Merge branch 'test_progs-stdio'

Stanislav Fomichev says:

====================
I was looking into converting test_sockops* to test_progs framework
and that requires using cgroup_helpers.c which rely on stdio/stderr.
Let's use open_memstream to override stdout into buffer during
subtests instead of custom test_{v,}printf wrappers. That lets
us continue to use stdio in the subtests and dump it on failure
if required.

That would also fix bpf_find_map which currently uses printf to
signal failure (missed during test_printf conversion).
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c

@@ -5,13 +5,13 @@ static int libbpf_debug_print(enum libbpf_print_level level,
 			      const char *format, va_list args)
 {
 	if (level != LIBBPF_DEBUG) {
-		test__vprintf(format, args);
+		vprintf(format, args);
 		return 0;
 	}
 
 	if (!strstr(format, "verifier log"))
 		return 0;
-	test__vprintf("%s", args);
+	vprintf("%s", args);
 	return 0;
 }
 

tools/testing/selftests/bpf/prog_tests/l4lb_all.c

@@ -74,7 +74,7 @@ static void test_l4lb(const char *file)
 	}
 	if (bytes != MAGIC_BYTES * NUM_ITER * 2 || pkts != NUM_ITER * 2) {
 		error_cnt++;
-		test__printf("test_l4lb:FAIL:stats %lld %lld\n", bytes, pkts);
+		printf("test_l4lb:FAIL:stats %lld %lld\n", bytes, pkts);
 	}
 out:
 	bpf_object__close(obj);

tools/testing/selftests/bpf/prog_tests/map_lock.c

@@ -9,12 +9,12 @@ static void *parallel_map_access(void *arg)
 	for (i = 0; i < 10000; i++) {
 		err = bpf_map_lookup_elem_flags(map_fd, &key, vars, BPF_F_LOCK);
 		if (err) {
-			test__printf("lookup failed\n");
+			printf("lookup failed\n");
 			error_cnt++;
 			goto out;
 		}
 		if (vars[0] != 0) {
-			test__printf("lookup #%d var[0]=%d\n", i, vars[0]);
+			printf("lookup #%d var[0]=%d\n", i, vars[0]);
 			error_cnt++;
 			goto out;
 		}
@@ -22,8 +22,8 @@ static void *parallel_map_access(void *arg)
 		for (j = 2; j < 17; j++) {
 			if (vars[j] == rnd)
 				continue;
-			test__printf("lookup #%d var[1]=%d var[%d]=%d\n",
-				     i, rnd, j, vars[j]);
+			printf("lookup #%d var[1]=%d var[%d]=%d\n",
+			       i, rnd, j, vars[j]);
 			error_cnt++;
 			goto out;
 		}
@@ -43,7 +43,7 @@ void test_map_lock(void)
 
 	err = bpf_prog_load(file, BPF_PROG_TYPE_CGROUP_SKB, &obj, &prog_fd);
 	if (err) {
-		test__printf("test_map_lock:bpf_prog_load errno %d\n", errno);
+		printf("test_map_lock:bpf_prog_load errno %d\n", errno);
 		goto close_prog;
 	}
 	map_fd[0] = bpf_find_map(__func__, obj, "hash_map");

tools/testing/selftests/bpf/prog_tests/send_signal.c

@@ -202,8 +202,8 @@ static int test_send_signal_nmi(void)
 			 -1 /* cpu */, -1 /* group_fd */, 0 /* flags */);
 	if (pmu_fd == -1) {
 		if (errno == ENOENT) {
-			test__printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n",
-				     __func__);
+			printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n",
+			       __func__);
 			return 0;
 		}
 		/* Let the test fail with a more informative message */

tools/testing/selftests/bpf/prog_tests/spinlock.c

@@ -12,7 +12,7 @@ void test_spinlock(void)
 
 	err = bpf_prog_load(file, BPF_PROG_TYPE_CGROUP_SKB, &obj, &prog_fd);
 	if (err) {
-		test__printf("test_spin_lock:bpf_prog_load errno %d\n", errno);
+		printf("test_spin_lock:bpf_prog_load errno %d\n", errno);
 		goto close_prog;
 	}
 	for (i = 0; i < 4; i++)

tools/testing/selftests/bpf/prog_tests/stacktrace_build_id.c

@@ -109,8 +109,8 @@ void test_stacktrace_build_id(void)
 	if (build_id_matches < 1 && retry--) {
 		bpf_link__destroy(link);
 		bpf_object__close(obj);
-		test__printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
-			     __func__);
+		printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
+		       __func__);
 		goto retry;
 	}
 

tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c

@@ -140,8 +140,8 @@ void test_stacktrace_build_id_nmi(void)
 	if (build_id_matches < 1 && retry--) {
 		bpf_link__destroy(link);
 		bpf_object__close(obj);
-		test__printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
-			     __func__);
+		printf("%s:WARN:Didn't find expected build ID from the map, retrying\n",
+		       __func__);
 		goto retry;
 	}
 

tools/testing/selftests/bpf/prog_tests/xdp_noinline.c

@@ -75,8 +75,8 @@ void test_xdp_noinline(void)
 	}
 	if (bytes != MAGIC_BYTES * NUM_ITER * 2 || pkts != NUM_ITER * 2) {
 		error_cnt++;
-		test__printf("test_xdp_noinline:FAIL:stats %lld %lld\n",
-			     bytes, pkts);
+		printf("test_xdp_noinline:FAIL:stats %lld %lld\n",
+		       bytes, pkts);
 	}
 out:
 	bpf_object__close(obj);

tools/testing/selftests/bpf/test_progs.c

@@ -40,14 +40,20 @@ static bool should_run(struct test_selector *sel, int num, const char *name)
 
 static void dump_test_log(const struct prog_test_def *test, bool failed)
 {
+	if (stdout == env.stdout)
+		return;
+
+	fflush(stdout); /* exports env.log_buf & env.log_cnt */
+
 	if (env.verbose || test->force_log || failed) {
 		if (env.log_cnt) {
-			fprintf(stdout, "%s", env.log_buf);
+			fprintf(env.stdout, "%s", env.log_buf);
 			if (env.log_buf[env.log_cnt - 1] != '\n')
-				fprintf(stdout, "\n");
+				fprintf(env.stdout, "\n");
 		}
 	}
-	env.log_cnt = 0;
+
+	fseeko(stdout, 0, SEEK_SET); /* rewind */
 }
 
 void test__end_subtest()
@@ -62,7 +68,7 @@ void test__end_subtest()
 
 	dump_test_log(test, sub_error_cnt);
 
-	printf("#%d/%d %s:%s\n",
+	fprintf(env.stdout, "#%d/%d %s:%s\n",
 	       test->test_num, test->subtest_num,
 	       test->subtest_name, sub_error_cnt ? "FAIL" : "OK");
 }
@@ -79,7 +85,8 @@ bool test__start_subtest(const char *name)
 	test->subtest_num++;
 
 	if (!name || !name[0]) {
-		fprintf(stderr, "Subtest #%d didn't provide sub-test name!\n",
+		fprintf(env.stderr,
+			"Subtest #%d didn't provide sub-test name!\n",
 			test->subtest_num);
 		return false;
 	}
@@ -98,66 +105,6 @@ void test__force_log() {
 	env.test->force_log = true;
 }
 
-void test__vprintf(const char *fmt, va_list args)
-{
-	size_t rem_sz;
-	int ret = 0;
-
-	if (env.verbose || (env.test && env.test->force_log)) {
-		vfprintf(stderr, fmt, args);
-		return;
-	}
-
-try_again:
-	rem_sz = env.log_cap - env.log_cnt;
-	if (rem_sz) {
-		va_list ap;
-
-		va_copy(ap, args);
-		/* we reserved extra byte for \0 at the end */
-		ret = vsnprintf(env.log_buf + env.log_cnt, rem_sz + 1, fmt, ap);
-		va_end(ap);
-
-		if (ret < 0) {
-			env.log_buf[env.log_cnt] = '\0';
-			fprintf(stderr, "failed to log w/ fmt '%s'\n", fmt);
-			return;
-		}
-	}
-
-	if (!rem_sz || ret > rem_sz) {
-		size_t new_sz = env.log_cap * 3 / 2;
-		char *new_buf;
-
-		if (new_sz < 4096)
-			new_sz = 4096;
-		if (new_sz < ret + env.log_cnt)
-			new_sz = ret + env.log_cnt;
-
-		/* +1 for guaranteed space for terminating \0 */
-		new_buf = realloc(env.log_buf, new_sz + 1);
-		if (!new_buf) {
-			fprintf(stderr, "failed to realloc log buffer: %d\n",
-				errno);
-			return;
-		}
-		env.log_buf = new_buf;
-		env.log_cap = new_sz;
-		goto try_again;
-	}
-
-	env.log_cnt += ret;
-}
-
-void test__printf(const char *fmt, ...)
-{
-	va_list args;
-
-	va_start(args, fmt);
-	test__vprintf(fmt, args);
-	va_end(args);
-}
-
 struct ipv4_packet pkt_v4 = {
 	.eth.h_proto = __bpf_constant_htons(ETH_P_IP),
 	.iph.ihl = 5,
@@ -331,7 +278,7 @@ enum ARG_KEYS {
 	ARG_VERIFIER_STATS = 's',
 	ARG_VERBOSE = 'v',
 };
-	
+
 static const struct argp_option opts[] = {
 	{ "num", ARG_TEST_NUM, "NUM", 0,
 	  "Run test number NUM only " },
@@ -349,7 +296,7 @@ static int libbpf_print_fn(enum libbpf_print_level level,
 {
 	if (!env.very_verbose && level == LIBBPF_DEBUG)
 		return 0;
-	test__vprintf(format, args);
+	vprintf(format, args);
 	return 0;
 }
 
