introduce ROS_DISABLE_LOAN_MSG to disable can_loan_messages.

rcl/include/rcl/node.h

@@ -33,6 +33,8 @@ extern "C"
 #include "rcl/types.h"
 #include "rcl/visibility_control.h"
 
+extern const char * const RCL_DISABLE_LOANED_MESSAGES_ENV_VAR;
+
 typedef struct rcl_node_impl_s rcl_node_impl_t;
 
 /// Structure which encapsulates a ROS Node.
@@ -533,6 +535,20 @@ rcl_node_resolve_name(
   bool only_expand,
   char ** output_name);
 
+/// Check if loaned message is disabled, according to the environment variable.
+/**
+ * If the `ROS_DISABLE_LOANED_MESSAGES` environment variable is set to "1",
+ * `disable_loaned_message` will be set to true.
+ *
+ * \param[out] disable_loaned_message Must not be NULL.
+ * \return #RCL_RET_INVALID_ARGUMENT if an argument is not valid, or
+ * \return #RCL_RET_ERROR if an unexpected error happened, or
+ * \return #RCL_RET_OK.
+ */
+RCL_PUBLIC
+rcl_ret_t
+rcl_get_disable_loaned_message(bool * disable_loaned_message);
+
 #ifdef __cplusplus
 }
 #endif

rcl/src/rcl/node.c

@@ -34,6 +34,7 @@ extern "C"
 #include "rcl/remap.h"
 #include "rcl/security.h"
 
+#include "rcutils/env.h"
 #include "rcutils/filesystem.h"
 #include "rcutils/find.h"
 #include "rcutils/format_string.h"
@@ -52,6 +53,8 @@ extern "C"
 
 #include "./context_impl.h"
 
+const char * const RCL_DISABLE_LOANED_MESSAGES_ENV_VAR = "ROS_DISABLE_LOANED_MESSAGES";
+
 struct rcl_node_impl_s
 {
   rcl_node_options_t options;
@@ -514,6 +517,25 @@ rcl_node_get_logger_name(const rcl_node_t * node)
   return node->impl->logger_name;
 }
 
+rcl_ret_t
+rcl_get_disable_loaned_message(bool * disable_loaned_message)
+{
+  const char * env_val = NULL;
+  const char * env_error_str = NULL;
+
+  RCL_CHECK_ARGUMENT_FOR_NULL(disable_loaned_message, RCL_RET_INVALID_ARGUMENT);
+
+  env_error_str = rcutils_get_env(RCL_DISABLE_LOANED_MESSAGES_ENV_VAR, &env_val);
+  if (NULL != env_error_str) {
+    RCL_SET_ERROR_MSG_WITH_FORMAT_STRING(
+      "Error getting env var: '" RCUTILS_STRINGIFY(RCL_DISABLE_LOANED_MESSAGES_ENV_VAR) "': %s\n",
+      env_error_str);
+    return RCL_RET_ERROR;
+  }
+
+  *disable_loaned_message = (strcmp(env_val, "1") == 0);
+  return RCL_RET_OK;
+}
 #ifdef __cplusplus
 }
 #endif

rcl/src/rcl/publisher.c

@@ -440,6 +440,13 @@ rcl_publisher_can_loan_messages(const rcl_publisher_t * publisher)
   if (!rcl_publisher_is_valid(publisher)) {
     return false;  // error message already set
   }
+
+  bool disable_loaned_message = false;
+  rcl_ret_t ret = rcl_get_disable_loaned_message(&disable_loaned_message);
+  if (ret == RCL_RET_OK && disable_loaned_message) {
+    return false;
+  }
+
   return publisher->impl->rmw_handle->can_loan_messages;
 }
 

rcl/src/rcl/subscription.c

@@ -435,6 +435,13 @@ rcl_subscription_can_loan_messages(const rcl_subscription_t * subscription)
   if (!rcl_subscription_is_valid(subscription)) {
     return false;  // error message already set
   }
+
+  bool disable_loaned_message = false;
+  rcl_ret_t ret = rcl_get_disable_loaned_message(&disable_loaned_message);
+  if (ret == RCL_RET_OK && disable_loaned_message) {
+    return false;
+  }
+
   return subscription->impl->rmw_handle->can_loan_messages;
 }
 

