Handle the ENOENT error

fakeid.c

@@ -24,7 +24,11 @@ char *getlogin(void) {
 }
 
 int getlogin_r(char *buf, size_t bufsize) {
-    return strlcpy(buf, getlogin(), bufsize);
+    const char *login = getlogin();
+    if (login == NULL) {
+        return ENOENT;
+    }
+    return strlcpy(buf, login, bufsize);
 }
 
 struct passwd *getpwuid(uid_t uid) {