tarinputstream.cs

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// TarInputStream.cs
//
// Copyright (C) 2001 Mike Krueger
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
//
// Linking this library statically or dynamically with other modules is
// making a combined work based on this library.  Thus, the terms and
// conditions of the GNU General Public License cover the whole
// combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent
// modules, and to copy and distribute the resulting executable under
// terms of your choice, provided that you also meet, for each linked
// independent module, the terms and conditions of the license of that
// module.  An independent module is a module which is not derived from
// or based on this library.  If you modify this library, you may extend
// this exception to your version of the library, but you are not
// obligated to do so.  If you do not wish to do so, delete this
// exception statement from your version.

using System;
using System.IO;
using System.Text;

namespace ICSharpCode.SharpZipLib.Tar 
{
	
	/// <summary>
	/// The TarInputStream reads a UNIX tar archive as an InputStream.
	/// methods are provided to position at each successive entry in
	/// the archive, and the read each entry as a normal input stream
	/// using read().
	/// </summary>
	public class TarInputStream : Stream
	{
		/// <summary>
		/// Flag set when last block has been read
		/// </summary>
		protected bool hasHitEOF;
		
		/// <summary>
		/// Size of this entry as recorded in header
		/// </summary>
		protected long entrySize;
		
		/// <summary>
		/// Number of bytes read for this entry so far
		/// </summary>
		protected long entryOffset;

		/// <summary>
		/// Buffer used with calls to <code>Read()</code>
		/// </summary>		
		protected byte[] readBuf;
		
		/// <summary>
		/// Working buffer
		/// </summary>
		protected TarBuffer buffer;
		
		/// <summary>
		/// Current entry being read
		/// </summary>
		protected TarEntry  currEntry;
		
		/// <summary>
		/// Factory used to create TarEntry or descendant class instance
		/// </summary>
		protected IEntryFactory eFactory;
		
		Stream inputStream;

		/// <summary>
		/// Gets a value indicating whether the current stream supports reading
		/// </summary>
		public override bool CanRead {
			get {
				return inputStream.CanRead;
			}
		}
		
		/// <summary>
		/// Gets a value indicating whether the current stream supports seeking
		/// This property always returns false.
		/// </summary>
		public override bool CanSeek {
			get {
				return false;
			}
		}
		
		/// <summary>
		/// Gets a value indicating if the stream supports writing.
		/// This property always returns false.
		/// </summary>
		public override bool CanWrite {
			get {
				return false;
			}
		}
		
		/// <summary>
		/// The length in bytes of the stream
		/// </summary>
		public override long Length {
			get {
				return inputStream.Length;
			}
		}
		
		/// <summary>
		/// Gets or sets the position within the stream. 
		/// Setting the Position is not supported and throws a NotSupportedExceptionNotSupportedException
		/// </summary>
		/// <exception cref="NotSupportedException">Any attempt to set position</exception>
		public override long Position {
			get {
				return inputStream.Position;
			}
			set {
				throw new NotSupportedException("TarInputStream Seek not supported");
			}
		}
		
		/// <summary>
		/// Flushes the baseInputStream
		/// </summary>
		public override void Flush()
		{
			inputStream.Flush();
		}
		
		/// <summary>
		/// Set the streams position.  This operation is not supported and will throw a NotSupportedException
		/// </summary>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override long Seek(long offset, SeekOrigin origin)
		{
			throw new NotSupportedException("TarInputStream Seek not supported");
		}
		
		/// <summary>
		/// Sets the length of the stream
		/// This operation is not supported and will throw a NotSupportedException
		/// </summary>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override void SetLength(long val)
		{
			throw new NotSupportedException("TarInputStream SetLength not supported");
		}
		
		/// <summary>
		/// Writes a block of bytes to this stream using data from a buffer.
		/// This operation is not supported and will throw a NotSupportedException
		/// </summary>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override void Write(byte[] array, int offset, int count)
		{
			throw new NotSupportedException("TarInputStream Write not supported");
		}
		
