// Inflater.cs
// Copyright (C) 2001 Mike Krueger
//
// This file was translated from java, it was part of the GNU Classpath
// Copyright (C) 2001 Free Software Foundation, Inc.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library. Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module. An independent module is a module which is not derived from
// or based on this library. If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
using System;
using ICSharpCode.SharpZipLib.Checksums;
using ICSharpCode.SharpZipLib.Zip.Compression.Streams;
namespace ICSharpCode.SharpZipLib.Zip.Compression
{
/// <summary>
/// Inflater is used to decompress data that has been compressed according
/// to the "deflate" standard described in rfc1950.
///
/// The usage is as following. First you have to set some input with
/// <code>setInput()</code>, then inflate() it. If inflate doesn't
/// inflate any bytes there may be three reasons:
/// <ul>
/// <li>needsInput() returns true because the input buffer is empty.
/// You have to provide more input with <code>setInput()</code>.
/// NOTE: needsInput() also returns true when, the stream is finished.
/// </li>
/// <li>needsDictionary() returns true, you have to provide a preset
/// dictionary with <code>setDictionary()</code>.</li>
/// <li>finished() returns true, the inflater has finished.</li>
/// </ul>
/// Once the first output byte is produced, a dictionary will not be
/// needed at a later stage.
///
/// author of the original java version : John Leuner, Jochen Hoenicke
/// </summary>
public class Inflater
{
/// <summary>
/// Copy lengths for literal codes 257..285
/// </summary>
private static int[] CPLENS = {
3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258
};
/// <summary>
/// Extra bits for literal codes 257..285
/// </summary>
private static int[] CPLEXT = {
0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0
};
/// <summary>
/// Copy offsets for distance codes 0..29
/// </summary>
private static int[] CPDIST = {
1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
8193, 12289, 16385, 24577
};
/// <summary>
/// Extra bits for distance codes
/// </summary>
private static int[] CPDEXT = {
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
12, 12, 13, 13
};
/// <summary>
/// This are the state in which the inflater can be.
/// </summary>
private const int DECODE_HEADER = 0;
private const int DECODE_DICT = 1;
private const int DECODE_BLOCKS = 2;
private const int DECODE_STORED_LEN1 = 3;
private const int DECODE_STORED_LEN2 = 4;
private const int DECODE_STORED = 5;
private const int DECODE_DYN_HEADER = 6;
private const int DECODE_HUFFMAN = 7;
private const int DECODE_HUFFMAN_LENBITS = 8;
private const int DECODE_HUFFMAN_DIST = 9;
private const int DECODE_HUFFMAN_DISTBITS = 10;
private const int DECODE_CHKSUM = 11;
private const int FINISHED = 12;
/// <summary>
/// This variable contains the current state.
/// </summary>
private int mode;
/// <summary>
/// The adler checksum of the dictionary or of the decompressed
/// stream, as it is written in the header resp. footer of the
/// compressed stream.
/// Only valid if mode is DECODE_DICT or DECODE_CHKSUM.
/// </summary>
private int readAdler;
/// <summary>
/// The number of bits needed to complete the current state. This
/// is valid, if mode is DECODE_DICT, DECODE_CHKSUM,
/// DECODE_HUFFMAN_LENBITS or DECODE_HUFFMAN_DISTBITS.
/// </summary>
private int neededBits;
private int repLength, repDist;
private int uncomprLen;
/// <summary>
/// True, if the last block flag was set in the last block of the
/// inflated stream. This means that the stream ends after the
/// current block.
/// </summary>
private bool isLastBlock;
/// <summary>
/// The total number of inflated bytes.
/// </summary>
private int totalOut;
/// <summary>
/// The total number of bytes set with setInput(). This is not the
/// value returned by getTotalIn(), since this also includes the
/// unprocessed input.
/// </summary>
private int totalIn;
/// <summary>
/// This variable stores the nowrap flag that was given to the constructor.
/// True means, that the inflated stream doesn't contain a header nor the
/// checksum in the footer.
