2 // © Copyright Henrik Ravn 2004
4 // Use, modification and distribution are subject to the Boost Software License, Version 1.0.
5 // (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
10 using System.Runtime.InteropServices;
15 /// Implements a compressed <see cref="Stream"/>, in GZip (.gz) format.
17 public class GZipStream : Stream, IDisposable
20 [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl, CharSet=CharSet.Ansi)]
21 private static extern IntPtr gzopen(string name, string mode);
23 [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
24 private static extern int gzclose(IntPtr gzFile);
26 [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
27 private static extern int gzwrite(IntPtr gzFile, int data, int length);
29 [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
30 private static extern int gzread(IntPtr gzFile, int data, int length);
32 [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
33 private static extern int gzgetc(IntPtr gzFile);
35 [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
36 private static extern int gzputc(IntPtr gzFile, int c);
41 private IntPtr _gzFile;
42 private bool _isDisposed = false;
43 private bool _isWriting;
48 /// Creates a new file as a writeable GZipStream
50 /// <param name="fileName">The name of the compressed file to create</param>
51 /// <param name="level">The compression level to use when adding data</param>
52 /// <exception cref="ZLibException">If an error occurred in the internal zlib function</exception>
53 public GZipStream(string fileName, CompressLevel level)
56 _gzFile = gzopen(fileName, String.Format("wb{0}", (int)level));
57 if (_gzFile == IntPtr.Zero)
58 throw new ZLibException(-1, "Could not open " + fileName);
62 /// Opens an existing file as a readable GZipStream
64 /// <param name="fileName">The name of the file to open</param>
65 /// <exception cref="ZLibException">If an error occurred in the internal zlib function</exception>
66 public GZipStream(string fileName)
69 _gzFile = gzopen(fileName, "rb");
70 if (_gzFile == IntPtr.Zero)
71 throw new ZLibException(-1, "Could not open " + fileName);
76 #region Access properties
78 /// Returns true of this stream can be read from, false otherwise
80 public override bool CanRead
92 public override bool CanSeek
101 /// Returns true if this tsream is writeable, false otherwise
103 public override bool CanWrite
112 #region Destructor & IDispose stuff
115 /// Destroys this instance
123 /// Closes the external file handle
125 public void Dispose()
130 // Does the actual closing of the file handle.
131 private void cleanUp(bool isDisposing)
141 #region Basic reading and writing
143 /// Attempts to read a number of bytes from the stream.
145 /// <param name="buffer">The destination data buffer</param>
146 /// <param name="offset">The index of the first destination byte in <c>buffer</c></param>
147 /// <param name="count">The number of bytes requested</param>
148 /// <returns>The number of bytes read</returns>
149 /// <exception cref="ArgumentNullException">If <c>buffer</c> is null</exception>
150 /// <exception cref="ArgumentOutOfRangeException">If <c>count</c> or <c>offset</c> are negative</exception>
151 /// <exception cref="ArgumentException">If <c>offset</c> + <c>count</c> is > buffer.Length</exception>
152 /// <exception cref="NotSupportedException">If this stream is not readable.</exception>
153 /// <exception cref="ObjectDisposedException">If this stream has been disposed.</exception>
154 public override int Read(byte[] buffer, int offset, int count)
156 if (!CanRead) throw new NotSupportedException();
157 if (buffer == null) throw new ArgumentNullException();
158 if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
159 if ((offset+count) > buffer.Length) throw new ArgumentException();
160 if (_isDisposed) throw new ObjectDisposedException("GZipStream");
162 GCHandle h = GCHandle.Alloc(buffer, GCHandleType.Pinned);
166 result = gzread(_gzFile, h.AddrOfPinnedObject().ToInt32() + offset, count);
168 throw new IOException();
178 /// Attempts to read a single byte from the stream.
180 /// <returns>The byte that was read, or -1 in case of error or End-Of-File</returns>
181 public override int ReadByte()
183 if (!CanRead) throw new NotSupportedException();
184 if (_isDisposed) throw new ObjectDisposedException("GZipStream");
185 return gzgetc(_gzFile);
189 /// Writes a number of bytes to the stream
191 /// <param name="buffer"></param>
192 /// <param name="offset"></param>
193 /// <param name="count"></param>
194 /// <exception cref="ArgumentNullException">If <c>buffer</c> is null</exception>
195 /// <exception cref="ArgumentOutOfRangeException">If <c>count</c> or <c>offset</c> are negative</exception>
196 /// <exception cref="ArgumentException">If <c>offset</c> + <c>count</c> is > buffer.Length</exception>
197 /// <exception cref="NotSupportedException">If this stream is not writeable.</exception>
198 /// <exception cref="ObjectDisposedException">If this stream has been disposed.</exception>
199 public override void Write(byte[] buffer, int offset, int count)
201 if (!CanWrite) throw new NotSupportedException();
202 if (buffer == null) throw new ArgumentNullException();
203 if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
204 if ((offset+count) > buffer.Length) throw new ArgumentException();
205 if (_isDisposed) throw new ObjectDisposedException("GZipStream");
207 GCHandle h = GCHandle.Alloc(buffer, GCHandleType.Pinned);
210 int result = gzwrite(_gzFile, h.AddrOfPinnedObject().ToInt32() + offset, count);
212 throw new IOException();
221 /// Writes a single byte to the stream
223 /// <param name="value">The byte to add to the stream.</param>
224 /// <exception cref="NotSupportedException">If this stream is not writeable.</exception>
225 /// <exception cref="ObjectDisposedException">If this stream has been disposed.</exception>
226 public override void WriteByte(byte value)
228 if (!CanWrite) throw new NotSupportedException();
229 if (_isDisposed) throw new ObjectDisposedException("GZipStream");
231 int result = gzputc(_gzFile, (int)value);
233 throw new IOException();
237 #region Position & length stuff
241 /// <param name="value"></param>
242 /// <exception cref="NotSupportedException">Always thrown</exception>
243 public override void SetLength(long value)
245 throw new NotSupportedException();
251 /// <param name="offset"></param>
252 /// <param name="origin"></param>
253 /// <returns></returns>
254 /// <exception cref="NotSupportedException">Always thrown</exception>
255 public override long Seek(long offset, SeekOrigin origin)
257 throw new NotSupportedException();
261 /// Flushes the <c>GZipStream</c>.
263 /// <remarks>In this implementation, this method does nothing. This is because excessive
264 /// flushing may degrade the achievable compression rates.</remarks>
265 public override void Flush()
267 // left empty on purpose
271 /// Gets/sets the current position in the <c>GZipStream</c>. Not suppported.
273 /// <remarks>In this implementation this property is not supported</remarks>
274 /// <exception cref="NotSupportedException">Always thrown</exception>
275 public override long Position
279 throw new NotSupportedException();
283 throw new NotSupportedException();
288 /// Gets the size of the stream. Not suppported.
290 /// <remarks>In this implementation this property is not supported</remarks>
291 /// <exception cref="NotSupportedException">Always thrown</exception>
292 public override long Length
296 throw new NotSupportedException();