Libc-594.9.4.tar.gz

[apple/libc.git] / secure / strcat_chk.c

/*
 * Copyright (c) 2007 Apple Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_LICENSE_HEADER_END@
 */

#include <stdlib.h>
#include <string.h>
#include <stdio.h>

extern void __chk_fail (void) __attribute__((__noreturn__));

char *
__strcat_chk (char *__restrict s, const char *__restrict append,
	      size_t slen)
{
  char *save = s;

  /* Advance to the end. */
  for (; *s; ++s)
    if (__builtin_expect (slen-- == 0, 0))
      __chk_fail ();

  do
    {
      /* Append the string.  Make sure we check before writing.  */
      if (__builtin_expect (slen-- == 0, 0))
	__chk_fail ();

    } while (*s++ = *append++);

  return save;

}