Files
feresaria/portal/src/capture.rs
T
Samuel Onoja baca852ee9 Support isolated live window ScreenCast streams
Render selected toplevels through a private portal-only capture protocol, preserve logical snapshot geometry, and renegotiate PipeWire video on window resizing. Bound outstanding snapshots and retry temporary contention; stop on source closure and session locking.

Validation: portal unit tests (31), capture budget unit, private-bus portal contracts, and real nested/PipeWire isolation, workspace, resize, close and paused-lock tests pass. Independent review cleared. Monitor restore integration timed out on both this build and the unchanged previous compositor under the current nested host.
2026-09-30 04:02:33 +01:00

642 lines
21 KiB
Rust

//! Bounded, cancellable Wayland capture. No screenshots or external capture tools.
use ferese_protocols::window_capture::v1::client::ferese_window_capture_manager_v1 as window_manager;
use memmap2::MmapMut;
use serde::{Deserialize, Serialize};
use std::{
fs::File,
os::fd::{AsFd, AsRawFd, FromRawFd},
sync::{
Arc,
atomic::{AtomicBool, Ordering},
},
time::{Duration, Instant},
};
use wayland_client::{
Connection, Dispatch, EventQueue, QueueHandle, WEnum,
protocol::{wl_buffer, wl_output, wl_registry, wl_shm, wl_shm_pool},
};
use wayland_protocols_wlr::screencopy::v1::client::{
zwlr_screencopy_frame_v1 as frame, zwlr_screencopy_manager_v1 as manager,
};
pub const BUSY: &str = "Window capture snapshot pool is busy";
#[derive(Clone, Debug, Serialize, Deserialize)]
pub struct Source {
pub name: String,
pub label: String,
pub width: i32,
pub height: i32,
pub x: i32,
pub y: i32,
pub scale: i32,
}
impl Source {
pub fn window_id(&self) -> Option<u64> {
self.name.strip_prefix("window:")?.parse().ok()
}
}
struct Output {
global: u32,
proxy: wl_output::WlOutput,
source: Source,
transform: wl_output::Transform,
}
pub struct Frame {
pub logical_size: Option<(u32, u32)>,
pub width: u32,
pub height: u32,
pub stride: u32,
pub pixels: Vec<u8>,
}
struct Buffer {
_file: File,
map: MmapMut,
proxy: wl_buffer::WlBuffer,
width: u32,
height: u32,
stride: u32,
format: wl_shm::Format,
}
impl Drop for Buffer {
fn drop(&mut self) {
self.proxy.destroy();
}
}
#[derive(Default)]
struct State {
outputs: Vec<Output>,
manager: Option<manager::ZwlrScreencopyManagerV1>,
window_manager: Option<window_manager::FereseWindowCaptureManagerV1>,
shm: Option<wl_shm::WlShm>,
buffer: Option<Buffer>,
result: Option<Result<(), String>>,
flipped: bool,
logical_size: Option<(u32, u32)>,
busy: bool,
}
pub struct Capture {
connection: Connection,
queue: EventQueue<State>,
state: State,
selected_output: Option<u32>,
}
impl Capture {
pub fn connect(stop: &AtomicBool) -> Result<Self, String> {
let connection = Connection::connect_to_env().map_err(|e| e.to_string())?;
let queue = connection.new_event_queue();
connection.display().get_registry(&queue.handle(), ());
let mut this = Self {
connection,
queue,
state: State::default(),
selected_output: None,
};
// Two syncs deliver registry bindings and output metadata without an
// uninterruptible roundtrip on a stalled compositor.
