[Mono-bugs] [Bug 71017][Nor] New - P/Invoke methods inside dynamic assemblies don't marshal strings properly

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Changed by jonpryor@vt.edu.

http://bugzilla.ximian.com/show_bug.cgi?id=71017

--- shadow/71017	2005-01-05 09:11:46.000000000 -0500
+++ shadow/71017.tmp.5245	2005-01-05 09:11:46.000000000 -0500
@@ -0,0 +1,118 @@
+Bug#: 71017
+Product: Mono: Runtime
+Version: unspecified
+OS: other
+OS Details: 
+Status: NEW   
+Resolution: 
+Severity: 
+Priority: Normal
+Component: misc
+AssignedTo: mono-bugs@ximian.com                            
+ReportedBy: jonpryor@vt.edu               
+QAContact: mono-bugs@ximian.com
+TargetMilestone: ---
+URL: 
+Cc: 
+Summary: P/Invoke methods inside dynamic assemblies don't marshal strings properly
+
+Please fill in this template when reporting a bug, unless you know what you
+are doing.
+Description of Problem:
+
+I'm not sure this is a runtime bug or a class library bug, and
+System.Reflection.Emit isn't a component of either, so flip a coin...
+
+If you use System.Reflection.Emit to create a dynamic assembly which
+contains a P/Invoke method with a string parameter, the string isn't
+marshaled correctly.  It isn't marshaled at all, actually -- the UTF-16
+string is passed as-is even when the P/Invoke method is declared as an Ansi
+function.
+
+This used to work on Mono 1.1.1, but now fails on svn-HEAD (revision 38347)
+
+Steps to reproduce the problem:
+1. Compile the following test program: mcs -g srem.cs:
+
+	// file: srem.cs
+	// System.Reflection.Emit P/Invoke Marshaling bug
+	// Works on Mono 1.1.1, fails on svn-HEAD
+	using System;
+	using System.Reflection;
+	using System.Reflection.Emit;
+	using System.Runtime.InteropServices;
+
+	class Test {
+		static MethodInfo CreateGetenv ()
+		{
+			AssemblyName an = new AssemblyName();
+			an.Name = "Support";
+			ModuleBuilder mb = AppDomain.CurrentDomain.DefineDynamicAssembly (an,
+				AssemblyBuilderAccess.Run).DefineDynamicModule (an.Name);
+			TypeBuilder tb = mb.DefineType ("SomeType", TypeAttributes.Public);
+			tb.DefinePInvokeMethod ("getenv", "libc",
+				MethodAttributes.PinvokeImpl | MethodAttributes.Static |
+					MethodAttributes.Public,
+				CallingConventions.Standard,
+				typeof(IntPtr),
+				new Type[]{typeof(string)},
+				CallingConvention.Cdecl,
+				CharSet.Ansi);
+			MethodInfo mi = tb.CreateType ().GetMethod ("getenv");
+			return mi;
+		}
+
+		[DllImport ("libc", CharSet=CharSet.Ansi, 
+			CallingConvention=CallingConvention.Cdecl)]
+		static extern IntPtr getenv (string name);
+
+		public static int Main (string[] args)
+		{
+			MethodInfo mi = CreateGetenv ();
+			foreach (string s in args) {
+				IntPtr _dynamic = (IntPtr) mi.Invoke (null, new object[]{s});
+				IntPtr _pinvoke = getenv (s);
+
+				string dynamic = Marshal.PtrToStringAnsi (_dynamic);
+				string pinvoke = Marshal.PtrToStringAnsi (_pinvoke);
+
+				Console.WriteLine ("Environment Variable: '{0}'", s);
+				Console.WriteLine ("\t     SRE Value: {0}", dynamic);
+				Console.WriteLine ("\tP/Invoke Value: {0}", pinvoke);
+			}
+			return 0;
+		}
+	}
+
+2. Run the program.  You must run this on Unix (it uses getenv(3)):
+
+	mono --debug srem.exe SHELL
+
+Actual Results:
+
+	Environment Variable: 'SHELL'
+	             SRE Value:
+	        P/Invoke Value: /bin/bash
+
+Expected Results:
+
+	Environment Variable: 'SHELL'
+	             SRE Value: /bin/bash
+	        P/Invoke Value: /bin/bash
+
+How often does this happen? 
+
+Always.
+
+Additional Information:
+
+Note that the value returned by invoking the
+System.Reflection.Emit-generated code is empty.  When running under gdb in
+a similar scenario with Mono.Posix, the string that was being passed to
+native code was a UTF-16 string, leading me to assume that when getenv is
+called by the SRE-generated code it's receiving:
+
+	{'S', '\0', 'H', '\0', 'E', '\0', 'L', '\0', 'L', '\0', '\0', '\0'}
+
+This is interpreted as "S", which isn't a valid environment variable, hence
+the null string that's returned.