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libcamera: v4l2_device: Workaround faulty control menus

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Some UVC cameras have been identified that can provide V4L2 menu
controls without any menu items.

This leads to a segfault where we try to construct a
ControlInfo(Span<>,default) with an empty span.

Convert the v4l2ControlInfo and v4l2MenuControlInfo helper functions to
return std::optional<ControlInfo> to be able to account in the caller if
the control is valid, and only add acceptable controls to the supported
control list.

Menu controls without a list of menu items are no longer added as a
valid control and a warning is logged.

This also fixes a potential crash that would have occured in the
unlikely event that a ctrl.minimum was set to less than 0.

Bug: https://bugs.libcamera.org/show_bug.cgi?id=167
Reported-by: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
This commit is contained in:
Kieran Bingham 2022-11-01 18:00:51 +00:00
parent 1cd7646f97
commit 96ed45b971
2 changed files with 25 additions and 7 deletions
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4
include/libcamera/internal/v4l2_device.h
View file

@ -70,8 +70,8 @@ protected:
private:
static ControlType v4l2CtrlType(uint32_t ctrlType);
static std::unique_ptr<ControlId> v4l2ControlId(const v4l2_query_ext_ctrl &ctrl);
ControlInfo v4l2ControlInfo(const v4l2_query_ext_ctrl &ctrl);
ControlInfo v4l2MenuControlInfo(const v4l2_query_ext_ctrl &ctrl);
std::optional<ControlInfo> v4l2ControlInfo(const v4l2_query_ext_ctrl &ctrl);
std::optional<ControlInfo> v4l2MenuControlInfo(const v4l2_query_ext_ctrl &ctrl);
void listControls();
void updateControls(ControlList *ctrls,