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1 | /* Small bzip2 deflate implementation, by Rob Landley (rob@landley.net). | |
2 | ||
3 | Based on bzip2 decompression code by Julian R Seward (jseward@acm.org), | |
4 | which also acknowledges contributions by Mike Burrows, David Wheeler, | |
5 | Peter Fenwick, Alistair Moffat, Radford Neal, Ian H. Witten, | |
6 | Robert Sedgewick, and Jon L. Bentley. | |
7 | ||
8 | This code is licensed under the LGPLv2: | |
9 | LGPL (http://www.gnu.org/copyleft/lgpl.html | |
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 in the name of the woman I loved, who | |
26 | passed away Feb. 12, 2003. | |
27 | ||
28 | In memory of Toni W. Hagan | |
29 | ||
30 | Hospice of Acadiana, Inc. | |
31 | 2600 Johnston St., Suite 200 | |
32 | Lafayette, LA 70503-3240 | |
33 | ||
34 | Phone (337) 232-1234 or 1-800-738-2226 | |
35 | Fax (337) 232-1297 | |
36 | ||
37 | https://www.hospiceacadiana.com/ | |
38 | ||
39 | Manuel | |
40 | */ | |
41 | ||
42 | /* | |
43 | Made it fit for running in Linux Kernel by Alain Knaff (alain@knaff.lu) | |
44 | */ | |
45 | ||
46 | ||
47 | #ifdef STATIC | |
48 | #define PREBOOT | |
49 | #else | |
50 | #include <linux/decompress/bunzip2.h> | |
51 | #endif /* STATIC */ | |
52 | ||
53 | #include <linux/decompress/mm.h> | |
54 | #include <linux/crc32poly.h> | |
55 | ||
56 | #ifndef INT_MAX | |
57 | #define INT_MAX 0x7fffffff | |
58 | #endif | |
59 | ||
60 | /* Constants for Huffman coding */ | |
61 | #define MAX_GROUPS 6 | |
62 | #define GROUP_SIZE 50 /* 64 would have been more efficient */ | |
63 | #define MAX_HUFCODE_BITS 20 /* Longest Huffman code allowed */ | |
64 | #define MAX_SYMBOLS 258 /* 256 literals + RUNA + RUNB */ | |
65 | #define SYMBOL_RUNA 0 | |
66 | #define SYMBOL_RUNB 1 | |
67 | ||
68 | /* Status return values */ | |
69 | #define RETVAL_OK 0 | |
70 | #define RETVAL_LAST_BLOCK (-1) | |
71 | #define RETVAL_NOT_BZIP_DATA (-2) | |
72 | #define RETVAL_UNEXPECTED_INPUT_EOF (-3) | |
73 | #define RETVAL_UNEXPECTED_OUTPUT_EOF (-4) | |
74 | #define RETVAL_DATA_ERROR (-5) | |
75 | #define RETVAL_OUT_OF_MEMORY (-6) | |
76 | #define RETVAL_OBSOLETE_INPUT (-7) | |
77 | ||
78 | /* Other housekeeping constants */ | |
79 | #define BZIP2_IOBUF_SIZE 4096 | |
80 | ||
81 | /* This is what we know about each Huffman coding group */ | |
82 | struct group_data { | |
83 | /* We have an extra slot at the end of limit[] for a sentinal value. */ | |
84 | int limit[MAX_HUFCODE_BITS+1]; | |
85 | int base[MAX_HUFCODE_BITS]; | |
86 | int permute[MAX_SYMBOLS]; | |
87 | int minLen, maxLen; | |
88 | }; | |
89 | ||
90 | /* Structure holding all the housekeeping data, including IO buffers and | |
91 | memory that persists between calls to bunzip */ | |
92 | struct bunzip_data { | |
93 | /* State for interrupting output loop */ | |
94 | int writeCopies, writePos, writeRunCountdown, writeCount, writeCurrent; | |
95 | /* I/O tracking data (file handles, buffers, positions, etc.) */ | |
96 | long (*fill)(void*, unsigned long); | |
97 | long inbufCount, inbufPos /*, outbufPos*/; | |
98 | unsigned char *inbuf /*,*outbuf*/; | |
99 | unsigned int inbufBitCount, inbufBits; | |
100 | /* The CRC values stored in the block header and calculated from the | |
101 | data */ | |
102 | unsigned int crc32Table[256], headerCRC, totalCRC, writeCRC; | |
103 | /* Intermediate buffer and its size (in bytes) */ | |
104 | unsigned int *dbuf, dbufSize; | |
105 | /* These things are a bit too big to go on the stack */ | |
106 | unsigned char selectors[32768]; /* nSelectors = 15 bits */ | |
107 | struct group_data groups[MAX_GROUPS]; /* Huffman coding tables */ | |
