[libcamera-devel] [PATCH] v4l2: v4l2_camera_proxy, v4l2_camera: Check return values of read/write

[Umang Jain]

Hi Paul,

Thank you for the patch.

On 6/16/20 4:24 PM, Paul Elder wrote:
> The return value of the write to the eventfd (to signal POLLIN) from
> V4L2Camera and the read from the eventfd (to clear POLLIN) from
> V4L2CameraProxy was not ignored. Check the return value, and print an
Maybe you mean s/was not ignored/should not be ignored ?
> error message.
>
> Reported-by: Coverity CID=290743
> Reported-by: Coverity CID=290744
> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> ---
>   src/v4l2/v4l2_camera.cpp       | 4 +++-
>   src/v4l2/v4l2_camera_proxy.cpp | 4 +++-
>   2 files changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/src/v4l2/v4l2_camera.cpp b/src/v4l2/v4l2_camera.cpp
> index 3c36932..9a1ebc8 100644
> --- a/src/v4l2/v4l2_camera.cpp
> +++ b/src/v4l2/v4l2_camera.cpp
> @@ -91,7 +91,9 @@ void V4L2Camera::requestComplete(Request *request)
>   	bufferLock_.unlock();
>   
>   	uint64_t data = 1;
> -	::write(efd_, &data, sizeof(data));
> +	int ret = ::write(efd_, &data, sizeof(data));
> +	if (ret != sizeof(data))
> +		LOG(V4L2Compat, Error) << "Failed to signal eventfd POLLIN";
>   
>   	bufferSema_.release();
>   }
> diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
> index 308a8ab..17477ab 100644
> --- a/src/v4l2/v4l2_camera_proxy.cpp
> +++ b/src/v4l2/v4l2_camera_proxy.cpp
> @@ -454,7 +454,9 @@ int V4L2CameraProxy::vidioc_dqbuf(struct v4l2_buffer *arg)
>   	currentBuf_ = (currentBuf_ + 1) % bufferCount_;
>   
>   	uint64_t data;
> -	::read(efd_, &data, sizeof(data));
> +	ret = ::read(efd_, &data, sizeof(data));
> +	if (ret != sizeof(data))
> +		LOG(V4L2Compat, Error) << "Failed to clear eventfd POLLIN";
>   
>   	return 0;
>   }