Re: Linux 5.6-rc1 kselftest build failures

[Aleksa Sarai]

On 2020-02-11, shuah <shuah@xxxxxxxxxx> wrote:
> openat2:
> 
> tools/testing/selftests/openat2'
> gcc -Wall -O2 -g -fsanitize=address -fsanitize=undefined openat2_test.c
> helpers.c  -o tools/testing/selftests/openat2/openat2_test
> In file included from /usr/include/fcntl.h:301,
>                  from helpers.c:9:
> In function âopenatâ,
>     inlined from âtouchatâ at helpers.c:49:11:
> /usr/include/x86_64-linux-gnu/bits/fcntl2.h:126:4: error: call to
> â__openat_missing_modeâ declared with attribute error: openat with O_CREAT
> or O_TMPFILE in third argument needs 4 arguments
>   126 |    __openat_missing_mode ();
>       |    ^~~~~~~~~~~~~~~~~~~~~~~~

Yeah, that's a brain-o -- it looks like you have a newer glibc than
me which gives you a warning when you don't set the mode. The fix should
be just the following:

--8<-----------------------------------------------------------------------
Subject: [PATCH] selftests: openat2: fix build error on newer glibc

It appears that newer glibcs check that openat(O_CREAT) was provided a
fourth argument (rather than passing garbage), resulting in the
following build error:

  In file included from /usr/include/fcntl.h:301,
                   from helpers.c:9:
  In function âopenatâ,
      inlined from âtouchatâ at helpers.c:49:11:
  /usr/include/x86_64-linux-gnu/bits/fcntl2.h:126:4: error: call to
  â__openat_missing_modeâ declared with attribute error: openat with O_CREAT
  or O_TMPFILE in third argument needs 4 arguments
    126 |    __openat_missing_mode ();
        |    ^~~~~~~~~~~~~~~~~~~~~~~~

Reported-by: Shuah Khan <shuah@xxxxxxxxxx>
Signed-off-by: Aleksa Sarai <cyphar@xxxxxxxxxx>
---
 tools/testing/selftests/openat2/helpers.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/openat2/helpers.c b/tools/testing/selftests/openat2/helpers.c
index e9a6557ab16f..5074681ffdc9 100644
--- a/tools/testing/selftests/openat2/helpers.c
+++ b/tools/testing/selftests/openat2/helpers.c
@@ -46,7 +46,7 @@ int sys_renameat2(int olddirfd, const char *oldpath,
 
 int touchat(int dfd, const char *path)
 {
-	int fd = openat(dfd, path, O_CREAT);
+	int fd = openat(dfd, path, O_CREAT, 0700);
 	if (fd >= 0)
 		close(fd);
 	return fd;
-- 
2.25.0

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