/// <summary> /// Process extra data fields updating the entry based on the contents. /// </summary> /// <param name="localHeader">True if the extra data fields should be handled /// for a local header, rather than for a central header. /// </param> 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); } }