+
+/**
+ * mono_method_get_base_method:
+ * @method: a method
+ * @definition: if true, get the definition
+ * @error: set on failure
+ *
+ * Given a virtual method associated with a subclass, return the corresponding
+ * method from an ancestor. If @definition is FALSE, returns the method in the
+ * superclass of the given method. If @definition is TRUE, return the method
+ * in the ancestor class where it was first declared. The type arguments will
+ * be inflated in the ancestor classes. If the method is not associated with a
+ * class, or isn't virtual, returns the method itself. On failure returns NULL
+ * and sets @error.
+ */
+MonoMethod*
+mono_method_get_base_method (MonoMethod *method, gboolean definition, MonoError *error)
+{
+ MonoClass *klass, *parent;
+ MonoGenericContext *generic_inst = NULL;
+ MonoMethod *result = NULL;
+ int slot;
+
+ if (method->klass == NULL)
+ return method;
+
+ if (!(method->flags & METHOD_ATTRIBUTE_VIRTUAL) ||
+ MONO_CLASS_IS_INTERFACE (method->klass) ||
+ method->flags & METHOD_ATTRIBUTE_NEW_SLOT)
+ return method;
+
+ slot = mono_method_get_vtable_slot (method);
+ if (slot == -1)
+ return method;
+
+ klass = method->klass;
+ if (mono_class_is_ginst (klass)) {
+ generic_inst = mono_class_get_context (klass);
+ klass = mono_class_get_generic_class (klass)->container_class;
+ }
+
+retry:
+ if (definition) {
+ /* At the end of the loop, klass points to the eldest class that has this virtual function slot. */
+ for (parent = klass->parent; parent != NULL; parent = parent->parent) {
+ /* on entry, klass is either a plain old non-generic class and generic_inst == NULL
+ or klass is the generic container class and generic_inst is the instantiation.
+
+ when we go to the parent, if the parent is an open constructed type, we need to
+ replace the type parameters by the definitions from the generic_inst, and then take it
+ apart again into the klass and the generic_inst.
+
+ For cases like this:
+ class C<T> : B<T, int> {
+ public override void Foo () { ... }
+ }
+ class B<U,V> : A<HashMap<U,V>> {
+ public override void Foo () { ... }
+ }
+ class A<X> {
+ public virtual void Foo () { ... }
+ }
+
+ if at each iteration the parent isn't open, we can skip inflating it. if at some
+ iteration the parent isn't generic (after possible inflation), we set generic_inst to
+ NULL;
+ */
+ MonoGenericContext *parent_inst = NULL;
+ if (mono_class_is_open_constructed_type (mono_class_get_type (parent))) {
+ parent = mono_class_inflate_generic_class_checked (parent, generic_inst, error);
+ return_val_if_nok (error, NULL);
+ }
+ if (mono_class_is_ginst (parent)) {
+ parent_inst = mono_class_get_context (parent);
+ parent = mono_class_get_generic_class (parent)->container_class;
+ }
+
+ mono_class_setup_vtable (parent);
+ if (parent->vtable_size <= slot)
+ break;
+ klass = parent;
+ generic_inst = parent_inst;
+ }
+ } else {
+ klass = klass->parent;
+ if (!klass)
+ return method;
+ if (mono_class_is_open_constructed_type (mono_class_get_type (klass))) {
+ klass = mono_class_inflate_generic_class_checked (klass, generic_inst, error);
+ return_val_if_nok (error, NULL);
+
+ generic_inst = NULL;
+ }
+ if (mono_class_is_ginst (klass)) {
+ generic_inst = mono_class_get_context (klass);
+ klass = mono_class_get_generic_class (klass)->container_class;
+ }
+
+ }
+
+ if (generic_inst) {
+ klass = mono_class_inflate_generic_class_checked (klass, generic_inst, error);
+ return_val_if_nok (error, NULL);
+ }
+
+ if (klass == method->klass)
+ return method;
+
+ /*This is possible if definition == FALSE.
+ * Do it here to be really sure we don't read invalid memory.
+ */
+ if (slot >= klass->vtable_size)
+ return method;
+
+ mono_class_setup_vtable (klass);
+
+ result = klass->vtable [slot];
+ if (result == NULL) {
+ /* It is an abstract method */
+ gboolean found = FALSE;
+ gpointer iter = NULL;
+ while ((result = mono_class_get_methods (klass, &iter))) {
+ if (result->slot == slot) {
+ found = TRUE;
+ break;
+ }
+ }
+ /* found might be FALSE if we looked in an abstract class
+ * that doesn't override an abstract method of its
+ * parent:
+ * abstract class Base {
+ * public abstract void Foo ();
+ * }
+ * abstract class Derived : Base { }
+ * class Child : Derived {
+ * public override void Foo () { }
+ * }
+ *
+ * if m was Child.Foo and we ask for the base method,
+ * then we get here with klass == Derived and found == FALSE
+ */
+ /* but it shouldn't be the case that if we're looking
+ * for the definition and didn't find a result; the
+ * loop above should've taken us as far as we could
+ * go! */
+ g_assert (!(definition && !found));
+ if (!found)
+ goto retry;
+ }
+
+ g_assert (result != NULL);
+ return result;
+}