/*
* Copyright (c) 2013 Ralph Irving
*
* daemonize.c is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* daemonize.c is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with SlimProtoLib; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "squeezelite.h"
#include <syslog.h>
#include <sys/stat.h>
void fork_child_handler(int signum)
{
switch(signum) {
case SIGALRM: exit(EXIT_FAILURE); break;
case SIGUSR1: exit(EXIT_SUCCESS); break;
case SIGCHLD: exit(EXIT_FAILURE); break;
}
}
pid_t parent;
void init_daemonize()
{
pid_t pid, sid;
/* already a daemon */
if ( getppid() == 1 ) return;
/* Trap signals that we expect to recieve */
signal(SIGCHLD,fork_child_handler);
signal(SIGUSR1,fork_child_handler);
signal(SIGALRM,fork_child_handler);
/* Fork off the parent process */
pid = fork();
if (pid < 0) {
syslog( LOG_ERR, "unable to fork daemon, code=%d (%s)",
errno, strerror(errno) );
exit(EXIT_FAILURE);
}
/* If we got a good PID, then we can exit the parent process. */
if (pid > 0) {
/* Wait for confirmation from the child via SIGTERM or SIGCHLD, or
for two seconds to elapse (SIGALRM). pause() should not return. */
alarm(2);
pause();
exit(EXIT_FAILURE);
}
/* At this point we are executing as the child process */
parent = getppid();
/* Cancel certain signals */
signal(SIGCHLD,SIG_DFL); /* A child process dies */
signal(SIGTSTP,SIG_IGN); /* Various TTY signals */
signal(SIGTTOU,SIG_IGN);
signal(SIGTTIN,SIG_IGN);
signal(SIGHUP, SIG_IGN); /* Ignore hangup signal */
signal(SIGTERM,SIG_DFL); /* Die on SIGTERM */
/* Change the file mode mask */
umask(0);
/* Create a new SID for the child process */
sid = setsid();
if (sid < 0) {
syslog( LOG_ERR, "unable to create a new session, code %d (%s)",
errno, strerror(errno) );
exit(EXIT_FAILURE);
}
/* Change the current working directory. This prevents the current
directory from being locked; hence not being able to remove it. */
if ((chdir("/")) < 0) {
syslog( LOG_ERR, "unable to change directory to %s, code %d (%s)",
"/", errno, strerror(errno) );
exit(EXIT_FAILURE);
}
}
int daemon( int nochdir, int noclose ) {
if ( ! noclose )
{
/* Redirect standard files to /dev/null */
freopen( "/dev/null", "r", stdin);
freopen( "/dev/null", "w", stdout);
freopen( "/dev/null", "w", stderr);
}
/* Tell the parent process that we are A-okay */
kill( parent, SIGUSR1 );
return 0;
}