Added CRC32 and file size checks, #2.

LICENSE.txt

@@ -1,4 +1,4 @@
-Copyright (c) 2012 Alexey Yakovlev
+Copyright (c) 2012-2013 Alexey Yakovlev
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

Nuget/Unzip.nuspec

@@ -2,15 +2,15 @@
 <package >
   <metadata>
     <id>Unzip</id>
-    <version>0.3</version>
+    <version>0.4</version>
     <authors>yallie</authors>
     <owners>yallie</owners>
     <licenseUrl>https://github.com/yallie/unzip/raw/master/LICENSE.txt</licenseUrl>
     <projectUrl>https://github.com/yallie/unzip</projectUrl>
     <requireLicenseAcceptance>false</requireLicenseAcceptance>
     <description>Tiny unzip helper class for .NET 3.5 Client Profile and Mono 2.10. This package is source-code only, it copies single Unzip.cs file to the Internals folder of your project.</description>
-    <releaseNotes>Fixed extraction of empty directories (contributed by pysco68).</releaseNotes>
-    <copyright>Copyright 2012 Alexey Yakovlev</copyright>
+    <releaseNotes>Added CRC32 and file size checks (suggested by Per Lundberg).</releaseNotes>
+    <copyright>Copyright 2012-2013 Alexey Yakovlev</copyright>
     <tags>unzip decompression zip archive C# source</tags>
   </metadata>
 </package>

README.md

@@ -47,3 +47,10 @@ Full-featured libraries
 * [SharpZipLib](http://www.icsharpcode.net/opensource/sharpziplib/) supports Zip, GZip, Tar and BZip2 archives. GPL. ~200k.
 * [DotNetZip](http://dotnetzip.codeplex.com/) supports Silverlight and Compact framework, AES encryption. MS-PL. ~250-480k.
 * [SharpCompress](http://sharpcompress.codeplex.com/) supports Zip, Gzip, Tar, Rar and 7z. MS-PL. ~440K.
+
+Thanks
+------
+
+* Yannic Staudt @pysco68 for contributing a bugfix
+* Per Lundberg @perlun for feature requests
+* Damien Guard @damieng for CRC32 computation algorithm

Unzip.cs

@@ -82,6 +82,42 @@ public class Entry
 			public int DataOffset { get; set; }
 		}
 
+		private static readonly uint[] Crc32Table =
+		{
+			0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
+			0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
+			0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
+			0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
+			0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
+			0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
+			0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
+			0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
+			0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
+			0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
+			0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
+			0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
+			0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
+			0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
+			0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+			0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
+			0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
+			0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
+			0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
+			0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
+			0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
+			0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
+			0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
+			0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
+			0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
+			0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
+			0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
+			0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
+			0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
+			0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+			0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
+			0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d,
+		};
+
 		/// <summary>
 		/// Initializes a new instance of the <see cref="Unzip" /> class.
 		/// </summary>
@@ -159,6 +195,14 @@ public void Extract(string fileName, string outputFileName)
 				Extract(entry, outStream);
 			}
 
+			var fileInfo = new FileInfo(outputFileName);
+			if (fileInfo.Length != entry.OriginalSize)
+			{
+				throw new InvalidDataException(string.Format(
+					"Corrupted archive: {0} has an uncompressed size {1} which does not match its expected size {2}",
+					outputFileName, fileInfo.Length, entry.OriginalSize));
+			}
+
 			File.SetLastWriteTime(outputFileName, entry.Timestamp);
 		}
 
@@ -197,7 +241,7 @@ public void Extract(Entry entry, Stream outputStream)
 			Stream.Seek(entry.HeaderOffset, SeekOrigin.Begin);
 			if (Reader.ReadInt32() != FileSignature)
 			{
-				throw new InvalidOperationException("File signature doesn't match.");
+				throw new InvalidDataException("File signature doesn't match.");
 			}
 
 			// move to file data
@@ -208,10 +252,11 @@ public void Extract(Entry entry, Stream outputStream)
 				inputStream = new DeflateStream(Stream, CompressionMode.Decompress, true);
 			}
 
-			// allocate buffer
+			// allocate buffer, prepare for CRC32 calculation
 			var count = entry.OriginalSize;
 			var bufferSize = Math.Min(BufferSize, entry.OriginalSize);
 			var buffer = new byte[bufferSize];
+			var crc = 0xffffffff;
 
 			while (count > 0)
 			{
@@ -222,10 +267,28 @@ public void Extract(Entry entry, Stream outputStream)
 					break;
 				}
 
+				// compute CRC32
+				for (var i = 0; i < read; i++)
+				{
+					unchecked
+					{
+						crc = (crc >> 8) ^ Crc32Table[buffer[i] ^ crc & 0xff];
+					}
+				}
+
 				// copy to the output stream
 				outputStream.Write(buffer, 0, read);
 				count -= read;
 			}
+
+			// finalize CRC32 calculation
+			crc ^= 0xffffffff;
+			if ((int)crc != entry.Crc32)
+			{
+				throw new InvalidDataException(string.Format(
+					"Corrupted archive: CRC32 doesn't match on file {0}: expected {1:x8}, got {2:x8}.",
+					entry.Name, entry.Crc32, crc));
+			}
 		}
 
 		/// <summary>