sysdeps/unix/sysv/linux/poll.c

   1 /* Poll system call, with emulation if it is not available.
   2    Copyright (C) 1997, 1998, 1999, 2000 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <errno.h>
  21 #include <sys/poll.h>
  22
  23 #include <sysdep.h>
  24 #include <sys/syscall.h>
  25
  26 #include "kernel-features.h"
  27
  28 #if defined __NR_poll || __ASSUME_POLL_SYSCALL > 0
  29
  30 extern int __syscall_poll (struct pollfd *fds, unsigned int nfds,
  31                            int timeout);
  32
  33 # if __ASSUME_POLL_SYSCALL == 0
  34 static int __emulate_poll (struct pollfd *fds, unsigned long int nfds,
  35                            int timeout) internal_function;
  36 # endif
  37
  38 /* The real implementation.  */
  39 int
  40 __poll (fds, nfds, timeout)
  41      struct pollfd *fds;
  42      unsigned long int nfds;
  43      int timeout;
  44 {
  45 # if __ASSUME_POLL_SYSCALL == 0
  46   static int must_emulate;
  47
  48   if (!must_emulate)
  49     {
  50       int errno_saved = errno;
  51       int retval = INLINE_SYSCALL (poll, 3, fds, nfds, timeout);
  52
  53       if (retval >= 0 || errno != ENOSYS)
  54         return retval;
  55
  56       __set_errno (errno_saved);
  57       must_emulate = 1;
  58     }
  59
  60   return __emulate_poll (fds, nfds, timeout);
  61 # else
  62   return INLINE_SYSCALL (poll, 3, fds, nfds, timeout);
  63 # endif
  64 }
  65 weak_alias (__poll, poll)
  66
  67 /* Get the emulation code.  */
  68 # define __poll(fds, nfds, timeout) \
  69   static internal_function __emulate_poll (fds, nfds, timeout)
  70 #endif
  71
  72 #if __ASSUME_POLL_SYSCALL == 0
  73 # include <sysdeps/unix/bsd/poll.c>
  74 #endif