1  /*
 2   * Copyright (c) 2010-2013 Apple Inc. All rights reserved.
 3   *
 4   * @APPLE_LICENSE_HEADER_START@
 5   *
 6   * This file contains Original Code and/or Modifications of Original Code
 7   * as defined in and that are subject to the Apple Public Source License
 8   * Version 2.0 (the 'License'). You may not use this file except in
 9   * compliance with the License. Please obtain a copy of the License at
10   * http://www.opensource.apple.com/apsl/ and read it before using this
11   * file.
12   *
13   * The Original Code and all software distributed under the License are
14   * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
15   * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
16   * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
17   * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
18   * Please see the License for the specific language governing rights and
19   * limitations under the License.
20   *
21   * @APPLE_LICENSE_HEADER_END@
22   */
23  
24  #include <stdlib.h>
25  #include <string.h>
26  #include "secure.h"
27  
28  char *
29  __stpncpy_chk (char *restrict dest, char *restrict src,
30  	       size_t len, size_t dstlen)
31  {
32    size_t n;
33    char *retval;
34  
35    if (__builtin_expect (dstlen < len, 0))
36      __chk_fail_overflow ();
37  
38    retval = stpncpy (dest, src, len); // Normally returns a pointer to the \0
39    n = retval - dest + 1;
40  
41    // Check if it's pointing to the location after the buffer after not writing \0
42    if (n == len + 1)
43      n--;
44  
45    if (__builtin_expect (__chk_assert_no_overlap != 0, 1))
46      __chk_overlap(dest, n, src, n);
47  
48    return retval;
49  }