cannam@89: //
cannam@89: // © Copyright Henrik Ravn 2004
cannam@89: //
cannam@89: // Use, modification and distribution are subject to the Boost Software License, Version 1.0.
cannam@89: // (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
cannam@89: //
cannam@89: 
cannam@89: using System;
cannam@89: using System.IO;
cannam@89: using System.Runtime.InteropServices;
cannam@89: 
cannam@89: namespace DotZLib
cannam@89: {
cannam@89: 	/// <summary>
cannam@89: 	/// Implements a compressed <see cref="Stream"/>, in GZip (.gz) format.
cannam@89: 	/// </summary>
cannam@89: 	public class GZipStream : Stream, IDisposable
cannam@89: 	{
cannam@89:         #region Dll Imports
cannam@89:         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl, CharSet=CharSet.Ansi)]
cannam@89:         private static extern IntPtr gzopen(string name, string mode);
cannam@89: 
cannam@89:         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
cannam@89:         private static extern int gzclose(IntPtr gzFile);
cannam@89: 
cannam@89:         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
cannam@89:         private static extern int gzwrite(IntPtr gzFile, int data, int length);
cannam@89: 
cannam@89:         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
cannam@89:         private static extern int gzread(IntPtr gzFile, int data, int length);
cannam@89: 
cannam@89:         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
cannam@89:         private static extern int gzgetc(IntPtr gzFile);
cannam@89: 
cannam@89:         [DllImport("ZLIB1.dll", CallingConvention=CallingConvention.Cdecl)]
cannam@89:         private static extern int gzputc(IntPtr gzFile, int c);
cannam@89: 
cannam@89:         #endregion
cannam@89: 
cannam@89:         #region Private data
cannam@89:         private IntPtr _gzFile;
cannam@89:         private bool _isDisposed = false;
cannam@89:         private bool _isWriting;
cannam@89:         #endregion
cannam@89: 
cannam@89:         #region Constructors
cannam@89:         /// <summary>
cannam@89:         /// Creates a new file as a writeable GZipStream
cannam@89:         /// </summary>
cannam@89:         /// <param name="fileName">The name of the compressed file to create</param>
cannam@89:         /// <param name="level">The compression level to use when adding data</param>
cannam@89:         /// <exception cref="ZLibException">If an error occurred in the internal zlib function</exception>
cannam@89: 		public GZipStream(string fileName, CompressLevel level)
cannam@89: 		{
cannam@89:             _isWriting = true;
cannam@89:             _gzFile = gzopen(fileName, String.Format("wb{0}", (int)level));
cannam@89:             if (_gzFile == IntPtr.Zero)
cannam@89:                 throw new ZLibException(-1, "Could not open " + fileName);
cannam@89: 		}
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Opens an existing file as a readable GZipStream
cannam@89:         /// </summary>
cannam@89:         /// <param name="fileName">The name of the file to open</param>
cannam@89:         /// <exception cref="ZLibException">If an error occurred in the internal zlib function</exception>
cannam@89:         public GZipStream(string fileName)
cannam@89:         {
cannam@89:             _isWriting = false;
cannam@89:             _gzFile = gzopen(fileName, "rb");
cannam@89:             if (_gzFile == IntPtr.Zero)
cannam@89:                 throw new ZLibException(-1, "Could not open " + fileName);
cannam@89: 
cannam@89:         }
cannam@89:         #endregion
cannam@89: 
cannam@89:         #region Access properties
cannam@89:         /// <summary>
cannam@89:         /// Returns true of this stream can be read from, false otherwise
cannam@89:         /// </summary>
cannam@89:         public override bool CanRead
cannam@89:         {
cannam@89:             get
cannam@89:             {
cannam@89:                 return !_isWriting;
cannam@89:             }
cannam@89:         }
cannam@89: 
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Returns false.
