glibc/sysdeps/unix/sysv/linux/x86/gettimeofday.c

/* gettimeofday - get the time.  Linux/x86 version.
   Copyright (C) 2015-2017 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 Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <sys/time.h>

#ifdef SHARED

# include <dl-vdso.h>
# include <errno.h>

static int
__gettimeofday_syscall (struct timeval *tv, struct timezone *tz)
{
  return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
}

# ifndef __gettimeofday_type
/* The i386 gettimeofday.c includes this file with a defined
   __gettimeofday_type macro.  For x86_64 we have to define it to __gettimeofday
   as the internal symbol is the ifunc'ed one.  */
#  define __gettimeofday_type __gettimeofday
# endif

# undef INIT_ARCH
# define INIT_ARCH() PREPARE_VERSION_KNOWN (linux26, LINUX_2_6)
/* If the vDSO is not available we fall back to syscall.  */
libc_ifunc_hidden (__gettimeofday_type, __gettimeofday,
		   (_dl_vdso_vsym ("__vdso_gettimeofday", &linux26)
		    ?: &__gettimeofday_syscall))
libc_hidden_def (__gettimeofday)

#else

# include <sysdep.h>
# include <errno.h>

int
__gettimeofday (struct timeval *tv, struct timezone *tz)
{
  return INLINE_SYSCALL (gettimeofday, 2, tv, tz);
}
libc_hidden_def (__gettimeofday)

#endif
weak_alias (__gettimeofday, gettimeofday)
libc_hidden_weak (gettimeofday)