chore: vendor trimmed v4l2r capture crate

libs/v4l2r/src/ioctl/subscribe_event.rs

@@ -0,0 +1,210 @@
+//! Safe wrapper for the `VIDIOC_SUBSCRIBE_EVENT` and `VIDIOC_UNSUBSCRIBE_EVENT
+//! ioctls.
+
+use std::convert::TryFrom;
+use std::convert::TryInto;
+use std::os::unix::io::AsRawFd;
+
+use bitflags::bitflags;
+use nix::errno::Errno;
+use thiserror::Error;
+
+use crate::bindings;
+use crate::bindings::v4l2_event;
+use crate::bindings::v4l2_event_subscription;
+
+bitflags! {
+    #[derive(Clone, Copy, Debug)]
+    pub struct SubscribeEventFlags: u32 {
+        const SEND_INITIAL = bindings::V4L2_EVENT_SUB_FL_SEND_INITIAL;
+        const ALLOW_FEEDBACK = bindings::V4L2_EVENT_SUB_FL_ALLOW_FEEDBACK;
+    }
+
+}
+
+#[derive(Debug)]
+pub enum EventType {
+    VSync,
+    Eos,
+    Ctrl(u32),
+    FrameSync,
+    SourceChange(u32),
+    MotionDet,
+}
+
+#[derive(Debug, Error)]
+pub enum EventConversionError {
+    #[error("unrecognized event {0}")]
+    UnrecognizedEvent(u32),
+    #[error("unrecognized source change {0}")]
+    UnrecognizedSourceChange(u32),
+}
+
+impl TryFrom<&v4l2_event_subscription> for EventType {
+    type Error = EventConversionError;
+
+    fn try_from(event: &v4l2_event_subscription) -> Result<Self, Self::Error> {
+        Ok(match event.type_ {
+            bindings::V4L2_EVENT_VSYNC => EventType::VSync,
+            bindings::V4L2_EVENT_EOS => EventType::Eos,
+            bindings::V4L2_EVENT_CTRL => EventType::Ctrl(event.id),
+            bindings::V4L2_EVENT_FRAME_SYNC => EventType::FrameSync,
+            bindings::V4L2_EVENT_SOURCE_CHANGE => EventType::SourceChange(event.id),
+            bindings::V4L2_EVENT_MOTION_DET => EventType::MotionDet,
+            e => return Err(EventConversionError::UnrecognizedEvent(e)),
+        })
+    }
+}
+
+bitflags! {
+    #[derive(Clone, Copy, Debug)]
+    pub struct SrcChanges: u32 {
+        const RESOLUTION = bindings::V4L2_EVENT_SRC_CH_RESOLUTION;
+    }
+}
+
+#[derive(Debug)]
+pub enum Event {
+    SrcChangeEvent(SrcChanges),
+    Eos,
+}
+
+impl TryFrom<v4l2_event> for Event {
+    type Error = EventConversionError;
+
+    fn try_from(value: v4l2_event) -> Result<Self, Self::Error> {
+        Ok(match value.type_ {
+            bindings::V4L2_EVENT_VSYNC => todo!(),
+            bindings::V4L2_EVENT_EOS => Event::Eos,
+            bindings::V4L2_EVENT_CTRL => todo!(),
+            bindings::V4L2_EVENT_FRAME_SYNC => todo!(),
+            bindings::V4L2_EVENT_SOURCE_CHANGE => {
+                let changes = unsafe { value.u.src_change.changes };
+                Event::SrcChangeEvent(
+                    SrcChanges::from_bits(changes)
+                        .ok_or(EventConversionError::UnrecognizedSourceChange(changes))?,
+                )
+            }
+            bindings::V4L2_EVENT_MOTION_DET => todo!(),
+            t => return Err(EventConversionError::UnrecognizedEvent(t)),
+        })
+    }
+}
+
+fn build_v4l2_event_subscription(
+    event: EventType,
+    flags: SubscribeEventFlags,
+) -> v4l2_event_subscription {
+    v4l2_event_subscription {
+        type_: match event {
+            EventType::VSync => bindings::V4L2_EVENT_VSYNC,
+            EventType::Eos => bindings::V4L2_EVENT_EOS,
+            EventType::Ctrl(_) => bindings::V4L2_EVENT_CTRL,
+            EventType::FrameSync => bindings::V4L2_EVENT_FRAME_SYNC,
