Something

#include <stdio.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/poll.h>
#include <sys/gpio.h>
#include <net/if.h>
#include <net/bpf.h>
#include <errno.h>
#include <err.h>
#include <fcntl.h>
#include <ifaddrs.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <stdarg.h>
#include <stdlib.h>
#include <sysexits.h>
#include <util.h>
#include <unistd.h>

#define SNAPLEN 64

//
static int devfd = -1;
static int led = 0;
static int led_on_val = GPIO_PIN_HIGH;
static int led_off_val = GPIO_PIN_LOW;
static char *device = "/dev/gpio0";

extern char *__progname;

static void usage(char *device, int to_ms)
{
    fprintf(stderr, "\nUsage: %s [options]\n"
	    " Options:\n"
	    "  -f                foreground [off]\n"
	    "  -d device         gpio device [%s]\n"
	    "  -t milliseconds   minimum period to keep LED active [%d]\n"
	    "  -n                don't monopolize gpio device\n"
	    "  -r                invert LED behavior\n"
	    "  -P                write pidfile [off]\n"
	    "  -B basename       pidfile basename (implies -P) [%s]\n"
	    " Version: 0.1\n",
	    __progname, device, to_ms, __progname);

    exit(EX_USAGE);
}

#define LED_STD 1
#define LED_SIG	2

static int (*gpio_ioctl)(int, unsigned long, ...) = NULL;

static int my_ioctl(int d, unsigned long request, ...)
{
    int res = d = open(device, O_RDWR);
    if (d > -1)
    {
	va_list ap;
	va_start(ap, request);
	res = ioctl(d, request, va_arg(ap, struct gpio_pin_op *));
	close (d);
	va_end(ap);
    }
    return res;
}

static void mod_led(gpio_pin_op led, int led_state)
{
    if(led_state == 0) {
        led.gp_value = led_on_val;
    }
    else {
        led.gp_value = led_off_val;
    }
    gpio_ioctl(devfd, GPIOPINWRITE, &led);
}

static void bye(int unused)
{
    exit(-1);
}


int main(int argc, char **argv)
{
    char *pid_base = __progname;
    char buf[SNAPLEN];
    int ch, r;
    int foreground = 0;
    int opt_ms = 100;
    int opt_pidfile = 0;
    int initial = -1;
    struct gpio_pin_op op[8];
  


    gpio_ioctl = ioctl;

    memset(&op, 0, sizeof(op));
    op[0].gp_pin = 9;		/* suitable for Soekris Net4501 */

    while ((ch = getopt(argc, argv, "d:fhi:p:t:PB:I:rn")) != -1) {
	switch (ch) {
	case 'd':
	    device = optarg;
	    break;
	case 'f':
	    foreground = 1;
	    break;
	    //case 'p':
	    //op.gp_pin = atoi(optarg);
	    //break;
	case 't':
	    opt_ms = atoi(optarg);
	    break;
	    //case 'I':
	    //initial = atoi(optarg);
	    //break;
	case 'B':
	    pid_base = optarg;
	case 'P':
	    opt_pidfile = 1;
	    break;
	case 'n':
	    gpio_ioctl = my_ioctl;
	    break;
	case 'r':
	    led_on_val = GPIO_PIN_LOW;
	    led_off_val = GPIO_PIN_HIGH;
	    break;
	default:
	    usage(device, opt_ms);
	}
    }

    if (argc > optind)
	usage(device, opt_ms);

    if ((gpio_ioctl == ioctl) && (devfd = open(device, O_RDWR)) < 0)
	err(EX_IOERR, "%s", device);

    if (!foreground)
	daemon(1, 0);

    if (opt_pidfile)
	pidfile(pid_base);

    signal(SIGQUIT, bye);
    signal(SIGHUP, bye);
    signal(SIGTERM, bye);

    while(1) {
              
      
    }

    if (devfd > -1)
	close(devfd);

    exit(EX_IOERR);
}