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// GZipStream.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-08 18:14:39>
//
// ------------------------------------------------------------------
//
// This module defines the GZipStream class, which can be used as a replacement for
// the System.IO.Compression.GZipStream class in the .NET BCL. NB: The design is not
// completely OO clean: there is some intelligence in the ZlibBaseStream that reads the
// GZip header.
//
// ------------------------------------------------------------------
using System;
using System.IO;
namespace OfficeOpenXml.Packaging.Ionic.Zlib
{
/// <summary>
/// A class for compressing and decompressing GZIP streams.
/// </summary>
/// <remarks>
///
/// <para>
/// The <c>GZipStream</c> is a <see
/// href="http://en.wikipedia.org/wiki/Decorator_pattern">Decorator</see> on a
/// <see cref="Stream"/>. It adds GZIP compression or decompression to any
/// stream.
/// </para>
///
/// <para>
/// Like the <c>System.IO.Compression.GZipStream</c> in the .NET Base Class Library, the
/// <c>Ionic.Zlib.GZipStream</c> can compress while writing, or decompress while
/// reading, but not vice versa. The compression method used is GZIP, which is
/// documented in <see href="http://www.ietf.org/rfc/rfc1952.txt">IETF RFC
/// 1952</see>, "GZIP file format specification version 4.3".</para>
///
/// <para>
/// A <c>GZipStream</c> can be used to decompress data (through <c>Read()</c>) or
/// to compress data (through <c>Write()</c>), but not both.
/// </para>
///
/// <para>
/// If you wish to use the <c>GZipStream</c> to compress data, you must wrap it
/// around a write-able stream. As you call <c>Write()</c> on the <c>GZipStream</c>, the
/// data will be compressed into the GZIP format. If you want to decompress data,
/// you must wrap the <c>GZipStream</c> around a readable stream that contains an
/// IETF RFC 1952-compliant stream. The data will be decompressed as you call
/// <c>Read()</c> on the <c>GZipStream</c>.
/// </para>
///
/// <para>
/// Though the GZIP format allows data from multiple files to be concatenated
/// together, this stream handles only a single segment of GZIP format, typically
/// representing a single file.
/// </para>
///
/// <para>
/// This class is similar to <see cref="ZlibStream"/> and <see cref="DeflateStream"/>.
/// <c>ZlibStream</c> handles RFC1950-compliant streams. <see cref="DeflateStream"/>
/// handles RFC1951-compliant streams. This class handles RFC1952-compliant streams.
/// </para>
///
/// </remarks>
///
/// <seealso cref="DeflateStream" />
/// <seealso cref="ZlibStream" />
public class GZipStream : System.IO.Stream
{
// GZip format
// source: http://tools.ietf.org/html/rfc1952
//
// header id: 2 bytes 1F 8B
// compress method 1 byte 8= DEFLATE (none other supported)
// flag 1 byte bitfield (See below)
// mtime 4 bytes time_t (seconds since jan 1, 1970 UTC of the file.
// xflg 1 byte 2 = max compress used , 4 = max speed (can be ignored)
// OS 1 byte OS for originating archive. set to 0xFF in compression.
// extra field length 2 bytes optional - only if FEXTRA is set.
// extra field varies
// filename varies optional - if FNAME is set. zero terminated. ISO-8859-1.
// file comment varies optional - if FCOMMENT is set. zero terminated. ISO-8859-1.
// crc16 1 byte optional - present only if FHCRC bit is set
// compressed data varies
// CRC32 4 bytes
// isize 4 bytes data size modulo 2^32
//
// FLG (FLaGs)
// bit 0 FTEXT - indicates file is ASCII text (can be safely ignored)
// bit 1 FHCRC - there is a CRC16 for the header immediately following the header
// bit 2 FEXTRA - extra fields are present
// bit 3 FNAME - the zero-terminated filename is present. encoding; ISO-8859-1.
// bit 4 FCOMMENT - a zero-terminated file comment is present. encoding: ISO-8859-1
// bit 5 reserved
// bit 6 reserved
// bit 7 reserved
//
// On consumption:
// Extra field is a bunch of nonsense and can be safely ignored.
