001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied. See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019
020 /*
021 * This package is based on the work done by Keiron Liddle, Aftex Software
022 * <keiron@aftexsw.com> to whom the Ant project is very grateful for his
023 * great code.
024 */
025 package org.apache.commons.compress.compressors.bzip2;
026
027 import java.io.IOException;
028 import java.io.InputStream;
029
030 import org.apache.commons.compress.compressors.CompressorInputStream;
031
032 /**
033 * An input stream that decompresses from the BZip2 format to be read as any other stream.
034 *
035 * @NotThreadSafe
036 */
037 public class BZip2CompressorInputStream extends CompressorInputStream implements
038 BZip2Constants {
039
040 /**
041 * Index of the last char in the block, so the block size == last + 1.
042 */
043 private int last;
044
045 /**
046 * Index in zptr[] of original string after sorting.
047 */
048 private int origPtr;
049
050 /**
051 * always: in the range 0 .. 9. The current block size is 100000 * this
052 * number.
053 */
054 private int blockSize100k;
055
056 private boolean blockRandomised;
057
058 private int bsBuff;
059 private int bsLive;
060 private final CRC crc = new CRC();
061
062 private int nInUse;
063
064 private InputStream in;
065
066 private int currentChar = -1;
067
068 private static final int EOF = 0;
069 private static final int START_BLOCK_STATE = 1;
070 private static final int RAND_PART_A_STATE = 2;
071 private static final int RAND_PART_B_STATE = 3;
072 private static final int RAND_PART_C_STATE = 4;
073 private static final int NO_RAND_PART_A_STATE = 5;
074 private static final int NO_RAND_PART_B_STATE = 6;
075 private static final int NO_RAND_PART_C_STATE = 7;
076
077 private int currentState = START_BLOCK_STATE;
078
079 private int storedBlockCRC, storedCombinedCRC;
080 private int computedBlockCRC, computedCombinedCRC;
081
082 // Variables used by setup* methods exclusively
083
084 private int su_count;
085 private int su_ch2;
086 private int su_chPrev;
087 private int su_i2;
088 private int su_j2;
089 private int su_rNToGo;
090 private int su_rTPos;
091 private int su_tPos;
092 private char su_z;
093
094 /**
095 * All memory intensive stuff. This field is initialized by initBlock().
096 */
097 private BZip2CompressorInputStream.Data data;
098
099 /**
100 * Constructs a new BZip2CompressorInputStream which decompresses bytes read from the
101 * specified stream.
102 *
103 * @throws IOException
104 * if the stream content is malformed or an I/O error occurs.
105 * @throws NullPointerException
106 * if <tt>in == null</tt>
107 */
108 public BZip2CompressorInputStream(final InputStream in) throws IOException {
109 super();
110
111 this.in = in;
112 init();
113 }
114
115 /** {@inheritDoc} */
116 @Override
117 public int read() throws IOException {
118 if (this.in != null) {
119 int r = read0();
120 count(r < 0 ? -1 : 1);
121 return r;
122 } else {
123 throw new IOException("stream closed");
124 }
125 }
126
127 /*
128 * (non-Javadoc)
129 *
130 * @see java.io.InputStream#read(byte[], int, int)
131 */
132 @Override
133 public int read(final byte[] dest, final int offs, final int len)
134 throws IOException {
135 if (offs < 0) {
136 throw new IndexOutOfBoundsException("offs(" + offs + ") < 0.");
137 }
138 if (len < 0) {
139 throw new IndexOutOfBoundsException("len(" + len + ") < 0.");
140 }
141 if (offs + len > dest.length) {
142 throw new IndexOutOfBoundsException("offs(" + offs + ") + len("
