[1096] | 1 | //
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| 2 | // © Copyright Henrik Ravn 2004
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| 3 | //
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| 4 | // Use, modification and distribution are subject to the Boost Software License, Version 1.0.
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| 5 | // (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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| 6 | //
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| 7 |
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| 8 | using System;
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| 9 | using System.IO;
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| 10 | using System.Runtime.InteropServices;
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| 11 |
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| 12 | namespace DotZLib
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| 13 | {
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| 14 | /// <summary>
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| 15 | /// Implements a compressed <see cref="Stream"/>, in GZip (.gz) format.
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| 16 | /// </summary>
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| 17 | public class GZipStream : Stream, IDisposable
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| 18 | {
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| 19 | #region Dll Imports
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| 20 | [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl, CharSet=CharSet.Ansi)]
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| 21 | private static extern IntPtr gzopen(string name, string mode);
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| 22 |
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| 23 | [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
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| 24 | private static extern int gzclose(IntPtr gzFile);
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| 25 |
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| 26 | [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
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| 27 | private static extern int gzwrite(IntPtr gzFile, int data, int length);
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| 28 |
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| 29 | [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
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| 30 | private static extern int gzread(IntPtr gzFile, int data, int length);
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| 31 |
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| 32 | [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
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| 33 | private static extern int gzgetc(IntPtr gzFile);
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| 34 |
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| 35 | [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
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| 36 | private static extern int gzputc(IntPtr gzFile, int c);
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| 37 |
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| 38 | #endregion
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| 39 |
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| 40 | #region Private data
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| 41 | private IntPtr _gzFile;
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| 42 | private bool _isDisposed = false;
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| 43 | private bool _isWriting;
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| 44 | #endregion
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| 45 |
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| 46 | #region Constructors
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| 47 | /// <summary>
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| 48 | /// Creates a new file as a writeable GZipStream
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| 49 | /// </summary>
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| 50 | /// <param name="fileName">The name of the compressed file to create</param>
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| 51 | /// <param name="level">The compression level to use when adding data</param>
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| 52 | /// <exception cref="ZLibException">If an error occurred in the internal zlib function</exception>
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| 53 | public GZipStream(string fileName, CompressLevel level)
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| 54 | {
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| 55 | _isWriting = true;
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| 56 | _gzFile = gzopen(fileName, String.Format("wb{0}", (int)level));
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| 57 | if (_gzFile == IntPtr.Zero)
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| 58 | throw new ZLibException(-1, "Could not open " + fileName);
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| 59 | }
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| 60 |
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| 61 | /// <summary>
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| 62 | /// Opens an existing file as a readable GZipStream
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| 63 | /// </summary>
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| 64 | /// <param name="fileName">The name of the file to open</param>
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| 65 | /// <exception cref="ZLibException">If an error occurred in the internal zlib function</exception>
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| 66 | public GZipStream(string fileName)
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| 67 | {
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| 68 | _isWriting = false;
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| 69 | _gzFile = gzopen(fileName, "rb");
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| 70 | if (_gzFile == IntPtr.Zero)
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| 71 | throw new ZLibException(-1, "Could not open " + fileName);
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| 72 |
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| 73 | }
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| 74 | #endregion
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| 75 |
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| 76 | #region Access properties
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| 77 | /// <summary>
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| 78 | /// Returns true of this stream can be read from, false otherwise
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| 79 | /// </summary>
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| 80 | public override bool CanRead
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| 81 | {
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| 82 | get
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| 83 | {
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| 84 | return !_isWriting;
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| 85 | }
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| 86 | }
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| 87 |
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| 88 |
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| 89 | /// <summary>
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| 90 | /// Returns false.
