kernel: add functions for moving sets of handles between tasks

kernel/handle.c

@@ -185,5 +185,129 @@ struct handle *handle_table_get_handle(
 		return NULL;
 	}
 
+	if (!tab->t_handles.t_handle_list[handle_index].h_object) {
+		return NULL;
+	}
+
 	return &tab->t_handles.t_handle_list[handle_index];
 }
+
+struct handle_list_iterator {
+	struct handle_list *it_list;
+	size_t it_list_count;
+	size_t it_list_ptr;
+
+	kern_handle_t *it_handles;
+	size_t it_nr_handles;
+};
+
+static void handle_list_iterator_begin(
+	struct handle_list_iterator *it,
+	struct handle_list *list,
+	size_t list_count)
+{
+	memset(it, 0x0, sizeof *it);
+	it->it_list = list;
+	it->it_list_count = list_count;
+
+	while (it->it_list_ptr < list_count) {
+		if (list[it->it_list_ptr].l_nr_handles > 0) {
+			break;
+		}
+
+		it->it_list_ptr++;
+	}
+
+	if (it->it_list_ptr >= list_count) {
+		return;
+	}
+
+	it->it_handles = list[it->it_list_ptr].l_handles;
+	it->it_nr_handles = list[it->it_list_ptr].l_nr_handles;
+}
+
+static void handle_list_iterator_seek(
+	struct handle_list_iterator *it,
+	size_t nr_handles)
+{
+	if (nr_handles > it->it_nr_handles) {
+		nr_handles = it->it_nr_handles;
+	}
+
+	if (nr_handles < it->it_nr_handles) {
+		it->it_handles += nr_handles;
+		it->it_nr_handles -= nr_handles;
+		return;
+	}
+
+	it->it_list_ptr++;
+	while (it->it_list_ptr < it->it_list_count) {
+		if (it->it_list[it->it_list_ptr].l_nr_handles > 0) {
+			break;
+		}
+
+		it->it_list_ptr++;
+	}
+
+	if (it->it_list_ptr >= it->it_list_count) {
+		return;
+	}
+
+	it->it_handles = it->it_list[it->it_list_ptr].l_handles;
+	it->it_nr_handles = it->it_list[it->it_list_ptr].l_nr_handles;
+}
+
+kern_status_t handle_list_transfer(
+	struct handle_table *dest_table,
+	struct handle_list *dest_list,
+	size_t dest_list_count,
+	struct handle_table *src_table,
+	const struct handle_list *src_list,
+	size_t src_list_count)
+{
+	struct handle_list_iterator src, dest;
+	handle_list_iterator_begin(
+		&src,
+		(struct handle_list *)src_list,
+		src_list_count);
+	handle_list_iterator_begin(&dest, dest_list, dest_list_count);
+
+	while (src.it_nr_handles && dest.it_nr_handles) {
+		size_t to_copy = MIN(src.it_nr_handles, dest.it_nr_handles);
+		for (size_t i = 0; i < to_copy; i++) {
+			kern_handle_t handle_v = src.it_handles[i];
+			struct handle *handle
+				= handle_table_get_handle(src_table, handle_v);
+			if (!handle) {
+				return KERN_HANDLE_INVALID;
+			}
+
+			struct object *obj = object_ref(handle->h_object);
+			handle_flags_t flags = handle->h_flags;
+
+			handle_table_free_handle(src_table, handle_v);
+
+			struct handle *dest_slot = NULL;
+			kern_status_t status = handle_table_alloc_handle(
+				dest_table,
+				&dest_slot,
+				&handle_v);
+			if (status != KERN_OK) {
+				return status;
+			}
+
+			dest_slot->h_object = obj;
+			dest_slot->h_flags = flags;
+
+			object_add_handle(obj);
+			object_unref(obj);
+
+			dest.it_handles[i] = handle_v;
+		}
+
+		handle_list_iterator_seek(&src, to_copy);
+		handle_list_iterator_seek(&dest, to_copy);
+	}
+
+	return KERN_OK;
+}