143 + len + ") > dest.length(" + dest.length + ").");
144 }
145 if (this.in == null) {
146 throw new IOException("stream closed");
147 }
148
149 final int hi = offs + len;
150 int destOffs = offs;
151 for (int b; (destOffs < hi) && ((b = read0()) >= 0);) {
152 dest[destOffs++] = (byte) b;
153 }
154
155 int c = (destOffs == offs) ? -1 : (destOffs - offs);
156 count(c);
157 return c;
158 }
159
160 private void makeMaps() {
161 final boolean[] inUse = this.data.inUse;
162 final byte[] seqToUnseq = this.data.seqToUnseq;
163
164 int nInUseShadow = 0;
165
166 for (int i = 0; i < 256; i++) {
167 if (inUse[i])
168 seqToUnseq[nInUseShadow++] = (byte) i;
169 }
170
171 this.nInUse = nInUseShadow;
172 }
173
174 private int read0() throws IOException {
175 final int retChar = this.currentChar;
176
177 switch (this.currentState) {
178 case EOF:
179 return -1;
180
181 case START_BLOCK_STATE:
182 throw new IllegalStateException();
183
184 case RAND_PART_A_STATE:
185 throw new IllegalStateException();
186
187 case RAND_PART_B_STATE:
188 setupRandPartB();
189 break;
190
191 case RAND_PART_C_STATE:
192 setupRandPartC();
193 break;
194
195 case NO_RAND_PART_A_STATE:
196 throw new IllegalStateException();
197
198 case NO_RAND_PART_B_STATE:
199 setupNoRandPartB();
200 break;
201
202 case NO_RAND_PART_C_STATE:
203 setupNoRandPartC();
204 break;
205
206 default:
207 throw new IllegalStateException();
208 }
209
210 return retChar;
211 }
212
213 private void init() throws IOException {
214 if (null == in) {
215 throw new IOException("No InputStream");
216 }
217 checkMagicChar('B', "first");
218 checkMagicChar('Z', "second");
219 checkMagicChar('h', "third");
220
221 int blockSize = this.in.read();
222 if ((blockSize < '1') || (blockSize > '9')) {
223 throw new IOException("Stream is not BZip2 formatted: illegal "
224 + "blocksize " + (char) blockSize);
225 }
226
227 this.blockSize100k = blockSize - '0';
228
229 initBlock();
230 setupBlock();
231 }
232
233 private void checkMagicChar(char expected, String position)
234 throws IOException {
235 int magic = this.in.read();
236 if (magic != expected) {
237 throw new IOException("Stream is not BZip2 formatted: expected '"
238 + expected + "' as " + position + " byte but got '"
239 + (char) magic + "'");
240 }
241 }
242
243 private void initBlock() throws IOException {
244 char magic0 = bsGetUByte();
245 char magic1 = bsGetUByte();
246 char magic2 = bsGetUByte();
247 char magic3 = bsGetUByte();
248 char magic4 = bsGetUByte();
249 char magic5 = bsGetUByte();
250
251 if (magic0 == 0x17 && magic1 == 0x72 && magic2 == 0x45
252 && magic3 == 0x38 && magic4 == 0x50 && magic5 == 0x90) {
253 complete(); // end of file
254 } else if (magic0 != 0x31 || // '1'
255 magic1 != 0x41 || // ')'
256 magic2 != 0x59 || // 'Y'
257 magic3 != 0x26 || // '&'
258 magic4 != 0x53 || // 'S'
259 magic5 != 0x59 // 'Y'
260 ) {
261 this.currentState = EOF;
262 throw new IOException("bad block header");
263 } else {
264 this.storedBlockCRC = bsGetInt();
265 this.blockRandomised = bsR(1) == 1;
266
267 /**
268 * Allocate data here instead in constructor, so we do not allocate
269 * it if the input file is empty.
270 */
271 if (this.data == null) {
272 this.data = new Data(this.blockSize100k);
273 }
274
275 // currBlockNo++;
276 getAndMoveToFrontDecode();
277
278 this.crc.initialiseCRC();
279 this.currentState = START_BLOCK_STATE;
280 }
281 }
282
283 private void endBlock() throws IOException {
284 this.computedBlockCRC = this.crc.getFinalCRC();
285
286 // A bad CRC is considered a fatal error.
