/*
* SingleXZInputStream
*
* Author: Lasse Collin <lasse.collin@tukaani.org>
*
* This file has been put into the public domain.
* You can do whatever you want with this file.
*/
package org.tukaani.xz;
import java.io.InputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.EOFException;
import org.tukaani.xz.common.DecoderUtil;
import org.tukaani.xz.common.StreamFlags;
import org.tukaani.xz.index.IndexHash;
import org.tukaani.xz.check.Check;
/**
* Decompresses exactly one XZ Stream in streamed mode (no seeking).
* The decompression stops after the first XZ Stream has been decompressed,
* and the read position in the input stream is left at the first byte
* after the end of the XZ Stream. This can be useful when XZ data has
* been stored inside some other file format or protocol.
* <p>
* Unless you know what you are doing, don't use this class to decompress
* standalone .xz files. For that purpose, use <code>XZInputStream</code>.
*
* <h4>When uncompressed size is known beforehand</h4>
* <p>
* If you are decompressing complete XZ streams and your application knows
* exactly how much uncompressed data there should be, it is good to try
* reading one more byte by calling <code>read()</code> and checking
* that it returns <code>-1</code>. This way the decompressor will parse the
* file footers and verify the integrity checks, giving the caller more
* confidence that the uncompressed data is valid.
*
* @see XZInputStream
*/
public class SingleXZInputStream extends InputStream {
private InputStream in;
private final int memoryLimit;
private final StreamFlags streamHeaderFlags;
private final Check check;
private final boolean verifyCheck;
private BlockInputStream blockDecoder = null;
private final IndexHash indexHash = new IndexHash();
private boolean endReached = false;
private IOException exception = null;
private final byte[] tempBuf = new byte[1];
/**
* Reads the Stream Header into a buffer.
* This is a helper function for the constructors.
*/
private static byte[] readStreamHeader(InputStream in) throws IOException {
byte[] streamHeader = new byte[DecoderUtil.STREAM_HEADER_SIZE];
new DataInputStream(in).readFully(streamHeader);
return streamHeader;
}
/**
* Creates a new XZ decompressor that decompresses exactly one
* XZ Stream from <code>in</code> without a memory usage limit.
* <p>
* This constructor reads and parses the XZ Stream Header (12 bytes)
* from <code>in</code>. The header of the first Block is not read
* until <code>read</code> is called.
*
* @param in input stream from which XZ-compressed
* data is read
*
* @throws XZFormatException
* input is not in the XZ format
*
* @throws CorruptedInputException
* XZ header CRC32 doesn't match
*
* @throws UnsupportedOptionsException
* XZ header is valid but specifies options
* not supported by this implementation
*
* @throws EOFException
* less than 12 bytes of input was available
* from <code>in</code>
*
* @throws IOException may be thrown by <code>in</code>
*/
public SingleXZInputStream(InputStream in) throws IOException {
this(in, -1);
}
/**
* Creates a new XZ decompressor that decompresses exactly one
* XZ Stream from <code>in</code> with an optional memory usage limit.
* <p>
* This is identical to <code>SingleXZInputStream(InputStream)</code>
* except that this takes also the <code>memoryLimit</code> argument.
*
* @param in input stream from which XZ-compressed
* data is read
*
* @param memoryLimit memory usage limit in kibibytes (KiB)
* or <code>-1</code> to impose no
* memory usage limit
*
* @throws XZFormatException
* input is not in the XZ format
*
* @throws CorruptedInputException
* XZ header CRC32 doesn't match
*
* @throws UnsupportedOptionsException
* XZ header is valid but specifies options
* not supported by this implementation
*
* @throws EOFException
* less than 12 bytes of input was available
* from <code>in</code>
*
* @throws IOException may be thrown by <code>in</code>
*/
public SingleXZInputStream(InputStream in, int memoryLimit)
throws IOException {
this(in, memoryLimit, true, readStreamHeader(in));
}
/**
* Creates a new XZ decompressor that decompresses exactly one
* XZ Stream from <code>in</code> with an optional memory usage limit
* and ability to disable verification of integrity checks.
* <p>
* This is identical to <code>SingleXZInputStream(InputStream,int)</code>
* except that this takes also the <code>verifyCheck</code> argument.
* <p>
* Note that integrity check verification should almost never be disabled.
* Possible reasons to disable integrity check verification:
* <ul>
* <li>Trying to recover data from a corrupt .xz file.</li>
* <li>Speeding up decompression. This matters mostly with SHA-256
* or with files that have compressed extremely well. It's recommended
* that integrity checking isn't disabled for performance reasons
* unless the file integrity is verified externally in some other
* way.</li>
* </ul>
* <p>
* <code>verifyCheck</code> only affects the integrity check of
* the actual compressed data. The CRC32 fields in the headers
* are always verified.
