chore: vendor trimmed v4l2r capture crate

libs/v4l2r/src/bindings.rs

@@ -0,0 +1,8 @@
+#![allow(dead_code)]
+#![allow(non_upper_case_globals)]
+#![allow(non_camel_case_types)]
+#![allow(non_snake_case)]
+#![allow(deref_nullptr)]
+#![allow(clippy::all)]
+
+include!(concat!(env!("OUT_DIR"), "/bindings.rs"));

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),
+    )
+}

libs/v4l2r/src/ioctl/enum_fmt.rs

@@ -0,0 +1,137 @@
+//! Safe wrapper for the `VIDIOC_ENUM_FMT` ioctl.
+use super::string_from_cstr;
+use crate::bindings;
+use crate::bindings::v4l2_fmtdesc;
+use crate::{PixelFormat, QueueType};
+use bitflags::bitflags;
+use log::error;
+use nix::errno::Errno;
+use std::fmt;
+use std::os::unix::io::AsRawFd;
+use thiserror::Error;
+
+bitflags! {
+    /// Flags returned by the `VIDIOC_ENUM_FMT` ioctl into the `flags` field of
+    /// `struct v4l2_fmtdesc`.
+    #[derive(Clone, Copy, Debug)]
+    pub struct FormatFlags: u32 {
+        const COMPRESSED = bindings::V4L2_FMT_FLAG_COMPRESSED;
+        const EMULATED = bindings::V4L2_FMT_FLAG_EMULATED;
+    }
+}
+/// Quickly get the Fourcc code of a format.
+impl From<v4l2_fmtdesc> for PixelFormat {
+    fn from(fmtdesc: v4l2_fmtdesc) -> Self {
+        fmtdesc.pixelformat.into()
+    }
+}
+
+/// Safe variant of the `v4l2_fmtdesc` struct, to be used with `enum_fmt`.
+#[derive(Debug)]
+pub struct FmtDesc {
+    pub flags: FormatFlags,
+    pub description: String,
+    pub pixelformat: PixelFormat,
+}
+
+impl fmt::Display for FmtDesc {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(
+            f,
+            "{}: {} {}",
+            self.pixelformat,
+            self.description,
+            if self.flags.is_empty() {
+                "".into()
+            } else {
+                format!("({:?})", self.flags)
+            }
+        )
+    }
+}
+
+impl From<v4l2_fmtdesc> for FmtDesc {
+    fn from(fmtdesc: v4l2_fmtdesc) -> Self {
+        FmtDesc {
+            flags: FormatFlags::from_bits_truncate(fmtdesc.flags),
+            description: string_from_cstr(&fmtdesc.description).unwrap_or_else(|_| "".into()),
+            pixelformat: fmtdesc.pixelformat.into(),
+        }
+    }
+}
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::v4l2_fmtdesc;
+    nix::ioctl_readwrite!(vidioc_enum_fmt, b'V', 2, v4l2_fmtdesc);
+}
+
+#[derive(Debug, Error)]
+pub enum EnumFmtError {
+    #[error("ioctl error: {0}")]
+    IoctlError(#[from] nix::Error),
+}
+
+impl From<EnumFmtError> for Errno {
+    fn from(err: EnumFmtError) -> Self {
+        match err {
+            EnumFmtError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_ENUM_FMT` ioctl.
+pub fn enum_fmt<T: From<v4l2_fmtdesc>>(
+    fd: &impl AsRawFd,
+    queue: QueueType,
+    index: u32,
+) -> Result<T, EnumFmtError> {
+    let mut fmtdesc = v4l2_fmtdesc {
+        type_: queue as u32,
+        index,
+        ..Default::default()
+    };
+    unsafe { ioctl::vidioc_enum_fmt(fd.as_raw_fd(), &mut fmtdesc) }?;
+
+    Ok(T::from(fmtdesc))
+}
+
+/// Iterator over the formats of the given queue. This takes a reference to the
+/// device's file descriptor so no operation that could affect the format
+/// enumeration can take place while the iterator exists.
+pub struct FormatIterator<'a, F: AsRawFd> {
+    fd: &'a F,
+    queue: QueueType,
+    index: u32,
+}
+
+impl<'a, F: AsRawFd> FormatIterator<'a, F> {
+    /// Create a new iterator listing all the currently valid formats on
+    /// `queue`.
+    pub fn new(fd: &'a F, queue: QueueType) -> Self {
+        FormatIterator {
+            fd,
+            queue,
+            index: 0,
+        }
+    }
+}
+
+impl<'a, F: AsRawFd> Iterator for FormatIterator<'a, F> {
+    type Item = FmtDesc;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match enum_fmt(self.fd, self.queue, self.index) {
+            Ok(fmtdesc) => {
+                self.index += 1;
+                Some(fmtdesc)
+            }
+            // EINVAL means we have reached the last format.
+            Err(EnumFmtError::IoctlError(Errno::EINVAL)) => None,
+            _ => {
+                error!("Unexpected return value for VIDIOC_ENUM_FMT!");
+                None
+            }
+        }
+    }
+}

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) })
+}

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)),
+    }
+}

libs/v4l2r/src/ioctl/framesizes.rs

@@ -0,0 +1,79 @@
+use nix::errno::Errno;
+use std::os::unix::io::AsRawFd;
+use thiserror::Error;
+
+use crate::bindings;
+use crate::bindings::v4l2_frmsizeenum;
+use crate::PixelFormat;
+
+/// A wrapper for the 'v4l2_frmsizeenum' union member types
+#[derive(Debug)]
+pub enum FrmSizeTypes<'a> {
+    Discrete(&'a bindings::v4l2_frmsize_discrete),
+    StepWise(&'a bindings::v4l2_frmsize_stepwise),
+}
+
+impl v4l2_frmsizeenum {
+    /// Safely access the size member of the struct based on the
+    /// returned type.
+    pub fn size(&self) -> Option<FrmSizeTypes<'_>> {
+        match self.type_ {
+            // SAFETY: the member of the union that gets used by the driver
+            // is determined by the type
+            bindings::v4l2_frmsizetypes_V4L2_FRMSIZE_TYPE_DISCRETE => {
+                Some(FrmSizeTypes::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_frmsizetypes_V4L2_FRMSIZE_TYPE_CONTINUOUS
+            | bindings::v4l2_frmsizetypes_V4L2_FRMSIZE_TYPE_STEPWISE => {
+                Some(FrmSizeTypes::StepWise(unsafe {
+                    &self.__bindgen_anon_1.stepwise
+                }))
+            }
+
+            _ => None,
+        }
+    }
+}
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::v4l2_frmsizeenum;
+    nix::ioctl_readwrite!(vidioc_enum_framesizes, b'V', 74, v4l2_frmsizeenum);
+}
+
+#[derive(Debug, Error)]
+pub enum FrameSizeError {
+    #[error("Unexpected ioctl error: {0}")]
+    IoctlError(nix::Error),
+}
+
+impl From<FrameSizeError> for Errno {
+    fn from(err: FrameSizeError) -> Self {
+        match err {
+            FrameSizeError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_ENUM_FRAMESIZES` ioctl.
+pub fn enum_frame_sizes<O: From<v4l2_frmsizeenum>>(
+    fd: &impl AsRawFd,
+    index: u32,
+    pixel_format: PixelFormat,
+) -> Result<O, FrameSizeError> {
+    let mut frame_size = v4l2_frmsizeenum {
+        index,
+        pixel_format: pixel_format.into(),
+        ..Default::default()
+    };
+
+    match unsafe { ioctl::vidioc_enum_framesizes(fd.as_raw_fd(), &mut frame_size) } {
+        Ok(_) => Ok(O::from(frame_size)),
+        Err(e) => Err(FrameSizeError::IoctlError(e)),
+    }
+}

libs/v4l2r/src/ioctl/g_dv_timings.rs

@@ -0,0 +1,189 @@
+use std::os::unix::io::AsRawFd;
+
+use enumn::N;
+use nix::errno::Errno;
+use thiserror::Error;
+
+use crate::bindings;
+use crate::bindings::v4l2_dv_timings;
+use crate::bindings::v4l2_dv_timings_cap;
+use crate::bindings::v4l2_enum_dv_timings;
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::v4l2_dv_timings;
+    use crate::bindings::v4l2_dv_timings_cap;
+    use crate::bindings::v4l2_enum_dv_timings;
+
+    nix::ioctl_readwrite!(vidioc_s_dv_timings, b'V', 87, v4l2_dv_timings);
+    nix::ioctl_readwrite!(vidioc_g_dv_timings, b'V', 88, v4l2_dv_timings);
+    nix::ioctl_readwrite!(vidioc_enum_dv_timings, b'V', 98, v4l2_enum_dv_timings);
+    nix::ioctl_read!(vidioc_query_dv_timings, b'V', 99, v4l2_dv_timings);
+    nix::ioctl_readwrite!(vidioc_dv_timings_cap, b'V', 100, v4l2_dv_timings_cap);
+}
+
+#[derive(Debug, N)]
+#[repr(u32)]
+pub enum DvTimingsType {
+    Bt6561120 = bindings::V4L2_DV_BT_656_1120,
+}
+
+#[derive(Debug, Error)]
+pub enum GDvTimingsError {
+    #[error("ioctl not supported or invalid parameters")]
+    Invalid,
+    #[error("Digital video timings are not supported on this input or output")]
+    Unsupported,
+    #[error("Device is busy and cannot change timings")]
+    Busy,
+    #[error("ioctl error: {0}")]
+    IoctlError(Errno),
+}
+
+impl From<GDvTimingsError> for Errno {
+    fn from(err: GDvTimingsError) -> Self {
+        match err {
+            GDvTimingsError::Invalid => Errno::EINVAL,
+            GDvTimingsError::Unsupported => Errno::ENODATA,
+            GDvTimingsError::Busy => Errno::EBUSY,
+            GDvTimingsError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_S_DV_TIMINGS` ioctl.
+pub fn s_dv_timings<I: Into<v4l2_dv_timings>, O: From<v4l2_dv_timings>>(
+    fd: &impl AsRawFd,
+    timings: I,
+) -> Result<O, GDvTimingsError> {
+    let mut timings: v4l2_dv_timings = timings.into();
+
+    match unsafe { ioctl::vidioc_s_dv_timings(fd.as_raw_fd(), &mut timings) } {
+        Ok(_) => Ok(O::from(timings)),
+        Err(Errno::EINVAL) => Err(GDvTimingsError::Invalid),
+        Err(Errno::ENODATA) => Err(GDvTimingsError::Unsupported),
+        Err(Errno::EBUSY) => Err(GDvTimingsError::Busy),
+        Err(e) => Err(GDvTimingsError::IoctlError(e)),
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_G_DV_TIMINGS` ioctl.
+pub fn g_dv_timings<O: From<v4l2_dv_timings>>(fd: &impl AsRawFd) -> Result<O, GDvTimingsError> {
+    let mut timings = v4l2_dv_timings {
+        ..Default::default()
+    };
+
+    match unsafe { ioctl::vidioc_g_dv_timings(fd.as_raw_fd(), &mut timings) } {
+        Ok(_) => Ok(O::from(timings)),
+        Err(Errno::EINVAL) => Err(GDvTimingsError::Invalid),
+        Err(Errno::ENODATA) => Err(GDvTimingsError::Unsupported),
+        Err(Errno::EBUSY) => Err(GDvTimingsError::Busy),
+        Err(e) => Err(GDvTimingsError::IoctlError(e)),
+    }
+}
+
+#[derive(Debug, Error)]
+pub enum EnumDvTimingsError {
+    #[error("timing index is out of bounds")]
+    Invalid,
+    #[error("Digital video timings are not supported on this input or output")]
+    Unsupported,
+    #[error("ioctl error: {0}")]
+    IoctlError(Errno),
+}
+
+impl From<EnumDvTimingsError> for Errno {
+    fn from(err: EnumDvTimingsError) -> Self {
+        match err {
+            EnumDvTimingsError::Invalid => Errno::EINVAL,
+            EnumDvTimingsError::Unsupported => Errno::ENODATA,
+            EnumDvTimingsError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_ENUM_DV_TIMINGS` ioctl.
+pub fn enum_dv_timings<O: From<v4l2_dv_timings>>(
+    fd: &impl AsRawFd,
+    index: u32,
+) -> Result<O, EnumDvTimingsError> {
+    let mut timings = v4l2_enum_dv_timings {
+        index,
+        ..Default::default()
+    };
+
+    match unsafe { ioctl::vidioc_enum_dv_timings(fd.as_raw_fd(), &mut timings) } {
+        Ok(_) => Ok(O::from(timings.timings)),
+        Err(Errno::EINVAL) => Err(EnumDvTimingsError::Invalid),
+        Err(Errno::ENODATA) => Err(EnumDvTimingsError::Unsupported),
+        Err(e) => Err(EnumDvTimingsError::IoctlError(e)),
+    }
+}
+
+#[derive(Debug, Error)]
+pub enum QueryDvTimingsError {
+    #[error("Digital video timings are not supported on this input or output")]
+    Unsupported,
+    #[error("No timings could be detected because no signal was found")]
+    NoLink,
+    #[error("Unstable signal")]
+    UnstableSignal,
+    #[error("ioctl error: {0}")]
+    IoctlError(Errno),
+}
+
+impl From<QueryDvTimingsError> for Errno {
+    fn from(err: QueryDvTimingsError) -> Self {
+        match err {
+            QueryDvTimingsError::Unsupported => Errno::ENODATA,
+            QueryDvTimingsError::NoLink => Errno::ENOLINK,
+            QueryDvTimingsError::UnstableSignal => Errno::ENOLCK,
+            QueryDvTimingsError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_QUERY_DV_TIMINGS` ioctl.
+pub fn query_dv_timings<O: From<v4l2_dv_timings>>(
+    fd: &impl AsRawFd,
+) -> Result<O, QueryDvTimingsError> {
+    let mut timings = v4l2_dv_timings {
+        ..Default::default()
+    };
+
+    match unsafe { ioctl::vidioc_query_dv_timings(fd.as_raw_fd(), &mut timings) } {
+        Ok(_) => Ok(O::from(timings)),
+        Err(Errno::ENODATA) => Err(QueryDvTimingsError::Unsupported),
+        Err(Errno::ENOLINK) => Err(QueryDvTimingsError::NoLink),
+        Err(Errno::ENOLCK) => Err(QueryDvTimingsError::UnstableSignal),
+        Err(e) => Err(QueryDvTimingsError::IoctlError(e)),
+    }
+}
+
+#[derive(Debug, Error)]
+pub enum DvTimingsCapError {
+    #[error("ioctl error: {0}")]
+    IoctlError(Errno),
+}
+
+impl From<DvTimingsCapError> for Errno {
+    fn from(err: DvTimingsCapError) -> Self {
+        match err {
+            DvTimingsCapError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_DV_TIMINGS_CAP` ioctl.
+pub fn dv_timings_cap<O: From<v4l2_dv_timings_cap>>(
+    fd: &impl AsRawFd,
+) -> Result<O, DvTimingsCapError> {
+    let mut caps = v4l2_dv_timings_cap {
+        ..Default::default()
+    };
+
+    match unsafe { ioctl::vidioc_dv_timings_cap(fd.as_raw_fd(), &mut caps) } {
+        Ok(_) => Ok(O::from(caps)),
+        Err(e) => Err(DvTimingsCapError::IoctlError(e)),
+    }
+}