287 if (this.storedBlockCRC != this.computedBlockCRC) {
288 // make next blocks readable without error
289 // (repair feature, not yet documented, not tested)
290 this.computedCombinedCRC = (this.storedCombinedCRC << 1)
291 | (this.storedCombinedCRC >>> 31);
292 this.computedCombinedCRC ^= this.storedBlockCRC;
293
294 throw new IOException("BZip2 CRC error");
295 }
296
297 this.computedCombinedCRC = (this.computedCombinedCRC << 1)
298 | (this.computedCombinedCRC >>> 31);
299 this.computedCombinedCRC ^= this.computedBlockCRC;
300 }
301
302 private void complete() throws IOException {
303 this.storedCombinedCRC = bsGetInt();
304 this.currentState = EOF;
305 this.data = null;
306
307 if (this.storedCombinedCRC != this.computedCombinedCRC) {
308 throw new IOException("BZip2 CRC error");
309 }
310 }
311
312 @Override
313 public void close() throws IOException {
314 InputStream inShadow = this.in;
315 if (inShadow != null) {
316 try {
317 if (inShadow != System.in) {
318 inShadow.close();
319 }
320 } finally {
321 this.data = null;
322 this.in = null;
323 }
324 }
325 }
326
327 private int bsR(final int n) throws IOException {
328 int bsLiveShadow = this.bsLive;
329 int bsBuffShadow = this.bsBuff;
330
331 if (bsLiveShadow < n) {
332 final InputStream inShadow = this.in;
333 do {
334 int thech = inShadow.read();
335
336 if (thech < 0) {
337 throw new IOException("unexpected end of stream");
338 }
339
340 bsBuffShadow = (bsBuffShadow << 8) | thech;
341 bsLiveShadow += 8;
342 } while (bsLiveShadow < n);
343
344 this.bsBuff = bsBuffShadow;
345 }
346
347 this.bsLive = bsLiveShadow - n;
348 return (bsBuffShadow >> (bsLiveShadow - n)) & ((1 << n) - 1);
349 }
350
351 private boolean bsGetBit() throws IOException {
352 int bsLiveShadow = this.bsLive;
353 int bsBuffShadow = this.bsBuff;
354
355 if (bsLiveShadow < 1) {
356 int thech = this.in.read();
357
358 if (thech < 0) {
359 throw new IOException("unexpected end of stream");
360 }
361
362 bsBuffShadow = (bsBuffShadow << 8) | thech;
363 bsLiveShadow += 8;
364 this.bsBuff = bsBuffShadow;
365 }
366
367 this.bsLive = bsLiveShadow - 1;
368 return ((bsBuffShadow >> (bsLiveShadow - 1)) & 1) != 0;
369 }
370
371 private char bsGetUByte() throws IOException {
372 return (char) bsR(8);
373 }
374
375 private int bsGetInt() throws IOException {
376 return (((((bsR(8) << 8) | bsR(8)) << 8) | bsR(8)) << 8) | bsR(8);
377 }
378
379 /**
380 * Called by createHuffmanDecodingTables() exclusively.