*
* @param in input stream from which XZ-compressed
* data is read
*
* @param memoryLimit memory usage limit in kibibytes (KiB)
* or <code>-1</code> to impose no
* memory usage limit
*
* @param verifyCheck if <code>true</code>, the integrity checks
* will be verified; this should almost never
* be set to <code>false</code>
*
* @throws XZFormatException
* input is not in the XZ format
*
* @throws CorruptedInputException
* XZ header CRC32 doesn't match
*
* @throws UnsupportedOptionsException
* XZ header is valid but specifies options
* not supported by this implementation
*
* @throws EOFException
* less than 12 bytes of input was available
* from <code>in</code>
*
* @throws IOException may be thrown by <code>in</code>
*
* @since 1.6
*/
public SingleXZInputStream(InputStream in, int memoryLimit,
boolean verifyCheck) throws IOException {
this(in, memoryLimit, verifyCheck, readStreamHeader(in));
}
SingleXZInputStream(InputStream in, int memoryLimit, boolean verifyCheck,
byte[] streamHeader) throws IOException {
this.in = in;
this.memoryLimit = memoryLimit;
this.verifyCheck = verifyCheck;
streamHeaderFlags = DecoderUtil.decodeStreamHeader(streamHeader);
check = Check.getInstance(streamHeaderFlags.checkType);
}
/**
* Gets the ID of the integrity check used in this XZ Stream.
*
* @return the Check ID specified in the XZ Stream Header
*/
public int getCheckType() {
return streamHeaderFlags.checkType;
}
/**
* Gets the name of the integrity check used in this XZ Stream.
*
* @return the name of the check specified in the XZ Stream Header
*/
public String getCheckName() {
return check.getName();
}
/**
* Decompresses the next byte from this input stream.
* <p>
* Reading lots of data with <code>read()</code> from this input stream
* may be inefficient. Wrap it in {@link java.io.BufferedInputStream}
* if you need to read lots of data one byte at a time.
*
* @return the next decompressed byte, or <code>-1</code>
* to indicate the end of the compressed stream
*
* @throws CorruptedInputException
* @throws UnsupportedOptionsException
* @throws MemoryLimitException
*
* @throws XZIOException if the stream has been closed
*
* @throws EOFException
* compressed input is truncated or corrupt
*
* @throws IOException may be thrown by <code>in</code>
*/
public int read() throws IOException {
return read(tempBuf, 0, 1) == -1 ? -1 : (tempBuf[0] & 0xFF);
}
/**
* Decompresses into an array of bytes.
* <p>
* If <code>len</code> is zero, no bytes are read and <code>0</code>
* is returned. Otherwise this will try to decompress <code>len</code>
* bytes of uncompressed data. Less than <code>len</code> bytes may
* be read only in the following situations:
* <ul>
* <li>The end of the compressed data was reached successfully.</li>
* <li>An error is detected after at least one but less <code>len</code>
* bytes have already been successfully decompressed.
* The next call with non-zero <code>len</code> will immediately
* throw the pending exception.</li>
* <li>An exception is thrown.</li>
* </ul>
*
* @param buf target buffer for uncompressed data
* @param off start offset in <code>buf</code>
* @param len maximum number of uncompressed bytes to read
*
* @return number of bytes read, or <code>-1</code> to indicate
* the end of the compressed stream
*
* @throws CorruptedInputException
* @throws UnsupportedOptionsException
* @throws MemoryLimitException
*
* @throws XZIOException if the stream has been closed
*
* @throws EOFException
* compressed input is truncated or corrupt
*
* @throws IOException may be thrown by <code>in</code>
*/
public int read(byte[] buf, int off, int len) throws IOException {
if (off < 0 || len < 0 || off + len < 0 || off + len > buf.length)
throw new IndexOutOfBoundsException();
if (len == 0)
return 0;
if (in == null)
throw new XZIOException("Stream closed");
if (exception != null)
throw exception;
if (endReached)
return -1;
int size = 0;
try {
while (len > 0) {
if (blockDecoder == null) {
try {
blockDecoder = new BlockInputStream(
in, check, verifyCheck, memoryLimit, -1, -1);
} catch (IndexIndicatorException e) {
indexHash.validate(in);
validateStreamFooter();
endReached = true;
return size > 0 ? size : -1;
}
}
int ret = blockDecoder.read(buf, off, len);
if (ret > 0) {
size += ret;
off += ret;
len -= ret;
} else if (ret == -1) {
indexHash.add(blockDecoder.getUnpaddedSize(),
blockDecoder.getUncompressedSize());
blockDecoder = null;
}
}
} catch (IOException e) {
exception = e;
if (size == 0)
throw e;
}
return size;
}
private void validateStreamFooter() throws IOException {
byte[] buf = new byte[DecoderUtil.STREAM_HEADER_SIZE];
new DataInputStream(in).readFully(buf);
StreamFlags streamFooterFlags = DecoderUtil.decodeStreamFooter(buf);
if (!DecoderUtil.areStreamFlagsEqual(streamHeaderFlags,
streamFooterFlags)
|| indexHash.getIndexSize() != streamFooterFlags.backwardSize)
throw new CorruptedInputException(
"XZ Stream Footer does not match Stream Header");
}
/**
* Returns the number of uncompressed bytes that can be read
* without blocking. The value is returned with an assumption
* that the compressed input data will be valid. If the compressed
* data is corrupt, <code>CorruptedInputException</code> may get
* thrown before the number of bytes claimed to be available have
* been read from this input stream.
*
* @return the number of uncompressed bytes that can be read
* without blocking
*/
public int available() throws IOException {
if (in == null)
throw new XZIOException("Stream closed");
if (exception != null)
throw exception;
return blockDecoder == null ? 0 : blockDecoder.available();
}
/**
* Closes the stream and calls <code>in.close()</code>.
* If the stream was already closed, this does nothing.
*
* @throws IOException if thrown by <code>in.close()</code>
*/
public void close() throws IOException {
if (in != null) {
try {
in.close();
} finally {
in = null;
}
}
}
}