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Apache Commons Compress software defines an API for working with
compression and archive formats. These include: bzip2, gzip, pack200,
lzma, xz, Snappy, traditional Unix Compress, DEFLATE, DEFLATE64, LZ4,
Brotli, Zstandard and ar, cpio, jar, tar, zip, dump, 7z, arj.
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
/*
* This package is based on the work done by Keiron Liddle, Aftex Software
* to whom the Ant project is very grateful for his
* great code.
*/
package org.apache.commons.compress.compressors.bzip2;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteOrder;
import java.util.Arrays;
import org.apache.commons.compress.compressors.CompressorInputStream;
import org.apache.commons.compress.utils.BitInputStream;
import org.apache.commons.compress.utils.CloseShieldFilterInputStream;
import org.apache.commons.compress.utils.InputStreamStatistics;
/**
* An input stream that decompresses from the BZip2 format to be read as any other stream.
*
* @NotThreadSafe
*/
public class BZip2CompressorInputStream extends CompressorInputStream
implements BZip2Constants, InputStreamStatistics {
/**
* Index of the last char in the block, so the block size == last + 1.
*/
private int last;
/**
* Index in zptr[] of original string after sorting.
*/
private int origPtr;
/**
* always: in the range 0 .. 9. The current block size is 100000 * this
* number.
*/
private int blockSize100k;
private boolean blockRandomised;
private final CRC crc = new CRC();
private int nInUse;
private BitInputStream bin;
private final boolean decompressConcatenated;
private static final int EOF = 0;
private static final int START_BLOCK_STATE = 1;
private static final int RAND_PART_A_STATE = 2;
private static final int RAND_PART_B_STATE = 3;
private static final int RAND_PART_C_STATE = 4;
private static final int NO_RAND_PART_A_STATE = 5;
private static final int NO_RAND_PART_B_STATE = 6;
private static final int NO_RAND_PART_C_STATE = 7;
private int currentState = START_BLOCK_STATE;
private int storedBlockCRC, storedCombinedCRC;
private int computedBlockCRC, computedCombinedCRC;
// Variables used by setup* methods exclusively
private int su_count;
private int su_ch2;
private int su_chPrev;
private int su_i2;
private int su_j2;
private int su_rNToGo;
private int su_rTPos;
private int su_tPos;
private char su_z;
/**
* All memory intensive stuff. This field is initialized by initBlock().
*/
private BZip2CompressorInputStream.Data data;
/**
* Constructs a new BZip2CompressorInputStream which decompresses bytes
* read from the specified stream. This doesn't support decompressing
* concatenated .bz2 files.
*
* @param in the InputStream from which this object should be created
* @throws IOException
* if the stream content is malformed or an I/O error occurs.
* @throws NullPointerException
* if {@code in == null}
*/
public BZip2CompressorInputStream(final InputStream in) throws IOException {
this(in, false);
}
/**
* Constructs a new BZip2CompressorInputStream which decompresses bytes
* read from the specified stream.
*
* @param in the InputStream from which this object should be created
* @param decompressConcatenated
* if true, decompress until the end of the input;
* if false, stop after the first .bz2 stream and
* leave the input position to point to the next
* byte after the .bz2 stream
*
* @throws IOException
* if {@code in == null}, the stream content is malformed, or an I/O error occurs.
