[libcamera-devel] [PATCH v2] libcamera: v4l2_device: Fix variable-sized object initialization

[Laurent Pinchart]

Hi Niklas,

Thank you for the patch.

On Fri, Jun 28, 2019 at 07:00:39PM +0200, Niklas Söderlund wrote:
> Compiling with clang renders errors as a variable-sized arrays are not
> allowed to be initialized. Solve this by using memset() for v4l2Ctrls
> which is the only one of the two arrays that needs to be zeroed.
> 
>     ../../src/libcamera/v4l2_device.cpp:155:37: error: variable-sized object may not be initialized
>         const V4L2ControlInfo *controlInfo[count] = {};
>                                            ^~~~~
>     ../../src/libcamera/v4l2_device.cpp:156:36: error: variable-sized object may not be initialized
> 	    struct v4l2_ext_control v4l2Ctrls[count] = {};
> 					      ^~~~~
>     ../../src/libcamera/v4l2_device.cpp:227:37: error: variable-sized object may not be initialized
> 	    const V4L2ControlInfo *controlInfo[count] = {};
> 					       ^~~~~
>     ../../src/libcamera/v4l2_device.cpp:228:36: error: variable-sized object may not be initialized
> 	    struct v4l2_ext_control v4l2Ctrls[count] = {};
> 					      ^~~~~
> Fixes: eb068f4e67eedacd ("libcamera: v4l2_device: Implement get and set controls")
> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> ---
>  src/libcamera/v4l2_device.cpp | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> index f1821a7ba162e709..e6395341443ce70a 100644
> --- a/src/libcamera/v4l2_device.cpp
> +++ b/src/libcamera/v4l2_device.cpp
> @@ -152,8 +152,10 @@ int V4L2Device::getControls(V4L2ControlList *ctrls)
>  	if (count == 0)
>  		return 0;
>  
> -	const V4L2ControlInfo *controlInfo[count] = {};
> -	struct v4l2_ext_control v4l2Ctrls[count] = {};
> +	const V4L2ControlInfo *controlInfo[count];
> +	struct v4l2_ext_control v4l2Ctrls[count];
> +	memset(v4l2Ctrls, 0, count * sizeof(v4l2Ctrls[0]));

How about

	memset(v4l2Ctrls, 0, sizeof(v4l2Ctrls));

> +
>  	for (unsigned int i = 0; i < count; ++i) {
>  		const V4L2Control *ctrl = ctrls->getByIndex(i);
>  		const V4L2ControlInfo *info = getControlInfo(ctrl->id());
> @@ -224,8 +226,9 @@ int V4L2Device::setControls(V4L2ControlList *ctrls)
>  	if (count == 0)
>  		return 0;
>  
> -	const V4L2ControlInfo *controlInfo[count] = {};
> -	struct v4l2_ext_control v4l2Ctrls[count] = {};
> +	const V4L2ControlInfo *controlInfo[count];
> +	struct v4l2_ext_control v4l2Ctrls[count];
> +	memset(v4l2Ctrls, 0, count * sizeof(v4l2Ctrls[0]));

And here too.

If that works,

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

>  
>  	for (unsigned int i = 0; i < count; ++i) {
>  		const V4L2Control *ctrl = ctrls->getByIndex(i);

-- 
Regards,

Laurent Pinchart