[PATCH v3 bpf-next 18/19] selftests/bpf: add testing of log_buf==NULL condition for BPF_PROG_LOAD

[Andrii Nakryiko <andrii@xxxxxxxxxx>]

Add few extra test conditions to validate that it's ok to pass
log_buf==NULL and log_size==0 to BPF_PROG_LOAD command with the intent
to get log_size_actual without providing a buffer.

Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
 .../selftests/bpf/prog_tests/verifier_log.c   | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/verifier_log.c b/tools/testing/selftests/bpf/prog_tests/verifier_log.c
index 410bab151f1b..e22a4a4c9f1d 100644
--- a/tools/testing/selftests/bpf/prog_tests/verifier_log.c
+++ b/tools/testing/selftests/bpf/prog_tests/verifier_log.c
@@ -163,26 +163,49 @@ static void verif_log_subtest(const char *name, bool expect_load_error, int log_
 	opts.log_buf = logs.buf;
 	opts.log_level = log_level | 8; /* BPF_LOG_FIXED */
 	opts.log_size = sizeof(logs.buf);
+	opts.log_size_actual = 0;
 	res = load_prog(&opts, expect_load_error);
 	ASSERT_NEQ(res, -ENOSPC, "prog_load_res_fixed");
 
 	log_sz_actual_fixed = opts.log_size_actual;
 	ASSERT_GT(log_sz_actual_fixed, 0, "log_sz_actual_fixed");
 
+	/* (FIXED, NULL) get actual log size */
+	opts.log_buf = NULL;
+	opts.log_level = log_level | 8; /* BPF_LOG_FIXED */
+	opts.log_size = 0;
+	opts.log_size_actual = 0;
+	res = load_prog(&opts, true /* should fail */);
+	ASSERT_EQ(res, -ENOSPC, "prog_load_res_fixed_null");
+	ASSERT_EQ(opts.log_size_actual, log_sz_actual_fixed, "log_sz_fixed_null_eq");
+	printf("FIXED ACTUAL %u\n", opts.log_size_actual);
+
 	/* (ROLLING) get actual log size */
 	opts.log_buf = logs.buf;
 	opts.log_level = log_level;
 	opts.log_size = sizeof(logs.buf);
+	opts.log_size_actual = 0;
 	res = load_prog(&opts, expect_load_error);
 	ASSERT_NEQ(res, -ENOSPC, "prog_load_res_rolling");
 
 	log_sz_actual_rolling = opts.log_size_actual;
 	ASSERT_EQ(log_sz_actual_rolling, log_sz_actual_fixed, "log_sz_actual_eq");
 
+	/* (ROLLING, NULL) get actual log size */
+	opts.log_buf = NULL;
+	opts.log_level = log_level;
+	opts.log_size = 0;
+	opts.log_size_actual = 0;
+	res = load_prog(&opts, true /* should fail */);
+	ASSERT_EQ(res, -ENOSPC, "prog_load_res_rolling_null");
+	ASSERT_EQ(opts.log_size_actual, log_sz_actual_rolling, "log_sz_actual_null_eq");
+	printf("ROLLING ACTUAL %u\n", opts.log_size_actual);
+
 	/* (FIXED) expect -ENOSPC for one byte short log */
 	opts.log_buf = logs.buf;
 	opts.log_level = log_level | 8; /* BPF_LOG_FIXED */
 	opts.log_size = log_sz_actual_fixed - 1;
+	opts.log_size_actual = 0;
 	res = load_prog(&opts, true /* should fail */);
 	ASSERT_EQ(res, -ENOSPC, "prog_load_res_too_short_fixed");
 
@@ -190,6 +213,7 @@ static void verif_log_subtest(const char *name, bool expect_load_error, int log_
 	opts.log_buf = logs.buf;
 	opts.log_level = log_level | 8; /* BPF_LOG_FIXED */
 	opts.log_size = log_sz_actual_fixed;
+	opts.log_size_actual = 0;
 	res = load_prog(&opts, expect_load_error);
 	ASSERT_NEQ(res, -ENOSPC, "prog_load_res_just_right_fixed");
 
@@ -204,6 +228,7 @@ static void verif_log_subtest(const char *name, bool expect_load_error, int log_
 	opts.log_buf = logs.buf;
 	opts.log_level = log_level;
 	opts.log_size = log_sz_actual_rolling;
+	opts.log_size_actual = 0;
 	res = load_prog(&opts, expect_load_error);
 	ASSERT_NEQ(res, -ENOSPC, "prog_load_res_just_right_rolling");
 
-- 
2.34.1