| /* |
| * XZInputStream |
| * |
| * 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; |
| |
| /** |
| * Decompresses a .xz file in streamed mode (no seeking). |
| * <p> |
| * Use this to decompress regular standalone .xz files. This reads from |
| * its input stream until the end of the input or until an error occurs. |
| * This supports decompressing concatenated .xz files. |
| * |
| * <h4>Typical use cases</h4> |
| * <p> |
| * Getting an input stream to decompress a .xz file: |
| * <p><blockquote><pre> |
| * InputStream infile = new FileInputStream("foo.xz"); |
| * XZInputStream inxz = new XZInputStream(infile); |
| * </pre></blockquote> |
| * <p> |
| * It's important to keep in mind that decompressor memory usage depends |
| * on the settings used to compress the file. The worst-case memory usage |
| * of XZInputStream is currently 1.5 GiB. Still, very few files will |
| * require more than about 65 MiB because that's how much decompressing |
| * a file created with the highest preset level will need, and only a few |
| * people use settings other than the predefined presets. |
| * <p> |
| * It is possible to specify a memory usage limit for |
| * <code>XZInputStream</code>. If decompression requires more memory than |
| * the specified limit, MemoryLimitException will be thrown when reading |
| * from the stream. For example, the following sets the memory usage limit |
| * to 100 MiB: |
| * <p><blockquote><pre> |
| * InputStream infile = new FileInputStream("foo.xz"); |
| * XZInputStream inxz = new XZInputStream(infile, 100 * 1024); |
| * </pre></blockquote> |
| * |
| * <h4>When uncompressed size is known beforehand</h4> |
| * <p> |
| * If you are decompressing complete files 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. (This advice seems to |
| * apply to |
| * {@link java.util.zip.GZIPInputStream java.util.zip.GZIPInputStream} too.) |
| * |
| * @see SingleXZInputStream |
| */ |
| public class XZInputStream extends InputStream { |
| private final int memoryLimit; |
| private InputStream in; |
| private SingleXZInputStream xzIn; |
| private final boolean verifyCheck; |
| private boolean endReached = false; |
| private IOException exception = null; |
| |
| private final byte[] tempBuf = new byte[1]; |
| |
| /** |
| * Creates a new XZ decompressor 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 XZInputStream(InputStream in) throws IOException { |
| this(in, -1); |
| } |
| |
| /** |
| * Creates a new XZ decompressor with an optional memory usage limit. |
| * <p> |
| * This is identical to <code>XZInputStream(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 XZInputStream(InputStream in, int memoryLimit) throws IOException { |
| this(in, memoryLimit, true); |
| } |
| |
| /** |
| * Creates a new XZ decompressor with an optional memory usage limit |
| * and ability to disable verification of integrity checks. |
| * <p> |
| * This is identical to <code>XZInputStream(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 XZInputStream(InputStream in, int memoryLimit, boolean verifyCheck) |
| throws IOException { |
| this.in = in; |
| this.memoryLimit = memoryLimit; |
| this.verifyCheck = verifyCheck; |
| this.xzIn = new SingleXZInputStream(in, memoryLimit, verifyCheck); |
| } |
| |
| /** |
| * 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 (xzIn == null) { |
| prepareNextStream(); |
| if (endReached) |
| return size == 0 ? -1 : size; |
| } |
| |
| int ret = xzIn.read(buf, off, len); |
| |
| if (ret > 0) { |
| size += ret; |
| off += ret; |
| len -= ret; |
| } else if (ret == -1) { |
| xzIn = null; |
| } |
| } |
| } catch (IOException e) { |
| exception = e; |
| if (size == 0) |
| throw e; |
| } |
| |
| return size; |
| } |
| |
| private void prepareNextStream() throws IOException { |
| DataInputStream inData = new DataInputStream(in); |
| byte[] buf = new byte[DecoderUtil.STREAM_HEADER_SIZE]; |
| |
| // The size of Stream Padding must be a multiple of four bytes, |
| // all bytes zero. |
| do { |
| // First try to read one byte to see if we have reached the end |
| // of the file. |
| int ret = inData.read(buf, 0, 1); |
| if (ret == -1) { |
| endReached = true; |
| return; |
| } |
| |
| // Since we got one byte of input, there must be at least |
| // three more available in a valid file. |
| inData.readFully(buf, 1, 3); |
| |
| } while (buf[0] == 0 && buf[1] == 0 && buf[2] == 0 && buf[3] == 0); |
| |
| // Not all bytes are zero. In a valid Stream it indicates the |
| // beginning of the next Stream. Read the rest of the Stream Header |
| // and initialize the XZ decoder. |
| inData.readFully(buf, 4, DecoderUtil.STREAM_HEADER_SIZE - 4); |
| |
| try { |
| xzIn = new SingleXZInputStream(in, memoryLimit, verifyCheck, buf); |
| } catch (XZFormatException e) { |
| // Since this isn't the first .xz Stream, it is more |
| // logical to tell that the data is corrupt. |
| throw new CorruptedInputException( |
| "Garbage after a valid XZ Stream"); |
| } |
| } |
| |
| /** |
| * 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 xzIn == null ? 0 : xzIn.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; |
| } |
| } |
| } |
| } |
