#!/bin/sh
#
# Copyright (c) 2012 Peter Holm
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
# Demonstrate that close() of an flock'd file is not atomic.
# Fails with "flock_open_close: execv(/mnt/test): Text file busy"
# Test scenario by: jhb
[ `id -u ` -ne 0 ] && echo "Must be root!" && exit 1
. ../default.cfg
odir=`pwd`
cd /tmp
sed '1,/^EOF/d' < $odir/$0 > flock_open_close.c
rm -f /tmp/flock_open_close
mycc -o flock_open_close -Wall -Wextra -O2 -g flock_open_close.c -lpthread || exit 1
rm -f flock_open_close.c
mount | grep $mntpoint | grep -q /dev/md && umount -f $mntpoint
mdconfig -l | grep -q md$mdstart && mdconfig -d -u $mdstart
mdconfig -a -t swap -s 1g -u $mdstart || exit 1
bsdlabel -w md$mdstart auto
newfs $newfs_flags md${mdstart}$part > /dev/null
mount /dev/md${mdstart}$part $mntpoint
chmod 777 $mntpoint
cp /bin/test $mntpoint
chown $testuser $mntpoint/test
chmod +w $mntpoint/test
su $testuser -c "/tmp/flock_open_close $mntpoint/test" &
pid=$!
while kill -0 $! 2>/dev/null; do
mksnap_ffs $mntpoint $mntpoint/.snap/snap
sleep 2
rm -f $mntpoint/.snap/snap
sleep 1
done
wait $pid
s=$?
for i in `jot 10`; do
mount | grep -q md${mdstart}$part && \
umount $mntpoint && mdconfig -d -u $mdstart && break
sleep 2
done
if mount | grep -q md${mdstart}$part; then
fstat $mntpoint
echo "umount $mntpoint failed"
exit 1
fi
rm -f /tmp/flock_open_close
exit $s
EOF
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
static void
usage(void)
{
fprintf(stderr, "Usage: flock_close_race <binary> [args]\n");
exit(1);
}
static void
child(const char *binary)
{
int fd;
/* Exit as soon as our parent exits. */
while (getppid() != 1) {
fd = open(binary, O_RDWR | O_EXLOCK);
if (fd < 0) {
/*
* This may get ETXTBSY since exit() will
* close its open fd's (thus releasing the
* lock), before it releases the vmspace (and
* mapping of the binary).
*/
if (errno == ETXTBSY)
continue;
err(2, "can't open %s", binary);
}
close(fd);
}
exit(0);
}
static void
exec_child(char **av)
{
int fd;
fd = open(av[0], O_RDONLY | O_SHLOCK);
execv(av[0], av);
/* "flock_open_close: execv(/mnt/test): Text file busy" seen */
err(127, "execv(%s)", av[0]);
}
int
main(int ac, char **av)
{
struct stat sb;
pid_t pid;
int e, i, status;
if (ac < 2)
usage();
if (stat(av[1], &sb) != 0)
err(1, "stat(%s)", av[1]);
if (!S_ISREG(sb.st_mode))
errx(1, "%s not an executable", av[1]);
pid = fork();
if (pid < 0)
err(1, "fork");
if (pid == 0)
child(av[1]);
e = 0;
for (i = 0; i < 200000; i++) {
pid = fork();
if (pid < 0)
err(1, "vfork");
if (pid == 0)
exec_child(av + 1);
wait(&status);
if (WIFEXITED(status) && WEXITSTATUS(status) == 127) {
fprintf(stderr, "FAIL\n");
e = 1;
break;
}
if (WIFEXITED(status) && WEXITSTATUS(status) != 1) {
/* /bin/test returns 1 */
e = 1;
break;
}
}
return (e);
}
