io/ppoll.c

   1 /* Copyright (C) 2006 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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <limits.h>
  22 #include <signal.h>
  23 #include <stddef.h>     /* For NULL.  */
  24 #include <sys/poll.h>
  25 #include <sysdep-cancel.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
  38           || timeout->tv_nsec < 0 || timeout->tv_nsec >= 1000000000)
  39         {
  40           __set_errno (EINVAL);
  41           return -1;
  42         }
  43
  44       if (timeout->tv_sec > INT_MAX / 1000
  45           || (timeout->tv_sec == INT_MAX / 1000
  46               && ((timeout->tv_nsec + 999999) / 1000000 > INT_MAX % 1000)))
  47         /* We cannot represent the timeout in an int value.  Wait
  48            forever.  */
  49         tval = -1;
  50       else
  51         tval = (timeout->tv_sec * 1000
  52                 + (timeout->tv_nsec + 999999) / 1000000);
  53     }
  54
  55   /* The setting and restoring of the signal mask and the select call
  56      should be an atomic operation.  This can't be done without kernel
  57      help.  */
  58   sigset_t savemask;
  59   if (sigmask != NULL)
  60     __sigprocmask (SIG_SETMASK, sigmask, &savemask);
  61
  62   /* Note the ppoll() is a cancellation point.  But since we call
  63      poll() which itself is a cancellation point we do not have
  64      to do anything here.  */
  65   int retval = __poll (fds, nfds, tval);
  66
  67   if (sigmask != NULL)
  68     __sigprocmask (SIG_SETMASK, &savemask, NULL);
  69
  70   return retval;
  71 }
  72
  73 #ifndef ppoll
  74 /* __poll handles cancellation.  */
  75 LIBC_CANCEL_HANDLED ();
  76 #endif