glibc/sysdeps/unix/sysv/linux/poll.c

/* Poll system call, with emulation if it is not available.
   Copyright (C) 1997, 1998 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 Library General Public License as
   published by the Free Software Foundation; either version 2 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <errno.h>
#include <sys/poll.h>

#include <sys/syscall.h>
#ifdef __NR_poll

extern int __syscall_poll __P ((struct pollfd *fds, unsigned int nfds,
				int timeout));
weak_extern (__syscall_poll)

static int __emulate_poll __P ((struct pollfd *fds, unsigned long int nfds,
				int timeout)) internal_function;

/* The real implementation.  */
int
poll (fds, nfds, timeout)
     struct pollfd *fds;
     unsigned long int nfds;
     int timeout;
{
  static int must_emulate = 0;
  int (*syscall) __P ((struct pollfd *, unsigned int, int)) = __syscall_poll;

  if (!must_emulate)
    {
      if (syscall)
	{
	  int errno_saved = errno;
	  int retval = __syscall_poll (fds, nfds, timeout);

	  if (retval >= 0 || errno != ENOSYS)
	    return retval;

	  __set_errno (errno_saved);
	}

      must_emulate = 1;
    }

  return __emulate_poll (fds, nfds, timeout);
}


/* Get the emulation code.  */
# define poll(fds, nfds, timeout) \
  static internal_function __emulate_poll (fds, nfds, timeout)
#endif
#include <sysdeps/unix/bsd/poll.c>