// ZlibBaseStream.cs
// ------------------------------------------------------------------
//
// Copyright (c) 2009 Dino Chiesa and Microsoft Corporation.
// All rights reserved.
//
// This code module is part of DotNetZip, a zipfile class library.
//
// ------------------------------------------------------------------
//
// This code is licensed under the Microsoft Public License.
// See the file License.txt for the license details.
// More info on: http://dotnetzip.codeplex.com
//
// ------------------------------------------------------------------
//
// last saved (in emacs):
// Time-stamp: <2011-August-06 21:22:38>
//
// ------------------------------------------------------------------
//
// This module defines the ZlibBaseStream class, which is an intnernal
// base class for DeflateStream, ZlibStream and GZipStream.
//
// ------------------------------------------------------------------
using System;
using System.IO;
namespace BestHTTP.Decompression.Zlib
{
internal enum ZlibStreamFlavor { ZLIB = 1950, DEFLATE = 1951, GZIP = 1952 }
internal class ZlibBaseStream : System.IO.Stream
{
protected internal ZlibCodec _z = null; // deferred init... new ZlibCodec();
protected internal StreamMode _streamMode = StreamMode.Undefined;
protected internal FlushType _flushMode;
protected internal ZlibStreamFlavor _flavor;
protected internal CompressionMode _compressionMode;
protected internal CompressionLevel _level;
protected internal bool _leaveOpen;
protected internal byte[] _workingBuffer;
protected internal int _bufferSize = ZlibConstants.WorkingBufferSizeDefault;
protected internal int windowBitsMax;
protected internal byte[] _buf1 = new byte[1];
protected internal System.IO.Stream _stream;
protected internal CompressionStrategy Strategy = CompressionStrategy.Default;
// workitem 7159
BestHTTP.Decompression.Crc.CRC32 crc;
protected internal string _GzipFileName;
protected internal string _GzipComment;
protected internal DateTime _GzipMtime;
protected internal int _gzipHeaderByteCount;
internal int Crc32 { get { if (crc == null) return 0; return crc.Crc32Result; } }
public ZlibBaseStream(System.IO.Stream stream,
CompressionMode compressionMode,
CompressionLevel level,
ZlibStreamFlavor flavor,
bool leaveOpen)
:this(stream, compressionMode, level, flavor,leaveOpen, ZlibConstants.WindowBitsDefault)
{ }
public ZlibBaseStream(System.IO.Stream stream,
CompressionMode compressionMode,
CompressionLevel level,
ZlibStreamFlavor flavor,
bool leaveOpen,
int windowBits)
: base()
{
this._flushMode = FlushType.None;
//this._workingBuffer = new byte[WORKING_BUFFER_SIZE_DEFAULT];
this._stream = stream;
this._leaveOpen = leaveOpen;
this._compressionMode = compressionMode;
this._flavor = flavor;
this._level = level;
this.windowBitsMax = windowBits;
// workitem 7159
if (flavor == ZlibStreamFlavor.GZIP)
{
this.crc = new BestHTTP.Decompression.Crc.CRC32();
}
}
protected internal bool _wantCompress
{
get
{
return (this._compressionMode == CompressionMode.Compress);
}
}
private ZlibCodec z
{
get
{
if (_z == null)
{
bool wantRfc1950Header = (this._flavor == ZlibStreamFlavor.ZLIB);
_z = new ZlibCodec();
if (this._compressionMode == CompressionMode.Decompress)
{
_z.InitializeInflate(this.windowBitsMax, wantRfc1950Header);
}
else
{
_z.Strategy = Strategy;
_z.InitializeDeflate(this._level, this.windowBitsMax, wantRfc1950Header);
}
}
return _z;
}
}
private byte[] workingBuffer
{
get
{
if (_workingBuffer == null)
_workingBuffer = new byte[_bufferSize];
return _workingBuffer;
}
}
public override void Write(System.Byte[] buffer, int offset, int count)
{
// workitem 7159
// calculate the CRC on the unccompressed data (before writing)
if (crc != null)
crc.SlurpBlock(buffer, offset, count);
if (_streamMode == StreamMode.Undefined)
_streamMode = StreamMode.Writer;
else if (_streamMode != StreamMode.Writer)
throw new ZlibException("Cannot Write after Reading.");
if (count == 0)
return;
// first reference of z property will initialize the private var _z
z.InputBuffer = buffer;
_z.NextIn = offset;
_z.AvailableBytesIn = count;
bool done = false;
do
{
_z.OutputBuffer = workingBuffer;
_z.NextOut = 0;
_z.AvailableBytesOut = _workingBuffer.Length;
int rc = (_wantCompress)
? _z.Deflate(_flushMode)
: _z.Inflate(_flushMode);
if (rc != ZlibConstants.Z_OK && rc != ZlibConstants.Z_STREAM_END)
throw new ZlibException((_wantCompress ? "de" : "in") + "flating: " + _z.Message);
//if (_workingBuffer.Length - _z.AvailableBytesOut > 0)
_stream.Write(_workingBuffer, 0, _workingBuffer.Length - _z.AvailableBytesOut);
done = _z.AvailableBytesIn == 0 && _z.AvailableBytesOut != 0;
// If GZIP and de-compress, we're done when 8 bytes remain.
