1  /* Copyright (C) 2006-2023 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