chore: vendor trimmed v4l2r capture crate

libs/v4l2r/src/ioctl/frameintervals.rs

@@ -0,0 +1,82 @@
+use nix::errno::Errno;
+use std::os::unix::io::AsRawFd;
+use thiserror::Error;
+
+use crate::bindings;
+use crate::bindings::v4l2_frmivalenum;
+use crate::PixelFormat;
+
+/// A wrapper for the 'v4l2_frmivalenum' union member types
+#[derive(Debug)]
+pub enum FrmIvalTypes<'a> {
+    Discrete(&'a bindings::v4l2_fract),
+    StepWise(&'a bindings::v4l2_frmival_stepwise),
+}
+
+impl v4l2_frmivalenum {
+    /// Safely access the intervals member of the struct based on the
+    /// returned type.
+    pub fn intervals(&self) -> Option<FrmIvalTypes<'_>> {
+        match self.type_ {
+            // SAFETY: the member of the union that gets used by the driver
+            // is determined by the type
+            bindings::v4l2_frmivaltypes_V4L2_FRMIVAL_TYPE_DISCRETE => {
+                Some(FrmIvalTypes::Discrete(unsafe {
+                    &self.__bindgen_anon_1.discrete
+                }))
+            }
+
+            // SAFETY: the member of the union that gets used by the driver
+            // is determined by the type
+            bindings::v4l2_frmivaltypes_V4L2_FRMIVAL_TYPE_CONTINUOUS
+            | bindings::v4l2_frmivaltypes_V4L2_FRMIVAL_TYPE_STEPWISE => {
+                Some(FrmIvalTypes::StepWise(unsafe {
+                    &self.__bindgen_anon_1.stepwise
+                }))
+            }
+
+            _ => None,
+        }
+    }
+}
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::v4l2_frmivalenum;
+    nix::ioctl_readwrite!(vidioc_enum_frameintervals, b'V', 75, v4l2_frmivalenum);
+}
+
+#[derive(Debug, Error)]
+pub enum FrameIntervalsError {
+    #[error("Unexpected ioctl error: {0}")]
+    IoctlError(nix::Error),
+}
+
+impl From<FrameIntervalsError> for Errno {
+    fn from(err: FrameIntervalsError) -> Self {
+        match err {
+            FrameIntervalsError::IoctlError(e) => e,
+        }
+    }
+}
+/// Safe wrapper around the `VIDIOC_ENUM_FRAMEINTERVALS` ioctl.
+pub fn enum_frame_intervals<O: From<v4l2_frmivalenum>>(
+    fd: &impl AsRawFd,
+    index: u32,
+    pixel_format: PixelFormat,
+    width: u32,
+    height: u32,
+) -> Result<O, FrameIntervalsError> {
+    let mut frame_interval = v4l2_frmivalenum {
+        index,
+        pixel_format: pixel_format.into(),
+        width,
+        height,
+        ..Default::default()
+    };
+
+    match unsafe { ioctl::vidioc_enum_frameintervals(fd.as_raw_fd(), &mut frame_interval) } {
+        Ok(_) => Ok(O::from(frame_interval)),
+        Err(e) => Err(FrameIntervalsError::IoctlError(e)),
+    }
+}