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| 91 | /// </summary>
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| 92 | public override bool CanSeek
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| 93 | {
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| 94 | get
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| 95 | {
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| 96 | return false;
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| 97 | }
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| 98 | }
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| 99 |
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| 100 | /// <summary>
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| 101 | /// Returns true if this tsream is writeable, false otherwise
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| 102 | /// </summary>
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| 103 | public override bool CanWrite
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| 104 | {
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| 105 | get
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| 106 | {
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| 107 | return _isWriting;
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| 108 | }
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| 109 | }
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| 110 | #endregion
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| 111 |
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| 112 | #region Destructor & IDispose stuff
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| 113 |
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| 114 | /// <summary>
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| 115 | /// Destroys this instance
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| 116 | /// </summary>
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| 117 | ~GZipStream()
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| 118 | {
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| 119 | cleanUp(false);
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| 120 | }
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| 121 |
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| 122 | /// <summary>
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| 123 | /// Closes the external file handle
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| 124 | /// </summary>
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| 125 | public void Dispose()
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| 126 | {
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| 127 | cleanUp(true);
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| 128 | }
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| 129 |
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| 130 | // Does the actual closing of the file handle.
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| 131 | private void cleanUp(bool isDisposing)
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| 132 | {
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| 133 | if (!_isDisposed)
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| 134 | {
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| 135 | gzclose(_gzFile);
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| 136 | _isDisposed = true;
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| 137 | }
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| 138 | }
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| 139 | #endregion
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| 140 |
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| 141 | #region Basic reading and writing
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| 142 | /// <summary>
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| 143 | /// Attempts to read a number of bytes from the stream.
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| 144 | /// </summary>
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| 145 | /// <param name="buffer">The destination data buffer</param>
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| 146 | /// <param name="offset">The index of the first destination byte in <c>buffer</c></param>
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| 147 | /// <param name="count">The number of bytes requested</param>
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| 148 | /// <returns>The number of bytes read</returns>
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| 149 | /// <exception cref="ArgumentNullException">If <c>buffer</c> is null</exception>
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| 150 | /// <exception cref="ArgumentOutOfRangeException">If <c>count</c> or <c>offset</c> are negative</exception>
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| 151 | /// <exception cref="ArgumentException">If <c>offset</c> + <c>count</c> is > buffer.Length</exception>
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| 152 | /// <exception cref="NotSupportedException">If this stream is not readable.</exception>
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| 153 | /// <exception cref="ObjectDisposedException">If this stream has been disposed.</exception>
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| 154 | public override int Read(byte[] buffer, int offset, int count)
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| 155 | {
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| 156 | if (!CanRead) throw new NotSupportedException();
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| 157 | if (buffer == null) throw new ArgumentNullException();
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| 158 | if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
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| 159 | if ((offset+count) > buffer.Length) throw new ArgumentException();
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| 160 | if (_isDisposed) throw new ObjectDisposedException("GZipStream");
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| 161 |
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| 162 | GCHandle h = GCHandle.Alloc(buffer, GCHandleType.Pinned);
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| 163 | int result;
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| 164 | try
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| 165 | {
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| 166 | result = gzread(_gzFile, h.AddrOfPinnedObject().ToInt32() + offset, count);
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| 167 | if (result < 0)
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| 168 | throw new IOException();
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| 169 | }
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| 170 | finally
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| 171 | {
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| 172 | h.Free();
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| 173 | }
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| 174 | return result;
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| 175 | }
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| 176 |
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| 177 | /// <summary>
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| 178 | /// Attempts to read a single byte from the stream.