libs/v4l2r/src/ioctl/g_fmt.rs

@@ -0,0 +1,300 @@
+//! Safe wrapper for the `VIDIOC_(G|S|TRY)_FMT` ioctls.
+use nix::errno::Errno;
+use std::convert::{From, Into, TryFrom, TryInto};
+use std::default::Default;
+use std::os::unix::io::AsRawFd;
+use thiserror::Error;
+
+use crate::bindings;
+use crate::bindings::v4l2_format;
+use crate::Format;
+use crate::FormatConversionError;
+use crate::PlaneLayout;
+use crate::QueueType;
+
+impl TryFrom<(QueueType, &Format)> for v4l2_format {
+    type Error = FormatConversionError;
+
+    fn try_from((queue, format): (QueueType, &Format)) -> Result<Self, Self::Error> {
+        Ok(v4l2_format {
+            type_: queue as u32,
+            fmt: match queue {
+                QueueType::VideoCaptureMplane | QueueType::VideoOutputMplane => {
+                    bindings::v4l2_format__bindgen_ty_1 {
+                        pix_mp: {
+                            if format.plane_fmt.len() > bindings::VIDEO_MAX_PLANES as usize {
+                                return Err(Self::Error::TooManyPlanes(format.plane_fmt.len()));
+                            }
+
+                            let mut pix_mp = bindings::v4l2_pix_format_mplane {
+                                width: format.width,
+                                height: format.height,
+                                pixelformat: format.pixelformat.into(),
+                                num_planes: format.plane_fmt.len() as u8,
+                                plane_fmt: Default::default(),
+                                ..Default::default()
+                            };
+
+                            for (plane, v4l2_plane) in
+                                format.plane_fmt.iter().zip(pix_mp.plane_fmt.iter_mut())
+                            {
+                                *v4l2_plane = plane.into();
+                            }
+
+                            pix_mp
+                        },
+                    }
+                }
+                _ => bindings::v4l2_format__bindgen_ty_1 {
+                    pix: {
+                        if format.plane_fmt.len() > 1 {
+                            return Err(Self::Error::TooManyPlanes(format.plane_fmt.len()));
+                        }
+
+                        let (bytesperline, sizeimage) = if !format.plane_fmt.is_empty() {
+                            (
+                                format.plane_fmt[0].bytesperline,
+                                format.plane_fmt[0].sizeimage,
+                            )
+                        } else {
+                            Default::default()
+                        };
+
+                        bindings::v4l2_pix_format {
+                            width: format.width,
+                            height: format.height,
+                            pixelformat: format.pixelformat.into(),
+                            bytesperline,
+                            sizeimage,
+                            ..Default::default()
+                        }
+                    },
+                },
+            },
+        })
+    }
+}
+
+impl From<&PlaneLayout> for bindings::v4l2_plane_pix_format {
+    fn from(plane: &PlaneLayout) -> Self {
+        bindings::v4l2_plane_pix_format {
+            sizeimage: plane.sizeimage,
+            bytesperline: plane.bytesperline,
+            ..Default::default()
+        }
+    }
+}
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::v4l2_format;
+    nix::ioctl_readwrite!(vidioc_g_fmt, b'V', 4, v4l2_format);
+    nix::ioctl_readwrite!(vidioc_s_fmt, b'V', 5, v4l2_format);
+    nix::ioctl_readwrite!(vidioc_try_fmt, b'V', 64, v4l2_format);
+}
+
+#[derive(Debug, Error)]
+pub enum GFmtError {
+    #[error("error while converting from V4L2 format")]
+    FromV4L2FormatConversionError,
+    #[error("invalid buffer type requested")]
+    InvalidBufferType,
+    #[error("unexpected ioctl error: {0}")]
+    IoctlError(nix::Error),
+}
+
+impl From<GFmtError> for Errno {
+    fn from(err: GFmtError) -> Self {
+        match err {
+            GFmtError::FromV4L2FormatConversionError => Errno::EINVAL,
+            GFmtError::InvalidBufferType => Errno::EINVAL,
+            GFmtError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_G_FMT` ioctl.
+pub fn g_fmt<O: TryFrom<v4l2_format>>(fd: &impl AsRawFd, queue: QueueType) -> Result<O, GFmtError> {
+    let mut fmt = v4l2_format {
+        type_: queue as u32,
+        ..Default::default()
+    };
+
+    match unsafe { ioctl::vidioc_g_fmt(fd.as_raw_fd(), &mut fmt) } {
+        Ok(_) => Ok(fmt
+            .try_into()
+            .map_err(|_| GFmtError::FromV4L2FormatConversionError)?),
+        Err(Errno::EINVAL) => Err(GFmtError::InvalidBufferType),
+        Err(e) => Err(GFmtError::IoctlError(e)),
+    }
+}
+
+#[derive(Debug, Error)]
+pub enum SFmtError {
+    #[error("error while converting from V4L2 format")]
+    FromV4L2FormatConversionError,
+    #[error("error while converting to V4L2 format")]
+    ToV4L2FormatConversionError,
+    #[error("invalid buffer type requested")]
+    InvalidBufferType,
+    #[error("device currently busy")]
+    DeviceBusy,
+    #[error("ioctl error: {0}")]
+    IoctlError(nix::Error),
+}
+
+impl From<SFmtError> for Errno {
+    fn from(err: SFmtError) -> Self {
+        match err {
+            SFmtError::FromV4L2FormatConversionError => Errno::EINVAL,
+            SFmtError::ToV4L2FormatConversionError => Errno::EINVAL,
+            SFmtError::InvalidBufferType => Errno::EINVAL,
+            SFmtError::DeviceBusy => Errno::EBUSY,
+            SFmtError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_S_FMT` ioctl.
+pub fn s_fmt<I: TryInto<v4l2_format>, O: TryFrom<v4l2_format>>(
+    fd: &mut impl AsRawFd,
+    format: I,
+) -> Result<O, SFmtError> {
+    let mut fmt: v4l2_format = format
+        .try_into()
+        .map_err(|_| SFmtError::ToV4L2FormatConversionError)?;
+
+    match unsafe { ioctl::vidioc_s_fmt(fd.as_raw_fd(), &mut fmt) } {
+        Ok(_) => Ok(fmt
+            .try_into()
+            .map_err(|_| SFmtError::FromV4L2FormatConversionError)?),
+        Err(Errno::EINVAL) => Err(SFmtError::InvalidBufferType),
+        Err(Errno::EBUSY) => Err(SFmtError::DeviceBusy),
+        Err(e) => Err(SFmtError::IoctlError(e)),
+    }
+}
+
+#[derive(Debug, Error)]
+pub enum TryFmtError {
+    #[error("error while converting from V4L2 format")]
+    FromV4L2FormatConversionError,
+    #[error("error while converting to V4L2 format")]
+    ToV4L2FormatConversionError,
+    #[error("invalid buffer type requested")]
+    InvalidBufferType,
+    #[error("ioctl error: {0}")]
+    IoctlError(nix::Error),
+}
+
+impl From<TryFmtError> for Errno {
+    fn from(err: TryFmtError) -> Self {
+        match err {
+            TryFmtError::FromV4L2FormatConversionError => Errno::EINVAL,
+            TryFmtError::ToV4L2FormatConversionError => Errno::EINVAL,
+            TryFmtError::InvalidBufferType => Errno::EINVAL,
+            TryFmtError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_TRY_FMT` ioctl.
+pub fn try_fmt<I: TryInto<v4l2_format>, O: TryFrom<v4l2_format>>(
+    fd: &impl AsRawFd,
+    format: I,
+) -> Result<O, TryFmtError> {
+    let mut fmt: v4l2_format = format
+        .try_into()
+        .map_err(|_| TryFmtError::ToV4L2FormatConversionError)?;
+
+    match unsafe { ioctl::vidioc_try_fmt(fd.as_raw_fd(), &mut fmt) } {
+        Ok(_) => Ok(fmt
+            .try_into()
+            .map_err(|_| TryFmtError::FromV4L2FormatConversionError)?),
+        Err(Errno::EINVAL) => Err(TryFmtError::InvalidBufferType),
+        Err(e) => Err(TryFmtError::IoctlError(e)),
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use std::convert::TryInto;
+
+    #[test]
+    // Convert from Format to multi-planar v4l2_format and back.
+    fn mplane_to_v4l2_format() {
+        // This is not a real format but let us use unique values per field.
+        let mplane = Format {
+            width: 632,
+            height: 480,
+            pixelformat: b"NM12".into(),
+            plane_fmt: vec![
+                PlaneLayout {
+                    sizeimage: 307200,
+                    bytesperline: 640,
+                },
+                PlaneLayout {
+                    sizeimage: 153600,
+                    bytesperline: 320,
+                },
+                PlaneLayout {
+                    sizeimage: 76800,
+                    bytesperline: 160,
+                },
+            ],
+        };
+        let v4l2_format = v4l2_format {
+            ..(QueueType::VideoCaptureMplane, &mplane).try_into().unwrap()
+        };
+        let mplane2: Format = v4l2_format.try_into().unwrap();
+        assert_eq!(mplane, mplane2);
+    }
+
+    #[test]
+    // Convert from Format to single-planar v4l2_format and back.
+    fn splane_to_v4l2_format() {
+        // This is not a real format but let us use unique values per field.
+        let splane = Format {
+            width: 632,
+            height: 480,
+            pixelformat: b"NV12".into(),
+            plane_fmt: vec![PlaneLayout {
+                sizeimage: 307200,
+                bytesperline: 640,
+            }],
+        };
+        // Conversion to/from single-planar format.
+        let v4l2_format = v4l2_format {
+            ..(QueueType::VideoCapture, &splane).try_into().unwrap()
+        };
+        let splane2: Format = v4l2_format.try_into().unwrap();
+        assert_eq!(splane, splane2);
+
+        // Trying to use a multi-planar format with the single-planar API should
+        // fail.
+        let mplane = Format {
+            width: 632,
+            height: 480,
+            pixelformat: b"NM12".into(),
+            // This is not a real format but let us use unique values per field.
+            plane_fmt: vec![
+                PlaneLayout {
+                    sizeimage: 307200,
+                    bytesperline: 640,
+                },
+                PlaneLayout {
+                    sizeimage: 153600,
+                    bytesperline: 320,
+                },
+                PlaneLayout {
+                    sizeimage: 76800,
+                    bytesperline: 160,
+                },
+            ],
+        };
+        assert_eq!(
+            TryInto::<v4l2_format>::try_into((QueueType::VideoCapture, &mplane)).err(),
+            Some(FormatConversionError::TooManyPlanes(3))
+        );
+    }
+}

