Merge pull request #3921 from shrah/null_check

Add null check for inline string marshalling

src/Common/src/TypeSystem/Interop/IL/Marshaller.cs

@@ -1902,11 +1902,18 @@ namespace Internal.TypeSystem.Interop
                 codeStream.EmitLdArg(0);
                 codeStream.Emit(ILOpcode.ldfld, emitter.NewToken(_managedField));
 
+                var lNullCheck = emitter.NewCodeLabel();
+                codeStream.Emit(ILOpcode.brfalse, lNullCheck);
+
+                codeStream.EmitLdArg(0);
+                codeStream.Emit(ILOpcode.ldfld, emitter.NewToken(_managedField));
+
                 codeStream.Emit(ILOpcode.ldlen);
                 codeStream.Emit(ILOpcode.conv_i4);
                 codeStream.EmitStLoc(vLength);
 
-                
+                codeStream.EmitLabel(lNullCheck);
+
                 Debug.Assert(MarshalAsDescriptor.SizeConst.HasValue);
                 int sizeConst = (int)MarshalAsDescriptor.SizeConst.Value;
 
@@ -1969,8 +1976,6 @@ namespace Internal.TypeSystem.Interop
             // check if ManagedType == null, then return
             codeStream.EmitLdArg(0);
             codeStream.Emit(ILOpcode.ldfld, emitter.NewToken(_managedField));
-            codeStream.Emit(ILOpcode.ldnull);
-            codeStream.Emit(ILOpcode.cgt_un);
             codeStream.Emit(ILOpcode.brfalse, lDone);
 
             codeStream.EmitLdArg(1);

src/System.Private.CoreLib/src/Internal/Runtime/CompilerHelpers/InteropHelpers.cs

@@ -42,6 +42,12 @@ namespace Internal.Runtime.CompilerHelpers
             if (buffer == null)
                 return;
 
+            if (str == null)
+            {
+                buffer[0] = '\0';
+                return;
+            }
+
             Debug.Assert(str.Length >= length);
 
             fixed (char* pStr = str)

tests/src/Simple/PInvoke/PInvoke.cs

@@ -187,6 +187,18 @@ namespace PInvokeTests
         [DllImport("*", CallingConvention = CallingConvention.StdCall)]
         internal static extern IntPtr GetFunctionPointer();
 
+
+        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
+        internal unsafe struct InlineString
+        {
+            internal uint size;
+            [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
+            internal string name;
+        }
+
+        [DllImport("*", CallingConvention = CallingConvention.StdCall)]
+        static extern bool InlineStringTest(ref InlineString ias);
+
         public static int Main(string[] args)
         {
             TestBlittableType();
@@ -591,6 +603,10 @@ namespace PInvokeTests
             }
             ThrowIfNotEquals(true, StructTest_Array(ssa, ssa.Length), "Array of struct marshalling failed");
 
+            InlineString ils = new InlineString();
+            InlineStringTest(ref ils);
+            ThrowIfNotEquals("Hello World!", ils.name, "Inline string marshalling failed");
+
             InlineArrayStruct ias = new InlineArrayStruct();
             ias.inlineArray = new short[128];
 

tests/src/Simple/PInvoke/PInvokeNative.cpp

@@ -628,6 +628,18 @@ DLL_EXPORT void* __stdcall GetFunctionPointer()
 {
     return (void*)&SetLastErrorFunc;
 }
+
+typedef struct {
+    int c;
+    char inlineString[260];
+} inlineString;
+
+DLL_EXPORT  bool __stdcall InlineStringTest(inlineString* p)
+{
+    CopyAnsiString(p->inlineString, "Hello World!");
+    return true;
+}
+
 #if (_MSC_VER >= 1400)         // Check MSC version
 #pragma warning(pop)           // Renable previous depreciations
 #endif