cannam@89:         /// </summary>
cannam@89:         public override bool CanSeek
cannam@89:         {
cannam@89:             get
cannam@89:             {
cannam@89:                 return false;
cannam@89:             }
cannam@89:         }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Returns true if this tsream is writeable, false otherwise
cannam@89:         /// </summary>
cannam@89:         public override bool CanWrite
cannam@89:         {
cannam@89:             get
cannam@89:             {
cannam@89:                 return _isWriting;
cannam@89:             }
cannam@89:         }
cannam@89:         #endregion
cannam@89: 
cannam@89:         #region Destructor & IDispose stuff
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Destroys this instance
cannam@89:         /// </summary>
cannam@89:         ~GZipStream()
cannam@89:         {
cannam@89:             cleanUp(false);
cannam@89:         }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Closes the external file handle
cannam@89:         /// </summary>
cannam@89:         public void Dispose()
cannam@89:         {
cannam@89:             cleanUp(true);
cannam@89:         }
cannam@89: 
cannam@89:         // Does the actual closing of the file handle.
cannam@89:         private void cleanUp(bool isDisposing)
cannam@89:         {
cannam@89:             if (!_isDisposed)
cannam@89:             {
cannam@89:                 gzclose(_gzFile);
cannam@89:                 _isDisposed = true;
cannam@89:             }
cannam@89:         }
cannam@89:         #endregion
cannam@89: 
cannam@89:         #region Basic reading and writing
cannam@89:         /// <summary>
cannam@89:         /// Attempts to read a number of bytes from the stream.
cannam@89:         /// </summary>
cannam@89:         /// <param name="buffer">The destination data buffer</param>
cannam@89:         /// <param name="offset">The index of the first destination byte in <c>buffer</c></param>
cannam@89:         /// <param name="count">The number of bytes requested</param>
cannam@89:         /// <returns>The number of bytes read</returns>
cannam@89:         /// <exception cref="ArgumentNullException">If <c>buffer</c> is null</exception>
cannam@89:         /// <exception cref="ArgumentOutOfRangeException">If <c>count</c> or <c>offset</c> are negative</exception>
cannam@89:         /// <exception cref="ArgumentException">If <c>offset</c>  + <c>count</c> is &gt; buffer.Length</exception>
cannam@89:         /// <exception cref="NotSupportedException">If this stream is not readable.</exception>
cannam@89:         /// <exception cref="ObjectDisposedException">If this stream has been disposed.</exception>
cannam@89:         public override int Read(byte[] buffer, int offset, int count)
cannam@89:         {
cannam@89:             if (!CanRead) throw new NotSupportedException();
cannam@89:             if (buffer == null) throw new ArgumentNullException();
cannam@89:             if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
cannam@89:             if ((offset+count) > buffer.Length) throw new ArgumentException();
cannam@89:             if (_isDisposed) throw new ObjectDisposedException("GZipStream");
cannam@89: 
cannam@89:             GCHandle h = GCHandle.Alloc(buffer, GCHandleType.Pinned);
cannam@89:             int result;
cannam@89:             try
cannam@89:             {
cannam@89:                 result = gzread(_gzFile, h.AddrOfPinnedObject().ToInt32() + offset, count);
cannam@89:                 if (result < 0)
cannam@89:                     throw new IOException();
cannam@89:             }
cannam@89:             finally
cannam@89:             {
cannam@89:                 h.Free();
cannam@89:             }
cannam@89:             return result;
cannam@89:         }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Attempts to read a single byte from the stream.
