Add a test which changes the CompressionMethod of an item

CompressionMethod.cs

@@ -121,6 +121,26 @@ public enum CompressionMethod : short
 		/// </summary>
 		LZ77           = 19,
 
+		/// <summary>
+		/// LZMA2 Compressed data
+		/// </summary>
+		LZMA2          = 33,
+
+		/// <summary>
+		/// Zstandard compressed data
+		/// </summary>
+		ZSTD           = 93,
+
+		/// <summary>
+		/// XZ compressed data
+		/// </summary>
+		XZ             = 95,
+
+		/// <summary>
+		/// Compressed Jpeg data
+		/// </summary>
+		JPEG           = 96,
+
 		/// <summary>
 		/// WavPack compressed data
 		/// </summary>

LibZipSharp.UnitTest/LibZipSharp.UnitTest.csproj

@@ -29,6 +29,9 @@
       <Link>libzip.dll</Link>
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>
+    <None Include="packaged_resources">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
   </ItemGroup>
 
   <Target Name="RunNunitTests" DependsOnTargets="Build">

LibZipSharp.UnitTest/ZipTests.cs

@@ -192,6 +192,44 @@ public void SmallTextFile ()
 			}
 		}
 
+		[Test]
+		public void UpdateEntryCompressionMethod ()
+		{
+			var zipStream = new MemoryStream ();
+			var encoding = Encoding.UTF8;
+			using (var zip = ZipArchive.Create (zipStream)) {
+				zip.AddEntry ("foo", "bar", encoding, CompressionMethod.Deflate);
+			}
+			using (var zip = ZipArchive.Open (zipStream)) {
+				var entry = zip.ReadEntry ("foo");
+				Assert.IsNotNull (entry, "Entry 'foo' should exist!");
+				AssertEntryIsValid (entry, "foo", compression: CompressionMethod.Deflate);
+				using (var stream = new MemoryStream ()) {
+					entry.Extract (stream);
+					stream.Position = 0;
+					Assert.AreEqual ("bar", encoding.GetString (stream.ToArray ()));
+				}
+				zip.AddEntry ("foo", "foo", encoding, CompressionMethod.Store);
+				entry = zip.ReadEntry ("foo");
+				AssertEntryIsValid (entry, "foo", compression: CompressionMethod.Store);
+			}
+		}
+
+		[Test]
+		public void CheckForUnknownCompressionMethods ()
+		{
+			string filePath = Path.GetFullPath ("packaged_resources");
+			if (!File.Exists (filePath)) {
+					filePath = Path.GetFullPath (Path.Combine ("LibZipSharp.UnitTest", "packaged_resources"));
+			}
+			using (var zip = ZipArchive.Open (filePath, FileMode.Open)) {
+				foreach (var e in zip) {
+					Console.WriteLine ($"{e.FullName} is {e.CompressionMethod}");
+					Assert.AreNotEqual (CompressionMethod.Unknown, e.CompressionMethod, "Compression Method should not be Unknown.");
+				}
+			}
+		}
+
 		[TestCase (false)]
 		[TestCase (true)]
 		public void EnumerateSkipDeletedEntries (bool deleteFromExistingFile)

LibZipSharp.props

@@ -1,5 +1,5 @@
 <Project DefaultTargets="Build" ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
     <PropertyGroup>
-        <_LibZipSharpNugetVersion>1.0.21</_LibZipSharpNugetVersion>
+        <_LibZipSharpNugetVersion>1.0.22</_LibZipSharpNugetVersion>
     </PropertyGroup>
 </Project>

Native.cs

@@ -47,17 +47,28 @@ public struct zip_source_args_seek_t
 			public int whence;
 		};
 
+		[StructLayout(LayoutKind.Explicit)]
 		public struct zip_stat_t
 		{
+			[FieldOffset (0)]
 			public UInt64 valid;                 /* which fields have valid values */
+			[FieldOffset (8)]
 			public IntPtr name;                  /* name of the file (char *) */
+			[FieldOffset (16)]
 			public UInt64 index;                 /* index within archive */
+			[FieldOffset (24)]
 			public UInt64 size;                  /* size of file (uncompressed) */
+			[FieldOffset (32)]
 			public UInt64 comp_size;             /* size of file (compressed) */
+			[FieldOffset (40)]
 			public IntPtr mtime;                 /* modification time (time_t) */
+			[FieldOffset (48)]
 			public UInt32 crc;                   /* crc of file data */
+			[FieldOffset (52)]
 			public Int16  comp_method;           /* compression method used */
+			[FieldOffset (56)]
 			public UInt16 encryption_method;     /* encryption method used */
+			[FieldOffset (60)]
 			public UInt32 flags;                 /* reserved for future use */
 		};