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 */ 025package org.apache.commons.compress.compressors.bzip2; 026 027import java.io.IOException; 028import java.io.InputStream; 029import java.nio.ByteOrder; 030import java.util.Arrays; 031 032import org.apache.commons.compress.compressors.CompressorInputStream; 033import org.apache.commons.compress.utils.BitInputStream; 034import org.apache.commons.compress.utils.CloseShieldFilterInputStream; 035 036/** 037 * An input stream that decompresses from the BZip2 format to be read as any other stream. 038 * 039 * @NotThreadSafe 040 */ 041public class BZip2CompressorInputStream extends CompressorInputStream implements 042 BZip2Constants { 043 044 /** 045 * Index of the last char in the block, so the block size == last + 1. 046 */ 047 private int last; 048 049 /** 050 * Index in zptr[] of original string after sorting. 051 */ 052 private int origPtr; 053 054 /** 055 * always: in the range 0 .. 9. The current block size is 100000 * this 056 * number. 057 */ 058 private int blockSize100k; 059 060 private boolean blockRandomised; 061 062 private final CRC crc = new CRC(); 063 064 private int nInUse; 065 066 private BitInputStream bin; 067 private final boolean decompressConcatenated; 068 069 private static final int EOF = 0; 070 private static final int START_BLOCK_STATE = 1; 071 private static final int RAND_PART_A_STATE = 2; 072 private static final int RAND_PART_B_STATE = 3; 073 private static final int RAND_PART_C_STATE = 4; 074 private static final int NO_RAND_PART_A_STATE = 5; 075 private static final int NO_RAND_PART_B_STATE = 6; 076 private static final int NO_RAND_PART_C_STATE = 7; 077 078 private int currentState = START_BLOCK_STATE; 079 080 private int storedBlockCRC, storedCombinedCRC; 081 private int computedBlockCRC, computedCombinedCRC; 082 083 // Variables used by setup* methods exclusively 084 085 private int su_count; 086 private int su_ch2; 087 private int su_chPrev; 088 private int su_i2; 089 private int su_j2; 090 private int su_rNToGo; 091 private int su_rTPos; 092 private int su_tPos; 093 private char su_z; 094 095 /** 096 * All memory intensive stuff. This field is initialized by initBlock(). 097 */ 098 private BZip2CompressorInputStream.Data data; 099 100 /** 101 * Constructs a new BZip2CompressorInputStream which decompresses bytes 102 * read from the specified stream. This doesn't suppprt decompressing 103 * concatenated .bz2 files. 104 * 105 * @param in the InputStream from which this object should be created 106 * @throws IOException 107 * if the stream content is malformed or an I/O error occurs. 108 * @throws NullPointerException 109 * if {@code in == null} 110 */ 111 public BZip2CompressorInputStream(final InputStream in) throws IOException { 112 this(in, false); 113 } 114 115 /** 116 * Constructs a new BZip2CompressorInputStream which decompresses bytes 117 * read from the specified stream. 118 * 119 * @param in the InputStream from which this object should be created 120 * @param decompressConcatenated 121 * if true, decompress until the end of the input; 122 * if false, stop after the first .bz2 stream and 123 * leave the input position to point to the next 124 * byte after the .bz2 stream 125 * 126 * @throws IOException 127 * if {@code in == null}, the stream content is malformed, or an I/O error occurs. 