ICSharpCode.SharpZipLib.Zip.ZipEntry.ProcessExtraData C# (CSharp) Méthode

        internal void ProcessExtraData(bool localHeader)
        {
            var extraData = new ZipExtraData(this.extra);

            if (extraData.Find(0x0001)) {
                // Version required to extract is ignored here as some archivers dont set it correctly
                // in theory it should be version 45 or higher

                // The recorded size will change but remember that this is zip64.
                forceZip64_ = true;

                if (extraData.ValueLength < 4) {
                    throw new ZipException("Extra data extended Zip64 information length is invalid");
                }

                // (localHeader ||) was deleted, because actually there is no specific difference with reading sizes between local header & central directory
                // https://pkware.cachefly.net/webdocs/casestudies/APPNOTE.TXT
                // ...
                // 4.4  Explanation of fields
                // ...
                //	4.4.8 compressed size: (4 bytes)
                //	4.4.9 uncompressed size: (4 bytes)
                //
                //		The size of the file compressed (4.4.8) and uncompressed,
                //		(4.4.9) respectively.  When a decryption header is present it
                //		will be placed in front of the file data and the value of the
                //		compressed file size will include the bytes of the decryption
                //		header.  If bit 3 of the general purpose bit flag is set,
                //		these fields are set to zero in the local header and the
                //		correct values are put in the data descriptor and
                //		in the central directory.  If an archive is in ZIP64 format
                //		and the value in this field is 0xFFFFFFFF, the size will be
                //		in the corresponding 8 byte ZIP64 extended information
                //		extra field.  When encrypting the central directory, if the
                //		local header is not in ZIP64 format and general purpose bit
                //		flag 13 is set indicating masking, the value stored for the
                //		uncompressed size in the Local Header will be zero.
                //
                // Othewise there is problem with minizip implementation
                if (size == uint.MaxValue) {
                    size = (ulong)extraData.ReadLong();
                }

                if (compressedSize == uint.MaxValue) {
                    compressedSize = (ulong)extraData.ReadLong();
                }

                if (!localHeader && (offset == uint.MaxValue)) {
                    offset = extraData.ReadLong();
                }

                // Disk number on which file starts is ignored
            } else {
                if (
                    ((versionToExtract & 0xff) >= ZipConstants.VersionZip64) &&
                    ((size == uint.MaxValue) || (compressedSize == uint.MaxValue))
                ) {
                    throw new ZipException("Zip64 Extended information required but is missing.");
                }
            }

            DateTime = GetDateTime(extraData);
            if (method == CompressionMethod.WinZipAES) {
                ProcessAESExtraData(extraData);
            }
        }

		/// <summary>
		/// Search for and read the central directory of a zip file filling the entries array.
		/// </summary>
		/// <exception cref="System.IO.IOException">
		/// An i/o error occurs.
		/// </exception>
		/// <exception cref="ICSharpCode.SharpZipLib.Zip.ZipException">
		/// The central directory is malformed or cannot be found
		/// </exception>
		void ReadEntries()
		{
			// Search for the End Of Central Directory.  When a zip comment is
			// present the directory will start earlier
			// 
			// The search is limited to 64K which is the maximum size of a trailing comment field to aid speed.
			// This should be compatible with both SFX and ZIP files but has only been tested for Zip files
			// If a SFX file has the Zip data attached as a resource and there are other resources occuring later then
			// this could be invalid.
			// Could also speed this up by reading memory in larger blocks.			

			if (baseStream_.CanSeek == false) {
				throw new ZipException("ZipFile stream must be seekable");
			}
			
			long locatedEndOfCentralDir = LocateBlockWithSignature(ZipConstants.EndOfCentralDirectorySignature,
				baseStream_.Length, ZipConstants.EndOfCentralRecordBaseSize, 0xffff);
			
			if (locatedEndOfCentralDir < 0) {
				throw new ZipException("Cannot find central directory");
			}

			// Read end of central directory record
			ushort thisDiskNumber           = ReadLEUshort();
			ushort startCentralDirDisk      = ReadLEUshort();
			ulong entriesForThisDisk        = ReadLEUshort();
			ulong entriesForWholeCentralDir = ReadLEUshort();
			ulong centralDirSize            = ReadLEUint();
			long offsetOfCentralDir         = ReadLEUint();
			uint commentSize                = ReadLEUshort();
			
			if ( commentSize > 0 ) {
				byte[] comment = new byte[commentSize]; 

				StreamUtils.ReadFully(baseStream_, comment);
				comment_ = ZipConstants.ConvertToString(comment); 
			}
			else {
				comment_ = string.Empty;
			}
			
			bool isZip64 = false;

			// Check if zip64 header information is required.
			if ( (thisDiskNumber == 0xffff) ||
				(startCentralDirDisk == 0xffff) ||
				(entriesForThisDisk == 0xffff) ||
				(entriesForWholeCentralDir == 0xffff) ||
				(centralDirSize == 0xffffffff) ||
				(offsetOfCentralDir == 0xffffffff) ) {
				isZip64 = true;

				long offset = LocateBlockWithSignature(ZipConstants.Zip64CentralDirLocatorSignature, locatedEndOfCentralDir, 0, 0x1000);
				if ( offset < 0 ) {
					throw new ZipException("Cannot find Zip64 locator");
				}