/// </summary>
private bool nowrap;
private StreamManipulator input;
private OutputWindow outputWindow;
private InflaterDynHeader dynHeader;
private InflaterHuffmanTree litlenTree, distTree;
private Adler32 adler;
/// <summary>
/// Creates a new inflater.
/// </summary>
public Inflater() : this(false)
{
}
/// <summary>
/// Creates a new inflater.
/// </summary>
/// <param name="nowrap">
/// true if no header and checksum field appears in the
/// stream. This is used for GZIPed input. For compatibility with
/// Sun JDK you should provide one byte of input more than needed in
/// this case.
/// </param>
public Inflater(bool nowrap)
{
this.nowrap = nowrap;
this.adler = new Adler32();
input = new StreamManipulator();
outputWindow = new OutputWindow();
mode = nowrap ? DECODE_BLOCKS : DECODE_HEADER;
}
/// <summary>
/// Resets the inflater so that a new stream can be decompressed. All
/// pending input and output will be discarded.
/// </summary>
public void Reset()
{
mode = nowrap ? DECODE_BLOCKS : DECODE_HEADER;
totalIn = totalOut = 0;
input.Reset();
outputWindow.Reset();
dynHeader = null;
litlenTree = null;
distTree = null;
isLastBlock = false;
adler.Reset();
}
/// <summary>
/// Decodes the deflate header.
/// </summary>
/// <returns>
/// false if more input is needed.
/// </returns>
/// <exception cref="System.FormatException">
/// if header is invalid.
/// </exception>
private bool DecodeHeader()
{
int header = input.PeekBits(16);
if (header < 0) {
return false;
}
input.DropBits(16);
/* The header is written in "wrong" byte order */
header = ((header << 8) | (header >> 8)) & 0xffff;
if (header % 31 != 0) {
throw new FormatException("Header checksum illegal");
}
if ((header & 0x0f00) != (Deflater.DEFLATED << 8)) {
throw new FormatException("Compression Method unknown");
}
/* Maximum size of the backwards window in bits.
* We currently ignore this, but we could use it to make the
* inflater window more space efficient. On the other hand the
* full window (15 bits) is needed most times, anyway.
int max_wbits = ((header & 0x7000) >> 12) + 8;
*/
if ((header & 0x0020) == 0) { // Dictionary flag?
mode = DECODE_BLOCKS;
} else {
mode = DECODE_DICT;
neededBits = 32;
}
return true;
}
/// <summary>
/// Decodes the dictionary checksum after the deflate header.
/// </summary>
/// <returns>
/// false if more input is needed.
/// </returns>
private bool DecodeDict()
{
while (neededBits > 0) {
int dictByte = input.PeekBits(8);
if (dictByte < 0) {
return false;
}
input.DropBits(8);
readAdler = (readAdler << 8) | dictByte;
neededBits -= 8;
}
return false;
}
/// <summary>
/// Decodes the huffman encoded symbols in the input stream.
/// </summary>
/// <returns>
/// false if more input is needed, true if output window is
/// full or the current block ends.
/// </returns>
/// <exception cref="System.FormatException">
/// if deflated stream is invalid.
