1 /*
2 * Copyright (C) 2012 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <string.h>
30 #include <stdlib.h>
31 #include "private/libc_logging.h"
32
33 /*
34 * Runtime implementation of __builtin____strncat_chk.
35 *
36 * See
37 * http://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html
38 * http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html
39 * for details.
40 *
41 * This strncat check is called if _FORTIFY_SOURCE is defined and
42 * greater than 0.
43 */
__strncat_chk(char * __restrict dest,const char * __restrict src,size_t len,size_t dest_buf_size)44 extern "C" char* __strncat_chk(char* __restrict dest, const char* __restrict src,
45 size_t len, size_t dest_buf_size) {
46 if (len == 0) {
47 return dest;
48 }
49
50 size_t dest_len = __strlen_chk(dest, dest_buf_size);
51 char *d = dest + dest_len;
52 dest_buf_size -= dest_len;
53
54 while (*src != '\0') {
55 *d++ = *src++;
56 len--; dest_buf_size--;
57
58 if (__predict_false(dest_buf_size == 0)) {
59 __fortify_chk_fail("strncat: prevented write past end of buffer",
60 BIONIC_EVENT_STRNCAT_BUFFER_OVERFLOW);
61 }
62
63 if (len == 0) {
64 break;
65 }
66 }
67
68 *d = '\0';
69 return dest;
70 }
71