Ejemplo n.º 1
0
 /// <summary>
 /// Resets the inflater so that a new stream can be decompressed.  All
 /// pending input and output will be discarded.
 /// </summary>
 public void Reset()
 {
     mode     = noHeader ? DECODE_BLOCKS : DECODE_HEADER;
     totalIn  = 0;
     totalOut = 0;
     input.Reset();
     outputWindow.Reset();
     dynHeader   = null;
     litlenTree  = null;
     distTree    = null;
     isLastBlock = false;
     adler.Reset();
 }
		/// <summary>
		/// Decodes the deflated stream.
		/// </summary>
		/// <returns>
		/// false if more input is needed, or if finished.
		/// </returns>
		/// <exception cref="SharpZipBaseException">
		/// if deflated stream is invalid.
		/// </exception>
		private bool Decode()
		{
			switch (mode) {
				case DECODE_HEADER:
					return DecodeHeader();

				case DECODE_DICT:
					return DecodeDict();

				case DECODE_CHKSUM:
					return DecodeChksum();
				
				case DECODE_BLOCKS:
					if (isLastBlock) {
						if (noHeader) {
							mode = FINISHED;
							return false;
						} else {
							input.SkipToByteBoundary();
							neededBits = 32;
							mode = DECODE_CHKSUM;
							return true;
						}
					}
					
					int type = input.PeekBits(3);
					if (type < 0) {
						return false;
					}
					input.DropBits(3);
					
					if ((type & 1) != 0) {
						isLastBlock = true;
					}
					switch (type >> 1){
						case DeflaterConstants.STORED_BLOCK:
							input.SkipToByteBoundary();
							mode = DECODE_STORED_LEN1;
							break;
						case DeflaterConstants.STATIC_TREES:
							litlenTree = InflaterHuffmanTree.defLitLenTree;
							distTree = InflaterHuffmanTree.defDistTree;
							mode = DECODE_HUFFMAN;
							break;
						case DeflaterConstants.DYN_TREES:
							dynHeader = new InflaterDynHeader();
							mode = DECODE_DYN_HEADER;
							break;
						default:
							throw new SharpZipBaseException("Unknown block type " + type);
					}
					return true;
				
				case DECODE_STORED_LEN1: 
				{
					if ((uncomprLen = input.PeekBits(16)) < 0) {
						return false;
					}
					input.DropBits(16);
					mode = DECODE_STORED_LEN2;
				}
					goto case DECODE_STORED_LEN2; // fall through
					
				case DECODE_STORED_LEN2: 
				{
					int nlen = input.PeekBits(16);
					if (nlen < 0) {
						return false;
					}
					input.DropBits(16);
					if (nlen != (uncomprLen ^ 0xffff)) {
						throw new SharpZipBaseException("broken uncompressed block");
					}
					mode = DECODE_STORED;
				}
					goto case DECODE_STORED; // fall through
					
				case DECODE_STORED: 
				{
					int more = outputWindow.CopyStored(input, uncomprLen);
					uncomprLen -= more;
					if (uncomprLen == 0) {
						mode = DECODE_BLOCKS;
						return true;
					}
					return !input.IsNeedingInput;
				}
				
				case DECODE_DYN_HEADER:
					if (!dynHeader.Decode(input)) {
						return false;
					}
					
					litlenTree = dynHeader.BuildLitLenTree();
					distTree = dynHeader.BuildDistTree();
					mode = DECODE_HUFFMAN;
					goto case DECODE_HUFFMAN; // fall through
					
				case DECODE_HUFFMAN:
				case DECODE_HUFFMAN_LENBITS:
				case DECODE_HUFFMAN_DIST:
				case DECODE_HUFFMAN_DISTBITS:
					return DecodeHuffman();
				
				case FINISHED:
					return false;
				