108 | int io_error; /* non-zero if we have IO error */ | |
109 | int byteCount[256]; | |
110 | unsigned char symToByte[256], mtfSymbol[256]; | |
111 | }; | |
112 | ||
113 | ||
114 | /* Return the next nnn bits of input. All reads from the compressed input | |
115 | are done through this function. All reads are big endian */ | |
116 | static unsigned int INIT get_bits(struct bunzip_data *bd, char bits_wanted) | |
117 | { | |
118 | unsigned int bits = 0; | |
119 | ||
120 | /* If we need to get more data from the byte buffer, do so. | |
121 | (Loop getting one byte at a time to enforce endianness and avoid | |
122 | unaligned access.) */ | |
123 | while (bd->inbufBitCount < bits_wanted) { | |
124 | /* If we need to read more data from file into byte buffer, do | |
125 | so */ | |
126 | if (bd->inbufPos == bd->inbufCount) { | |
127 | if (bd->io_error) | |
128 | return 0; | |
129 | bd->inbufCount = bd->fill(bd->inbuf, BZIP2_IOBUF_SIZE); | |
130 | if (bd->inbufCount <= 0) { | |
131 | bd->io_error = RETVAL_UNEXPECTED_INPUT_EOF; | |
132 | return 0; | |
133 | } | |
134 | bd->inbufPos = 0; | |
135 | } | |
136 | /* Avoid 32-bit overflow (dump bit buffer to top of output) */ | |
137 | if (bd->inbufBitCount >= 24) { | |
138 | bits = bd->inbufBits&((1 << bd->inbufBitCount)-1); | |
139 | bits_wanted -= bd->inbufBitCount; | |
140 | bits <<= bits_wanted; | |
141 | bd->inbufBitCount = 0; | |
142 | } | |
143 | /* Grab next 8 bits of input from buffer. */ | |
144 | bd->inbufBits = (bd->inbufBits << 8)|bd->inbuf[bd->inbufPos++]; | |
145 | bd->inbufBitCount += 8; | |
146 | } | |
147 | /* Calculate result */ | |
148 | bd->inbufBitCount -= bits_wanted; | |
149 | bits |= (bd->inbufBits >> bd->inbufBitCount)&((1 << bits_wanted)-1); | |
150 | ||
151 | return bits; | |
152 | } | |
153 | ||
154 | /* Unpacks the next block and sets up for the inverse burrows-wheeler step. */ | |
155 | ||
156 | static int INIT get_next_block(struct bunzip_data *bd) | |
157 | { | |
158 | struct group_data *hufGroup = NULL; | |
159 | int *base = NULL; | |
160 | int *limit = NULL; | |
161 | int dbufCount, nextSym, dbufSize, groupCount, selector, | |
162 | i, j, k, t, runPos, symCount, symTotal, nSelectors, *byteCount; | |
163 | unsigned char uc, *symToByte, *mtfSymbol, *selectors; | |
164 | unsigned int *dbuf, origPtr; | |
165 | ||
166 | dbuf = bd->dbuf; | |
167 | dbufSize = bd->dbufSize; | |
168 | selectors = bd->selectors; | |
169 | byteCount = bd->byteCount; | |
170 | symToByte = bd->symToByte; | |
171 | mtfSymbol = bd->mtfSymbol; | |
172 | ||
173 | /* Read in header signature and CRC, then validate signature. | |
174 | (last block signature means CRC is for whole file, return now) */ | |
175 | i = get_bits(bd, 24); | |
176 | j = get_bits(bd, 24); | |
177 | bd->headerCRC = get_bits(bd, 32); | |
178 | if ((i == 0x177245) && (j == 0x385090)) | |
179 | return RETVAL_LAST_BLOCK; | |
180 | if ((i != 0x314159) || (j != 0x265359)) | |
181 | return RETVAL_NOT_BZIP_DATA; | |
182 | /* We can add support for blockRandomised if anybody complains. | |
183 | There was some code for this in busybox 1.0.0-pre3, but nobody ever | |
184 | noticed that it didn't actually work. */ | |
185 | if (get_bits(bd, 1)) | |
186 | return RETVAL_OBSOLETE_INPUT; | |
187 | origPtr = get_bits(bd, 24); | |
188 | if (origPtr >= dbufSize) | |
189 | return RETVAL_DATA_ERROR; | |
190 | /* mapping table: if some byte values are never used (encoding things | |
191 | like ascii text), the compression code removes the gaps to have fewer | |
192 | symbols to deal with, and writes a sparse bitfield indicating which | |