*/
public BZip2CompressorInputStream(final InputStream in, final boolean decompressConcatenated) throws IOException {
this.bin = new BitInputStream(in == System.in ? new CloseShieldFilterInputStream(in) : in,
ByteOrder.BIG_ENDIAN);
this.decompressConcatenated = decompressConcatenated;
init(true);
initBlock();
}
@Override
public int read() throws IOException {
if (this.bin != null) {
final int r = read0();
count(r < 0 ? -1 : 1);
return r;
}
throw new IOException("Stream closed");
}
/*
* (non-Javadoc)
*
* @see java.io.InputStream#read(byte[], int, int)
*/
@Override
public int read(final byte[] dest, final int offs, final int len)
throws IOException {
if (offs < 0) {
throw new IndexOutOfBoundsException("offs(" + offs + ") < 0.");
}
if (len < 0) {
throw new IndexOutOfBoundsException("len(" + len + ") < 0.");
}
if (offs + len > dest.length) {
throw new IndexOutOfBoundsException("offs(" + offs + ") + len("
+ len + ") > dest.length(" + dest.length + ").");
}
if (this.bin == null) {
throw new IOException("Stream closed");
}
if (len == 0) {
return 0;
}
final int hi = offs + len;
int destOffs = offs;
int b;
while (destOffs < hi && ((b = read0()) >= 0)) {
dest[destOffs++] = (byte) b;
count(1);
}
return (destOffs == offs) ? -1 : (destOffs - offs);
}
/**
* @since 1.17
*/
@Override
public long getCompressedCount() {
return bin.getBytesRead();
}
private void makeMaps() {
final boolean[] inUse = this.data.inUse;
final byte[] seqToUnseq = this.data.seqToUnseq;
int nInUseShadow = 0;
for (int i = 0; i < 256; i++) {
if (inUse[i]) {
seqToUnseq[nInUseShadow++] = (byte) i;
}
}
this.nInUse = nInUseShadow;
}
private int read0() throws IOException {
switch (currentState) {
case EOF:
return -1;
case START_BLOCK_STATE:
return setupBlock();
case RAND_PART_A_STATE:
throw new IllegalStateException();
case RAND_PART_B_STATE:
return setupRandPartB();
case RAND_PART_C_STATE:
return setupRandPartC();
case NO_RAND_PART_A_STATE:
throw new IllegalStateException();
case NO_RAND_PART_B_STATE:
return setupNoRandPartB();
case NO_RAND_PART_C_STATE:
return setupNoRandPartC();
default:
throw new IllegalStateException();
}
}
private int readNextByte(final BitInputStream in) throws IOException {
final long b = in.readBits(8);
return (int) b;
}
private boolean init(final boolean isFirstStream) throws IOException {
if (null == bin) {
throw new IOException("No InputStream");
}
if (!isFirstStream) {
bin.clearBitCache();
}
final int magic0 = readNextByte(this.bin);
if (magic0 == -1 && !isFirstStream) {
return false;
}
final int magic1 = readNextByte(this.bin);
final int magic2 = readNextByte(this.bin);
if (magic0 != 'B' || magic1 != 'Z' || magic2 != 'h') {
throw new IOException(isFirstStream
? "Stream is not in the BZip2 format"
: "Garbage after a valid BZip2 stream");
}
final int blockSize = readNextByte(this.bin);
if ((blockSize < '1') || (blockSize > '9')) {
throw new IOException("BZip2 block size is invalid");
}
this.blockSize100k = blockSize - '0';
this.computedCombinedCRC = 0;
return true;
}
private void initBlock() throws IOException {
final BitInputStream bin = this.bin;
char magic0;
char magic1;
char magic2;
char magic3;
char magic4;
char magic5;
while (true) {
// Get the block magic bytes.
magic0 = bsGetUByte(bin);
magic1 = bsGetUByte(bin);
magic2 = bsGetUByte(bin);
magic3 = bsGetUByte(bin);
magic4 = bsGetUByte(bin);
magic5 = bsGetUByte(bin);
// If isn't end of stream magic, break out of the loop.
if (magic0 != 0x17 || magic1 != 0x72 || magic2 != 0x45
|| magic3 != 0x38 || magic4 != 0x50 || magic5 != 0x90) {
break;
}
// End of stream was reached. Check the combined CRC and
// advance to the next .bz2 stream if decoding concatenated
// streams.
if (complete()) {
return;
}
}
if (magic0 != 0x31 || // '1'
magic1 != 0x41 || // ')'
magic2 != 0x59 || // 'Y'
magic3 != 0x26 || // '&'
magic4 != 0x53 || // 'S'
magic5 != 0x59 // 'Y'
) {
this.currentState = EOF;
throw new IOException("Bad block header");
}
this.storedBlockCRC = bsGetInt(bin);
this.blockRandomised = bsR(bin, 1) == 1;
/*
* Allocate data here instead in constructor, so we do not allocate
* it if the input file is empty.
