private Stream OpenInReadMode(bool checkOpenable) { if (checkOpenable) { ThrowIfNotOpenable(needToUncompress: true, needToLoadIntoMemory: false); } Stream compressedStream = null; if (_archive.ArchiveStream is MemoryStream ms) { var buffer = ms.GetBuffer(); var readOnlySequence = new ReadOnlySequence <byte>(buffer, (int)OffsetOfCompressedData, (int)_compressedSize); compressedStream = new ReadOnlySequenceStream(readOnlySequence); } else { //old implementation, not thread safe in readmode compressedStream = new SubReadStream(_archive.ArchiveStream, OffsetOfCompressedData, _compressedSize); } //_archive.AddActiveReference(); return(GetDataDecompressor(compressedStream)); }
public static List <ZipGenericExtraField> GetExtraFields(BinaryReader reader) { // assumes that TrySkipBlock has already been called, so we don't have to validate twice List <ZipGenericExtraField> result; const int OffsetToFilenameLength = 26; // from the point before the signature reader.BaseStream.Seek(OffsetToFilenameLength, SeekOrigin.Current); ushort filenameLength = reader.ReadUInt16(); ushort extraFieldLength = reader.ReadUInt16(); reader.BaseStream.Seek(filenameLength, SeekOrigin.Current); using (Stream str = new SubReadStream(reader.BaseStream, reader.BaseStream.Position, extraFieldLength)) { result = ZipGenericExtraField.ParseExtraField(str); } Zip64ExtraField.RemoveZip64Blocks(result); return(result); }
// if saveExtraFieldsAndComments is false, FileComment and ExtraFields will be null // in either case, the zip64 extra field info will be incorporated into other fields public static bool TryReadBlock(BinaryReader reader, bool saveExtraFieldsAndComments, out ZipCentralDirectoryFileHeader header) { header = new ZipCentralDirectoryFileHeader(); if (reader.ReadUInt32() != SignatureConstant) { return(false); } header.VersionMadeBySpecification = reader.ReadByte(); header.VersionMadeByCompatibility = reader.ReadByte(); header.VersionNeededToExtract = reader.ReadUInt16(); header.GeneralPurposeBitFlag = reader.ReadUInt16(); header.CompressionMethod = reader.ReadUInt16(); header.LastModified = reader.ReadUInt32(); header.Crc32 = reader.ReadUInt32(); uint compressedSizeSmall = reader.ReadUInt32(); uint uncompressedSizeSmall = reader.ReadUInt32(); header.FilenameLength = reader.ReadUInt16(); header.ExtraFieldLength = reader.ReadUInt16(); header.FileCommentLength = reader.ReadUInt16(); ushort diskNumberStartSmall = reader.ReadUInt16(); header.InternalFileAttributes = reader.ReadUInt16(); header.ExternalFileAttributes = reader.ReadUInt32(); uint relativeOffsetOfLocalHeaderSmall = reader.ReadUInt32(); header.Filename = reader.ReadBytes(header.FilenameLength); bool uncompressedSizeInZip64 = uncompressedSizeSmall == ZipHelper.Mask32Bit; bool compressedSizeInZip64 = compressedSizeSmall == ZipHelper.Mask32Bit; bool relativeOffsetInZip64 = relativeOffsetOfLocalHeaderSmall == ZipHelper.Mask32Bit; bool diskNumberStartInZip64 = diskNumberStartSmall == ZipHelper.Mask16Bit; Zip64ExtraField zip64; long endExtraFields = reader.BaseStream.Position + header.ExtraFieldLength; using (Stream str = new SubReadStream(reader.BaseStream, reader.BaseStream.Position, header.ExtraFieldLength)) { if (saveExtraFieldsAndComments) { header.ExtraFields = ZipGenericExtraField.ParseExtraField(str); zip64 = Zip64ExtraField.GetAndRemoveZip64Block(header.ExtraFields, uncompressedSizeInZip64, compressedSizeInZip64, relativeOffsetInZip64, diskNumberStartInZip64); } else { header.ExtraFields = null; zip64 = Zip64ExtraField.GetJustZip64Block(str, uncompressedSizeInZip64, compressedSizeInZip64, relativeOffsetInZip64, diskNumberStartInZip64); } } // There are zip files that have malformed ExtraField blocks in which GetJustZip64Block() silently bails out without reading all the way to the end // of the ExtraField block. Thus we must force the stream's position to the proper place. reader.BaseStream.AdvanceToPosition(endExtraFields); if (saveExtraFieldsAndComments) { header.FileComment = reader.ReadBytes(header.FileCommentLength); } else { reader.BaseStream.Position += header.FileCommentLength; header.FileComment = null; } header.UncompressedSize = zip64.UncompressedSize == null ? uncompressedSizeSmall : zip64.UncompressedSize.Value; header.CompressedSize = zip64.CompressedSize == null ? compressedSizeSmall : zip64.CompressedSize.Value; header.RelativeOffsetOfLocalHeader = zip64.LocalHeaderOffset == null ? relativeOffsetOfLocalHeaderSmall : zip64.LocalHeaderOffset.Value; header.DiskNumberStart = zip64.StartDiskNumber == null ? diskNumberStartSmall : zip64.StartDiskNumber.Value; return(true); }