Re: [LTP] [PATCH v2 1/2] openat2: define _GNU_SOURCE and include <fcntl.h>

[Petr Vorel <pvorel@suse.cz>]

hi Li,

> On Fedora Rawhide (glibc 2.43+), libc exposes openat2() and struct open_how,
> so our configure script defines HAVE_OPENAT2 and the fallback definition in
> lapi/openat2.h gets skipped. But openat20*.c never included <fcntl.h> (and
> lacked _GNU_SOURCE), so the libc-provided prototype and struct stayed hidden,
> so compilation failed:

>   # uname -r
>   6.18.0-65.fc44.x86_64

>   # rpm -qf /usr/include/fcntl.h
>   glibc-devel-2.43-1.fc44.x86_64

>   # nm -D /usr/lib64/libc.so.6 | grep -w openat2
>   00000000000eb890 W openat2@@GLIBC_2.43

>   # make -C testcase/kernel/syscalls/openat2
>   openat201.c:27:62: error: invalid application of ‘sizeof’ to incomplete type ‘struct open_how’
>     27 |         {&dir_fd, TEST_FILE, O_RDWR, S_IRWXU, 0, &how, sizeof(*how)},

> Define _GNU_SOURCE and include <fcntl.h> in openat2 tests to make the
> prototype available and fix the build.

> Signed-off-by: Li Wang <liwang@redhat.com>
> ---
>  testcases/kernel/syscalls/openat2/openat201.c | 3 +++
>  testcases/kernel/syscalls/openat2/openat202.c | 3 +++
>  testcases/kernel/syscalls/openat2/openat203.c | 3 +++
>  3 files changed, 9 insertions(+)

> diff --git a/testcases/kernel/syscalls/openat2/openat201.c b/testcases/kernel/syscalls/openat2/openat201.c
> index ecd63b150..40ac2f6d9 100644
> --- a/testcases/kernel/syscalls/openat2/openat201.c
> +++ b/testcases/kernel/syscalls/openat2/openat201.c
> @@ -4,6 +4,9 @@
>   *
>   * Basic openat2() test.
>   */
> +#define _GNU_SOURCE

Why _GNU_SOURCE? glibc test tst-openat2.c [1] which includes <fcntl.h>, uses
struct open_how and test openat2() does not define it. Neither openat2() nor
struct open_how are guarded by #ifdef __USE_GNU.

O_DIRECTORY is guarded by #ifdef __USE_XOPEN2K8 but this should be safe as we
compile with -std=gnu99.

I mean it's not a big deal, but if it works without it please remove it.

[1] https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/tst-openat2.c
[2] https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/bits/openat2.h

> +#include <fcntl.h>

Should not we use include lapi/fcntl.h?

> +
>  #include "tst_test.h"
>  #include "lapi/openat2.h"

lapi/openat2.h uses struct open_how directly, shouldn't be included lapi/fcntl.h
there?

Kind regards,
Petr

> diff --git a/testcases/kernel/syscalls/openat2/openat202.c b/testcases/kernel/syscalls/openat2/openat202.c
> index 6d1b5a67c..329c6a4a5 100644
> --- a/testcases/kernel/syscalls/openat2/openat202.c
> +++ b/testcases/kernel/syscalls/openat2/openat202.c
> @@ -4,6 +4,9 @@
>   *
>   * openat2() tests with various resolve flags.
>   */
> +#define _GNU_SOURCE
> +#include <fcntl.h>
> +
>  #include "tst_test.h"
>  #include "lapi/openat2.h"

> diff --git a/testcases/kernel/syscalls/openat2/openat203.c b/testcases/kernel/syscalls/openat2/openat203.c
> index 6ac49ef4c..cd0c00d75 100644
> --- a/testcases/kernel/syscalls/openat2/openat203.c
> +++ b/testcases/kernel/syscalls/openat2/openat203.c
> @@ -4,6 +4,9 @@
>   *
>   * Basic openat2() test to check various failures.
>   */
> +#define _GNU_SOURCE
> +#include <fcntl.h>
> +
>  #include "tst_test.h"
>  #include "lapi/openat2.h"

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