381 */
382 private static void hbCreateDecodeTables(final int[] limit,
383 final int[] base, final int[] perm, final char[] length,
384 final int minLen, final int maxLen, final int alphaSize) {
385 for (int i = minLen, pp = 0; i <= maxLen; i++) {
386 for (int j = 0; j < alphaSize; j++) {
387 if (length[j] == i) {
388 perm[pp++] = j;
389 }
390 }
391 }
392
393 for (int i = MAX_CODE_LEN; --i > 0;) {
394 base[i] = 0;
395 limit[i] = 0;
396 }
397
398 for (int i = 0; i < alphaSize; i++) {
399 base[length[i] + 1]++;
400 }
401
402 for (int i = 1, b = base[0]; i < MAX_CODE_LEN; i++) {
403 b += base[i];
404 base[i] = b;
405 }
406
407 for (int i = minLen, vec = 0, b = base[i]; i <= maxLen; i++) {
408 final int nb = base[i + 1];
409 vec += nb - b;
410 b = nb;
411 limit[i] = vec - 1;
412 vec <<= 1;
413 }
414
415 for (int i = minLen + 1; i <= maxLen; i++) {
416 base[i] = ((limit[i - 1] + 1) << 1) - base[i];
417 }
418 }
419
420 private void recvDecodingTables() throws IOException {
421 final Data dataShadow = this.data;
422 final boolean[] inUse = dataShadow.inUse;
423 final byte[] pos = dataShadow.recvDecodingTables_pos;
424 final byte[] selector = dataShadow.selector;
425 final byte[] selectorMtf = dataShadow.selectorMtf;
426
427 int inUse16 = 0;
428
429 /* Receive the mapping table */
430 for (int i = 0; i < 16; i++) {
431 if (bsGetBit()) {
432 inUse16 |= 1 << i;
433 }
434 }
435
436 for (int i = 256; --i >= 0;) {
437 inUse[i] = false;
438 }
439
440 for (int i = 0; i < 16; i++) {
441 if ((inUse16 & (1 << i)) != 0) {
442 final int i16 = i << 4;
443 for (int j = 0; j < 16; j++) {
444 if (bsGetBit()) {
445 inUse[i16 + j] = true;
446 }
447 }
448 }
449 }
450
451 makeMaps();
452 final int alphaSize = this.nInUse + 2;
453
454 /* Now the selectors */
455 final int nGroups = bsR(3);
456 final int nSelectors = bsR(15);
457
458 for (int i = 0; i < nSelectors; i++) {
459 int j = 0;
460 while (bsGetBit()) {
461 j++;
462 }
463 selectorMtf[i] = (byte) j;
464 }
465
466 /* Undo the MTF values for the selectors. */
467 for (int v = nGroups; --v >= 0;) {
468 pos[v] = (byte) v;
469 }
470
471 for (int i = 0; i < nSelectors; i++) {
472 int v = selectorMtf[i] & 0xff;
473 final byte tmp = pos[v];
474 while (v > 0) {
475 // nearly all times v is zero, 4 in most other cases
476 pos[v] = pos[v - 1];
477 v--;
478 }
479 pos[0] = tmp;
480 selector[i] = tmp;
481 }
482
483 final char[][] len = dataShadow.temp_charArray2d;
484
485 /* Now the coding tables */
486 for (int t = 0; t < nGroups; t++) {
487 int curr = bsR(5);
488 final char[] len_t = len[t];
489 for (int i = 0; i < alphaSize; i++) {
490 while (bsGetBit()) {
491 curr += bsGetBit() ? -1 : 1;
492 }
493 len_t[i] = (char) curr;
494 }
495 }
496
497 // finally create the Huffman tables
498 createHuffmanDecodingTables(alphaSize, nGroups);
499 }
500
501 /**
502 * Called by recvDecodingTables() exclusively.
503 */
504 private void createHuffmanDecodingTables(final int alphaSize,
505 final int nGroups) {
506 final Data dataShadow = this.data;
507 final char[][] len = dataShadow.temp_charArray2d;
508 final int[] minLens = dataShadow.minLens;
509 final int[][] limit = dataShadow.limit;
510 final int[][] base = dataShadow.base;
511 final int[][] perm = dataShadow.perm;
512
513 for (int t = 0; t < nGroups; t++) {
514 int minLen = 32;
515 int maxLen = 0;
516 final char[] len_t = len[t];
517 for (int i = alphaSize; --i >= 0;) {
518 final char lent = len_t[i];
519 if (lent > maxLen) {
520 maxLen = lent;
521 }
522 if (lent < minLen) {
523 minLen = lent;
524 }
525 }
526 hbCreateDecodeTables(limit[t], base[t], perm[t], len[t], minLen,
527 maxLen, alphaSize);
528 minLens[t] = minLen;
529 }
530 }
531
532 private void getAndMoveToFrontDecode() throws IOException {
533 this.origPtr = bsR(24);
534 recvDecodingTables();
535
536 final InputStream inShadow = this.in;
537 final Data dataShadow = this.data;
538 final byte[] ll8 = dataShadow.ll8;
539 final int[] unzftab = dataShadow.unzftab;
540 final byte[] selector = dataShadow.selector;
541 final byte[] seqToUnseq = dataShadow.seqToUnseq;
542 final char[] yy = dataShadow.getAndMoveToFrontDecode_yy;
543 final int[] minLens = dataShadow.minLens;
544 final int[][] limit = dataShadow.limit;
545 final int[][] base = dataShadow.base;
546 final int[][] perm = dataShadow.perm;
547 final int limitLast = this.blockSize100k * 100000;
548
549 /*
550 * Setting up the unzftab entries here is not strictly necessary, but it
551 * does save having to do it later in a separate pass, and so saves a
552 * block's worth of cache misses.
