getpagesize.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

/* Copyright (C) 1999, 2000, 2001, 2002, 2004 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 <assert.h>
#include <unistd.h>
#include <sys/param.h>

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

/* Return the system page size.  The return value will depend on how
   the kernel is configured.  A program must use this call to
   determine the page size to ensure proper alignment for calls such
   as mmap and friends.  --davidm 99/11/30 */

int
__getpagesize ()
{
  assert (GLRO(dl_pagesize) != 0);
  return GLRO(dl_pagesize);
}
libc_hidden_def (__getpagesize)
weak_alias (__getpagesize, getpagesize)