*/
if (this.data == null) {
this.data = new Data(this.blockSize100k);
}
// currBlockNo++;
getAndMoveToFrontDecode();
this.crc.initializeCRC();
this.currentState = START_BLOCK_STATE;
}
private void endBlock() throws IOException {
this.computedBlockCRC = this.crc.getFinalCRC();
// A bad CRC is considered a fatal error.
if (this.storedBlockCRC != this.computedBlockCRC) {
// make next blocks readable without error
// (repair feature, not yet documented, not tested)
this.computedCombinedCRC = (this.storedCombinedCRC << 1)
| (this.storedCombinedCRC >>> 31);
this.computedCombinedCRC ^= this.storedBlockCRC;
throw new IOException("BZip2 CRC error");
}
this.computedCombinedCRC = (this.computedCombinedCRC << 1)
| (this.computedCombinedCRC >>> 31);
this.computedCombinedCRC ^= this.computedBlockCRC;
}
private boolean complete() throws IOException {
this.storedCombinedCRC = bsGetInt(bin);
this.currentState = EOF;
this.data = null;
if (this.storedCombinedCRC != this.computedCombinedCRC) {
throw new IOException("BZip2 CRC error");
}
// Look for the next .bz2 stream if decompressing
// concatenated files.
return !decompressConcatenated || !init(false);
}
@Override
public void close() throws IOException {
final BitInputStream inShadow = this.bin;
if (inShadow != null) {
try {
inShadow.close();
} finally {
this.data = null;
this.bin = null;
}
}
}
/**
* read bits from the input stream
* @param n the number of bits to read, must not exceed 32?
* @return the requested bits combined into an int
* @throws IOException
*/
private static int bsR(final BitInputStream bin, final int n) throws IOException {
final long thech = bin.readBits(n);
if (thech < 0) {
throw new IOException("Unexpected end of stream");
}
return (int) thech;
}
private static boolean bsGetBit(final BitInputStream bin) throws IOException {
return bsR(bin, 1) != 0;
}
private static char bsGetUByte(final BitInputStream bin) throws IOException {
return (char) bsR(bin, 8);
}
private static int bsGetInt(final BitInputStream bin) throws IOException {
return bsR(bin, 32);
}
private static void checkBounds(final int checkVal, final int limitExclusive, final String name)
throws IOException {
if (checkVal < 0) {
throw new IOException("Corrupted input, " + name + " value negative");
}
if (checkVal >= limitExclusive) {
throw new IOException("Corrupted input, " + name + " value too big");
}
}
/**
* Called by createHuffmanDecodingTables() exclusively.
*/
private static void hbCreateDecodeTables(final int[] limit,
final int[] base, final int[] perm, final char[] length,
final int minLen, final int maxLen, final int alphaSize)
throws IOException {
for (int i = minLen, pp = 0; i <= maxLen; i++) {
for (int j = 0; j < alphaSize; j++) {
if (length[j] == i) {
perm[pp++] = j;
}
}
}
for (int i = MAX_CODE_LEN; --i > 0;) {
base[i] = 0;
limit[i] = 0;
}
for (int i = 0; i < alphaSize; i++) {
final int l = length[i];
checkBounds(l, MAX_ALPHA_SIZE, "length");
base[l + 1]++;
}
for (int i = 1, b = base[0]; i < MAX_CODE_LEN; i++) {
b += base[i];
base[i] = b;
}
for (int i = minLen, vec = 0, b = base[i]; i <= maxLen; i++) {
final int nb = base[i + 1];
vec += nb - b;
b = nb;
limit[i] = vec - 1;
vec <<= 1;
}
for (int i = minLen + 1; i <= maxLen; i++) {
base[i] = ((limit[i - 1] + 1) << 1) - base[i];
}
}
private void recvDecodingTables() throws IOException {
final BitInputStream bin = this.bin;
final Data dataShadow = this.data;
final boolean[] inUse = dataShadow.inUse;
final byte[] pos = dataShadow.recvDecodingTables_pos;