		/// <summary>
		/// Writes a byte to the current position in the file stream.
		/// This operation is not supported and will throw a NotSupportedException
		/// </summary>
		/// <exception cref="NotSupportedException">Any access</exception>
		public override void WriteByte(byte val)
		{
			throw new NotSupportedException("TarInputStream WriteByte not supported");
		}
			

		/// <summary>
		/// Construct a TarInputStream with default block factor
		/// </summary>
		/// <param name="inputStream">stream to source data from</param>
		public TarInputStream(Stream inputStream) : this(inputStream, TarBuffer.DefaultBlockFactor)
		{
		}

		/// <summary>
		/// Construct a TarInputStream with user specified block factor
		/// </summary>
		/// <param name="inputStream">stream to source data from</param>
		/// <param name="blockFactor">block factor to apply to archive</param>
		public TarInputStream(Stream inputStream, int blockFactor)
		{
			this.inputStream = inputStream;
			this.buffer      = TarBuffer.CreateInputTarBuffer(inputStream, blockFactor);
			
			this.readBuf   = null;
			this.hasHitEOF = false;
			this.eFactory  = null;
		}

		/// <summary>
		/// Set the entry factory for this instance.
		/// </summary>
		/// <param name="factory">The factory for creating new entries</param>
		public void SetEntryFactory(IEntryFactory factory)
		{
			this.eFactory = factory;
		}
		
		/// <summary>
		/// Closes this stream. Calls the TarBuffer's close() method.
		/// The underlying stream is closed by the TarBuffer.
		/// </summary>
		public override void Close()
		{
			this.buffer.Close();
		}
		
		/// <summary>
		/// Get the record size being used by this stream's TarBuffer.
		/// </summary>
		/// <returns>
		/// TarBuffer record size.
		/// </returns>
		public int GetRecordSize()
		{
			return this.buffer.GetRecordSize();
		}
		
		/// <summary>
		/// Get the available data that can be read from the current
		/// entry in the archive. This does not indicate how much data
		/// is left in the entire archive, only in the current entry.
		/// This value is determined from the entry's size header field
		/// and the amount of data already read from the current entry.
		/// </summary>
		/// <returns>
		/// The number of available bytes for the current entry.
		/// </returns>
		public long Available {
			get {
				return this.entrySize - this.entryOffset;
			}
		}
		
		/// <summary>
		/// Skip bytes in the input buffer. This skips bytes in the
		/// current entry's data, not the entire archive, and will
		/// stop at the end of the current entry's data if the number
		/// to skip extends beyond that point.
		/// </summary>
		/// <param name="numToSkip">
		/// The number of bytes to skip.
		/// </param>
		public void Skip(long numToSkip)
		{
			// TODO: REVIEW
			// This is horribly inefficient, but it ensures that we
			// properly skip over bytes via the TarBuffer...
			//
			byte[] skipBuf = new byte[8 * 1024];
			
			for (long num = numToSkip; num > 0;) {
				int toRead = num > skipBuf.Length ? skipBuf.Length : (int)num;
				int numRead = this.Read(skipBuf, 0, toRead);
				
				if (numRead == -1) {
					break;
				}
				
				num -= numRead;
			}
		}
		
		/// <summary>
		/// Since we do not support marking just yet, we return false.
		/// </summary>
		public bool IsMarkSupported {
			get {
				return false;
			}
		}
		
		/// <summary>
		/// Since we do not support marking just yet, we do nothing.
		/// </summary>
		/// <param name ="markLimit">
		/// The limit to mark.
		/// </param>
		public void Mark(int markLimit)
		{
		}
		
		/// <summary>
		/// Since we do not support marking just yet, we do nothing.
		/// </summary>
		public void Reset()
		{
		}
		
		void SkipToNextEntry()
		{
			long numToSkip = this.entrySize - this.entryOffset;
			
			if (numToSkip > 0) {
				this.Skip(numToSkip);
			}
			
			this.readBuf = null;