Merge pull request dotnet/coreclr#14085 from qmfrederik/marshal-utf8-…

…intptr-zero Fix marshaling IntPtr.Zero to UTF8 strings, add unit tests Commit migrated from dotnet/coreclr@4c979bd
godspeedu · Sep 20, 2017 · 4f4ca65 · 4f4ca65
2 parents 18d33a4 + 9a59c52
commit 4f4ca65
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Showing 2 changed files with 28 additions and 2 deletions.
diff --git a/src/coreclr/src/mscorlib/src/System/Runtime/InteropServices/Marshal.cs b/src/coreclr/src/mscorlib/src/System/Runtime/InteropServices/Marshal.cs
@@ -187,8 +187,15 @@ public static String PtrToStringAuto(IntPtr ptr)
 
         unsafe public static String PtrToStringUTF8(IntPtr ptr)
         {
-            int nbBytes = System.StubHelpers.StubHelpers.strlen((sbyte*)ptr.ToPointer());
-            return PtrToStringUTF8(ptr, nbBytes);
+            if (IntPtr.Zero == ptr)
+            {
+                return null;
+            }
+            else
+            {
+                int nbBytes = System.StubHelpers.StubHelpers.strlen((sbyte*)ptr.ToPointer());
+                return PtrToStringUTF8(ptr, nbBytes);
+            }
         }
 
         unsafe public static String PtrToStringUTF8(IntPtr ptr, int byteLen)

diff --git a/src/coreclr/tests/src/Interop/MarshalAPI/String/StringMarshalingTest.cs b/src/coreclr/tests/src/Interop/MarshalAPI/String/StringMarshalingTest.cs
@@ -231,6 +231,24 @@ public  void TestUTF8String()
         }
     }
 
+    private void TestNullString()
+    {
+        if (Marshal.PtrToStringUTF8(IntPtr.Zero) != null)
+        {
+            throw new Exception("IntPtr.Zero not marshaled to null for UTF8 strings");
+        }
+
+        if (Marshal.PtrToStringUni(IntPtr.Zero) != null)
+        {
+            throw new Exception("IntPtr.Zero not marshaled to null for Unicode strings");
+        }
+
+        if (Marshal.PtrToStringAnsi(IntPtr.Zero) != null)
+        {
+            throw new Exception("IntPtr.Zero not marshaled to null for ANSI strings");
+        }
+    }
+
     public  bool RunTests()
     {
         StringToBStrToString();
@@ -240,6 +258,7 @@ public  bool RunTests()
         StringToHGlobalAnsiToString();
         StringToHGlobalUniToString();
         TestUTF8String();
+        TestNullString();
         return true;
     }