sysdeps/unix/sysv/linux/poll.c

   1 /* Poll system call, with emulation if it is not available.
   2    Copyright (C) 1997,1998,1999,2000,2001,2002 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 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 <sys/poll.h>
  22
  23 #include <sysdep.h>
  24 #include <sys/syscall.h>
  25 #include <bp-checks.h>
  26
  27 #include "kernel-features.h"
  28
  29 #if defined __NR_poll || __ASSUME_POLL_SYSCALL > 0
  30
  31 extern int __syscall_poll (struct pollfd *__unbounded fds,
  32                            unsigned int nfds, int timeout);
  33
  34 # if __ASSUME_POLL_SYSCALL == 0
  35 static int __emulate_poll (struct pollfd *fds, nfds_t nfds,
  36                            int timeout) internal_function;
  37 # endif
  38
  39 /* The real implementation.  */
  40 int
  41 __poll (fds, nfds, timeout)
  42      struct pollfd *fds;
  43      nfds_t nfds;
  44      int timeout;
  45 {
  46 # if __ASSUME_POLL_SYSCALL == 0
  47   static int must_emulate;
  48
  49   if (!must_emulate)
  50     {
  51       int errno_saved = errno;
  52       int retval = INLINE_SYSCALL (poll, 3, CHECK_N (fds, nfds), nfds, timeout);
  53
  54       if (retval >= 0 || errno != ENOSYS)
  55         return retval;
  56
  57       __set_errno (errno_saved);
  58       must_emulate = 1;
  59     }
  60
  61   return __emulate_poll (fds, nfds, timeout);
  62 # else
  63   return INLINE_SYSCALL (poll, 3, CHECK_N (fds, nfds), nfds, timeout);
  64 # endif
  65 }
  66 libc_hidden_def (__poll)
  67 weak_alias (__poll, poll)
  68
  69 /* Get the emulation code.  */
  70 # define __poll(fds, nfds, timeout) \
  71   static internal_function __emulate_poll (fds, nfds, timeout)
  72 #endif
  73
  74 #if __ASSUME_POLL_SYSCALL == 0
  75 # include <sysdeps/unix/bsd/poll.c>
  76 #endif