Calculates a 32bit Cyclic Redundancy Checksum (CRC) using the same polynomial used by Zip.
示例#1
0
        private void WriteHeader(System.IO.Stream s, byte[] bytes)
        {
            // write the header info

            int i = 0;
            // signature
            bytes[i++] = (byte)(ZipEntrySignature & 0x000000FF);
            bytes[i++] = (byte)((ZipEntrySignature & 0x0000FF00) >> 8);
            bytes[i++] = (byte)((ZipEntrySignature & 0x00FF0000) >> 16);
            bytes[i++] = (byte)((ZipEntrySignature & 0xFF000000) >> 24);

            // version needed
            Int16 FixedVersionNeeded = 0x14; // from examining existing zip files
            bytes[i++] = (byte)(FixedVersionNeeded & 0x00FF);
            bytes[i++] = (byte)((FixedVersionNeeded & 0xFF00) >> 8);

            // bitfield
            Int16 BitField = 0x00; // from examining existing zip files
            bytes[i++] = (byte)(BitField & 0x00FF);
            bytes[i++] = (byte)((BitField & 0xFF00) >> 8);

            // compression method
            Int16 CompressionMethod = 0x08; // 0x08 = Deflate
            bytes[i++] = (byte)(CompressionMethod & 0x00FF);
            bytes[i++] = (byte)((CompressionMethod & 0xFF00) >> 8);

            // LastMod
            bytes[i++] = (byte)(_LastModDateTime & 0x000000FF);
            bytes[i++] = (byte)((_LastModDateTime & 0x0000FF00) >> 8);
            bytes[i++] = (byte)((_LastModDateTime & 0x00FF0000) >> 16);
            bytes[i++] = (byte)((_LastModDateTime & 0xFF000000) >> 24);

            // CRC32 (Int32)
            CRC32 crc32 = new CRC32();
            UInt32 crc = 0;
            using (System.IO.Stream input = System.IO.File.OpenRead(FileName))
            {
                crc = crc32.GetCrc32AndCopy(input, CompressedStream);
            }
            CompressedStream.Close();  // to get the footer bytes written to the underlying stream

            bytes[i++] = (byte)(crc & 0x000000FF);
            bytes[i++] = (byte)((crc & 0x0000FF00) >> 8);
            bytes[i++] = (byte)((crc & 0x00FF0000) >> 16);
            bytes[i++] = (byte)((crc & 0xFF000000) >> 24);

            // CompressedSize (Int32)
            Int32 isz = (Int32)_UnderlyingMemoryStream.Length;
            UInt32 sz = (UInt32)isz;
            bytes[i++] = (byte)(sz & 0x000000FF);
            bytes[i++] = (byte)((sz & 0x0000FF00) >> 8);
            bytes[i++] = (byte)((sz & 0x00FF0000) >> 16);
            bytes[i++] = (byte)((sz & 0xFF000000) >> 24);

            // UncompressedSize (Int32)
            if (_Debug) System.Console.WriteLine("Uncompressed Size: {0}", crc32.TotalBytesRead);
            bytes[i++] = (byte)(crc32.TotalBytesRead & 0x000000FF);
            bytes[i++] = (byte)((crc32.TotalBytesRead & 0x0000FF00) >> 8);
            bytes[i++] = (byte)((crc32.TotalBytesRead & 0x00FF0000) >> 16);
            bytes[i++] = (byte)((crc32.TotalBytesRead & 0xFF000000) >> 24);

            string internalFileName = IncludeDirectoryTree ? FileName : Path.GetFileName(FileName);

            // filename length (Int16)
            Int16 length = (Int16)internalFileName.Length;
            // see note below about TrimVolumeFromFullyQualifiedPaths.
            if ((TrimVolumeFromFullyQualifiedPaths) && (internalFileName[1] == ':') && (internalFileName[2] == '\\')) length -= 3;
            bytes[i++] = (byte)(length & 0x00FF);
            bytes[i++] = (byte)((length & 0xFF00) >> 8);

            // extra field length (short)
            Int16 ExtraFieldLength = 0x00;
            bytes[i++] = (byte)(ExtraFieldLength & 0x00FF);
            bytes[i++] = (byte)((ExtraFieldLength & 0xFF00) >> 8);

            // Tue, 27 Mar 2007  16:35

            // Creating a zip that contains entries with "fully qualified" pathnames
            // can result in a zip archive that is unreadable by Windows Explorer.
            // Such archives are valid according to other tools but not to explorer.
            // To avoid this, we can trim off the leading volume name and slash (eg
            // c:\) when creating (writing) a zip file.  We do this by default and we
            // leave the old behavior available with the
            // TrimVolumeFromFullyQualifiedPaths flag - set it to false to get the old
            // behavior.  It only affects zip creation.

