sysdeps/unix/sysv/linux/eventfd.c

   1 /* Copyright (C) 2007-2015 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    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <sys/eventfd.h>
  20 #include <sysdep.h>
  21 #include <kernel-features.h>
  22
  23
  24 int
  25 eventfd (unsigned int count, int flags)
  26 {
  27 #ifdef __NR_eventfd2
  28 # ifndef __ASSUME_EVENTFD2
  29   INTERNAL_SYSCALL_DECL (err);
  30   int res = INTERNAL_SYSCALL (eventfd2, err, 2, count, flags);
  31   if (!__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (res, err))
  32       || INTERNAL_SYSCALL_ERRNO (res, err) != ENOSYS)
  33     return res;
  34 # endif
  35   return INLINE_SYSCALL_RETURN (eventfd2, 2, int, count, flags);
  36 #endif
  37
  38 #ifndef __ASSUME_EVENTFD2
  39   /* The old system call has no flag parameter which is bad.  So we have
  40      to wait until we have to support to pass additional values to the
  41      kernel (sys_indirect) before implementing setting flags like
  42      O_NONBLOCK etc.  */
  43   if (flags != 0)
  44     return INLINE_SYSCALL_ERROR_RETURN (-EINVAL, int, -1)
  45
  46 # ifdef __NR_eventfd
  47   return INLINE_SYSCALL_RETURN (eventfd, 1, int, count)
  48 # else
  49   return INLINE_SYSCALL_ERROR_RETURN (-ENOSYS, int, -1)
  50 # endif
  51 #elif !defined __NR_eventfd2
  52 # error "__ASSUME_EVENTFD2 defined but not __NR_eventfd2"
  53 #endif
  54 }