io/ppoll.c

   1 /* Copyright (C) 2006-2022 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <limits.h>
  20 #include <signal.h>
  21 #include <stddef.h>     /* For NULL.  */
  22 #include <sys/poll.h>
  23 #include <sysdep-cancel.h>
  24 #include <time.h>
  25
  26
  27 int
  28 ppoll (struct pollfd *fds, nfds_t nfds, const struct timespec *timeout,
  29        const sigset_t *sigmask)
  30 {
  31   int tval = -1;
  32
  33   /* poll uses a simple millisecond value.  Convert it.  */
  34   if (timeout != NULL)
  35     {
  36       if (timeout->tv_sec < 0 || ! valid_nanoseconds (timeout->tv_nsec))
  37         {
  38           __set_errno (EINVAL);
  39           return -1;
  40         }
  41
  42       if (timeout->tv_sec > INT_MAX / 1000
  43           || (timeout->tv_sec == INT_MAX / 1000
  44               && ((timeout->tv_nsec + 999999) / 1000000 > INT_MAX % 1000)))
  45         /* We cannot represent the timeout in an int value.  Wait
  46            forever.  */
  47         tval = -1;
  48       else
  49         tval = (timeout->tv_sec * 1000
  50                 + (timeout->tv_nsec + 999999) / 1000000);
  51     }
  52
  53   /* The setting and restoring of the signal mask and the select call
  54      should be an atomic operation.  This can't be done without kernel
  55      help.  */
  56   sigset_t savemask;
  57   if (sigmask != NULL)
  58     __sigprocmask (SIG_SETMASK, sigmask, &savemask);
  59
  60   /* Note the ppoll() is a cancellation point.  But since we call
  61      poll() which itself is a cancellation point we do not have
  62      to do anything here.  */
  63   int retval = __poll (fds, nfds, tval);
  64
  65   if (sigmask != NULL)
  66     __sigprocmask (SIG_SETMASK, &savemask, NULL);
  67
  68   return retval;
  69 }
  70
  71 #ifndef ppoll
  72 libc_hidden_def (ppoll);
  73 #endif