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