sync_file_range.c

glibc 库, 不仅可以学习使用库函数,还可以学习函数的具体实现,是提高功力的好资料

/* Selective file content synch'ing.
   Copyright (C) 2006, 2007 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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>

#include <sysdep.h>
#include <sys/syscall.h>


#ifdef __NR_sync_file_range
int
sync_file_range (int fd, __off64_t from, __off64_t to, unsigned int flags)
{
  return INLINE_SYSCALL (sync_file_range, 6, fd,
			 __LONG_LONG_PAIR ((long) (from >> 32), (long) from),
			 __LONG_LONG_PAIR ((long) (to >> 32), (long) to),
			 flags);
}
#else
int
sync_file_range (int fd, __off64_t from, __off64_t to, unsigned int flags)
{
  __set_errno (ENOSYS);
  return -1;
}
stub_warning (sync_file_range)

# include <stub-tag.h>
#endif