/*-
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
* 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 AUTHORS 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 AUTHORS 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.
*/
#include <sys/cdefs.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/capsicum.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <libgen.h>
#include <libutil.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
struct pidfh {
int pf_dirfd;
int pf_fd;
char pf_dir[MAXPATHLEN + 1];
char pf_filename[MAXPATHLEN + 1];
dev_t pf_dev;
ino_t pf_ino;
};
static int _pidfile_remove(struct pidfh *pfh, int freeit);
static int
pidfile_verify(const struct pidfh *pfh)
{
struct stat sb;
if (pfh == NULL || pfh->pf_fd == -1)
return (EDOOFUS);
/*
* Check remembered descriptor.
*/
if (fstat(pfh->pf_fd, &sb) == -1)
return (errno);
if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino)
return (EDOOFUS);
return (0);
}
static int
pidfile_read_impl(int dirfd, const char *filename, pid_t *pidptr)
{
char buf[16], *endptr;
int error, fd, i;
fd = openat(dirfd, filename, O_RDONLY | O_CLOEXEC);
if (fd == -1)
return (errno);
i = read(fd, buf, sizeof(buf) - 1);
error = errno; /* Remember errno in case close() wants to change it. */
close(fd);
if (i == -1)
return (error);
else if (i == 0)
return (EAGAIN);
buf[i] = '\0';
*pidptr = strtol(buf, &endptr, 10);
if (endptr != &buf[i])
return (EINVAL);
return (0);
}
static int
pidfile_read(int dirfd, const char *filename, pid_t *pidptr)
{
struct timespec rqtp;
int count;
count = 20;
rqtp.tv_sec = 0;
rqtp.tv_nsec = 5000000;
for (;;) {
errno = pidfile_read_impl(dirfd, filename, pidptr);
if (errno != EAGAIN || --count == 0)
break;
nanosleep(&rqtp, 0);
}
if (errno == EAGAIN)
*pidptr = -1;
return (errno);
}
struct pidfh *
pidfile_open(const char *pathp, mode_t mode, pid_t *pidptr)
{
char path[MAXPATHLEN];
struct pidfh *pfh;
struct stat sb;
int error, fd, dirfd, dirlen, filenamelen;
cap_rights_t caprights;
pfh = malloc(sizeof(*pfh));
if (pfh == NULL)
return (NULL);
if (pathp == NULL) {
dirlen = snprintf(pfh->pf_dir, sizeof(pfh->pf_dir),
"/var/run/");
filenamelen = snprintf(pfh->pf_filename,
sizeof(pfh->pf_filename), "%s.pid", getprogname());
} else {
if (strlcpy(path, pathp, sizeof(path)) >= sizeof(path)) {
free(pfh);
errno = ENAMETOOLONG;
return (NULL);
}
dirlen = strlcpy(pfh->pf_dir, dirname(path),
sizeof(pfh->pf_dir));
(void)strlcpy(path, pathp, sizeof(path));
filenamelen = strlcpy(pfh->pf_filename, basename(path),
sizeof(pfh->pf_filename));
}
if (dirlen >= (int)sizeof(pfh->pf_dir) ||
filenamelen >= (int)sizeof(pfh->pf_filename)) {
free(pfh);
errno = ENAMETOOLONG;
return (NULL);
}
dirfd = open(pfh->pf_dir, O_CLOEXEC | O_DIRECTORY | O_NONBLOCK);
if (dirfd == -1) {
error = errno;
free(pfh);
errno = error;
return (NULL);
}
/*
* Open the PID file and obtain exclusive lock.
* We truncate PID file here only to remove old PID immediately,
* PID file will be truncated again in pidfile_write(), so
* pidfile_write() can be called multiple times.
*/
fd = flopenat(dirfd, pfh->pf_filename,
O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NONBLOCK, mode);
if (fd == -1) {
if (errno == EWOULDBLOCK) {
if (pidptr == NULL) {
errno = EEXIST;
} else {
errno = pidfile_read(dirfd,
pfh->pf_filename, pidptr);
if (errno == 0 || errno == EAGAIN)
errno = EEXIST;
}
}
error = errno;
close(dirfd);
free(pfh);
errno = error;
return (NULL);
}
/*
* Remember file information, so in pidfile_write() we are sure we write
* to the proper descriptor.
