backends: add headless backend
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Julian Orth
parent
37a0bd451b
commit
8b22255f6e
4 changed files with 317 additions and 1 deletions
305
src/backends/headless.rs
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305
src/backends/headless.rs
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@ -0,0 +1,305 @@
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use {
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crate::{
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async_engine::SpawnedFuture,
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backend::{Backend, BackendDrmDevice, BackendEvent, DrmDeviceId, DrmEvent},
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backends::headless::HeadlessBackendError::{
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CreateDrm, GetDrmNodes, MonitorFdFailed, MonitorFdReadable, NoDrmNodes, OpenDrmNode,
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},
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gfx_api::{GfxApi, GfxContext},
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io_uring::IoUringError,
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state::State,
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udev::{Udev, UdevDevice, UdevError, UdevMonitor},
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utils::{
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bitflags::BitflagsExt, clonecell::CloneCell, copyhashmap::CopyHashMap,
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errorfmt::ErrorFmt, hash_map_ext::HashMapExt, on_change::OnChange, oserror::OsError,
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},
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video::drm::{Drm, DrmError, DrmVersion, NodeType, get_drm_nodes_from_dev},
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},
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HeadlessBackendError::{
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AddUdevSubsystemMatch, CreateUdev, CreateUdevEnumerator, CreateUdevMonitor,
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DupUdevMonitorFd, EnableUdevReceiving, GetUdevEntry, ScanUdevDevices,
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},
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std::{cell::Cell, error::Error, rc::Rc},
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thiserror::Error,
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uapi::{
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AsUstr, OwnedFd,
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c::{self, dev_t},
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major, minor,
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},
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};
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#[derive(Debug, Error)]
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pub enum HeadlessBackendError {
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#[error("Could not create a udev instance")]
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CreateUdev(#[source] UdevError),
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#[error("Could not create a udev monitor")]
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CreateUdevMonitor(#[source] UdevError),
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#[error("Could not add a udev subsystem match")]
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AddUdevSubsystemMatch(#[source] UdevError),
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#[error("Could not enable udev receiving")]
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EnableUdevReceiving(#[source] UdevError),
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#[error("Could not dup udev monitor fd")]
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DupUdevMonitorFd(#[source] OsError),
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#[error("Could not create a udev enumerator")]
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CreateUdevEnumerator(#[source] UdevError),
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#[error("Could not scan udev device")]
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ScanUdevDevices(#[source] UdevError),
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#[error("Could not get udev entry")]
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GetUdevEntry(#[source] UdevError),
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#[error("Could not determine DRM nodes of device")]
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GetDrmNodes(#[source] OsError),
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#[error("Device has no DRM nodes")]
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NoDrmNodes,
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#[error("Could not open DRM node")]
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OpenDrmNode(#[source] OsError),
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#[error("Could not create Drm object")]
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CreateDrm(#[source] DrmError),
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#[error("Could not wait for monitor FD to become readable")]
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MonitorFdReadable(#[source] IoUringError),
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#[error("The monitor FD failed")]
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MonitorFdFailed,
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}
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pub struct HeadlessBackend {
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state: Rc<State>,
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udev: Rc<Udev>,
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monitor: Rc<UdevMonitor>,
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monitor_fd: Rc<OwnedFd>,
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devs: CopyHashMap<dev_t, Rc<HeadlessDrmDevice>>,
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render_device: Cell<Option<DrmDeviceId>>,
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}
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struct HeadlessDrmDevice {
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backend: Rc<HeadlessBackend>,
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id: DrmDeviceId,
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dev: dev_t,
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api: Cell<GfxApi>,
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drm: Drm,
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ctx: CloneCell<Option<Rc<dyn GfxContext>>>,
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events: OnChange<DrmEvent>,
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}
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const DRM: &[u8] = b"drm";
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pub async fn create(state: &Rc<State>) -> Result<Rc<HeadlessBackend>, HeadlessBackendError> {
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let udev = Rc::new(Udev::new().map_err(CreateUdev)?);
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let monitor = Rc::new(udev.create_monitor().map_err(CreateUdevMonitor)?);
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monitor
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.add_match_subsystem_devtype(Some(DRM), None)
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.map_err(AddUdevSubsystemMatch)?;
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monitor.enable_receiving().map_err(EnableUdevReceiving)?;
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let monitor_fd = uapi::fcntl_dupfd_cloexec(monitor.fd(), 0)
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.map(Rc::new)
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.map_err(Into::into)
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.map_err(DupUdevMonitorFd)?;
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Ok(Rc::new(HeadlessBackend {
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state: state.clone(),
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udev,
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monitor,
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monitor_fd,
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devs: Default::default(),
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render_device: Default::default(),
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}))
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}
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impl Backend for HeadlessBackend {
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fn run(self: Rc<Self>) -> SpawnedFuture<Result<(), Box<dyn Error>>> {
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let slf = self.clone();
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self.state.eng.spawn("headless backend", async move {
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slf.run().await?;
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Ok(())
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})
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}
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fn clear(&self) {
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for dev in self.devs.lock().drain_values() {
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dev.ctx.take();
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dev.events.clear();
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}
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}
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}
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fn is_primary_node(n: &[u8]) -> bool {
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match n.strip_prefix(b"card") {
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Some(r) => r.iter().copied().all(|c| matches!(c, b'0'..=b'9')),
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_ => false,
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}
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}
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impl HeadlessBackend {
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async fn run(self: Rc<Self>) -> Result<(), HeadlessBackendError> {
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if let Some(acceptor) = self.state.acceptor.get() {
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println!("WAYLAND_DISPLAY={}", acceptor.socket_name());
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}
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let mut enumerate = self.udev.create_enumerate().map_err(CreateUdevEnumerator)?;
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enumerate
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.add_match_subsystem(DRM)
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.map_err(AddUdevSubsystemMatch)?;
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enumerate.scan_devices().map_err(ScanUdevDevices)?;
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let mut entry_opt = enumerate.get_list_entry().map_err(GetUdevEntry)?;
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while let Some(entry) = entry_opt.take() {
