// InflaterInputStream.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 System.IO;
using ICSharpCode.SharpZipLib.Zip.Compression;
using ICSharpCode.SharpZipLib.Checksums;
namespace ICSharpCode.SharpZipLib.Zip.Compression.Streams
{
/// <summary>
/// This filter stream is used to decompress data compressed baseInputStream the "deflate"
/// format. The "deflate" format is described baseInputStream RFC 1951.
///
/// This stream may form the basis for other decompression filters, such
/// as the <code>GzipInputStream</code>.
///
/// author of the original java version : John Leuner
/// </summary>
public class InflaterInputStream : Stream
{
//Variables
/// <summary>
/// Decompressor for this filter
/// </summary>
protected Inflater inf;
/// <summary>
/// Byte array used as a buffer
/// </summary>
protected byte[] buf;
/// <summary>
/// Size of buffer
/// </summary>
protected int len;
//We just use this if we are decoding one byte at a time with the read() call
private byte[] onebytebuffer = new byte[1];
/// <summary>
/// base stream the inflater depends on.
/// </summary>
protected Stream baseInputStream;
protected long csize;
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override bool CanRead {
get {
return baseInputStream.CanRead;
}
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override bool CanSeek {
get {
return false;
// return baseInputStream.CanSeek;
}
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override bool CanWrite {
get {
return baseInputStream.CanWrite;
}
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override long Length {
get {
return len;
}
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override long Position {
get {
return baseInputStream.Position;
}
set {
baseInputStream.Position = value;
}
}
/// <summary>
/// Flushes the baseInputStream
/// </summary>
public override void Flush()
{
baseInputStream.Flush();
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override long Seek(long offset, SeekOrigin origin)
{
throw new NotSupportedException("Seek not supported"); // -jr- 01-Dec-2003
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override void SetLength(long val)
{
baseInputStream.SetLength(val);
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override void Write(byte[] array, int offset, int count)
{
baseInputStream.Write(array, offset, count);
}
/// <summary>
/// I needed to implement the abstract member.
/// </summary>
public override void WriteByte(byte val)
{
baseInputStream.WriteByte(val);
}
// -jr- 01-Dec-2003 This may be flawed for some base streams? Depends on implementation of BeginWrite
public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
{
throw new NotSupportedException("Asynch write not currently supported");
}
//Constructors
/// <summary>
/// Create an InflaterInputStream with the default decompresseor
/// and a default buffer size.
/// </summary>
/// <param name = "baseInputStream">
/// the InputStream to read bytes from
/// </param>
public InflaterInputStream(Stream baseInputStream) : this(baseInputStream, new Inflater(), 4096)
{
}
/// <summary>
/// Create an InflaterInputStream with the specified decompresseor
/// and a default buffer size.
/// </summary>
/// <param name = "baseInputStream">
/// the InputStream to read bytes from
/// </param>
/// <param name = "inf">
/// the decompressor used to decompress data read from baseInputStream
/// </param>
public InflaterInputStream(Stream baseInputStream, Inflater inf) : this(baseInputStream, inf, 4096)
{
}
/// <summary>
/// Create an InflaterInputStream with the specified decompresseor
/// and a specified buffer size.
/// </summary>
/// <param name = "baseInputStream">
/// the InputStream to read bytes from
/// </param>
/// <param name = "inf">
/// the decompressor used to decompress data read from baseInputStream
/// </param>
/// <param name = "size">
/// size of the buffer to use
/// </param>
public InflaterInputStream(Stream baseInputStream, Inflater inf, int size)
{
this.baseInputStream = baseInputStream;
this.inf = inf;
try {
this.len = (int)baseInputStream.Length;
} catch (Exception) {
// the stream may not support .Length
this.len = 0;
}
if (size <= 0) {
throw new ArgumentOutOfRangeException("size <= 0");
}
buf = new byte[size]; //Create the buffer
}
//Methods
/// <summary>
/// Returns 0 once the end of the stream (EOF) has been reached.
/// Otherwise returns 1.
/// </summary>
public virtual int Available {
get {
return inf.IsFinished ? 0 : 1;
}
}
/// <summary>
/// Closes the input stream
/// </summary>
public override void Close()
{
baseInputStream.Close();
}
/// <summary>
/// Fills the buffer with more data to decompress.
/// </summary>
protected void Fill()
{
len = baseInputStream.Read(buf, 0, buf.Length);
// decrypting crypted data
if (cryptbuffer != null) {
DecryptBlock(buf, 0, System.Math.Min((int)(csize - inf.TotalIn), buf.Length));
}
if (len <= 0) {
throw new ApplicationException("Deflated stream ends early.");
}
inf.SetInput(buf, 0, len);
}
/// <summary>
/// Reads one byte of decompressed data.
///
/// The byte is baseInputStream the lower 8 bits of the int.
/// </summary>
public override int ReadByte()
{
int nread = Read(onebytebuffer, 0, 1); //read one byte
if (nread > 0) {
return onebytebuffer[0] & 0xff;
}
return -1; // ok
}
/// <summary>
/// Decompresses data into the byte array
/// </summary>
/// <param name ="b">
/// the array to read and decompress data into
/// </param>
/// <param name ="off">
/// the offset indicating where the data should be placed
/// </param>
/// <param name ="len">
/// the number of bytes to decompress
/// </param>
public override int Read(byte[] b, int off, int len)
{
for (;;) {
int count;
try {
count = inf.Inflate(b, off, len);
} catch (Exception e) {
throw new ZipException(e.ToString());
}
if (count > 0) {
return count;
}
if (inf.IsNeedingDictionary) {
throw new ZipException("Need a dictionary");
} else if (inf.IsFinished) {
return 0;
} else if (inf.IsNeedingInput) {
Fill();
} else {
throw new InvalidOperationException("Don't know what to do");
}
}
}
/// <summary>
/// Skip specified number of bytes of uncompressed data
/// </summary>
/// <param name ="n">
/// number of bytes to skip
/// </param>
public long Skip(long n)
{
if (n < 0) {
throw new ArgumentOutOfRangeException("n");
}
int len = 2048;
if (n < len) {
len = (int) n;
}
byte[] tmp = new byte[len];
return (long)baseInputStream.Read(tmp, 0, tmp.Length);
}
#region Encryption stuff
protected byte[] cryptbuffer = null;
uint[] keys = null;
protected byte DecryptByte()
{
uint temp = ((keys[2] & 0xFFFF) | 2);
return (byte)((temp * (temp ^ 1)) >> 8);
}
protected void DecryptBlock(byte[] buf, int off, int len)
{
for (int i = off; i < off + len; ++i) {
buf[i] ^= DecryptByte();
UpdateKeys(buf[i]);
}
}
protected void InitializePassword(string password)
{
keys = new uint[] {
0x12345678,
0x23456789,
0x34567890
};
for (int i = 0; i < password.Length; ++i) {
UpdateKeys((byte)password[i]);
}
}
protected void UpdateKeys(byte ch)
{
keys[0] = Crc32.ComputeCrc32(keys[0], ch);
keys[1] = keys[1] + (byte)keys[0];
keys[1] = keys[1] * 134775813 + 1;
keys[2] = Crc32.ComputeCrc32(keys[2], (byte)(keys[1] >> 24));
}
#endregion
}
}