ast: store function declarations as opcode offsets

We cannot use direct pointers since the opcode array might be reallocated
resulting in potentially changed memory addresses.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

3 files changed, 10 insertions, 6 deletions

diff --git a/ast.c b/ast.c
index 80a878e..2ac6714 100644
--- a/ast.c
+++ b/ast.c
@@ -285,13 +285,11 @@ func_to_string(struct json_object *v, struct printbuf *pb, int level, int flags)
 	struct ut_op *op = json_object_get_userdata(v);
 	struct ut_op *base, *decl, *name, *args, *arg;
 
-	if (!op->tag.data)
-		return 0;
-
 	/* find start of operand array */
-	for (decl = op->tag.data, base = decl; base && !base->is_first; base--)
+	for (base = op; base && !base->is_first; base--)
 		;
 
+	decl = base + (op->tag.off ? op->tag.off - 1 : 0);
 	name = base + (decl->tree.operand[0] ? decl->tree.operand[0] - 1 : 0);
 	args = base + (decl->tree.operand[1] ? decl->tree.operand[1] - 1 : 0);
 
@@ -313,10 +311,15 @@ ut_new_func(struct ut_op *decl)
 {
 	struct json_object *val = xjs_new_object();
 	struct ut_op *op = xalloc(sizeof(*op));
+	struct ut_op *base;
+
+	/* find start of operand array */
+	for (base = decl; base && !base->is_first; base--)
+		;
 
 	op->val = val;
 	op->type = T_FUNC;
-	op->tag.data = decl;
+	op->tag.off = (decl - base) + 1;
 
 	json_object_set_serializer(val, func_to_string, op, obj_free);
 
diff --git a/ast.h b/ast.h
index 45032d5..3cf0b4f 100644
--- a/ast.h
+++ b/ast.h
@@ -72,6 +72,7 @@ struct ut_op {
 			struct json_object *proto;
 			size_t type;
 			void *data;
+			uint32_t off;
 		} tag;
 		struct {
 			uint32_t next;
diff --git a/eval.c b/eval.c
index cfee806..c7cad75 100644
--- a/eval.c
+++ b/eval.c
@@ -1050,7 +1050,7 @@ ut_invoke(struct ut_state *state, uint32_t off, struct json_object *scope,
 		return cfn ? cfn(state, off, argvals) : NULL;
 	}
 
-	decl = tag->tag.data;
+	decl = ut_get_op(state, tag->tag.off);
 	arg = ut_get_op(state, decl ? decl->tree.operand[1] : 0);
 
 	s = scope ? scope : ut_addscope(state, ut_get_off(state, decl));