/// </exception>
private bool DecodeHuffman()
{
int free = outputWindow.GetFreeSpace();
while (free >= 258) {
int symbol;
switch (mode) {
case DECODE_HUFFMAN:
/* This is the inner loop so it is optimized a bit */
while (((symbol = litlenTree.GetSymbol(input)) & ~0xff) == 0) {
outputWindow.Write(symbol);
if (--free < 258) {
return true;
}
}
if (symbol < 257) {
if (symbol < 0) {
return false;
} else {
/* symbol == 256: end of block */
distTree = null;
litlenTree = null;
mode = DECODE_BLOCKS;
return true;
}
}
try {
repLength = CPLENS[symbol - 257];
neededBits = CPLEXT[symbol - 257];
} catch (Exception) {
throw new FormatException("Illegal rep length code");
}
goto case DECODE_HUFFMAN_LENBITS;/* fall through */
case DECODE_HUFFMAN_LENBITS:
if (neededBits > 0) {
mode = DECODE_HUFFMAN_LENBITS;
int i = input.PeekBits(neededBits);
if (i < 0) {
return false;
}
input.DropBits(neededBits);
repLength += i;
}
mode = DECODE_HUFFMAN_DIST;
goto case DECODE_HUFFMAN_DIST;/* fall through */
case DECODE_HUFFMAN_DIST:
symbol = distTree.GetSymbol(input);
if (symbol < 0) {
return false;
}
try {
repDist = CPDIST[symbol];
neededBits = CPDEXT[symbol];
} catch (Exception) {
throw new FormatException("Illegal rep dist code");
}
goto case DECODE_HUFFMAN_DISTBITS;/* fall through */
case DECODE_HUFFMAN_DISTBITS:
if (neededBits > 0) {
mode = DECODE_HUFFMAN_DISTBITS;
int i = input.PeekBits(neededBits);
if (i < 0) {
return false;
}
input.DropBits(neededBits);
repDist += i;
}
outputWindow.Repeat(repLength, repDist);
free -= repLength;
mode = DECODE_HUFFMAN;
break;
default:
throw new FormatException();
}
}
return true;
}
/// <summary>
/// Decodes the adler checksum after the deflate stream.
/// </summary>
/// <returns>
/// false if more input is needed.
/// </returns>
/// <exception cref="System.FormatException">
/// DataFormatException, if checksum doesn't match.
/// </exception>
private bool DecodeChksum()
{
while (neededBits > 0) {
int chkByte = input.PeekBits(8);
if (chkByte < 0) {
return false;
}
input.DropBits(8);
readAdler = (readAdler << 8) | chkByte;
neededBits -= 8;
}
if ((int) adler.Value != readAdler) {
throw new FormatException("Adler chksum doesn't match: " + (int)adler.Value + " vs. " + readAdler);
}
mode = FINISHED;
return false;
}
/// <summary>
/// Decodes the deflated stream.
/// </summary>
/// <returns>
/// false if more input is needed, or if finished.
/// </returns>
/// <exception cref="System.FormatException">
/// DataFormatException, if deflated stream is invalid.
/// </exception>
private bool Decode()
{
switch (mode) {
case DECODE_HEADER:
return DecodeHeader();
case DECODE_DICT:
return DecodeDict();
case DECODE_CHKSUM:
return DecodeChksum();
case DECODE_BLOCKS:
if (isLastBlock) {
if (nowrap) {
mode = FINISHED;
return false;
} else {
input.SkipToByteBoundary();
neededBits = 32;
mode = DECODE_CHKSUM;
return true;
}
}
int type = input.PeekBits(3);
if (type < 0) {
return false;
}
input.DropBits(3);
if ((type & 1) != 0) {
isLastBlock = true;
}
switch (type >> 1){
case DeflaterConstants.STORED_BLOCK:
input.SkipToByteBoundary();
mode = DECODE_STORED_LEN1;
break;
case DeflaterConstants.STATIC_TREES:
litlenTree = InflaterHuffmanTree.defLitLenTree;
distTree = InflaterHuffmanTree.defDistTree;
mode = DECODE_HUFFMAN;
break;
case DeflaterConstants.DYN_TREES:
dynHeader = new InflaterDynHeader();
mode = DECODE_DYN_HEADER;
break;
default:
throw new FormatException("Unknown block type "+type);
}
return true;
case DECODE_STORED_LEN1:
{
if ((uncomprLen = input.PeekBits(16)) < 0) {
return false;
}
input.DropBits(16);
mode = DECODE_STORED_LEN2;
}
goto case DECODE_STORED_LEN2; /* fall through */
case DECODE_STORED_LEN2:
{
int nlen = input.PeekBits(16);
if (nlen < 0) {
return false;
}
input.DropBits(16);
if (nlen != (uncomprLen ^ 0xffff)) {
throw new FormatException("broken uncompressed block");
}
mode = DECODE_STORED;
}
goto case DECODE_STORED;/* fall through */
case DECODE_STORED:
{
int more = outputWindow.CopyStored(input, uncomprLen);
uncomprLen -= more;
if (uncomprLen == 0) {
mode = DECODE_BLOCKS;
return true;
}
return !input.IsNeedingInput;
}
case DECODE_DYN_HEADER:
if (!dynHeader.Decode(input)) {
return false;
}
litlenTree = dynHeader.BuildLitLenTree();
distTree = dynHeader.BuildDistTree();
mode = DECODE_HUFFMAN;
goto case DECODE_HUFFMAN; /* fall through */
case DECODE_HUFFMAN:
case DECODE_HUFFMAN_LENBITS:
case DECODE_HUFFMAN_DIST:
case DECODE_HUFFMAN_DISTBITS:
return DecodeHuffman();
case FINISHED:
return false;
default:
throw new FormatException();
}
}
/// <summary>
/// Sets the preset dictionary. This should only be called, if
/// needsDictionary() returns true and it should set the same
/// dictionary, that was used for deflating. The getAdler()
/// function returns the checksum of the dictionary needed.