128 */ 129 public BZip2CompressorInputStream(final InputStream in, final boolean decompressConcatenated) throws IOException { 130 this.bin = new BitInputStream(in == System.in ? new CloseShieldFilterInputStream(in) : in, 131 ByteOrder.BIG_ENDIAN); 132 this.decompressConcatenated = decompressConcatenated; 133 134 init(true); 135 initBlock(); 136 } 137 138 @Override 139 public int read() throws IOException { 140 if (this.bin != null) { 141 final int r = read0(); 142 count(r < 0 ? -1 : 1); 143 return r; 144 } 145 throw new IOException("stream closed"); 146 } 147 148 /* 149 * (non-Javadoc) 150 * 151 * @see java.io.InputStream#read(byte[], int, int) 152 */ 153 @Override 154 public int read(final byte[] dest, final int offs, final int len) 155 throws IOException { 156 if (offs < 0) { 157 throw new IndexOutOfBoundsException("offs(" + offs + ") < 0."); 158 } 159 if (len < 0) { 160 throw new IndexOutOfBoundsException("len(" + len + ") < 0."); 161 } 162 if (offs + len > dest.length) { 163 throw new IndexOutOfBoundsException("offs(" + offs + ") + len(" 164 + len + ") > dest.length(" + dest.length + ")."); 165 } 166 if (this.bin == null) { 167 throw new IOException("stream closed"); 168 } 169 if (len == 0) { 170 return 0; 171 } 172 173 final int hi = offs + len; 174 int destOffs = offs; 175 int b; 176 while (destOffs < hi && ((b = read0()) >= 0)) { 177 dest[destOffs++] = (byte) b; 178 count(1); 179 } 180 181 final int c = (destOffs == offs) ? -1 : (destOffs - offs); 182 return c; 183 } 184 185 private void makeMaps() { 186 final boolean[] inUse = this.data.inUse; 187 final byte[] seqToUnseq = this.data.seqToUnseq; 188 189 int nInUseShadow = 0; 190 191 for (int i = 0; i < 256; i++) { 192 if (inUse[i]) { 193 seqToUnseq[nInUseShadow++] = (byte) i; 194 } 195 } 196 197 this.nInUse = nInUseShadow; 198 } 199 200 private int read0() throws IOException { 201 switch (currentState) { 202 case EOF: 203 return -1; 204 205 case START_BLOCK_STATE: 206 return setupBlock(); 207 208 case RAND_PART_A_STATE: 209 throw new IllegalStateException(); 210 211 case RAND_PART_B_STATE: 212 return setupRandPartB(); 213 214 case RAND_PART_C_STATE: 215 return setupRandPartC(); 216 217 case NO_RAND_PART_A_STATE: 218 throw new IllegalStateException(); 219 220 case NO_RAND_PART_B_STATE: 221 return setupNoRandPartB(); 222 223 case NO_RAND_PART_C_STATE: 224 return setupNoRandPartC(); 225 226 default: 227 throw new IllegalStateException(); 228 } 229 } 230 231 private int readNextByte(BitInputStream in) throws IOException { 232 long b = in.readBits(8); 233 return (int) b; 234 } 235 236 private boolean init(final boolean isFirstStream) throws IOException { 237 if (null == bin) { 238 throw new IOException("No InputStream"); 239 } 240 241 if (!isFirstStream) { 242 bin.clearBitCache(); 243 } 244 245 final int magic0 = readNextByte(this.bin); 246 if (magic0 == -1 && !isFirstStream) { 247 return false; 248 } 249 final int magic1 = readNextByte(this.bin); 250 final int magic2 = readNextByte(this.bin); 251 252 if (magic0 != 'B' || magic1 != 'Z' || magic2 != 'h') { 253 throw new IOException(isFirstStream 254 ? "Stream is not in the BZip2 format" 255 : "Garbage after a valid BZip2 stream"); 256 } 257 258 final int blockSize = readNextByte(this.bin); 259 if ((blockSize < '1') || (blockSize > '9')) { 260 throw new IOException("BZip2 block size is invalid"); 261 } 262 263 this.blockSize100k = blockSize - '0'; 264 265 this.computedCombinedCRC = 0; 266 267 return true; 268 } 269 270 private void initBlock() throws IOException { 271 BitInputStream bin = this.bin; 272 char magic0; 273 char magic1; 274 char magic2; 275 char magic3; 276 char magic4; 277 char magic5; 278 279 while (true) { 280 // Get the block magic bytes. 