[PATCH v1 3/7] selftest/landlock: Make tests build with old libc

["Mickaël Salaün" <mic@digikod.net>]

From: Mickaël Salaün <mic@linux.microsoft.com>

Replace SYS_<syscall> with __NR_<syscall>.  Using the __NR_<syscall>
notation, provided by UAPI, is useful to build tests on systems without
the SYS_<syscall> definitions.

Replace SYS_pivot_root with __NR_pivot_root, and SYS_move_mount with
__NR_move_mount.

Define renameat2() and RENAME_EXCHANGE if they are unknown to old build
systems.

Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Link: https://lore.kernel.org/r/20220221155311.166278-4-mic@digikod.net
---
 tools/testing/selftests/landlock/fs_test.c | 23 +++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 10c9a1e4ebd9..699cda25a12a 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -22,6 +22,19 @@
 
 #include "common.h"
 
+#ifndef renameat2
+int renameat2(int olddirfd, const char *oldpath, int newdirfd,
+		const char *newpath, unsigned int flags)
+{
+	return syscall(__NR_renameat2, olddirfd, oldpath, newdirfd, newpath,
+			flags);
+}
+#endif
+
+#ifndef RENAME_EXCHANGE
+#define RENAME_EXCHANGE		(1 << 1)
+#endif
+
 #define TMP_DIR		"tmp"
 #define BINARY_PATH	"./true"
 
@@ -1249,7 +1262,7 @@ TEST_F_FORK(layout1, rule_inside_mount_ns)
 	int ruleset_fd;
 
 	set_cap(_metadata, CAP_SYS_ADMIN);
-	ASSERT_EQ(0, syscall(SYS_pivot_root, dir_s3d2, dir_s3d3)) {
+	ASSERT_EQ(0, syscall(__NR_pivot_root, dir_s3d2, dir_s3d3)) {
 		TH_LOG("Failed to pivot root: %s", strerror(errno));
 	};
 	ASSERT_EQ(0, chdir("/"));
@@ -1282,7 +1295,7 @@ TEST_F_FORK(layout1, mount_and_pivot)
 	set_cap(_metadata, CAP_SYS_ADMIN);
 	ASSERT_EQ(-1, mount(NULL, dir_s3d2, NULL, MS_RDONLY, NULL));
 	ASSERT_EQ(EPERM, errno);
-	ASSERT_EQ(-1, syscall(SYS_pivot_root, dir_s3d2, dir_s3d3));
+	ASSERT_EQ(-1, syscall(__NR_pivot_root, dir_s3d2, dir_s3d3));
 	ASSERT_EQ(EPERM, errno);
 	clear_cap(_metadata, CAP_SYS_ADMIN);
 }
@@ -1301,12 +1314,12 @@ TEST_F_FORK(layout1, move_mount)
 	ASSERT_LE(0, ruleset_fd);
 
 	set_cap(_metadata, CAP_SYS_ADMIN);
-	ASSERT_EQ(0, syscall(SYS_move_mount, AT_FDCWD, dir_s3d2, AT_FDCWD,
+	ASSERT_EQ(0, syscall(__NR_move_mount, AT_FDCWD, dir_s3d2, AT_FDCWD,
 				dir_s1d2, 0)) {
 		TH_LOG("Failed to move mount: %s", strerror(errno));
 	}
 
-	ASSERT_EQ(0, syscall(SYS_move_mount, AT_FDCWD, dir_s1d2, AT_FDCWD,
+	ASSERT_EQ(0, syscall(__NR_move_mount, AT_FDCWD, dir_s1d2, AT_FDCWD,
 				dir_s3d2, 0));
 	clear_cap(_metadata, CAP_SYS_ADMIN);
 
@@ -1314,7 +1327,7 @@ TEST_F_FORK(layout1, move_mount)
 	ASSERT_EQ(0, close(ruleset_fd));
 
 	set_cap(_metadata, CAP_SYS_ADMIN);
-	ASSERT_EQ(-1, syscall(SYS_move_mount, AT_FDCWD, dir_s3d2, AT_FDCWD,
+	ASSERT_EQ(-1, syscall(__NR_move_mount, AT_FDCWD, dir_s3d2, AT_FDCWD,
 				dir_s1d2, 0));
 	ASSERT_EQ(EPERM, errno);
 	clear_cap(_metadata, CAP_SYS_ADMIN);
-- 
2.35.1