/// </summary>
/// <param name="buffer">
/// the dictionary.
/// </param>
/// <exception cref="System.InvalidOperationException">
/// if no dictionary is needed.
/// </exception>
/// <exception cref="System.ArgumentException">
/// if the dictionary checksum is wrong.
/// </exception>
public void SetDictionary(byte[] buffer)
{
SetDictionary(buffer, 0, buffer.Length);
}
/// <summary>
/// Sets the preset dictionary. This should only be called, if
/// needsDictionary() returns true and it should set the same
/// dictionary, that was used for deflating. The getAdler()
/// function returns the checksum of the dictionary needed.
/// </summary>
/// <param name="buffer">
/// the dictionary.
/// </param>
/// <param name="off">
/// the offset into buffer where the dictionary starts.
/// </param>
/// <param name="len">
/// the length of the dictionary.
/// </param>
/// <exception cref="System.InvalidOperationException">
/// if no dictionary is needed.
/// </exception>
/// <exception cref="System.ArgumentException">
/// if the dictionary checksum is wrong.
/// </exception>
/// <exception cref="System.ArgumentOutOfRangeException">
/// if the off and/or len are wrong.
/// </exception>
public void SetDictionary(byte[] buffer, int off, int len)
{
if (!IsNeedingDictionary) {
throw new InvalidOperationException();
}
adler.Update(buffer, off, len);
if ((int)adler.Value != readAdler) {
throw new ArgumentException("Wrong adler checksum");
}
adler.Reset();
outputWindow.CopyDict(buffer, off, len);
mode = DECODE_BLOCKS;
}
/// <summary>
/// Sets the input. This should only be called, if needsInput()
/// returns true.
/// </summary>
/// <param name="buf">
/// the input.
/// </param>
/// <exception cref="System.InvalidOperationException">
/// if no input is needed.
/// </exception>
public void SetInput(byte[] buf)
{
SetInput(buf, 0, buf.Length);
}
/// <summary>
/// Sets the input. This should only be called, if needsInput()
/// returns true.
/// </summary>
/// <param name="buf">
/// the input.
/// </param>
/// <param name="off">
/// the offset into buffer where the input starts.
/// </param>
/// <param name="len">
/// the length of the input.
/// </param>
/// <exception cref="System.InvalidOperationException">
/// if no input is needed.
/// </exception>
/// <exception cref="System.ArgumentOutOfRangeException">
/// if the off and/or len are wrong.
/// </exception>
public void SetInput(byte[] buf, int off, int len)
{
input.SetInput(buf, off, len);
totalIn += len;
}
/// <summary>
/// Inflates the compressed stream to the output buffer. If this
/// returns 0, you should check, whether needsDictionary(),
/// needsInput() or finished() returns true, to determine why no
/// further output is produced.
/// </summary>
/// <param name = "buf">
/// the output buffer.
/// </param>
/// <returns>
/// the number of bytes written to the buffer, 0 if no further
/// output can be produced.
/// </returns>
/// <exception cref="System.ArgumentOutOfRangeException">
/// if buf has length 0.
