libcamera: v4l2_subdevice: Return a unique pointer from fromEntityName()

The fromEntityName() function returns a pointer to a newly allocated
V4L2Subdevice instance, which must be deleted by the caller. This opens
the door to memory leaks. Return a unique pointer instead, which conveys
the API semantics better than a sentence in the documentation.

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

include/libcamera/internal/v4l2_subdevice.h

@@ -7,6 +7,7 @@
 #ifndef __LIBCAMERA_INTERNAL_V4L2_SUBDEVICE_H__
 #define __LIBCAMERA_INTERNAL_V4L2_SUBDEVICE_H__
 
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -60,8 +61,8 @@ public:
 	int setFormat(unsigned int pad, V4L2SubdeviceFormat *format,
 		      Whence whence = ActiveFormat);
 
-	static V4L2Subdevice *fromEntityName(const MediaDevice *media,
-					     const std::string &entity);
+	static std::unique_ptr<V4L2Subdevice>
+	fromEntityName(const MediaDevice *media, const std::string &entity);
 
 protected:
 	std::string logPrefix() const override;

src/libcamera/pipeline/ipu3/imgu.cpp

@@ -343,7 +343,7 @@ int ImgUDevice::init(MediaDevice *media, unsigned int index)
 	 * by the match() function: no need to check for newly created
 	 * video devices and subdevice validity here.
 	 */
-	imgu_.reset(V4L2Subdevice::fromEntityName(media, name_));
+	imgu_ = V4L2Subdevice::fromEntityName(media, name_);
 	ret = imgu_->open();
 	if (ret)
 		return ret;

src/libcamera/pipeline/rkisp1/rkisp1.cpp

@@ -217,7 +217,7 @@ private:
 	int freeBuffers(Camera *camera);
 
 	MediaDevice *media_;
-	V4L2Subdevice *isp_;
+	std::unique_ptr<V4L2Subdevice> isp_;
 	V4L2VideoDevice *param_;
 	V4L2VideoDevice *stat_;
 
@@ -599,8 +599,7 @@ CameraConfiguration::Status RkISP1CameraConfiguration::validate()
 }
 
 PipelineHandlerRkISP1::PipelineHandlerRkISP1(CameraManager *manager)
-	: PipelineHandler(manager), isp_(nullptr), param_(nullptr),
-	  stat_(nullptr)
+	: PipelineHandler(manager), param_(nullptr), stat_(nullptr)
 {
 }
 
@@ -608,7 +607,6 @@ PipelineHandlerRkISP1::~PipelineHandlerRkISP1()
 {
 	delete param_;
 	delete stat_;
-	delete isp_;
 }
 
 /* -----------------------------------------------------------------------------

src/libcamera/pipeline/rkisp1/rkisp1_path.cpp

@@ -24,14 +24,13 @@ RkISP1Path::RkISP1Path(const char *name, const Span<const PixelFormat> &formats,
 		       const Size &minResolution, const Size &maxResolution)
 	: name_(name), running_(false), formats_(formats),
 	  minResolution_(minResolution), maxResolution_(maxResolution),
-	  resizer_(nullptr), video_(nullptr), link_(nullptr)
+	  video_(nullptr), link_(nullptr)
 {
 }
 
 RkISP1Path::~RkISP1Path()
 {
 	delete video_;
-	delete resizer_;
 }
 
 bool RkISP1Path::init(MediaDevice *media)

src/libcamera/pipeline/rkisp1/rkisp1_path.h

@@ -7,6 +7,7 @@
 #ifndef __LIBCAMERA_PIPELINE_RKISP1_PATH_H__
 #define __LIBCAMERA_PIPELINE_RKISP1_PATH_H__
 
+#include <memory>
 #include <vector>
 
 #include <libcamera/camera.h>
@@ -65,7 +66,7 @@ private:
 	const Size minResolution_;
 	const Size maxResolution_;
 
-	V4L2Subdevice *resizer_;
+	std::unique_ptr<V4L2Subdevice> resizer_;
 	V4L2VideoDevice *video_;
 	MediaLink *link_;
 };

src/libcamera/v4l2_subdevice.cpp

@@ -446,19 +446,17 @@ int V4L2Subdevice::setFormat(unsigned int pad, V4L2SubdeviceFormat *format,
  * \param[in] media The media device where the entity is registered
  * \param[in] entity The media entity name
  *
- * Releasing memory of the newly created instance is responsibility of the
- * caller of this function.
- *
  * \return A newly created V4L2Subdevice on success, nullptr otherwise
  */
-V4L2Subdevice *V4L2Subdevice::fromEntityName(const MediaDevice *media,
-					     const std::string &entity)
+std::unique_ptr<V4L2Subdevice>
+V4L2Subdevice::fromEntityName(const MediaDevice *media,
+			      const std::string &entity)
 {
 	MediaEntity *mediaEntity = media->getEntityByName(entity);
 	if (!mediaEntity)
 		return nullptr;
 
-	return new V4L2Subdevice(mediaEntity);
+	return std::make_unique<V4L2Subdevice>(mediaEntity);
 }
 
 std::string V4L2Subdevice::logPrefix() const