byte (ascii '1'-'9'), indicates block size in units of 100k of | ||
663 | uncompressed data. Allocate intermediate buffer for block. */ | ||
664 | |||
665 | bd->dbufSize=100000*(i-BZh0); | ||
666 | |||
667 | bd->dbuf=xmalloc(bd->dbufSize * sizeof(int)); | ||
668 | return RETVAL_OK; | ||
669 | } | ||
670 | |||
671 | /* Example usage: decompress src_fd to dst_fd. (Stops at end of bzip data, | ||
672 | not end of file.) */ | ||
673 | |||
674 | USE_DESKTOP(long long) int | ||
675 | uncompressStream(int src_fd, int dst_fd) | ||
676 | { | ||
677 | USE_DESKTOP(long long total_written = 0;) | ||
678 | char *outbuf; | ||
679 | bunzip_data *bd; | ||
680 | int i; | ||
681 | |||
682 | outbuf=xmalloc(IOBUF_SIZE); | ||
683 | i=start_bunzip(&bd,src_fd,0,0); | ||
684 | if(!i) { | ||
685 | for (;;) { | ||
686 | if((i=read_bunzip(bd,outbuf,IOBUF_SIZE)) <= 0) break; | ||
687 | if(i!=write(dst_fd,outbuf,i)) { | ||
688 | i=RETVAL_UNEXPECTED_OUTPUT_EOF; | ||
689 | break; | ||
690 | } | ||
691 | USE_DESKTOP(total_written += i;) | ||
692 | } | ||
693 | } | ||
694 | |||
695 | /* Check CRC and release memory */ | ||
696 | |||
697 | if(i==RETVAL_LAST_BLOCK) { | ||
698 | if (bd->headerCRC!=bd->totalCRC) { | ||
699 | bb_error_msg("data integrity error when decompressing"); | ||
700 | } else { | ||
701 | i=RETVAL_OK; | ||
702 | } | ||
703 | } else if (i==RETVAL_UNEXPECTED_OUTPUT_EOF) { | ||
704 | bb_error_msg("compressed file ends unexpectedly"); | ||
705 | } else { | ||
706 | bb_error_msg("decompression failed"); | ||
707 | } | ||
708 | free(bd->dbuf); | ||
709 | free(bd); | ||
710 | free(outbuf); | ||
711 | |||
712 | return i ? i : USE_DESKTOP(total_written) + 0; | ||
713 | } | ||
714 | |||
715 | #ifdef TESTING | ||
716 | |||
717 | static char * const bunzip_errors[]={NULL,"Bad file checksum","Not bzip data", | ||
718 | "Unexpected input EOF","Unexpected output EOF","Data error", | ||
719 | "Out of memory","Obsolete (pre 0.9.5) bzip format not supported."}; | ||
720 | |||
721 | /* Dumb little test thing, decompress stdin to stdout */ | ||
722 | int main(int argc, char *argv[]) | ||
723 | { | ||
724 | int i=uncompressStream(0,1); | ||
725 | char c; | ||
726 | |||
727 | if(i<0) fprintf(stderr,"%s\n", bunzip_errors[-i]); | ||
728 | else if(read(0,&c,1)) fprintf(stderr,"Trailing garbage ignored\n"); | ||
729 | return -i; | ||
730 | } | ||
731 | #endif |