selftests/bpf: Ensure consistent test failure output

printf() doesn't seem to honor using overwritten stdout/stderr (as part of
stdio hijacking), so ensure all "standard" invocations of printf() do
fprintf(stdout, ...) instead.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200313172336.1879637-2-andriin@fb.com

tools/testing/selftests/bpf/test_progs.c

@@ -216,7 +216,7 @@ int bpf_find_map(const char *test, struct bpf_object *obj, const char *name)
 
 	map = bpf_object__find_map_by_name(obj, name);
 	if (!map) {
-		printf("%s:FAIL:map '%s' not found\n", test, name);
+		fprintf(stdout, "%s:FAIL:map '%s' not found\n", test, name);
 		test__fail();
 		return -1;
 	}
@@ -387,7 +387,7 @@ static int libbpf_print_fn(enum libbpf_print_level level,
 {
 	if (env.verbosity < VERBOSE_VERY && level == LIBBPF_DEBUG)
 		return 0;
-	vprintf(format, args);
+	vfprintf(stdout, format, args);
 	return 0;
 }
 
@@ -633,7 +633,7 @@ int cd_flavor_subdir(const char *exec_name)
 	if (!flavor)
 		return 0;
 	flavor++;
-	printf("Switching to flavor '%s' subdirectory...\n", flavor);
+	fprintf(stdout, "Switching to flavor '%s' subdirectory...\n", flavor);
 	return chdir(flavor);
 }
 
@@ -716,7 +716,7 @@ int main(int argc, char **argv)
 			cleanup_cgroup_environment();
 	}
 	stdio_restore();
-	printf("Summary: %d/%d PASSED, %d SKIPPED, %d FAILED\n",
+	fprintf(stdout, "Summary: %d/%d PASSED, %d SKIPPED, %d FAILED\n",
 		env.succ_cnt, env.sub_succ_cnt, env.skip_cnt, env.fail_cnt);
 
 	free(env.test_selector.blacklist.strs);

tools/testing/selftests/bpf/test_progs.h

@@ -109,10 +109,10 @@ extern struct ipv6_packet pkt_v6;
 	int __save_errno = errno;					\
 	if (__ret) {							\
 		test__fail();						\
-		printf("%s:FAIL:%s ", __func__, tag);			\
-		printf(format);						\
+		fprintf(stdout, "%s:FAIL:%s ", __func__, tag);		\
+		fprintf(stdout, ##format);				\
 	} else {							\
-		printf("%s:PASS:%s %d nsec\n",				\
+		fprintf(stdout, "%s:PASS:%s %d nsec\n",			\
 		       __func__, tag, duration);			\
 	}								\
 	errno = __save_errno;						\
@@ -124,7 +124,7 @@ extern struct ipv6_packet pkt_v6;
 	int __save_errno = errno;					\
 	if (__ret) {							\
 		test__fail();						\
-		printf("%s:FAIL:%d\n", __func__, __LINE__);		\
+		fprintf(stdout, "%s:FAIL:%d\n", __func__, __LINE__);	\
 	}								\
 	errno = __save_errno;						\
 	__ret;								\