final byte[] selector = dataShadow.selector;
final byte[] selectorMtf = dataShadow.selectorMtf;
int inUse16 = 0;
/* Receive the mapping table */
for (int i = 0; i < 16; i++) {
if (bsGetBit(bin)) {
inUse16 |= 1 << i;
}
}
Arrays.fill(inUse, false);
for (int i = 0; i < 16; i++) {
if ((inUse16 & (1 << i)) != 0) {
final int i16 = i << 4;
for (int j = 0; j < 16; j++) {
if (bsGetBit(bin)) {
inUse[i16 + j] = true;
}
}
}
}
makeMaps();
final int alphaSize = this.nInUse + 2;
/* Now the selectors */
final int nGroups = bsR(bin, 3);
final int selectors = bsR(bin, 15);
if (selectors < 0) {
throw new IOException("Corrupted input, nSelectors value negative");
}
checkBounds(alphaSize, MAX_ALPHA_SIZE + 1, "alphaSize");
checkBounds(nGroups, N_GROUPS + 1, "nGroups");
// Don't fail on nSelectors overflowing boundaries but discard the values in overflow
// See https://gnu.wildebeest.org/blog/mjw/2019/08/02/bzip2-and-the-cve-that-wasnt/
// and https://sourceware.org/ml/bzip2-devel/2019-q3/msg00007.html
for (int i = 0; i < selectors; i++) {
int j = 0;
while (bsGetBit(bin)) {
j++;
}
if (i < MAX_SELECTORS) {
selectorMtf[i] = (byte) j;
}
}
final int nSelectors = selectors > MAX_SELECTORS ? MAX_SELECTORS : selectors;
/* Undo the MTF values for the selectors. */
for (int v = nGroups; --v >= 0;) {
pos[v] = (byte) v;
}
for (int i = 0; i < nSelectors; i++) {
int v = selectorMtf[i] & 0xff;
checkBounds(v, N_GROUPS, "selectorMtf");
final byte tmp = pos[v];
while (v > 0) {
// nearly all times v is zero, 4 in most other cases
pos[v] = pos[v - 1];
v--;
}
pos[0] = tmp;
selector[i] = tmp;
}
final char[][] len = dataShadow.temp_charArray2d;
/* Now the coding tables */
for (int t = 0; t < nGroups; t++) {
int curr = bsR(bin, 5);
final char[] len_t = len[t];
for (int i = 0; i < alphaSize; i++) {
while (bsGetBit(bin)) {
curr += bsGetBit(bin) ? -1 : 1;
}
len_t[i] = (char) curr;
}
}
// finally create the Huffman tables
createHuffmanDecodingTables(alphaSize, nGroups);
}
/**
* Called by recvDecodingTables() exclusively.
*/
private void createHuffmanDecodingTables(final int alphaSize,
final int nGroups) throws IOException {
final Data dataShadow = this.data;
final char[][] len = dataShadow.temp_charArray2d;
final int[] minLens = dataShadow.minLens;
final int[][] limit = dataShadow.limit;
final int[][] base = dataShadow.base;
final int[][] perm = dataShadow.perm;
for (int t = 0; t < nGroups; t++) {
int minLen = 32;
int maxLen = 0;
final char[] len_t = len[t];
for (int i = alphaSize; --i >= 0;) {
final char lent = len_t[i];
if (lent > maxLen) {
maxLen = lent;
}
if (lent < minLen) {
minLen = lent;
}
}
hbCreateDecodeTables(limit[t], base[t], perm[t], len[t], minLen,
maxLen, alphaSize);
minLens[t] = minLen;
}
}
private void getAndMoveToFrontDecode() throws IOException {
final BitInputStream bin = this.bin;
this.origPtr = bsR(bin, 24);
recvDecodingTables();
final Data dataShadow = this.data;
final byte[] ll8 = dataShadow.ll8;
final int[] unzftab = dataShadow.unzftab;
final byte[] selector = dataShadow.selector;
final byte[] seqToUnseq = dataShadow.seqToUnseq;
final char[] yy = dataShadow.getAndMoveToFrontDecode_yy;
final int[] minLens = dataShadow.minLens;
final int[][] limit = dataShadow.limit;
final int[][] base = dataShadow.base;
final int[][] perm = dataShadow.perm;
final int limitLast = this.blockSize100k * 100000;
/*
* Setting up the unzftab entries here is not strictly necessary, but it
* does save having to do it later in a separate pass, and so saves a
* block's worth of cache misses.