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| 179 | /// </summary>
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| 180 | /// <returns>The byte that was read, or -1 in case of error or End-Of-File</returns>
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| 181 | public override int ReadByte()
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| 182 | {
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| 183 | if (!CanRead) throw new NotSupportedException();
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| 184 | if (_isDisposed) throw new ObjectDisposedException("GZipStream");
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| 185 | return gzgetc(_gzFile);
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| 186 | }
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| 187 |
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| 188 | /// <summary>
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| 189 | /// Writes a number of bytes to the stream
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| 190 | /// </summary>
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| 191 | /// <param name="buffer"></param>
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| 192 | /// <param name="offset"></param>
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| 193 | /// <param name="count"></param>
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| 194 | /// <exception cref="ArgumentNullException">If <c>buffer</c> is null</exception>
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| 195 | /// <exception cref="ArgumentOutOfRangeException">If <c>count</c> or <c>offset</c> are negative</exception>
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| 196 | /// <exception cref="ArgumentException">If <c>offset</c> + <c>count</c> is > buffer.Length</exception>
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| 197 | /// <exception cref="NotSupportedException">If this stream is not writeable.</exception>
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| 198 | /// <exception cref="ObjectDisposedException">If this stream has been disposed.</exception>
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| 199 | public override void Write(byte[] buffer, int offset, int count)
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| 200 | {
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| 201 | if (!CanWrite) throw new NotSupportedException();
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| 202 | if (buffer == null) throw new ArgumentNullException();
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| 203 | if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
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| 204 | if ((offset+count) > buffer.Length) throw new ArgumentException();
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| 205 | if (_isDisposed) throw new ObjectDisposedException("GZipStream");
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| 206 |
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| 207 | GCHandle h = GCHandle.Alloc(buffer, GCHandleType.Pinned);
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| 208 | try
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| 209 | {
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| 210 | int result = gzwrite(_gzFile, h.AddrOfPinnedObject().ToInt32() + offset, count);
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| 211 | if (result < 0)
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| 212 | throw new IOException();
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| 213 | }
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| 214 | finally
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| 215 | {
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| 216 | h.Free();
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| 217 | }
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| 218 | }
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| 219 |
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| 220 | /// <summary>
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| 221 | /// Writes a single byte to the stream
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| 222 | /// </summary>
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| 223 | /// <param name="value">The byte to add to the stream.</param>
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| 224 | /// <exception cref="NotSupportedException">If this stream is not writeable.</exception>
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| 225 | /// <exception cref="ObjectDisposedException">If this stream has been disposed.</exception>
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| 226 | public override void WriteByte(byte value)
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| 227 | {
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| 228 | if (!CanWrite) throw new NotSupportedException();
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| 229 | if (_isDisposed) throw new ObjectDisposedException("GZipStream");
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| 230 |
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| 231 | int result = gzputc(_gzFile, (int)value);
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| 232 | if (result < 0)
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| 233 | throw new IOException();
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| 234 | }
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| 235 | #endregion
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| 236 |
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| 237 | #region Position & length stuff
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| 238 | /// <summary>
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| 239 | /// Not supported.
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| 240 | /// </summary>
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| 241 | /// <param name="value"></param>
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| 242 | /// <exception cref="NotSupportedException">Always thrown</exception>
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| 243 | public override void SetLength(long value)
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| 244 | {
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| 245 | throw new NotSupportedException();
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| 246 | }
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| 247 |
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| 248 | /// <summary>
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| 249 | /// Not suppported.
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| 250 | /// </summary>
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| 251 | /// <param name="offset"></param>
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| 252 | /// <param name="origin"></param>
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| 253 | /// <returns></returns>
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| 254 | /// <exception cref="NotSupportedException">Always thrown</exception>
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| 255 | public override long Seek(long offset, SeekOrigin origin)
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| 256 | {
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| 257 | throw new NotSupportedException();
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| 258 | }
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| 259 |
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| 260 | /// <summary>
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| 261 | /// Flushes the <c>GZipStream</c>.
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| 262 | /// </summary>
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| 263 | /// <remarks>In this implementation, this method does nothing. This is because excessive
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| 264 | /// flushing may degrade the achievable compression rates.</remarks>
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| 265 | public override void Flush()
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| 266 | {
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| 267 | // left empty on purpose
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| 268 | }
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| 269 |
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| 270 | /// <summary>
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| 271 | /// Gets/sets the current position in the <c>GZipStream</c>. Not suppported.
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| 272 | /// </summary>
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| 273 | /// <remarks>In this implementation this property is not supported</remarks>
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| 274 | /// <exception cref="NotSupportedException">Always thrown</exception>
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| 275 | public override long Position
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| 276 | {
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| 277 | get
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| 278 | {
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| 279 | throw new NotSupportedException();
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| 280 | }
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| 281 | set
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| 282 | {
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| 283 | throw new NotSupportedException();
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| 284 | }
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| 285 | }
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| 286 |
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| 287 | /// <summary>
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| 288 | /// Gets the size of the stream. Not suppported.
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| 289 | /// </summary>
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| 290 | /// <remarks>In this implementation this property is not supported</remarks>
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| 291 | /// <exception cref="NotSupportedException">Always thrown</exception>
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| 292 | public override long Length
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| 293 | {
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| 294 | get
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| 295 | {
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| 296 | throw new NotSupportedException();
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| 297 | }
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| 298 | }
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| 299 | #endregion
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| 300 | }
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| 301 | }
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