Log empty value if envvar is not defined

If the environment variable is not defined, getenv returns NULL.
Passing a NULL pointer to the "%s" format specifier is undefined
behavior. Even if some implementations output "(null)", an empty
string is nicer.

1 files changed, 2 insertions, 1 deletions

diff --git a/sway/main.c b/sway/main.c
index d893654f..57716071 100644
--- a/sway/main.c
+++ b/sway/main.c
@@ -138,7 +138,8 @@ static void log_env(void) {
                 "SWAYSOCK",
         };
         for (size_t i = 0; i < sizeof(log_vars) / sizeof(char *); ++i) {
-                sway_log(SWAY_INFO, "%s=%s", log_vars[i], getenv(log_vars[i]));
+                char *value = getenv(log_vars[i]);
+                sway_log(SWAY_INFO, "%s=%s", log_vars[i], value != NULL ? value : "");
         }
 }