rcl/test/rcl/test_node.cpp

@@ -27,6 +27,7 @@
 #include "./failing_allocator_functions.hpp"
 #include "osrf_testing_tools_cpp/memory_tools/memory_tools.hpp"
 #include "osrf_testing_tools_cpp/scope_exit.hpp"
+#include "rcutils/env.h"
 #include "rcutils/testing/fault_injection.h"
 #include "rcl/error_handling.h"
 #include "rcl/logging.h"
@@ -997,3 +998,48 @@ TEST_F(CLASSNAME(TestNodeFixture, RMW_IMPLEMENTATION), test_rcl_node_resolve_nam
   EXPECT_STREQ("/ns/relative_ns/foo", final_name);
   default_allocator.deallocate(final_name, default_allocator.state);
 }
+
+/* Tests special case node_options
+ */
+TEST_F(CLASSNAME(TestNodeFixture, RMW_IMPLEMENTATION), test_rcl_get_disable_loaned_message) {
+  {
+    EXPECT_EQ(RCL_RET_INVALID_ARGUMENT, rcl_get_disable_loaned_message(nullptr));
+    rcl_reset_error();
+  }
+
+  {
+    bool disable_loaned_message = false;
+    auto mock = mocking_utils::patch_and_return(
+      "lib:rcl", rcutils_get_env, "internal error");
+    EXPECT_EQ(RCL_RET_ERROR, rcl_get_disable_loaned_message(&disable_loaned_message));
+    rcl_reset_error();
+  }
+
+  {
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "0"));
+    bool disable_loaned_message = true;
+    EXPECT_EQ(RCL_RET_OK, rcl_get_disable_loaned_message(&disable_loaned_message));
+    EXPECT_FALSE(disable_loaned_message);
+  }
+
+  {
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "1"));
+    bool disable_loaned_message = false;
+    EXPECT_EQ(RCL_RET_OK, rcl_get_disable_loaned_message(&disable_loaned_message));
+    EXPECT_TRUE(disable_loaned_message);
+  }
+
+  {
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "2"));
+    bool disable_loaned_message = true;
+    EXPECT_EQ(RCL_RET_OK, rcl_get_disable_loaned_message(&disable_loaned_message));
+    EXPECT_FALSE(disable_loaned_message);
+  }
+
+  {
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "11"));
+    bool disable_loaned_message = true;
+    EXPECT_EQ(RCL_RET_OK, rcl_get_disable_loaned_message(&disable_loaned_message));
+    EXPECT_FALSE(disable_loaned_message);
+  }
+}

rcl/test/rcl/test_publisher.cpp

@@ -24,6 +24,8 @@
 #include "mimick/mimick.h"
 #include "osrf_testing_tools_cpp/scope_exit.hpp"
 #include "rcl/error_handling.h"
+#include "rcl/node.h"
+#include "rcutils/env.h"
 #include "rmw/validate_full_topic_name.h"
 #include "rmw/validate_node_name.h"
 
@@ -370,6 +372,42 @@ TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_publisher_loan)
   }
 }
 
+TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_publisher_loan_disable) {
+  rcl_publisher_t publisher = rcl_get_zero_initialized_publisher();
+  const rosidl_message_type_support_t * ts =
+    ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, BasicTypes);
+  constexpr char topic_name[] = "pod_msg";
+  rcl_publisher_options_t publisher_options = rcl_publisher_get_default_options();
+  rcl_ret_t ret =
+    rcl_publisher_init(&publisher, this->node_ptr, ts, topic_name, &publisher_options);
+  ASSERT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+  OSRF_TESTING_TOOLS_CPP_SCOPE_EXIT(
+  {
+    rcl_ret_t ret = rcl_publisher_fini(&publisher, this->node_ptr);
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+  });
+
+  if (rcl_publisher_can_loan_messages(&publisher)) {
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "0"));
+    EXPECT_TRUE(rcl_publisher_can_loan_messages(&publisher));
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "1"));
+    EXPECT_FALSE(rcl_publisher_can_loan_messages(&publisher));
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "2"));
+    EXPECT_TRUE(rcl_publisher_can_loan_messages(&publisher));
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "Unexpected"));
+    EXPECT_TRUE(rcl_publisher_can_loan_messages(&publisher));
+  } else {
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "0"));
+    EXPECT_FALSE(rcl_publisher_can_loan_messages(&publisher));
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "1"));
+    EXPECT_FALSE(rcl_publisher_can_loan_messages(&publisher));
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "2"));
+    EXPECT_FALSE(rcl_publisher_can_loan_messages(&publisher));
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "Unexpected"));
+    EXPECT_FALSE(rcl_publisher_can_loan_messages(&publisher));
+  }
+}
+
 TEST_F(CLASSNAME(TestPublisherFixture, RMW_IMPLEMENTATION), test_invalid_publisher) {
   rcl_publisher_t publisher = rcl_get_zero_initialized_publisher();
   const rosidl_message_type_support_t * ts =

rcl/test/rcl/test_subscription.cpp

@@ -30,6 +30,8 @@
 
 #include "osrf_testing_tools_cpp/scope_exit.hpp"
 #include "rcl/error_handling.h"
+#include "rcl/node.h"
+#include "rcutils/env.h"
 #include "wait_for_entity_helpers.hpp"
 
 #include "./allocator_testing_utils.h"
@@ -712,6 +714,42 @@ TEST_F(CLASSNAME(TestSubscriptionFixture, RMW_IMPLEMENTATION), test_subscription
   }
 }
 
+TEST_F(CLASSNAME(TestSubscriptionFixture, RMW_IMPLEMENTATION), test_subscription_loan_disable) {
+  rcl_subscription_t subscription = rcl_get_zero_initialized_subscription();
+  const rosidl_message_type_support_t * ts =
+    ROSIDL_GET_MSG_TYPE_SUPPORT(test_msgs, msg, BasicTypes);
+  constexpr char topic[] = "pod_msg";
+  rcl_subscription_options_t subscription_options = rcl_subscription_get_default_options();
+  rcl_ret_t ret =
+    rcl_subscription_init(&subscription, this->node_ptr, ts, topic, &subscription_options);
+  ASSERT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+  OSRF_TESTING_TOOLS_CPP_SCOPE_EXIT(
+  {
+    rcl_ret_t ret = rcl_subscription_fini(&subscription, this->node_ptr);
+    EXPECT_EQ(RCL_RET_OK, ret) << rcl_get_error_string().str;
+  });
+
+  if (rcl_subscription_can_loan_messages(&subscription)) {
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "0"));
+    EXPECT_TRUE(rcl_subscription_can_loan_messages(&subscription));
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "1"));
+    EXPECT_FALSE(rcl_subscription_can_loan_messages(&subscription));
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "2"));
+    EXPECT_TRUE(rcl_subscription_can_loan_messages(&subscription));
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "Unexpected"));
+    EXPECT_TRUE(rcl_subscription_can_loan_messages(&subscription));
+  } else {
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "0"));
+    EXPECT_FALSE(rcl_subscription_can_loan_messages(&subscription));
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "1"));
+    EXPECT_FALSE(rcl_subscription_can_loan_messages(&subscription));
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "2"));
+    EXPECT_FALSE(rcl_subscription_can_loan_messages(&subscription));
+    ASSERT_TRUE(rcutils_set_env("ROS_DISABLE_LOANED_MESSAGES", "Unexpected"));
+    EXPECT_FALSE(rcl_subscription_can_loan_messages(&subscription));
+  }
+}
+
 /* Test for all failure modes in subscription take with loaned messages function.
  */
 TEST_F(CLASSNAME(TestSubscriptionFixture, RMW_IMPLEMENTATION), test_bad_take_loaned_message) {