mmapwrite.c revision d583b39bfb4e2571d3e41097c5c357ffe353ad45
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2007 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <pthread.h>
/*
* --------------------------------------------------------------------
* Bug Id: 5032643
*
* Simply writing to a file and mmaping that file at the same time can
* result in deadlock. Nothing perverse like writing from the file's
* own mapping is required.
* --------------------------------------------------------------------
*/
static void *
mapper(void *fdp)
{
void *addr;
int fd = *(int *)fdp;
if ((addr =
mmap(0, 8192, PROT_READ, MAP_SHARED, fd, 0)) == MAP_FAILED) {
perror("mmap");
exit(1);
}
for (;;) {
if (mmap(addr, 8192, PROT_READ,
MAP_SHARED|MAP_FIXED, fd, 0) == MAP_FAILED) {
perror("mmap");
exit(1);
}
}
/* NOTREACHED */
return ((void *)1);
}
int
main(int argc, char **argv)
{
int fd;
char buf[BUFSIZ];
if (argc != 2) {
(void) printf("usage: %s <file name>\n", argv[0]);
exit(1);
}
if ((fd = open(argv[1], O_RDWR|O_CREAT|O_TRUNC, 0666)) == -1) {
perror("open");
exit(1);
}
if (pthread_create(NULL, NULL, mapper, &fd) != 0) {
perror("pthread_create");
exit(1);
}
for (;;) {
if (write(fd, buf, sizeof (buf)) == -1) {
perror("write");
exit(1);
}
}
/* NOTREACHED */
return (0);
}