zhangyang-variable-monitor/source/uapi/monitor_user.c

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

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

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

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

void init_watch_arg(watch_arg *wg, char *name, void *ptr,
                           int length_byte, long long threshold,
                           unsigned char unsigned_flag,
                           unsigned char above_threshold, unsigned long time_ns){
  wg->task_id = getpid();
  strncpy(wg->name, name, (MAX_NAME_LEN + 1));
  wg->ptr = ptr;
  wg->length_byte = length_byte;
  wg->threshold = threshold;
  wg->unsigned_flag = unsigned_flag;
  wg->above_threshold = above_threshold;
  wg->time_ns = time_ns;
}