daemonize.c

#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <syslog.h>
#include <string.h>
#include "daemonize.h"

void daemonize()
{
  /* Our process ID and Session ID */
  pid_t pid, sid;

  /* Fork off the parent process */
  pid = fork();
  if (pid < 0)
  {
    exit(EXIT_FAILURE);
  }

  /* If we got a good PID, then
     we can exit the parent process. */
  if (pid > 0)
  {
    exit(EXIT_SUCCESS);
  }

  /* Change the file mode mask */
  umask(0);

  /* Create a new SID for the child process */
  sid = setsid();
  if (sid < 0)
  {
    /* Log the failure */
    exit(EXIT_FAILURE);
  }

  /* Change the current working directory */
  if ((chdir("/")) < 0)
  {
    /* Log the failure */
    exit(EXIT_FAILURE);
  }

  /* Close out the standard file descriptors */
  close(STDIN_FILENO);
  close(STDOUT_FILENO);
  close(STDERR_FILENO);
}