Re: [LTP] [PATCH v3] close: add test for double close EBADF

Petr Vorel
2026-04-13T20:45:56Z

Hi Jinseok,

> Verify that calling close() on an already closed file descriptor fails
> with EBADF.

> This test adds coverage for a common state transition case where a
> previously valid file descriptor becomes invalid after close().

> Signed-off-by: Jinseok Kim <always.starving0@gmail.com>
> ---
> Changes in v3:
> - Add O_RDWR flag to SAFE_OPEN
> - Link to v2: https://lore.kernel.org/ltp/20260411110405.7330-1-always.starving0@gmail.com
> Changes in v2:
> - Add additional test coverage to close02 instead of creating a separate
> close03 test.
> - Link to v1: https://lore.kernel.org/ltp/20260406133134.17238-2-always.starving0@gmail.com
> ---
> testcases/kernel/syscalls/close/close02.c | 42 ++++++++++++++++++++---
> 1 file changed, 38 insertions(+), 4 deletions(-)

> diff --git a/testcases/kernel/syscalls/close/close02.c b/testcases/kernel/syscalls/close/close02.c
> index 617c48237..3b3c61b1e 100644
> --- a/testcases/kernel/syscalls/close/close02.c
> +++ b/testcases/kernel/syscalls/close/close02.c
> @@ -5,17 +5,51 @@
> */

> /*\
> - * Call close(-1) and expects it to return EBADF.
> + * Verify :manpage:`close(2)` failure cases:
> + *
> + * 1) close(-1) returns EBADF.
> + * 2) closing the same fd twice returns EBADF on the second call.
> */

> #include <errno.h>
> +#include <fcntl.h>
> +
> #include "tst_test.h"

> -static void run(void)
> +enum case_type {
> + INVALID_FD,
> + DOUBLE_CLOSE,
> +};
> +
> +static struct tcase {
> + const char *desc;
> + enum case_type type;
> +} tcases[] = {
> + { "close(-1)", INVALID_FD },
> + { "close same fd twice", DOUBLE_CLOSE },
I'd slightly prefer to have fd and errnos here in the struct:
int fd;
int exp_errno;

Specially with other changes below. This way will follow more LTP errno test
approach and enum case_type will not be needed.

> +};
> +
> +static void verify_close(unsigned int i)
> {
> - TST_EXP_FAIL(close(-1), EBADF);
> + int fd;
> + struct tcase *tc = &tcases[i];
> +
> + switch (tc->type) {
> + case INVALID_FD:
> + TST_EXP_FAIL(close(-1), EBADF, "%s", tc->desc);
> + break;
> +
> + case DOUBLE_CLOSE:
> + fd = SAFE_OPEN("close02", O_CREAT | O_RDWR, 0600);
> +
> + TST_EXP_PASS(close(fd), "%s: first close()", tc->desc);
Thinking about it twice, I would move SAFE_OPEN() together with this line
converted to SAFE_CLOSE() to setup(). Why? We test errnos, therefore this is
really just a preparation.

Then, the runtime would really be
TST_EXP_PASS(close(tc->fd), "%s", tc->desc);

Kind regards,
Petr

> + TST_EXP_FAIL(close(fd), EBADF, "%s: second close()", tc->desc);
> + break;
> + }
> }

> static struct tst_test test = {
> - .test_all = run,
> + .needs_tmpdir = 1,
> + .tcnt = ARRAY_SIZE(tcases),
> + .test = verify_close,
> };