193 | values were present. We make a translation table to convert the | |
194 | symbols back to the corresponding bytes. */ | |
195 | t = get_bits(bd, 16); | |
196 | symTotal = 0; | |
197 | for (i = 0; i < 16; i++) { | |
198 | if (t&(1 << (15-i))) { | |
199 | k = get_bits(bd, 16); | |
200 | for (j = 0; j < 16; j++) | |
201 | if (k&(1 << (15-j))) | |
202 | symToByte[symTotal++] = (16*i)+j; | |
203 | } | |
204 | } | |
205 | /* How many different Huffman coding groups does this block use? */ | |
206 | groupCount = get_bits(bd, 3); | |
207 | if (groupCount < 2 || groupCount > MAX_GROUPS) | |
208 | return RETVAL_DATA_ERROR; | |
209 | /* nSelectors: Every GROUP_SIZE many symbols we select a new | |
210 | Huffman coding group. Read in the group selector list, | |
211 | which is stored as MTF encoded bit runs. (MTF = Move To | |
212 | Front, as each value is used it's moved to the start of the | |
213 | list.) */ | |
214 | nSelectors = get_bits(bd, 15); | |
215 | if (!nSelectors) | |
216 | return RETVAL_DATA_ERROR; | |
217 | for (i = 0; i < groupCount; i++) | |
218 | mtfSymbol[i] = i; | |
219 | for (i = 0; i < nSelectors; i++) { | |
220 | /* Get next value */ | |
221 | for (j = 0; get_bits(bd, 1); j++) | |
222 | if (j >= groupCount) | |
223 | return RETVAL_DATA_ERROR; | |
224 | /* Decode MTF to get the next selector */ | |
225 | uc = mtfSymbol[j]; | |
226 | for (; j; j--) | |
227 | mtfSymbol[j] = mtfSymbol[j-1]; | |
228 | mtfSymbol[0] = selectors[i] = uc; | |
229 | } | |
230 | /* Read the Huffman coding tables for each group, which code | |
231 | for symTotal literal symbols, plus two run symbols (RUNA, | |
232 | RUNB) */ | |
233 | symCount = symTotal+2; | |
234 | for (j = 0; j < groupCount; j++) { | |
235 | unsigned char length[MAX_SYMBOLS], temp[MAX_HUFCODE_BITS+1]; | |
236 | int minLen, maxLen, pp; | |
237 | /* Read Huffman code lengths for each symbol. They're | |
238 | stored in a way similar to mtf; record a starting | |
239 | value for the first symbol, and an offset from the | |
240 | previous value for everys symbol after that. | |
241 | (Subtracting 1 before the loop and then adding it | |
242 | back at the end is an optimization that makes the | |
243 | test inside the loop simpler: symbol length 0 | |
244 | becomes negative, so an unsigned inequality catches | |
245 | it.) */ | |
246 | t = get_bits(bd, 5)-1; | |
247 | for (i = 0; i < symCount; i++) { | |
248 | for (;;) { | |
249 | if (((unsigned)t) > (MAX_HUFCODE_BITS-1)) | |
250 | return RETVAL_DATA_ERROR; | |
251 | ||
252 | /* If first bit is 0, stop. Else | |
253 | second bit indicates whether to | |
254 | increment or decrement the value. | |
255 | Optimization: grab 2 bits and unget | |
256 | the second if the first was 0. */ | |
257 | ||
258 | k = get_bits(bd, 2); | |
259 | if (k < 2) { | |
260 | bd->inbufBitCount++; | |
261 | break; | |
262 | } | |
263 | /* Add one if second bit 1, else | |
264 | * subtract 1. Avoids if/else */ | |
265 | t += (((k+1)&2)-1); | |
266 | } | |
267 | /* Correct for the initial -1, to get the | |
268 | * final symbol length */ | |
269 | length[i] = t+1; | |
270 | } | |
271 | /* Find largest and smallest lengths in this group */ | |
272 | minLen = maxLen = length[0]; | |
273 | ||
274 | for (i = 1; i < symCount; i++) { | |
275 | if (length[i] > maxLen) | |
276 | maxLen = length[i]; | |
277 | else if (length[i] < minLen) | |
278 | minLen = length[i]; | |
279 | } | |
280 | ||
281 | /* Calculate permute[], base[], and limit[] tables from | |
282 | * length[]. | |
283 | * | |
284 | * permute[] is the lookup table for converting | |
285 | * Huffman coded symbols into decoded symbols. base[] | |
