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/* $OpenBSD: blocked_fifo.c,v 1.1 2012/03/19 17:41:57 oga Exp $ */
/*
* Copyright (c) 2012 Owain G. Ainsworth <oga@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* Test fifo opening blocking the file descriptor table and thus all other
* opens in the process.
* Symptoms are that the main thread will sleep on fifor (in the fifo open) and
* the deadlocker on fdlock (in open of any other file).
*/
#include <sys/types.h>
#include <sys/stat.h>
#include <pthread.h>
#include <unistd.h>
#include <fcntl.h>
#include "test.h"
#define FIFO "/tmp/pthread.fifo"
#define FILE "/etc/services" /* just any file to deadlock on */
static void *
deadlock_detector(void *arg)
{
sleep(10);
unlink(FIFO);
PANIC("deadlock detected");
}
static void *
fifo_deadlocker(void *arg)
{
int fd;
/* let other fifo open start */
sleep(3);
/* open a random temporary file, if we don't deadlock this'll succeed */
CHECKe(fd = open(FILE, O_RDONLY));
CHECKe(close(fd));
/* open fifo to unblock other thread */
CHECKe(fd = open(FIFO, O_WRONLY));
return ((caddr_t)NULL + errno);
}
int
main(int argc, char *argv[])
{
pthread_t deadlock_thread, deadlock_finder;
int fd;
CHECKe(mkfifo(FIFO, S_IRUSR | S_IWUSR));
CHECKr(pthread_create(&deadlock_thread, NULL,
fifo_deadlocker, NULL));
CHECKr(pthread_create(&deadlock_finder, NULL,
deadlock_detector, NULL));
/* Open fifo (this will sleep until we have readers */
CHECKe(fd = open(FIFO, O_RDONLY));
CHECKr(pthread_join(deadlock_thread, NULL));
unlink(FIFO);
SUCCEED;
}
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