adjust

source/uapi/monitor_user.c

@@ -0,0 +1,44 @@
+#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, 1, &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;
+}