83 lines
1.6 KiB
C
83 lines
1.6 KiB
C
/*
|
|
* daemonise.c:
|
|
* Fairly generic "Turn the current process into a daemon" code.
|
|
*
|
|
* Copyright (c) 2016-2017 Gordon Henderson.
|
|
*********************************************************************************
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#include <syslog.h>
|
|
#include <signal.h>
|
|
#include <sys/stat.h>
|
|
|
|
#include "daemonise.h"
|
|
|
|
void daemonise (const char *pidFile)
|
|
{
|
|
pid_t pid ;
|
|
int i ;
|
|
FILE *fd ;
|
|
|
|
syslog (LOG_DAEMON | LOG_INFO, "Becoming daemon") ;
|
|
|
|
// Fork from the parent
|
|
|
|
if ((pid = fork ()) < 0)
|
|
{
|
|
syslog (LOG_DAEMON | LOG_ALERT, "Fork no. 1 failed: %m") ;
|
|
exit (EXIT_FAILURE) ;
|
|
}
|
|
|
|
if (pid > 0) // Parent - terminate
|
|
exit (EXIT_SUCCESS) ;
|
|
|
|
// Now running on the child - become session leader
|
|
|
|
if (setsid() < 0)
|
|
{
|
|
syslog (LOG_DAEMON | LOG_ALERT, "setsid failed: %m") ;
|
|
exit (EXIT_FAILURE) ;
|
|
}
|
|
|
|
// Ignore a few signals
|
|
|
|
signal (SIGCHLD, SIG_IGN) ;
|
|
signal (SIGHUP, SIG_IGN) ;
|
|
|
|
// Fork again
|
|
|
|
if ((pid = fork ()) < 0)
|
|
{
|
|
syslog (LOG_DAEMON | LOG_ALERT, "Fork no. 2 failed: %m") ;
|
|
exit (EXIT_FAILURE) ;
|
|
}
|
|
|
|
if (pid > 0) // parent - terminate
|
|
exit (EXIT_SUCCESS) ;
|
|
|
|
// Tidying up - reset umask, change to / and close all files
|
|
|
|
umask (0) ;
|
|
chdir ("/") ;
|
|
|
|
for (i = 0 ; i < sysconf (_SC_OPEN_MAX) ; ++i)
|
|
close (i) ;
|
|
|
|
// Write PID into /var/run
|
|
|
|
if (pidFile != NULL)
|
|
{
|
|
if ((fd = fopen (pidFile, "w")) == NULL)
|
|
{
|
|
syslog (LOG_DAEMON | LOG_ALERT, "Unable to write PID file: %m") ;
|
|
exit (EXIT_FAILURE) ;
|
|
}
|
|
|
|
fprintf (fd, "%d\n", getpid ()) ;
|
|
fclose (fd) ;
|
|
}
|
|
}
|