/// </exception>
/// <exception cref="System.FormatException">
/// if deflated stream is invalid.
/// </exception>
public int Inflate(byte[] buf)
{
return Inflate(buf, 0, buf.Length);
}
/// <summary>
/// Inflates the compressed stream to the output buffer. If this
/// returns 0, you should check, whether needsDictionary(),
/// needsInput() or finished() returns true, to determine why no
/// further output is produced.
/// </summary>
/// <param name = "buf">
/// the output buffer.
/// </param>
/// <param name = "off">
/// the offset into buffer where the output should start.
/// </param>
/// <param name = "len">
/// the maximum length of the output.
/// </param>
/// <returns>
/// the number of bytes written to the buffer, 0 if no further output can be produced.
/// </returns>
/// <exception cref="System.ArgumentOutOfRangeException">
/// if len is <= 0.
/// </exception>
/// <exception cref="System.ArgumentOutOfRangeException">
/// if the off and/or len are wrong.
/// </exception>
/// <exception cref="System.FormatException">
/// if deflated stream is invalid.
/// </exception>
public int Inflate(byte[] buf, int off, int len)
{
if (len < 0) {
throw new ArgumentOutOfRangeException("len < 0");
}
// Special case: len may be zero
if (len == 0) {
if (IsFinished == false) {// -jr- 08-Nov-2003 INFLATE_BUG fix..
Decode();
}
return 0;
}
/* // Check for correct buff, off, len triple
if (off < 0 || off + len >= buf.Length) {
throw new ArgumentException("off/len outside buf bounds");
}*/
int count = 0;
int more;
do {
if (mode != DECODE_CHKSUM) {
/* Don't give away any output, if we are waiting for the
* checksum in the input stream.
*
* With this trick we have always:
* needsInput() and not finished()
* implies more output can be produced.
*/
more = outputWindow.CopyOutput(buf, off, len);
adler.Update(buf, off, more);
off += more;
count += more;
totalOut += more;
len -= more;
if (len == 0) {
return count;
}
}
} while (Decode() || (outputWindow.GetAvailable() > 0 && mode != DECODE_CHKSUM));
return count;
}
/// <summary>
/// Returns true, if the input buffer is empty.
/// You should then call setInput().
/// NOTE: This method also returns true when the stream is finished.
/// </summary>
public bool IsNeedingInput {
get {
return input.IsNeedingInput;
}
}
/// <summary>
/// Returns true, if a preset dictionary is needed to inflate the input.
/// </summary>
public bool IsNeedingDictionary {
get {
return mode == DECODE_DICT && neededBits == 0;
}
}
/// <summary>
/// Returns true, if the inflater has finished. This means, that no
/// input is needed and no output can be produced.
/// </summary>
public bool IsFinished {
get {
return mode == FINISHED && outputWindow.GetAvailable() == 0;
}
}
/// <summary>
/// Gets the adler checksum. This is either the checksum of all
/// uncompressed bytes returned by inflate(), or if needsDictionary()
/// returns true (and thus no output was yet produced) this is the
/// adler checksum of the expected dictionary.
/// </summary>
/// <returns>
/// the adler checksum.
/// </returns>
public int Adler {
get {
return IsNeedingDictionary ? readAdler : (int) adler.Value;
}
}
/// <summary>
/// Gets the total number of output bytes returned by inflate().
/// </summary>
/// <returns>
/// the total number of output bytes.
/// </returns>
public int TotalOut {
get {
return totalOut;
}
}
/// <summary>
/// Gets the total number of processed compressed input bytes.
/// </summary>
/// <returns>
/// the total number of bytes of processed input bytes.
/// </returns>
public int TotalIn {
get {
return totalIn - RemainingInput;
}
}
/// <summary>
/// Gets the number of unprocessed input. Useful, if the end of the
/// stream is reached and you want to further process the bytes after
/// the deflate stream.
/// </summary>
/// <returns>
/// the number of bytes of the input which were not processed.
/// </returns>
public int RemainingInput {
get {
return input.AvailableBytes;
}
}
}
}