tal/autoptr: new module.

[ccan] / ccan / tal / autoptr / autoptr.c

diff --git a/ccan/tal/autoptr/autoptr.c b/ccan/tal/autoptr/autoptr.c
new file mode 100644 (file)
index 0000000..5f22ef2
--- /dev/null
+++ b/ccan/tal/autoptr/autoptr.c
@@ -0,0 +1,35 @@
+/* MIT (BSD) license - see LICENSE file for details */
+#include <ccan/tal/autoptr/autoptr.h>
+
+struct autonull {
+       void **pp;
+};
+
+static void autonull_remove(struct autonull *a);
+static void autonull_null_out(tal_t *p UNNEEDED, struct autonull *a)
+{
+       void **pp = a->pp;
+       tal_del_destructor(a, autonull_remove);
+       tal_free(a);
+       *pp = NULL;
+}
+
+static void autonull_remove(struct autonull *a)
+{
+       /* Don't NULL us out now. */
+       tal_del_destructor2(*a->pp, autonull_null_out, a);
+}
+
+struct autonull *autonull_set_ptr_(const tal_t *ctx, void *pp, const tal_t *p)
+{
+       struct autonull *a = tal(ctx, struct autonull);
+       a->pp = (void **)pp;
+       *a->pp = (void *)p;
+
+       /* If p is freed, NULL out a->pp */
+       tal_add_destructor2(*a->pp, autonull_null_out, a);
+
+       /* If they free autonull, it removes other destructor. */
+       tal_add_destructor(a, autonull_remove);
+       return a;
+}