libs/v4l2r/src/ioctl/g_parm.rs

@@ -0,0 +1,149 @@
+use std::os::unix::io::AsRawFd;
+
+use nix::errno::Errno;
+use thiserror::Error;
+
+use crate::bindings::v4l2_standard;
+use crate::bindings::v4l2_std_id;
+use crate::bindings::v4l2_streamparm;
+use crate::QueueType;
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::v4l2_standard;
+    use crate::bindings::v4l2_std_id;
+    use crate::bindings::v4l2_streamparm;
+
+    nix::ioctl_readwrite!(vidioc_g_parm, b'V', 21, v4l2_streamparm);
+    nix::ioctl_readwrite!(vidioc_s_parm, b'V', 22, v4l2_streamparm);
+    nix::ioctl_read!(vidioc_g_std, b'V', 23, v4l2_std_id);
+    nix::ioctl_write_ptr!(vidioc_s_std, b'V', 24, v4l2_std_id);
+    nix::ioctl_readwrite!(vidioc_enumstd, b'V', 25, v4l2_standard);
+    nix::ioctl_read!(vidioc_querystd, b'V', 63, v4l2_std_id);
+}
+
+#[derive(Debug, Error)]
+pub enum GParmError {
+    #[error("ioctl error: {0}")]
+    IoctlError(Errno),
+}
+
+impl From<GParmError> for Errno {
+    fn from(err: GParmError) -> Self {
+        match err {
+            GParmError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_G_PARM` ioctl.
+pub fn g_parm<O: From<v4l2_streamparm>>(
+    fd: &impl AsRawFd,
+    queue: QueueType,
+) -> Result<O, GParmError> {
+    let mut parm = v4l2_streamparm {
+        type_: queue as u32,
+        ..Default::default()
+    };
+
+    match unsafe { ioctl::vidioc_g_parm(fd.as_raw_fd(), &mut parm) } {
+        Ok(_) => Ok(O::from(parm)),
+        Err(e) => Err(GParmError::IoctlError(e)),
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_S_PARM` ioctl.
+pub fn s_parm<I: Into<v4l2_streamparm>, O: From<v4l2_streamparm>>(
+    fd: &impl AsRawFd,
+    parm: I,
+) -> Result<O, GParmError> {
+    let mut parm = parm.into();
+
+    match unsafe { ioctl::vidioc_s_parm(fd.as_raw_fd(), &mut parm) } {
+        Ok(_) => Ok(O::from(parm)),
+        Err(e) => Err(GParmError::IoctlError(e)),
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_G_STD` ioctl.
+pub fn g_std<O: From<v4l2_std_id>>(fd: &impl AsRawFd) -> Result<O, GParmError> {
+    let mut std_id: v4l2_std_id = 0;
+
+    match unsafe { ioctl::vidioc_g_std(fd.as_raw_fd(), &mut std_id) } {
+        Ok(_) => Ok(O::from(std_id)),
+        Err(e) => Err(GParmError::IoctlError(e)),
+    }
+}
+
+#[derive(Debug, Error)]
+pub enum SStdError {
+    #[error("unsupported standard requested")]
+    Unsupported,
+    #[error("ioctl error: {0}")]
+    IoctlError(Errno),
+}
+
+impl From<SStdError> for Errno {
+    fn from(err: SStdError) -> Self {
+        match err {
+            SStdError::Unsupported => Errno::EINVAL,
+            SStdError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_S_STD` ioctl.
+pub fn s_std<I: Into<v4l2_std_id>>(fd: &impl AsRawFd, std_id: I) -> Result<(), SStdError> {
+    let std_id = std_id.into();
+
+    match unsafe { ioctl::vidioc_s_std(fd.as_raw_fd(), &std_id) } {
+        Ok(_) => Ok(()),
+        Err(Errno::EINVAL) => Err(SStdError::Unsupported),
+        Err(e) => Err(SStdError::IoctlError(e)),
+    }
+}
+
+#[derive(Debug, Error)]
+pub enum EnumStdError {
+    #[error("requested index is out of bounds")]
+    OutOfBounds,
+    #[error("standard video timings are not supported for this input or output")]
+    Unsupported,
+    #[error("ioctl error: {0}")]
+    IoctlError(Errno),
+}
+
+impl From<EnumStdError> for Errno {
+    fn from(err: EnumStdError) -> Self {
+        match err {
+            EnumStdError::OutOfBounds => Errno::EINVAL,
+            EnumStdError::Unsupported => Errno::ENODATA,
+            EnumStdError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_ENUMSTD` ioctl.
+pub fn enumstd<O: From<v4l2_standard>>(fd: &impl AsRawFd, index: u32) -> Result<O, EnumStdError> {
+    let mut standard = v4l2_standard {
+        index,
+        ..Default::default()
+    };
+
+    match unsafe { ioctl::vidioc_enumstd(fd.as_raw_fd(), &mut standard) } {
+        Ok(_) => Ok(O::from(standard)),
+        Err(Errno::EINVAL) => Err(EnumStdError::OutOfBounds),
+        Err(Errno::ENODATA) => Err(EnumStdError::Unsupported),
+        Err(e) => Err(EnumStdError::IoctlError(e)),
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_QUERYSTD` ioctl.
+pub fn querystd<O: From<v4l2_std_id>>(fd: &impl AsRawFd) -> Result<O, GParmError> {
+    let mut std_id: v4l2_std_id = 0;
+
+    match unsafe { ioctl::vidioc_querystd(fd.as_raw_fd(), &mut std_id) } {
+        Ok(_) => Ok(O::from(std_id)),
+        Err(e) => Err(GParmError::IoctlError(e)),
+    }
+}

libs/v4l2r/src/ioctl/g_selection.rs

@@ -0,0 +1,130 @@
+use std::os::unix::io::AsRawFd;
+
+use bitflags::bitflags;
+use enumn::N;
+use nix::errno::Errno;
+use thiserror::Error;
+
+use crate::bindings;
+use crate::bindings::v4l2_rect;
+use crate::bindings::v4l2_selection;
+
+#[derive(Debug, N, Clone, Copy, PartialEq, Eq)]
+#[repr(u32)]
+pub enum SelectionType {
+    Capture = bindings::v4l2_buf_type_V4L2_BUF_TYPE_VIDEO_CAPTURE,
+    Output = bindings::v4l2_buf_type_V4L2_BUF_TYPE_VIDEO_OUTPUT,
+}
+
+#[derive(Debug, N, Clone, Copy, PartialEq, Eq)]
+#[repr(u32)]
+pub enum SelectionTarget {
+    Crop = bindings::V4L2_SEL_TGT_CROP,
+    CropDefault = bindings::V4L2_SEL_TGT_CROP_DEFAULT,
+    CropBounds = bindings::V4L2_SEL_TGT_CROP_BOUNDS,
+    NativeSize = bindings::V4L2_SEL_TGT_NATIVE_SIZE,
+    Compose = bindings::V4L2_SEL_TGT_COMPOSE,
+    ComposeDefault = bindings::V4L2_SEL_TGT_COMPOSE_DEFAULT,
+    ComposeBounds = bindings::V4L2_SEL_TGT_COMPOSE_BOUNDS,
+    ComposePadded = bindings::V4L2_SEL_TGT_COMPOSE_PADDED,
+}
+
+bitflags! {
+    #[derive(Clone, Copy, Debug)]
+    pub struct SelectionFlags: u32 {
+        const GE = bindings::V4L2_SEL_FLAG_GE;
+        const LE = bindings::V4L2_SEL_FLAG_LE;
+        const KEEP_CONFIG = bindings::V4L2_SEL_FLAG_KEEP_CONFIG;
+    }
+}
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::v4l2_selection;
+    nix::ioctl_readwrite!(vidioc_g_selection, b'V', 94, v4l2_selection);
+    nix::ioctl_readwrite!(vidioc_s_selection, b'V', 95, v4l2_selection);
+}
+
+#[derive(Debug, Error)]
+pub enum GSelectionError {
+    #[error("invalid type or target requested")]
+    Invalid,
+    #[error("ioctl error: {0}")]
+    IoctlError(Errno),
+}
+
+impl From<GSelectionError> for Errno {
+    fn from(err: GSelectionError) -> Self {
+        match err {
+            GSelectionError::Invalid => Errno::EINVAL,
+            GSelectionError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_G_SELECTION` ioctl.
+pub fn g_selection<R: From<v4l2_rect>>(
+    fd: &impl AsRawFd,
+    selection: SelectionType,
+    target: SelectionTarget,
+) -> Result<R, GSelectionError> {
+    let mut sel = v4l2_selection {
+        type_: selection as u32,
+        target: target as u32,
+        ..Default::default()
+    };
+
+    match unsafe { ioctl::vidioc_g_selection(fd.as_raw_fd(), &mut sel) } {
+        Ok(_) => Ok(R::from(sel.r)),
+        Err(Errno::EINVAL) => Err(GSelectionError::Invalid),
+        Err(e) => Err(GSelectionError::IoctlError(e)),
+    }
+}
+
+#[derive(Debug, Error)]
+pub enum SSelectionError {
+    #[error("invalid type or target requested")]
+    Invalid,
+    #[error("invalid range requested")]
+    InvalidRange,
+    #[error("cannot change selection rectangle currently")]
+    Busy,
+    #[error("ioctl error: {0}")]
+    IoctlError(nix::Error),
+}
+
+impl From<SSelectionError> for Errno {
+    fn from(err: SSelectionError) -> Self {
+        match err {
+            SSelectionError::Invalid => Errno::EINVAL,
+            SSelectionError::InvalidRange => Errno::ERANGE,
+            SSelectionError::Busy => Errno::EBUSY,
+            SSelectionError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_S_SELECTION` ioctl.
+pub fn s_selection<RI: Into<v4l2_rect>, RO: From<v4l2_rect>>(
+    fd: &impl AsRawFd,
+    selection: SelectionType,
+    target: SelectionTarget,
+    rect: RI,
+    flags: SelectionFlags,
+) -> Result<RO, SSelectionError> {
+    let mut sel = v4l2_selection {
+        type_: selection as u32,
+        target: target as u32,
+        flags: flags.bits(),
+        r: rect.into(),
+        ..Default::default()
+    };
+
+    match unsafe { ioctl::vidioc_s_selection(fd.as_raw_fd(), &mut sel) } {
+        Ok(_) => Ok(RO::from(sel.r)),
+        Err(Errno::EINVAL) => Err(SSelectionError::Invalid),
+        Err(Errno::ERANGE) => Err(SSelectionError::InvalidRange),
+        Err(Errno::EBUSY) => Err(SSelectionError::Busy),
+        Err(e) => Err(SSelectionError::IoctlError(e)),
+    }
+}

libs/v4l2r/src/ioctl/mmap.rs

@@ -0,0 +1,117 @@
+use core::num::NonZeroUsize;
+use std::{
+    cmp::{max, min},
+    ops::Deref,
+    ptr::NonNull,
+    slice,
+};
+use std::{ops::DerefMut, os::unix::io::AsFd};
+
+use log::error;
+use nix::{errno::Errno, libc::off_t, sys::mman};
+use thiserror::Error;
+
+pub struct PlaneMapping {
+    // A mapping remains valid until we munmap it, that is, until the
+    // PlaneMapping object is deleted. Hence the static lifetime.
+    pub data: &'static mut [u8],
+
+    start: usize,
+    end: usize,
+}
+
+impl PlaneMapping {
+    pub fn size(&self) -> usize {
+        self.end - self.start
+    }
+
+    pub fn restrict(mut self, start: usize, end: usize) -> Self {
+        self.start = max(self.start, start);
+        self.end = min(self.end, end);
+
+        self
+    }
+}
+
+impl AsRef<[u8]> for PlaneMapping {
+    fn as_ref(&self) -> &[u8] {
+        &self.data[self.start..self.end]
+    }
+}
+
+impl AsMut<[u8]> for PlaneMapping {
+    fn as_mut(&mut self) -> &mut [u8] {
+        &mut self.data[self.start..self.end]
+    }
+}
+
+impl Deref for PlaneMapping {
+    type Target = [u8];
+
+    fn deref(&self) -> &Self::Target {
+        &self.data[self.start..self.end]
+    }
+}
+
+impl DerefMut for PlaneMapping {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.data[self.start..self.end]
+    }
+}
+
+impl Drop for PlaneMapping {
+    fn drop(&mut self) {
+        // Safe because the pointer and length were constructed in mmap() and
+        // are always valid.
+        unsafe {
+            mman::munmap(
+                NonNull::new_unchecked(self.data.as_mut_ptr().cast()),
+                self.data.len(),
+            )
+        }
+        .unwrap_or_else(|e| {
+            error!("Error while unmapping plane: {}", e);
+        });
+    }
+}
+
+#[derive(Debug, Error)]
+pub enum MmapError {
+    #[error("provided length was 0")]
+    ZeroLength,
+    #[error("ioctl error: {0}")]
+    IoctlError(#[from] Errno),
+}
+
+impl From<MmapError> for Errno {
+    fn from(err: MmapError) -> Self {
+        match err {
+            MmapError::ZeroLength => Errno::EINVAL,
+            MmapError::IoctlError(e) => e,
+        }
+    }
+}
+
+// TODO should be unsafe because the mapping can be used after a buffer is queued?
+// Or not, since this cannot cause a crash...
+pub fn mmap(fd: &impl AsFd, mem_offset: u32, length: u32) -> Result<PlaneMapping, MmapError> {
+    let non_zero_length = NonZeroUsize::new(length as usize).ok_or(MmapError::ZeroLength)?;
+    let data = unsafe {
+        mman::mmap(
+            None,
+            non_zero_length,
+            mman::ProtFlags::PROT_READ | mman::ProtFlags::PROT_WRITE,
+            mman::MapFlags::MAP_SHARED,
+            fd,
+            mem_offset as off_t,
+        )
+    }?;
+
+    Ok(PlaneMapping {
+        // Safe because we know the pointer is valid and has enough data mapped
+        // to cover the length.
+        data: unsafe { slice::from_raw_parts_mut(data.as_ptr().cast(), length as usize) },
+        start: 0,
+        end: length as usize,
+    })
+}

