chore: vendor trimmed v4l2r capture crate

libs/v4l2r/src/ioctl/expbuf.rs

@@ -0,0 +1,61 @@
+//! Safe wrapper for the `VIDIOC_EXPBUF` ioctl.
+use bitflags::bitflags;
+use nix::errno::Errno;
+use nix::fcntl::OFlag;
+use std::os::unix::io::{AsRawFd, FromRawFd};
+use thiserror::Error;
+
+use crate::bindings::v4l2_exportbuffer;
+use crate::QueueType;
+
+bitflags! {
+    /// Flags that can be passed when exporting the buffer.
+    #[derive(Clone, Copy, Debug)]
+    pub struct ExpbufFlags: u32 {
+        const CLOEXEC = OFlag::O_CLOEXEC.bits() as u32;
+        const RDONLY = OFlag::O_RDONLY.bits() as u32;
+        const WRONLY = OFlag::O_WRONLY.bits() as u32;
+        const RDWR = OFlag::O_RDWR.bits() as u32;
+    }
+}
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::v4l2_exportbuffer;
+    nix::ioctl_readwrite!(vidioc_expbuf, b'V', 16, v4l2_exportbuffer);
+}
+
+#[derive(Debug, Error)]
+pub enum ExpbufError {
+    #[error("ioctl error: {0}")]
+    IoctlError(#[from] Errno),
+}
+
+impl From<ExpbufError> for Errno {
+    fn from(err: ExpbufError) -> Self {
+        match err {
+            ExpbufError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_EXPBUF` ioctl.
+pub fn expbuf<R: FromRawFd>(
+    fd: &impl AsRawFd,
+    queue: QueueType,
+    index: usize,
+    plane: usize,
+    flags: ExpbufFlags,
+) -> Result<R, ExpbufError> {
+    let mut v4l2_expbuf = v4l2_exportbuffer {
+        type_: queue as u32,
+        index: index as u32,
+        plane: plane as u32,
+        flags: flags.bits(),
+        ..Default::default()
+    };
+
+    unsafe { ioctl::vidioc_expbuf(fd.as_raw_fd(), &mut v4l2_expbuf) }?;
+
+    Ok(unsafe { R::from_raw_fd(v4l2_expbuf.fd) })
+}