Branch data Line data Source code
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 : : http://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 : 0 : 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 : 0 : while (bd->inbufBitCount < bits_wanted) {
124 : : /* If we need to read more data from file into byte buffer, do
125 : : so */
126 : 0 : if (bd->inbufPos == bd->inbufCount) {
127 : 0 : if (bd->io_error)
128 : : return 0;
129 : 0 : bd->inbufCount = bd->fill(bd->inbuf, BZIP2_IOBUF_SIZE);
130 : 0 : if (bd->inbufCount <= 0) {
131 : 0 : bd->io_error = RETVAL_UNEXPECTED_INPUT_EOF;
132 : 0 : return 0;
133 : : }
134 : 0 : bd->inbufPos = 0;
135 : : }
136 : : /* Avoid 32-bit overflow (dump bit buffer to top of output) */
137 : 0 : if (bd->inbufBitCount >= 24) {
138 : 0 : bits = bd->inbufBits&((1 << bd->inbufBitCount)-1);
139 : 0 : bits_wanted -= bd->inbufBitCount;
140 : 0 : bits <<= bits_wanted;
141 : 0 : bd->inbufBitCount = 0;
142 : : }
143 : : /* Grab next 8 bits of input from buffer. */
144 : 0 : bd->inbufBits = (bd->inbufBits << 8)|bd->inbuf[bd->inbufPos++];
145 : 0 : bd->inbufBitCount += 8;
146 : : }
147 : : /* Calculate result */
148 : 0 : bd->inbufBitCount -= bits_wanted;
149 : 0 : bits |= (bd->inbufBits >> bd->inbufBitCount)&((1 << bits_wanted)-1);
150 : :
151 : 0 : return bits;
152 : : }
153 : :
154 : : /* Unpacks the next block and sets up for the inverse burrows-wheeler step. */
155 : :
156 : 0 : 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 : 0 : dbuf = bd->dbuf;
167 : 0 : dbufSize = bd->dbufSize;
168 : 0 : selectors = bd->selectors;
169 : 0 : byteCount = bd->byteCount;
170 : 0 : symToByte = bd->symToByte;
171 : 0 : 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 : 0 : i = get_bits(bd, 24);
176 : 0 : j = get_bits(bd, 24);
177 : 0 : bd->headerCRC = get_bits(bd, 32);
178 : 0 : if ((i == 0x177245) && (j == 0x385090))
179 : : return RETVAL_LAST_BLOCK;
180 : 0 : 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 : 0 : if (get_bits(bd, 1))
186 : : return RETVAL_OBSOLETE_INPUT;
187 : 0 : origPtr = get_bits(bd, 24);
188 : 0 : 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 : 0 : t = get_bits(bd, 16);
196 : : symTotal = 0;
197 : 0 : for (i = 0; i < 16; i++) {
198 : 0 : if (t&(1 << (15-i))) {
199 : 0 : k = get_bits(bd, 16);
200 : 0 : for (j = 0; j < 16; j++)
201 : 0 : if (k&(1 << (15-j)))
202 : 0 : symToByte[symTotal++] = (16*i)+j;
203 : : }
204 : : }
205 : : /* How many different Huffman coding groups does this block use? */
206 : 0 : groupCount = get_bits(bd, 3);
207 : 0 : 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 : 0 : nSelectors = get_bits(bd, 15);
215 : 0 : if (!nSelectors)
216 : : return RETVAL_DATA_ERROR;
217 : 0 : for (i = 0; i < groupCount; i++)
218 : 0 : mtfSymbol[i] = i;
219 : 0 : for (i = 0; i < nSelectors; i++) {
220 : : /* Get next value */
221 : 0 : for (j = 0; get_bits(bd, 1); j++)
222 : 0 : if (j >= groupCount)
223 : : return RETVAL_DATA_ERROR;
224 : : /* Decode MTF to get the next selector */
225 : 0 : uc = mtfSymbol[j];
226 : 0 : for (; j; j--)
227 : 0 : mtfSymbol[j] = mtfSymbol[j-1];
228 : 0 : 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 : 0 : symCount = symTotal+2;
234 : 0 : 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 : 0 : t = get_bits(bd, 5)-1;
247 : 0 : for (i = 0; i < symCount; i++) {
248 : : for (;;) {
249 : 0 : if (((unsigned)t) > (MAX_HUFCODE_BITS-1))
250 : 0 : 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 : 0 : k = get_bits(bd, 2);
259 : 0 : if (k < 2) {