// Header CRC and OS, likewise.
//
// on generation:
// all optional fields get 0, except for the OS, which gets 255.
//
/// <summary>
/// The comment on the GZIP stream.
/// </summary>
///
/// <remarks>
/// <para>
/// The GZIP format allows for each file to optionally have an associated
/// comment stored with the file. The comment is encoded with the ISO-8859-1
/// code page. To include a comment in a GZIP stream you create, set this
/// property before calling <c>Write()</c> for the first time on the
/// <c>GZipStream</c>.
/// </para>
///
/// <para>
/// When using <c>GZipStream</c> to decompress, you can retrieve this property
/// after the first call to <c>Read()</c>. If no comment has been set in the
/// GZIP bytestream, the Comment property will return <c>null</c>
/// (<c>Nothing</c> in VB).
/// </para>
/// </remarks>
public String Comment
{
get
{
return _Comment;
}
set
{
if (_disposed) throw new ObjectDisposedException("GZipStream");
_Comment = value;
}
}
/// <summary>
/// The FileName for the GZIP stream.
/// </summary>
///
/// <remarks>
///
/// <para>
/// The GZIP format optionally allows each file to have an associated
/// filename. When compressing data (through <c>Write()</c>), set this
/// FileName before calling <c>Write()</c> the first time on the <c>GZipStream</c>.
/// The actual filename is encoded into the GZIP bytestream with the
/// ISO-8859-1 code page, according to RFC 1952. It is the application's
/// responsibility to insure that the FileName can be encoded and decoded
/// correctly with this code page.
/// </para>
///
/// <para>
/// When decompressing (through <c>Read()</c>), you can retrieve this value
/// any time after the first <c>Read()</c>. In the case where there was no filename
/// encoded into the GZIP bytestream, the property will return <c>null</c> (<c>Nothing</c>
/// in VB).
/// </para>
/// </remarks>
public String FileName
{
get { return _FileName; }
set
{
if (_disposed) throw new ObjectDisposedException("GZipStream");
_FileName = value;
if (_FileName == null) return;
if (_FileName.IndexOf("/") != -1)
{
_FileName = _FileName.Replace("/", "\\");
}
if (_FileName.EndsWith("\\"))
throw new Exception("Illegal filename");
if (_FileName.IndexOf("\\") != -1)
{
// trim any leading path
_FileName = Path.GetFileName(_FileName);
}
}
}
/// <summary>
/// The last modified time for the GZIP stream.
/// </summary>
///
/// <remarks>
/// GZIP allows the storage of a last modified time with each GZIP entry.
/// When compressing data, you can set this before the first call to
/// <c>Write()</c>. When decompressing, you can retrieve this value any time
/// after the first call to <c>Read()</c>.
/// </remarks>
public DateTime? LastModified;
/// <summary>
/// The CRC on the GZIP stream.
/// </summary>
/// <remarks>
/// This is used for internal error checking. You probably don't need to look at this property.
/// </remarks>
public int Crc32 { get { return _Crc32; } }
private int _headerByteCount;
internal ZlibBaseStream _baseStream;
bool _disposed;
bool _firstReadDone;
string _FileName;
string _Comment;
int _Crc32;
/// <summary>
/// Create a <c>GZipStream</c> using the specified <c>CompressionMode</c>.
/// </summary>
/// <remarks>
///
/// <para>
/// When mode is <c>CompressionMode.Compress</c>, the <c>GZipStream</c> will use the
/// default compression level.
/// </para>
///
/// <para>
/// As noted in the class documentation, the <c>CompressionMode</c> (Compress
/// or Decompress) also establishes the "direction" of the stream. A
/// <c>GZipStream</c> with <c>CompressionMode.Compress</c> works only through
/// <c>Write()</c>. A <c>GZipStream</c> with
/// <c>CompressionMode.Decompress</c> works only through <c>Read()</c>.
/// </para>
///
/// </remarks>
///
/// <example>
/// This example shows how to use a GZipStream to compress data.