553 */
554 for (int i = 256; --i >= 0;) {
555 yy[i] = (char) i;
556 unzftab[i] = 0;
557 }
558
559 int groupNo = 0;
560 int groupPos = G_SIZE - 1;
561 final int eob = this.nInUse + 1;
562 int nextSym = getAndMoveToFrontDecode0(0);
563 int bsBuffShadow = this.bsBuff;
564 int bsLiveShadow = this.bsLive;
565 int lastShadow = -1;
566 int zt = selector[groupNo] & 0xff;
567 int[] base_zt = base[zt];
568 int[] limit_zt = limit[zt];
569 int[] perm_zt = perm[zt];
570 int minLens_zt = minLens[zt];
571
572 while (nextSym != eob) {
573 if ((nextSym == RUNA) || (nextSym == RUNB)) {
574 int s = -1;
575
576 for (int n = 1; true; n <<= 1) {
577 if (nextSym == RUNA) {
578 s += n;
579 } else if (nextSym == RUNB) {
580 s += n << 1;
581 } else {
582 break;
583 }
584
585 if (groupPos == 0) {
586 groupPos = G_SIZE - 1;
587 zt = selector[++groupNo] & 0xff;
588 base_zt = base[zt];
589 limit_zt = limit[zt];
590 perm_zt = perm[zt];
591 minLens_zt = minLens[zt];
592 } else {
593 groupPos--;
594 }
595
596 int zn = minLens_zt;
597
598 // Inlined:
599 // int zvec = bsR(zn);
600 while (bsLiveShadow < zn) {
601 final int thech = inShadow.read();
602 if (thech >= 0) {
603 bsBuffShadow = (bsBuffShadow << 8) | thech;
604 bsLiveShadow += 8;
605 continue;
606 } else {
607 throw new IOException("unexpected end of stream");
608 }
609 }
610 int zvec = (bsBuffShadow >> (bsLiveShadow - zn))
611 & ((1 << zn) - 1);
612 bsLiveShadow -= zn;
613
614 while (zvec > limit_zt[zn]) {
615 zn++;
616 while (bsLiveShadow < 1) {
617 final int thech = inShadow.read();
618 if (thech >= 0) {
619 bsBuffShadow = (bsBuffShadow << 8) | thech;
620 bsLiveShadow += 8;
621 continue;
622 } else {
623 throw new IOException(
624 "unexpected end of stream");
625 }
626 }
627 bsLiveShadow--;
628 zvec = (zvec << 1)
629 | ((bsBuffShadow >> bsLiveShadow) & 1);
630 }
631 nextSym = perm_zt[zvec - base_zt[zn]];
632 }
633
634 final byte ch = seqToUnseq[yy[0]];
635 unzftab[ch & 0xff] += s + 1;
636
637 while (s-- >= 0) {
638 ll8[++lastShadow] = ch;
639 }
640
641 if (lastShadow >= limitLast) {
642 throw new IOException("block overrun");
643 }
644 } else {
645 if (++lastShadow >= limitLast) {
646 throw new IOException("block overrun");
647 }
648
649 final char tmp = yy[nextSym - 1];
650 unzftab[seqToUnseq[tmp] & 0xff]++;
651 ll8[lastShadow] = seqToUnseq[tmp];
652
653 /*
654 * This loop is hammered during decompression, hence avoid
655 * native method call overhead of System.arraycopy for very
656 * small ranges to copy.
