memset_chk.s

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

/* Checking memset for i686.
   Copyright (C) 2004, 2005 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 <sysdep.h>
#include "asm-syntax.h"

#ifndef PIC
	/* For libc.so this is defined in memset.S.
	   For libc.a, this is a separate source to avoid
	   memset bringing in __chk_fail and all routines
	   it calls.  */
        .text
ENTRY (__memset_chk)
	movl	12(%esp), %eax
	cmpl	%eax, 16(%esp)
	jb	__chk_fail
	jmp	memset
END (__memset_chk)
#endif