            // actual filename
            char[] c = ((TrimVolumeFromFullyQualifiedPaths) && (internalFileName[1] == ':') && (internalFileName[2] == '\\')) ?
              internalFileName.Substring(3).ToCharArray() :  // trim off volume letter, colon, and slash
              internalFileName.ToCharArray();

            int j = 0;

            if (_Debug)
            {
                System.Console.WriteLine("local header: writing filename, {0} chars", c.Length);
                System.Console.WriteLine("starting offset={0}", i);
            }
            for (j = 0; (j < c.Length) && (i + j < bytes.Length); j++)
            {
                bytes[i + j] = System.BitConverter.GetBytes(c[j])[0];
                if (_Debug) System.Console.Write(" {0:X2}", bytes[i + j]);
            }
            if (_Debug) System.Console.WriteLine();

            i += j;

            // extra field (we always write nothing in this implementation)
            // ;;

            // remember the file offset of this header
            _RelativeOffsetOfHeader = (int)s.Length;

            if (_Debug)
            {
                System.Console.WriteLine("\nAll header data:");
                for (j = 0; j < i; j++)
                    System.Console.Write(" {0:X2}", bytes[j]);
                System.Console.WriteLine();
            }
            // finally, write the header to the stream
            s.Write(bytes, 0, i);

            // preserve this header data for use with the central directory structure.
            _header = new byte[i];
            if (_Debug) System.Console.WriteLine("preserving header of {0} bytes", _header.Length);
            for (j = 0; j < i; j++)
                _header[j] = bytes[j];
        }
示例#2
0
        private void WriteHeader(System.IO.Stream s, byte[] bytes)
        {
            // write the header info

            int i = 0;

            // signature
            bytes[i++] = (byte)(ZipEntrySignature & 0x000000FF);
            bytes[i++] = (byte)((ZipEntrySignature & 0x0000FF00) >> 8);
            bytes[i++] = (byte)((ZipEntrySignature & 0x00FF0000) >> 16);
            bytes[i++] = (byte)((ZipEntrySignature & 0xFF000000) >> 24);

            // version needed
            Int16 FixedVersionNeeded = 0x14; // from examining existing zip files

            bytes[i++] = (byte)(FixedVersionNeeded & 0x00FF);
            bytes[i++] = (byte)((FixedVersionNeeded & 0xFF00) >> 8);

            // bitfield
            Int16 BitField = 0x00; // from examining existing zip files

            bytes[i++] = (byte)(BitField & 0x00FF);
            bytes[i++] = (byte)((BitField & 0xFF00) >> 8);

            // compression method
            Int16 CompressionMethod = 0x08; // 0x08 = Deflate

            bytes[i++] = (byte)(CompressionMethod & 0x00FF);
            bytes[i++] = (byte)((CompressionMethod & 0xFF00) >> 8);

            // LastMod
            bytes[i++] = (byte)(_LastModDateTime & 0x000000FF);
            bytes[i++] = (byte)((_LastModDateTime & 0x0000FF00) >> 8);
            bytes[i++] = (byte)((_LastModDateTime & 0x00FF0000) >> 16);
            bytes[i++] = (byte)((_LastModDateTime & 0xFF000000) >> 24);

            // CRC32 (Int32)
            CRC32  crc32 = new CRC32();
            UInt32 crc   = 0;

            using (System.IO.Stream input = System.IO.File.OpenRead(FileName))
            {
                crc = crc32.GetCrc32AndCopy(input, CompressedStream);
            }
            CompressedStream.Close();  // to get the footer bytes written to the underlying stream

            bytes[i++] = (byte)(crc & 0x000000FF);
            bytes[i++] = (byte)((crc & 0x0000FF00) >> 8);
            bytes[i++] = (byte)((crc & 0x00FF0000) >> 16);
            bytes[i++] = (byte)((crc & 0xFF000000) >> 24);

