fuzz: allow logging to be configured, disable in fuzz-unit-file

fuzz-unit-file generated too much logs about invalid config lines. This just
slows things down and fills the logs. If necessary, it's better to rerun the
interesting cases with SYSTEMD_LOG_LEVEL=debug.

Author: keszybz

src/fuzz/fuzz-main.c

@@ -33,6 +33,9 @@ int main(int argc, char **argv) {
         char *name;
 
         log_set_max_level(LOG_DEBUG);
+        log_parse_environment();
+        log_open();
+
         for (i = 1; i < argc; i++) {
                 _cleanup_free_ char *buf = NULL;
 
@@ -47,5 +50,6 @@ int main(int argc, char **argv) {
                 (void) LLVMFuzzerTestOneInput((uint8_t*)buf, size);
                 printf("ok\n");
         }
+
         return EXIT_SUCCESS;
 }

src/fuzz/fuzz-unit-file.c

@@ -35,6 +35,11 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         if (!unit_vtable[t]->load)
                 return 0;
 
+        /* We don't want to fill the logs with messages about parse errors.
+         * Disable most logging if not running standalone */
+        if (!getenv("SYSTEMD_LOG_LEVEL"))
+                log_set_max_level(LOG_CRIT);
+
         assert_se(manager_new(UNIT_FILE_SYSTEM, MANAGER_TEST_RUN_MINIMAL, &m) >= 0);
 
         name = strjoina("a.", unit_type_to_string(t));