260 : 0 : bd->inbufBitCount++;
261 : : break;
262 : : }
263 : : /* Add one if second bit 1, else
264 : : * subtract 1. Avoids if/else */
265 : 0 : t += (((k+1)&2)-1);
266 : 0 : }
267 : : /* Correct for the initial -1, to get the
268 : : * final symbol length */
269 : 0 : length[i] = t+1;
270 : : }
271 : : /* Find largest and smallest lengths in this group */
272 : 0 : minLen = maxLen = length[0];
273 : :
274 : 0 : for (i = 1; i < symCount; i++) {
275 : 0 : if (length[i] > maxLen)
276 : : maxLen = length[i];
277 : 0 : 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 : 0 : hufGroup = bd->groups+j;
297 : 0 : hufGroup->minLen = minLen;
298 : 0 : 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 : 0 : base = hufGroup->base-1;
304 : 0 : limit = hufGroup->limit-1;
305 : : /* Calculate permute[]. Concurrently, initialize
306 : : * temp[] and limit[]. */
307 : : pp = 0;
308 : 0 : for (i = minLen; i <= maxLen; i++) {
309 : 0 : temp[i] = limit[i] = 0;
310 : 0 : for (t = 0; t < symCount; t++)
311 : 0 : if (length[t] == i)
312 : 0 : hufGroup->permute[pp++] = t;
313 : : }
314 : : /* Count symbols coded for at each bit length */
315 : 0 : for (i = 0; i < symCount; i++)
316 : 0 : 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 : 0 : for (i = minLen; i < maxLen; i++) {
325 : 0 : 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 : 0 : limit[i] = (pp << (maxLen - i)) - 1;
337 : 0 : pp <<= 1;
338 : 0 : base[i+1] = pp-(t += temp[i]);
339 : : }
340 : 0 : limit[maxLen+1] = INT_MAX; /* Sentinal value for
341 : : * reading next sym. */
342 : 0 : limit[maxLen] = pp+temp[maxLen]-1;
343 : 0 : 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 : 0 : for (i = 0; i < 256; i++) {
353 : 0 : byteCount[i] = 0;
354 : 0 : 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 : 0 : if (!(symCount--)) {
361 : : symCount = GROUP_SIZE-1;
362 : 0 : if (selector >= nSelectors)
363 : : return RETVAL_DATA_ERROR;
364 : 0 : hufGroup = bd->groups+selectors[selector++];
365 : 0 : base = hufGroup->base-1;
366 : 0 : 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 : 0 : while (bd->inbufBitCount < hufGroup->maxLen) {
381 : 0 : if (bd->inbufPos == bd->inbufCount) {
382 : 0 : j = get_bits(bd, hufGroup->maxLen);
383 : 0 : goto got_huff_bits;
384 : : }
385 : 0 : bd->inbufBits =
386 : 0 : (bd->inbufBits << 8)|bd->inbuf[bd->inbufPos++];
387 : 0 : bd->inbufBitCount += 8;
388 : : };
389 : 0 : bd->inbufBitCount -= hufGroup->maxLen;
390 : 0 : j = (bd->inbufBits >> bd->inbufBitCount)&
391 : 0 : ((1 << hufGroup->maxLen)-1);
392 : : got_huff_bits:
393 : : /* Figure how how many bits are in next symbol and
394 : : * unget extras */
395 : 0 : i = hufGroup->minLen;
396 : 0 : while (j > limit[i])
397 : 0 : ++i;
398 : 0 : bd->inbufBitCount += (hufGroup->maxLen - i);
399 : : /* Huffman decode value to get nextSym (with bounds checking) */
400 : 0 : if ((i > hufGroup->maxLen)
401 : 0 : || (((unsigned)(j = (j>>(hufGroup->maxLen-i))-base[i]))
402 : : >= MAX_SYMBOLS))
403 : : return RETVAL_DATA_ERROR;
404 : 0 : 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 : 0 : if (((unsigned)nextSym) <= SYMBOL_RUNB) { /* RUNA or RUNB */
411 : : /* If this is the start of a new run, zero out
412 : : * counter */
413 : 0 : 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 : 0 : t += (runPos << nextSym);
428 : : /* +runPos if RUNA; +2*runPos if RUNB */
429 : :
430 : 0 : runPos <<= 1;
431 : 0 : 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 : 0 : if (runPos) {
440 : : runPos = 0;
441 : 0 : if (dbufCount+t >= dbufSize)
