Dear Community,

> This change adds new test to assess select()'s timeout related
> functionality (the rdfs set provides valid fd - stderr - but during
> normal program operation there is no data to be read, so one just
> waits for timeout).
> 
> To be more specific - two use cases are checked:
> - if select() times out immediately when passed struct timeval has
>   zero values of tv_usec and tv_sec.
> - if select() times out after timeout specified in passed argument

Do you have any comments regarding this patch?

> ---
>  misc/Makefile     |  2 +-
>  misc/tst-select.c | 70
> +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 71
> insertions(+), 1 deletion(-) create mode 100644 misc/tst-select.c
> 
> diff --git a/misc/Makefile b/misc/Makefile
> index a8363d4b76..a3545f047e 100644
> --- a/misc/Makefile
> +++ b/misc/Makefile
> @@ -88,7 +88,7 @@ tests := tst-dirname tst-tsearch tst-fdset
> tst-mntent tst-hsearch \ tst-preadvwritev tst-preadvwritev64
> tst-makedev tst-empty \ tst-preadvwritev2 tst-preadvwritev64v2
> tst-warn-wide \ tst-ldbl-warn tst-ldbl-error tst-dbl-efgcvt
> tst-ldbl-efgcvt \
> -	 tst-mntent-autofs tst-syscalls tst-mntent-escape
> +	 tst-mntent-autofs tst-syscalls tst-mntent-escape tst-select
>  
>  tests-time64 := tst-pselect-time64
>  
> diff --git a/misc/tst-select.c b/misc/tst-select.c
> new file mode 100644
> index 0000000000..ea776c8880
> --- /dev/null
> +++ b/misc/tst-select.c
> @@ -0,0 +1,70 @@
> +/* Test for select timeout
> +   Copyright (C) 2021 Free Software Foundation, Inc.
> +   This file is part of the GNU C Library.
> +
> +   The GNU C Library is free software; you can redistribute it and/or
> +   modify it under the terms of the GNU Lesser General Public
> +   License as published by the Free Software Foundation; either
> +   version 2.1 of the License, or (at your option) any later version.
> +
> +   The GNU C Library is distributed in the hope that it will be
> useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> +   Lesser General Public License for more details.
> +
> +   You should have received a copy of the GNU Lesser General Public
> +   License along with the GNU C Library; if not, see
> +   <https://www.gnu.org/licenses/>.  */
> +
> +#include <time.h>
> +#include <errno.h>
> +#include <stdbool.h>
> +#include <sys/select.h>
> +#include <support/check.h>
> +#include <support/xtime.h>
> +#include <support/timespec.h>
> +
> +#define TST_SELECT_TIMEOUT 1
> +#define TST_SELECT_FD_ERR 2
> +
> +static int test_select_timeout (bool zero_tmo)
> +{
> +  const int fds = TST_SELECT_FD_ERR;
> +  int timeout = TST_SELECT_TIMEOUT;
> +  struct timeval to = { 0, 0 };
> +  struct timespec ts;
> +  fd_set rfds;
> +
> +  FD_ZERO (&rfds);
> +  FD_SET (fds, &rfds);
> +
> +  if (zero_tmo)
> +    timeout = 0;
> +
> +  to.tv_sec = timeout;
> +  ts = xclock_now (CLOCK_REALTIME);
> +  ts = timespec_add (ts, (struct timespec) { timeout, 0 });
> +
> +  /* Wait for timeout.  */
> +  int ret = select (fds + 1, &rfds, NULL, NULL, &to);
> +  if (ret == -1)
> +    FAIL_EXIT1 ("select failed: %m\n");
> +
> +  TEST_TIMESPEC_NOW_OR_AFTER (CLOCK_REALTIME, ts);
> +
> +  return 0;
> +}
> +
> +static int
> +do_test (void)
> +{
> +  /* Check if select exits immediately.  */
> +  test_select_timeout (true);
> +
> +  /* Check if select exits after specified timeout.  */
> +  test_select_timeout (false);
> +
> +  return 0;
> +}
> +
> +#include <support/test-driver.c>




Best regards,

Lukasz Majewski

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