internal SevenZipStreamsExtractor(Stream stream, SevenZipHeader.StreamsInfo streamsInfo, string password = null)
{
this.password = password;
this.stream = stream;
this.streamsInfo = streamsInfo;
}
private void writeHeaders()
{
// current position is defined as end of packed streams and beginning of header
long endOfPackedStreamsPosition = stream.Position;
// write headers in temporary stream
var headerStream = new MemoryStream();
header.Write(headerStream);
// go through compressing again for headers
if (CompressHeader)
{
// get compressor and default codec
var sc = new SevenZipStreamsCompressor(stream);
sc.Method = Compression.Registry.Method.LZMA;
// compress
headerStream.Position = 0;
SevenZipStreamsCompressor.PackedStream cs = sc.Compress(headerStream, null);
// create encoded header
SevenZipHeader.StreamsInfo headerStreamsInfo = new SevenZipHeader.StreamsInfo()
{
PackInfo = new SevenZipHeader.PackInfo()
{
NumPackStreams = cs.NumStreams,
PackPos = (ulong)(endOfPackedStreamsPosition - Marshal.SizeOf(typeof(SevenZipArchive.SignatureHeader))),
Sizes = cs.Sizes,
Digests = new SevenZipHeader.Digests(1)
{
CRCs = cs.CRCs
}
},
UnPackInfo = new SevenZipHeader.UnPackInfo()
{
Folders = new SevenZipHeader.Folder[1] {
cs.Folder
},
NumFolders = 1
}
};
// bait and switch
header.RawHeader = null;
header.EncodedHeader = headerStreamsInfo;
// write new header in headerStream
headerStream.Dispose();
headerStream = new MemoryStream();
header.Write(headerStream);
// update new end of packed position for encoded header
endOfPackedStreamsPosition = stream.Position;
}
// create start header and calculate header crc
headerStream.Position = 0;
var startHeader = new SevenZipArchive.StartHeader()
{
NextHeaderOffset = (ulong)(endOfPackedStreamsPosition - Marshal.SizeOf(typeof(SevenZipArchive.SignatureHeader))),
NextHeaderSize = (ulong)headerStream.Length,
NextHeaderCRC = CRC.Calculate(headerStream)
};
// write headers at the end of output stream
headerStream.Position = 0;
headerStream.CopyTo(stream);
headerStream.Dispose();
// regenerate signature header with positions and crcs
var signatureHeader = new SevenZipArchive.SignatureHeader()
{
Signature = SevenZipArchive.kSignature.ToArray(),
ArchiveVersion = new SevenZipArchive.ArchiveVersion()
{
Major = 0,
Minor = 2,
},
StartHeaderCRC = CRC.Calculate(startHeader.GetByteArray()),
StartHeader = startHeader
};
// write start header and flush all pending writes
stream.Position = 0;
stream.Write(signatureHeader.GetByteArray(), 0, Marshal.SizeOf(signatureHeader));
stream.Flush();
}