281 magic0 = bsGetUByte(bin); 282 magic1 = bsGetUByte(bin); 283 magic2 = bsGetUByte(bin); 284 magic3 = bsGetUByte(bin); 285 magic4 = bsGetUByte(bin); 286 magic5 = bsGetUByte(bin); 287 288 // If isn't end of stream magic, break out of the loop. 289 if (magic0 != 0x17 || magic1 != 0x72 || magic2 != 0x45 290 || magic3 != 0x38 || magic4 != 0x50 || magic5 != 0x90) { 291 break; 292 } 293 294 // End of stream was reached. Check the combined CRC and 295 // advance to the next .bz2 stream if decoding concatenated 296 // streams. 297 if (complete()) { 298 return; 299 } 300 } 301 302 if (magic0 != 0x31 || // '1' 303 magic1 != 0x41 || // ')' 304 magic2 != 0x59 || // 'Y' 305 magic3 != 0x26 || // '&' 306 magic4 != 0x53 || // 'S' 307 magic5 != 0x59 // 'Y' 308 ) { 309 this.currentState = EOF; 310 throw new IOException("bad block header"); 311 } 312 this.storedBlockCRC = bsGetInt(bin); 313 this.blockRandomised = bsR(bin, 1) == 1; 314 315 /** 316 * Allocate data here instead in constructor, so we do not allocate 317 * it if the input file is empty. 318 */ 319 if (this.data == null) { 320 this.data = new Data(this.blockSize100k); 321 } 322 323 // currBlockNo++; 324 getAndMoveToFrontDecode(); 325 326 this.crc.initialiseCRC(); 327 this.currentState = START_BLOCK_STATE; 328 } 329 330 private void endBlock() throws IOException { 331 this.computedBlockCRC = this.crc.getFinalCRC(); 332 333 // A bad CRC is considered a fatal error. 334 if (this.storedBlockCRC != this.computedBlockCRC) { 335 // make next blocks readable without error 336 // (repair feature, not yet documented, not tested) 337 this.computedCombinedCRC = (this.storedCombinedCRC << 1) 338 | (this.storedCombinedCRC >>> 31); 339 this.computedCombinedCRC ^= this.storedBlockCRC; 340 341 throw new IOException("BZip2 CRC error"); 342 } 343 344 this.computedCombinedCRC = (this.computedCombinedCRC << 1) 345 | (this.computedCombinedCRC >>> 31); 346 this.computedCombinedCRC ^= this.computedBlockCRC; 347 } 348 349 private boolean complete() throws IOException { 350 this.storedCombinedCRC = bsGetInt(bin); 351 this.currentState = EOF; 352 this.data = null; 353 354 if (this.storedCombinedCRC != this.computedCombinedCRC) { 355 throw new IOException("BZip2 CRC error"); 356 } 357 358 // Look for the next .bz2 stream if decompressing 359 // concatenated files. 360 return !decompressConcatenated || !init(false); 361 } 362 363 @Override 364 public void close() throws IOException { 365 final BitInputStream inShadow = this.bin; 366 if (inShadow != null) { 367 try { 368 inShadow.close(); 369 } finally { 370 this.data = null; 371 this.bin = null; 372 } 373 } 374 } 375 376 /** 377 * read bits from the input stream 378 * @param n the number of bits to read, must not exceed 32? 379 * @return 380 * @throws IOException 381 */ 382 private static int bsR(BitInputStream bin, final int n) throws IOException { 383 long thech = bin.readBits(n); 384 if (thech < 0) { 385 throw new IOException("unexpected end of stream"); 386 } 387 return (int) thech; 388 } 389 390 private static boolean bsGetBit(BitInputStream bin) throws IOException { 391 return bsR(bin, 1) != 0; 392 } 393 394 private static char bsGetUByte(BitInputStream bin) throws IOException { 395 return (char) bsR(bin, 8); 396 } 397 398 private static int bsGetInt(BitInputStream bin) throws IOException { 399 return bsR(bin, 32); 400 } 401 402 /** 403 * Called by createHuffmanDecodingTables() exclusively. 