442 : : return RETVAL_DATA_ERROR;
443 : :
444 : 0 : uc = symToByte[mtfSymbol[0]];
445 : 0 : byteCount[uc] += t;
446 : 0 : while (t--)
447 : 0 : dbuf[dbufCount++] = uc;
448 : : }
449 : : /* Is this the terminating symbol? */
450 : 0 : 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 : 0 : if (dbufCount >= dbufSize)
462 : : return RETVAL_DATA_ERROR;
463 : 0 : i = nextSym - 1;
464 : 0 : 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 : 0 : mtfSymbol[i] = mtfSymbol[i-1];
472 : 0 : } while (--i);
473 : 0 : mtfSymbol[0] = uc;
474 : 0 : uc = symToByte[uc];
475 : : /* We have our literal byte. Save it into dbuf. */
476 : 0 : byteCount[uc]++;
477 : 0 : 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 : 0 : for (i = 0; i < 256; i++) {
489 : 0 : k = j+byteCount[i];
490 : 0 : byteCount[i] = j;
491 : : j = k;
492 : : }
493 : : /* Figure out what order dbuf would be in if we sorted it. */
494 : 0 : for (i = 0; i < dbufCount; i++) {
495 : 0 : uc = (unsigned char)(dbuf[i] & 0xff);
496 : 0 : dbuf[byteCount[uc]] |= (i << 8);
497 : 0 : 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 : 0 : if (dbufCount) {
504 : 0 : if (origPtr >= dbufCount)
505 : : return RETVAL_DATA_ERROR;
506 : 0 : bd->writePos = dbuf[origPtr];
507 : 0 : bd->writeCurrent = (unsigned char)(bd->writePos&0xff);
508 : 0 : bd->writePos >>= 8;
509 : 0 : bd->writeRunCountdown = 5;
510 : : }
511 : 0 : bd->writeCount = dbufCount;
512 : :
513 : 0 : 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 : 0 : 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 : 0 : if (bd->writeCount < 0)
530 : : return bd->writeCount;
531 : :
532 : : gotcount = 0;
533 : 0 : dbuf = bd->dbuf;
534 : 0 : pos = bd->writePos;
535 : 0 : 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 : 0 : if (bd->writeCopies) {
542 : : /* Inside the loop, writeCopies means extra copies (beyond 1) */
543 : 0 : --bd->writeCopies;
544 : : /* Loop outputting bytes */
545 : : for (;;) {
546 : : /* If the output buffer is full, snapshot
547 : : * state and return */
548 : 0 : if (gotcount >= len) {
549 : 0 : bd->writePos = pos;
550 : 0 : bd->writeCurrent = xcurrent;
551 : 0 : bd->writeCopies++;
552 : 0 : return len;
553 : : }
554 : : /* Write next byte into output buffer, updating CRC */
555 : 0 : outbuf[gotcount++] = xcurrent;
556 : 0 : bd->writeCRC = (((bd->writeCRC) << 8)
557 : 0 : ^bd->crc32Table[((bd->writeCRC) >> 24)
558 : 0 : ^xcurrent]);
559 : : /* Loop now if we're outputting multiple
560 : : * copies of this byte */
561 : 0 : if (bd->writeCopies) {
562 : 0 : --bd->writeCopies;
563 : 0 : continue;
564 : : }
565 : : decode_next_byte:
566 : 0 : if (!bd->writeCount--)
567 : : break;
568 : : /* Follow sequence vector to undo
569 : : * Burrows-Wheeler transform */
570 : : previous = xcurrent;
571 : 0 : pos = dbuf[pos];
572 : 0 : xcurrent = pos&0xff;
573 : 0 : 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 : 0 : if (--bd->writeRunCountdown) {
579 : 0 : if (xcurrent != previous)
580 : 0 : bd->writeRunCountdown = 4;
581 : : } else {
582 : : /* We have a repeated run, this byte
583 : : * indicates the count */
584 : 0 : bd->writeCopies = xcurrent;
585 : : xcurrent = previous;
586 : 0 : bd->writeRunCountdown = 5;
587 : : /* Sometimes there are just 3 bytes
588 : : * (run length 0) */
589 : 0 : if (!bd->writeCopies)
590 : : goto decode_next_byte;
591 : : /* Subtract the 1 copy we'd output
592 : : * anyway to get extras */
593 : 0 : --bd->writeCopies;
594 : : }
595 : : }
596 : : /* Decompression of this block completed successfully */
