libcamera: pipeline_handler: Return unique_ptr from createInstance

Avoid naked pointer with memory allocation by returning a unique_ptr
from PipelineHandlerFactory::createInstance(), in order to increase
memory allocation safety.

This allows iterating over factories in the CameraManager and unit tests
using const pointers.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Xavier Roumegue <xavier.roumegue@oss.nxp.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

include/libcamera/internal/pipeline_handler.h

@@ -113,7 +113,8 @@ public:
 private:
 	static void registerType(PipelineHandlerFactory *factory);
 
-	virtual PipelineHandler *createInstance(CameraManager *manager) const = 0;
+	virtual std::unique_ptr<PipelineHandler>
+	createInstance(CameraManager *manager) const = 0;
 
 	std::string name_;
 };
@@ -125,9 +126,10 @@ public:									\
 	handler##Factory() : PipelineHandlerFactory(#handler) {}	\
 									\
 private:								\
-	PipelineHandler *createInstance(CameraManager *manager) const	\
+	std::unique_ptr<PipelineHandler>				\
+	createInstance(CameraManager *manager) const			\
 	{								\
-		return new handler(manager);				\
+		return std::make_unique<handler>(manager);		\
 	}								\
 };									\
 static handler##Factory global_##handler##Factory;

src/libcamera/camera_manager.cpp

@@ -142,10 +142,10 @@ void CameraManager::Private::createPipelineHandlers()
 	 * file and only fallback on all handlers if there is no
 	 * configuration file.
 	 */
-	std::vector<PipelineHandlerFactory *> &factories =
+	const std::vector<PipelineHandlerFactory *> &factories =
 		PipelineHandlerFactory::factories();
 
-	for (PipelineHandlerFactory *factory : factories) {
+	for (const PipelineHandlerFactory *factory : factories) {
 		LOG(Camera, Debug)
 			<< "Found registered pipeline handler '"
 			<< factory->name() << "'";

src/libcamera/pipeline_handler.cpp

@@ -678,9 +678,9 @@ PipelineHandlerFactory::PipelineHandlerFactory(const char *name)
  */
 std::shared_ptr<PipelineHandler> PipelineHandlerFactory::create(CameraManager *manager) const
 {
-	PipelineHandler *handler = createInstance(manager);
+	std::unique_ptr<PipelineHandler> handler = createInstance(manager);
 	handler->name_ = name_.c_str();
-	return std::shared_ptr<PipelineHandler>(handler);
+	return std::shared_ptr<PipelineHandler>(std::move(handler));
 }
 
 /**
@@ -727,8 +727,8 @@ std::vector<PipelineHandlerFactory *> &PipelineHandlerFactory::factories()
  * macro. It creates a pipeline handler instance associated with the camera
  * \a manager.
  *
- * \return a pointer to a newly constructed instance of the PipelineHandler
+ * \return A unique pointer to a newly constructed instance of the
- * subclass corresponding to the factory
+ * PipelineHandler subclass corresponding to the factory
  */
 
 /**

test/ipa/ipa_interface_test.cpp

@@ -52,9 +52,9 @@ protected:
 		ipaManager_ = make_unique<IPAManager>();
 
 		/* Create a pipeline handler for vimc. */
-		std::vector<PipelineHandlerFactory *> &factories =
+		const std::vector<PipelineHandlerFactory *> &factories =
 			PipelineHandlerFactory::factories();
-		for (PipelineHandlerFactory *factory : factories) {
+		for (const PipelineHandlerFactory *factory : factories) {
 			if (factory->name() == "PipelineHandlerVimc") {
 				pipe_ = factory->create(nullptr);
 				break;