zipinputstream.cs

C#开发的QQ,希望大家喜欢.献给大家作参考

		{
			if (inputBuffer.ReadLeInt() != ZipConstants.EXTSIG) {
				throw new ZipException("Data descriptor signature not found");
			}
			
			entry.Crc = inputBuffer.ReadLeInt() & 0xFFFFFFFFL;
			csize = inputBuffer.ReadLeInt();
			size = inputBuffer.ReadLeInt();
			
			entry.Size = size & 0xFFFFFFFFL;
			entry.CompressedSize = csize & 0xFFFFFFFFL;
		}
		
		/// <summary>
		/// Closes the current zip entry and moves to the next one.
		/// </summary>
		/// <exception cref="InvalidOperationException">
		/// The stream is closed
		/// </exception>
		/// <exception cref="ZipException">
		/// The Zip stream ends early
		/// </exception>
		public void CloseEntry()
		{
			if (crc == null) {
				throw new InvalidOperationException("Closed.");
			}
			
			if (entry == null) {
				return;
			}
			
			if (method == (int)CompressionMethod.Deflated) {
				if ((flags & 8) != 0) {
					// We don't know how much we must skip, read until end.
					byte[] tmp = new byte[2048];
					while (Read(tmp, 0, tmp.Length) > 0)
						;
					// read will close this entry
					return;
				}
				csize -= inf.TotalIn;
				inputBuffer.Available -= inf.RemainingInput;	
			}

			if (inputBuffer.Available > csize && csize >= 0) {
				inputBuffer.Available = (int)((long)inputBuffer.Available - csize);
			} else {
				csize -= inputBuffer.Available;
				inputBuffer.Available = 0;
				while (csize != 0) {
					int skipped = (int)base.Skip(csize & 0xFFFFFFFFL);
					
					if (skipped <= 0) {
						throw new ZipException("Zip archive ends early.");
					}
					
					csize -= skipped;
				}
			}
			
			size = 0;
			crc.Reset();
			if (method == (int)CompressionMethod.Deflated) {
				inf.Reset();
			}
			entry = null;
		}
		
		/// <summary>
		/// Returns 1 if there is an entry available
		/// Otherwise returns 0.
		/// </summary>
		public override int Available {
			get {
				return entry != null ? 1 : 0;
			}
		}
		
		/// <summary>
		/// Reads a byte from the current zip entry.
		/// </summary>
		/// <returns>
		/// The byte or -1 if end of stream is reached.
		/// </returns>
		/// <exception name="System.IO.IOException">
		/// An i/o error occured.
		/// </exception>
		/// <exception name="ICSharpCode.SharpZipLib.ZipException">
		/// The deflated stream is corrupted.
		/// </exception>
		public override int ReadByte()
		{
			byte[] b = new byte[1];
			if (Read(b, 0, 1) <= 0) {
				return -1;
			}
			return b[0] & 0xff;
		}

		// Perform the initial read on an entry which may include 
		// reading encryption headers and setting up inflation.
		int InitialRead(byte[] destination, int offset, int count)
		{
			if (entry.Version > ZipConstants.VERSION_MADE_BY) {
				throw new ZipException("Libray cannot extract this entry version required (" + entry.Version.ToString() + ")");
			}
			
			// test for encryption
			if (entry.IsCrypted) {
		
				if (password == null) {
					throw new ZipException("No password set.");
				}
			
				// Generate and set crypto transform...
				PkzipClassicManaged managed = new PkzipClassicManaged();
				byte[] key = PkzipClassic.GenerateKeys(Encoding.ASCII.GetBytes(password));
					
				inputBuffer.CryptoTransform = managed.CreateDecryptor(key, null);
			
				byte[] cryptbuffer = new byte[ZipConstants.CRYPTO_HEADER_SIZE];
				inputBuffer.ReadClearTextBuffer(cryptbuffer, 0, ZipConstants.CRYPTO_HEADER_SIZE);
					
