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TMI-84: LZWDecoder fixes for > 12 bit exception when using full 12 bit (4096 entries) table

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Harald Kuhr
2014-12-04 16:51:37 +01:00
parent 9539e8e2e5
commit 27b2ff3745
4 changed files with 26 additions and 31 deletions
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imageio/imageio-tiff/src/main/java/com/twelvemonkeys/imageio/plugins/tiff/LZWDecoder.java
+20 -23
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@@ -33,12 +33,11 @@ import com.twelvemonkeys.io.enc.Decoder;
import java.io.IOException;
import java.io.InputStream;
import java.lang.String;
import java.nio.ByteBuffer;
/**
* Lempel–Ziv–Welch (LZW) decompression. LZW is a universal loss-less data compression algorithm
* created by Abraham Lempel, Jacob Ziv, and Terry Welch.
* Lempel–Ziv–Welch (LZW) decompression.
* LZW is a universal loss-less data compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch.
* Inspired by libTiff's LZW decompression.
*
* @author <a href="mailto:harald.kuhr@gmail.com">Harald Kuhr</a>
@@ -57,8 +56,6 @@ abstract class LZWDecoder implements Decoder {
private static final int TABLE_SIZE = 1 << MAX_BITS;
private final boolean compatibilityMode;
private final LZWString[] table;
private int tableLength;
int bitsPerCode;
@@ -70,11 +67,8 @@ abstract class LZWDecoder implements Decoder {
int nextData;
int nextBits;
protected LZWDecoder(final boolean compatibilityMode) {
this.compatibilityMode = compatibilityMode;
table = new LZWString[compatibilityMode ? TABLE_SIZE + 1024 : TABLE_SIZE]; // libTiff adds 1024 "for compatibility"...
protected LZWDecoder(int tableSize) {
table = new LZWString[tableSize];
// First 258 entries of table is always fixed
for (int i = 0; i < 256; i++) {
@@ -97,6 +91,10 @@ abstract class LZWDecoder implements Decoder {
}
public int decode(final InputStream stream, final ByteBuffer buffer) throws IOException {
if (buffer == null) {
throw new NullPointerException("buffer == null"); // As per contract
}
// Adapted from the pseudo-code example found in the TIFF 6.0 Specification, 1992.
// See Section 13: "LZW Compression"/"LZW Decoding", page 61+
int code;
@@ -114,8 +112,7 @@ abstract class LZWDecoder implements Decoder {
}
else {
if (table[oldCode] == null) {
System.err.println("tableLength: " + tableLength);
System.err.println("oldCode: " + oldCode);
throw new DecodeException(String.format("Corrupted TIFF LZW: code %d (table size: %d)", oldCode, tableLength));
}
if (isInTable(code)) {
@@ -133,7 +130,7 @@ abstract class LZWDecoder implements Decoder {
oldCode = code;
if (buffer.remaining() < maxString + 1) {
// Buffer full, stop decoding for now
// Buffer (almost) full, stop decoding for now
break;
}
}
@@ -142,18 +139,18 @@ abstract class LZWDecoder implements Decoder {
}
private void addStringToTable(final LZWString string) throws IOException {
if (tableLength > table.length) {
throw new DecodeException(String.format("TIFF LZW with more than %d bits per code encountered (table overflow)", MAX_BITS));
}
table[tableLength++] = string;
if (tableLength > maxCode) {
bitsPerCode++;
if (bitsPerCode > MAX_BITS) {
if (compatibilityMode) {
bitsPerCode--;
}
else {
throw new DecodeException(String.format("TIFF LZW with more than %d bits per code encountered (table overflow)", MAX_BITS));
}
// Continue reading MAX_BITS (12 bit) length codes
bitsPerCode = MAX_BITS;
}
bitMask = bitmaskFor(bitsPerCode);
@@ -173,9 +170,9 @@ abstract class LZWDecoder implements Decoder {
protected abstract int getNextCode(final InputStream stream) throws IOException;
static boolean isOldBitReversedStream(final InputStream stream) throws IOException {
stream.mark(2);
try {
int one = stream.read();
int two = stream.read();
@@ -191,10 +188,10 @@ abstract class LZWDecoder implements Decoder {
return oldBitReversedStream ? new LZWCompatibilityDecoder() : new LZWSpecDecoder();
}
private static final class LZWSpecDecoder extends LZWDecoder {
static final class LZWSpecDecoder extends LZWDecoder {
protected LZWSpecDecoder() {
super(false);
super(TABLE_SIZE);
}
@Override
@@ -243,7 +240,7 @@ abstract class LZWDecoder implements Decoder {
// compressed data will be identical whether it is an ‘II’ or ‘MM’ file."
protected LZWCompatibilityDecoder() {
super(true);
super(TABLE_SIZE + 1024); // libTiff adds 1024 "for compatibility", this value seems to work fine...
}
@Override