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[v4,14/18] selftests/nolibc: vfprintf: remove MEMFD_CREATE dependency

Message ID 94bdca8d8610e85bb1683bf10a5005ca92c3cb57.1688750763.git.falcon@tinylab.org
State Accepted
Commit 6861b1a3398ec3f1b830d7d190a6ffbc3be8ab6b
Headers show
Series selftests/nolibc: allow run with minimal kernel config | expand

Commit Message

Zhangjin Wu July 7, 2023, 6:40 p.m. UTC
The vfprintf test case require to open a temporary file to write, the
old memfd_create() method is perfect but has strong dependency on
MEMFD_CREATE and also TMPFS or HUGETLBFS (see fs/Kconfig):

    config MEMFD_CREATE
	def_bool TMPFS || HUGETLBFS

And from v6.2, MFD_NOEXEC_SEAL must be passed for the non-executable
memfd, otherwise, The kernel warning will be output to the test result
like this:

        Running test 'vfprintf'
        0 emptymemfd_create() without MFD_EXEC nor MFD_NOEXEC_SEAL, pid=1 'init'
         "" = ""                                                  [OK]

To avoid such warning and also to remove the MEMFD_CREATE dependency,
let's open a file from tmpfs directly.

The /tmp directory is used to detect the existing of tmpfs, if not
there, skip instead of fail.

And further, for pid == 1, the initramfs is loaded as ramfs, which can
be used as tmpfs, so, it is able to further remove TMPFS dependency too.

Suggested-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/lkml/9ad51430-b7c0-47dc-80af-20c86539498d@t-8ch.de
Reviewed-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
---
 tools/testing/selftests/nolibc/nolibc-test.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
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Patch

diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 6b863f7b677c..494195890e4b 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -875,10 +875,10 @@  static int expect_vfprintf(int llen, size_t c, const char *expected, const char
 	FILE *memfile;
 	va_list args;
 
-	fd = memfd_create("vfprintf", 0);
+	fd = open("/tmp", O_TMPFILE | O_EXCL | O_RDWR, 0600);
 	if (fd == -1) {
-		pad_spc(llen, 64, "[FAIL]\n");
-		return 1;
+		pad_spc(llen, 64, "[SKIPPED]\n");
+		return 0;
 	}
 
 	memfile = fdopen(fd, "w+");