[gjs] add support for (out caller-allocates)

[Colin Walters <walters src gnome org>]

commit fd1b655863610832f65077bcf08a0c560b14d83b
Author: Maxim Ermilov <zaspire rambler ru>
Date:   Thu Aug 12 02:17:01 2010 +0400

    add support for (out caller-allocates)
    
    Modified to clean up memory leaks and add comments
    by Colin Walters <walters verbum org>.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=624811

 gi/function.c                         |   76 ++++++++++++++++++++++++++++++++-
 test/js/testEverythingEncapsulated.js |   14 ++++++
 2 files changed, 88 insertions(+), 2 deletions(-)
---
diff --git a/gi/function.c b/gi/function.c
index 0404bdf..e83aa69 100644
--- a/gi/function.c
+++ b/gi/function.c
@@ -497,8 +497,49 @@ gjs_invoke_c_function(JSContext      *context,
             g_assert_cmpuint(out_args_pos, <, out_args_len);
             g_assert_cmpuint(in_args_pos, <, in_args_len);
 
-            out_arg_cvalues[out_args_pos].v_pointer = NULL;
-            in_arg_cvalues[in_args_pos].v_pointer = &out_arg_cvalues[out_args_pos];
+            if (g_arg_info_is_caller_allocates(&arg_info)) {
+                GITypeTag type_tag;
+                GITypeInfo ainfo;
+
+                g_arg_info_load_type(&arg_info, &ainfo);
+                type_tag = g_type_info_get_tag(&ainfo);
+
+                switch (type_tag) {
+                case GI_TYPE_TAG_INTERFACE:
+                    {
+                        GIBaseInfo* interface_info;
+                        GIInfoType interface_type;
+                        gsize size;
+
+                        interface_info = g_type_info_get_interface(&ainfo);
+                        g_assert(interface_info != NULL);
+
+                        interface_type = g_base_info_get_type(interface_info);
+                        g_base_info_unref((GIBaseInfo*)interface_info);
+
+                        if (interface_type == GI_INFO_TYPE_STRUCT) {
+                            size = g_struct_info_get_size((GIStructInfo*)interface_info);
+                        } else if (interface_type == GI_INFO_TYPE_UNION) {
+                            size = g_union_info_get_size((GIUnionInfo*)interface_info);
+                        } else {
+                            failed = TRUE;
+                        }
+
+                        if (!failed) {
+                            in_arg_cvalues[in_args_pos].v_pointer = g_slice_alloc0(size);
+                            out_arg_cvalues[out_args_pos].v_pointer = in_arg_cvalues[in_args_pos].v_pointer;
+                        }
+                        break;
+                    }
+                default:
+                    failed = TRUE;
+                }
+                if (failed)
+                    gjs_throw(context, "Unsupported type %s for (out caller-allocates)", g_type_tag_to_string(type_tag));
+            } else {
+                out_arg_cvalues[out_args_pos].v_pointer = NULL;
+                in_arg_cvalues[in_args_pos].v_pointer = &out_arg_cvalues[out_args_pos];
+            }
             out_args_pos++;
         } else {
             GArgument *in_value;
@@ -696,6 +737,37 @@ release:
                 postinvoke_release_failed = TRUE;
             }
 
+            /* For caller-allocates, what happens here is we allocate
+             * a structure above, then gjs_value_from_g_argument calls
+             * g_boxed_copy on it, and takes ownership of that.  So
+             * here we release the memory allocated above.  It would be
+             * better to special case this and directly hand JS the boxed
+             * object and tell gjs_boxed it owns the memory, but for now
+             * this works OK.  We could also alloca() the structure instead
+             * of slice allocating.
+             */
+            if (g_arg_info_is_caller_allocates(&arg_info)) {
+                GITypeTag type_tag;
+                GIBaseInfo* interface_info;
+                GIInfoType interface_type;
+                gsize size;
+
+                type_tag = g_type_info_get_tag(&arg_type_info);
+                g_assert(type_tag == GI_TYPE_TAG_INTERFACE);
+                interface_info = g_type_info_get_interface(&arg_type_info);
+                interface_type = g_base_info_get_type(interface_info);
+                if (interface_type == GI_INFO_TYPE_STRUCT) {
+                    size = g_struct_info_get_size((GIStructInfo*)interface_info);
+                } else if (interface_type == GI_INFO_TYPE_UNION) {
+                    size = g_union_info_get_size((GIUnionInfo*)interface_info);
+                } else {
+                    g_assert_not_reached();
+                }
+
+                g_slice_free1(size, out_arg_cvalues[out_args_pos].v_pointer);
+                g_base_info_unref((GIBaseInfo*)interface_info);
+            }
+
             /* Free GArgument, the jsval should have ref'd or copied it */
             if (!arg_failed)
                 gjs_g_argument_release(context,
diff --git a/test/js/testEverythingEncapsulated.js b/test/js/testEverythingEncapsulated.js
index 8dd82c2..2e4a1b3 100644
--- a/test/js/testEverythingEncapsulated.js
+++ b/test/js/testEverythingEncapsulated.js
@@ -15,6 +15,20 @@ function testStruct() {
     assertEquals(43, struct.some_int8);
     assertEquals(42.5, struct.some_double);
     assertEquals(Everything.TestEnum.VALUE3, struct.some_enum);
+    let b = struct.clone();
+    assertEquals(42, b.some_int);
+    assertEquals(43, b.some_int8);
+    assertEquals(42.5, b.some_double);
+    assertEquals(Everything.TestEnum.VALUE3, b.some_enum);
+
+    struct = new Everything.TestStructB();
+    struct.some_int8 = 43;
+    struct.nested_a.some_int8 = 66;
+    assertEquals(43, struct.some_int8);
+    assertEquals(66, struct.nested_a.some_int8);
+    b = struct.clone();
+    assertEquals(43, b.some_int8);
+    assertEquals(66, struct.nested_a.some_int8);
 }
 
 function testStructConstructor()