1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License"). You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22 /*
23 * Copyright (c) 1996 by Sun Microsystems, Inc.
24 *
25 * Map in a read-only page of zeroes at location zero, for stupid
26 * programs that think a null pointer is as good as a null string.
27 *
28 * Use:
29 * LD_PRELOAD=0@0.so.1 program args ...
30 *
31 */
32 #pragma ident "%Z%%M% %I% %E% SMI"
33
34 /* LINTLIBRARY */
35
36 #include <sys/types.h>
37 #include <sys/mman.h>
38 #include <fcntl.h>
39 #include <unistd.h>
40
41 #pragma init(__zero_at_zero)
42
43 void
__zero_at_zero()44 __zero_at_zero()
45 {
46 int fd;
47
48 if ((fd = open("/dev/zero", O_RDWR)) < 0)
49 return;
50 (void) mmap(0, 1, PROT_READ, MAP_PRIVATE|MAP_FIXED, fd, 0);
51 (void) close(fd);
52 }
53