286 | * is the amount to subtract from the value of a | |
287 | * Huffman symbol of a given length when using | |
288 | * permute[]. | |
289 | * | |
290 | * limit[] indicates the largest numerical value a | |
291 | * symbol with a given number of bits can have. This | |
292 | * is how the Huffman codes can vary in length: each | |
293 | * code with a value > limit[length] needs another | |
294 | * bit. | |
295 | */ | |
296 | hufGroup = bd->groups+j; | |
297 | hufGroup->minLen = minLen; | |
298 | hufGroup->maxLen = maxLen; | |
299 | /* Note that minLen can't be smaller than 1, so we | |
300 | adjust the base and limit array pointers so we're | |
301 | not always wasting the first entry. We do this | |
302 | again when using them (during symbol decoding).*/ | |
303 | base = hufGroup->base-1; | |
304 | limit = hufGroup->limit-1; | |
305 | /* Calculate permute[]. Concurrently, initialize | |
306 | * temp[] and limit[]. */ | |
307 | pp = 0; | |
308 | for (i = minLen; i <= maxLen; i++) { | |
309 | temp[i] = limit[i] = 0; | |
310 | for (t = 0; t < symCount; t++) | |
311 | if (length[t] == i) | |
312 | hufGroup->permute[pp++] = t; | |
313 | } | |
314 | /* Count symbols coded for at each bit length */ | |
315 | for (i = 0; i < symCount; i++) | |
316 | temp[length[i]]++; | |
317 | /* Calculate limit[] (the largest symbol-coding value | |
318 | *at each bit length, which is (previous limit << | |
319 | *1)+symbols at this level), and base[] (number of | |
320 | *symbols to ignore at each bit length, which is limit | |
321 | *minus the cumulative count of symbols coded for | |
322 | *already). */ | |
323 | pp = t = 0; | |
324 | for (i = minLen; i < maxLen; i++) { | |
325 | pp += temp[i]; | |
326 | /* We read the largest possible symbol size | |
327 | and then unget bits after determining how | |
328 | many we need, and those extra bits could be | |
329 | set to anything. (They're noise from | |
330 | future symbols.) At each level we're | |
331 | really only interested in the first few | |
332 | bits, so here we set all the trailing | |
333 | to-be-ignored bits to 1 so they don't | |
334 | affect the value > limit[length] | |
335 | comparison. */ | |
336 | limit[i] = (pp << (maxLen - i)) - 1; | |
337 | pp <<= 1; | |
338 | base[i+1] = pp-(t += temp[i]); | |
339 | } | |
340 | limit[maxLen+1] = INT_MAX; /* Sentinal value for | |
341 | * reading next sym. */ | |
342 | limit[maxLen] = pp+temp[maxLen]-1; | |
343 | base[minLen] = 0; | |
344 | } | |
345 | /* We've finished reading and digesting the block header. Now | |
346 | read this block's Huffman coded symbols from the file and | |
347 | undo the Huffman coding and run length encoding, saving the | |
348 | result into dbuf[dbufCount++] = uc */ | |
349 | ||
350 | /* Initialize symbol occurrence counters and symbol Move To | |
351 | * Front table */ | |
352 | for (i = 0; i < 256; i++) { | |
353 | byteCount[i] = 0; | |
354 | mtfSymbol[i] = (unsigned char)i; | |
355 | } | |
356 | /* Loop through compressed symbols. */ | |
357 | runPos = dbufCount = symCount = selector = 0; | |
358 | for (;;) { | |
359 | /* Determine which Huffman coding group to use. */ | |
360 | if (!(symCount--)) { | |
361 | symCount = GROUP_SIZE-1; | |
362 | if (selector >= nSelectors) | |
363 | return RETVAL_DATA_ERROR; | |
364 | hufGroup = bd->groups+selectors[selector++]; | |
365 | base = hufGroup->base-1; | |
366 | limit = hufGroup->limit-1; | |
367 | } | |
368 | /* Read next Huffman-coded symbol. */ | |
369 | /* Note: It is far cheaper to read maxLen bits and | |
370 | back up than it is to read minLen bits and then an | |
371 | additional bit at a time, testing as we go. | |
