File size: 4,682 Bytes
fab29d7 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 |
// Copyright (c) Dr. Dirk Lellinger. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using SlobViewer.Common;
namespace SlobViewer.Slob
{
public class StoreItemBase
{
protected string[] _content;
protected byte[] _compressedContent;
protected byte[] _contentIds;
protected void DecompressContent(Encoding encoding, string compressionMethod, byte[] buffer)
{
Func<Stream, Stream> createInflaterStream = null;
switch (compressionMethod)
{
case "lzma":
case "lzma2":
{
createInflaterStream = (inStream) =>
{
var outStream = new MemoryStream();
int iDictionaryByte = 30;
int dictionarySize = iDictionaryByte == 40 ? -1 : (2 + iDictionaryByte % 2) << (11 + iDictionaryByte / 2);
inStream.Read(buffer, 0, 6); // Read 6 header bytes. currently, we do not know exactly what those header bytes mean. Seems that byte[5] is the encoding prop, and byte[3] and [4] the compressed length
byte[] properties = new byte[5];
properties[0] = buffer[5];
Array.Copy(BitConverter.GetBytes(dictionarySize), 0, properties, 1, 4); // copy dictionary size into array
var decoder = new SevenZip.Compression.LZMA.Decoder();
decoder.SetDecoderProperties(properties);
long outSize = long.MaxValue;
long compressedSize = inStream.Length - inStream.Position;
decoder.Code(inStream, outStream, compressedSize, outSize, null);
outStream.Seek(0, SeekOrigin.Begin);
return outStream;
};
DecompressWithInflaterStream(createInflaterStream, encoding, buffer);
}
break;
case "zlib":
createInflaterStream = (s) => new ICSharpCode.SharpZipLib.Zip.Compression.Streams.InflaterInputStream(s);
DecompressWithInflaterStream(createInflaterStream, encoding, buffer);
break;
case "bz2":
case "bzip2":
createInflaterStream = (s) => new ICSharpCode.SharpZipLib.BZip2.BZip2InputStream(s);
DecompressWithInflaterStream(createInflaterStream, encoding, buffer);
break;
case "gzip":
createInflaterStream = (s) => new ICSharpCode.SharpZipLib.GZip.GZipInputStream(s);
DecompressWithInflaterStream(createInflaterStream, encoding, buffer);
break;
case "lzw":
createInflaterStream = (s) => new ICSharpCode.SharpZipLib.Lzw.LzwInputStream(s);
DecompressWithInflaterStream(createInflaterStream, encoding, buffer);
break;
default:
throw new NotImplementedException();
}
}
protected void DecompressWithInflaterStream(Func<Stream, Stream> createDeflaterStream, Encoding encoding, byte[] buffer)
{
_content = _content ?? new string[_contentIds.Length];
using (var inStream = new MemoryStream(_compressedContent))
{
using (var outStream = createDeflaterStream(inStream))
{
var offsets = new uint[_contentIds.Length];
for (int i = 0; i < _contentIds.Length; ++i)
{
outStream.Read(buffer, 0, 4);
offsets[i] = BigEndianBitConverter.ToUInt32(buffer, 0);
}
long position = 4 * _contentIds.Length;
long positionAfterTable = position;
for (int i = 0; i < _contentIds.Length; ++i)
{
var toSkip = position - (offsets[i] + positionAfterTable);
if (0 != toSkip)
{
Skip(outStream, toSkip, buffer);
}
else if (toSkip < 0)
{
throw new InvalidOperationException("Can not go backwards");
}
try
{
_content[i] = BigEndianBitConverter.ReadBigText(outStream, encoding, buffer, ref position);
}
catch (Exception e)
{
System.Diagnostics.Debugger.Launch();
_content[i] = "Content is not available because lzma2 decompression reached end before position were content was supposed to be";
}
}
}
}
}
void Skip(Stream stream, long count, byte[] buffer)
{
var l = buffer.Length;
while (count > 0)
{
var rd = stream.Read(buffer, 0, (int)Math.Min(l, count));
count -= rd;
}
}
}
}
|