404 */ 405 private static void hbCreateDecodeTables(final int[] limit, 406 final int[] base, final int[] perm, final char[] length, 407 final int minLen, final int maxLen, final int alphaSize) { 408 for (int i = minLen, pp = 0; i <= maxLen; i++) { 409 for (int j = 0; j < alphaSize; j++) { 410 if (length[j] == i) { 411 perm[pp++] = j; 412 } 413 } 414 } 415 416 for (int i = MAX_CODE_LEN; --i > 0;) { 417 base[i] = 0; 418 limit[i] = 0; 419 } 420 421 for (int i = 0; i < alphaSize; i++) { 422 base[length[i] + 1]++; 423 } 424 425 for (int i = 1, b = base[0]; i < MAX_CODE_LEN; i++) { 426 b += base[i]; 427 base[i] = b; 428 } 429 430 for (int i = minLen, vec = 0, b = base[i]; i <= maxLen; i++) { 431 final int nb = base[i + 1]; 432 vec += nb - b; 433 b = nb; 434 limit[i] = vec - 1; 435 vec <<= 1; 436 } 437 438 for (int i = minLen + 1; i <= maxLen; i++) { 439 base[i] = ((limit[i - 1] + 1) << 1) - base[i]; 440 } 441 } 442 443 private void recvDecodingTables() throws IOException { 444 final BitInputStream bin = this.bin; 445 final Data dataShadow = this.data; 446 final boolean[] inUse = dataShadow.inUse; 447 final byte[] pos = dataShadow.recvDecodingTables_pos; 448 final byte[] selector = dataShadow.selector; 449 final byte[] selectorMtf = dataShadow.selectorMtf; 450 451 int inUse16 = 0; 452 453 /* Receive the mapping table */ 454 for (int i = 0; i < 16; i++) { 455 if (bsGetBit(bin)) { 456 inUse16 |= 1 << i; 457 } 458 } 459 460 Arrays.fill(inUse, false); 461 for (int i = 0; i < 16; i++) { 462 if ((inUse16 & (1 << i)) != 0) { 463 final int i16 = i << 4; 464 for (int j = 0; j < 16; j++) { 465 if (bsGetBit(bin)) { 466 inUse[i16 + j] = true; 467 } 468 } 469 } 470 } 471 472 makeMaps(); 473 final int alphaSize = this.nInUse + 2; 474 /* Now the selectors */ 475 final int nGroups = bsR(bin, 3); 476 final int nSelectors = bsR(bin, 15); 477 478 for (int i = 0; i < nSelectors; i++) { 479 int j = 0; 480 while (bsGetBit(bin)) { 481 j++; 482 } 483 selectorMtf[i] = (byte) j; 484 } 485 486 /* Undo the MTF values for the selectors. */ 487 for (int v = nGroups; --v >= 0;) { 488 pos[v] = (byte) v; 489 } 490 491 for (int i = 0; i < nSelectors; i++) { 492 int v = selectorMtf[i] & 0xff; 493 final byte tmp = pos[v]; 494 while (v > 0) { 495 // nearly all times v is zero, 4 in most other cases 496 pos[v] = pos[v - 1]; 497 v--; 498 } 499 pos[0] = tmp; 500 selector[i] = tmp; 501 } 502 503 final char[][] len = dataShadow.temp_charArray2d; 504 505 /* Now the coding tables */ 506 for (int t = 0; t < nGroups; t++) { 507 int curr = bsR(bin, 5); 508 final char[] len_t = len[t]; 509 for (int i = 0; i < alphaSize; i++) { 510 while (bsGetBit(bin)) { 511 curr += bsGetBit(bin) ? -1 : 1; 512 } 513 len_t[i] = (char) curr; 514 } 515 } 516 517 // finally create the Huffman tables 518 createHuffmanDecodingTables(alphaSize, nGroups); 519 } 520 521 /** 522 * Called by recvDecodingTables() exclusively. 523 */ 524 private void createHuffmanDecodingTables(final int alphaSize, 525 final int nGroups) { 526 final Data dataShadow = this.data; 527 final char[][] len = dataShadow.temp_charArray2d; 528 final int[] minLens = dataShadow.minLens; 529 final int[][] limit = dataShadow.limit; 530 final int[][] base = dataShadow.base; 531 final int[][] perm = dataShadow.perm; 532 533 for (int t = 0; t < nGroups; t++) { 534 int minLen = 32; 535 int maxLen = 0; 536 final char[] len_t = len[t]; 537 for (int i = alphaSize; --i >= 0;) { 538 final char lent = len_t[i]; 539 if (lent > maxLen) { 540 maxLen = lent; 541 } 542 if (lent < minLen) { 543 minLen = lent; 