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[thirdparty/glibc.git] / sysdeps / unix / sysv / linux / microblaze / pselect.c

/* Synchronous I/O multiplexing.  Linux/microblaze version.
   Copyright (C) 2019-2020 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 <errno.h>
#include <signal.h>
#include <time.h>
#include <sys/poll.h>
#include <sysdep-cancel.h>

#ifndef __ASSUME_PSELECT
# define __pselect __pselect_syscall
#endif

/* If pselect is supported, just use the Linux generic implementation.  */
#include <sysdeps/unix/sysv/linux/pselect.c>

#ifndef __ASSUME_PSELECT
# undef __pselect
int
__pselect (int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
	   const struct timespec *timeout, const sigset_t *sigmask)
{
  int ret = __pselect_syscall (nfds, readfds, writefds, exceptfds, timeout,
			       sigmask);
  if (ret >= 0 || errno != ENOSYS)
    return ret;

  /* The fallback uses 'select' which shows the race condition regarding
     signal mask set/restore, requires two additional syscalls, and has
     a worse timeout precision (microseconds instead of nanoseconds).  */

  struct timeval tval, *ptval = NULL;
  if (timeout != NULL)
    {
      if (! valid_nanoseconds (timeout->tv_nsec))
	{
	  __set_errno (EINVAL);
	  return -1;
	}

      TIMESPEC_TO_TIMEVAL (&tval, timeout);
      ptval = &tval;
    }

  sigset_t savemask;
  if (sigmask != NULL)
    __sigprocmask (SIG_SETMASK, sigmask, &savemask);

  /* select itself is a cancellation entrypoint.  */
  ret = __select (nfds, readfds, writefds, exceptfds, ptval);

  if (sigmask != NULL)
    __sigprocmask (SIG_SETMASK, &savemask, NULL);

  return ret;
}
weak_alias (__pselect, pselect)
#endif