372 | Because there is a trailing last block (with file | |
373 | CRC), there is no danger of the overread causing an | |
374 | unexpected EOF for a valid compressed file. As a | |
375 | further optimization, we do the read inline | |
376 | (falling back to a call to get_bits if the buffer | |
377 | runs dry). The following (up to got_huff_bits:) is | |
378 | equivalent to j = get_bits(bd, hufGroup->maxLen); | |
379 | */ | |
380 | while (bd->inbufBitCount < hufGroup->maxLen) { | |
381 | if (bd->inbufPos == bd->inbufCount) { | |
382 | j = get_bits(bd, hufGroup->maxLen); | |
383 | goto got_huff_bits; | |
384 | } | |
385 | bd->inbufBits = | |
386 | (bd->inbufBits << 8)|bd->inbuf[bd->inbufPos++]; | |
387 | bd->inbufBitCount += 8; | |
388 | }; | |
389 | bd->inbufBitCount -= hufGroup->maxLen; | |
390 | j = (bd->inbufBits >> bd->inbufBitCount)& | |
391 | ((1 << hufGroup->maxLen)-1); | |
392 | got_huff_bits: | |
393 | /* Figure how many bits are in next symbol and | |
394 | * unget extras */ | |
395 | i = hufGroup->minLen; | |
396 | while (j > limit[i]) | |
397 | ++i; | |
398 | bd->inbufBitCount += (hufGroup->maxLen - i); | |
399 | /* Huffman decode value to get nextSym (with bounds checking) */ | |
400 | if ((i > hufGroup->maxLen) | |
401 | || (((unsigned)(j = (j>>(hufGroup->maxLen-i))-base[i])) | |
402 | >= MAX_SYMBOLS)) | |
403 | return RETVAL_DATA_ERROR; | |
404 | nextSym = hufGroup->permute[j]; | |
405 | /* We have now decoded the symbol, which indicates | |
406 | either a new literal byte, or a repeated run of the | |
407 | most recent literal byte. First, check if nextSym | |
408 | indicates a repeated run, and if so loop collecting | |
409 | how many times to repeat the last literal. */ | |
410 | if (((unsigned)nextSym) <= SYMBOL_RUNB) { /* RUNA or RUNB */ | |
411 | /* If this is the start of a new run, zero out | |
412 | * counter */ | |
413 | if (!runPos) { | |
414 | runPos = 1; | |
415 | t = 0; | |
416 | } | |
417 | /* Neat trick that saves 1 symbol: instead of | |
418 | or-ing 0 or 1 at each bit position, add 1 | |
419 | or 2 instead. For example, 1011 is 1 << 0 | |
420 | + 1 << 1 + 2 << 2. 1010 is 2 << 0 + 2 << 1 | |
421 | + 1 << 2. You can make any bit pattern | |
422 | that way using 1 less symbol than the basic | |
423 | or 0/1 method (except all bits 0, which | |
424 | would use no symbols, but a run of length 0 | |
425 | doesn't mean anything in this context). | |
426 | Thus space is saved. */ | |
427 | t += (runPos << nextSym); | |
428 | /* +runPos if RUNA; +2*runPos if RUNB */ | |
429 | ||
430 | runPos <<= 1; | |
431 | continue; | |
432 | } | |
433 | /* When we hit the first non-run symbol after a run, | |
434 | we now know how many times to repeat the last | |
435 | literal, so append that many copies to our buffer | |
436 | of decoded symbols (dbuf) now. (The last literal | |
437 | used is the one at the head of the mtfSymbol | |
438 | array.) */ | |
439 | if (runPos) { | |
440 | runPos = 0; | |
441 | if (dbufCount+t >= dbufSize) | |
442 | return RETVAL_DATA_ERROR; | |
443 | ||
444 | uc = symToByte[mtfSymbol[0]]; | |
445 | byteCount[uc] += t; | |
446 | while (t--) | |
447 | dbuf[dbufCount++] = uc; | |
448 | } | |
449 | /* Is this the terminating symbol? */ | |
450 | if (nextSym > symTotal) | |
451 | break; | |
452 | /* At this point, nextSym indicates a new literal | |
453 | character. Subtract one to get the position in the | |
454 | MTF array at which this literal is currently to be | |
455 | found. (Note that the result can't be -1 or 0, | |
456 | because 0 and 1 are RUNA and RUNB. But another | |
457 | instance of the first symbol in the mtf array, | |
