[libcamera-devel] [PATCH v5] libcamera: v4l2_device: Workaround faulty control menus
Kieran Bingham
kieran.bingham at ideasonboard.com
Thu Nov 24 15:45:53 CET 2022
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 at ovgu.de>
Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>
Signed-off-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
---
As I posted two v3 patches, I've gone straight to v5 on this.
Now there's only the common path error report, and a couple of minor
text fixes.
include/libcamera/internal/v4l2_device.h | 4 ++--
src/libcamera/v4l2_device.cpp | 28 +++++++++++++++++++-----
2 files changed, 25 insertions(+), 7 deletions(-)
diff --git a/include/libcamera/internal/v4l2_device.h b/include/libcamera/internal/v4l2_device.h
index 75304be11f77..50d4adbc5f2b 100644
--- a/include/libcamera/internal/v4l2_device.h
+++ b/include/libcamera/internal/v4l2_device.h
@@ -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,
diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
index c17b323f8af0..57a88d96b12c 100644
--- a/src/libcamera/v4l2_device.cpp
+++ b/src/libcamera/v4l2_device.cpp
@@ -529,7 +529,7 @@ std::unique_ptr<ControlId> V4L2Device::v4l2ControlId(const v4l2_query_ext_ctrl &
* \param[in] ctrl The v4l2_query_ext_ctrl that represents a V4L2 control
* \return A ControlInfo that represents \a ctrl
*/
-ControlInfo V4L2Device::v4l2ControlInfo(const v4l2_query_ext_ctrl &ctrl)
+std::optional<ControlInfo> V4L2Device::v4l2ControlInfo(const v4l2_query_ext_ctrl &ctrl)
{
switch (ctrl.type) {
case V4L2_CTRL_TYPE_U8:
@@ -566,14 +566,14 @@ ControlInfo V4L2Device::v4l2ControlInfo(const v4l2_query_ext_ctrl &ctrl)
*
* \return A ControlInfo that represents \a ctrl
*/
-ControlInfo V4L2Device::v4l2MenuControlInfo(const struct v4l2_query_ext_ctrl &ctrl)
+std::optional<ControlInfo> V4L2Device::v4l2MenuControlInfo(const struct v4l2_query_ext_ctrl &ctrl)
{
std::vector<ControlValue> indices;
struct v4l2_querymenu menu = {};
menu.id = ctrl.id;
if (ctrl.minimum < 0)
- return ControlInfo();
+ return std::nullopt;
for (int32_t index = ctrl.minimum; index <= ctrl.maximum; ++index) {
menu.index = index;
@@ -583,6 +583,14 @@ ControlInfo V4L2Device::v4l2MenuControlInfo(const struct v4l2_query_ext_ctrl &ct
indices.push_back(index);
}
+ /*
+ * Some faulty UVC devices are known to return an empty menu control.
+ * Controls without a menu option can not be set, or read, so they are
+ * not exposed.
+ */
+ if (indices.size() == 0)
+ return std::nullopt;
+
return ControlInfo(indices,
ControlValue(static_cast<int32_t>(ctrl.default_value)));
}
@@ -631,7 +639,17 @@ void V4L2Device::listControls()
controlIdMap_[ctrl.id] = controlIds_.back().get();
controlInfo_.emplace(ctrl.id, ctrl);
- ctrls.emplace(controlIds_.back().get(), v4l2ControlInfo(ctrl));
+ std::optional<ControlInfo> info = v4l2ControlInfo(ctrl);
+
+ if (!info) {
+ LOG(V4L2, Error)
+ << "Control " << ctrl.name
+ << " cannot be registered";
+
+ continue;
+ }
+
+ ctrls.emplace(controlIds_.back().get(), *info);
}
controls_ = ControlInfoMap(std::move(ctrls), controlIdMap_);
@@ -670,7 +688,7 @@ void V4L2Device::updateControlInfo()
continue;
}
- info = v4l2ControlInfo(ctrl);
+ info = *v4l2ControlInfo(ctrl);
}
}
--
2.34.1
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