[PATCH bpf v2 2/2] selftests/bpf: assert link info uprobe_multi count & path_size if unset

[Tyrone Wu <wudevelops@gmail.com>]

Add assertions in `bpf_link_info.uprobe_multi` test to verify that
`count` and `path_size` fields are correctly populated when the fields
are unset.

This tests a previous bug where the `path_size` field was not populated
when `path` and `path_size` were unset.

Signed-off-by: Tyrone Wu <wudevelops@gmail.com>
---
V1 -> V2:
- Verify bpf_link_get_info_by_fd was successful before continuing with test

 tools/testing/selftests/bpf/prog_tests/fill_link_info.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
index 745c5ada4c4b..d50cbd8040d4 100644
--- a/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
+++ b/tools/testing/selftests/bpf/prog_tests/fill_link_info.c
@@ -420,6 +420,15 @@ verify_umulti_link_info(int fd, bool retprobe, __u64 *offsets,
 	if (!ASSERT_NEQ(err, -1, "readlink"))
 		return -1;
 
+	memset(&info, 0, sizeof(info));
+	err = bpf_link_get_info_by_fd(fd, &info, &len);
+	if (!ASSERT_OK(err, "bpf_link_get_info_by_fd"))
+		return -1;
+
+	ASSERT_EQ(info.uprobe_multi.count, 3, "info.uprobe_multi.count");
+	ASSERT_EQ(info.uprobe_multi.path_size, strlen(path) + 1,
+		  "info.uprobe_multi.path_size");
+
 	for (bit = 0; bit < 8; bit++) {
 		memset(&info, 0, sizeof(info));
 		info.uprobe_multi.path = ptr_to_u64(path_buf);
-- 
2.43.0