Protect busy VfsObjs during opening and deleting

kernel/hal/util.c

@@ -140,3 +140,13 @@ char *hal_strstr(const char *str, const char *substring)
 
     return NULL;
 }
+
+char *hal_string_combine(char *dest, const char *src) {
+  size_t i, j;
+  for(i = 0; dest[i] != '\0'; i++);
+  for(j = 0; src[j] != '\0'; j++) {
+    dest[i+j] = src[j];
+  }
+  dest[i+j] = '\0';
+  return dest;
+}