/// <code>
/// using (System.IO.Stream input = System.IO.File.OpenRead(fileToCompress))
/// {
/// using (var raw = System.IO.File.Create(outputFile))
/// {
/// using (Stream compressor = new GZipStream(raw, CompressionMode.Compress))
/// {
/// byte[] buffer = new byte[WORKING_BUFFER_SIZE];
/// int n;
/// while ((n= input.Read(buffer, 0, buffer.Length)) != 0)
/// {
/// compressor.Write(buffer, 0, n);
/// }
/// }
/// }
/// }
/// </code>
/// <code lang="VB">
/// Dim outputFile As String = (fileToCompress &amp; ".compressed")
/// Using input As Stream = File.OpenRead(fileToCompress)
/// Using raw As FileStream = File.Create(outputFile)
/// Using compressor As Stream = New GZipStream(raw, CompressionMode.Compress)
/// Dim buffer As Byte() = New Byte(4096) {}
/// Dim n As Integer = -1
/// Do While (n &lt;&gt; 0)
/// If (n &gt; 0) Then
/// compressor.Write(buffer, 0, n)
/// End If
/// n = input.Read(buffer, 0, buffer.Length)
/// Loop
/// End Using
/// End Using
/// End Using
/// </code>
/// </example>
///
/// <example>
/// This example shows how to use a GZipStream to uncompress a file.
/// <code>
/// private void GunZipFile(string filename)
/// {
/// if (!filename.EndsWith(".gz))
/// throw new ArgumentException("filename");
/// var DecompressedFile = filename.Substring(0,filename.Length-3);
/// byte[] working = new byte[WORKING_BUFFER_SIZE];
/// int n= 1;
/// using (System.IO.Stream input = System.IO.File.OpenRead(filename))
/// {
/// using (Stream decompressor= new Ionic.Zlib.GZipStream(input, CompressionMode.Decompress, true))
/// {
/// using (var output = System.IO.File.Create(DecompressedFile))
/// {
/// while (n !=0)
/// {
/// n= decompressor.Read(working, 0, working.Length);
/// if (n > 0)
/// {
/// output.Write(working, 0, n);
/// }
/// }
/// }
/// }
/// }
/// }
/// </code>
///
/// <code lang="VB">
/// Private Sub GunZipFile(ByVal filename as String)
/// If Not (filename.EndsWith(".gz)) Then
/// Throw New ArgumentException("filename")
/// End If
/// Dim DecompressedFile as String = filename.Substring(0,filename.Length-3)
/// Dim working(WORKING_BUFFER_SIZE) as Byte
/// Dim n As Integer = 1
/// Using input As Stream = File.OpenRead(filename)
/// Using decompressor As Stream = new Ionic.Zlib.GZipStream(input, CompressionMode.Decompress, True)
/// Using output As Stream = File.Create(UncompressedFile)
/// Do
/// n= decompressor.Read(working, 0, working.Length)
/// If n > 0 Then
/// output.Write(working, 0, n)
/// End IF
/// Loop While (n > 0)
/// End Using
/// End Using
/// End Using
/// End Sub
/// </code>
/// </example>
///
/// <param name="stream">The stream which will be read or written.</param>
/// <param name="mode">Indicates whether the GZipStream will compress or decompress.</param>
public GZipStream(Stream stream, CompressionMode mode)
: this(stream, mode, CompressionLevel.Default, false)
{
}
/// <summary>
/// Create a <c>GZipStream</c> using the specified <c>CompressionMode</c> and
/// the specified <c>CompressionLevel</c>.
/// </summary>
/// <remarks>
///
/// <para>
/// The <c>CompressionMode</c> (Compress or Decompress) also establishes the
/// "direction" of the stream. A <c>GZipStream</c> with
/// <c>CompressionMode.Compress</c> works only through <c>Write()</c>. A
/// <c>GZipStream</c> with <c>CompressionMode.Decompress</c> works only
/// through <c>Read()</c>.
/// </para>
///
/// </remarks>
///
/// <example>
///
/// This example shows how to use a <c>GZipStream</c> to compress a file into a .gz file.
