csharp: Update string marshalers

Mostly done, needs work on strings being returned without ownership from
C# to C.

src/bin/eolian_mono/eolian/mono/marshall_annotation.hh

@@ -51,23 +51,22 @@ struct marshall_annotation_visitor_generate
         eina::optional<bool> has_own;
         std::function<std::string()> function;
       };
-      // These two tables are currently the same but will hold different marshallers
-      // for @in and @out/return semantics in a future commit.
-      match const parameter_match_table[] =
+
+      match const input_match_table[] =
         {
            // signed primitives
           {"bool", nullptr, [] { return "MarshalAs(UnmanagedType.U1)"; }},
           {"string", true, [] {
-                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringPassOwnershipMarshaler))";
+                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringInPassOwnershipMarshaler))";
           }},
           {"string", false, [] {
-                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringKeepOwnershipMarshaler))";
+                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringInKeepOwnershipMarshaler))";
           }},
           {"mstring", true, [] {
-                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringPassOwnershipMarshaler))";
+                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringInPassOwnershipMarshaler))";
           }},
           {"mstring", false, [] {
-                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringKeepOwnershipMarshaler))";
+                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringInKeepOwnershipMarshaler))";
           }},
           {"stringshare", true, [] {
                 return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringsharePassOwnershipMarshaler))";
@@ -96,16 +95,16 @@ struct marshall_annotation_visitor_generate
            // signed primitives
           {"bool", nullptr, [] { return "MarshalAs(UnmanagedType.U1)"; }},
           {"string", true, [] {
-                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringPassOwnershipMarshaler))";
+                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringOutPassOwnershipMarshaler))";
           }},
           {"string", false, [] {
-                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringKeepOwnershipMarshaler))";
+                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringOutKeepOwnershipMarshaler))";
           }},
           {"mstring", true, [] {
-                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringPassOwnershipMarshaler))";
+                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringOutPassOwnershipMarshaler))";
           }},
           {"mstring", false, [] {
-                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringKeepOwnershipMarshaler))";
+                return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringOutKeepOwnershipMarshaler))";
           }},
           {"stringshare", true, [] {
                 return "MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringsharePassOwnershipMarshaler))";
@@ -143,7 +142,7 @@ struct marshall_annotation_visitor_generate
             return as_generator("[" << prefix << marshalTag << "]").generate(sink, nullptr, *context);
           };
 
-        const auto& match_table = is_return ? return_match_table : parameter_match_table;
+        const auto& match_table = (is_return || is_out) ? return_match_table : input_match_table;
 
         if(eina::optional<bool> b = type_match::get_match(match_table, predicate, acceptCb))
           {

src/bindings/mono/eina_mono/eina_environment.cs

@@ -43,7 +43,7 @@ internal static class Environment
 internal static partial class NativeCustomExportFunctions
 {
     [DllImport(efl.Libs.CustomExports, CharSet=CharSet.Ansi)]
-    [return: MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringKeepOwnershipMarshaler))]
+    [return: MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef=typeof(Efl.Eo.StringOutKeepOwnershipMarshaler))]
     public static extern string efl_mono_native_getenv(string name);
 
     [DllImport(efl.Libs.CustomExports, CharSet=CharSet.Ansi)]

src/bindings/mono/eina_mono/eina_strbuf.cs

@@ -51,13 +51,13 @@ static internal class StrbufNativeMethods
     [DllImport(efl.Libs.Eina, CharSet=CharSet.Ansi)]
     [return:
      MarshalAs(UnmanagedType.CustomMarshaler,
-	       MarshalTypeRef=typeof(Efl.Eo.StringPassOwnershipMarshaler))]
+	       MarshalTypeRef=typeof(Efl.Eo.StringOutPassOwnershipMarshaler))]
     internal static extern string eina_strbuf_string_steal(IntPtr buf);
 
     [DllImport(efl.Libs.Eina, CharSet=CharSet.Ansi)]
     [return:
      MarshalAs(UnmanagedType.CustomMarshaler,
-	       MarshalTypeRef=typeof(Efl.Eo.StringKeepOwnershipMarshaler))]
+	       MarshalTypeRef=typeof(Efl.Eo.StringOutKeepOwnershipMarshaler))]
     internal static extern string eina_strbuf_string_get(IntPtr buf);
 
     [DllImport(efl.Libs.Eina)]

src/bindings/mono/eina_mono/eina_value.cs

@@ -194,7 +194,7 @@ static internal class UnsafeNativeMethods
     [DllImport(efl.Libs.Eina, CharSet=CharSet.Ansi)]
     [return:
      MarshalAs(UnmanagedType.CustomMarshaler,
-	       MarshalTypeRef=typeof(Efl.Eo.StringPassOwnershipMarshaler))]
+	       MarshalTypeRef=typeof(Efl.Eo.StringOutPassOwnershipMarshaler))]
     internal static extern string eina_value_to_string(IntPtr handle); // We take ownership of the returned string.
 