				// number of the disk with the start of the zip64 end of central directory 4 bytes 
				// relative offset of the zip64 end of central directory record 8 bytes 
				// total number of disks 4 bytes 
				ReadLEUint(); // startDisk64 is not currently used
				ulong offset64 = ReadLEUlong();
				uint totalDisks = ReadLEUint();

				baseStream_.Position = (long)offset64;
				long sig64 = ReadLEUint();

				if ( sig64 != ZipConstants.Zip64CentralFileHeaderSignature ) {
					throw new ZipException(string.Format("Invalid Zip64 Central directory signature at {0:X}", offset64));
				}

				// NOTE: Record size = SizeOfFixedFields + SizeOfVariableData - 12.
				ulong recordSize = ReadLEUlong();
				int versionMadeBy = ReadLEUshort();
				int versionToExtract = ReadLEUshort();
				uint thisDisk = ReadLEUint();
				uint centralDirDisk = ReadLEUint();
				entriesForThisDisk = ReadLEUlong();
				entriesForWholeCentralDir = ReadLEUlong();
				centralDirSize = ReadLEUlong();
				offsetOfCentralDir = (long)ReadLEUlong();

				// NOTE: zip64 extensible data sector (variable size) is ignored.
			}
			
			entries_ = new ZipEntry[entriesForThisDisk];
			
			// SFX/embedded support, find the offset of the first entry vis the start of the stream
			// This applies to Zip files that are appended to the end of an SFX stub.
			// Or are appended as a resource to an executable.
			// Zip files created by some archivers have the offsets altered to reflect the true offsets
			// and so dont require any adjustment here...
			// TODO: Difficulty with Zip64 and SFX offset handling needs resolution - maths?
			if ( !isZip64 && (offsetOfCentralDir < locatedEndOfCentralDir - (4 + (long)centralDirSize)) ) {
				offsetOfFirstEntry = locatedEndOfCentralDir - (4 + (long)centralDirSize + offsetOfCentralDir);
				if (offsetOfFirstEntry <= 0) {
					throw new ZipException("Invalid embedded zip archive");
				}
			}

			baseStream_.Seek(offsetOfFirstEntry + offsetOfCentralDir, SeekOrigin.Begin);
			
			for (ulong i = 0; i < entriesForThisDisk; i++) {
				if (ReadLEUint() != ZipConstants.CentralHeaderSignature) {
					throw new ZipException("Wrong Central Directory signature");
				}
				
				int versionMadeBy      = ReadLEUshort();
				int versionToExtract   = ReadLEUshort();
				int bitFlags           = ReadLEUshort();
				int method             = ReadLEUshort();
				uint dostime           = ReadLEUint();
				uint crc               = ReadLEUint();
				long csize             = (long)ReadLEUint();
				long size              = (long)ReadLEUint();
				int nameLen            = ReadLEUshort();
				int extraLen           = ReadLEUshort();
				int commentLen         = ReadLEUshort();
				
				int diskStartNo        = ReadLEUshort();  // Not currently used
				int internalAttributes = ReadLEUshort();  // Not currently used

				uint externalAttributes = ReadLEUint();
				long offset             = ReadLEUint();
				
				byte[] buffer = new byte[Math.Max(nameLen, commentLen)];
				
				StreamUtils.ReadFully(baseStream_, buffer, 0, nameLen);
				string name = ZipConstants.ConvertToStringExt(bitFlags, buffer, nameLen);
				
				ZipEntry entry = new ZipEntry(name, versionToExtract, versionMadeBy, (CompressionMethod)method);
				entry.Crc = crc & 0xffffffffL;
				entry.Size = size & 0xffffffffL;
				entry.CompressedSize = csize & 0xffffffffL;
				entry.Flags = bitFlags;
				entry.DosTime = (uint)dostime;
				entry.ZipFileIndex = (long)i;
				entry.Offset = offset;
				entry.ExternalFileAttributes = (int)externalAttributes;

				if ((bitFlags & 8) == 0) {
					entry.CryptoCheckValue = (byte)(crc >> 24);
				}
				else {
					entry.CryptoCheckValue = (byte)((dostime >> 8) & 0xff);
				}

				if (extraLen > 0) {
					byte[] extra = new byte[extraLen];
					StreamUtils.ReadFully(baseStream_, extra);
					entry.ExtraData = extra;
				}

				entry.ProcessExtraData(false);
				
				if (commentLen > 0) {
					StreamUtils.ReadFully(baseStream_, buffer, 0, commentLen);
					entry.Comment = ZipConstants.ConvertToStringExt(bitFlags, buffer, commentLen);
				}
				
				entries_[i] = entry;
			}
		}