				default:
					throw new SharpZipBaseException("Inflater.Decode unknown mode");
			}
		}
		/// <summary>
		/// Resets the inflater so that a new stream can be decompressed.  All
		/// pending input and output will be discarded.
		/// </summary>
		public void Reset()
		{
			mode = noHeader ? DECODE_BLOCKS : DECODE_HEADER;
			totalIn = 0;
			totalOut = 0;
			input.Reset();
			outputWindow.Reset();
			dynHeader = null;
			litlenTree = null;
			distTree = null;
			isLastBlock = false;
			adler.Reset();
		}
Ejemplo n.º 4
0
        /// <summary>
        /// Decodes the deflated stream.
        /// </summary>
        /// <returns>
        /// false if more input is needed, or if finished.
        /// </returns>
        /// <exception cref="SharpZipBaseException">
        /// if deflated stream is invalid.
        /// </exception>
        private bool Decode()
        {
            switch (mode)
            {
            case DECODE_HEADER:
                return(DecodeHeader());

            case DECODE_DICT:
                return(DecodeDict());

            case DECODE_CHKSUM:
                return(DecodeChksum());

            case DECODE_BLOCKS:
                if (isLastBlock)
                {
                    if (noHeader)
                    {
                        mode = FINISHED;
                        return(false);
                    }
                    else
                    {
                        input.SkipToByteBoundary();
                        neededBits = 32;
                        mode       = DECODE_CHKSUM;
                        return(true);
                    }
                }

                int type = input.PeekBits(3);
                if (type < 0)
                {
                    return(false);
                }
                input.DropBits(3);

                if ((type & 1) != 0)
                {
                    isLastBlock = true;
                }
                switch (type >> 1)
                {
                case DeflaterConstants.STORED_BLOCK:
                    input.SkipToByteBoundary();
                    mode = DECODE_STORED_LEN1;
                    break;

                case DeflaterConstants.STATIC_TREES:
                    litlenTree = InflaterHuffmanTree.defLitLenTree;
                    distTree   = InflaterHuffmanTree.defDistTree;
                    mode       = DECODE_HUFFMAN;
                    break;

                case DeflaterConstants.DYN_TREES:
                    dynHeader = new InflaterDynHeader();
                    mode      = DECODE_DYN_HEADER;
                    break;

                default:
                    throw new SharpZipBaseException("Unknown block type " + type);
                }
                return(true);

            case DECODE_STORED_LEN1:
            {
                if ((uncomprLen = input.PeekBits(16)) < 0)
                {
                    return(false);
                }
                input.DropBits(16);
                mode = DECODE_STORED_LEN2;
            }
                goto case DECODE_STORED_LEN2;                         // fall through

            case DECODE_STORED_LEN2:
            {
                int nlen = input.PeekBits(16);
                if (nlen < 0)
                {
                    return(false);
                }
                input.DropBits(16);
                if (nlen != (uncomprLen ^ 0xffff))
                {
                    throw new SharpZipBaseException("broken uncompressed block");
                }
                mode = DECODE_STORED;
            }
                goto case DECODE_STORED;                         // fall through

            case DECODE_STORED:
            {
                int more = outputWindow.CopyStored(input, uncomprLen);
                uncomprLen -= more;
                if (uncomprLen == 0)
                {
                    mode = DECODE_BLOCKS;
                    return(true);
                }
                return(!input.IsNeedingInput);
            }

            case DECODE_DYN_HEADER:
                if (!dynHeader.Decode(input))
                {
                    return(false);
                }

                litlenTree = dynHeader.BuildLitLenTree();
                distTree   = dynHeader.BuildDistTree();
                mode       = DECODE_HUFFMAN;
                goto case DECODE_HUFFMAN;                         // fall through

            case DECODE_HUFFMAN:
            case DECODE_HUFFMAN_LENBITS:
            case DECODE_HUFFMAN_DIST:
            case DECODE_HUFFMAN_DISTBITS:
                return(DecodeHuffman());

            case FINISHED:
                return(false);

            default:
                throw new SharpZipBaseException("Inflater.Decode unknown mode");
            }
        }