458 | position 0, would have been handled as part of a | |
459 | run above. Therefore 1 unused mtf position minus 2 | |
460 | non-literal nextSym values equals -1.) */ | |
461 | if (dbufCount >= dbufSize) | |
462 | return RETVAL_DATA_ERROR; | |
463 | i = nextSym - 1; | |
464 | uc = mtfSymbol[i]; | |
465 | /* Adjust the MTF array. Since we typically expect to | |
466 | *move only a small number of symbols, and are bound | |
467 | *by 256 in any case, using memmove here would | |
468 | *typically be bigger and slower due to function call | |
469 | *overhead and other assorted setup costs. */ | |
470 | do { | |
471 | mtfSymbol[i] = mtfSymbol[i-1]; | |
472 | } while (--i); | |
473 | mtfSymbol[0] = uc; | |
474 | uc = symToByte[uc]; | |
475 | /* We have our literal byte. Save it into dbuf. */ | |
476 | byteCount[uc]++; | |
477 | dbuf[dbufCount++] = (unsigned int)uc; | |
478 | } | |
479 | /* At this point, we've read all the Huffman-coded symbols | |
480 | (and repeated runs) for this block from the input stream, | |
481 | and decoded them into the intermediate buffer. There are | |
482 | dbufCount many decoded bytes in dbuf[]. Now undo the | |
483 | Burrows-Wheeler transform on dbuf. See | |
484 | http://dogma.net/markn/articles/bwt/bwt.htm | |
485 | */ | |
486 | /* Turn byteCount into cumulative occurrence counts of 0 to n-1. */ | |
487 | j = 0; | |
488 | for (i = 0; i < 256; i++) { | |
489 | k = j+byteCount[i]; | |
490 | byteCount[i] = j; | |
491 | j = k; | |
492 | } | |
493 | /* Figure out what order dbuf would be in if we sorted it. */ | |
494 | for (i = 0; i < dbufCount; i++) { | |
495 | uc = (unsigned char)(dbuf[i] & 0xff); | |
496 | dbuf[byteCount[uc]] |= (i << 8); | |
497 | byteCount[uc]++; | |
498 | } | |
499 | /* Decode first byte by hand to initialize "previous" byte. | |
500 | Note that it doesn't get output, and if the first three | |
501 | characters are identical it doesn't qualify as a run (hence | |
502 | writeRunCountdown = 5). */ | |
503 | if (dbufCount) { | |
504 | if (origPtr >= dbufCount) | |
505 | return RETVAL_DATA_ERROR; | |
506 | bd->writePos = dbuf[origPtr]; | |
507 | bd->writeCurrent = (unsigned char)(bd->writePos&0xff); | |
508 | bd->writePos >>= 8; | |
509 | bd->writeRunCountdown = 5; | |
510 | } | |
511 | bd->writeCount = dbufCount; | |
512 | ||
513 | return RETVAL_OK; | |
514 | } | |
515 | ||
516 | /* Undo burrows-wheeler transform on intermediate buffer to produce output. | |
517 | If start_bunzip was initialized with out_fd =-1, then up to len bytes of | |
518 | data are written to outbuf. Return value is number of bytes written or | |
519 | error (all errors are negative numbers). If out_fd!=-1, outbuf and len | |
520 | are ignored, data is written to out_fd and return is RETVAL_OK or error. | |
521 | */ | |
522 | ||
523 | static int INIT read_bunzip(struct bunzip_data *bd, char *outbuf, int len) | |
524 | { | |
525 | const unsigned int *dbuf; | |
526 | int pos, xcurrent, previous, gotcount; | |
527 | ||
528 | /* If last read was short due to end of file, return last block now */ | |
529 | if (bd->writeCount < 0) | |
530 | return bd->writeCount; | |
531 | ||
532 | gotcount = 0; | |
533 | dbuf = bd->dbuf; | |
534 | pos = bd->writePos; | |
535 | xcurrent = bd->writeCurrent; | |
536 | ||
537 | /* We will always have pending decoded data to write into the output | |
538 | buffer unless this is the very first call (in which case we haven't | |
539 | Huffman-decoded a block into the intermediate buffer yet). */ | |
540 | ||
541 | if (bd->writeCopies) { | |
542 | /* Inside the loop, writeCopies means extra copies (beyond 1) */ | |
