/// <summary>
/// Computes a table that speeds up calculation of the CRC.
/// </summary>
private static uint[] MakeCrcTable()
{
const uint poly = 0x04C11DB7u;
uint[] crcTable = new uint[256];
for (uint n = 0; n < 256; n++)
{
uint c = CrcStream.Reflect(n, 8);
c = c << 24;
for (uint k = 0; k < 8; k++)
{
c = (c << 1) ^ ((c & 0x80000000u) != 0 ? poly : 0);
}
crcTable[n] = CrcStream.Reflect(c, 32);
}
return(crcTable);
}
/// <summary>
/// Writes compressed bytes of one file to the archive,
/// keeping track of the CRC and number of bytes written.
/// </summary>
private long PackFileBytes(
IPackStreamContext streamContext,
Stream fileStream,
long maxArchiveSize,
Converter <Stream, Stream> compressionStreamCreator,
ref Stream archiveStream,
out uint crc)
{
long writeStartPosition = archiveStream.Position;
long bytesWritten = 0;
CrcStream fileCrcStream = new CrcStream(fileStream);
ConcatStream concatStream = new ConcatStream(
delegate(ConcatStream s)
{
Stream sourceStream = s.Source;
bytesWritten += sourceStream.Position - writeStartPosition;
this.CheckArchiveWriteStream(
streamContext,
maxArchiveSize,
1,
ref sourceStream);
writeStartPosition = sourceStream.Position;
s.Source = sourceStream;
});
concatStream.Source = archiveStream;
if (maxArchiveSize > 0)
{
concatStream.SetLength(maxArchiveSize);
}
Stream compressionStream = compressionStreamCreator(concatStream);
try
{
byte[] buf = new byte[4096];
long bytesRemaining = fileStream.Length;
int counter = 0;
while (bytesRemaining > 0)
{
int count = (int)Math.Min(
bytesRemaining, (long)buf.Length);
count = fileCrcStream.Read(buf, 0, count);
if (count <= 0)
{
throw new ZipException(
"Failed to read file: " + this.currentFileName);
}
compressionStream.Write(buf, 0, count);
bytesRemaining -= count;
this.fileBytesProcessed += count;
this.currentFileBytesProcessed += count;
this.currentArchiveTotalBytes = concatStream.Source.Position;
this.currentArchiveBytesProcessed = this.currentArchiveTotalBytes;
if (++counter % 16 == 0) // Report every 64K
{
this.OnProgress(ArchiveProgressType.PartialFile);
}
}
if (compressionStream is DeflateStream)
{
compressionStream.Close();
}
else
{
compressionStream.Flush();
}
}
finally
{
archiveStream = concatStream.Source;
}
bytesWritten += archiveStream.Position - writeStartPosition;
crc = fileCrcStream.Crc;
return(bytesWritten);
}
/// <summary>
/// Decompresses bytes for one file from an archive or archive chain,
/// checking the crc at the end.
/// </summary>
private void UnpackFileBytes(
IUnpackStreamContext streamContext,
string fileName,
long compressedSize,
long uncompressedSize,
uint crc,
Stream fileStream,
Converter <Stream, Stream> compressionStreamCreator,
ref Stream archiveStream)
{
CrcStream crcStream = new CrcStream(fileStream);
ConcatStream concatStream = new ConcatStream(
delegate(ConcatStream s)
{
this.currentArchiveBytesProcessed = s.Source.Position;
streamContext.CloseArchiveReadStream(
this.currentArchiveNumber,
String.Empty,
s.Source);
this.currentArchiveNumber--;
this.OnProgress(ArchiveProgressType.FinishArchive);
this.currentArchiveNumber += 2;
this.currentArchiveName = null;
this.currentArchiveBytesProcessed = 0;
this.currentArchiveTotalBytes = 0;
s.Source = this.OpenArchive(streamContext, this.currentArchiveNumber);
FileStream archiveFileStream = s.Source as FileStream;
this.currentArchiveName = (archiveFileStream != null ?
Path.GetFileName(archiveFileStream.Name) : null);
this.currentArchiveTotalBytes = s.Source.Length;
this.currentArchiveNumber--;
this.OnProgress(ArchiveProgressType.StartArchive);
this.currentArchiveNumber++;
});
concatStream.Source = archiveStream;
concatStream.SetLength(compressedSize);
Stream decompressionStream = compressionStreamCreator(concatStream);
try
{
byte[] buf = new byte[4096];
long bytesRemaining = uncompressedSize;
int counter = 0;
while (bytesRemaining > 0)
{
int count = (int)Math.Min(buf.Length, bytesRemaining);
count = decompressionStream.Read(buf, 0, count);
crcStream.Write(buf, 0, count);
bytesRemaining -= count;
this.fileBytesProcessed += count;
this.currentFileBytesProcessed += count;
this.currentArchiveBytesProcessed = concatStream.Source.Position;
if (++counter % 16 == 0) // Report every 64K
{
this.currentArchiveNumber--;
this.OnProgress(ArchiveProgressType.PartialFile);
this.currentArchiveNumber++;
}
}
}
finally
{
archiveStream = concatStream.Source;
}
crcStream.Flush();
if (crcStream.Crc != crc)
{
throw new ZipException("CRC check failed for file: " + fileName);
}
}