libcamera: base: class: Don't pass Extensible pointer to Private constructor

The Extensible and Extensible::Private classes contain pointers to each
other. These pointers are initialized in the respective class's
constructor, by passing a pointer to the other class to each
constructor. This particular construct reduces the flexibility of the
Extensible pattern, as the Private class instance has to be allocated
and constructed in the members initializer list of the Extensible
class's constructor. It is thus impossible to perform any operation on
the Private class between its construction and the construction of the
Extensible class, or to subclass the Private class without subclassing
the Extensible class.

To make the design pattern more flexible, don't pass the pointer to the
Extensible class to the Private class's constructor, but initialize the
pointer manually in the Extensible class's constructor. This requires a
const_cast as the o_ member of the Private class is const.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>

include/libcamera/base/class.h

@@ -64,7 +64,7 @@ public:
 	class Private
 	{
 	public:
-		Private(Extensible *o);
+		Private();
 		virtual ~Private();
 
 #ifndef __DOXYGEN__
@@ -82,6 +82,8 @@ public:
 #endif
 
 	private:
+		/* To initialize o_ from Extensible. */
+		friend class Extensible;
 		Extensible *const o_;
 	};
 

include/libcamera/internal/framebuffer.h

@@ -52,7 +52,7 @@ class FrameBuffer::Private : public Extensible::Private
 	LIBCAMERA_DECLARE_PUBLIC(FrameBuffer)
 
 public:
-	Private(FrameBuffer *buffer);
+	Private();
 
 	void setRequest(Request *request) { request_ = request; }
 

src/android/camera_hal_config.cpp

@@ -32,7 +32,7 @@ class CameraHalConfig::Private : public Extensible::Private
 	LIBCAMERA_DECLARE_PUBLIC(CameraHalConfig)
 
 public:
-	Private(CameraHalConfig *halConfig);
+	Private();
 
 	int parseConfigFile(FILE *fh, std::map<std::string, CameraConfigData> *cameras);
 
@@ -50,8 +50,7 @@ private:
 	std::map<std::string, CameraConfigData> *cameras_;
 };
 
-CameraHalConfig::Private::Private(CameraHalConfig *halConfig)
-	: Extensible::Private(halConfig)
+CameraHalConfig::Private::Private()
 {
 }
 
@@ -344,7 +343,7 @@ int CameraHalConfig::Private::parseConfigFile(FILE *fh,
 }
 
 CameraHalConfig::CameraHalConfig()
-	: Extensible(new Private(this)), exists_(false), valid_(false)
+	: Extensible(new Private()), exists_(false), valid_(false)
 {
 	parseConfigurationFile();
 }

src/android/mm/cros_camera_buffer.cpp

@@ -47,8 +47,8 @@ private:
 CameraBuffer::Private::Private(CameraBuffer *cameraBuffer,
 			       buffer_handle_t camera3Buffer,
 			       [[maybe_unused]] int flags)
-	: Extensible::Private(cameraBuffer), handle_(camera3Buffer),
-	  numPlanes_(0), valid_(false), registered_(false)
+	: handle_(camera3Buffer), numPlanes_(0), valid_(false),
+	  registered_(false)
 {
 	bufferManager_ = cros::CameraBufferManager::GetInstance();
 

src/android/mm/generic_camera_buffer.cpp

@@ -34,9 +34,8 @@ public:
 	size_t jpegBufferSize(size_t maxJpegBufferSize) const;
 };
 
-CameraBuffer::Private::Private(CameraBuffer *cameraBuffer,
+CameraBuffer::Private::Private([[maybe_unused]] CameraBuffer *cameraBuffer,
 			       buffer_handle_t camera3Buffer, int flags)
-	: Extensible::Private(cameraBuffer)
 {
 	maps_.reserve(camera3Buffer->numFds);
 	error_ = 0;

src/libcamera/base/class.cpp

@@ -151,6 +151,7 @@ namespace libcamera {
 Extensible::Extensible(Extensible::Private *d)
 	: d_(d)
 {
+	*const_cast<Extensible **>(&d_->o_) = this;
 }
 
 /**
@@ -182,10 +183,9 @@ Extensible::Extensible(Extensible::Private *d)
 
 /**
  * \brief Construct an instance of an Extensible class private data
- * \param[in] o Pointer to the public class object
  */
-Extensible::Private::Private(Extensible *o)
-	: o_(o)
+Extensible::Private::Private()
+	: o_(nullptr)
 {
 }
 

src/libcamera/camera.cpp

@@ -344,7 +344,7 @@ public:
 		CameraRunning,
 	};
 
-	Private(Camera *camera, PipelineHandler *pipe, const std::string &id,
+	Private(PipelineHandler *pipe, const std::string &id,
 		const std::set<Stream *> &streams);
 	~Private();
 
@@ -368,11 +368,11 @@ private:
 	std::atomic<State> state_;
 };
 
-Camera::Private::Private(Camera *camera, PipelineHandler *pipe,
+Camera::Private::Private(PipelineHandler *pipe,
 			 const std::string &id,
 			 const std::set<Stream *> &streams)
-	: Extensible::Private(camera), pipe_(pipe->shared_from_this()), id_(id),
-	  streams_(streams), disconnected_(false), state_(CameraAvailable)
+	: pipe_(pipe->shared_from_this()), id_(id), streams_(streams),
+	  disconnected_(false), state_(CameraAvailable)
 {
 }
 
@@ -632,7 +632,7 @@ const std::string &Camera::id() const
 
 Camera::Camera(PipelineHandler *pipe, const std::string &id,
 	       const std::set<Stream *> &streams)
-	: Extensible(new Private(this, pipe, id, streams))
+	: Extensible(new Private(pipe, id, streams))
 {
 }
 

src/libcamera/camera_manager.cpp

@@ -39,7 +39,7 @@ class CameraManager::Private : public Extensible::Private, public Thread
 	LIBCAMERA_DECLARE_PUBLIC(CameraManager)
 
 public:
-	Private(CameraManager *cm);
+	Private();
 
 	int start();
 	void addCamera(std::shared_ptr<Camera> camera,
@@ -74,8 +74,8 @@ private:
 	ProcessManager processManager_;
 };
 
-CameraManager::Private::Private(CameraManager *cm)
-	: Extensible::Private(cm), initialized_(false)
+CameraManager::Private::Private()
+	: initialized_(false)
 {
 }
 
@@ -258,7 +258,7 @@ void CameraManager::Private::removeCamera(Camera *camera)
 CameraManager *CameraManager::self_ = nullptr;
 
 CameraManager::CameraManager()
-	: Extensible(new CameraManager::Private(this))
+	: Extensible(new CameraManager::Private())
 {
 	if (self_)
 		LOG(Camera, Fatal)

src/libcamera/framebuffer.cpp

@@ -100,8 +100,8 @@ LOG_DEFINE_CATEGORY(Buffer)
  * \brief Array of per-plane metadata
  */
 
-FrameBuffer::Private::Private(FrameBuffer *buffer)
-	: Extensible::Private(buffer), request_(nullptr)
+FrameBuffer::Private::Private()
+	: request_(nullptr)
 {
 }
 
@@ -176,7 +176,7 @@ FrameBuffer::Private::Private(FrameBuffer *buffer)
  * \param[in] cookie Cookie
  */
 FrameBuffer::FrameBuffer(const std::vector<Plane> &planes, unsigned int cookie)
-	: Extensible(new Private(this)), planes_(planes), cookie_(cookie)
+	: Extensible(new Private()), planes_(planes), cookie_(cookie)
 {
 }