[RFC PATCH 5/6] selftests/liveupdate: Add API to preserve a batch of FDs

[Samiullah Khawaja <skhawaja@google.com>]

Add luo_session_preserve_fds() that can be used to preserve a batch of
FDs using the LIVEUPDATE_SESSION_PRESERVE_FDS ioctl.

Signed-off-by: Samiullah Khawaja <skhawaja@google.com>
---
 .../liveupdate/lib/include/libliveupdate.h    |  2 ++
 .../selftests/liveupdate/lib/lu_utils.c       | 20 +++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/tools/testing/selftests/liveupdate/lib/include/libliveupdate.h b/tools/testing/selftests/liveupdate/lib/include/libliveupdate.h
index fa07fed08364..9aaf6f28ef56 100644
--- a/tools/testing/selftests/liveupdate/lib/include/libliveupdate.h
+++ b/tools/testing/selftests/liveupdate/lib/include/libliveupdate.h
@@ -29,6 +29,8 @@ int luo_get_session_name(int session_fd, char *name, size_t name_len);
 
 int luo_ensure_nofile_limit(long min_limit);
 int luo_session_preserve_fd(int session_fd, int fd, __u64 token);
+int luo_session_preserve_fds(int session_fd, const int *fds,
+			     const __u64 *tokens, __u32 nr, __u32 *failed_idx);
 int luo_session_retrieve_fd(int session_fd, __u64 token);
 
 int create_and_preserve_memfd(int session_fd, int token, const char *data);
diff --git a/tools/testing/selftests/liveupdate/lib/lu_utils.c b/tools/testing/selftests/liveupdate/lib/lu_utils.c
index 74d41115c281..1290f27ff004 100644
--- a/tools/testing/selftests/liveupdate/lib/lu_utils.c
+++ b/tools/testing/selftests/liveupdate/lib/lu_utils.c
@@ -93,6 +93,26 @@ int luo_session_preserve_fd(int session_fd, int fd, __u64 token)
 	return 0;
 }
 
+int luo_session_preserve_fds(int session_fd, const int *fds,
+			     const __u64 *tokens, __u32 nr, __u32 *failed_idx)
+{
+	struct liveupdate_session_preserve_fds arg = {
+		.size = sizeof(arg),
+		.nr = nr,
+		.fds = (__u64)(uintptr_t)fds,
+		.tokens = (__u64)(uintptr_t)tokens,
+	};
+	int ret = 0;
+
+	if (ioctl(session_fd, LIVEUPDATE_SESSION_PRESERVE_FDS, &arg))
+		ret = -errno;
+
+	if (failed_idx)
+		*failed_idx = arg.out_failed_index;
+
+	return ret;
+}
+
 int luo_session_retrieve_fd(int session_fd, __u64 token)
 {
 	struct liveupdate_session_retrieve_fd arg = {
-- 
2.56.0.rc1.315.gc6ed9934b7-goog