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dch/daemon.c

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daemon.c from FreeBSD 11.0
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daemon.c
/*-
* Copyright (c) 1999 Berkeley Software Design, Inc. 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.
* 3. Berkeley Software Design Inc's name may not be used to endorse or
* promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``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 BERKELEY SOFTWARE DESIGN INC 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.
*
* From BSDI: daemon.c,v 1.2 1996/08/15 01:11:09 jch Exp
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/mman.h>
#include <sys/wait.h>
#include <err.h>
#include <errno.h>
#include <libutil.h>
#include <login_cap.h>
#include <pwd.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
static void dummy_sighandler(int);
static void restrict_process(const char *);
static int wait_child(pid_t pid, sigset_t *mask);
static void usage(void);
int
main(int argc, char *argv[])
{
struct pidfh *ppfh, *pfh;
sigset_t mask, oldmask;
int ch, nochdir, noclose, nohup, restart, serrno;
const char *pidfile, *ppidfile, *title, *user;
pid_t otherpid, pid;
nochdir = noclose = 1;
restart = nohup = 0 ;
ppidfile = pidfile = title = user = NULL;
while ((ch = getopt(argc, argv, "cfp:P:rt:u:H")) != -1) {
switch (ch) {
case 'c':
nochdir = 0;
break;
case 'f':
noclose = 0;
break;
case 'p':
pidfile = optarg;
break;
case 'P':
ppidfile = optarg;
break;
case 'r':
restart = 1;
break;
case 't':
title = optarg;
break;
case 'u':
user = optarg;
break;
case 'H':
nohup = 1;
break;
default:
usage();
}
}
argc -= optind;
argv += optind;
if (argc == 0)
usage();
ppfh = pfh = NULL;
/*
* Try to open the pidfile before calling daemon(3),
* to be able to report the error intelligently
*/
if (pidfile != NULL) {
pfh = pidfile_open(pidfile, 0600, &otherpid);
if (pfh == NULL) {
if (errno == EEXIST) {
errx(3, "process already running, pid: %d",
otherpid);
}
err(2, "pidfile ``%s''", pidfile);
}
}
/* Do the same for actual daemon process. */
if (ppidfile != NULL) {
ppfh = pidfile_open(ppidfile, 0600, &otherpid);
if (ppfh == NULL) {
serrno = errno;
pidfile_remove(pfh);
errno = serrno;
if (errno == EEXIST) {
errx(3, "process already running, pid: %d",
otherpid);
}
err(2, "ppidfile ``%s''", ppidfile);
}
}
if (daemon(nochdir, noclose) == -1) {
warn("daemon");
goto exit;
}
/* Write out parent pidfile if needed. */
pidfile_write(ppfh);
/*
* If the pidfile or restart option is specified the daemon
* executes the command in a forked process and wait on child
* exit to remove the pidfile or restart the command. Normally
* we don't want the monitoring daemon to be terminated
* leaving the running process and the stale pidfile, so we
* catch SIGTERM and forward it to the children expecting to
* get SIGCHLD eventually.
*/
pid = -1;
if (pidfile != NULL || ppidfile != NULL || restart) {
/*
* Restore default action for SIGTERM in case the
* parent process decided to ignore it.
*/
if (signal(SIGTERM, SIG_DFL) == SIG_ERR) {
warn("signal");
goto exit;
}
/*
* Because SIGCHLD is ignored by default, setup dummy handler
* for it, so we can mask it.
*/
if (signal(SIGCHLD, dummy_sighandler) == SIG_ERR) {
warn("signal");
goto exit;
}
/*
* Block interesting signals.
*/
sigemptyset(&mask);
sigaddset(&mask, SIGTERM);
sigaddset(&mask, SIGCHLD);
if (nohup) {
sigaddset(&mask, SIGHUP);
}
if (sigprocmask(SIG_SETMASK, &mask, &oldmask) == -1) {
warn("sigprocmask");
goto exit;
}
/*
* Try to protect against pageout kill. Ignore the
* error, madvise(2) will fail only if a process does
* not have superuser privileges.
*/
(void)madvise(NULL, 0, MADV_PROTECT);
restart:
/*
* Spawn a child to exec the command, so in the parent
* we could wait for it to exit and remove pidfile.
*/
pid = fork();
if (pid == -1) {
warn("fork");
goto exit;
}
}
if (pid <= 0) {
if (pid == 0) {
/* Restore old sigmask in the child. */
if (sigprocmask(SIG_SETMASK, &oldmask, NULL) == -1)
err(1, "sigprocmask");
}
/* Now that we are the child, write out the pid. */
pidfile_write(pfh);
if (user != NULL)
restrict_process(user);
execvp(argv[0], argv);
/*
* execvp() failed -- report the error. The child is
* now running, so the exit status doesn't matter.
*/
err(1, "%s", argv[0]);
}
if (title != NULL)
setproctitle("%s[%d]", title, pid);
else
setproctitle("%s[%d]", argv[0], pid);
if (wait_child(pid, &mask) == 0 && restart) {
sleep(1);
goto restart;
}
exit:
pidfile_remove(pfh);
pidfile_remove(ppfh);
exit(1); /* If daemon(3) succeeded exit status does not matter. */
}
static void
dummy_sighandler(int sig __unused)
{
/* Nothing to do. */
}
static void
restrict_process(const char *user)
{
struct passwd *pw = NULL;
pw = getpwnam(user);
if (pw == NULL)
errx(1, "unknown user: %s", user);
if (setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0)
errx(1, "failed to set user environment");
}
static int
wait_child(pid_t pid, sigset_t *mask)
{
int terminate, signo;
terminate = 0;
for (;;) {
if (sigwait(mask, &signo) == -1) {
warn("sigwaitinfo");
return (-1);
}
switch (signo) {
case SIGCHLD:
if (waitpid(pid, NULL, WNOHANG) == -1) {
warn("waitpid");
return (-1);
}
return (terminate);
case SIGTERM:
terminate = 1;
if (kill(pid, signo) == -1) {
warn("kill");
return (-1);
}
continue;
case SIGHUP:
if (nohup) {}
if (kill(pid, signo) == -1) {
warn("hup");
return (-1);
}
continue; default:
warnx("sigwaitinfo: invalid signal: %d", signo);
return (-1);
}
}
}
static void
usage(void)
{
(void)fprintf(stderr, "%s\n\t%s\n",
"usage: daemon [-cfrH] [-p child_pidfile] [-P supervisor_pidfile]",
"[-t title] [-u user] command arguments ...");
exit(1);
}
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