[libcamera-devel] [PATCH] qcam: Fix ViewFinder memory leak

[Kieran Bingham]

Hi Laurent,

On 24/09/2019 12:54, Laurent Pinchart wrote:
> Hello,
> 
> On Tue, Sep 24, 2019 at 12:51:32PM +0100, Kieran Bingham wrote:
>> On 24/09/2019 09:16, Jacopo Mondi wrote:
>>> On Mon, Sep 23, 2019 at 02:22:29PM +0100, Kieran Bingham wrote:
>>>> When setting the format on the ViewFinder, a new image_ is allocated.
>>>> Any change in format deletes the existing allocation, but it is not
>>>> cleaned up on shutdown:
>>>>
>>>> Direct leak of 32 byte(s) in 1 object(s) allocated from:
>>>>     #0 0x7f0bf8a7e17f in operator new(unsigned long) (/usr/lib/x86_64-linux-gnu/libasan.so.5+0x10e17f)
>>>>     #1 0x564c7205f7b0 in ViewFinder::setFormat(unsigned int, unsigned int, unsigned int) ../src/qcam/viewfinder.cpp:43
>>>>     #2 0x564c71fec467 in MainWindow::startCapture() ../src/qcam/main_window.cpp:152
>>>>     #3 0x564c71fe6c1a in MainWindow::MainWindow(libcamera::CameraManager*, OptionsParser::Options const&) ../src/qcam/main_window.cpp:40
>>>>     #4 0x564c71fdf133 in main ../src/qcam/main.cpp:76
>>>>     #5 0x7f0bf5944b6a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x26b6a)
>>>>
>>>> Provide a ViewFinder destructor, and delete the allocation as
>>>> appropriate.
>>>
>>> Good catch, but I don't see where the viewfinder gets destroyed in
>>> main_window.cpp. How does the newly added destructor gets called?
>>
>> Intriguing, the addition of the destructor made the LeakSanitizer
>> warning go away, however I believe you are right. There is no explicit
>> call to delete the ViewFinder which is created as part of the MainWindow.
>>
>> I'll add this, and respin a v2.
> 
> No need to, https://doc.qt.io/qt-5/qobject.html#dtor.QObject


Aha - ok so because it's constructed with 'this' passed in the
destruction is linked:
        viewfinder_ = new ViewFinder(this);

That explains why just cleaning up the QImage leak was enough.

I'll stick with V1 then.

Regards

Kieran


> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> 
>>>> Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
>>>> ---
>>>>  src/qcam/viewfinder.cpp | 5 +++++
>>>>  src/qcam/viewfinder.h   | 1 +
>>>>  2 files changed, 6 insertions(+)
>>>>
>>>> diff --git a/src/qcam/viewfinder.cpp b/src/qcam/viewfinder.cpp
>>>> index 224a227ddd5b..98a8ab68e5f6 100644
>>>> --- a/src/qcam/viewfinder.cpp
>>>> +++ b/src/qcam/viewfinder.cpp
>>>> @@ -16,6 +16,11 @@ ViewFinder::ViewFinder(QWidget *parent)
>>>>  {
>>>>  }
>>>>
>>>> +ViewFinder::~ViewFinder()
>>>> +{
>>>> +	delete image_;
>>>> +}
>>>> +
>>>>  void ViewFinder::display(const unsigned char *raw, size_t size)
>>>>  {
>>>>  	converter_.convert(raw, size, image_);
>>>> diff --git a/src/qcam/viewfinder.h b/src/qcam/viewfinder.h
>>>> index c9ca98913e05..33bdb1460f84 100644
>>>> --- a/src/qcam/viewfinder.h
>>>> +++ b/src/qcam/viewfinder.h
>>>> @@ -17,6 +17,7 @@ class ViewFinder : public QLabel
>>>>  {
>>>>  public:
>>>>  	ViewFinder(QWidget *parent);
>>>> +	~ViewFinder();
>>>>
>>>>  	int setFormat(unsigned int format, unsigned int width,
>>>>  		      unsigned int height);
> 

-- 
Regards
--
Kieran