if (_flavor == ZlibStreamFlavor.GZIP && !_wantCompress)
done = (_z.AvailableBytesIn == 8 && _z.AvailableBytesOut != 0);
}
while (!done);
}
private void finish()
{
if (_z == null) return;
if (_streamMode == StreamMode.Writer)
{
bool done = false;
do
{
_z.OutputBuffer = workingBuffer;
_z.NextOut = 0;
_z.AvailableBytesOut = _workingBuffer.Length;
int rc = (_wantCompress)
? _z.Deflate(FlushType.Finish)
: _z.Inflate(FlushType.Finish);
if (rc != ZlibConstants.Z_STREAM_END && rc != ZlibConstants.Z_OK)
{
string verb = (_wantCompress ? "de" : "in") + "flating";
if (_z.Message == null)
throw new ZlibException(String.Format("{0}: (rc = {1})", verb, rc));
else
throw new ZlibException(verb + ": " + _z.Message);
}
if (_workingBuffer.Length - _z.AvailableBytesOut > 0)
{
_stream.Write(_workingBuffer, 0, _workingBuffer.Length - _z.AvailableBytesOut);
}
done = _z.AvailableBytesIn == 0 && _z.AvailableBytesOut != 0;
// If GZIP and de-compress, we're done when 8 bytes remain.
if (_flavor == ZlibStreamFlavor.GZIP && !_wantCompress)
done = (_z.AvailableBytesIn == 8 && _z.AvailableBytesOut != 0);
}
while (!done);
Flush();
// workitem 7159
if (_flavor == ZlibStreamFlavor.GZIP)
{
if (_wantCompress)
{
// Emit the GZIP trailer: CRC32 and size mod 2^32
int c1 = crc.Crc32Result;
_stream.Write(BitConverter.GetBytes(c1), 0, 4);
int c2 = (Int32)(crc.TotalBytesRead & 0x00000000FFFFFFFF);
_stream.Write(BitConverter.GetBytes(c2), 0, 4);
}
else
{
throw new ZlibException("Writing with decompression is not supported.");
}
}
}
// workitem 7159
else if (_streamMode == StreamMode.Reader)
{
if (_flavor == ZlibStreamFlavor.GZIP)
{
if (!_wantCompress)
{
// workitem 8501: handle edge case (decompress empty stream)
if (_z.TotalBytesOut == 0L)
return;
// Read and potentially verify the GZIP trailer:
// CRC32 and size mod 2^32
byte[] trailer = new byte[8];
// workitems 8679 & 12554
if (_z.AvailableBytesIn < 8)
{
// Make sure we have read to the end of the stream
Array.Copy(_z.InputBuffer, _z.NextIn, trailer, 0, _z.AvailableBytesIn);
int bytesNeeded = 8 - _z.AvailableBytesIn;
int bytesRead = _stream.Read(trailer,
_z.AvailableBytesIn,
bytesNeeded);
if (bytesNeeded != bytesRead)
{
throw new ZlibException(String.Format("Missing or incomplete GZIP trailer. Expected 8 bytes, got {0}.",
_z.AvailableBytesIn + bytesRead));
}
}
else
{
Array.Copy(_z.InputBuffer, _z.NextIn, trailer, 0, trailer.Length);
}
Int32 crc32_expected = BitConverter.ToInt32(trailer, 0);
Int32 crc32_actual = crc.Crc32Result;
Int32 isize_expected = BitConverter.ToInt32(trailer, 4);
Int32 isize_actual = (Int32)(_z.TotalBytesOut & 0x00000000FFFFFFFF);
if (crc32_actual != crc32_expected)
throw new ZlibException(String.Format("Bad CRC32 in GZIP trailer. (actual({0:X8})!=expected({1:X8}))", crc32_actual, crc32_expected));
if (isize_actual != isize_expected)
throw new ZlibException(String.Format("Bad size in GZIP trailer. (actual({0})!=expected({1}))", isize_actual, isize_expected));
}
else
{
throw new ZlibException("Reading with compression is not supported.");
}
}
}
}
private void end()
{
if (z == null)
return;
if (_wantCompress)
{
_z.EndDeflate();
}
else
{
_z.EndInflate();
}
_z = null;
}
public
#if !NETFX_CORE
override
#endif
void Close()
{
if (_stream == null) return;
try
{
finish();
}
finally
{
end();
if (!_leaveOpen) _stream.Dispose();
_stream = null;
}
}
public override void Flush()
{
_stream.Flush();
}
public override System.Int64 Seek(System.Int64 offset, System.IO.SeekOrigin origin)
{
throw new NotImplementedException();
//_outStream.Seek(offset, origin);
}
public override void SetLength(System.Int64 value)
{
_stream.SetLength(value);