libs/v4l2r/src/ioctl/qbuf.rs

@@ -0,0 +1,197 @@
+//! Safe wrapper for the VIDIOC_(D)QBUF and VIDIOC_QUERYBUF ioctls.
+use nix::errno::Errno;
+use nix::libc::{suseconds_t, time_t};
+use nix::sys::time::{TimeVal, TimeValLike};
+use std::convert::TryFrom;
+use std::fmt::Debug;
+use std::os::unix::io::AsRawFd;
+use thiserror::Error;
+
+use crate::bindings;
+use crate::ioctl::ioctl_and_convert;
+use crate::ioctl::BufferFlags;
+use crate::ioctl::IoctlConvertError;
+use crate::ioctl::IoctlConvertResult;
+use crate::ioctl::UncheckedV4l2Buffer;
+use crate::memory::Memory;
+use crate::memory::PlaneHandle;
+use crate::QueueType;
+
+#[derive(Debug, Error)]
+pub enum QBufIoctlError {
+    #[error("invalid number of planes specified for the buffer: got {0}, expected {1}")]
+    NumPlanesMismatch(usize, usize),
+    #[error("data offset specified while using the single-planar API")]
+    DataOffsetNotSupported,
+    #[error("unexpected ioctl error: {0}")]
+    Other(Errno),
+}
+
+impl From<Errno> for QBufIoctlError {
+    fn from(errno: Errno) -> Self {
+        Self::Other(errno)
+    }
+}
+
+impl From<QBufIoctlError> for Errno {
+    fn from(err: QBufIoctlError) -> Self {
+        match err {
+            QBufIoctlError::NumPlanesMismatch(_, _) => Errno::EINVAL,
+            QBufIoctlError::DataOffsetNotSupported => Errno::EINVAL,
+            QBufIoctlError::Other(e) => e,
+        }
+    }
+}
+
+/// Representation of a single plane of a V4L2 buffer.
+pub struct QBufPlane(pub bindings::v4l2_plane);
+
+impl QBufPlane {
+    // TODO remove as this is not safe - we should always specify a handle.
+    pub fn new(bytes_used: usize) -> Self {
+        QBufPlane(bindings::v4l2_plane {
+            bytesused: bytes_used as u32,
+            data_offset: 0,
+            ..Default::default()
+        })
+    }
+
+    pub fn new_from_handle<H: PlaneHandle>(handle: &H, bytes_used: usize) -> Self {
+        let mut plane = Self::new(bytes_used);
+        handle.fill_v4l2_plane(&mut plane.0);
+        plane
+    }
+}
+
+impl Debug for QBufPlane {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("QBufPlane")
+            .field("bytesused", &self.0.bytesused)
+            .field("data_offset", &self.0.data_offset)
+            .finish()
+    }
+}
+
+/// Contains all the information that can be passed to the `qbuf` ioctl.
+// TODO Change this to contain a v4l2_buffer, and create constructors/methods
+// to change it? Then during qbuf we just need to set m.planes to planes
+// (after resizing it to 8) and we are good to use it as-is.
+// We could even turn the trait into AsRef<v4l2_buffer> for good measure.
+#[derive(Debug)]
+pub struct QBuffer<H: PlaneHandle> {
+    index: u32,
+    queue: QueueType,
+    pub flags: BufferFlags,
+    pub field: u32,
+    pub sequence: u32,
+    pub timestamp: TimeVal,
+    pub planes: Vec<QBufPlane>,
+    pub _h: std::marker::PhantomData<H>,
+}
+
+impl<H: PlaneHandle> QBuffer<H> {
+    pub fn new(queue: QueueType, index: u32) -> Self {
+        QBuffer {
+            index,
+            queue,
+            flags: Default::default(),
+            field: Default::default(),
+            sequence: Default::default(),
+            timestamp: TimeVal::zero(),
+            planes: Vec::new(),
+            _h: std::marker::PhantomData,
+        }
+    }
+}
+
+impl<H: PlaneHandle> QBuffer<H> {
+    pub fn set_timestamp(mut self, sec: time_t, usec: suseconds_t) -> Self {
+        self.timestamp = TimeVal::new(sec, usec);
+        self
+    }
+}
+
+impl<H: PlaneHandle> From<QBuffer<H>> for UncheckedV4l2Buffer {
+    fn from(qbuf: QBuffer<H>) -> Self {
+        let mut v4l2_buf = UncheckedV4l2Buffer::new_for_querybuf(qbuf.queue, Some(qbuf.index));
+        v4l2_buf.0.index = qbuf.index;
+        v4l2_buf.0.type_ = qbuf.queue as u32;
+        v4l2_buf.0.memory = H::Memory::MEMORY_TYPE as u32;
+        v4l2_buf.0.flags = qbuf.flags.bits();
+        v4l2_buf.0.field = qbuf.field;
+        v4l2_buf.0.sequence = qbuf.sequence;
+        v4l2_buf.0.timestamp.tv_sec = qbuf.timestamp.tv_sec();
+        v4l2_buf.0.timestamp.tv_usec = qbuf.timestamp.tv_usec();
+        if let Some(planes) = &mut v4l2_buf.1 {
+            for (dst_plane, src_plane) in planes.iter_mut().zip(qbuf.planes.into_iter()) {
+                *dst_plane = src_plane.0;
+            }
+        } else {
+            let plane = &qbuf.planes[0];
+
+            v4l2_buf.0.length = plane.0.length;
+            v4l2_buf.0.bytesused = plane.0.bytesused;
+            v4l2_buf.0.m = (&plane.0.m, H::Memory::MEMORY_TYPE).into();
+        }
+
+        v4l2_buf
+    }
+}
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::v4l2_buffer;
+    nix::ioctl_readwrite!(vidioc_querybuf, b'V', 9, v4l2_buffer);
+    nix::ioctl_readwrite!(vidioc_qbuf, b'V', 15, v4l2_buffer);
+    nix::ioctl_readwrite!(vidioc_dqbuf, b'V', 17, v4l2_buffer);
+    nix::ioctl_readwrite!(vidioc_prepare_buf, b'V', 93, v4l2_buffer);
+}
+
+pub type QBufError<CE> = IoctlConvertError<QBufIoctlError, CE>;
+pub type QBufResult<O, CE> = IoctlConvertResult<O, QBufIoctlError, CE>;
+
+/// Safe wrapper around the `VIDIOC_QBUF` ioctl.
+///
+/// TODO: `qbuf` should be unsafe! The following invariants need to be guaranteed
+/// by the caller:
+///
+/// For MMAP buffers, any mapping must not be accessed by the caller (or any
+/// mapping must be unmapped before queueing?). Also if the buffer has been
+/// DMABUF-exported, its consumers must likewise not access it.
+///
+/// For DMABUF buffers, the FD must not be duplicated and accessed anywhere else.
+///
+/// For USERPTR buffers, things are most tricky. Not only must the data not be
+/// accessed by anyone else, the caller also needs to guarantee that the backing
+/// memory won't be freed until the corresponding buffer is returned by either
+/// `dqbuf` or `streamoff`.
+pub fn qbuf<I, O>(fd: &impl AsRawFd, buffer: I) -> QBufResult<O, O::Error>
+where
+    I: Into<UncheckedV4l2Buffer>,
+    O: TryFrom<UncheckedV4l2Buffer>,
+    O::Error: std::fmt::Debug,
+{
+    let mut v4l2_buf: UncheckedV4l2Buffer = buffer.into();
+
+    ioctl_and_convert(
+        unsafe { ioctl::vidioc_qbuf(fd.as_raw_fd(), v4l2_buf.as_mut()) }
+            .map(|_| v4l2_buf)
+            .map_err(Into::into),
+    )
+}
+
+/// Safe wrapper around the `VIDIOC_PREPARE_BUF` ioctl.
+pub fn prepare_buf<I, O>(fd: &impl AsRawFd, buffer: I) -> QBufResult<O, O::Error>
+where
+    I: Into<UncheckedV4l2Buffer>,
+    O: TryFrom<UncheckedV4l2Buffer>,
+    O::Error: std::fmt::Debug,
+{
+    let mut v4l2_buf: UncheckedV4l2Buffer = buffer.into();
+
+    ioctl_and_convert(
+        unsafe { ioctl::vidioc_prepare_buf(fd.as_raw_fd(), v4l2_buf.as_mut()) }
+            .map(|_| v4l2_buf)
+            .map_err(Into::into),
+    )
+}

libs/v4l2r/src/ioctl/querybuf.rs

@@ -0,0 +1,113 @@
+use std::convert::Infallible;
+use std::convert::TryFrom;
+use std::os::unix::io::AsRawFd;
+
+use nix::errno::Errno;
+use thiserror::Error;
+
+use crate::ioctl::ioctl_and_convert;
+use crate::ioctl::BufferFlags;
+use crate::ioctl::IoctlConvertError;
+use crate::ioctl::IoctlConvertResult;
+use crate::ioctl::UncheckedV4l2Buffer;
+use crate::QueueType;
+
+#[derive(Debug)]
+pub struct QueryBufPlane {
+    /// Offset to pass to `mmap()` in order to obtain a mapping for this plane.
+    pub mem_offset: u32,
+    /// Length of this plane.
+    pub length: u32,
+}
+
+/// Contains information about a buffer's layout, as obtained from [`crate::ioctl::querybuf`].
+///
+/// It is a subset of [`crate::ioctl::V4l2Buffer`], only more convenient on occasion because its
+/// conversion from an unchecked v4l2_buffer cannot fail.
+///
+/// Single-planar buffers have one entry in [`planes`] representing the layout of their unique
+/// plane.
+#[derive(Debug)]
+pub struct QueryBuffer {
+    pub index: usize,
+    pub flags: BufferFlags,
+    pub planes: Vec<QueryBufPlane>,
+}
+
+impl TryFrom<UncheckedV4l2Buffer> for QueryBuffer {
+    type Error = Infallible;
+
+    fn try_from(buffer: UncheckedV4l2Buffer) -> Result<Self, Self::Error> {
+        let v4l2_buf = buffer.0;
+        let planes = match buffer.1 {
+            None => vec![QueryBufPlane {
+                mem_offset: unsafe { v4l2_buf.m.offset },
+                length: v4l2_buf.length,
+            }],
+            Some(v4l2_planes) => v4l2_planes
+                .iter()
+                .take(v4l2_buf.length as usize)
+                .map(|v4l2_plane| QueryBufPlane {
+                    mem_offset: unsafe { v4l2_plane.m.mem_offset },
+                    length: v4l2_plane.length,
+                })
+                .collect(),
+        };
+
+        Ok(QueryBuffer {
+            index: v4l2_buf.index as usize,
+            flags: BufferFlags::from_bits_truncate(v4l2_buf.flags),
+            planes,
+        })
+    }
+}
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::v4l2_buffer;
+    nix::ioctl_readwrite!(vidioc_querybuf, b'V', 9, v4l2_buffer);
+}
+
+#[derive(Debug, Error)]
+pub enum QueryBufIoctlError {
+    #[error("unsupported queue or out-of-bounds index")]
+    InvalidInput,
+    #[error("unexpected ioctl error: {0}")]
+    Other(Errno),
+}
+
+impl From<Errno> for QueryBufIoctlError {
+    fn from(err: Errno) -> Self {
+        match err {
+            Errno::EINVAL => QueryBufIoctlError::InvalidInput,
+            e => QueryBufIoctlError::Other(e),
+        }
+    }
+}
+
+impl From<QueryBufIoctlError> for Errno {
+    fn from(err: QueryBufIoctlError) -> Self {
+        match err {
+            QueryBufIoctlError::InvalidInput => Errno::EINVAL,
+            QueryBufIoctlError::Other(e) => e,
+        }
+    }
+}
+
+pub type QueryBufError<CE> = IoctlConvertError<QueryBufIoctlError, CE>;
+pub type QueryBufResult<O, CE> = IoctlConvertResult<O, QueryBufIoctlError, CE>;
+
+/// Safe wrapper around the `VIDIOC_QUERYBUF` ioctl.
+pub fn querybuf<O>(fd: &impl AsRawFd, queue: QueueType, index: usize) -> QueryBufResult<O, O::Error>
+where
+    O: TryFrom<UncheckedV4l2Buffer>,
+    O::Error: std::fmt::Debug,
+{
+    let mut v4l2_buf = UncheckedV4l2Buffer::new_for_querybuf(queue, Some(index as u32));
+
+    ioctl_and_convert(
+        unsafe { ioctl::vidioc_querybuf(fd.as_raw_fd(), v4l2_buf.as_mut()) }
+            .map(|_| v4l2_buf)
+            .map_err(Into::into),
+    )
+}

