Several test_progs tests already capture libbpf log in order to check
for some expected output, e.g bpf_tcp_ca.c, kfunc_dynptr_param.c,
log_buf.c and a few others.
This commit provides a, hopefully, simple API to capture libbpf log
w/o necessity to define new print callback in each test:
/* Creates a global memstream capturing all output passed to
* libbpf_print_fn.
* Returns 0 on success, negative value on failure.
* On failure the description is printed using PRINT_FAIL and
* current test case is marked as fail.
*/
int start_libbpf_log_capture(void)
/* Destroys global memstream created by start_libbpf_log_capture().
* Returns a pointer to captured data which has to be freed.
* Returned buffer is null terminated.
*/
char *stop_libbpf_log_capture(void)
The intended usage is as follows:
if (start_libbpf_log_capture())
return;
use_libbpf();
char *log = stop_libbpf_log_capture();
ASSERT_HAS_SUBSTR(log, "... expected ...", "expected some message");
free(log);
As a safety measure, free(start_libbpf_log_capture()) is invoked in the
epilogue of the test_progs.c:run_one_test().
Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
---
tools/testing/selftests/bpf/test_progs.c | 57 ++++++++++++++++++++++++
tools/testing/selftests/bpf/test_progs.h | 3 ++
2 files changed, 60 insertions(+)
diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index 808550986f30..698c7387b310 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -683,9 +683,65 @@ static const struct argp_option opts[] = {
{},
};
+static FILE *libbpf_capture_stream;
+
+static struct {
+ char *buf;
+ size_t buf_sz;
+} libbpf_output_capture;
+
+/* Creates a global memstream capturing all output passed to libbpf_print_fn.
+ * Returns 0 on success, negative value on failure.
+ * On failure the description is printed using PRINT_FAIL and
+ * current test case is marked as fail.
+ */
+int start_libbpf_log_capture(void)
+{
+ if (libbpf_capture_stream) {
+ PRINT_FAIL("%s: libbpf_capture_stream != NULL\n", __func__);
+ return -EINVAL;
+ }
+
+ libbpf_capture_stream = open_memstream(&libbpf_output_capture.buf,
+ &libbpf_output_capture.buf_sz);
+ if (!libbpf_capture_stream) {
+ PRINT_FAIL("%s: open_memstream failed errno=%d\n", __func__, errno);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+/* Destroys global memstream created by start_libbpf_log_capture().
+ * Returns a pointer to captured data which has to be freed.
+ * Returned buffer is null terminated.
+ */
+char *stop_libbpf_log_capture(void)
+{
+ char *buf;
+
+ if (!libbpf_capture_stream)
+ return NULL;
+
+ fputc(0, libbpf_capture_stream);
+ fclose(libbpf_capture_stream);
+ libbpf_capture_stream = NULL;
+ /* get 'buf' after fclose(), see open_memstream() documentation */
+ buf = libbpf_output_capture.buf;
+ bzero(&libbpf_output_capture, sizeof(libbpf_output_capture));
+ return buf;
+}
+
static int libbpf_print_fn(enum libbpf_print_level level,
const char *format, va_list args)
{
+ if (libbpf_capture_stream) {
+ va_list args2;
+
+ va_copy(args2, args);
+ vfprintf(libbpf_capture_stream, format, args2);
+ }
+
if (env.verbosity < VERBOSE_VERY && level == LIBBPF_DEBUG)
return 0;
vfprintf(stdout, format, args);
@@ -1081,6 +1137,7 @@ static void run_one_test(int test_num)
cleanup_cgroup_environment();
stdio_restore();
+ free(stop_libbpf_log_capture());
dump_test_log(test, state, false, false, NULL);
}
diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
index 80df51244886..0ba5a20b19ba 100644
--- a/tools/testing/selftests/bpf/test_progs.h
+++ b/tools/testing/selftests/bpf/test_progs.h
@@ -397,6 +397,9 @@ int test__join_cgroup(const char *path);
system(cmd); \
})
+int start_libbpf_log_capture(void);
+char *stop_libbpf_log_capture(void);
+
static inline __u64 ptr_to_u64(const void *ptr)
{
return (__u64) (unsigned long) ptr;
--
2.43.0
