1

蓝牙

/* Change this to the user under which to run */
#define RUN_AS_USER "root"

#define EXIT_SUCCESS 0
#define EXIT_FAILURE 1

#if 0
static void child_handler(int signum)
{
    switch(signum)
	{
    case SIGALRM: exit(EXIT_FAILURE); break;
    case SIGUSR1: exit(EXIT_SUCCESS); break;
    case SIGCHLD: exit(EXIT_FAILURE); break;
    }
}

static void daemonize(const char *lockfile)
{
    pid_t pid, sid, parent;
    int lfp = -1;

    /* already a daemon */
    if (getppid() == 1) return;

    /* Create the lock file as the current user */
    if (lockfile && lockfile[0])
	{
        lfp = open(lockfile,O_RDWR|O_CREAT,0640);
        if (lfp < 0) {
            printf("unable to create lock file %s, code=%d (%s)",
                    lockfile, errno, strerror(errno));
            exit(EXIT_FAILURE);
        }
    }

    /* Drop user if there is one, and we were run as root */
    if ( getuid() == 0 || geteuid() == 0 ) {
        struct passwd *pw = getpwnam(RUN_AS_USER);
        if (pw) {
            printf("setting user to " RUN_AS_USER);
            setuid( pw->pw_uid );
        }
    }

    /* Trap signals that we expect to recieve */
    signal(SIGCHLD, child_handler);
    signal(SIGUSR1, child_handler);
    signal(SIGALRM, child_handler);

    /* Fork off the parent process */
    pid = fork();
    if (pid < 0) {
        printf("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) {
        printf("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) {
        printf("unable to change directory to %s, code %d (%s)",
                "/", errno, strerror(errno) );
        exit(EXIT_FAILURE);
    }

    /* 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 );
}
#endif