544 } 545 } 546 hbCreateDecodeTables(limit[t], base[t], perm[t], len[t], minLen, 547 maxLen, alphaSize); 548 minLens[t] = minLen; 549 } 550 } 551 552 private void getAndMoveToFrontDecode() throws IOException { 553 final BitInputStream bin = this.bin; 554 this.origPtr = bsR(bin, 24); 555 recvDecodingTables(); 556 557 final Data dataShadow = this.data; 558 final byte[] ll8 = dataShadow.ll8; 559 final int[] unzftab = dataShadow.unzftab; 560 final byte[] selector = dataShadow.selector; 561 final byte[] seqToUnseq = dataShadow.seqToUnseq; 562 final char[] yy = dataShadow.getAndMoveToFrontDecode_yy; 563 final int[] minLens = dataShadow.minLens; 564 final int[][] limit = dataShadow.limit; 565 final int[][] base = dataShadow.base; 566 final int[][] perm = dataShadow.perm; 567 final int limitLast = this.blockSize100k * 100000; 568 569 /* 570 * Setting up the unzftab entries here is not strictly necessary, but it 571 * does save having to do it later in a separate pass, and so saves a 572 * block's worth of cache misses. 573 */ 574 for (int i = 256; --i >= 0;) { 575 yy[i] = (char) i; 576 unzftab[i] = 0; 577 } 578 579 int groupNo = 0; 580 int groupPos = G_SIZE - 1; 581 final int eob = this.nInUse + 1; 582 int nextSym = getAndMoveToFrontDecode0(0); 583 int lastShadow = -1; 584 int zt = selector[groupNo] & 0xff; 585 int[] base_zt = base[zt]; 586 int[] limit_zt = limit[zt]; 587 int[] perm_zt = perm[zt]; 588 int minLens_zt = minLens[zt]; 589 590 while (nextSym != eob) { 591 if ((nextSym == RUNA) || (nextSym == RUNB)) { 592 int s = -1; 593 594 for (int n = 1; true; n <<= 1) { 595 if (nextSym == RUNA) { 596 s += n; 597 } else if (nextSym == RUNB) { 598 s += n << 1; 599 } else { 600 break; 601 } 602 603 if (groupPos == 0) { 604 groupPos = G_SIZE - 1; 605 zt = selector[++groupNo] & 0xff; 606 base_zt = base[zt]; 607 limit_zt = limit[zt]; 608 perm_zt = perm[zt]; 609 minLens_zt = minLens[zt]; 610 } else { 611 groupPos--; 612 } 613 614 int zn = minLens_zt; 615 int zvec = bsR(bin, zn); 616 while(zvec > limit_zt[zn]) { 617 zn++; 618 zvec = (zvec << 1) | bsR(bin, 1); 619 } 620 nextSym = perm_zt[zvec - base_zt[zn]]; 621 } 622 623 final byte ch = seqToUnseq[yy[0]]; 624 unzftab[ch & 0xff] += s + 1; 625 626 while (s-- >= 0) { 627 ll8[++lastShadow] = ch; 628 } 629 630 if (lastShadow >= limitLast) { 631 throw new IOException("block overrun"); 632 } 633 } else { 634 if (++lastShadow >= limitLast) { 635 throw new IOException("block overrun"); 636 } 637 638 final char tmp = yy[nextSym - 1]; 639 unzftab[seqToUnseq[tmp] & 0xff]++; 640 ll8[lastShadow] = seqToUnseq[tmp]; 641 642 /* 643 * This loop is hammered during decompression, hence avoid 644 * native method call overhead of System.arraycopy for very 645 * small ranges to copy. 646 */ 647 if (nextSym <= 16) { 648 for (int j = nextSym - 1; j > 0;) { 649 yy[j] = yy[--j]; 650 } 651 } else { 652 System.arraycopy(yy, 0, yy, 1, nextSym - 1); 653 } 654 655 yy[0] = tmp; 656 657 if (groupPos == 0) { 658 groupPos = G_SIZE - 1; 659 zt = selector[++groupNo] & 0xff; 660 base_zt = base[zt]; 661 limit_zt = limit[zt]; 662 perm_zt = perm[zt]; 663 minLens_zt = minLens[zt]; 664 } else { 665 groupPos--; 666 } 667 668 int zn = minLens_zt; 669 int zvec = bsR(bin, zn); 670 while(zvec > limit_zt[zn]) { 671 zn++; 672 zvec = (zvec << 1) | bsR(bin, 1); 673 } 674 nextSym = perm_zt[zvec - base_zt[zn]]; 675 } 676 } 677 678 this.last = lastShadow; 679 } 680 681 private int getAndMoveToFrontDecode0(final int groupNo) throws IOException { 682 final Data dataShadow = this.data; 683 final int zt = dataShadow.selector[groupNo] & 0xff; 684 final int[] limit_zt = dataShadow.limit[zt]; 685 int zn = dataShadow.minLens[zt]; 686 int zvec = bsR(bin, zn); 687 while (zvec > limit_zt[zn]) { 688 zn++; 689 zvec = (zvec << 1) | bsR(bin, 1); 690 } 691 692 return dataShadow.perm[zt][zvec - dataShadow.base[zt][zn]]; 693 } 694 695 private int setupBlock() throws IOException { 696 if (currentState == EOF || this.data == null) { 697 return -1; 698 } 699 700 final int[] cftab = this.data.cftab; 701 final int[] tt = this.data.initTT(this.last + 1); 702 final byte[] ll8 = this.data.ll8; 703 cftab[0] = 0; 704 System.arraycopy(this.data.unzftab, 0, cftab, 1, 256); 705 706 for (int i = 1, c = cftab[0]; i <= 256; i++) { 707 c += cftab[i]; 708 cftab[i] = c; 709 } 710 711 for (int i = 0, lastShadow = this.last; i <= lastShadow; i++) { 712 tt[cftab[ll8[i] & 0xff]++] = i; 713 } 714 715 if ((this.origPtr < 0) || (this.origPtr >= tt.length)) { 716 throw new IOException("stream corrupted"); 717 } 718 719 this.su_tPos = tt[this.origPtr]; 720 this.su_count = 0; 721 this.su_i2 = 0; 722 this.su_ch2 = 256; /* not a char and not EOF */ 723 724 if (this.blockRandomised) { 725 this.su_rNToGo = 0; 726 this.su_rTPos = 0; 727 return setupRandPartA(); 728 } 729 return setupNoRandPartA(); 730 } 731 732 private int setupRandPartA() throws IOException { 733 if (this.su_i2 <= this.last) { 734 this.su_chPrev = this.su_ch2; 735 int su_ch2Shadow = this.data.ll8[this.su_tPos] & 0xff; 736 this.su_tPos = this.data.tt[this.su_tPos]; 737 if (this.su_rNToGo == 0) { 738 this.su_rNToGo = Rand.rNums(this.su_rTPos) - 1; 739 if (++this.su_rTPos == 512) { 740 this.su_rTPos = 0; 741 } 742 } else { 743 this.su_rNToGo--; 744 } 745 this.su_ch2 = su_ch2Shadow ^= (this.su_rNToGo == 1) ? 1 : 0; 746 this.su_i2++; 747 this.currentState = RAND_PART_B_STATE; 748 this.crc.updateCRC(su_ch2Shadow); 749 return su_ch2Shadow; 750 } 751 endBlock(); 752 initBlock(); 753 return setupBlock(); 754 } 755 756 private int setupNoRandPartA() throws IOException { 757 if (this.su_i2 <= this.last) { 758 this.su_chPrev = this.su_ch2; 759 final int su_ch2Shadow = this.data.ll8[this.su_tPos] & 0xff; 760 this.su_ch2 = su_ch2Shadow; 761 this.su_tPos = this.data.tt[this.su_tPos]; 762 this.su_i2++; 763 this.currentState = NO_RAND_PART_B_STATE; 764 this.crc.updateCRC(su_ch2Shadow); 765 return su_ch2Shadow; 766 } 767 this.currentState = NO_RAND_PART_A_STATE; 768 endBlock(); 769 initBlock(); 770 return setupBlock(); 771 } 772 773 private int setupRandPartB() throws IOException { 774 if (this.su_ch2 != this.su_chPrev) { 775 this.currentState = RAND_PART_A_STATE; 776 this.su_count = 1; 777 return setupRandPartA(); 778 } else if (++this.su_count >= 4) { 779 this.su_z = (char) (this.data.ll8[this.su_tPos] & 0xff); 780 this.su_tPos = this.data.tt[this.su_tPos]; 781 if (this.su_rNToGo == 0) { 782 this.su_rNToGo = Rand.rNums(this.su_rTPos) - 1; 783 if (++this.su_rTPos == 512) { 784 this.su_rTPos = 0; 785 } 786 } else { 787 this.su_rNToGo--; 788 } 789 this.su_j2 = 0; 790 this.currentState = RAND_PART_C_STATE; 791 if (this.su_rNToGo == 1) { 792 this.su_z ^= 1; 793 } 794 return setupRandPartC(); 795 } else { 796 this.currentState = RAND_PART_A_STATE; 797 return setupRandPartA(); 798 } 799 } 800 801 private int setupRandPartC() throws IOException { 802 if (this.su_j2 < this.su_z) { 803 this.crc.updateCRC(this.su_ch2); 804 this.su_j2++; 805 return this.su_ch2; 806 } 807 this.currentState = RAND_PART_A_STATE; 808 