*/
if (fstat(fd, &sb) == -1) {
goto failed;
}
if (cap_rights_limit(dirfd,
cap_rights_init(&caprights, CAP_UNLINKAT)) < 0 && errno != ENOSYS) {
goto failed;
}
if (cap_rights_limit(fd, cap_rights_init(&caprights, CAP_PWRITE,
CAP_FSTAT, CAP_FTRUNCATE, CAP_EVENT)) < 0 &&
errno != ENOSYS) {
goto failed;
}
pfh->pf_dirfd = dirfd;
pfh->pf_fd = fd;
pfh->pf_dev = sb.st_dev;
pfh->pf_ino = sb.st_ino;
return (pfh);
failed:
error = errno;
unlinkat(dirfd, pfh->pf_filename, 0);
close(dirfd);
close(fd);
free(pfh);
errno = error;
return (NULL);
}
int
pidfile_write(struct pidfh *pfh)
{
char pidstr[16];
int error, fd;
/*
* Check remembered descriptor, so we don't overwrite some other
* file if pidfile was closed and descriptor reused.
*/
errno = pidfile_verify(pfh);
if (errno != 0) {
/*
* Don't close descriptor, because we are not sure if it's ours.
*/
return (-1);
}
fd = pfh->pf_fd;
/*
* Truncate PID file, so multiple calls of pidfile_write() are allowed.
*/
if (ftruncate(fd, 0) == -1) {
error = errno;
_pidfile_remove(pfh, 0);
errno = error;
return (-1);
}
snprintf(pidstr, sizeof(pidstr), "%u", getpid());
if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) {
error = errno;
_pidfile_remove(pfh, 0);
errno = error;
return (-1);
}
return (0);
}
int
pidfile_close(struct pidfh *pfh)
{
int error;
error = pidfile_verify(pfh);
if (error != 0) {
errno = error;
return (-1);
}
if (close(pfh->pf_fd) == -1)
error = errno;
if (close(pfh->pf_dirfd) == -1 && error == 0)
error = errno;
free(pfh);
if (error != 0) {
errno = error;
return (-1);
}
return (0);
}
static int
_pidfile_remove(struct pidfh *pfh, int freeit)
{
int error;
error = pidfile_verify(pfh);
if (error != 0) {
errno = error;
return (-1);
}
if (funlinkat(pfh->pf_dirfd, pfh->pf_filename, pfh->pf_fd, 0) == -1) {
if (errno == EDEADLK)
return (-1);
error = errno;
}
if (close(pfh->pf_fd) == -1 && error == 0)
error = errno;
if (close(pfh->pf_dirfd) == -1 && error == 0)
error = errno;
if (freeit)
free(pfh);
else
pfh->pf_fd = -1;
if (error != 0) {
errno = error;
return (-1);
}
return (0);
}
int
pidfile_remove(struct pidfh *pfh)
{
return (_pidfile_remove(pfh, 1));
}
int
pidfile_fileno(const struct pidfh *pfh)
{
if (pfh == NULL || pfh->pf_fd == -1) {
errno = EDOOFUS;
return (-1);
}
return (pfh->pf_fd);
}
int
pidfile_signal(const char *pathp, int sig, pid_t *pidptr)
{
pid_t pid;
int fd;
fd = flopenat(AT_FDCWD, pathp,
O_RDONLY | O_CLOEXEC | O_NONBLOCK);
if (fd >= 0) {
/*
* The file exists but is not locked,
* so the daemon is dead. Nothing to do.
*/
close(fd);
errno = ENOENT;
return (errno);
}
if (errno != EWOULDBLOCK) {
return (errno);
}
errno = pidfile_read(AT_FDCWD, pathp, &pid);
if (errno != 0)
return (errno);
/*
* Refuse to send broadcast or group signals, this has
* happened due to the bugs in pidfile(3).
*/
if (pid <= 0)
return (EDOM);
kill(pid, sig);
if (pidptr != NULL)
*pidptr = pid;
return (errno);
}
