fuzz: unify logging setup

Make sure we don't log anything when running in "fuzzing" mode. Also,
when at it, unify the setup logic into a helper, pretty similar to
the test_setup_logging() one.

Addresses:
  - https://github.com/systemd/systemd/pull/29558#pullrequestreview-1676060607
  - https://github.com/systemd/systemd/pull/29558#discussion_r1358940663

src/fuzz/fuzz-bootspec.c

@@ -87,9 +87,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         if (outside_size_range(size, 0, 65536))
                 return 0;
 
-        /* Disable most logging if not running standalone */
-        if (!getenv("SYSTEMD_LOG_LEVEL"))
-                log_set_max_level(LOG_CRIT);
+        fuzz_setup_logging();
 
         assert_se(datadup = memdup_suffix0(data, size));
 

src/fuzz/fuzz-bus-label.c

@@ -9,6 +9,8 @@
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         _cleanup_free_ char *unescaped = NULL, *escaped = NULL;
 
+        fuzz_setup_logging();
+
         unescaped = bus_label_unescape_n((const char*)data, size);
         assert_se(unescaped != NULL);
         escaped = bus_label_escape(unescaped);

src/fuzz/fuzz-calendarspec.c

@@ -12,8 +12,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         _cleanup_free_ char *str = NULL;
         int r;
 
-        if (!getenv("SYSTEMD_LOG_LEVEL"))
-                log_set_max_level(LOG_CRIT);
+        fuzz_setup_logging();
 
         assert_se(str = memdup_suffix0(data, size));
 

src/fuzz/fuzz-catalog.c

@@ -11,8 +11,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         _cleanup_close_ int fd = -EBADF;
         _cleanup_ordered_hashmap_free_free_free_ OrderedHashmap *h = NULL;
 
-        if (!getenv("SYSTEMD_LOG_LEVEL"))
-                log_set_max_level(LOG_CRIT);
+        fuzz_setup_logging();
 
         assert_se(h = ordered_hashmap_new(&catalog_hash_ops));
 

src/fuzz/fuzz-compress.c

@@ -29,10 +29,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
 
         int alg = h->alg;
 
-        /* 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);
+        fuzz_setup_logging();
 
         log_info("Using compression %s, data size=%zu",
                  compression_to_string(alg),

src/fuzz/fuzz-env-file.c

@@ -18,10 +18,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         f = data_to_file(data, size);
         assert_se(f);
 
-        /* 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);
+        fuzz_setup_logging();
 
         (void) load_env_file(f, NULL, &rl);
         assert_se(fseek(f, 0, SEEK_SET) == 0);

src/fuzz/fuzz-hostname-setup.c

@@ -12,10 +12,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         f = data_to_file(data, size);
         assert_se(f);
 
-        /* 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);
+        fuzz_setup_logging();
 
         (void) read_etc_hostname_stream(f, &ret);
 

src/fuzz/fuzz-json.c

@@ -14,9 +14,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         FILE *g = NULL;
         int r;
 
-        /* Disable most logging if not running standalone */
-        if (!getenv("SYSTEMD_LOG_LEVEL"))
-                log_set_max_level(LOG_CRIT);
+        fuzz_setup_logging();
 
         f = data_to_file(data, size);
         assert_se(f);

src/fuzz/fuzz-time-util.c

@@ -9,8 +9,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         _cleanup_free_ char *str = NULL;
         usec_t usec;
 
-        if (!getenv("SYSTEMD_LOG_LEVEL"))
-                log_set_max_level(LOG_CRIT);
+        fuzz_setup_logging();
 
         assert_se(str = memdup_suffix0(data, size));
 

src/fuzz/fuzz-udev-database.c

@@ -12,8 +12,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         _cleanup_(unlink_tempfilep) char filename[] = "/tmp/fuzz-udev-database.XXXXXX";
         _cleanup_fclose_ FILE *f = NULL;
 
-        if (!getenv("SYSTEMD_LOG_LEVEL"))
-                log_set_max_level(LOG_CRIT);
+        fuzz_setup_logging();
 
         assert_se(fmkostemp_safe(filename, "r+", &f) == 0);
         if (size != 0)

src/fuzz/fuzz-varlink-idl.c

@@ -14,9 +14,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         _cleanup_free_ char *str = NULL, *dump = NULL;
         int r;
 
-        log_set_max_level(LOG_CRIT);
-        log_parse_environment();
-        (void) log_open();
+        fuzz_setup_logging();
 
         assert_se(str = memdup_suffix0(data, size));
 

src/fuzz/fuzz-varlink.c

@@ -92,8 +92,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
         _cleanup_(varlink_flush_close_unrefp) Varlink *c = NULL;
         _cleanup_(sd_event_unrefp) sd_event *e = NULL;
 
-        log_set_max_level(LOG_CRIT);
-        log_parse_environment();
+        fuzz_setup_logging();
 
         assert_se(null = fopen("/dev/null", "we"));
 

src/fuzz/fuzz.h

@@ -28,5 +28,13 @@ static inline bool outside_size_range(size_t size, size_t lower, size_t upper) {
         return false;
 }
 
+static inline void fuzz_setup_logging(void) {
+        /* We don't want to fill the logs and slow down stuff when running
+         * in a fuzzing mode, so disable most of the logging. */
+        log_set_max_level(LOG_CRIT);
+        log_parse_environment();
+        log_open();
+}
+
 /* Force value to not be optimized away. */
 #define DO_NOT_OPTIMIZE(value) ({ asm volatile("" : : "g"(value) : "memory"); })