libs/v4l2r/src/ioctl/querycap.rs

@@ -0,0 +1,136 @@
+//! Safe wrapper for the `VIDIOC_QUERYCAP` ioctl.
+use super::string_from_cstr;
+use crate::bindings;
+use crate::bindings::v4l2_capability;
+use bitflags::bitflags;
+use nix::errno::Errno;
+use std::fmt;
+use std::os::unix::io::AsRawFd;
+use thiserror::Error;
+
+bitflags! {
+    /// Flags returned by the `VIDIOC_QUERYCAP` ioctl into the `capabilities`
+    /// or `device_capabilities` field of `v4l2_capability`.
+    #[derive(Clone, Copy, Debug)]
+    pub struct Capabilities: u32 {
+        const VIDEO_CAPTURE = bindings::V4L2_CAP_VIDEO_CAPTURE;
+        const VIDEO_OUTPUT = bindings::V4L2_CAP_VIDEO_OUTPUT;
+        const VIDEO_OVERLAY = bindings::V4L2_CAP_VIDEO_OVERLAY;
+        const VBI_CAPTURE = bindings::V4L2_CAP_VBI_CAPTURE;
+        const VBI_OUTPUT = bindings::V4L2_CAP_VBI_OUTPUT;
+        const SLICED_VBI_CAPTURE = bindings::V4L2_CAP_SLICED_VBI_CAPTURE;
+        const SLICED_VBI_OUTPUT = bindings::V4L2_CAP_SLICED_VBI_OUTPUT;
+        const RDS_CAPTURE = bindings::V4L2_CAP_RDS_CAPTURE;
+        const VIDEO_OUTPUT_OVERLAY = bindings::V4L2_CAP_VIDEO_OUTPUT_OVERLAY;
+        const HW_FREQ_SEEK = bindings::V4L2_CAP_HW_FREQ_SEEK;
+        const RDS_OUTPUT = bindings::V4L2_CAP_RDS_OUTPUT;
+
+        const VIDEO_CAPTURE_MPLANE = bindings::V4L2_CAP_VIDEO_CAPTURE_MPLANE;
+        const VIDEO_OUTPUT_MPLANE = bindings::V4L2_CAP_VIDEO_OUTPUT_MPLANE;
+        const VIDEO_M2M_MPLANE = bindings::V4L2_CAP_VIDEO_M2M_MPLANE;
+        const VIDEO_M2M = bindings::V4L2_CAP_VIDEO_M2M;
+
+        const TUNER = bindings::V4L2_CAP_TUNER;
+        const AUDIO = bindings::V4L2_CAP_AUDIO;
+        const RADIO = bindings::V4L2_CAP_RADIO;
+        const MODULATOR = bindings::V4L2_CAP_MODULATOR;
+
+        const SDR_CAPTURE = bindings::V4L2_CAP_SDR_CAPTURE;
+        const EXT_PIX_FORMAT = bindings::V4L2_CAP_EXT_PIX_FORMAT;
+        const SDR_OUTPUT = bindings::V4L2_CAP_SDR_OUTPUT;
+        const META_CAPTURE = bindings::V4L2_CAP_META_CAPTURE;
+
+        const READWRITE = bindings::V4L2_CAP_READWRITE;
+        const ASYNCIO = bindings::V4L2_CAP_ASYNCIO;
+        const STREAMING = bindings::V4L2_CAP_STREAMING;
+        const META_OUTPUT = bindings::V4L2_CAP_META_OUTPUT;
+
+        const TOUCH = bindings::V4L2_CAP_TOUCH;
+
+        const DEVICE_CAPS = bindings::V4L2_CAP_DEVICE_CAPS;
+    }
+}
+
+impl fmt::Display for Capabilities {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Debug::fmt(self, f)
+    }
+}
+
+/// Used to get the capability flags from a `VIDIOC_QUERYCAP` ioctl.
+impl From<v4l2_capability> for Capabilities {
+    fn from(qcap: v4l2_capability) -> Self {
+        Capabilities::from_bits_truncate(qcap.capabilities)
+    }
+}
+
+/// Safe variant of the `v4l2_capability` struct, to be used with `querycap`.
+#[derive(Debug)]
+pub struct Capability {
+    pub driver: String,
+    pub card: String,
+    pub bus_info: String,
+    pub version: u32,
+    pub capabilities: Capabilities,
+    pub device_caps: Option<Capabilities>,
+}
+
+impl Capability {
+    /// Returns the set of capabilities of the hardware as a whole.
+    pub fn capabilities(&self) -> Capabilities {
+        self.capabilities
+    }
+
+    /// Returns the capabilities that apply to the currently opened V4L2 node.
+    pub fn device_caps(&self) -> Capabilities {
+        self.device_caps
+            .unwrap_or_else(|| self.capabilities.difference(Capabilities::DEVICE_CAPS))
+    }
+}
+
+impl From<v4l2_capability> for Capability {
+    fn from(qcap: v4l2_capability) -> Self {
+        Capability {
+            driver: string_from_cstr(&qcap.driver).unwrap_or_else(|_| "".into()),
+            card: string_from_cstr(&qcap.card).unwrap_or_else(|_| "".into()),
+            bus_info: string_from_cstr(&qcap.bus_info).unwrap_or_else(|_| "".into()),
+            version: qcap.version,
+            capabilities: Capabilities::from_bits_truncate(qcap.capabilities),
+            device_caps: if qcap.capabilities & bindings::V4L2_CAP_DEVICE_CAPS != 0 {
+                Some(Capabilities::from_bits_truncate(qcap.device_caps))
+            } else {
+                None
+            },
+        }
+    }
+}
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::v4l2_capability;
+    nix::ioctl_read!(vidioc_querycap, b'V', 0, v4l2_capability);
+}
+
+#[derive(Debug, Error)]
+pub enum QueryCapError {
+    #[error("ioctl error: {0}")]
+    IoctlError(Errno),
+}
+
+impl From<QueryCapError> for Errno {
+    fn from(err: QueryCapError) -> Self {
+        match err {
+            QueryCapError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_QUERYCAP` ioctl.
+pub fn querycap<T: From<v4l2_capability>>(fd: &impl AsRawFd) -> Result<T, QueryCapError> {
+    let mut qcap: v4l2_capability = Default::default();
+
+    match unsafe { ioctl::vidioc_querycap(fd.as_raw_fd(), &mut qcap) } {
+        Ok(_) => Ok(T::from(qcap)),
+        Err(e) => Err(QueryCapError::IoctlError(e)),
+    }
+}

libs/v4l2r/src/ioctl/reqbufs.rs

@@ -0,0 +1,162 @@
+//! Safe wrapper for the `VIDIOC_REQBUFS` ioctl.
+use crate::bindings;
+use crate::bindings::v4l2_create_buffers;
+use crate::bindings::v4l2_format;
+use crate::bindings::v4l2_requestbuffers;
+use crate::memory::MemoryType;
+use crate::QueueType;
+use bitflags::bitflags;
+use nix::{self, errno::Errno};
+use std::os::unix::io::AsRawFd;
+use thiserror::Error;
+
+bitflags! {
+    /// Flags returned by the `VIDIOC_REQBUFS` ioctl into the `capabilities`
+    /// field of `struct v4l2_requestbuffers`.
+    #[derive(Clone, Copy, Debug)]
+    pub struct BufferCapabilities: u32 {
+        const SUPPORTS_MMAP = bindings::V4L2_BUF_CAP_SUPPORTS_MMAP;
+        const SUPPORTS_USERPTR = bindings::V4L2_BUF_CAP_SUPPORTS_USERPTR;
+        const SUPPORTS_DMABUF = bindings::V4L2_BUF_CAP_SUPPORTS_DMABUF;
+        const SUPPORTS_REQUESTS = bindings::V4L2_BUF_CAP_SUPPORTS_REQUESTS;
+        const SUPPORTS_ORPHANED_BUFS = bindings::V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS;
+        const SUPPORTS_M2M_HOLD_CAPTURE_BUF = bindings::V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF;
+        const SUPPORTS_MMAP_CACHE_HINTS = bindings::V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS;
+    }
+}
+
+bitflags! {
+    /// Memory Consistency Flags passed to the `VIDIOC_REQBUFS` ioctl in the `flags`
+    /// field of `struct v4l2_requestbuffers`.
+    #[derive(Clone, Copy, Debug)]
+    pub struct MemoryConsistency: u8 {
+        const MEMORY_FLAG_NON_COHERENT = bindings::V4L2_MEMORY_FLAG_NON_COHERENT as u8;
+    }
+}
+
+impl From<v4l2_requestbuffers> for () {
+    fn from(_reqbufs: v4l2_requestbuffers) -> Self {}
+}
+
+/// In case we are just interested in the number of buffers that `reqbufs`
+/// created.
+impl From<v4l2_requestbuffers> for usize {
+    fn from(reqbufs: v4l2_requestbuffers) -> Self {
+        reqbufs.count as usize
+    }
+}
+
+/// If we just want to query the buffer capabilities.
+impl From<v4l2_requestbuffers> for BufferCapabilities {
+    fn from(reqbufs: v4l2_requestbuffers) -> Self {
+        BufferCapabilities::from_bits_truncate(reqbufs.capabilities)
+    }
+}
+
+/// Full result of the `reqbufs` ioctl.
+pub struct RequestBuffers {
+    pub count: u32,
+    pub capabilities: BufferCapabilities,
+    pub flags: MemoryConsistency,
+}
+
+impl From<v4l2_requestbuffers> for RequestBuffers {
+    fn from(reqbufs: v4l2_requestbuffers) -> Self {
+        RequestBuffers {
+            count: reqbufs.count,
+            capabilities: BufferCapabilities::from_bits_truncate(reqbufs.capabilities),
+            flags: MemoryConsistency::from_bits_truncate(reqbufs.flags),
+        }
+    }
+}
+
+#[doc(hidden)]
+mod ioctl {
+    use crate::bindings::v4l2_create_buffers;
+    use crate::bindings::v4l2_requestbuffers;
+
+    nix::ioctl_readwrite!(vidioc_reqbufs, b'V', 8, v4l2_requestbuffers);
+    nix::ioctl_readwrite!(vidioc_create_bufs, b'V', 92, v4l2_create_buffers);
+}
+
+#[derive(Debug, Error)]
+pub enum ReqbufsError {
+    #[error("invalid buffer ({0}) or memory type ({1:?}) requested")]
+    InvalidBufferType(QueueType, MemoryType),
+    #[error("ioctl error: {0}")]
+    IoctlError(nix::Error),
+}
+
+impl From<ReqbufsError> for Errno {
+    fn from(err: ReqbufsError) -> Self {
+        match err {
+            ReqbufsError::InvalidBufferType(_, _) => Errno::EINVAL,
+            ReqbufsError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_REQBUFS` ioctl.
+pub fn reqbufs<O: From<v4l2_requestbuffers>>(
+    fd: &impl AsRawFd,
+    queue: QueueType,
+    memory: MemoryType,
+    count: u32,
+    flags: MemoryConsistency,
+) -> Result<O, ReqbufsError> {
+    let mut reqbufs = v4l2_requestbuffers {
+        count,
+        type_: queue as u32,
+        memory: memory as u32,
+        flags: flags.bits(),
+        ..Default::default()
+    };
+
+    match unsafe { ioctl::vidioc_reqbufs(fd.as_raw_fd(), &mut reqbufs) } {
+        Ok(_) => Ok(O::from(reqbufs)),
+        Err(Errno::EINVAL) => Err(ReqbufsError::InvalidBufferType(queue, memory)),
+        Err(e) => Err(ReqbufsError::IoctlError(e)),
+    }
+}
+
+#[derive(Debug, Error)]
+pub enum CreateBufsError {
+    #[error("no memory available to allocate MMAP buffers")]
+    NoMem,
+    #[error("invalid format or memory type requested")]
+    Invalid,
+    #[error("ioctl error: {0}")]
+    IoctlError(nix::Error),
+}
+
+impl From<CreateBufsError> for Errno {
+    fn from(err: CreateBufsError) -> Self {
+        match err {
+            CreateBufsError::NoMem => Errno::ENOMEM,
+            CreateBufsError::Invalid => Errno::EINVAL,
+            CreateBufsError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_CREATE_BUFS` ioctl.
+pub fn create_bufs<F: Into<v4l2_format>, O: From<v4l2_create_buffers>>(
+    fd: &impl AsRawFd,
+    count: u32,
+    memory: MemoryType,
+    format: F,
+) -> Result<O, CreateBufsError> {
+    let mut create_bufs = v4l2_create_buffers {
+        count,
+        memory: memory as u32,
+        format: format.into(),
+        ..Default::default()
+    };
+
+    match unsafe { ioctl::vidioc_create_bufs(fd.as_raw_fd(), &mut create_bufs) } {
+        Ok(_) => Ok(O::from(create_bufs)),
+        Err(Errno::ENOMEM) => Err(CreateBufsError::NoMem),
+        Err(Errno::EINVAL) => Err(CreateBufsError::Invalid),
+        Err(e) => Err(CreateBufsError::IoctlError(e)),
+    }
+}

libs/v4l2r/src/ioctl/streamon.rs

@@ -0,0 +1,71 @@
+//! Safe wrapper for the `VIDIOC_STREAM(ON|OFF)` ioctls.
+use crate::QueueType;
+use nix::errno::Errno;
+use std::os::unix::io::AsRawFd;
+use thiserror::Error;
+
+#[doc(hidden)]
+mod ioctl {
+    nix::ioctl_write_ptr!(vidioc_streamon, b'V', 18, u32);
+    nix::ioctl_write_ptr!(vidioc_streamoff, b'V', 19, u32);
+}
+
+#[derive(Debug, Error)]
+pub enum StreamOnError {
+    #[error("queue type ({0}) not supported, or no buffers allocated or enqueued")]
+    InvalidQueue(QueueType),
+    #[error("invalid pad configuration")]
+    InvalidPadConfig,
+    #[error("invalid pipeline link configuration")]
+    InvalidPipelineConfig,
+    #[error("ioctl error: {0}")]
+    IoctlError(Errno),
+}
+
+impl From<StreamOnError> for Errno {
+    fn from(err: StreamOnError) -> Self {
+        match err {
+            StreamOnError::InvalidQueue(_) => Errno::EINVAL,
+            StreamOnError::InvalidPadConfig => Errno::EPIPE,
+            StreamOnError::InvalidPipelineConfig => Errno::ENOLINK,
+            StreamOnError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_STREAMON` ioctl.
+pub fn streamon(fd: &impl AsRawFd, queue: QueueType) -> Result<(), StreamOnError> {
+    match unsafe { ioctl::vidioc_streamon(fd.as_raw_fd(), &(queue as u32)) } {
+        Ok(_) => Ok(()),
+        Err(Errno::EINVAL) => Err(StreamOnError::InvalidQueue(queue)),
+        Err(Errno::EPIPE) => Err(StreamOnError::InvalidPadConfig),
+        Err(Errno::ENOLINK) => Err(StreamOnError::InvalidPipelineConfig),
+        Err(e) => Err(StreamOnError::IoctlError(e)),
+    }
+}
+
+#[derive(Debug, Error)]
+pub enum StreamOffError {
+    #[error("queue type not supported")]
+    InvalidQueue,
+    #[error("ioctl error: {0}")]
+    IoctlError(Errno),
+}
+
+impl From<StreamOffError> for Errno {
+    fn from(err: StreamOffError) -> Self {
+        match err {
+            StreamOffError::InvalidQueue => Errno::EINVAL,
+            StreamOffError::IoctlError(e) => e,
+        }
+    }
+}
+
+/// Safe wrapper around the `VIDIOC_STREAMOFF` ioctl.
+pub fn streamoff(fd: &impl AsRawFd, queue: QueueType) -> Result<(), StreamOffError> {
+    match unsafe { ioctl::vidioc_streamoff(fd.as_raw_fd(), &(queue as u32)) } {
+        Ok(_) => Ok(()),
+        Err(Errno::EINVAL) => Err(StreamOffError::InvalidQueue),
+        Err(e) => Err(StreamOffError::IoctlError(e)),
+    }
+}

