add Image.IsAssembly method and associated tests

Mono.Reflection.csproj

@@ -46,6 +46,7 @@
     <Compile Include="Mono.Reflection\BackingFieldResolver.cs" />
     <Compile Include="Mono.Reflection\Disassembler.cs" />
     <Compile Include="Mono.Reflection\ILPattern.cs" />
+    <Compile Include="Mono.Reflection\Image.cs" />
     <Compile Include="Mono.Reflection\MethodBodyReader.cs" />
     <Compile Include="Mono.Reflection\Instruction.cs" />
   </ItemGroup>

Mono.Reflection/Image.cs

@@ -0,0 +1,115 @@
+//
+// Image.cs
+//
+// Author:
+//   Jb Evain (jbevain@novell.com)
+//
+// (C) 2009 - 2010 Novell, Inc. (http://www.novell.com)
+//
+// Permission is hereby granted, free of charge, to any person obtaining
+// a copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to
+// permit persons to whom the Software is furnished to do so, subject to
+// the following conditions:
+//
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+//
+
+using System;
+using System.IO;
+
+namespace Mono.Reflection {
+
+	public class Image : IDisposable {
+
+		long position;
+		Stream stream;
+
+		Image (Stream stream)
+		{
+			this.stream = stream;
+			this.position = stream.Position;
+			this.stream.Position = 0;
+		}
+
+		bool Advance (int length)
+		{
+			if (stream.Position + length >= stream.Length)
+				return false;
+
+			stream.Seek (length, SeekOrigin.Current);
+			return true;
+		}
+
+		bool MoveTo (uint position)
+		{
+			if (position >= stream.Length)
+				return false;
+
+			stream.Position = position;
+			return true;
+		}
+
+		void IDisposable.Dispose ()
+		{
+			stream.Position = position;
+		}
+
+		ushort ReadUInt16 ()
+		{
+			return (ushort) (stream.ReadByte ()
+				| (stream.ReadByte () << 8));
+		}
+
+		uint ReadUInt32 ()
+		{
+			return (uint) (stream.ReadByte ()
+				| (stream.ReadByte () << 8)
+				| (stream.ReadByte () << 16)
+				| (stream.ReadByte () << 24));
+		}
+
+		bool IsManagedAssembly ()
+		{
+			if (stream.Length < 318)
+				return false;
+			if (ReadUInt16 () != 0x5a4d)
+				return false;
+			if (!Advance (58))
+				return false;
+			if (!MoveTo (ReadUInt32 ()))
+				return false;
+			if (ReadUInt32 () != 0x00004550)
+				return false;
+			if (!Advance (20))
+				return false;
+			if (!Advance (ReadUInt16 () == 0x20b ? 222 : 206))
+				return false;
+
+			return ReadUInt32 () != 0;
+		}
+
+		public static bool IsAssembly (string file)
+		{
+			using (var stream = new FileStream (file, FileMode.Open, FileAccess.Read, FileShare.Read))
+				return IsAssembly (stream);
+		}
+
+		public static bool IsAssembly (Stream stream)
+		{
+			using (var image = new Image (stream))
+				return image.IsManagedAssembly ();
+		}
+	}
+}

Test/Mono.Reflection.Tests.csproj

@@ -43,6 +43,7 @@
     <Compile Include="Mono.Reflection\AssemblyInfo.cs" />
     <Compile Include="Mono.Reflection\BackingFieldResolverTest.cs" />
     <Compile Include="Mono.Reflection\BaseReflectionTest.cs" />
+    <Compile Include="Mono.Reflection\ImageTest.cs" />
     <Compile Include="Mono.Reflection\DisassemblerTest.cs" />
     <Compile Include="Mono.Reflection\Formatter.cs" />
   </ItemGroup>

Test/Mono.Reflection/ImageTest.cs

@@ -0,0 +1,51 @@
+//
+// ImageTest.cs
+//
+// Author:
+//   Jb Evain (jbevain@novell.com)
+//
+// (C) 2009 - 2010 Novell, Inc. (http://www.novell.com)
+//
+// Permission is hereby granted, free of charge, to any person obtaining
+// a copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to
+// permit persons to whom the Software is furnished to do so, subject to
+// the following conditions:
+//
+// The above copyright notice and this permission notice shall be
+// included in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+//
+
+using System;
+using System.IO;
+
+using NUnit.Framework;
+
+namespace Mono.Reflection {
+
+	[TestFixture]
+	public class ImageTest : BaseReflectionTest {
+
+		[Test]
+		public void Assembly ()
+		{
+			Assert.IsTrue (Image.IsAssembly ("Mono.Reflection.dll"));
+		}
+
+		[Test]
+		public void NotAssembly ()
+		{
+			Assert.IsFalse (Image.IsAssembly ("Mono.Reflection.pdb"));
+		}
+	}
+}