[sim] Add support for disabling SimDevices (#2568)

This allows disabling/enabling SimDevices via prefix matching.  This can be
used to force devices that normally use SimDevice in simulation mode to
instead talk directly to the hardware as in normal operation.

hal/src/main/native/sim/mockdata/SimDeviceData.cpp

@@ -49,12 +49,43 @@ SimDeviceData::Value* SimDeviceData::LookupValue(HAL_SimValueHandle handle) {
   return deviceImpl->values[handle].get();
 }
 
+void SimDeviceData::SetDeviceEnabled(const char* prefix, bool enabled) {
+  std::scoped_lock lock(m_mutex);
+  auto it =
+      std::find_if(m_prefixEnabled.begin(), m_prefixEnabled.end(),
+                   [=](const auto& elem) { return elem.first == prefix; });
+  if (it != m_prefixEnabled.end()) {
+    it->second = enabled;
+    return;
+  }
+  m_prefixEnabled.emplace_back(prefix, enabled);
+  // keep it sorted by name
+  // string comparison sorts shorter before longer, so reverse the sort
+  std::sort(m_prefixEnabled.begin(), m_prefixEnabled.end(),
+            [](const auto& l, const auto& r) { return l.first >= r.first; });
+}
+
+bool SimDeviceData::IsDeviceEnabled(const char* name) {
+  std::scoped_lock lock(m_mutex);
+  for (const auto& elem : m_prefixEnabled) {
+    if (wpi::StringRef{name}.startswith(elem.first)) return elem.second;
+  }
+  return true;
+}
+
 HAL_SimDeviceHandle SimDeviceData::CreateDevice(const char* name) {
   std::scoped_lock lock(m_mutex);
 
+  // don't create if disabled
+  for (const auto& elem : m_prefixEnabled) {
+    if (wpi::StringRef{name}.startswith(elem.first)) {
+      if (elem.second) break;  // enabled
+      return 0;                // disabled
+    }
+  }
+
   // check for duplicates and don't overwrite them
-  auto it = m_deviceMap.find(name);
-  if (it != m_deviceMap.end()) return 0;
+  if (m_deviceMap.count(name) > 0) return 0;
 
   // don't allow more than 4096 devices (limit driven by 12-bit allocation in
   // value changed callback uid)
@@ -326,12 +357,21 @@ void SimDeviceData::ResetData() {
   std::scoped_lock lock(m_mutex);
   m_devices.clear();
   m_deviceMap.clear();
+  m_prefixEnabled.clear();
   m_deviceCreated.Reset();
   m_deviceFreed.Reset();
 }
 
 extern "C" {
 
+void HALSIM_SetSimDeviceEnabled(const char* prefix, HAL_Bool enabled) {
+  SimSimDeviceData->SetDeviceEnabled(prefix, enabled);
+}
+
+HAL_Bool HALSIM_IsSimDeviceEnabled(const char* name) {
+  return SimSimDeviceData->IsDeviceEnabled(name);
+}
+
 int32_t HALSIM_RegisterSimDeviceCreatedCallback(
     const char* prefix, void* param, HALSIM_SimDeviceCallback callback,
     HAL_Bool initialNotify) {