Don't use strlen() on a NULL pointer.

A bug introduced in commit 667b1bac77b134cf32c98d5dc25619e8c3303f52 caused tinc
to crash on startup.

diff --git a/src/conf.c b/src/conf.c
index 1b8213c..0727953 100644 (file)
--- a/src/conf.c
+++ b/src/conf.c
@@ -339,7 +339,7 @@ bool read_config_file(avl_tree_t *config_tree, const char *fname) {
 
 void read_config_options(avl_tree_t *config_tree, const char *prefix) {
        list_node_t *node, *next;
-       size_t prefix_len = strlen(prefix);
+       size_t prefix_len = prefix ? strlen(prefix) : 0;
 
        for(node = cmdline_conf->tail; node; node = next) {
                config_t *cfg = (config_t *)node->data;