///
/// <code>
/// using (System.IO.Stream input = System.IO.File.OpenRead(fileToCompress))
/// {
/// using (var raw = System.IO.File.Create(fileToCompress + ".gz"))
/// {
/// using (Stream compressor = new GZipStream(raw,
/// CompressionMode.Compress,
/// CompressionLevel.BestCompression))
/// {
/// byte[] buffer = new byte[WORKING_BUFFER_SIZE];
/// int n;
/// while ((n= input.Read(buffer, 0, buffer.Length)) != 0)
/// {
/// compressor.Write(buffer, 0, n);
/// }
/// }
/// }
/// }
/// </code>
///
/// <code lang="VB">
/// Using input As Stream = File.OpenRead(fileToCompress)
/// Using raw As FileStream = File.Create(fileToCompress &amp; ".gz")
/// Using compressor As Stream = New GZipStream(raw, CompressionMode.Compress, CompressionLevel.BestCompression)
/// Dim buffer As Byte() = New Byte(4096) {}
/// Dim n As Integer = -1
/// Do While (n &lt;&gt; 0)
/// If (n &gt; 0) Then
/// compressor.Write(buffer, 0, n)
/// End If
/// n = input.Read(buffer, 0, buffer.Length)
/// Loop
/// End Using
/// End Using
/// End Using
/// </code>
/// </example>
/// <param name="stream">The stream to be read or written while deflating or inflating.</param>
/// <param name="mode">Indicates whether the <c>GZipStream</c> will compress or decompress.</param>
/// <param name="level">A tuning knob to trade speed for effectiveness.</param>
public GZipStream(Stream stream, CompressionMode mode, CompressionLevel level)
: this(stream, mode, level, false)
{
}
/// <summary>
/// Create a <c>GZipStream</c> using the specified <c>CompressionMode</c>, and
/// explicitly specify whether the stream should be left open after Deflation
/// or Inflation.
/// </summary>
///
/// <remarks>
/// <para>
/// This constructor allows the application to request that the captive stream
/// remain open after the deflation or inflation occurs. By default, after
/// <c>Close()</c> is called on the stream, the captive stream is also
/// closed. In some cases this is not desired, for example if the stream is a
/// memory stream that will be re-read after compressed data has been written
/// to it. Specify true for the <paramref name="leaveOpen"/> parameter to leave
/// the stream open.
/// </para>
///
/// <para>
/// The <see cref="CompressionMode"/> (Compress or Decompress) also
/// establishes the "direction" of the stream. A <c>GZipStream</c> with
/// <c>CompressionMode.Compress</c> works only through <c>Write()</c>. A <c>GZipStream</c>
/// with <c>CompressionMode.Decompress</c> works only through <c>Read()</c>.
/// </para>
///
/// <para>
/// The <c>GZipStream</c> will use the default compression level. If you want
/// to specify the compression level, see <see cref="GZipStream(Stream,
/// CompressionMode, CompressionLevel, bool)"/>.
/// </para>
///
/// <para>
/// See the other overloads of this constructor for example code.
/// </para>
///
/// </remarks>
///
/// <param name="stream">
/// The stream which will be read or written. This is called the "captive"
/// stream in other places in this documentation.
/// </param>
///
/// <param name="mode">Indicates whether the GZipStream will compress or decompress.
/// </param>
///
/// <param name="leaveOpen">
/// true if the application would like the base stream to remain open after
/// inflation/deflation.
/// </param>
public GZipStream(Stream stream, CompressionMode mode, bool leaveOpen)
: this(stream, mode, CompressionLevel.Default, leaveOpen)
{
}
/// <summary>
/// Create a <c>GZipStream</c> using the specified <c>CompressionMode</c> and the
/// specified <c>CompressionLevel</c>, and explicitly specify whether the
/// stream should be left open after Deflation or Inflation.
/// </summary>
///
/// <remarks>
///
/// <para>
/// This constructor allows the application to request that the captive stream
/// remain open after the deflation or inflation occurs. By default, after
/// <c>Close()</c> is called on the stream, the captive stream is also
/// closed. In some cases this is not desired, for example if the stream is a
/// memory stream that will be re-read after compressed data has been written
/// to it. Specify true for the <paramref name="leaveOpen"/> parameter to
/// leave the stream open.
