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