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)),
+    }
+}

libs/v4l2r/src/lib.rs

@@ -0,0 +1,496 @@
+//! This library provides the V4L2 pieces One-KVM needs for video capture:
+//!
+//! * The `ioctl` module provides direct, thin wrappers over the V4L2 ioctls
+//!   with added safety. Note that "safety" here is in terms of memory safety:
+//!   this layer won't guard against passing invalid data that the ioctls will
+//!   reject - it just makes sure that data passed from and to the kernel can
+//!   be accessed safely. Since this is a 1:1 mapping over the V4L2 ioctls,
+//!   working at this level is a bit laborious, although more comfortable than
+//!   doing the same in C.
+//!
+//! The upstream v4l2r crate also contains high-level decoder/encoder and C FFI
+//! layers. This vendored copy intentionally excludes those pieces and keeps the
+//! capture-oriented ioctl/memory surface only.
+//!
+#[doc(hidden)]
+pub mod bindings;
+pub mod ioctl;
+pub mod memory;
+
+// This can be needed to match nix errors that we expose.
+pub use nix;
+
+use std::convert::TryFrom;
+use std::fmt;
+use std::fmt::{Debug, Display};
+
+use enumn::N;
+use thiserror::Error;
+
+// The goal of this library is to provide two layers of abstraction:
+// ioctl: direct, safe counterparts of the V4L2 ioctls.
+// device/queue/buffer: higher abstraction, still mapping to core V4L2 mechanics.
+
+/// Possible directions for the queue
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub enum QueueDirection {
+    Output,
+    Capture,
+}
+
+/// Possible classes for this queue.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
+pub enum QueueClass {
+    Video,
+    Vbi,
+    SlicedVbi,
+    VideoOverlay,
+    VideoMplane,
+    Sdr,
+    Meta,
+}
+
+/// Types of queues currently supported by this library.
+#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, N)]
+#[repr(u32)]
+pub enum QueueType {
+    VideoCapture = bindings::v4l2_buf_type_V4L2_BUF_TYPE_VIDEO_CAPTURE,
+    VideoOutput = bindings::v4l2_buf_type_V4L2_BUF_TYPE_VIDEO_OUTPUT,
+    VideoOverlay = bindings::v4l2_buf_type_V4L2_BUF_TYPE_VIDEO_OVERLAY,
+    VbiCapture = bindings::v4l2_buf_type_V4L2_BUF_TYPE_VBI_CAPTURE,
+    VbiOutput = bindings::v4l2_buf_type_V4L2_BUF_TYPE_VBI_OUTPUT,
+    SlicedVbiCapture = bindings::v4l2_buf_type_V4L2_BUF_TYPE_SLICED_VBI_CAPTURE,
+    SlicedVbiOutput = bindings::v4l2_buf_type_V4L2_BUF_TYPE_SLICED_VBI_OUTPUT,
+    VideoOutputOverlay = bindings::v4l2_buf_type_V4L2_BUF_TYPE_VIDEO_OUTPUT_OVERLAY,
+    VideoCaptureMplane = bindings::v4l2_buf_type_V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE,
+    VideoOutputMplane = bindings::v4l2_buf_type_V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE,
+    SdrCapture = bindings::v4l2_buf_type_V4L2_BUF_TYPE_SDR_CAPTURE,
+    SdrOutput = bindings::v4l2_buf_type_V4L2_BUF_TYPE_SDR_OUTPUT,
+    MetaCapture = bindings::v4l2_buf_type_V4L2_BUF_TYPE_META_CAPTURE,
+    MetaOutput = bindings::v4l2_buf_type_V4L2_BUF_TYPE_META_OUTPUT,
+}
+
+impl QueueType {
+    /// Returns the queue corresponding to the passed `direction` and `class`.
+    pub fn from_dir_and_class(direction: QueueDirection, class: QueueClass) -> Self {
+        match (direction, class) {
+            (QueueDirection::Capture, QueueClass::Video) => Self::VideoCapture,
+            (QueueDirection::Output, QueueClass::Video) => Self::VideoOutput,
+            (QueueDirection::Capture, QueueClass::VideoOverlay) => Self::VideoOverlay,
+            (QueueDirection::Output, QueueClass::VideoOverlay) => Self::VideoOutputOverlay,
+            (QueueDirection::Capture, QueueClass::Vbi) => Self::VbiCapture,
+            (QueueDirection::Output, QueueClass::Vbi) => Self::VbiOutput,
+            (QueueDirection::Capture, QueueClass::SlicedVbi) => Self::SlicedVbiCapture,
+            (QueueDirection::Output, QueueClass::SlicedVbi) => Self::SlicedVbiOutput,
+            (QueueDirection::Capture, QueueClass::VideoMplane) => Self::VideoCaptureMplane,
+            (QueueDirection::Output, QueueClass::VideoMplane) => Self::VideoOutputMplane,
+            (QueueDirection::Capture, QueueClass::Sdr) => Self::SdrCapture,
+            (QueueDirection::Output, QueueClass::Sdr) => Self::SdrOutput,
+            (QueueDirection::Capture, QueueClass::Meta) => Self::MetaCapture,
+            (QueueDirection::Output, QueueClass::Meta) => Self::MetaOutput,
+        }
+    }
+
+    /// Returns whether the queue type is multiplanar.
+    pub fn is_multiplanar(&self) -> bool {
+        matches!(
+            self,
+            QueueType::VideoCaptureMplane | QueueType::VideoOutputMplane
+        )
+    }
+
+    /// Returns the direction of the queue type (Output or Capture).
+    pub fn direction(&self) -> QueueDirection {
+        match self {
+            QueueType::VideoOutput
+            | QueueType::VideoOutputMplane
+            | QueueType::VideoOverlay
+            | QueueType::VideoOutputOverlay
+            | QueueType::VbiOutput
+            | QueueType::SlicedVbiOutput
+            | QueueType::SdrOutput
+            | QueueType::MetaOutput => QueueDirection::Output,
+
+            QueueType::VideoCapture
+            | QueueType::VbiCapture
+            | QueueType::SlicedVbiCapture
+            | QueueType::VideoCaptureMplane
+            | QueueType::SdrCapture
+            | QueueType::MetaCapture => QueueDirection::Capture,
+        }
+    }
+
+    pub fn class(&self) -> QueueClass {
+        match self {
+            QueueType::VideoCapture | QueueType::VideoOutput => QueueClass::Video,
+            QueueType::VideoOverlay | QueueType::VideoOutputOverlay => QueueClass::VideoOverlay,
+            QueueType::VbiCapture | QueueType::VbiOutput => QueueClass::Vbi,
+            QueueType::SlicedVbiCapture | QueueType::SlicedVbiOutput => QueueClass::SlicedVbi,
+            QueueType::VideoCaptureMplane | QueueType::VideoOutputMplane => QueueClass::VideoMplane,
+            QueueType::SdrCapture | QueueType::SdrOutput => QueueClass::Sdr,
+            QueueType::MetaCapture | QueueType::MetaOutput => QueueClass::Meta,
+        }
+    }
+}
+
+impl Display for QueueType {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        Debug::fmt(self, f)
+    }
+}
+
+/// A Fourcc pixel format, used to pass formats to V4L2. It can be converted
+/// back and forth from a 32-bit integer, or a 4-bytes string.
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Default)]
+pub struct PixelFormat(u32);
+
+impl PixelFormat {
+    pub const fn from_u32(v: u32) -> Self {
+        Self(v)
+    }
+
+    pub const fn to_u32(self) -> u32 {
+        self.0
+    }
+
+    pub const fn from_fourcc(n: &[u8; 4]) -> Self {
+        Self(n[0] as u32 | (n[1] as u32) << 8 | (n[2] as u32) << 16 | (n[3] as u32) << 24)
+    }
+
+    pub const fn to_fourcc(self) -> [u8; 4] {
+        self.0.to_le_bytes()
+    }
+}
+
+/// Converts a Fourcc in 32-bit integer format (like the ones passed in V4L2
+/// structures) into the matching pixel format.
+///
+/// # Examples
+///
+/// ```
+/// # use v4l2r::PixelFormat;
+/// // Fourcc representation of NV12.
+/// let nv12 = u32::from_le(0x3231564e);
+/// let f = PixelFormat::from(nv12);
+/// assert_eq!(u32::from(f), nv12);
+/// ```
+impl From<u32> for PixelFormat {
+    fn from(i: u32) -> Self {
+        Self::from_u32(i)
+    }
+}
+
+/// Converts a pixel format back to its 32-bit representation.
+///
+/// # Examples
+///
+/// ```
+/// # use v4l2r::PixelFormat;
+/// // Fourcc representation of NV12.
+/// let nv12 = u32::from_le(0x3231564e);
+/// let f = PixelFormat::from(nv12);
+/// assert_eq!(u32::from(f), nv12);
+/// ```
+impl From<PixelFormat> for u32 {
+    fn from(format: PixelFormat) -> Self {
+        format.to_u32()
+    }
+}
+
+/// Simple way to convert a string litteral (e.g. b"NV12") into a pixel
+/// format that can be passed to V4L2.
+///
+/// # Examples
+///
+/// ```
+/// # use v4l2r::PixelFormat;
+/// let nv12 = b"NV12";
+/// let f = PixelFormat::from(nv12);
+/// assert_eq!(&<[u8; 4]>::from(f), nv12);
+/// ```
+impl From<&[u8; 4]> for PixelFormat {
+    fn from(n: &[u8; 4]) -> Self {
+        Self::from_fourcc(n)
+    }
+}
+
+/// Convert a pixel format back to its 4-character representation.
+///
+/// # Examples
+///
+/// ```
+/// # use v4l2r::PixelFormat;
+/// let nv12 = b"NV12";
+/// let f = PixelFormat::from(nv12);
+/// assert_eq!(&<[u8; 4]>::from(f), nv12);
+/// ```
+impl From<PixelFormat> for [u8; 4] {
+    fn from(format: PixelFormat) -> Self {
+        format.to_fourcc()
+    }
+}
+
+/// Produces a debug string for this PixelFormat, including its hexadecimal
+/// and string representation.
+///
+/// # Examples
+///
+/// ```
+/// # use v4l2r::PixelFormat;
+/// // Fourcc representation of NV12.
+/// let nv12 = u32::from_le(0x3231564e);
+/// let f = PixelFormat::from(nv12);
+/// assert_eq!(format!("{:?}", f), "0x3231564e (NV12)");
+/// ```
+impl fmt::Debug for PixelFormat {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_fmt(format_args!("0x{:08x} ({})", self.0, self))
+    }
+}
+
+/// Produces a displayable form of this PixelFormat.
+///
+/// # Examples
+///
+/// ```
+/// # use v4l2r::PixelFormat;
+/// // Fourcc representation of NV12.
+/// let nv12 = u32::from_le(0x3231564e);
+/// let f = PixelFormat::from(nv12);
+/// assert_eq!(f.to_string(), "NV12");
+/// ```
+impl fmt::Display for PixelFormat {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let fourcc = self
+            .0
+            .to_le_bytes()
+            .iter()
+            .map(|&x| x as char)
+            .collect::<String>();
+        f.write_str(fourcc.as_str())
+    }
+}
+
+/// Description of a single plane in a format.
+#[derive(Debug, PartialEq, Clone, Default)]
+pub struct PlaneLayout {
+    /// Useful size of the plane ; the backing memory must be at least that large.
+    pub sizeimage: u32,
+    /// Bytes per line of data. Only meaningful for image formats.
+    pub bytesperline: u32,
+}
+
+/// Unified representation of a V4L2 format capable of handling both single
+/// and multi-planar formats. When the single-planar API is used, only
+/// one plane shall be used - attempts to have more will be rejected by the
+/// ioctl wrappers.
+#[derive(Debug, PartialEq, Clone, Default)]
+pub struct Format {
+    /// Width of the image in pixels.
+    pub width: u32,
+    /// Height of the image in pixels.
+    pub height: u32,
+    /// Format each pixel is encoded in.
+    pub pixelformat: PixelFormat,
+    /// Individual layout of each plane in this format. The exact number of planes
+    /// is defined by `pixelformat`.
+    pub plane_fmt: Vec<PlaneLayout>,
+}
+
+#[derive(Debug, Error, PartialEq)]
+pub enum FormatConversionError {
+    #[error("too many planes ({0}) specified,")]
+    TooManyPlanes(usize),
+    #[error("invalid buffer type requested")]
+    InvalidBufferType(u32),
+}
+
+impl TryFrom<bindings::v4l2_format> for Format {
+    type Error = FormatConversionError;
+
+    fn try_from(fmt: bindings::v4l2_format) -> std::result::Result<Self, Self::Error> {
+        match fmt.type_ {
+            bindings::v4l2_buf_type_V4L2_BUF_TYPE_VIDEO_CAPTURE
+            | bindings::v4l2_buf_type_V4L2_BUF_TYPE_VIDEO_OUTPUT => {
+                let pix = unsafe { &fmt.fmt.pix };
+                Ok(Format {
+                    width: pix.width,
+                    height: pix.height,
+                    pixelformat: PixelFormat::from(pix.pixelformat),
+                    plane_fmt: vec![PlaneLayout {
+                        bytesperline: pix.bytesperline,
+                        sizeimage: pix.sizeimage,
+                    }],
+                })
+            }
+            bindings::v4l2_buf_type_V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
+            | bindings::v4l2_buf_type_V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE => {
+                let pix_mp = unsafe { &fmt.fmt.pix_mp };
+
+                // Can only happen if we passed a malformed v4l2_format.
+                if pix_mp.num_planes as usize > pix_mp.plane_fmt.len() {
+                    return Err(Self::Error::TooManyPlanes(pix_mp.num_planes as usize));
+                }
+
+                let mut plane_fmt = Vec::new();
+                for i in 0..pix_mp.num_planes as usize {
+                    let plane = &pix_mp.plane_fmt[i];
+                    plane_fmt.push(PlaneLayout {
+                        sizeimage: plane.sizeimage,
+                        bytesperline: plane.bytesperline,
+                    });
+                }
+
+                Ok(Format {
+                    width: pix_mp.width,
+                    height: pix_mp.height,
+                    pixelformat: PixelFormat::from(pix_mp.pixelformat),
+                    plane_fmt,
+                })
+            }
+            t => Err(Self::Error::InvalidBufferType(t)),
+        }
+    }
+}
+
+/// Quickly build a usable `Format` from a pixel format and resolution.
+///
+/// # Examples
+///
+/// ```
+/// # use v4l2r::Format;
+/// let f = Format::from((b"NV12", (640, 480)));
+/// assert_eq!(f.width, 640);
+/// assert_eq!(f.height, 480);
+/// assert_eq!(f.pixelformat.to_string(), "NV12");
+/// assert_eq!(f.plane_fmt.len(), 0);
+/// ```
+impl<T: Into<PixelFormat>> From<(T, (usize, usize))> for Format {
+    fn from((pixel_format, (width, height)): (T, (usize, usize))) -> Self {
+        Format {
+            width: width as u32,
+            height: height as u32,
+            pixelformat: pixel_format.into(),
+            ..Default::default()
+        }
+    }
+}
+
+/// A more elegant representation for `v4l2_rect`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct Rect {
+    pub left: i32,
+    pub top: i32,
+    pub width: u32,
+    pub height: u32,
+}
+
+impl Rect {
+    pub fn new(left: i32, top: i32, width: u32, height: u32) -> Rect {
+        Rect {
+            left,
+            top,
+            width,
+            height,
+        }
+    }
+}
+
+impl From<bindings::v4l2_rect> for Rect {
+    fn from(rect: bindings::v4l2_rect) -> Self {
+        Rect {
+            left: rect.left,
+            top: rect.top,
+            width: rect.width,
+            height: rect.height,
+        }
+    }
+}
+
+impl From<bindings::v4l2_selection> for Rect {
+    fn from(selection: bindings::v4l2_selection) -> Self {
+        Self::from(selection.r)
+    }
+}
+
+impl From<Rect> for bindings::v4l2_rect {
+    fn from(rect: Rect) -> Self {
+        bindings::v4l2_rect {
+            left: rect.left,
+            top: rect.top,
+            width: rect.width,
+            height: rect.height,
+        }
+    }
+}
+
+impl Display for Rect {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "({}, {}), {}x{}",
+            self.left, self.top, self.width, self.height
+        )
+    }
+}
+
+/// Equivalent of `enum v4l2_colorspace`.
+#[repr(u32)]
+#[derive(Debug, Default, Copy, Clone, PartialEq, Eq, N)]
+pub enum Colorspace {
+    #[default]
+    Default = bindings::v4l2_colorspace_V4L2_COLORSPACE_DEFAULT,
+    Smpte170M = bindings::v4l2_colorspace_V4L2_COLORSPACE_SMPTE170M,
+    Smpte240M = bindings::v4l2_colorspace_V4L2_COLORSPACE_SMPTE240M,
+    Rec709 = bindings::v4l2_colorspace_V4L2_COLORSPACE_REC709,
+    Bt878 = bindings::v4l2_colorspace_V4L2_COLORSPACE_BT878,
+    SystemM470 = bindings::v4l2_colorspace_V4L2_COLORSPACE_470_SYSTEM_M,
+    SystemBG470 = bindings::v4l2_colorspace_V4L2_COLORSPACE_470_SYSTEM_BG,
+    Jpeg = bindings::v4l2_colorspace_V4L2_COLORSPACE_JPEG,
+    Srgb = bindings::v4l2_colorspace_V4L2_COLORSPACE_SRGB,
+    OpRgb = bindings::v4l2_colorspace_V4L2_COLORSPACE_OPRGB,
+    Bt2020 = bindings::v4l2_colorspace_V4L2_COLORSPACE_BT2020,
+    Raw = bindings::v4l2_colorspace_V4L2_COLORSPACE_RAW,
+    DciP3 = bindings::v4l2_colorspace_V4L2_COLORSPACE_DCI_P3,
+}
+
+/// Equivalent of `enum v4l2_xfer_func`.
+#[repr(u32)]
+#[derive(Debug, Default, Copy, Clone, PartialEq, Eq, N)]
+pub enum XferFunc {
+    #[default]
+    Default = bindings::v4l2_xfer_func_V4L2_XFER_FUNC_DEFAULT,
+    F709 = bindings::v4l2_xfer_func_V4L2_XFER_FUNC_709,
+    Srgb = bindings::v4l2_xfer_func_V4L2_XFER_FUNC_SRGB,
+    OpRgb = bindings::v4l2_xfer_func_V4L2_XFER_FUNC_OPRGB,
+    Smpte240M = bindings::v4l2_xfer_func_V4L2_XFER_FUNC_SMPTE240M,
+    None = bindings::v4l2_xfer_func_V4L2_XFER_FUNC_NONE,
+    DciP3 = bindings::v4l2_xfer_func_V4L2_XFER_FUNC_DCI_P3,
+    Smpte2084 = bindings::v4l2_xfer_func_V4L2_XFER_FUNC_SMPTE2084,
+}
+
+/// Equivalent of `enum v4l2_ycbcr_encoding`.
+#[repr(u32)]
+#[derive(Debug, Default, Copy, Clone, PartialEq, Eq, N)]
+pub enum YCbCrEncoding {
+    #[default]
+    Default = bindings::v4l2_ycbcr_encoding_V4L2_YCBCR_ENC_DEFAULT,
+    E601 = bindings::v4l2_ycbcr_encoding_V4L2_YCBCR_ENC_601,
+    E709 = bindings::v4l2_ycbcr_encoding_V4L2_YCBCR_ENC_709,
+    Xv601 = bindings::v4l2_ycbcr_encoding_V4L2_YCBCR_ENC_XV601,
+    Xv709 = bindings::v4l2_ycbcr_encoding_V4L2_YCBCR_ENC_XV709,
+    Sycc = bindings::v4l2_ycbcr_encoding_V4L2_YCBCR_ENC_SYCC,
+    Bt2020 = bindings::v4l2_ycbcr_encoding_V4L2_YCBCR_ENC_BT2020,
+    Bt2020ConstLum = bindings::v4l2_ycbcr_encoding_V4L2_YCBCR_ENC_BT2020_CONST_LUM,
+    Smpte240M = bindings::v4l2_ycbcr_encoding_V4L2_YCBCR_ENC_SMPTE240M,
+}
+
+/// Equivalent of `enum v4l2_quantization`.
+#[repr(u32)]
+#[derive(Debug, Default, Copy, Clone, PartialEq, Eq, N)]
+pub enum Quantization {
+    #[default]
+    Default = bindings::v4l2_quantization_V4L2_QUANTIZATION_DEFAULT,
+    FullRange = bindings::v4l2_quantization_V4L2_QUANTIZATION_FULL_RANGE,
+    LimRange = bindings::v4l2_quantization_V4L2_QUANTIZATION_LIM_RANGE,
+}