/// </para>
///
/// <para>
/// As noted in the class documentation, the <c>CompressionMode</c> (Compress
/// or Decompress) also establishes the "direction" of the stream. A
/// <c>GZipStream</c> with <c>CompressionMode.Compress</c> works only through
/// <c>Write()</c>. A <c>GZipStream</c> with <c>CompressionMode.Decompress</c> works only
/// through <c>Read()</c>.
/// </para>
///
/// </remarks>
///
/// <example>
/// This example shows how to use a <c>GZipStream</c> to compress data.
/// <code>
/// using (System.IO.Stream input = System.IO.File.OpenRead(fileToCompress))
/// {
/// using (var raw = System.IO.File.Create(outputFile))
/// {
/// using (Stream compressor = new GZipStream(raw, CompressionMode.Compress, CompressionLevel.BestCompression, true))
/// {
/// byte[] buffer = new byte[WORKING_BUFFER_SIZE];
/// int n;
/// while ((n= input.Read(buffer, 0, buffer.Length)) != 0)
/// {
/// compressor.Write(buffer, 0, n);
/// }
/// }
/// }
/// }
/// </code>
/// <code lang="VB">
/// Dim outputFile As String = (fileToCompress &amp; ".compressed")
/// Using input As Stream = File.OpenRead(fileToCompress)
/// Using raw As FileStream = File.Create(outputFile)
/// Using compressor As Stream = New GZipStream(raw, CompressionMode.Compress, CompressionLevel.BestCompression, True)
/// Dim buffer As Byte() = New Byte(4096) {}
/// Dim n As Integer = -1
/// Do While (n &lt;&gt; 0)
/// If (n &gt; 0) Then
/// compressor.Write(buffer, 0, n)
/// End If
/// n = input.Read(buffer, 0, buffer.Length)
/// Loop
/// End Using
/// End Using
/// End Using
/// </code>
/// </example>
/// <param name="stream">The stream which will be read or written.</param>
/// <param name="mode">Indicates whether the GZipStream will compress or decompress.</param>
/// <param name="leaveOpen">true if the application would like the stream to remain open after inflation/deflation.</param>
/// <param name="level">A tuning knob to trade speed for effectiveness.</param>
public GZipStream(Stream stream, CompressionMode mode, CompressionLevel level, bool leaveOpen)
{
_baseStream = new ZlibBaseStream(stream, mode, level, ZlibStreamFlavor.GZIP, leaveOpen);
}
#region Zlib properties
/// <summary>
/// This property sets the flush behavior on the stream.
/// </summary>
virtual public FlushType FlushMode
{
get { return (this._baseStream._flushMode); }
set {
if (_disposed) throw new ObjectDisposedException("GZipStream");
this._baseStream._flushMode = value;
}
}
/// <summary>
/// The size of the working buffer for the compression codec.
/// </summary>
///
/// <remarks>
/// <para>
/// The working buffer is used for all stream operations. The default size is
/// 1024 bytes. The minimum size is 128 bytes. You may get better performance
/// with a larger buffer. Then again, you might not. You would have to test
/// it.
/// </para>
///
/// <para>
/// Set this before the first call to <c>Read()</c> or <c>Write()</c> on the
/// stream. If you try to set it afterwards, it will throw.
/// </para>
/// </remarks>
public int BufferSize
{
get
{
return this._baseStream._bufferSize;
}
set
{
if (_disposed) throw new ObjectDisposedException("GZipStream");
if (this._baseStream._workingBuffer != null)
throw new ZlibException("The working buffer is already set.");
if (value < ZlibConstants.WorkingBufferSizeMin)
throw new ZlibException(String.Format("Don't be silly. {0} bytes?? Use a bigger buffer, at least {1}.", value, ZlibConstants.WorkingBufferSizeMin));
this._baseStream._bufferSize = value;
}
}
/// <summary> Returns the total number of bytes input so far.</summary>
virtual public long TotalIn
{
get
{
return this._baseStream._z.TotalBytesIn;
}
}
/// <summary> Returns the total number of bytes output so far.</summary>
virtual public long TotalOut
{
get
{
return this._baseStream._z.TotalBytesOut;
}
}
#endregion
#region Stream methods
/// <summary>
/// Dispose the stream.
