Add safety assert in parse_movement_unit

Let's add this just in case a caller passes argc == 0.

References: https://github.com/swaywm/sway/issues/6737#issuecomment-1008082540

1 files changed, 6 insertions, 0 deletions

diff --git a/common/util.c b/common/util.c
index 199f3ee1..5d4c0673 100644
--- a/common/util.c
+++ b/common/util.c
@@ -80,6 +80,12 @@ enum movement_unit parse_movement_unit(const char *unit) {
 
 int parse_movement_amount(int argc, char **argv,
                 struct movement_amount *amount) {
+        if (!sway_assert(argc > 0, "Expected args in parse_movement_amount")) {
+                amount->amount = 0;
+                amount->unit = MOVEMENT_UNIT_INVALID;
+                return 0;
+        }
+
         char *err;
         amount->amount = (int)strtol(argv[0], &err, 10);
         if (*err) {