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 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