this.sync(stop)?;
this.sync(stop)?;
if (this.state.manager.is_none() && this.state.window_manager.is_none())
|| this.state.shm.is_none()
{
return Err("Ferese screen capture is unavailable in this session".into());
}
Ok(this)
}
fn sync(&mut self, stop: &AtomicBool) -> Result<(), String> {
let done = Arc::new(AtomicBool::new(false));
self.connection
.display()
.sync(&self.queue.handle(), done.clone());
let deadline = Instant::now() + Duration::from_secs(5);
while !done.load(Ordering::Relaxed) {
self.dispatch(stop, deadline)?;
}
Ok(())
}
pub fn supports_windows(&self) -> bool {
self.state.window_manager.is_some()
}
pub fn generation(&self, name: &str) -> Option<u32> {
self.state
.outputs
.iter()
.find(|output| output.source.name == name)
.map(|output| output.global)
}
pub fn pin_output(&mut self, name: &str, generation: u32) -> Result<(), String> {
if self.generation(name) != Some(generation) {
return Err("Shared monitor was replaced".into());
}
self.selected_output = Some(generation);
Ok(())
}
pub fn validate_sources(&mut self, selected: &[(String, u32)]) -> Result<(), String> {
self.sync(&AtomicBool::new(false))?;
for (name, generation) in selected {
if self.generation(name) != Some(*generation) {
return Err("A selected display disconnected during approval".into());
}
}
Ok(())
}
pub fn sources(&self) -> Vec<Source> {
self.state
.outputs
.iter()
.map(|o| {
let mut source = o.source.clone();
if swaps_axes(o.transform) {
std::mem::swap(&mut source.width, &mut source.height);
}
source
})
.collect()
}
pub fn frame(
&mut self,
name: &str,
cursor: bool,
stop: &AtomicBool,
mut pixels: Vec<u8>,
) -> Result<Frame, String> {
self.state.result = None;
self.state.flipped = false;
self.state.logical_size = None;
self.state.busy = false;
let (frame, transform) = if let Some(id) = name
.strip_prefix("window:")
.and_then(|id| id.parse::<u64>().ok())
{
let manager = self
.state
.window_manager
.as_ref()
.ok_or("Window capture is unavailable")?;
(
manager.capture_window(
(id >> 32) as u32,
id as u32,
cursor as u32,
&self.queue.handle(),
(),
),
wl_output::Transform::Normal,
)
} else {
let output = self
.state
.outputs
.iter()
.find(|o| o.source.name == name)
.ok_or("Shared monitor disconnected")?;
if self
.selected_output
.is_some_and(|selected| selected != output.global)
{
return Err("Shared monitor was replaced".into());
}
self.selected_output = Some(output.global);
let manager = self
.state
.manager
.as_ref()
.ok_or("Monitor capture is unavailable")?;
(
manager.capture_output(cursor as i32, &output.proxy, &self.queue.handle(), ()),
output.transform,
)
};
let deadline = Instant::now() + Duration::from_secs(5);
while self.state.result.is_none() {
if let Err(error) = self.dispatch(stop, deadline) {
frame.destroy();
return Err(error);
}
}
frame.destroy();
self.state.result.take().unwrap()?;
let buffer = self
.state
.buffer
.as_ref()
.ok_or("Capture supplied no buffer")?;
let (width, height) = copy_oriented_pixels(
&buffer.map,
buffer.width,
buffer.height,
buffer.stride,
transform,
self.state.flipped,
&mut pixels,
);
Ok(Frame {
logical_size: self.state.logical_size,
width,
height,
stride: width * 4,
pixels,
})
}
fn dispatch(&mut self, stop: &AtomicBool, deadline: Instant) -> Result<(), String> {
if stop.load(Ordering::Relaxed) {
return Err("Capture cancelled".into());
}
if Instant::now() >= deadline {
return Err("Compositor capture timed out".into());
}
self.queue
.dispatch_pending(&mut self.state)
.map_err(|e| e.to_string())?;
self.connection.flush().map_err(|e| e.to_string())?;
if let Some(read) = self.queue.prepare_read() {
let mut fd = libc::pollfd {
fd: read.connection_fd().as_raw_fd(),
events: libc::POLLIN,
revents: 0,
};
// SAFETY: a single valid pollfd, bounded timeout; Wayland owns the FD.
let ready = unsafe { libc::poll(&mut fd, 1, 20) };
if ready > 0 {
read.read().map_err(|e| e.to_string())?;
} else if ready < 0
&& std::io::Error::last_os_error().kind() != std::io::ErrorKind::Interrupted
{
return Err(std::io::Error::last_os_error().to_string());
}
}
self.queue
.dispatch_pending(&mut self.state)
.map_err(|e| e.to_string())?;
Ok(())
}
}
impl Dispatch<wl_registry::WlRegistry, ()> for State {
fn event(
state: &mut Self,
registry: &wl_registry::WlRegistry,
event: wl_registry::Event,
_: &(),
_: &Connection,
qh: &QueueHandle<Self>,
) {
match event {
wl_registry::Event::Global {
name,
interface,
version,
} => match interface.as_str() {
"wl_output" => state.outputs.push(Output {
global: name,
transform: wl_output::Transform::Normal,
proxy: registry.bind(name, version.min(4), qh, name),
source: Source {
name: format!("output-{name}"),
label: "Display".into(),
width: 0,
height: 0,
x: 0,
y: 0,
scale: 1,
},
}),
"ferese_window_capture_manager_v1" => {
state.window_manager = Some(registry.bind(name, 1, qh, ()))
}
"wl_shm" => state.shm = Some(registry.bind(name, 1, qh, ())),
"zwlr_screencopy_manager_v1" => {
state.manager = Some(registry.bind(name, version.min(3), qh, ()))
}
_ => (),
},
wl_registry::Event::GlobalRemove { name } => state.outputs.retain(|o| o.global != name),
_ => (),
}
}
}
impl Dispatch<wl_output::WlOutput, u32> for State {
fn event(
state: &mut Self,
_: &wl_output::WlOutput,
event: wl_output::Event,
name: &u32,
_: &Connection,
_: &QueueHandle<Self>,
) {
let Some(output) = state.outputs.iter_mut().find(|o| o.global == *name) else {
return;
};
match event {
wl_output::Event::Name { name } => output.source.name = name,
wl_output::Event::Description { description } => output.source.label = description,
wl_output::Event::Geometry {
x, y, transform, ..