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if let Ok(dev) = self.udev.create_device_from_syspath(entry.name()) {
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self.handle_device_add(dev);
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}
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entry_opt = entry.next();
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}
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self.state
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.backend_events
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.push(BackendEvent::DevicesEnumerated);
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loop {
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let res = self
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.state
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.ring
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.readable(&self.monitor_fd)
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.await
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.map_err(MonitorFdReadable)?;
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if res.intersects(c::POLLERR | c::POLLHUP) {
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return Err(MonitorFdFailed);
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}
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while let Some(dev) = self.monitor.receive_device() {
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if let Some(action) = dev.action()
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&& action.as_ustr() == "add"
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{
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self.handle_device_add(dev);
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}
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}
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}
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}
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fn handle_device_add(self: &Rc<Self>, dev: UdevDevice) {
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let num = dev.devnum();
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if let Err(e) = self.handle_device_add_(dev) {
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log::error!(
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"Could not add device {}:{}: {}",
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major(num),
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minor(num),
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ErrorFmt(e),
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);
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}
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}
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fn handle_device_add_(self: &Rc<Self>, dev: UdevDevice) -> Result<(), HeadlessBackendError> {
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let Some(subsystem) = dev.subsystem() else {
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return Ok(());
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};
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if subsystem.as_ustr() != DRM {
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return Ok(());
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}
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let Some(sysname) = dev.sysname() else {
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return Ok(());
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};
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if !is_primary_node(sysname.to_bytes()) {
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return Ok(());
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}
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let devnum = dev.devnum();
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if self.devs.contains(&devnum) {
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return Ok(());
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}
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let nodes = get_drm_nodes_from_dev(major(devnum), minor(devnum)).map_err(GetDrmNodes)?;
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let node = nodes
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.get(&NodeType::Render)
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.or_else(|| nodes.get(&NodeType::Primary))
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.ok_or(NoDrmNodes)?;
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let fd = uapi::open(&**node, c::O_RDWR | c::O_CLOEXEC, 0)
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.map_err(Into::into)
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.map_err(OpenDrmNode)?;
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let drm = Drm::open_existing(Rc::new(fd)).map_err(CreateDrm)?;
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let dev = Rc::new(HeadlessDrmDevice {
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backend: self.clone(),
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id: self.state.drm_dev_ids.next(),
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dev: devnum,
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api: Cell::new(self.state.default_gfx_api.get()),
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drm,
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ctx: Default::default(),
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events: Default::default(),
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});
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self.devs.set(devnum, dev.clone());
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self.state
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.backend_events
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.push(BackendEvent::NewDrmDevice(dev));
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Ok(())
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}
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}
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impl HeadlessDrmDevice {
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fn create_ctx(&self, api: GfxApi) -> Option<Rc<dyn GfxContext>> {
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match self.backend.state.create_gfx_context(&self.drm, Some(api)) {
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Ok(c) => Some(c),
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Err(e) => {
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log::error!("Could not create GFX context: {}", ErrorFmt(e));
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None
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}
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}
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}
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}
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impl BackendDrmDevice for HeadlessDrmDevice {
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fn id(&self) -> DrmDeviceId {
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self.id
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}
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fn event(&self) -> Option<DrmEvent> {
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self.events.events.pop()
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}
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fn on_change(&self, cb: Rc<dyn Fn()>) {
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self.events.on_change.set(Some(cb));
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}
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fn dev_t(&self) -> dev_t {
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self.dev
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}
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fn make_render_device(&self) {
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if self.is_render_device() {
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return;
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}
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let ctx = match self.ctx.get() {
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Some(ctx) => ctx,
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_ => {
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let Some(ctx) = self.create_ctx(self.gtx_api()) else {
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return;
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};
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self.ctx.set(Some(ctx.clone()));
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ctx
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}
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};
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self.backend.render_device.set(Some(self.id));
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self.backend.state.set_render_ctx(Some(ctx));
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}
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fn set_gfx_api(&self, api: GfxApi) {
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if self.api.get() == api {
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return;
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}
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if self.ctx.is_none() {
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self.api.set(api);
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return;
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}
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let Some(ctx) = self.create_ctx(api) else {
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return;
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};
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self.ctx.set(Some(ctx.clone()));
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self.api.set(api);
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self.events.send_event(DrmEvent::GfxApiChanged);
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if self.is_render_device() {
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self.backend.state.set_render_ctx(Some(ctx));
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}
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}
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fn gtx_api(&self) -> GfxApi {
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self.api.get()
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}
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fn version(&self) -> Result<DrmVersion, DrmError> {
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self.drm.version()
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}
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fn set_direct_scanout_enabled(&self, enabled: bool) {
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let _ = enabled;
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}
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fn is_render_device(&self) -> bool {
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self.backend.render_device.get() == Some(self.id)
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}
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}
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