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/* $OpenBSD: kqueue-flock.c,v 1.4 2016/09/20 23:05:27 bluhm Exp $ */
/*
* Written by Philip Guenther <guenther@openbsd.org> 2012 Public Domain
*/
#include <sys/types.h>
#include <sys/event.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "main.h"
#define FILE "lock.test"
static void
check_lock(int fd, const char *msg)
{
pid_t pid = fork();
int status;
if (pid == -1)
err(1, "fork");
if (pid == 0) {
struct flock fl;
memset(&fl, 0, sizeof fl);
fl.l_type = F_WRLCK;
if (fcntl(fd, F_SETLK, &fl) == 0) {
printf("lock succeeded %s\n", msg);
_exit(1);
}
if (errno != EAGAIN)
err(1, "fcntl(SETLK)");
if (fcntl(fd, F_GETLK, &fl))
err(1, "fcntl(GETLK)");
if (fl.l_type != F_WRLCK) {
printf("lock not found %s\n", msg);
_exit(1);
}
close(fd);
_exit(0);
}
waitpid(pid, &status, 0);
if (! WIFEXITED(status) || WEXITSTATUS(status) != 0)
exit(1);
}
int
do_flock(void)
{
int fd, kq;
struct kevent kev;
struct flock fl;
fd = open(FILE, O_CREAT|O_RDWR, 0666);
if (fd < 0)
err(1, "open");
memset(&fl, 0, sizeof fl);
fl.l_type = F_WRLCK;
if (fcntl(fd, F_SETLK, &fl))
err(1, "fcntl(SETLK)");
check_lock(fd, "before");
kq = kqueue();
EV_SET(&kev, fd, EVFILT_VNODE, EV_ADD, NOTE_LINK, 0, NULL);
if (kevent(kq, &kev, 1, NULL, 0, NULL))
err(1, "kevent");
check_lock(fd, "after add");
EV_SET(&kev, fd, EVFILT_VNODE, EV_DELETE, NOTE_LINK, 0, NULL);
if (kevent(kq, &kev, 1, NULL, 0, NULL))
err(1, "kevent");
check_lock(fd, "after delete");
close(kq);
check_lock(fd, "after kq close");
close(fd);
unlink(FILE);
return (0);
}
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