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 (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2007 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 #pragma ident "@(#)mmapwrite.c 1.4 07/05/25 SMI" 28 29 #include <unistd.h> 30 #include <fcntl.h> 31 #include <stdio.h> 32 #include <stdlib.h> 33 #include <sys/mman.h> 34 #include <pthread.h> 35 36 /* 37 * -------------------------------------------------------------------- 38 * Bug Id: 5032643 39 * 40 * Simply writing to a file and mmaping that file at the same time can 41 * result in deadlock. Nothing perverse like writing from the file's 42 * own mapping is required. 43 * -------------------------------------------------------------------- 44 */ 45 46 static void * 47 mapper(void *fdp) 48 { 49 void *addr; 50 int fd = *(int *)fdp; 51 52 if ((addr = 53 mmap(0, 8192, PROT_READ, MAP_SHARED, fd, 0)) == MAP_FAILED) { 54 perror("mmap"); 55 exit(1); 56 } 57 for (;;) { 58 if (mmap(addr, 8192, PROT_READ, 59 MAP_SHARED|MAP_FIXED, fd, 0) == MAP_FAILED) { 60 perror("mmap"); 61 exit(1); 62 } 63 } 64 /* NOTREACHED */ 65 return ((void *)1); 66 } 67 68 int 69 main(int argc, char **argv) 70 { 71 int fd; 72 char buf[BUFSIZ]; 73 pthread_t pt; 74 75 if (argc != 2) { 76 (void) printf("usage: %s <file name>\n", argv[0]); 77 exit(1); 78 } 79 80 if ((fd = open(argv[1], O_RDWR|O_CREAT|O_TRUNC, 0666)) == -1) { 81 perror("open"); 82 exit(1); 83 } 84 85 if (pthread_create(&pt, NULL, mapper, &fd) != 0) { 86 perror("pthread_create"); 87 exit(1); 88 } 89 for (;;) { 90 if (write(fd, buf, sizeof (buf)) == -1) { 91 perror("write"); 92 exit(1); 93 } 94 } 95 96 /* NOTREACHED */ 97 return (0); 98 } 99