selftests/landlock: Add supports_filesystem() helper

Replace supports_overlayfs() with supports_filesystem() to be able to
check several filesystems.  This will be useful in a following commit.

Only check for overlay filesystem once in the setup step, and then rely
on self->skip_test.

Cc: Guenter Roeck <groeck@chromium.org>
Cc: Jeff Xu <jeffxu@google.com>
Link: https://lore.kernel.org/r/20230612191430.339153-4-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>

diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 0438651..c1e655f 100644 (file)
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -107,8 +107,10 @@ static bool fgrep(FILE *const inf, const char *const str)
        return false;
 }
 
-static bool supports_overlayfs(void)
+static bool supports_filesystem(const char *const filesystem)
 {
+       char str[32];
+       int len;
        bool res;
        FILE *const inf = fopen("/proc/filesystems", "r");
 
@@ -119,7 +121,12 @@ static bool supports_overlayfs(void)
        if (!inf)
                return true;
 
-       res = fgrep(inf, "nodev\toverlay\n");
+       len = snprintf(str, sizeof(str), "nodev\t%s\n", filesystem);
+       if (len >= sizeof(str))
+               /* Ignores too-long filesystem names. */
+               return true;
+
+       res = fgrep(inf, str);
        fclose(inf);
        return res;
 }
@@ -4044,14 +4051,17 @@ static const char (*merge_sub_files[])[] = {
  *         └── work
  */
 
-/* clang-format off */
-FIXTURE(layout2_overlay) {};
-/* clang-format on */
+FIXTURE(layout2_overlay)
+{
+       bool skip_test;
+};
 
 FIXTURE_SETUP(layout2_overlay)
 {
-       if (!supports_overlayfs())
-               SKIP(return, "overlayfs is not supported");
+       if (!supports_filesystem("overlay")) {
+               self->skip_test = true;
+               SKIP(return, "overlayfs is not supported (setup)");
+       }
 
        prepare_layout(_metadata);
 
@@ -4089,8 +4099,8 @@ FIXTURE_SETUP(layout2_overlay)
 
 FIXTURE_TEARDOWN(layout2_overlay)
 {
-       if (!supports_overlayfs())
-               SKIP(return, "overlayfs is not supported");
+       if (self->skip_test)
+               SKIP(return, "overlayfs is not supported (teardown)");
 
        EXPECT_EQ(0, remove_path(lower_do1_fl3));
        EXPECT_EQ(0, remove_path(lower_dl1_fl2));
@@ -4123,8 +4133,8 @@ FIXTURE_TEARDOWN(layout2_overlay)
 
 TEST_F_FORK(layout2_overlay, no_restriction)
 {
-       if (!supports_overlayfs())
-               SKIP(return, "overlayfs is not supported");
+       if (self->skip_test)
+               SKIP(return, "overlayfs is not supported (test)");
 
        ASSERT_EQ(0, test_open(lower_fl1, O_RDONLY));
        ASSERT_EQ(0, test_open(lower_dl1, O_RDONLY));
@@ -4289,8 +4299,8 @@ TEST_F_FORK(layout2_overlay, same_content_different_file)
        size_t i;
        const char *path_entry;
 
-       if (!supports_overlayfs())
-               SKIP(return, "overlayfs is not supported");
+       if (self->skip_test)
+               SKIP(return, "overlayfs is not supported (test)");
 
        /* Sets rules on base directories (i.e. outside overlay scope). */
        ruleset_fd = create_ruleset(_metadata, ACCESS_RW, layer1_base);