/// </summary>
/// <remarks>
/// <para>
/// This may or may not result in a <c>Close()</c> call on the captive
/// stream. See the constructors that have a <c>leaveOpen</c> parameter
/// for more information.
/// </para>
/// <para>
/// This method may be invoked in two distinct scenarios. If disposing
/// == true, the method has been called directly or indirectly by a
/// user's code, for example via the public Dispose() method. In this
/// case, both managed and unmanaged resources can be referenced and
/// disposed. If disposing == false, the method has been called by the
/// runtime from inside the object finalizer and this method should not
/// reference other objects; in that case only unmanaged resources must
/// be referenced or disposed.
/// </para>
/// </remarks>
/// <param name="disposing">
/// indicates whether the Dispose method was invoked by user code.
/// </param>
protected override void Dispose(bool disposing)
{
try
{
if (!_disposed)
{
if (disposing && (this._baseStream != null))
{
this._baseStream.Close();
this._Crc32 = _baseStream.Crc32;
}
_disposed = true;
}
}
finally
{
base.Dispose(disposing);
}
}
/// <summary>
/// Indicates whether the stream can be read.
/// </summary>
/// <remarks>
/// The return value depends on whether the captive stream supports reading.
/// </remarks>
public override bool CanRead
{
get
{
if (_disposed) throw new ObjectDisposedException("GZipStream");
return _baseStream._stream.CanRead;
}
}
/// <summary>
/// Indicates whether the stream supports Seek operations.
/// </summary>
/// <remarks>
/// Always returns false.
/// </remarks>
public override bool CanSeek
{
get { return false; }
}
/// <summary>
/// Indicates whether the stream can be written.
/// </summary>
/// <remarks>
/// The return value depends on whether the captive stream supports writing.
/// </remarks>
public override bool CanWrite
{
get
{
if (_disposed) throw new ObjectDisposedException("GZipStream");
return _baseStream._stream.CanWrite;
}
}
/// <summary>
/// Flush the stream.
/// </summary>
public override void Flush()
{
if (_disposed) throw new ObjectDisposedException("GZipStream");
_baseStream.Flush();
}
/// <summary>
/// Reading this property always throws a <see cref="NotImplementedException"/>.
/// </summary>
public override long Length
{
get { throw new NotImplementedException(); }
}
/// <summary>
/// The position of the stream pointer.
/// </summary>
///
/// <remarks>
/// Setting this property always throws a <see
/// cref="NotImplementedException"/>. Reading will return the total bytes
/// written out, if used in writing, or the total bytes read in, if used in
/// reading. The count may refer to compressed bytes or uncompressed bytes,
/// depending on how you've used the stream.
/// </remarks>
public override long Position
{
get
{
if (this._baseStream._streamMode == Ionic.Zlib.ZlibBaseStream.StreamMode.Writer)
return this._baseStream._z.TotalBytesOut + _headerByteCount;
if (this._baseStream._streamMode == Ionic.Zlib.ZlibBaseStream.StreamMode.Reader)
return this._baseStream._z.TotalBytesIn + this._baseStream._gzipHeaderByteCount;
return 0;
}
set { throw new NotImplementedException(); }
}
/// <summary>
/// Read and decompress data from the source stream.
/// </summary>
///
/// <remarks>
/// With a <c>GZipStream</c>, decompression is done through reading.
