io/ppoll.c

   1 /* Copyright (C) 2006-2020 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2006.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <limits.h>
  21 #include <signal.h>
  22 #include <stddef.h>     /* For NULL.  */
  23 #include <sys/poll.h>
  24 #include <sysdep-cancel.h>
  25 #include <time.h>
  26
  27
  28 int
  29 ppoll (struct pollfd *fds, nfds_t nfds, const struct timespec *timeout,
  30        const sigset_t *sigmask)
  31 {
  32   int tval = -1;
  33
  34   /* poll uses a simple millisecond value.  Convert it.  */
  35   if (timeout != NULL)
  36     {
  37       if (timeout->tv_sec < 0 || ! valid_nanoseconds (timeout->tv_nsec))
  38         {
  39           __set_errno (EINVAL);
  40           return -1;
  41         }
  42
  43       if (timeout->tv_sec > INT_MAX / 1000
  44           || (timeout->tv_sec == INT_MAX / 1000
  45               && ((timeout->tv_nsec + 999999) / 1000000 > INT_MAX % 1000)))
  46         /* We cannot represent the timeout in an int value.  Wait
  47            forever.  */
  48         tval = -1;
  49       else
  50         tval = (timeout->tv_sec * 1000
  51                 + (timeout->tv_nsec + 999999) / 1000000);
  52     }
  53
  54   /* The setting and restoring of the signal mask and the select call
  55      should be an atomic operation.  This can't be done without kernel
  56      help.  */
  57   sigset_t savemask;
  58   if (sigmask != NULL)
  59     __sigprocmask (SIG_SETMASK, sigmask, &savemask);
  60
  61   /* Note the ppoll() is a cancellation point.  But since we call
  62      poll() which itself is a cancellation point we do not have
  63      to do anything here.  */
  64   int retval = __poll (fds, nfds, tval);
  65
  66   if (sigmask != NULL)
  67     __sigprocmask (SIG_SETMASK, &savemask, NULL);
  68
  69   return retval;
  70 }
  71
  72 #ifndef ppoll
  73 libc_hidden_def (ppoll);
  74 #endif