ast, eval: add recursion limit

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

4 files changed, 37 insertions, 3 deletions

diff --git a/ast.c b/ast.c
index 72fa6e9..2e1c169 100644
--- a/ast.c
+++ b/ast.c
@@ -405,7 +405,7 @@ add_stacktrace(struct json_object *a, struct ut_source *source, const char *func
 __attribute__((format(printf, 3, 4))) struct json_object *
 ut_new_exception(struct ut_state *s, uint32_t off, const char *fmt, ...)
 {
-	struct ut_callstack *callstack;
+	struct ut_callstack *callstack, *prevcall;
 	struct json_object *a;
 	struct ut_op *op;
 	va_list ap;
@@ -425,8 +425,11 @@ ut_new_exception(struct ut_state *s, uint32_t off, const char *fmt, ...)
 	               s->function ? s->function->name : NULL,
 	               off);
 
-	for (callstack = s->callstack ? s->callstack->next : NULL; callstack; callstack = callstack->next)
-		if (callstack->off)
+	for (callstack = s->callstack ? s->callstack->next : NULL, prevcall = NULL;
+	     callstack != NULL;
+	     prevcall = callstack, callstack = callstack->next)
+		if (callstack->off &&
+		    (!prevcall || callstack->source != prevcall->source || callstack->off != prevcall->off))
 			add_stacktrace(a, callstack->source, callstack->funcname, callstack->off);
 
 	json_object_object_add(op->val, "stacktrace", a);
diff --git a/ast.h b/ast.h
index f86d93f..26eee73 100644
--- a/ast.h
+++ b/ast.h
@@ -135,6 +135,7 @@ struct ut_state {
 	struct ut_source *sources, *source;
 	struct ut_callstack *callstack;
 	struct ut_function *function;
+	size_t calldepth;
 };
 
 struct ut_extended_type {
diff --git a/eval.c b/eval.c
index 2230bb9..3d76774 100644
--- a/eval.c
+++ b/eval.c
@@ -981,12 +981,16 @@ ut_invoke(struct ut_state *state, uint32_t off, struct json_object *this,
 
 	op = ut_get_op(state, off);
 
+	if (state->calldepth >= 1000)
+		return ut_new_exception(state, op->off, "Runtime error: Too much recursion");
+
 	callstack.next = state->callstack;
 	callstack.source = state->source;
 	callstack.funcname = state->function ? state->function->name : NULL;
 	callstack.off = op ? op->off : 0;
 	callstack.ctx = json_object_get(this ? this : state->ctx);
 	state->callstack = &callstack;
+	state->calldepth++;
 
 	/* is native function */
 	if (tag->type == T_CFUNC) {
@@ -1042,6 +1046,7 @@ ut_invoke(struct ut_state *state, uint32_t off, struct json_object *this,
 
 	json_object_put(callstack.ctx);
 	state->callstack = callstack.next;
+	state->calldepth--;
 
 	return rv;
 }
diff --git a/tests/02_runtime/06_recursion b/tests/02_runtime/06_recursion
index e707c86..028feba 100644
--- a/tests/02_runtime/06_recursion
+++ b/tests/02_runtime/06_recursion
@@ -33,3 +33,28 @@ Testing recursive invocations.
 	test(1);
 %}
 -- End --
+
+
+2. Testing infinite recursion.
+
+-- Expect stderr --
+Runtime error: Too much recursion
+In test(), line 3, byte 7:
+  at function test ([stdin]:3:7)
+  at main function ([stdin]:6:6)
+
+ `        test();`
+  Near here --^
+
+
+-- End --
+
+-- Testcase --
+{%
+	function test() {
+		test();
+	}
+
+	test();
+%}
+-- End --