libcamera: pipeline_handler: Return unique_ptr from generateConfiguration()

The PipelineHandler::generateConfiguration() function allocates a
CameraConfiguration instance and returns it. The ownership of the
instance is transferred to the caller. This is a perfect match for a
std::unique_ptr<>, which the Camera::generateConfiguration() function
already returns. Update PipelineHandler::generateConfiguration() to
match it. This fixes a memory leak in one of the error return paths in
the IPU3 pipeline handler.

While at it, update the Camera::generateConfiguration() function
documentation to drop the sentence that describes the ownership
transfer, as that is implied by usage of std::unique_ptr<>.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/camera.cpp

@@ -934,8 +934,7 @@ const std::set<Stream *> &Camera::streams() const
  * \context This function is \threadsafe.
  *
  * \return A CameraConfiguration if the requested roles can be satisfied, or a
- * null pointer otherwise. The ownership of the returned configuration is
- * passed to the caller.
+ * null pointer otherwise.
  */
 std::unique_ptr<CameraConfiguration> Camera::generateConfiguration(const StreamRoles &roles)
 {
@@ -949,7 +948,8 @@ std::unique_ptr<CameraConfiguration> Camera::generateConfiguration(const StreamR
 	if (roles.size() > streams().size())
 		return nullptr;
 
-	CameraConfiguration *config = d->pipe_->generateConfiguration(this, roles);
+	std::unique_ptr<CameraConfiguration> config =
+		d->pipe_->generateConfiguration(this, roles);
 	if (!config) {
 		LOG(Camera, Debug)
 			<< "Pipeline handler failed to generate configuration";
@@ -966,7 +966,7 @@ std::unique_ptr<CameraConfiguration> Camera::generateConfiguration(const StreamR
 
 	LOG(Camera, Debug) << msg.str();
 
-	return std::unique_ptr<CameraConfiguration>(config);
+	return config;
 }
 
 /**