__strcpy_chk.cpp revision 950a58e24d1019eb9d814dbb16f111a6b61e3f23 
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#undef _FORTIFY_SOURCE
30
31#include <string.h>
32#include <stdlib.h>
33#include "private/libc_logging.h"
34
35/*
36 * Runtime implementation of __builtin____strcpy_chk.
37 *
38 * See
39 *   http://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html
40 *   http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html
41 * for details.
42 *
43 * This strcpy check is called if _FORTIFY_SOURCE is defined and
44 * greater than 0.
45 */
46extern "C" char* __strcpy_chk(char* dest, const char* src, size_t dest_len) {
47  // TODO: optimize so we don't scan src twice.
48  size_t src_len = strlen(src) + 1;
49  if (__predict_false(src_len > dest_len)) {
50    __fortify_chk_fail("strcpy: prevented write past end of buffer",
51                       BIONIC_EVENT_STRCPY_BUFFER_OVERFLOW);
52  }
53
54  return strcpy(dest, src);
55}
56