543 | --bd->writeCopies; | |
544 | /* Loop outputting bytes */ | |
545 | for (;;) { | |
546 | /* If the output buffer is full, snapshot | |
547 | * state and return */ | |
548 | if (gotcount >= len) { | |
549 | bd->writePos = pos; | |
550 | bd->writeCurrent = xcurrent; | |
551 | bd->writeCopies++; | |
552 | return len; | |
553 | } | |
554 | /* Write next byte into output buffer, updating CRC */ | |
555 | outbuf[gotcount++] = xcurrent; | |
556 | bd->writeCRC = (((bd->writeCRC) << 8) | |
557 | ^bd->crc32Table[((bd->writeCRC) >> 24) | |
558 | ^xcurrent]); | |
559 | /* Loop now if we're outputting multiple | |
560 | * copies of this byte */ | |
561 | if (bd->writeCopies) { | |
562 | --bd->writeCopies; | |
563 | continue; | |
564 | } | |
565 | decode_next_byte: | |
566 | if (!bd->writeCount--) | |
567 | break; | |
568 | /* Follow sequence vector to undo | |
569 | * Burrows-Wheeler transform */ | |
570 | previous = xcurrent; | |
571 | pos = dbuf[pos]; | |
572 | xcurrent = pos&0xff; | |
573 | pos >>= 8; | |
574 | /* After 3 consecutive copies of the same | |
575 | byte, the 4th is a repeat count. We count | |
576 | down from 4 instead *of counting up because | |
577 | testing for non-zero is faster */ | |
578 | if (--bd->writeRunCountdown) { | |
579 | if (xcurrent != previous) | |
580 | bd->writeRunCountdown = 4; | |
581 | } else { | |
582 | /* We have a repeated run, this byte | |
583 | * indicates the count */ | |
584 | bd->writeCopies = xcurrent; | |
585 | xcurrent = previous; | |
586 | bd->writeRunCountdown = 5; | |
587 | /* Sometimes there are just 3 bytes | |
588 | * (run length 0) */ | |
589 | if (!bd->writeCopies) | |
590 | goto decode_next_byte; | |
591 | /* Subtract the 1 copy we'd output | |
592 | * anyway to get extras */ | |
593 | --bd->writeCopies; | |
594 | } | |
595 | } | |
596 | /* Decompression of this block completed successfully */ | |
597 | bd->writeCRC = ~bd->writeCRC; | |
598 | bd->totalCRC = ((bd->totalCRC << 1) | | |
599 | (bd->totalCRC >> 31)) ^ bd->writeCRC; | |
600 | /* If this block had a CRC error, force file level CRC error. */ | |
601 | if (bd->writeCRC != bd->headerCRC) { | |
602 | bd->totalCRC = bd->headerCRC+1; | |
603 | return RETVAL_LAST_BLOCK; | |
604 | } | |
605 | } | |
606 | ||
607 | /* Refill the intermediate buffer by Huffman-decoding next | |
608 | * block of input */ | |
609 | /* (previous is just a convenient unused temp variable here) */ | |
610 | previous = get_next_block(bd); | |
611 | if (previous) { | |
612 | bd->writeCount = previous; | |
613 | return (previous != RETVAL_LAST_BLOCK) ? previous : gotcount; | |
614 | } | |
615 | bd->writeCRC = 0xffffffffUL; | |
616 | pos = bd->writePos; | |
617 | xcurrent = bd->writeCurrent; | |
618 | goto decode_next_byte; | |
619 | } | |
620 | ||
621 | static long INIT nofill(void *buf, unsigned long len) | |
622 | { | |
623 | return -1; | |
624 | } | |
625 | ||
626 | /* Allocate the structure, read file header. If in_fd ==-1, inbuf must contain | |
627 | a complete bunzip file (len bytes long). If in_fd!=-1, inbuf and len are | |
628 | ignored, and data is read from file handle into temporary buffer. */ | |
629 | static int INIT start_bunzip(struct bunzip_data **bdp, void *inbuf, long len, | |
630 | long (*fill)(void*, unsigned long)) | |
631 | { | |
632 | struct bunzip_data *bd; | |
633 | unsigned int i, j, c; | |
634 | const unsigned int BZh0 = | |
635 | (((unsigned int)'B') << 24)+(((unsigned int)'Z') << 16) | |
636 | +(((unsigned int)'h') << 8)+(unsigned int)'0'; | |
637 | ||
638 | /* Figure out how much data to allocate */ | |
639 | i = sizeof(struct bunzip_data); | |
640 | ||
