// #include "monitor_user.h"
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <unistd.h>

#define DEVICE "/dev/variable_monitor"
int file_desc = -1;

pid_t pid = 0;

/// @brief start watch
/// @param w_arg
/// @return 0 means success, other means fail
int start_watch() {
  if (file_desc < 0) {
    file_desc = open(DEVICE, 0);
  }
  if (file_desc < 0) {
    printf("Can't open device file: %s\n", DEVICE);
    return -1;
  }

  printf("1 \n");

  if (ioctl(file_desc, 2, &pid) < 0) {
    printf("ioctl failed\n");
    close(file_desc);
    return -1;
  }

  printf("2 \n");
  return 0;
}

/// @brief cancel watch
/// @return 0 means success, other means fail
int cancel_watch() {
  if (file_desc < 0) {
    file_desc = open(DEVICE, 0);
  }
  if (file_desc < 0) {
    printf("Device not open: %s,%d \n", DEVICE, file_desc);
    return file_desc;
  }

  close(file_desc);
  file_desc = -1;
  return 0;
}

int main(int argc, char **argv){
    if (argc != 2)
		printf("USAGE: unwind-pid <pid>\n");

	pid = atoi(argv[1]);

    printf("%d \n", pid);

    start_watch();
    cancel_watch();
}