597 : 0 : bd->writeCRC = ~bd->writeCRC;
598 : 0 : bd->totalCRC = ((bd->totalCRC << 1) |
599 : 0 : (bd->totalCRC >> 31)) ^ bd->writeCRC;
600 : : /* If this block had a CRC error, force file level CRC error. */
601 : 0 : if (bd->writeCRC != bd->headerCRC) {
602 : 0 : bd->totalCRC = bd->headerCRC+1;
603 : 0 : 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 : 0 : previous = get_next_block(bd);
611 : 0 : if (previous) {
612 : 0 : bd->writeCount = previous;
613 : 0 : return (previous != RETVAL_LAST_BLOCK) ? previous : gotcount;
614 : : }
615 : 0 : bd->writeCRC = 0xffffffffUL;
616 : 0 : pos = bd->writePos;
617 : 0 : xcurrent = bd->writeCurrent;
618 : 0 : goto decode_next_byte;
619 : : }
620 : :
621 : 0 : static long INIT nofill(void *buf, unsigned long len)
622 : : {
623 : 0 : 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 : 0 : 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 : 0 : bd = *bdp = malloc(i);
643 : 0 : if (!bd)
644 : : return RETVAL_OUT_OF_MEMORY;
645 : 0 : memset(bd, 0, sizeof(struct bunzip_data));
646 : : /* Setup input buffer */
647 : 0 : bd->inbuf = inbuf;
648 : 0 : bd->inbufCount = len;
649 : 0 : if (fill != NULL)
650 : 0 : bd->fill = fill;
651 : : else
652 : 0 : bd->fill = nofill;
653 : :
654 : : /* Init the CRC32 table (big endian) */
655 : 0 : for (i = 0; i < 256; i++) {
656 : 0 : c = i << 24;
657 : 0 : for (j = 8; j; j--)
658 : 0 : c = c&0x80000000 ? (c << 1)^(CRC32_POLY_BE) : (c << 1);
659 : 0 : bd->crc32Table[i] = c;
660 : : }
661 : :
662 : : /* Ensure that file starts with "BZh['1'-'9']." */
663 : 0 : i = get_bits(bd, 32);
664 : 0 : 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 : 0 : bd->dbufSize = 100000*(i-BZh0);
670 : :
671 : 0 : bd->dbuf = large_malloc(bd->dbufSize * sizeof(int));
672 : 0 : if (!bd->dbuf)
673 : : return RETVAL_OUT_OF_MEMORY;
674 : 0 : 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 : 0 : 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 : 0 : if (flush)
691 : : outbuf = malloc(BZIP2_IOBUF_SIZE);
692 : :
693 : 0 : if (!outbuf) {
694 : 0 : error("Could not allocate output buffer");
695 : 0 : return RETVAL_OUT_OF_MEMORY;
696 : : }
697 : 0 : if (buf)
698 : : inbuf = buf;
699 : : else
700 : : inbuf = malloc(BZIP2_IOBUF_SIZE);
701 : 0 : if (!inbuf) {
702 : 0 : error("Could not allocate input buffer");
703 : : i = RETVAL_OUT_OF_MEMORY;
704 : 0 : goto exit_0;
705 : : }
706 : 0 : i = start_bunzip(&bd, inbuf, len, fill);
707 : 0 : if (!i) {
708 : : for (;;) {
709 : 0 : i = read_bunzip(bd, outbuf, BZIP2_IOBUF_SIZE);
710 : 0 : if (i <= 0)
711 : : break;
712 : 0 : if (!flush)
713 : 0 : outbuf += i;
714 : : else
715 : 0 : if (i != flush(outbuf, i)) {
716 : : i = RETVAL_UNEXPECTED_OUTPUT_EOF;
717 : : break;
718 : : }
719 : : }
720 : : }
721 : : /* Check CRC and release memory */
722 : 0 : if (i == RETVAL_LAST_BLOCK) {
723 : 0 : if (bd->headerCRC != bd->totalCRC)
724 : 0 : error("Data integrity error when decompressing.");
725 : : else
726 : : i = RETVAL_OK;
727 : 0 : } else if (i == RETVAL_UNEXPECTED_OUTPUT_EOF) {
728 : 0 : error("Compressed file ends unexpectedly");
729 : : }
730 : 0 : if (!bd)
731 : : goto exit_1;
732 : 0 : if (bd->dbuf)
733 : 0 : large_free(bd->dbuf);
734 : 0 : if (pos)
735 : 0 : *pos = bd->inbufPos;
736 : 0 : free(bd);
737 : : exit_1:
738 : 0 : if (!buf)
739 : 0 : free(inbuf);
740 : : exit_0:
741 : 0 : if (flush)
742 : 0 : free(outbuf);
743 : 0 : 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
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