# HG changeset patch
# User Guido Berhoerster <guido+pwm@berhoerster.name>
# Date 1564511888 -7200
# Node ID fa93d2ff9c6283c11479d1f4d121ff6962e0557c
# Parent  b5ebed168e591bf76a700ed3e2ec94dcdde6db19
Prevent potential division by zero

Add safeguard ensuring that there is at least one possible character to
generate passwords from in order to exclude the possibility of a division by
zero error in rand_uniform.

diff -r b5ebed168e59 -r fa93d2ff9c62 pw.c
--- a/pw.c	Tue Nov 28 17:16:24 2017 +0100
+++ b/pw.c	Tue Jul 30 20:38:08 2019 +0200
@@ -56,6 +56,10 @@
 	for (i = 0; i < groups_len; i++) {
 		chars_len += strlen(groups[i].chars);
 	}
+	if (chars_len == 0) {
+		/* there must be at least one character to choose from */
+		return (-1);
+	}
 
 	chars = xmalloc(chars_len + 1);
 	chars[0] = '\0';