nomoreinput = false;
}
#if NOT
public int Read()
{
if (Read(_buf1, 0, 1) == 0)
return 0;
// calculate CRC after reading
if (crc!=null)
crc.SlurpBlock(_buf1,0,1);
return (_buf1[0] & 0xFF);
}
#endif
private bool nomoreinput = false;
private string ReadZeroTerminatedString()
{
var list = new System.Collections.Generic.List<byte>();
bool done = false;
do
{
// workitem 7740
int n = _stream.Read(_buf1, 0, 1);
if (n != 1)
throw new ZlibException("Unexpected EOF reading GZIP header.");
else
{
if (_buf1[0] == 0)
done = true;
else
list.Add(_buf1[0]);
}
} while (!done);
byte[] a = list.ToArray();
return GZipStream.iso8859dash1.GetString(a, 0, a.Length);
}
private int _ReadAndValidateGzipHeader()
{
int totalBytesRead = 0;
// read the header on the first read
byte[] header = new byte[10];
int n = _stream.Read(header, 0, header.Length);
// workitem 8501: handle edge case (decompress empty stream)
if (n == 0)
return 0;
if (n != 10)
throw new ZlibException("Not a valid GZIP stream.");
if (header[0] != 0x1F || header[1] != 0x8B || header[2] != 8)
throw new ZlibException("Bad GZIP header.");
Int32 timet = BitConverter.ToInt32(header, 4);
_GzipMtime = GZipStream._unixEpoch.AddSeconds(timet);
totalBytesRead += n;
if ((header[3] & 0x04) == 0x04)
{
// read and discard extra field
n = _stream.Read(header, 0, 2); // 2-byte length field
totalBytesRead += n;
Int16 extraLength = (Int16)(header[0] + header[1] * 256);
byte[] extra = new byte[extraLength];
n = _stream.Read(extra, 0, extra.Length);
if (n != extraLength)
throw new ZlibException("Unexpected end-of-file reading GZIP header.");
totalBytesRead += n;
}
if ((header[3] & 0x08) == 0x08)
_GzipFileName = ReadZeroTerminatedString();
if ((header[3] & 0x10) == 0x010)
_GzipComment = ReadZeroTerminatedString();
if ((header[3] & 0x02) == 0x02)
Read(_buf1, 0, 1); // CRC16, ignore
return totalBytesRead;
}
public override System.Int32 Read(System.Byte[] buffer, System.Int32 offset, System.Int32 count)
{
// According to MS documentation, any implementation of the IO.Stream.Read function must:
// (a) throw an exception if offset & count reference an invalid part of the buffer,
// or if count < 0, or if buffer is null
// (b) return 0 only upon EOF, or if count = 0
// (c) if not EOF, then return at least 1 byte, up to <count> bytes
if (_streamMode == StreamMode.Undefined)
{
if (!this._stream.CanRead) throw new ZlibException("The stream is not readable.");
// for the first read, set up some controls.
_streamMode = StreamMode.Reader;
// (The first reference to _z goes through the private accessor which
// may initialize it.)
z.AvailableBytesIn = 0;
if (_flavor == ZlibStreamFlavor.GZIP)
{
_gzipHeaderByteCount = _ReadAndValidateGzipHeader();
// workitem 8501: handle edge case (decompress empty stream)
if (_gzipHeaderByteCount == 0)
return 0;
}
}
if (_streamMode != StreamMode.Reader)
throw new ZlibException("Cannot Read after Writing.");
if (count == 0) return 0;
if (nomoreinput && _wantCompress) return 0; // workitem 8557
if (buffer == null) throw new ArgumentNullException("buffer");
if (count < 0) throw new ArgumentOutOfRangeException("count");
if (offset < buffer.GetLowerBound(0)) throw new ArgumentOutOfRangeException("offset");
if ((offset + count) > buffer.GetLength(0)) throw new ArgumentOutOfRangeException("count");
int rc = 0;
// set up the output of the deflate/inflate codec:
_z.OutputBuffer = buffer;
_z.NextOut = offset;
_z.AvailableBytesOut = count;
// This is necessary in case _workingBuffer has been resized. (new byte[])
// (The first reference to _workingBuffer goes through the private accessor which
// may initialize it.)