				if ((flags & 8) == 0) {
					if (cryptbuffer[ZipConstants.CRYPTO_HEADER_SIZE - 1] != (byte)(entry.Crc >> 24)) {
						throw new ZipException("Invalid password");
					}
				}
				else {
					if (cryptbuffer[ZipConstants.CRYPTO_HEADER_SIZE - 1] != (byte)((entry.DosTime >> 8) & 0xff)) {
						throw new ZipException("Invalid password");
					}
				}
					
				if (csize >= ZipConstants.CRYPTO_HEADER_SIZE) {
					csize -= ZipConstants.CRYPTO_HEADER_SIZE;
				}
			} 
			else {
				inputBuffer.CryptoTransform = null;
			}
			
			if (method == (int)CompressionMethod.Deflated && inputBuffer.Available > 0) {
				inputBuffer.SetInflaterInput(inf);
			}
			
			internalReader = new ReaderDelegate(BodyRead);
			return BodyRead(destination, offset, count);
		}
		

		/// <summary>
		/// Read a block of bytes from the stream.
		/// </summary>
		/// <param name="destination">The destination for the bytes.</param>
		/// <param name="index">The index to start storing data.</param>
		/// <param name="count">The number of bytes to attempt to read.</param>
		/// <returns>Returns the number of bytes read.</returns>
		/// <remarks>Zero bytes read means end of stream.</remarks>
		public override int Read(byte[] destination, int index, int count)
		{
			return internalReader(destination, index, count);
		}

		/// <summary>
		/// Reads a block of bytes from the current zip entry.
		/// </summary>
		/// <returns>
		/// The number of bytes read (this may be less than the length requested, even before the end of stream), or 0 on end of stream.
		/// </returns>
		/// <exception name="IOException">
		/// An i/o error occured.
		/// </exception>
		/// <exception cref="ZipException">
		/// The deflated stream is corrupted.
		/// </exception>
		/// <exception cref="InvalidOperationException">
		/// The stream is not open.
		/// </exception>
		public int BodyRead(byte[] b, int off, int len)
		{
			if (crc == null) {
				throw new InvalidOperationException("Closed.");
			}
			
			if (entry == null || len <= 0 ) {
				return 0;
			}
			
			bool finished = false;
			
			switch (method) {
				case (int)CompressionMethod.Deflated:
					len = base.Read(b, off, len);
					if (len <= 0) {
						if (!inf.IsFinished) {
							throw new ZipException("Inflater not finished!?");
						}
						inputBuffer.Available = inf.RemainingInput;
						
						if ((flags & 8) == 0 && (inf.TotalIn != csize || inf.TotalOut != size)) {
							throw new ZipException("size mismatch: " + csize + ";" + size + " <-> " + inf.TotalIn + ";" + inf.TotalOut);
						}
						inf.Reset();
						finished = true;
					}
					break;
				
				case (int)CompressionMethod.Stored:
					if (len > csize && csize >= 0) {
						len = (int)csize;
					}
					len = inputBuffer.ReadClearTextBuffer(b, off, len);
					if (len > 0) {
						csize -= len;
						size -= len;
					}
					
					if (csize == 0) {
						finished = true;
					} else {
						if (len < 0) {
							throw new ZipException("EOF in stored block");
						}
					}
					break;
			}
				
			if (len > 0) {
				crc.Update(b, off, len);
			}
			
			if (finished) {
				StopDecrypting();
				
				if ((flags & 8) != 0) {
					ReadDataDescriptor();
				}
				
				if ((crc.Value & 0xFFFFFFFFL) != entry.Crc && entry.Crc != -1) {
					throw new ZipException("CRC mismatch");
				}
				crc.Reset();
				entry = null;
			}
			return len;
		}

		/// <summary>
		/// Closes the zip input stream
		/// </summary>
		public override void Close()
		{
			base.Close();
			crc = null;
			entry = null;
		}
	}
}