[libcamera-devel] [PATCH] file_sink.cpp: Avoid dangling-reference

[Barnabás Pőcze]

Hi


On 2023. január 24., kedd 10:22, Khem Raj via libcamera-devel <libcamera-devel at lists.libcamera.org> wrote:

> Fixes following errors with gcc-13
> 
> ../git/src/cam/file_sink.cpp:92:45: error: possibly dangling reference to a temporary [-Werror=dangling-reference]
>    92 |                 const FrameMetadata::Plane &meta = buffer->metadata().planes()[i];
>       |                                             ^~~~
> ../git/src/cam/file_sink.cpp:92:81: note: the temporary was destroyed at the end of the full expression '(& buffer->libcamera::FrameBuffer::metadata())->libcamera::FrameMetadata::planes().libcamera::Span<const libcamera::FrameMetadata::Plane>::operator[](i)'
>    92 |                 const FrameMetadata::Plane &meta = buffer->metadata().planes()[i];
>       |                                                                                 ^
> cc1plus: all warnings being treated as errors

I think this warning is a false-positive. See a similar example here: https://gcc.godbolt.org/z/rf8v4j6YG
This should probably be reported to the GCC bug tracker if that has not already been done.


> 
> Signed-off-by: Khem Raj <raj.khem at gmail.com>
> ---
>  src/cam/file_sink.cpp | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/src/cam/file_sink.cpp b/src/cam/file_sink.cpp
> index 45213d4a..897c4b37 100644
> --- a/src/cam/file_sink.cpp
> +++ b/src/cam/file_sink.cpp
> @@ -89,13 +89,13 @@ void FileSink::writeBuffer(const Stream *stream, FrameBuffer *buffer)
>  	Image *image = mappedBuffers_[buffer].get();
> 
>  	for (unsigned int i = 0; i < buffer->planes().size(); ++i) {
> -		const FrameMetadata::Plane &meta = buffer->metadata().planes()[i];
> +		unsigned int bytesused = buffer->metadata().planes()[i].bytesused;
> 
>  		Span<uint8_t> data = image->data(i);
> -		unsigned int length = std::min<unsigned int>(meta.bytesused, data.size());
> +		unsigned int length = std::min<unsigned int>(bytesused, data.size());
> 
> -		if (meta.bytesused > data.size())
> -			std::cerr << "payload size " << meta.bytesused
> +		if (bytesused > data.size())
> +			std::cerr << "payload size " << bytesused
>  				  << " larger than plane size " << data.size()
>  				  << std::endl;
> 
> --
> 2.39.1
> 
> 


Regards,
Barnabás Pőcze