657 */
658 if (nextSym <= 16) {
659 for (int j = nextSym - 1; j > 0;) {
660 yy[j] = yy[--j];
661 }
662 } else {
663 System.arraycopy(yy, 0, yy, 1, nextSym - 1);
664 }
665
666 yy[0] = tmp;
667
668 if (groupPos == 0) {
669 groupPos = G_SIZE - 1;
670 zt = selector[++groupNo] & 0xff;
671 base_zt = base[zt];
672 limit_zt = limit[zt];
673 perm_zt = perm[zt];
674 minLens_zt = minLens[zt];
675 } else {
676 groupPos--;
677 }
678
679 int zn = minLens_zt;
680
681 // Inlined:
682 // int zvec = bsR(zn);
683 while (bsLiveShadow < zn) {
684 final int thech = inShadow.read();
685 if (thech >= 0) {
686 bsBuffShadow = (bsBuffShadow << 8) | thech;
687 bsLiveShadow += 8;
688 continue;
689 } else {
690 throw new IOException("unexpected end of stream");
691 }
692 }
693 int zvec = (bsBuffShadow >> (bsLiveShadow - zn))
694 & ((1 << zn) - 1);
695 bsLiveShadow -= zn;
696
697 while (zvec > limit_zt[zn]) {
698 zn++;
699 while (bsLiveShadow < 1) {
700 final int thech = inShadow.read();
701 if (thech >= 0) {
702 bsBuffShadow = (bsBuffShadow << 8) | thech;
703 bsLiveShadow += 8;
704 continue;
705 } else {
706 throw new IOException("unexpected end of stream");
707 }
708 }
709 bsLiveShadow--;
710 zvec = (zvec << 1) | ((bsBuffShadow >> bsLiveShadow) & 1);
711 }
712 nextSym = perm_zt[zvec - base_zt[zn]];
713 }
714 }
715
716 this.last = lastShadow;
717 this.bsLive = bsLiveShadow;
718 this.bsBuff = bsBuffShadow;
719 }
720
721 private int getAndMoveToFrontDecode0(final int groupNo) throws IOException {
722 final InputStream inShadow = this.in;
723 final Data dataShadow = this.data;
724 final int zt = dataShadow.selector[groupNo] & 0xff;
725 final int[] limit_zt = dataShadow.limit[zt];
726 int zn = dataShadow.minLens[zt];
727 int zvec = bsR(zn);
728 int bsLiveShadow = this.bsLive;
729 int bsBuffShadow = this.bsBuff;
730
731 while (zvec > limit_zt[zn]) {
732 zn++;
733 while (bsLiveShadow < 1) {
734 final int thech = inShadow.read();
735
736 if (thech >= 0) {
737 bsBuffShadow = (bsBuffShadow << 8) | thech;
738 bsLiveShadow += 8;
739 continue;
740 } else {
741 throw new IOException("unexpected end of stream");
742 }
743 }
744 bsLiveShadow--;
745 zvec = (zvec << 1) | ((bsBuffShadow >> bsLiveShadow) & 1);
746 }
747
748 this.bsLive = bsLiveShadow;
749 this.bsBuff = bsBuffShadow;
750
751 return dataShadow.perm[zt][zvec - dataShadow.base[zt][zn]];
752 }
753
754 private void setupBlock() throws IOException {
755 if (this.data == null) {
756 return;
757 }
758
759 final int[] cftab = this.data.cftab;
760 final int[] tt = this.data.initTT(this.last + 1);
761 final byte[] ll8 = this.data.ll8;
762 cftab[0] = 0;
763 System.arraycopy(this.data.unzftab, 0, cftab, 1, 256);
764
765 for (int i = 1, c = cftab[0]; i <= 256; i++) {
766 c += cftab[i];
767 cftab[i] = c;
768 }
769
770 for (int i = 0, lastShadow = this.last; i <= lastShadow; i++) {
771 tt[cftab[ll8[i] & 0xff]++] = i;
772 }
773
774 if ((this.origPtr < 0) || (this.origPtr >= tt.length)) {
775 throw new IOException("stream corrupted");
776 }
777