_z.InputBuffer = workingBuffer;
do
{
// need data in _workingBuffer in order to deflate/inflate. Here, we check if we have any.
if ((_z.AvailableBytesIn == 0) && (!nomoreinput))
{
// No data available, so try to Read data from the captive stream.
_z.NextIn = 0;
_z.AvailableBytesIn = _stream.Read(_workingBuffer, 0, _workingBuffer.Length);
if (_z.AvailableBytesIn == 0)
nomoreinput = true;
}
// we have data in InputBuffer; now compress or decompress as appropriate
rc = (_wantCompress)
? _z.Deflate(_flushMode)
: _z.Inflate(_flushMode);
if (nomoreinput && (rc == ZlibConstants.Z_BUF_ERROR))
return 0;
if (rc != ZlibConstants.Z_OK && rc != ZlibConstants.Z_STREAM_END)
throw new ZlibException(String.Format("{0}flating: rc={1} msg={2}", (_wantCompress ? "de" : "in"), rc, _z.Message));
if ((nomoreinput || rc == ZlibConstants.Z_STREAM_END) && (_z.AvailableBytesOut == count))
break; // nothing more to read
}
//while (_z.AvailableBytesOut == count && rc == ZlibConstants.Z_OK);
while (_z.AvailableBytesOut > 0 && !nomoreinput && rc == ZlibConstants.Z_OK);
// workitem 8557
// is there more room in output?
if (_z.AvailableBytesOut > 0)
{
if (rc == ZlibConstants.Z_OK && _z.AvailableBytesIn == 0)
{
// deferred
}
// are we completely done reading?
if (nomoreinput)
{
// and in compression?
if (_wantCompress)
{
// no more input data available; therefore we flush to
// try to complete the read
rc = _z.Deflate(FlushType.Finish);
if (rc != ZlibConstants.Z_OK && rc != ZlibConstants.Z_STREAM_END)
throw new ZlibException(String.Format("Deflating: rc={0} msg={1}", rc, _z.Message));
}
}
}
rc = (count - _z.AvailableBytesOut);
// calculate CRC after reading
if (crc != null)
crc.SlurpBlock(buffer, offset, rc);
return rc;
}
public override System.Boolean CanRead
{
get { return this._stream.CanRead; }
}
public override System.Boolean CanSeek
{
get { return this._stream.CanSeek; }
}
public override System.Boolean CanWrite
{
get { return this._stream.CanWrite; }
}
public override System.Int64 Length
{
get { return _stream.Length; }
}
public override long Position
{
get { throw new NotImplementedException(); }
set { throw new NotImplementedException(); }
}
internal enum StreamMode
{
Writer,
Reader,
Undefined,
}
public static void CompressString(String s, Stream compressor)
{
byte[] uncompressed = System.Text.Encoding.UTF8.GetBytes(s);
using (compressor)
{
compressor.Write(uncompressed, 0, uncompressed.Length);
}
}
public static void CompressBuffer(byte[] b, Stream compressor)
{
// workitem 8460
using (compressor)
{
compressor.Write(b, 0, b.Length);
}
}
public static String UncompressString(byte[] compressed, Stream decompressor)
{
// workitem 8460
byte[] working = new byte[1024];
var encoding = System.Text.Encoding.UTF8;
using (var output = new MemoryStream())
{
using (decompressor)
{
int n;
while ((n = decompressor.Read(working, 0, working.Length)) != 0)
{
output.Write(working, 0, n);
}
}
// reset to allow read from start
output.Seek(0, SeekOrigin.Begin);
var sr = new StreamReader(output, encoding);
return sr.ReadToEnd();
}
}
public static byte[] UncompressBuffer(byte[] compressed, Stream decompressor)
{
// workitem 8460
byte[] working = new byte[1024];
using (var output = new MemoryStream())
{
using (decompressor)
{
int n;
while ((n = decompressor.Read(working, 0, working.Length)) != 0)
{
output.Write(working, 0, n);
}
}
return output.ToArray();
}
}
}
}