1/*
2   Unix SMB/CIFS implementation.
3   Samba utility functions
4   Copyright (C) Martin Pool     2003
5   Copyright (C) Andrew Bartlett 2003
6
7   This program is free software; you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by
9   the Free Software Foundation; either version 2 of the License, or
10   (at your option) any later version.
11
12   This program is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with this program; if not, write to the Free Software
19   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20*/
21
22#include "includes.h"
23
24#ifdef DEVELOPER
25const char *global_clobber_region_function;
26unsigned int global_clobber_region_line;
27#endif
28
29/**
30 * In developer builds, clobber a region of memory.
31 *
32 * If we think a string buffer is longer than it really is, this ought
33 * to make the failure obvious, by segfaulting (if in the heap) or by
34 * killing the return address (on the stack), or by trapping under a
35 * memory debugger.
36 *
37 * This is meant to catch possible string overflows, even if the
38 * actual string copied is not big enough to cause an overflow.
39 *
40 * In addition, under Valgrind the buffer is marked as uninitialized.
41 **/
42void clobber_region(const char *fn, unsigned int line, char *dest, size_t len)
43{
44#ifdef DEVELOPER
45	global_clobber_region_function = fn;
46	global_clobber_region_line = line;
47
48	/* F1 is odd and 0xf1f1f1f1 shouldn't be a valid pointer */
49	memset(dest, 0xF1, len);
50#ifdef VALGRIND
51	/* Even though we just wrote to this, from the application's
52	 * point of view it is not initialized.
53	 *
54	 * (This is not redundant with the clobbering above.  The
55	 * marking might not actually take effect if we're not running
56	 * under valgrind.) */
57	VALGRIND_MAKE_WRITABLE(dest, len);
58#endif /* VALGRIND */
59#endif /* DEVELOPER */
60}
61