libs/v4l2r/src/memory.rs

@@ -0,0 +1,279 @@
+//! Abstracts the different kinds of backing memory (`MMAP`, `USERPTR`,
+//! `DMABUF`) supported by V4L2.
+//!
+//! V4L2 allows to use either memory that is provided by the device itself
+//! (MMAP) or memory imported via user allocation (USERPTR) or the dma-buf
+//! subsystem (DMABUF). This results in 2 very different behaviors and 3 memory
+//! types that we need to model.
+//!
+//! The `Memory` trait represents these memory types and is thus implemented
+//! by exacly 3 types: `MMAP`, `UserPtr`, and `DMABuf`. These types do very
+//! little apart from providing a constant with the corresponding V4L2 memory
+//! type they model, and implement the `SelfBacked` (for MMAP) or `Imported`
+//! (for `UserPtr` and `DMABuf`) traits to indicate where their memory comes
+//! from.
+//!
+//! The `PlaneHandle` trait is used by types which can bind to one of these
+//! memory types, i.e. a type that can represent a single memory plane of a
+//! buffer. For `MMAP` memory this is a void type (since `MMAP` provides its
+//! own memory). `UserPtr`, a `Vec<u8>` can adequately be used as backing
+//! memory, and for `DMABuf` we will use a file descriptor. For handles that
+//! can be mapped into the user address-space (and indeed for `MMAP` this is
+//! the only way to access the memory), the `Mappable` trait can be implemented.
+//!
+//! The set of handles that make all the planes for a given buffer is
+//! represented by the `BufferHandles` trait. This trait is more abstract since
+//! we may want to decide at runtime the kind of memory we want to use ;
+//! therefore this trait does not have any particular kind of memory attached to
+//! it. `PrimitiveBufferHandles` is used to represent plane handles which memory
+//! type is known at compilation time, and thus includes a reference to a
+//! `PlaneHandle` type and by transition its `Memory` type.
+mod dmabuf;
+mod mmap;
+mod userptr;
+
+pub use dmabuf::*;
+pub use mmap::*;
+pub use userptr::*;
+
+use crate::{
+    bindings::{self, v4l2_buffer__bindgen_ty_1, v4l2_plane__bindgen_ty_1},
+    ioctl::{PlaneMapping, QueryBufPlane},
+};
+use enumn::N;
+use std::os::unix::io::AsFd;
+use std::{fmt::Debug, ops::Deref};
+
+/// All the supported V4L2 memory types.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, N)]
+#[repr(u32)]
+pub enum MemoryType {
+    Mmap = bindings::v4l2_memory_V4L2_MEMORY_MMAP,
+    UserPtr = bindings::v4l2_memory_V4L2_MEMORY_USERPTR,
+    Overlay = bindings::v4l2_memory_V4L2_MEMORY_OVERLAY,
+    DmaBuf = bindings::v4l2_memory_V4L2_MEMORY_DMABUF,
+}
+
+/// Trait describing a memory type that can be used to back V4L2 buffers.
+pub trait Memory: 'static {
+    /// The memory type represented.
+    const MEMORY_TYPE: MemoryType;
+    /// The final type of the memory backing information in `struct v4l2_buffer` or `struct
+    /// v4l2_plane`.
+    type RawBacking;
+
+    /// Returns a reference to the memory backing information for `m` that is relevant for this
+    /// memory type.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure that `m` indeed belongs to a buffer of this memory type.
+    unsafe fn get_plane_buffer_backing(m: &bindings::v4l2_plane__bindgen_ty_1)
+        -> &Self::RawBacking;
+
+    /// Returns a reference to the memory backing information for `m` that is relevant for this memory type.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure that `m` indeed belongs to a buffer of this memory type.
+    unsafe fn get_single_planar_buffer_backing(
+        m: &bindings::v4l2_buffer__bindgen_ty_1,
+    ) -> &Self::RawBacking;
+
+    /// Returns a mutable reference to the memory backing information for `m` that is relevant for
+    /// this memory type.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure that `m` indeed belongs to a buffer of this memory type.
+    unsafe fn get_plane_buffer_backing_mut(
+        m: &mut bindings::v4l2_plane__bindgen_ty_1,
+    ) -> &mut Self::RawBacking;
+
+    /// Returns a mutable reference to the memory backing information for `m` that is relevant for
+    /// this memory type.
+    ///
+    /// # Safety
+    ///
+    /// The caller must ensure that `m` indeed belongs to a buffer of this memory type.
+    unsafe fn get_single_planar_buffer_backing_mut(
+        m: &mut bindings::v4l2_buffer__bindgen_ty_1,
+    ) -> &mut Self::RawBacking;
+}
+
+/// Trait for memory types that provide their own memory, i.e. MMAP.
+pub trait SelfBacked: Memory + Default {}
+
+/// Trait for memory types to which external memory must be attached to, i.e. UserPtr and
+/// DMABuf.
+pub trait Imported: Memory {}
+
+/// Trait for a handle that represents actual data for a single place. A buffer
+/// will have as many of these as it has planes.
+pub trait PlaneHandle: Debug + Send + 'static {
+    /// The kind of memory the handle attaches to.
+    type Memory: Memory;
+
+    /// Fill a plane of a multi-planar V4L2 buffer with the handle's information.
+    fn fill_v4l2_plane(&self, plane: &mut bindings::v4l2_plane);
+}
+
+// Trait for plane handles that provide access to their content through a map()
+// method (typically, MMAP buffers).
+pub trait Mappable: PlaneHandle {
+    /// Return a `PlaneMapping` enabling access to the memory of this handle.
+    fn map<D: AsFd>(device: &D, plane_info: &QueryBufPlane) -> Option<PlaneMapping>;
+}
+
+/// Trait for structures providing all the handles of a single buffer.
+pub trait BufferHandles: Send + Debug + 'static {
+    /// Enumeration of all the `MemoryType` supported by this type. Typically
+    /// a subset of `MemoryType` or `MemoryType` itself.
+    type SupportedMemoryType: Into<MemoryType> + Send + Clone + Copy;
+
+    /// Number of planes.
+    fn len(&self) -> usize;
+    /// Fill a plane of a multi-planar V4L2 buffer with the `index` handle's information.
+    fn fill_v4l2_plane(&self, index: usize, plane: &mut bindings::v4l2_plane);
+
+    /// Returns true if there are no handles here (unlikely).
+    fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+}
+
+/// Implementation of `BufferHandles` for all indexables of `PlaneHandle` (e.g. [`std::vec::Vec`]).
+///
+/// This is The simplest way to use primitive handles.
+impl<P, Q> BufferHandles for Q
+where
+    P: PlaneHandle,
+    Q: Send + Debug + 'static + Deref<Target = [P]>,
+{
+    type SupportedMemoryType = MemoryType;
+
+    fn len(&self) -> usize {
+        self.deref().len()
+    }
+
+    fn fill_v4l2_plane(&self, index: usize, plane: &mut bindings::v4l2_plane) {
+        self.deref()[index].fill_v4l2_plane(plane);
+    }
+}
+
+/// Trait for plane handles for which the final memory type is known at compile
+/// time.
+pub trait PrimitiveBufferHandles: BufferHandles {
+    type HandleType: PlaneHandle;
+    const MEMORY_TYPE: Self::SupportedMemoryType;
+}
+
+/// Implementation of `PrimitiveBufferHandles` for all indexables of `PlaneHandle` (e.g.
+/// [`std::vec::Vec`]).
+impl<P, Q> PrimitiveBufferHandles for Q
+where
+    P: PlaneHandle,
+    Q: Send + Debug + 'static + Deref<Target = [P]>,
+{
+    type HandleType = P;
+    const MEMORY_TYPE: Self::SupportedMemoryType = P::Memory::MEMORY_TYPE;
+}
+
+/// Conversion from `v4l2_buffer`'s backing information to `v4l2_plane`'s.
+impl From<(&v4l2_buffer__bindgen_ty_1, MemoryType)> for v4l2_plane__bindgen_ty_1 {
+    fn from((m, memory): (&v4l2_buffer__bindgen_ty_1, MemoryType)) -> Self {
+        match memory {
+            MemoryType::Mmap => v4l2_plane__bindgen_ty_1 {
+                // Safe because the buffer type is determined to be MMAP.
+                mem_offset: unsafe { m.offset },
+            },
+            MemoryType::UserPtr => v4l2_plane__bindgen_ty_1 {
+                // Safe because the buffer type is determined to be USERPTR.
+                userptr: unsafe { m.userptr },
+            },
+            MemoryType::DmaBuf => v4l2_plane__bindgen_ty_1 {
+                // Safe because the buffer type is determined to be DMABUF.
+                fd: unsafe { m.fd },
+            },
+            MemoryType::Overlay => Default::default(),
+        }
+    }
+}
+
+/// Conversion from `v4l2_plane`'s backing information to `v4l2_buffer`'s.
+impl From<(&v4l2_plane__bindgen_ty_1, MemoryType)> for v4l2_buffer__bindgen_ty_1 {
+    fn from((m, memory): (&v4l2_plane__bindgen_ty_1, MemoryType)) -> Self {
+        match memory {
+            MemoryType::Mmap => v4l2_buffer__bindgen_ty_1 {
+                // Safe because the buffer type is determined to be MMAP.
+                offset: unsafe { m.mem_offset },
+            },
+            MemoryType::UserPtr => v4l2_buffer__bindgen_ty_1 {
+                // Safe because the buffer type is determined to be USERPTR.
+                userptr: unsafe { m.userptr },
+            },
+            MemoryType::DmaBuf => v4l2_buffer__bindgen_ty_1 {
+                // Safe because the buffer type is determined to be DMABUF.
+                fd: unsafe { m.fd },
+            },
+            MemoryType::Overlay => Default::default(),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::bindings::v4l2_buffer__bindgen_ty_1;
+    use crate::bindings::v4l2_plane__bindgen_ty_1;
+    use crate::memory::MemoryType;
+
+    #[test]
+    // Purpose of this test is dubious as the members are overlapping anyway.
+    fn plane_m_to_buffer_m() {
+        let plane_m = v4l2_plane__bindgen_ty_1 {
+            mem_offset: 0xfeedc0fe,
+        };
+        assert_eq!(
+            unsafe { v4l2_buffer__bindgen_ty_1::from((&plane_m, MemoryType::Mmap)).offset },
+            0xfeedc0fe
+        );
+
+        let plane_m = v4l2_plane__bindgen_ty_1 {
+            userptr: 0xfeedc0fe,
+        };
+        assert_eq!(
+            unsafe { v4l2_buffer__bindgen_ty_1::from((&plane_m, MemoryType::UserPtr)).userptr },
+            0xfeedc0fe
+        );
+
+        let plane_m = v4l2_plane__bindgen_ty_1 { fd: 0x76543210 };
+        assert_eq!(
+            unsafe { v4l2_buffer__bindgen_ty_1::from((&plane_m, MemoryType::DmaBuf)).fd },
+            0x76543210
+        );
+    }
+
+    #[test]
+    // Purpose of this test is dubious as the members are overlapping anyway.
+    fn buffer_m_to_plane_m() {
+        let buffer_m = v4l2_buffer__bindgen_ty_1 { offset: 0xfeedc0fe };
+        assert_eq!(
+            unsafe { v4l2_plane__bindgen_ty_1::from((&buffer_m, MemoryType::Mmap)).mem_offset },
+            0xfeedc0fe
+        );
+
+        let buffer_m = v4l2_buffer__bindgen_ty_1 {
+            userptr: 0xfeedc0fe,
+        };
+        assert_eq!(
+            unsafe { v4l2_plane__bindgen_ty_1::from((&buffer_m, MemoryType::UserPtr)).userptr },
+            0xfeedc0fe
+        );
+
+        let buffer_m = v4l2_buffer__bindgen_ty_1 { fd: 0x76543210 };
+        assert_eq!(
+            unsafe { v4l2_plane__bindgen_ty_1::from((&buffer_m, MemoryType::DmaBuf)).fd },
+            0x76543210
+        );
+    }
+}