     [DllImport(efl.Libs.CustomExports)]

src/bindings/mono/eo_mono/StringMarshalers.cs

@@ -5,8 +5,12 @@ namespace Efl
 {
     namespace Eo
     {
-        class StringPassOwnershipMarshaler : ICustomMarshaler
+        /// <summary>
+        /// Marshaler for <c>@in</c> parameters that have their ownership transfered.
+        /// </summary>
+        class StringInPassOwnershipMarshaler : ICustomMarshaler
         {
+            // Called when C calls a C# method passing data to it
             public object MarshalNativeToManaged(IntPtr pNativeData)
             {
                 var ret = Eina.StringConversion.NativeUtf8ToManagedString(pNativeData);
@@ -14,16 +18,18 @@ namespace Efl
                 return ret;
             }
 
+            // Called when C# calls a C method passing data to it
             public IntPtr MarshalManagedToNative(object managedObj)
             {
                 return Eina.MemoryNative.StrDup((string)managedObj);
             }
 
+            // Called when the C call returns, cleaning the result from MarshalManagedToNative
             public void CleanUpNativeData(IntPtr pNativeData)
             {
-                // No need to cleanup. C will take care of it.
             }
 
+            // Called when the C# call returns, cleaning the result from MarshalNativeToManaged
             public void CleanUpManagedData(object managedObj)
             {
             }
@@ -37,32 +43,86 @@ namespace Efl
             {
                 if (marshaler == null)
                 {
-                    marshaler = new StringPassOwnershipMarshaler();
+                    marshaler = new StringInPassOwnershipMarshaler();
                 }
 
                 return marshaler;
             }
 
-            static private StringPassOwnershipMarshaler marshaler;
+            static private ICustomMarshaler marshaler;
         }
 
-        class StringKeepOwnershipMarshaler: ICustomMarshaler
+        /// <summary>
+        /// Marshaler for <c>@in</c> parameters that do not change their ownership.
+        /// </summary>
+        class StringInKeepOwnershipMarshaler: ICustomMarshaler
         {
+            // Called when C calls a C# method passing data to it
             public object MarshalNativeToManaged(IntPtr pNativeData)
             {
                 return Eina.StringConversion.NativeUtf8ToManagedString(pNativeData);
             }
 
+            // Called when C# calls a C method passing data to it
             public IntPtr MarshalManagedToNative(object managedObj)
             {
                 return Eina.StringConversion.ManagedStringToNativeUtf8Alloc((string)managedObj);
             }
 
+            // Called when the C call returns, cleaning the result from MarshalManagedToNative
             public void CleanUpNativeData(IntPtr pNativeData)
             {
-                // No need to free. The Native side will keep the ownership.
+                Eina.MemoryNative.Free(pNativeData);
             }
 
+            // Called when the C# call returns, cleaning the result from MarshalNativeToManaged
+            public void CleanUpManagedData(object managedObj)
+            {
+                // GC will should take care of it.
+            }
+
+            public int GetNativeDataSize()
+            {
+                return -1;
+            }
+
+            internal static ICustomMarshaler GetInstance(string cookie)
+            {
+                if (marshaler == null)
+                {
+                    marshaler = new StringInKeepOwnershipMarshaler();
+                }
+
+                return marshaler;
+            }
+
+            static private ICustomMarshaler marshaler;
+        }
+
+        class StringOutPassOwnershipMarshaler : ICustomMarshaler
+        {
+            // Called when C# calls a C method and receives data from it
+            public object MarshalNativeToManaged(IntPtr pNativeData)
+            {
+                var ret = Eina.StringConversion.NativeUtf8ToManagedString(pNativeData);
+                // C gave us ownership. Let's free.
+                Eina.MemoryNative.Free(pNativeData);
+                return ret;
+            }
+
+            // Called when C calls a C# method and receives data from it
+            public IntPtr MarshalManagedToNative(object managedObj)
+            {
+                // As we're passing up the ownership, no need to free it.
+                return Eina.MemoryNative.StrDup((string)managedObj);
+            }
+
+            // Called when the C call returns, cleaning the result it gave to C#
+            public void CleanUpNativeData(IntPtr pNativeData)
+            {
+            }
+
+            // Called when the C# call returns, cleaning the result it gave to C.
             public void CleanUpManagedData(object managedObj)
             {
             }
@@ -76,13 +136,57 @@ namespace Efl
             {
                 if (marshaler == null)
                 {
-                    marshaler = new StringKeepOwnershipMarshaler();
+                    marshaler = new StringOutPassOwnershipMarshaler();
                 }
 
                 return marshaler;
             }
 
-            static private StringKeepOwnershipMarshaler marshaler;
+            static private ICustomMarshaler marshaler;
+        }
+
+        class StringOutKeepOwnershipMarshaler: ICustomMarshaler
+        {
+            // Called when C# calls a C method and receives data from it
+            public object MarshalNativeToManaged(IntPtr pNativeData)
+            {
+                return Eina.StringConversion.NativeUtf8ToManagedString(pNativeData);
+            }
+
+            // Called when C calls a C# method and receives data from it
+            public IntPtr MarshalManagedToNative(object managedObj)
+            {
+                // FIXME This will be the tricky one, as it can leak.
+                return Eina.StringConversion.ManagedStringToNativeUtf8Alloc((string)managedObj);
+            }
+
+            // Called when the C call returns, cleaning the result it gave to C#
+            public void CleanUpNativeData(IntPtr pNativeData)
+            {
+                // No need to free. The Native side will keep the ownership.
+            }
+
+            // Called when the C call returns, cleaning the result it gave to C#
+            public void CleanUpManagedData(object managedObj)
+            {
+            }
+
+            public int GetNativeDataSize()
+            {
+                return -1;
+            }
+
+            internal static ICustomMarshaler GetInstance(string cookie)
+            {
+                if (marshaler == null)
+                {
+                    marshaler = new StringOutKeepOwnershipMarshaler();
+                }
+
+                return marshaler;
+            }
+
+            static private ICustomMarshaler marshaler;
         }
 
     }