/// </remarks>
///
/// <example>
/// <code>
/// byte[] working = new byte[WORKING_BUFFER_SIZE];
/// using (System.IO.Stream input = System.IO.File.OpenRead(_CompressedFile))
/// {
/// using (Stream decompressor= new Ionic.Zlib.GZipStream(input, CompressionMode.Decompress, true))
/// {
/// using (var output = System.IO.File.Create(_DecompressedFile))
/// {
/// int n;
/// while ((n= decompressor.Read(working, 0, working.Length)) !=0)
/// {
/// output.Write(working, 0, n);
/// }
/// }
/// }
/// }
/// </code>
/// </example>
/// <param name="buffer">The buffer into which the decompressed data should be placed.</param>
/// <param name="offset">the offset within that data array to put the first byte read.</param>
/// <param name="count">the number of bytes to read.</param>
/// <returns>the number of bytes actually read</returns>
public override int Read(byte[] buffer, int offset, int count)
{
if (_disposed) throw new ObjectDisposedException("GZipStream");
int n = _baseStream.Read(buffer, offset, count);
// Console.WriteLine("GZipStream::Read(buffer, off({0}), c({1}) = {2}", offset, count, n);
// Console.WriteLine( Util.FormatByteArray(buffer, offset, n) );
if (!_firstReadDone)
{
_firstReadDone = true;
FileName = _baseStream._GzipFileName;
Comment = _baseStream._GzipComment;
}
return n;
}
/// <summary>
/// Calling this method always throws a <see cref="NotImplementedException"/>.
/// </summary>
/// <param name="offset">irrelevant; it will always throw!</param>
/// <param name="origin">irrelevant; it will always throw!</param>
/// <returns>irrelevant!</returns>
public override long Seek(long offset, SeekOrigin origin)
{
throw new NotImplementedException();
}
/// <summary>
/// Calling this method always throws a <see cref="NotImplementedException"/>.
/// </summary>
/// <param name="value">irrelevant; this method will always throw!</param>
public override void SetLength(long value)
{
throw new NotImplementedException();
}
/// <summary>
/// Write data to the stream.
/// </summary>
///
/// <remarks>
/// <para>
/// If you wish to use the <c>GZipStream</c> to compress data while writing,
/// you can create a <c>GZipStream</c> with <c>CompressionMode.Compress</c>, and a
/// writable output stream. Then call <c>Write()</c> on that <c>GZipStream</c>,
/// providing uncompressed data as input. The data sent to the output stream
/// will be the compressed form of the data written.
/// </para>
///
/// <para>
/// A <c>GZipStream</c> can be used for <c>Read()</c> or <c>Write()</c>, but not
/// both. Writing implies compression. Reading implies decompression.
/// </para>
///
/// </remarks>
/// <param name="buffer">The buffer holding data to write to the stream.</param>
/// <param name="offset">the offset within that data array to find the first byte to write.</param>
/// <param name="count">the number of bytes to write.</param>
public override void Write(byte[] buffer, int offset, int count)
{
if (_disposed) throw new ObjectDisposedException("GZipStream");
if (_baseStream._streamMode == Ionic.Zlib.ZlibBaseStream.StreamMode.Undefined)
{
//Console.WriteLine("GZipStream: First write");
if (_baseStream._wantCompress)
{
// first write in compression, therefore, emit the GZIP header
_headerByteCount = EmitHeader();
}
else
{
throw new InvalidOperationException();
}
}
_baseStream.Write(buffer, offset, count);
}
#endregion
internal static readonly System.DateTime _unixEpoch = new System.DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
#if SILVERLIGHT || NETCF
internal static readonly System.Text.Encoding iso8859dash1 = new Ionic.Encoding.Iso8859Dash1Encoding();
#else
internal static readonly System.Text.Encoding iso8859dash1 = System.Text.Encoding.GetEncoding("iso-8859-1");
#endif
private int EmitHeader()
{
byte[] commentBytes = (Comment == null) ? null : iso8859dash1.GetBytes(Comment);
byte[] filenameBytes = (FileName == null) ? null : iso8859dash1.GetBytes(FileName);
int cbLength = (Comment == null) ? 0 : commentBytes.Length + 1;
int fnLength = (FileName == null) ? 0 : filenameBytes.Length + 1;
int bufferLength = 10 + cbLength + fnLength;
byte[] header = new byte[bufferLength];
int i = 0;
// ID
header[i++] = 0x1F;
header[i++] = 0x8B;
// compression method
header[i++] = 8;
byte flag = 0;
if (Comment != null)
flag ^= 0x10;
if (FileName != null)
flag ^= 0x8;
// flag
header[i++] = flag;
// mtime
if (!LastModified.HasValue) LastModified = DateTime.Now;
System.TimeSpan delta = LastModified.Value - _unixEpoch;
Int32 timet = (Int32)delta.TotalSeconds;
Array.Copy(BitConverter.GetBytes(timet), 0, header, i, 4);
i += 4;
// xflg
header[i++] = 0; // this field is totally useless
// OS
header[i++] = 0xFF; // 0xFF == unspecified
// extra field length - only if FEXTRA is set, which it is not.