libs/v4l2r/src/memory/dmabuf.rs

@@ -0,0 +1,91 @@
+//! Operations specific to DMABuf-type buffers.
+use log::warn;
+
+use super::*;
+use crate::{bindings, ioctl};
+use std::os::fd::RawFd;
+use std::os::unix::io::{AsFd, AsRawFd};
+
+pub struct DmaBuf;
+
+pub type DmaBufferHandles<T> = Vec<DmaBufHandle<T>>;
+
+impl Memory for DmaBuf {
+    const MEMORY_TYPE: MemoryType = MemoryType::DmaBuf;
+    type RawBacking = RawFd;
+
+    unsafe fn get_plane_buffer_backing(
+        m: &bindings::v4l2_plane__bindgen_ty_1,
+    ) -> &Self::RawBacking {
+        &m.fd
+    }
+
+    unsafe fn get_single_planar_buffer_backing(
+        m: &bindings::v4l2_buffer__bindgen_ty_1,
+    ) -> &Self::RawBacking {
+        &m.fd
+    }
+
+    unsafe fn get_plane_buffer_backing_mut(
+        m: &mut bindings::v4l2_plane__bindgen_ty_1,
+    ) -> &mut Self::RawBacking {
+        &mut m.fd
+    }
+
+    unsafe fn get_single_planar_buffer_backing_mut(
+        m: &mut bindings::v4l2_buffer__bindgen_ty_1,
+    ) -> &mut Self::RawBacking {
+        &mut m.fd
+    }
+}
+
+impl Imported for DmaBuf {}
+
+pub trait DmaBufSource: AsRawFd + AsFd + Debug + Send {
+    fn len(&self) -> u64;
+
+    /// Make Clippy happy.
+    fn is_empty(&self) -> bool {
+        self.len() == 0
+    }
+}
+
+impl DmaBufSource for std::fs::File {
+    fn len(&self) -> u64 {
+        match self.metadata() {
+            Err(_) => {
+                warn!("Failed to compute File size for use as DMABuf, using 0...");
+                0
+            }
+            Ok(m) => m.len(),
+        }
+    }
+}
+
+/// Handle for a DMABUF plane. Any type that can provide a file descriptor is
+/// valid.
+#[derive(Debug)]
+pub struct DmaBufHandle<T: DmaBufSource>(pub T);
+
+impl<T: DmaBufSource> From<T> for DmaBufHandle<T> {
+    fn from(dmabuf: T) -> Self {
+        DmaBufHandle(dmabuf)
+    }
+}
+
+impl<T: DmaBufSource + 'static> PlaneHandle for DmaBufHandle<T> {
+    type Memory = DmaBuf;
+
+    fn fill_v4l2_plane(&self, plane: &mut bindings::v4l2_plane) {
+        plane.m.fd = self.0.as_raw_fd();
+        plane.length = self.0.len() as u32;
+    }
+}
+
+impl<T: DmaBufSource> DmaBufHandle<T> {
+    pub fn map(&self) -> Result<PlaneMapping, ioctl::MmapError> {
+        let len = self.0.len();
+
+        ioctl::mmap(&self.0, 0, len as u32)
+    }
+}

libs/v4l2r/src/memory/mmap.rs

@@ -0,0 +1,58 @@
+//! Operations specific to MMAP-type buffers.
+use super::*;
+use crate::{bindings, ioctl};
+use std::fmt::Debug;
+use std::os::fd::AsFd;
+
+#[derive(Default)]
+pub struct Mmap;
+
+impl Memory for Mmap {
+    const MEMORY_TYPE: MemoryType = MemoryType::Mmap;
+    type RawBacking = u32;
+
+    unsafe fn get_plane_buffer_backing(
+        m: &bindings::v4l2_plane__bindgen_ty_1,
+    ) -> &Self::RawBacking {
+        &m.mem_offset
+    }
+
+    unsafe fn get_single_planar_buffer_backing(
+        m: &bindings::v4l2_buffer__bindgen_ty_1,
+    ) -> &Self::RawBacking {
+        &m.offset
+    }
+
+    unsafe fn get_plane_buffer_backing_mut(
+        m: &mut bindings::v4l2_plane__bindgen_ty_1,
+    ) -> &mut Self::RawBacking {
+        &mut m.mem_offset
+    }
+
+    unsafe fn get_single_planar_buffer_backing_mut(
+        m: &mut bindings::v4l2_buffer__bindgen_ty_1,
+    ) -> &mut Self::RawBacking {
+        &mut m.offset
+    }
+}
+
+impl SelfBacked for Mmap {}
+
+/// Dummy handle for a MMAP plane, to use with APIs that require handles. MMAP
+/// buffers are backed by the device, and thus we don't need to attach any extra
+/// information to them.
+#[derive(Default, Debug, Clone)]
+pub struct MmapHandle;
+
+// There is no information to fill with MMAP buffers ; the index is enough.
+impl PlaneHandle for MmapHandle {
+    type Memory = Mmap;
+
+    fn fill_v4l2_plane(&self, _plane: &mut bindings::v4l2_plane) {}
+}
+
+impl Mappable for MmapHandle {
+    fn map<D: AsFd>(device: &D, plane_info: &QueryBufPlane) -> Option<PlaneMapping> {
+        ioctl::mmap(device, plane_info.mem_offset, plane_info.length).ok()
+    }
+}

libs/v4l2r/src/memory/userptr.rs

@@ -0,0 +1,77 @@
+//! Operations specific to UserPtr-type buffers.
+
+use super::*;
+use crate::bindings;
+
+pub struct UserPtr;
+
+impl Memory for UserPtr {
+    const MEMORY_TYPE: MemoryType = MemoryType::UserPtr;
+    type RawBacking = core::ffi::c_ulong;
+
+    unsafe fn get_plane_buffer_backing(
+        m: &bindings::v4l2_plane__bindgen_ty_1,
+    ) -> &Self::RawBacking {
+        &m.userptr
+    }
+
+    unsafe fn get_single_planar_buffer_backing(
+        m: &bindings::v4l2_buffer__bindgen_ty_1,
+    ) -> &Self::RawBacking {
+        &m.userptr
+    }
+
+    unsafe fn get_plane_buffer_backing_mut(
+        m: &mut bindings::v4l2_plane__bindgen_ty_1,
+    ) -> &mut Self::RawBacking {
+        &mut m.userptr
+    }
+
+    unsafe fn get_single_planar_buffer_backing_mut(
+        m: &mut bindings::v4l2_buffer__bindgen_ty_1,
+    ) -> &mut Self::RawBacking {
+        &mut m.userptr
+    }
+}
+
+impl Imported for UserPtr {}
+
+/// Handle for a USERPTR plane. These buffers are backed by userspace-allocated
+/// memory, which translates well into Rust's slice of `u8`s. Since slices also
+/// carry size information, we know that we are not passing unallocated areas
+/// of the address-space to the kernel.
+///
+/// USERPTR buffers have the particularity that the `length` field of `struct
+/// v4l2_buffer` must be set before doing a `QBUF` ioctl. This handle struct
+/// also takes care of that.
+#[derive(Debug)]
+pub struct UserPtrHandle<T: AsRef<[u8]> + Debug + Send + 'static>(pub T);
+
+impl<T: AsRef<[u8]> + Debug + Send + Clone> Clone for UserPtrHandle<T> {
+    fn clone(&self) -> Self {
+        UserPtrHandle(self.0.clone())
+    }
+}
+
+impl<T: AsRef<[u8]> + Debug + Send + 'static> AsRef<[u8]> for UserPtrHandle<T> {
+    fn as_ref(&self) -> &[u8] {
+        self.0.as_ref()
+    }
+}
+
+impl<T: AsRef<[u8]> + Debug + Send> From<T> for UserPtrHandle<T> {
+    fn from(buffer: T) -> Self {
+        UserPtrHandle(buffer)
+    }
+}
+
+impl<T: AsRef<[u8]> + Debug + Send + 'static> PlaneHandle for UserPtrHandle<T> {
+    type Memory = UserPtr;
+
+    fn fill_v4l2_plane(&self, plane: &mut bindings::v4l2_plane) {
+        let slice = AsRef::<[u8]>::as_ref(&self.0);
+
+        plane.m.userptr = slice.as_ptr() as std::os::raw::c_ulong;
+        plane.length = slice.len() as u32;
+    }
+}