Check period duration in create_wall_timer (#1178)

* Check period duration in create_wall_timer

Signed-off-by: Stephen Brawner <brawner@gmail.com>

* Adding comments

Signed-off-by: Stephen Brawner <brawner@gmail.com>

rclcpp/include/rclcpp/create_timer.hpp

@@ -76,14 +76,14 @@ create_timer(
  * \tparam DurationRepT
  * \tparam DurationT
  * \tparam CallbackT
- * \param period period to exectute callback
+ * \param period period to execute callback. This duration must be 0 <= period < nanoseconds::max()
  * \param callback callback to execute via the timer period
  * \param group
  * \param node_base
  * \param node_timers
  * \return
  * \throws std::invalid argument if either node_base or node_timers
- * are null
+ * are null, or period is negative or too large
  */
 template<typename DurationRepT, typename DurationT, typename CallbackT>
 typename rclcpp::WallTimer<CallbackT>::SharedPtr
@@ -102,10 +102,38 @@ create_wall_timer(
     throw std::invalid_argument{"input node_timers cannot be null"};
   }
 
+  if (period < std::chrono::duration<DurationRepT, DurationT>::zero()) {
+    throw std::invalid_argument{"timer period cannot be negative"};
+  }
+
+  // Casting to a double representation might lose precision and allow the check below to succeed
+  // but the actual cast to nanoseconds fail. Using 1 DurationT worth of nanoseconds less than max.
+  constexpr auto maximum_safe_cast_ns =
+    std::chrono::nanoseconds::max() - std::chrono::duration<DurationRepT, DurationT>(1);
+
+  // If period is greater than nanoseconds::max(), the duration_cast to nanoseconds will overflow
+  // a signed integer, which is undefined behavior. Checking whether any std::chrono::duration is
+  // greater than nanoseconds::max() is a difficult general problem. This is a more conservative
+  // version of Howard Hinnant's (the <chrono> guy>) response here:
+  // https://stackoverflow.com/a/44637334/2089061
+  // However, this doesn't solve the issue for all possible duration types of period.
+  // Follow-up issue: https://github.com/ros2/rclcpp/issues/1177
+  constexpr auto ns_max_as_double =
+    std::chrono::duration_cast<std::chrono::duration<double, std::chrono::nanoseconds::period>>(
+    maximum_safe_cast_ns);
+  if (period > ns_max_as_double) {
+    throw std::invalid_argument{
+            "timer period must be less than std::chrono::nanoseconds::max()"};
+  }
+
+  const auto period_ns = std::chrono::duration_cast<std::chrono::nanoseconds>(period);
+  if (period_ns < std::chrono::nanoseconds::zero()) {
+    throw std::runtime_error{
+            "Casting timer period to nanoseconds resulted in integer overflow."};
+  }
+
   auto timer = rclcpp::WallTimer<CallbackT>::make_shared(
-    std::chrono::duration_cast<std::chrono::nanoseconds>(period),
-    std::move(callback),
-    node_base->get_context());
+    period_ns, std::move(callback), node_base->get_context());
   node_timers->add_timer(timer, group);
   return timer;
 }

rclcpp/test/rclcpp/test_create_timer.cpp

@@ -18,10 +18,10 @@
 #include <chrono>
 #include <memory>
 
+#include "node_interfaces/node_wrapper.hpp"
 #include "rclcpp/create_timer.hpp"
 #include "rclcpp/executors.hpp"
 #include "rclcpp/node.hpp"
-#include "node_interfaces/node_wrapper.hpp"
 
 using namespace std::chrono_literals;
 
@@ -61,3 +61,58 @@ TEST(TestCreateTimer, call_with_node_wrapper_compiles)
     []() {});
   rclcpp::shutdown();
 }
+
+TEST(TestCreateTimer, call_wall_timer_with_bad_arguments)
+{
+  rclcpp::init(0, nullptr);
+  NodeWrapper node("test_create_wall_timers_with_bad_arguments");
+  auto callback = []() {};
+  rclcpp::CallbackGroup::SharedPtr group = nullptr;
+  auto node_interface =
+    rclcpp::node_interfaces::get_node_base_interface(node).get();
+  auto timers_interface =
+    rclcpp::node_interfaces::get_node_timers_interface(node).get();
+
+  // Negative period
+  EXPECT_THROW(
+    rclcpp::create_wall_timer(-1ms, callback, group, node_interface, timers_interface),
+    std::invalid_argument);
+
+  // Very negative period
+  constexpr auto nanoseconds_min = std::chrono::nanoseconds::min();
+  EXPECT_THROW(
+    rclcpp::create_wall_timer(
+      nanoseconds_min, callback, group, node_interface, timers_interface),
+    std::invalid_argument);
+
+  // Period must be less than nanoseconds::max()
+  constexpr auto nanoseconds_max = std::chrono::nanoseconds::min();
+  EXPECT_THROW(
+    rclcpp::create_wall_timer(
+      nanoseconds_max, callback, group, node_interface, timers_interface),
+    std::invalid_argument);
+
+  EXPECT_NO_THROW(
+    rclcpp::create_wall_timer(
+      nanoseconds_max - 1us, callback, group, node_interface, timers_interface));
+
+  EXPECT_NO_THROW(
+    rclcpp::create_wall_timer(0ms, callback, group, node_interface, timers_interface));
+
+  // Period must be less than nanoseconds::max()
+  constexpr auto hours_max = std::chrono::hours::max();
+  EXPECT_THROW(
+    rclcpp::create_wall_timer(hours_max, callback, group, node_interface, timers_interface),
+    std::invalid_argument);
+
+  // node_interface is null
+  EXPECT_THROW(
+    rclcpp::create_wall_timer(1ms, callback, group, nullptr, timers_interface),
+    std::invalid_argument);
+
+  // timers_interface is null
+  EXPECT_THROW(
+    rclcpp::create_wall_timer(1ms, callback, group, node_interface, nullptr),
+    std::invalid_argument);
+  rclcpp::shutdown();
+}