            // CompressedSize (Int32)
            Int32  isz = (Int32)_UnderlyingMemoryStream.Length;
            UInt32 sz  = (UInt32)isz;

            bytes[i++] = (byte)(sz & 0x000000FF);
            bytes[i++] = (byte)((sz & 0x0000FF00) >> 8);
            bytes[i++] = (byte)((sz & 0x00FF0000) >> 16);
            bytes[i++] = (byte)((sz & 0xFF000000) >> 24);

            // UncompressedSize (Int32)
            if (_Debug)
            {
                System.Console.WriteLine("Uncompressed Size: {0}", crc32.TotalBytesRead);
            }
            bytes[i++] = (byte)(crc32.TotalBytesRead & 0x000000FF);
            bytes[i++] = (byte)((crc32.TotalBytesRead & 0x0000FF00) >> 8);
            bytes[i++] = (byte)((crc32.TotalBytesRead & 0x00FF0000) >> 16);
            bytes[i++] = (byte)((crc32.TotalBytesRead & 0xFF000000) >> 24);

            string internalFileName = IncludeDirectoryTree ? FileName : Path.GetFileName(FileName);

            // filename length (Int16)
            Int16 length = (Int16)internalFileName.Length;

            // see note below about TrimVolumeFromFullyQualifiedPaths.
            if ((TrimVolumeFromFullyQualifiedPaths) && (internalFileName[1] == ':') && (internalFileName[2] == '\\'))
            {
                length -= 3;
            }
            bytes[i++] = (byte)(length & 0x00FF);
            bytes[i++] = (byte)((length & 0xFF00) >> 8);

            // extra field length (short)
            Int16 ExtraFieldLength = 0x00;

            bytes[i++] = (byte)(ExtraFieldLength & 0x00FF);
            bytes[i++] = (byte)((ExtraFieldLength & 0xFF00) >> 8);

            // Tue, 27 Mar 2007  16:35

            // Creating a zip that contains entries with "fully qualified" pathnames
            // can result in a zip archive that is unreadable by Windows Explorer.
            // Such archives are valid according to other tools but not to explorer.
            // To avoid this, we can trim off the leading volume name and slash (eg
            // c:\) when creating (writing) a zip file.  We do this by default and we
            // leave the old behavior available with the
            // TrimVolumeFromFullyQualifiedPaths flag - set it to false to get the old
            // behavior.  It only affects zip creation.

            // actual filename
            char[] c = ((TrimVolumeFromFullyQualifiedPaths) && (internalFileName[1] == ':') && (internalFileName[2] == '\\')) ?
                       internalFileName.Substring(3).ToCharArray() : // trim off volume letter, colon, and slash
                       internalFileName.ToCharArray();


            int j = 0;

            if (_Debug)
            {
                System.Console.WriteLine("local header: writing filename, {0} chars", c.Length);
                System.Console.WriteLine("starting offset={0}", i);
            }
            for (j = 0; (j < c.Length) && (i + j < bytes.Length); j++)
            {
                bytes[i + j] = System.BitConverter.GetBytes(c[j])[0];
                if (_Debug)
                {
                    System.Console.Write(" {0:X2}", bytes[i + j]);
                }
            }
            if (_Debug)
            {
                System.Console.WriteLine();
            }

            i += j;

            // extra field (we always write nothing in this implementation)
            // ;;

            // remember the file offset of this header
            _RelativeOffsetOfHeader = (int)s.Length;


            if (_Debug)
            {
                System.Console.WriteLine("\nAll header data:");
                for (j = 0; j < i; j++)
                {
                    System.Console.Write(" {0:X2}", bytes[j]);
                }
                System.Console.WriteLine();
            }
            // finally, write the header to the stream
            s.Write(bytes, 0, i);

            // preserve this header data for use with the central directory structure.
            _header = new byte[i];
            if (_Debug)
            {
                System.Console.WriteLine("preserving header of {0} bytes", _header.Length);
            }
            for (j = 0; j < i; j++)
            {
                _header[j] = bytes[j];
            }
        }