@@ -477,6 +424,48 @@ static error_t parse_arg(int key, char *arg, struct argp_state *state)
 	return 0;
 }
 
+static void stdio_hijack(void)
+{
+#ifdef __GLIBC__
+	env.stdout = stdout;
+	env.stderr = stderr;
+
+	if (env.verbose) {
+		/* nothing to do, output to stdout by default */
+		return;
+	}
+
+	/* stdout and stderr -> buffer */
+	fflush(stdout);
+
+	stdout = open_memstream(&env.log_buf, &env.log_cnt);
+	if (!stdout) {
+		stdout = env.stdout;
+		perror("open_memstream");
+		return;
+	}
+
+	stderr = stdout;
+#endif
+}
+
+static void stdio_restore(void)
+{
+#ifdef __GLIBC__
+	if (stdout == env.stdout)
+		return;
+
+	fclose(stdout);
+	free(env.log_buf);
+
+	env.log_buf = NULL;
+	env.log_cnt = 0;
+
+	stdout = env.stdout;
+	stderr = env.stderr;
+#endif
+}
+
 int main(int argc, char **argv)
 {
 	static const struct argp argp = {
@@ -496,6 +485,7 @@ int main(int argc, char **argv)
 
 	env.jit_enabled = is_jit_enabled();
 
+	stdio_hijack();
 	for (i = 0; i < prog_test_cnt; i++) {
 		struct prog_test_def *test = &prog_test_defs[i];
 		int old_pass_cnt = pass_cnt;
@@ -523,13 +513,14 @@ int main(int argc, char **argv)
 
 		dump_test_log(test, test->error_cnt);
 
-		printf("#%d %s:%s\n", test->test_num, test->test_name,
-		       test->error_cnt ? "FAIL" : "OK");
+		fprintf(env.stdout, "#%d %s:%s\n",
+			test->test_num, test->test_name,
+			test->error_cnt ? "FAIL" : "OK");
 	}
+	stdio_restore();
 	printf("Summary: %d/%d PASSED, %d FAILED\n",
 	       env.succ_cnt, env.sub_succ_cnt, env.fail_cnt);
 
-	free(env.log_buf);
 	free(env.test_selector.num_set);
 	free(env.subtest_selector.num_set);
 

tools/testing/selftests/bpf/test_progs.h

@@ -56,9 +56,10 @@ struct test_env {
 	bool jit_enabled;
 
 	struct prog_test_def *test;
+	FILE *stdout;
+	FILE *stderr;
 	char *log_buf;
 	size_t log_cnt;
-	size_t log_cap;
 
 	int succ_cnt; /* successful tests */
 	int sub_succ_cnt; /* successful sub-tests */
@@ -69,8 +70,6 @@ extern int error_cnt;
 extern int pass_cnt;
 extern struct test_env env;
 
-extern void test__printf(const char *fmt, ...);
-extern void test__vprintf(const char *fmt, va_list args);
 extern void test__force_log();
 extern bool test__start_subtest(const char *name);
 
@@ -96,12 +95,12 @@ extern struct ipv6_packet pkt_v6;
 	int __ret = !!(condition);					\
 	if (__ret) {							\
 		error_cnt++;						\
-		test__printf("%s:FAIL:%s ", __func__, tag);		\
-		test__printf(format);					\
+		printf("%s:FAIL:%s ", __func__, tag);			\
+		printf(format);						\
 	} else {							\
 		pass_cnt++;						\
-		test__printf("%s:PASS:%s %d nsec\n",			\
-			      __func__, tag, duration);			\
+		printf("%s:PASS:%s %d nsec\n",				\
+		       __func__, tag, duration);			\
 	}								\
 	__ret;								\
 })