*/
for (int i = 256; --i >= 0;) {
yy[i] = (char) i;
unzftab[i] = 0;
}
int groupNo = 0;
int groupPos = G_SIZE - 1;
final int eob = this.nInUse + 1;
int nextSym = getAndMoveToFrontDecode0();
int lastShadow = -1;
int zt = selector[groupNo] & 0xff;
checkBounds(zt, N_GROUPS, "zt");
int[] base_zt = base[zt];
int[] limit_zt = limit[zt];
int[] perm_zt = perm[zt];
int minLens_zt = minLens[zt];
while (nextSym != eob) {
if ((nextSym == RUNA) || (nextSym == RUNB)) {
int s = -1;
for (int n = 1; true; n <<= 1) {
if (nextSym == RUNA) {
s += n;
} else if (nextSym == RUNB) {
s += n << 1;
} else {
break;
}
if (groupPos == 0) {
groupPos = G_SIZE - 1;
checkBounds(++groupNo, MAX_SELECTORS, "groupNo");
zt = selector[groupNo] & 0xff;
checkBounds(zt, N_GROUPS, "zt");
base_zt = base[zt];
limit_zt = limit[zt];
perm_zt = perm[zt];
minLens_zt = minLens[zt];
} else {
groupPos--;
}
int zn = minLens_zt;
checkBounds(zn, MAX_ALPHA_SIZE, "zn");
int zvec = bsR(bin, zn);
while(zvec > limit_zt[zn]) {
checkBounds(++zn, MAX_ALPHA_SIZE, "zn");
zvec = (zvec << 1) | bsR(bin, 1);
}
final int tmp = zvec - base_zt[zn];
checkBounds(tmp, MAX_ALPHA_SIZE, "zvec");
nextSym = perm_zt[tmp];
}
checkBounds(s, this.data.ll8.length, "s");
final int yy0 = yy[0];
checkBounds(yy0, 256, "yy");
final byte ch = seqToUnseq[yy0];
unzftab[ch & 0xff] += s + 1;
final int from = ++lastShadow;
lastShadow += s;
checkBounds(lastShadow, this.data.ll8.length, "lastShadow");
Arrays.fill(ll8, from, lastShadow + 1, ch);
if (lastShadow >= limitLast) {
throw new IOException("Block overrun while expanding RLE in MTF, "
+ lastShadow + " exceeds " + limitLast);
}
} else {
if (++lastShadow >= limitLast) {
throw new IOException("Block overrun in MTF, "
+ lastShadow + " exceeds " + limitLast);
}
checkBounds(nextSym, 256 + 1, "nextSym");
final char tmp = yy[nextSym - 1];
checkBounds(tmp, 256, "yy");
unzftab[seqToUnseq[tmp] & 0xff]++;
ll8[lastShadow] = seqToUnseq[tmp];
/*
* This loop is hammered during decompression, hence avoid
* native method call overhead of System.arraycopy for very
* small ranges to copy.
