Fix crash during initialization

Randomization code that swaps two string values using strlcpy(3)
during initialization frequently selected the same string as both the
source and the destination. This is supported on NetBSD but results in
undefined behavior on other BSD-derived systems. As a result, the
program usually crashed during startup during testing on macOS. Fix it
by ensuring that the two random values differ.

1 files changed, 5 insertions, 1 deletions

diff --git a/inventory.c b/inventory.c
index 934e8aa..83d69a5 100644
--- a/inventory.c
+++ b/inventory.c
@@ -431,7 +431,11 @@ mix_colors(void)
 
 	for (i = 0; i <= 32; i++) {
 		j = get_rand(0, (POTIONS - 1));
-		k = get_rand(0, (POTIONS - 1));
+		k = get_rand(0, (POTIONS - 2));
+		if (k >= j) {
+			k++;
+		}
+
 		strlcpy(t, id_potions[j].title, sizeof(t));
 		strlcpy(id_potions[j].title, id_potions[k].title,
 			sizeof(id_potions[j].title));