//header[i++]= 0;
//header[i++]= 0;
// filename
if (fnLength != 0)
{
Array.Copy(filenameBytes, 0, header, i, fnLength - 1);
i += fnLength - 1;
header[i++] = 0; // terminate
}
// comment
if (cbLength != 0)
{
Array.Copy(commentBytes, 0, header, i, cbLength - 1);
i += cbLength - 1;
header[i++] = 0; // terminate
}
_baseStream._stream.Write(header, 0, header.Length);
return header.Length; // bytes written
}
/// <summary>
/// Compress a string into a byte array using GZip.
/// </summary>
///
/// <remarks>
/// Uncompress it with <see cref="GZipStream.UncompressString(byte[])"/>.
/// </remarks>
///
/// <seealso cref="GZipStream.UncompressString(byte[])"/>
/// <seealso cref="GZipStream.CompressBuffer(byte[])"/>
///
/// <param name="s">
/// A string to compress. The string will first be encoded
/// using UTF8, then compressed.
/// </param>
///
/// <returns>The string in compressed form</returns>
public static byte[] CompressString(String s)
{
using (var ms = new MemoryStream())
{
System.IO.Stream compressor =
new GZipStream(ms, CompressionMode.Compress, CompressionLevel.BestCompression);
ZlibBaseStream.CompressString(s, compressor);
return ms.ToArray();
}
}
/// <summary>
/// Compress a byte array into a new byte array using GZip.
/// </summary>
///
/// <remarks>
/// Uncompress it with <see cref="GZipStream.UncompressBuffer(byte[])"/>.
/// </remarks>
///
/// <seealso cref="GZipStream.CompressString(string)"/>
/// <seealso cref="GZipStream.UncompressBuffer(byte[])"/>
///
/// <param name="b">
/// A buffer to compress.
/// </param>
///
/// <returns>The data in compressed form</returns>
public static byte[] CompressBuffer(byte[] b)
{
using (var ms = new MemoryStream())
{
System.IO.Stream compressor =
new GZipStream( ms, CompressionMode.Compress, CompressionLevel.BestCompression );
ZlibBaseStream.CompressBuffer(b, compressor);
return ms.ToArray();
}
}
/// <summary>
/// Uncompress a GZip'ed byte array into a single string.
/// </summary>
///
/// <seealso cref="GZipStream.CompressString(String)"/>
/// <seealso cref="GZipStream.UncompressBuffer(byte[])"/>
///
/// <param name="compressed">
/// A buffer containing GZIP-compressed data.
/// </param>
///
/// <returns>The uncompressed string</returns>
public static String UncompressString(byte[] compressed)
{
using (var input = new MemoryStream(compressed))
{
Stream decompressor = new GZipStream(input, CompressionMode.Decompress);
return ZlibBaseStream.UncompressString(compressed, decompressor);
}
}
/// <summary>
/// Uncompress a GZip'ed byte array into a byte array.
/// </summary>
///
/// <seealso cref="GZipStream.CompressBuffer(byte[])"/>
/// <seealso cref="GZipStream.UncompressString(byte[])"/>
///
/// <param name="compressed">
/// A buffer containing data that has been compressed with GZip.
/// </param>
///
/// <returns>The data in uncompressed form</returns>
public static byte[] UncompressBuffer(byte[] compressed)
{
using (var input = new System.IO.MemoryStream(compressed))
{
System.IO.Stream decompressor =
new GZipStream( input, CompressionMode.Decompress );
return ZlibBaseStream.UncompressBuffer(compressed, decompressor);
}
}
}
}