chore: vendor trimmed v4l2r capture crate

libs/v4l2r/src/ioctl/dqbuf.rs

@@ -0,0 +1,66 @@
+use crate::ioctl::ioctl_and_convert;
+use crate::ioctl::IoctlConvertError;
+use crate::ioctl::IoctlConvertResult;
+use crate::ioctl::UncheckedV4l2Buffer;
+use crate::QueueType;
+
+use std::convert::TryFrom;
+use std::fmt::Debug;
+use std::os::unix::io::AsRawFd;
+
+use nix::errno::Errno;
+use thiserror::Error;
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::v4l2_buffer;
+    nix::ioctl_readwrite!(vidioc_dqbuf, b'V', 17, v4l2_buffer);
+}
+
+#[derive(Debug, Error)]
+pub enum DqBufIoctlError {
+    #[error("end-of-stream reached")]
+    Eos,
+    #[error("no buffer ready for dequeue")]
+    NotReady,
+    #[error("unexpected ioctl error: {0}")]
+    Other(Errno),
+}
+
+impl From<Errno> for DqBufIoctlError {
+    fn from(error: Errno) -> Self {
+        match error {
+            Errno::EAGAIN => Self::NotReady,
+            Errno::EPIPE => Self::Eos,
+            error => Self::Other(error),
+        }
+    }
+}
+
+impl From<DqBufIoctlError> for Errno {
+    fn from(err: DqBufIoctlError) -> Self {
+        match err {
+            DqBufIoctlError::Eos => Errno::EPIPE,
+            DqBufIoctlError::NotReady => Errno::EAGAIN,
+            DqBufIoctlError::Other(e) => e,
+        }
+    }
+}
+
+pub type DqBufError<CE> = IoctlConvertError<DqBufIoctlError, CE>;
+pub type DqBufResult<O, CE> = IoctlConvertResult<O, DqBufIoctlError, CE>;
+
+/// Safe wrapper around the `VIDIOC_DQBUF` ioctl.
+pub fn dqbuf<O>(fd: &impl AsRawFd, queue: QueueType) -> DqBufResult<O, O::Error>
+where
+    O: TryFrom<UncheckedV4l2Buffer>,
+    O::Error: std::fmt::Debug,
+{
+    let mut v4l2_buf = UncheckedV4l2Buffer::new_for_querybuf(queue, None);
+
+    ioctl_and_convert(
+        unsafe { ioctl::vidioc_dqbuf(fd.as_raw_fd(), v4l2_buf.as_mut()) }
+            .map(|_| v4l2_buf)
+            .map_err(Into::into),
+    )
+}