*/
if (nextSym <= 16) {
for (int j = nextSym - 1; j > 0;) {
yy[j] = yy[--j];
}
} else {
System.arraycopy(yy, 0, yy, 1, nextSym - 1);
}
yy[0] = tmp;
if (groupPos == 0) {
groupPos = G_SIZE - 1;
checkBounds(++groupNo, MAX_SELECTORS, "groupNo");
zt = selector[groupNo] & 0xff;
checkBounds(zt, N_GROUPS, "zt");
base_zt = base[zt];
limit_zt = limit[zt];
perm_zt = perm[zt];
minLens_zt = minLens[zt];
} else {
groupPos--;
}
int zn = minLens_zt;
checkBounds(zn, MAX_ALPHA_SIZE, "zn");
int zvec = bsR(bin, zn);
while(zvec > limit_zt[zn]) {
checkBounds(++zn, MAX_ALPHA_SIZE, "zn");
zvec = (zvec << 1) | bsR(bin, 1);
}
final int idx = zvec - base_zt[zn];
checkBounds(idx, MAX_ALPHA_SIZE, "zvec");
nextSym = perm_zt[idx];
}
}
this.last = lastShadow;
}
private int getAndMoveToFrontDecode0() throws IOException {
final Data dataShadow = this.data;
final int zt = dataShadow.selector[0] & 0xff;
checkBounds(zt, N_GROUPS, "zt");
final int[] limit_zt = dataShadow.limit[zt];
int zn = dataShadow.minLens[zt];
checkBounds(zn, MAX_ALPHA_SIZE, "zn");
int zvec = bsR(bin, zn);
while (zvec > limit_zt[zn]) {
checkBounds(++zn, MAX_ALPHA_SIZE, "zn");
zvec = (zvec << 1) | bsR(bin, 1);
}
final int tmp = zvec - dataShadow.base[zt][zn];
checkBounds(tmp, MAX_ALPHA_SIZE, "zvec");
return dataShadow.perm[zt][tmp];
}
private int setupBlock() throws IOException {
if (currentState == EOF || this.data == null) {
return -1;
}
final int[] cftab = this.data.cftab;
final int ttLen = this.last + 1;
final int[] tt = this.data.initTT(ttLen);
final byte[] ll8 = this.data.ll8;
cftab[0] = 0;
System.arraycopy(this.data.unzftab, 0, cftab, 1, 256);
for (int i = 1, c = cftab[0]; i <= 256; i++) {
c += cftab[i];
cftab[i] = c;
}
for (int i = 0, lastShadow = this.last; i <= lastShadow; i++) {
final int tmp = cftab[ll8[i] & 0xff]++;
checkBounds(tmp, ttLen, "tt index");
tt[tmp] = i;
}
if ((this.origPtr < 0) || (this.origPtr >= tt.length)) {
throw new IOException("Stream corrupted");
}
this.su_tPos = tt[this.origPtr];
this.su_count = 0;
this.su_i2 = 0;
this.su_ch2 = 256; /* not a char and not EOF */
if (this.blockRandomised) {
this.su_rNToGo = 0;
this.su_rTPos = 0;
return setupRandPartA();
}
return setupNoRandPartA();
}
private int setupRandPartA() throws IOException {
if (this.su_i2 <= this.last) {
this.su_chPrev = this.su_ch2;
int su_ch2Shadow = this.data.ll8[this.su_tPos] & 0xff;
checkBounds(this.su_tPos, this.data.tt.length, "su_tPos");
this.su_tPos = this.data.tt[this.su_tPos];
if (this.su_rNToGo == 0) {
this.su_rNToGo = Rand.rNums(this.su_rTPos) - 1;
if (++this.su_rTPos == 512) {
this.su_rTPos = 0;
}
} else {
this.su_rNToGo--;
}
this.su_ch2 = su_ch2Shadow ^= (this.su_rNToGo == 1) ? 1 : 0;
this.su_i2++;
this.currentState = RAND_PART_B_STATE;
this.crc.updateCRC(su_ch2Shadow);
return su_ch2Shadow;
}
endBlock();
initBlock();
return setupBlock();
}
private int setupNoRandPartA() throws IOException {
if (this.su_i2 <= this.last) {
this.su_chPrev = this.su_ch2;
final int su_ch2Shadow = this.data.ll8[this.su_tPos] & 0xff;
this.su_ch2 = su_ch2Shadow;
checkBounds(this.su_tPos, this.data.tt.length, "su_tPos");
this.su_tPos = this.data.tt[this.su_tPos];
this.su_i2++;
this.currentState = NO_RAND_PART_B_STATE;
this.crc.updateCRC(su_ch2Shadow);
return su_ch2Shadow;
}
this.currentState = NO_RAND_PART_A_STATE;
endBlock();
initBlock();
return setupBlock();
}
private int setupRandPartB() throws IOException {
if (this.su_ch2 != this.su_chPrev) {
this.currentState = RAND_PART_A_STATE;
this.su_count = 1;
return setupRandPartA();
}
if (++this.su_count < 4) {
this.currentState = RAND_PART_A_STATE;
return setupRandPartA();
}