this.su_i2++; 809 this.su_count = 0; 810 return setupRandPartA(); 811 } 812 813 private int setupNoRandPartB() throws IOException { 814 if (this.su_ch2 != this.su_chPrev) { 815 this.su_count = 1; 816 return setupNoRandPartA(); 817 } else if (++this.su_count >= 4) { 818 this.su_z = (char) (this.data.ll8[this.su_tPos] & 0xff); 819 this.su_tPos = this.data.tt[this.su_tPos]; 820 this.su_j2 = 0; 821 return setupNoRandPartC(); 822 } else { 823 return setupNoRandPartA(); 824 } 825 } 826 827 private int setupNoRandPartC() throws IOException { 828 if (this.su_j2 < this.su_z) { 829 final int su_ch2Shadow = this.su_ch2; 830 this.crc.updateCRC(su_ch2Shadow); 831 this.su_j2++; 832 this.currentState = NO_RAND_PART_C_STATE; 833 return su_ch2Shadow; 834 } 835 this.su_i2++; 836 this.su_count = 0; 837 return setupNoRandPartA(); 838 } 839 840 private static final class Data { 841 842 // (with blockSize 900k) 843 final boolean[] inUse = new boolean[256]; // 256 byte 844 845 final byte[] seqToUnseq = new byte[256]; // 256 byte 846 final byte[] selector = new byte[MAX_SELECTORS]; // 18002 byte 847 final byte[] selectorMtf = new byte[MAX_SELECTORS]; // 18002 byte 848 849 /** 850 * Freq table collected to save a pass over the data during 851 * decompression. 852 */ 853 final int[] unzftab = new int[256]; // 1024 byte 854 855 final int[][] limit = new int[N_GROUPS][MAX_ALPHA_SIZE]; // 6192 byte 856 final int[][] base = new int[N_GROUPS][MAX_ALPHA_SIZE]; // 6192 byte 857 final int[][] perm = new int[N_GROUPS][MAX_ALPHA_SIZE]; // 6192 byte 858 final int[] minLens = new int[N_GROUPS]; // 24 byte 859 860 final int[] cftab = new int[257]; // 1028 byte 861 final char[] getAndMoveToFrontDecode_yy = new char[256]; // 512 byte 862 final char[][] temp_charArray2d = new char[N_GROUPS][MAX_ALPHA_SIZE]; // 3096 863 // byte 864 final byte[] recvDecodingTables_pos = new byte[N_GROUPS]; // 6 byte 865 // --------------- 866 // 60798 byte 867 868 int[] tt; // 3600000 byte 869 byte[] ll8; // 900000 byte 870 871 // --------------- 872 // 4560782 byte 873 // =============== 874 875 Data(final int blockSize100k) { 876 this.ll8 = new byte[blockSize100k * BZip2Constants.BASEBLOCKSIZE]; 877 } 878 879 /** 880 * Initializes the {@link #tt} array. 881 * 882 * This method is called when the required length of the array is known. 883 * I don't initialize it at construction time to avoid unneccessary 884 * memory allocation when compressing small files. 885 */ 886 int[] initTT(final int length) { 887 int[] ttShadow = this.tt; 888 889 // tt.length should always be >= length, but theoretically 890 // it can happen, if the compressor mixed small and large 891 // blocks. Normally only the last block will be smaller 892 // than others. 893 if ((ttShadow == null) || (ttShadow.length < length)) { 894 this.tt = ttShadow = new int[length]; 895 } 896 897 return ttShadow; 898 } 899 900 } 901 902 /** 903 * Checks if the signature matches what is expected for a bzip2 file. 904 * 905 * @param signature 906 * the bytes to check 907 * @param length 908 * the number of bytes to check 909 * @return true, if this stream is a bzip2 compressed stream, false otherwise 910 * 911 * @since 1.1 912 */ 913 public static boolean matches(final byte[] signature, final int length) { 914 915 if (length < 3) { 916 return false; 917 } 918 919 if (signature[0] != 'B') { 920 return false; 921 } 922 923 if (signature[1] != 'Z') { 924 return false; 925 } 926 927 if (signature[2] != 'h') { 928 return false; 929 } 930 931 return true; 932 } 933}