Fix crash when starting without HOME

If HOME environment variable is not set, sway fails startup with a
segmentation fault due to null pointer dereference.

Also check calloc return value and only perform the fallback code when
really needed.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>

1 files changed, 6 insertions, 4 deletions

diff --git a/sway/config.c b/sway/config.c
index 39013865..fde386c7 100644
--- a/sway/config.c
+++ b/sway/config.c
@@ -354,12 +354,14 @@ static char *config_path(const char *prefix, const char *config_folder) {
 static char *get_config_path(void) {
         char *path = NULL;
         const char *home = getenv("HOME");
-        size_t size_fallback = 1 + strlen(home) + strlen("/.config");
-        char *config_home_fallback = calloc(size_fallback, sizeof(char));
-        snprintf(config_home_fallback, size_fallback, "%s/.config", home);
+        char *config_home_fallback = NULL;
 
         const char *config_home = getenv("XDG_CONFIG_HOME");
-        if (config_home == NULL || config_home[0] == '\0') {
+        if ((config_home == NULL || config_home[0] == '\0') && home != NULL) {
+                size_t size_fallback = 1 + strlen(home) + strlen("/.config");
+                config_home_fallback = calloc(size_fallback, sizeof(char));
+                if (config_home_fallback != NULL)
+                        snprintf(config_home_fallback, size_fallback, "%s/.config", home);
                 config_home = config_home_fallback;
         }