[libcamera-devel] [PATCH] libcamera: v4l2_device: openat(2) with O_CLOEXEC to cleanup after exec(3)

[Laurent Pinchart]

Hi Elias,

Thank you for the patch.

On Sat, Mar 11, 2023 at 01:05:25PM -0600, Elias Naur via libcamera-devel wrote:
> It's generally a good idea to openat(2) with O_CLOEXEC, but this patch
> also fixes a problem where the v4l2 devices would report -EBUSY after
> an exec(3).

Could you elaborate a bit on this -EBUSY problem ?

> Signed-off-by: Elias Naur <mail at eliasnaur.com>
> ---
>  src/libcamera/v4l2_device.cpp | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git src/libcamera/v4l2_device.cpp src/libcamera/v4l2_device.cpp
> index 57a88d96..ad9d1e37 100644
> --- src/libcamera/v4l2_device.cpp
> +++ src/libcamera/v4l2_device.cpp
> @@ -86,7 +86,7 @@ int V4L2Device::open(unsigned int flags)
>  		return -EBUSY;
>  	}
>  
> -	UniqueFD fd(syscall(SYS_openat, AT_FDCWD, deviceNode_.c_str(), flags));
> +	UniqueFD fd(syscall(SYS_openat, AT_FDCWD, deviceNode_.c_str(), flags|O_CLOEXEC));

There should be spaces around the '|'. The utils/checkstyle.py script
should have reported that. You can automate running checkstyle.py as a
git post-commit (or pre-commit, if desired) hook by copying
utils/hooks/post-commit to .git/hooks/.

There's no need to submit a v2 of this patch just for this, I can fix it
locally.

>  	if (!fd.isValid()) {
>  		int ret = -errno;
>  		LOG(V4L2, Error) << "Failed to open V4L2 device '"

-- 
Regards,

Laurent Pinchart