778 this.su_tPos = tt[this.origPtr];
779 this.su_count = 0;
780 this.su_i2 = 0;
781 this.su_ch2 = 256; /* not a char and not EOF */
782
783 if (this.blockRandomised) {
784 this.su_rNToGo = 0;
785 this.su_rTPos = 0;
786 setupRandPartA();
787 } else {
788 setupNoRandPartA();
789 }
790 }
791
792 private void setupRandPartA() throws IOException {
793 if (this.su_i2 <= this.last) {
794 this.su_chPrev = this.su_ch2;
795 int su_ch2Shadow = this.data.ll8[this.su_tPos] & 0xff;
796 this.su_tPos = this.data.tt[this.su_tPos];
797 if (this.su_rNToGo == 0) {
798 this.su_rNToGo = Rand.rNums(this.su_rTPos) - 1;
799 if (++this.su_rTPos == 512) {
800 this.su_rTPos = 0;
801 }
802 } else {
803 this.su_rNToGo--;
804 }
805 this.su_ch2 = su_ch2Shadow ^= (this.su_rNToGo == 1) ? 1 : 0;
806 this.su_i2++;
807 this.currentChar = su_ch2Shadow;
808 this.currentState = RAND_PART_B_STATE;
809 this.crc.updateCRC(su_ch2Shadow);
810 } else {
811 endBlock();
812 initBlock();
813 setupBlock();
814 }
815 }
816
817 private void setupNoRandPartA() throws IOException {
818 if (this.su_i2 <= this.last) {
819 this.su_chPrev = this.su_ch2;
820 int su_ch2Shadow = this.data.ll8[this.su_tPos] & 0xff;
821 this.su_ch2 = su_ch2Shadow;
822 this.su_tPos = this.data.tt[this.su_tPos];
823 this.su_i2++;
824 this.currentChar = su_ch2Shadow;
825 this.currentState = NO_RAND_PART_B_STATE;
826 this.crc.updateCRC(su_ch2Shadow);
827 } else {
828 this.currentState = NO_RAND_PART_A_STATE;
829 endBlock();
830 initBlock();
831 setupBlock();
832 }
833 }
834
835 private void setupRandPartB() throws IOException {
836 if (this.su_ch2 != this.su_chPrev) {
837 this.currentState = RAND_PART_A_STATE;
838 this.su_count = 1;
839 setupRandPartA();
840 } else if (++this.su_count >= 4) {
841 this.su_z = (char) (this.data.ll8[this.su_tPos] & 0xff);
842 this.su_tPos = this.data.tt[this.su_tPos];
843 if (this.su_rNToGo == 0) {
844 this.su_rNToGo = Rand.rNums(this.su_rTPos) - 1;
845 if (++this.su_rTPos == 512) {
846 this.su_rTPos = 0;
847 }
848 } else {
849 this.su_rNToGo--;
850 }
851 this.su_j2 = 0;
852 this.currentState = RAND_PART_C_STATE;
853 if (this.su_rNToGo == 1) {
854 this.su_z ^= 1;
855 }
856 setupRandPartC();
857 } else {
858 this.currentState = RAND_PART_A_STATE;
859 setupRandPartA();
860 }
861 }
862
863 private void setupRandPartC() throws IOException {
864 if (this.su_j2 < this.su_z) {
865 this.currentChar = this.su_ch2;
866 this.crc.updateCRC(this.su_ch2);
867 this.su_j2++;
868 } else {
869 this.currentState = RAND_PART_A_STATE;
870 this.su_i2++;
871 this.su_count = 0;
872 setupRandPartA();
873 }
874 }
875
876 private void setupNoRandPartB() throws IOException {
877 if (this.su_ch2 != this.su_chPrev) {
878 this.su_count = 1;
879 setupNoRandPartA();
880 } else if (++this.su_count >= 4) {
881 this.su_z = (char) (this.data.ll8[this.su_tPos] & 0xff);
882 this.su_tPos = this.data.tt[this.su_tPos];
883 this.su_j2 = 0;
884 setupNoRandPartC();
885 } else {
886 setupNoRandPartA();
887 }
888 }
889
890 private void setupNoRandPartC() throws IOException {