641 | /* Allocate bunzip_data. Most fields initialize to zero. */ | |
642 | bd = *bdp = malloc(i); | |
643 | if (!bd) | |
644 | return RETVAL_OUT_OF_MEMORY; | |
645 | memset(bd, 0, sizeof(struct bunzip_data)); | |
646 | /* Setup input buffer */ | |
647 | bd->inbuf = inbuf; | |
648 | bd->inbufCount = len; | |
649 | if (fill != NULL) | |
650 | bd->fill = fill; | |
651 | else | |
652 | bd->fill = nofill; | |
653 | ||
654 | /* Init the CRC32 table (big endian) */ | |
655 | for (i = 0; i < 256; i++) { | |
656 | c = i << 24; | |
657 | for (j = 8; j; j--) | |
658 | c = c&0x80000000 ? (c << 1)^(CRC32_POLY_BE) : (c << 1); | |
659 | bd->crc32Table[i] = c; | |
660 | } | |
661 | ||
662 | /* Ensure that file starts with "BZh['1'-'9']." */ | |
663 | i = get_bits(bd, 32); | |
664 | if (((unsigned int)(i-BZh0-1)) >= 9) | |
665 | return RETVAL_NOT_BZIP_DATA; | |
666 | ||
667 | /* Fourth byte (ascii '1'-'9'), indicates block size in units of 100k of | |
668 | uncompressed data. Allocate intermediate buffer for block. */ | |
669 | bd->dbufSize = 100000*(i-BZh0); | |
670 | ||
671 | bd->dbuf = large_malloc(bd->dbufSize * sizeof(int)); | |
672 | if (!bd->dbuf) | |
673 | return RETVAL_OUT_OF_MEMORY; | |
674 | return RETVAL_OK; | |
675 | } | |
676 | ||
677 | /* Example usage: decompress src_fd to dst_fd. (Stops at end of bzip2 data, | |
678 | not end of file.) */ | |
679 | STATIC int INIT bunzip2(unsigned char *buf, long len, | |
680 | long (*fill)(void*, unsigned long), | |
681 | long (*flush)(void*, unsigned long), | |
682 | unsigned char *outbuf, | |
683 | long *pos, | |
684 | void(*error)(char *x)) | |
685 | { | |
686 | struct bunzip_data *bd; | |
687 | int i = -1; | |
688 | unsigned char *inbuf; | |
689 | ||
690 | if (flush) | |
691 | outbuf = malloc(BZIP2_IOBUF_SIZE); | |
692 | ||
693 | if (!outbuf) { | |
694 | error("Could not allocate output buffer"); | |
695 | return RETVAL_OUT_OF_MEMORY; | |
696 | } | |
697 | if (buf) | |
698 | inbuf = buf; | |
699 | else | |
700 | inbuf = malloc(BZIP2_IOBUF_SIZE); | |
701 | if (!inbuf) { | |
702 | error("Could not allocate input buffer"); | |
703 | i = RETVAL_OUT_OF_MEMORY; | |
704 | goto exit_0; | |
705 | } | |
706 | i = start_bunzip(&bd, inbuf, len, fill); | |
707 | if (!i) { | |
708 | for (;;) { | |
709 | i = read_bunzip(bd, outbuf, BZIP2_IOBUF_SIZE); | |
710 | if (i <= 0) | |
711 | break; | |
712 | if (!flush) | |
713 | outbuf += i; | |
714 | else | |
715 | if (i != flush(outbuf, i)) { | |
716 | i = RETVAL_UNEXPECTED_OUTPUT_EOF; | |
717 | break; | |
718 | } | |
719 | } | |
720 | } | |
721 | /* Check CRC and release memory */ | |
722 | if (i == RETVAL_LAST_BLOCK) { | |
723 | if (bd->headerCRC != bd->totalCRC) | |
724 | error("Data integrity error when decompressing."); | |
725 | else | |
726 | i = RETVAL_OK; | |
727 | } else if (i == RETVAL_UNEXPECTED_OUTPUT_EOF) { | |
728 | error("Compressed file ends unexpectedly"); | |
729 | } | |
730 | if (!bd) | |
731 | goto exit_1; | |
732 | if (bd->dbuf) | |
733 | large_free(bd->dbuf); | |
734 | if (pos) | |
735 | *pos = bd->inbufPos; | |
736 | free(bd); | |
737 | exit_1: | |
738 | if (!buf) | |
739 | free(inbuf); | |
740 | exit_0: | |
741 | if (flush) | |
742 | free(outbuf); | |
743 | return i; | |
744 | } | |
745 | ||
746 | #ifdef PREBOOT | |
747 | STATIC int INIT __decompress(unsigned char *buf, long len, | |
748 | long (*fill)(void*, unsigned long), | |
749 | long (*flush)(void*, unsigned long), | |
750 | unsigned char *outbuf, long olen, | |
751 | long *pos, | |
752 | void (*error)(char *x)) | |
753 | { | |
754 | return bunzip2(buf, len - 4, fill, flush, outbuf, pos, error); | |
755 | } | |
756 | #endif |