+            EventType::SourceChange(_) => bindings::V4L2_EVENT_SOURCE_CHANGE,
+            EventType::MotionDet => bindings::V4L2_EVENT_MOTION_DET,
+        },
+        id: match event {
+            EventType::Ctrl(id) => id,
+            EventType::SourceChange(id) => id,
+            _ => 0,
+        },
+        flags: flags.bits(),
+        ..Default::default()
+    }
+}
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::{v4l2_event, v4l2_event_subscription};
+
+    nix::ioctl_read!(vidioc_dqevent, b'V', 89, v4l2_event);
+    nix::ioctl_write_ptr!(vidioc_subscribe_event, b'V', 90, v4l2_event_subscription);
+    nix::ioctl_write_ptr!(vidioc_unsubscribe_event, b'V', 91, v4l2_event_subscription);
+}
+
+#[derive(Debug, Error)]
+pub enum SubscribeEventError {
+    #[error("ioctl error: {0}")]
+    IoctlError(#[from] Errno),
+}
+
+impl From<SubscribeEventError> for Errno {
+    fn from(err: SubscribeEventError) -> Self {
+        match err {
+            SubscribeEventError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_SUBSCRIBE_EVENT` ioctl.
+pub fn subscribe_event(
+    fd: &impl AsRawFd,
+    event: EventType,
+    flags: SubscribeEventFlags,
+) -> Result<(), SubscribeEventError> {
+    let subscription = build_v4l2_event_subscription(event, flags);
+
+    unsafe { ioctl::vidioc_subscribe_event(fd.as_raw_fd(), &subscription) }?;
+    Ok(())
+}
+
+/// Safe wrapper around the `VIDIOC_UNSUBSCRIBE_EVENT` ioctl.
+pub fn unsubscribe_event(fd: &impl AsRawFd, event: EventType) -> Result<(), SubscribeEventError> {
+    let subscription = build_v4l2_event_subscription(event, SubscribeEventFlags::empty());
+
+    unsafe { ioctl::vidioc_unsubscribe_event(fd.as_raw_fd(), &subscription) }?;
+    Ok(())
+}
+
+/// Safe wrapper around the `VIDIOC_UNSUBSCRIBE_EVENT` ioctl to unsubscribe from all events.
+pub fn unsubscribe_all_events(fd: &impl AsRawFd) -> Result<(), SubscribeEventError> {
+    let subscription = v4l2_event_subscription {
+        type_: bindings::V4L2_EVENT_ALL,
+        ..Default::default()
+    };
+
+    unsafe { ioctl::vidioc_unsubscribe_event(fd.as_raw_fd(), &subscription) }?;
+    Ok(())
+}
+
+#[derive(Debug, Error)]
+pub enum DqEventError {
+    #[error("no event ready for dequeue")]
+    NotReady,
+    #[error("error while converting event")]
+    EventConversionError,
+    #[error("unexpected ioctl error: {0}")]
+    IoctlError(Errno),
+}
+
+impl From<Errno> for DqEventError {
+    fn from(error: Errno) -> Self {
+        match error {
+            Errno::ENOENT => Self::NotReady,
+            error => Self::IoctlError(error),
+        }
+    }
+}
+
+impl From<DqEventError> for Errno {
+    fn from(err: DqEventError) -> Self {
+        match err {
+            DqEventError::NotReady => Errno::ENOENT,
+            DqEventError::EventConversionError => Errno::EINVAL,
+            DqEventError::IoctlError(e) => e,
+        }
+    }
+}
+
+pub fn dqevent<O: TryFrom<v4l2_event>>(fd: &impl AsRawFd) -> Result<O, DqEventError> {
+    let mut event: v4l2_event = Default::default();
+
+    match unsafe { ioctl::vidioc_dqevent(fd.as_raw_fd(), &mut event) } {
+        Ok(_) => Ok(event
+            .try_into()
+            .map_err(|_| DqEventError::EventConversionError)?),
+        Err(Errno::ENOENT) => Err(DqEventError::NotReady),
+        Err(e) => Err(DqEventError::IoctlError(e)),
+    }
+}