891 if (this.su_j2 < this.su_z) {
892 int su_ch2Shadow = this.su_ch2;
893 this.currentChar = su_ch2Shadow;
894 this.crc.updateCRC(su_ch2Shadow);
895 this.su_j2++;
896 this.currentState = NO_RAND_PART_C_STATE;
897 } else {
898 this.su_i2++;
899 this.su_count = 0;
900 setupNoRandPartA();
901 }
902 }
903
904 private static final class Data extends Object {
905
906 // (with blockSize 900k)
907 final boolean[] inUse = new boolean[256]; // 256 byte
908
909 final byte[] seqToUnseq = new byte[256]; // 256 byte
910 final byte[] selector = new byte[MAX_SELECTORS]; // 18002 byte
911 final byte[] selectorMtf = new byte[MAX_SELECTORS]; // 18002 byte
912
913 /**
914 * Freq table collected to save a pass over the data during
915 * decompression.
916 */
917 final int[] unzftab = new int[256]; // 1024 byte
918
919 final int[][] limit = new int[N_GROUPS][MAX_ALPHA_SIZE]; // 6192 byte
920 final int[][] base = new int[N_GROUPS][MAX_ALPHA_SIZE]; // 6192 byte
921 final int[][] perm = new int[N_GROUPS][MAX_ALPHA_SIZE]; // 6192 byte
922 final int[] minLens = new int[N_GROUPS]; // 24 byte
923
924 final int[] cftab = new int[257]; // 1028 byte
925 final char[] getAndMoveToFrontDecode_yy = new char[256]; // 512 byte
926 final char[][] temp_charArray2d = new char[N_GROUPS][MAX_ALPHA_SIZE]; // 3096
927 // byte
928 final byte[] recvDecodingTables_pos = new byte[N_GROUPS]; // 6 byte
929 // ---------------
930 // 60798 byte
931
932 int[] tt; // 3600000 byte
933 byte[] ll8; // 900000 byte
934
935 // ---------------
936 // 4560782 byte
937 // ===============
938
939 Data(int blockSize100k) {
940 super();
941
942 this.ll8 = new byte[blockSize100k * BZip2Constants.BASEBLOCKSIZE];
943 }
944
945 /**
946 * Initializes the {@link #tt} array.
947 *
948 * This method is called when the required length of the array is known.
949 * I don't initialize it at construction time to avoid unneccessary
950 * memory allocation when compressing small files.
951 */
952 int[] initTT(int length) {
953 int[] ttShadow = this.tt;
954
955 // tt.length should always be >= length, but theoretically
956 // it can happen, if the compressor mixed small and large
957 // blocks. Normally only the last block will be smaller
958 // than others.
959 if ((ttShadow == null) || (ttShadow.length < length)) {
960 this.tt = ttShadow = new int[length];
961 }
962
963 return ttShadow;
964 }
965
966 }
967
968 /**
969 * Checks if the signature matches what is expected for a bzip2 file.
970 *
971 * @param signature
972 * the bytes to check
973 * @param length
974 * the number of bytes to check
975 * @return true, if this stream is a bzip2 compressed stream, false otherwise
976 *
977 * @since Apache Commons Compress 1.1
978 */
979 public static boolean matches(byte[] signature, int length) {
980
981 if (length < 3) {
982 return false;
983 }
984
985 if (signature[0] != 'B') {
986 return false;
987 }
988
989 if (signature[1] != 'Z') {
990 return false;
991 }
992
993 if (signature[2] != 'h') {
994 return false;
995 }
996
997 return true;
998 }
999 }