From de26095c582b1c49063fe16ad041eda0afb356b1 Mon Sep 17 00:00:00 2001
From: Thomas Watson <twatson52@icloud.com>
Date: Thu, 23 Nov 2023 21:00:39 -0600
Subject: [PATCH] AP_CANManager: use get_HAL_mutable() to install new CAN
 interfaces

Avoids dubious const_casting.
---
 libraries/AP_CANManager/AP_CANManager.cpp | 30 ++++++++++++++---------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/libraries/AP_CANManager/AP_CANManager.cpp b/libraries/AP_CANManager/AP_CANManager.cpp
index 78be64a97c..9275ea2ba0 100644
--- a/libraries/AP_CANManager/AP_CANManager.cpp
+++ b/libraries/AP_CANManager/AP_CANManager.cpp
@@ -119,6 +119,9 @@ void AP_CANManager::init()
 {
     WITH_SEMAPHORE(_sem);
 
+    // we need to mutate the HAL to install new CAN interfaces
+    AP_HAL::HAL& hal_mutable = AP_HAL::get_HAL_mutable();
+
 #if CONFIG_HAL_BOARD == HAL_BOARD_SITL
     if (AP::sitl() == nullptr) {
         AP_HAL::panic("CANManager: SITL not initialised!");
@@ -146,17 +149,17 @@ void AP_CANManager::init()
         }
         drv_num--;
 
-        if (hal.can[i] == nullptr) {
+        if (hal_mutable.can[i] == nullptr) {
             // So if this interface is not allocated allocate it here,
             // also pass the index of the CANBus
-            const_cast <AP_HAL::HAL&> (hal).can[i] = new HAL_CANIface(i);
+            hal_mutable.can[i] = new HAL_CANIface(i);
         }
 
         // Initialise the interface we just allocated
-        if (hal.can[i] == nullptr) {
+        if (hal_mutable.can[i] == nullptr) {
             continue;
         }
-        AP_HAL::CANIface* iface = hal.can[i];
+        AP_HAL::CANIface* iface = hal_mutable.can[i];
 
         // Find the driver type that we need to allocate and register this interface with
         drv_type[drv_num] = (AP_CAN::Protocol) _drv_param[drv_num]._driver_type.get();
@@ -166,13 +169,13 @@ void AP_CANManager::init()
 #if AP_CAN_SLCAN_ENABLED
         if (_slcan_interface.init_passthrough(i)) {
             // we have slcan bridge setup pass that on as can iface
-            can_initialised = hal.can[i]->init(_interfaces[i]._bitrate, _interfaces[i]._fdbitrate*1000000, AP_HAL::CANIface::NormalMode);
+            can_initialised = hal_mutable.can[i]->init(_interfaces[i]._bitrate, _interfaces[i]._fdbitrate*1000000, AP_HAL::CANIface::NormalMode);
             iface = &_slcan_interface;
         } else {
 #else
         if (true) {
 #endif
-            can_initialised = hal.can[i]->init(_interfaces[i]._bitrate, _interfaces[i]._fdbitrate*1000000, AP_HAL::CANIface::NormalMode);
+            can_initialised = hal_mutable.can[i]->init(_interfaces[i]._bitrate, _interfaces[i]._fdbitrate*1000000, AP_HAL::CANIface::NormalMode);
         }
 
         if (!can_initialised) {
@@ -245,8 +248,8 @@ void AP_CANManager::init()
         bool enable_filter = false;
         for (uint8_t i = 0; i < HAL_NUM_CAN_IFACES; i++) {
             if (_interfaces[i]._driver_number == (drv_num+1) &&
-                hal.can[i] != nullptr &&
-                hal.can[i]->get_operating_mode() == AP_HAL::CANIface::FilteredMode) {
+                hal_mutable.can[i] != nullptr &&
+                hal_mutable.can[i]->get_operating_mode() == AP_HAL::CANIface::FilteredMode) {
                 // Don't worry we don't enable Filters for Normal Ifaces under the driver
                 // this is just to ensure we enable them for the ones we already decided on
                 enable_filter = true;
@@ -284,6 +287,9 @@ bool AP_CANManager::register_driver(AP_CAN::Protocol dtype, AP_CANDriver *driver
 {
     WITH_SEMAPHORE(_sem);
 
+    // we need to mutate the HAL to install new CAN interfaces
+    AP_HAL::HAL& hal_mutable = AP_HAL::get_HAL_mutable();
+
     for (uint8_t i = 0; i < HAL_NUM_CAN_IFACES; i++) {
         uint8_t drv_num = _interfaces[i]._driver_number;
         if (drv_num == 0 || drv_num > HAL_MAX_CAN_PROTOCOL_DRIVERS) {
@@ -302,17 +308,17 @@ bool AP_CANManager::register_driver(AP_CAN::Protocol dtype, AP_CANDriver *driver
             continue;
         }
 
-        if (hal.can[i] == nullptr) {
+        if (hal_mutable.can[i] == nullptr) {
             // if this interface is not allocated allocate it here,
             // also pass the index of the CANBus
-            const_cast <AP_HAL::HAL&> (hal).can[i] = new HAL_CANIface(i);
+            hal_mutable.can[i] = new HAL_CANIface(i);
         }
 
         // Initialise the interface we just allocated
-        if (hal.can[i] == nullptr) {
+        if (hal_mutable.can[i] == nullptr) {
             continue;
         }
-        AP_HAL::CANIface* iface = hal.can[i];
+        AP_HAL::CANIface* iface = hal_mutable.can[i];
 
         _drivers[drv_num] = driver;
         _drivers[drv_num]->add_interface(iface);