this.su_z = (char) (this.data.ll8[this.su_tPos] & 0xff);
checkBounds(this.su_tPos, this.data.tt.length, "su_tPos");
this.su_tPos = this.data.tt[this.su_tPos];
if (this.su_rNToGo == 0) {
this.su_rNToGo = Rand.rNums(this.su_rTPos) - 1;
if (++this.su_rTPos == 512) {
this.su_rTPos = 0;
}
} else {
this.su_rNToGo--;
}
this.su_j2 = 0;
this.currentState = RAND_PART_C_STATE;
if (this.su_rNToGo == 1) {
this.su_z ^= 1;
}
return setupRandPartC();
}
private int setupRandPartC() throws IOException {
if (this.su_j2 < this.su_z) {
this.crc.updateCRC(this.su_ch2);
this.su_j2++;
return this.su_ch2;
}
this.currentState = RAND_PART_A_STATE;
this.su_i2++;
this.su_count = 0;
return setupRandPartA();
}
private int setupNoRandPartB() throws IOException {
if (this.su_ch2 != this.su_chPrev) {
this.su_count = 1;
return setupNoRandPartA();
}
if (++this.su_count >= 4) {
checkBounds(this.su_tPos, this.data.ll8.length, "su_tPos");
this.su_z = (char) (this.data.ll8[this.su_tPos] & 0xff);
this.su_tPos = this.data.tt[this.su_tPos];
this.su_j2 = 0;
return setupNoRandPartC();
}
return setupNoRandPartA();
}
private int setupNoRandPartC() throws IOException {
if (this.su_j2 < this.su_z) {
final int su_ch2Shadow = this.su_ch2;
this.crc.updateCRC(su_ch2Shadow);
this.su_j2++;
this.currentState = NO_RAND_PART_C_STATE;
return su_ch2Shadow;
}
this.su_i2++;
this.su_count = 0;
return setupNoRandPartA();
}
private static final class Data {
// (with blockSize 900k)
final boolean[] inUse = new boolean[256]; // 256 byte
final byte[] seqToUnseq = new byte[256]; // 256 byte
final byte[] selector = new byte[MAX_SELECTORS]; // 18002 byte
final byte[] selectorMtf = new byte[MAX_SELECTORS]; // 18002 byte
/**
* Freq table collected to save a pass over the data during
* decompression.
*/
final int[] unzftab = new int[256]; // 1024 byte
final int[][] limit = new int[N_GROUPS][MAX_ALPHA_SIZE]; // 6192 byte
final int[][] base = new int[N_GROUPS][MAX_ALPHA_SIZE]; // 6192 byte
final int[][] perm = new int[N_GROUPS][MAX_ALPHA_SIZE]; // 6192 byte
final int[] minLens = new int[N_GROUPS]; // 24 byte
final int[] cftab = new int[257]; // 1028 byte
final char[] getAndMoveToFrontDecode_yy = new char[256]; // 512 byte
final char[][] temp_charArray2d = new char[N_GROUPS][MAX_ALPHA_SIZE]; // 3096
// byte
final byte[] recvDecodingTables_pos = new byte[N_GROUPS]; // 6 byte
// ---------------
// 60798 byte
int[] tt; // 3600000 byte
final byte[] ll8; // 900000 byte
// ---------------
// 4560782 byte
// ===============
Data(final int blockSize100k) {
this.ll8 = new byte[blockSize100k * BZip2Constants.BASEBLOCKSIZE];
}
/**
* Initializes the {@link #tt} array.
*
* This method is called when the required length of the array is known.
* I don't initialize it at construction time to avoid unnecessary
* memory allocation when compressing small files.
*/
int[] initTT(final int length) {
int[] ttShadow = this.tt;
// tt.length should always be >= length, but theoretically
// it can happen, if the compressor mixed small and large
// blocks. Normally only the last block will be smaller
// than others.
if ((ttShadow == null) || (ttShadow.length < length)) {
this.tt = ttShadow = new int[length];
}
return ttShadow;
}
}
/**
* Checks if the signature matches what is expected for a bzip2 file.
*
* @param signature
* the bytes to check
* @param length
* the number of bytes to check
* @return true, if this stream is a bzip2 compressed stream, false otherwise
*
* @since 1.1
*/
public static boolean matches(final byte[] signature, final int length) {
return length >= 3 && signature[0] == 'B' &&
signature[1] == 'Z' && signature[2] == 'h';
}
}