#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/wait.h>

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define RFCOMMCREATEDEV		_IOW('R', 200, int)
#define RFCOMMRELEASEDEV	_IOW('R', 201, int)
#define BTPROTO_RFCOMM  3

typedef uint8_t u8;
typedef uint32_t u32;
typedef int16_t s16;
typedef uint8_t __u8;

/* BD Address */
typedef struct {
	__u8 b[6];
} __attribute__((packed)) bdaddr_t;

struct rfcomm_dev_req {
	s16      dev_id;
	u32      flags;
	bdaddr_t src;
	bdaddr_t dst;
	u8       channel;
};

void rfcomm(int request, int dev_id)
{
	int fd = socket(PF_BLUETOOTH, SOCK_STREAM, BTPROTO_RFCOMM);
	if (fd == -1) {
		fprintf(stderr, "socket: error: %s\n", strerror(errno));
		exit(EXIT_FAILURE);
	}

	struct rfcomm_dev_req req;
	memset(&req, 0, sizeof(req));
	req.dev_id = dev_id;
	req.channel = 1;

	if (ioctl(fd, request, &req) == -1) {
		fprintf(stderr, "ioctl: error: %s\n", strerror(errno));
		exit(EXIT_FAILURE);
	}

	while (close(fd) == -1 && errno == EINTR);
}

int
main(int argc, char *argv[])
{
	pid_t child;

	child = fork();
	if (child == -1) {
		fprintf(stderr, "fork: error: %s\n", strerror(errno));
		exit(EXIT_FAILURE);
	}

	if (child == 0) {
		printf("Creating\n");
		rfcomm(RFCOMMCREATEDEV, 0);

		printf("Opening /dev/rfcomm0...\n");

		int fd = open("/dev/rfcomm0", O_RDWR | O_NOCTTY);
		if (fd == -1) {
			fprintf(stderr, "open: error: %s\n", strerror(errno));
			rfcomm(RFCOMMRELEASEDEV, 0);
			exit(EXIT_FAILURE);
		}

		exit(EXIT_SUCCESS);
	}

	sleep(1);

	/* This will delete the device, but since we still hold a reference
	 * to it in "fd", the tty won't be unregistered yet... */
	printf("Releasing\n");
	rfcomm(RFCOMMRELEASEDEV, 0);

	/* And now we try to register the same tty device... */
	printf("Recreating\n");
	rfcomm(RFCOMMCREATEDEV, 0);

	/* Cleanup */
	printf("Releasing\n");
	rfcomm(RFCOMMRELEASEDEV, 0);

	while (1) {
		int status;

		if (wait(&status) == -1) {
			if (errno == ECHILD)
				break;

			fprintf(stderr, "wait: error: %s\n", strerror(errno));
			exit(EXIT_FAILURE);
		}
	}

	return EXIT_SUCCESS;
}