cannam@89:         /// </summary>
cannam@89:         /// <returns>The byte that was read, or -1 in case of error or End-Of-File</returns>
cannam@89:         public override int ReadByte()
cannam@89:         {
cannam@89:             if (!CanRead) throw new NotSupportedException();
cannam@89:             if (_isDisposed) throw new ObjectDisposedException("GZipStream");
cannam@89:             return gzgetc(_gzFile);
cannam@89:         }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Writes a number of bytes to the stream
cannam@89:         /// </summary>
cannam@89:         /// <param name="buffer"></param>
cannam@89:         /// <param name="offset"></param>
cannam@89:         /// <param name="count"></param>
cannam@89:         /// <exception cref="ArgumentNullException">If <c>buffer</c> is null</exception>
cannam@89:         /// <exception cref="ArgumentOutOfRangeException">If <c>count</c> or <c>offset</c> are negative</exception>
cannam@89:         /// <exception cref="ArgumentException">If <c>offset</c>  + <c>count</c> is &gt; buffer.Length</exception>
cannam@89:         /// <exception cref="NotSupportedException">If this stream is not writeable.</exception>
cannam@89:         /// <exception cref="ObjectDisposedException">If this stream has been disposed.</exception>
cannam@89:         public override void Write(byte[] buffer, int offset, int count)
cannam@89:         {
cannam@89:             if (!CanWrite) throw new NotSupportedException();
cannam@89:             if (buffer == null) throw new ArgumentNullException();
cannam@89:             if (offset < 0 || count < 0) throw new ArgumentOutOfRangeException();
cannam@89:             if ((offset+count) > buffer.Length) throw new ArgumentException();
cannam@89:             if (_isDisposed) throw new ObjectDisposedException("GZipStream");
cannam@89: 
cannam@89:             GCHandle h = GCHandle.Alloc(buffer, GCHandleType.Pinned);
cannam@89:             try
cannam@89:             {
cannam@89:                 int result = gzwrite(_gzFile, h.AddrOfPinnedObject().ToInt32() + offset, count);
cannam@89:                 if (result < 0)
cannam@89:                     throw new IOException();
cannam@89:             }
cannam@89:             finally
cannam@89:             {
cannam@89:                 h.Free();
cannam@89:             }
cannam@89:         }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Writes a single byte to the stream
cannam@89:         /// </summary>
cannam@89:         /// <param name="value">The byte to add to the stream.</param>
cannam@89:         /// <exception cref="NotSupportedException">If this stream is not writeable.</exception>
cannam@89:         /// <exception cref="ObjectDisposedException">If this stream has been disposed.</exception>
cannam@89:         public override void WriteByte(byte value)
cannam@89:         {
cannam@89:             if (!CanWrite) throw new NotSupportedException();
cannam@89:             if (_isDisposed) throw new ObjectDisposedException("GZipStream");
cannam@89: 
cannam@89:             int result = gzputc(_gzFile, (int)value);
cannam@89:             if (result < 0)
cannam@89:                 throw new IOException();
cannam@89:         }
cannam@89:         #endregion
cannam@89: 
cannam@89:         #region Position & length stuff
cannam@89:         /// <summary>
cannam@89:         /// Not supported.
cannam@89:         /// </summary>
cannam@89:         /// <param name="value"></param>
cannam@89:         /// <exception cref="NotSupportedException">Always thrown</exception>
cannam@89:         public override void SetLength(long value)
cannam@89:         {
cannam@89:             throw new NotSupportedException();
cannam@89:         }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         ///  Not suppported.
cannam@89:         /// </summary>
cannam@89:         /// <param name="offset"></param>
cannam@89:         /// <param name="origin"></param>
cannam@89:         /// <returns></returns>
cannam@89:         /// <exception cref="NotSupportedException">Always thrown</exception>
cannam@89:         public override long Seek(long offset, SeekOrigin origin)
cannam@89:         {
cannam@89:             throw new NotSupportedException();
cannam@89:         }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Flushes the <c>GZipStream</c>.
cannam@89:         /// </summary>
cannam@89:         /// <remarks>In this implementation, this method does nothing. This is because excessive
cannam@89:         /// flushing may degrade the achievable compression rates.</remarks>
cannam@89:         public override void Flush()
cannam@89:         {
cannam@89:             // left empty on purpose
cannam@89:         }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Gets/sets the current position in the <c>GZipStream</c>. Not suppported.
cannam@89:         /// </summary>
cannam@89:         /// <remarks>In this implementation this property is not supported</remarks>
cannam@89:         /// <exception cref="NotSupportedException">Always thrown</exception>
cannam@89:         public override long Position
cannam@89:         {
cannam@89:             get
cannam@89:             {
cannam@89:                 throw new NotSupportedException();
cannam@89:             }
cannam@89:             set
cannam@89:             {
cannam@89:                 throw new NotSupportedException();
cannam@89:             }
cannam@89:         }
cannam@89: 
cannam@89:         /// <summary>
cannam@89:         /// Gets the size of the stream. Not suppported.
cannam@89:         /// </summary>
cannam@89:         /// <remarks>In this implementation this property is not supported</remarks>
cannam@89:         /// <exception cref="NotSupportedException">Always thrown</exception>
cannam@89:         public override long Length
cannam@89:         {
cannam@89:             get
cannam@89:             {
cannam@89:                 throw new NotSupportedException();
cannam@89:             }
cannam@89:         }
cannam@89:         #endregion
cannam@89:     }
cannam@89: }