} => {
if let WEnum::Value(transform) = transform {
output.transform = transform;
}
output.source.x = x;
output.source.y = y;
}
wl_output::Event::Scale { factor } => output.source.scale = factor.max(1),
wl_output::Event::Mode {
flags: WEnum::Value(flags),
width,
height,
..
} if flags.contains(wl_output::Mode::Current) => {
output.source.width = width;
output.source.height = height;
}
_ => (),
}
}
}
impl Dispatch<frame::ZwlrScreencopyFrameV1, ()> for State {
fn event(
state: &mut Self,
frame: &frame::ZwlrScreencopyFrameV1,
event: frame::Event,
_: &(),
_: &Connection,
qh: &QueueHandle<Self>,
) {
match event {
frame::Event::Buffer {
format: WEnum::Value(format),
width,
height,
stride,
} => {
let result = (|| {
if format != wl_shm::Format::Argb8888 && format != wl_shm::Format::Xrgb8888 {
return Err("Unsupported capture pixel format".into());
}
let bytes = buffer_size(width, height, stride)?;
if let Some(buffer) = &state.buffer
&& (buffer.width, buffer.height, buffer.stride, buffer.format)
== (width, height, stride, format)
{
frame.copy(&buffer.proxy);
return Ok(());
}
// SAFETY: fixed NUL-terminated name and a newly owned memfd.
let fd = unsafe {
libc::memfd_create(c"ferese-screencast".as_ptr(), libc::MFD_CLOEXEC)
};
if fd < 0 {
return Err(std::io::Error::last_os_error().to_string());
}
let file = unsafe { File::from_raw_fd(fd) };
file.set_len(bytes as u64).map_err(|e| e.to_string())?;
// SAFETY: the file has the checked mapping length and lives with the mapping.
let map = unsafe { MmapMut::map_mut(&file) }.map_err(|e| e.to_string())?;
let pool = state
.shm
.as_ref()
.ok_or("Missing shared memory global")?
.create_pool(file.as_fd(), bytes as i32, qh, ());
let proxy = pool.create_buffer(
0,
width as i32,
height as i32,
stride as i32,
format,
qh,
(),
);
pool.destroy();
frame.copy(&proxy);
state.buffer = Some(Buffer {
_file: file,
map,
proxy,
width,
height,
stride,
format,
});
Ok::<(), String>(())
})();
if let Err(e) = result {
state.result = Some(Err(e));
}
}
frame::Event::Ready { .. } => state.result = Some(Ok(())),
frame::Event::Failed => {
state.result = Some(Err(if state.busy {
BUSY.into()
} else {
"Capture ended: session locked, source closed, or compositor unavailable".into()
}))
}
frame::Event::Flags {
flags: WEnum::Value(flags),
} => state.flipped = flags.contains(frame::Flags::YInvert),
_ => (),
}
}
}
fn swaps_axes(transform: wl_output::Transform) -> bool {
matches!(
transform,
wl_output::Transform::_90
| wl_output::Transform::_270
| wl_output::Transform::Flipped90
| wl_output::Transform::Flipped270
)
}
// Screencopy supplies output-buffer coordinates. Normalize both the output's
// presentation transform and the independent YInvert storage flag before
// publishing upright, tightly packed BGRx frames to PipeWire.
fn copy_oriented_pixels(
source: &[u8],
width: u32,
height: u32,
stride: u32,
transform: wl_output::Transform,
y_invert: bool,
pixels: &mut Vec<u8>,
) -> (u32, u32) {
use wl_output::Transform;
let (out_width, out_height) = if swaps_axes(transform) {
(height, width)
} else {
(width, height)
};
let row = out_width as usize * 4;
pixels.resize(row * out_height as usize, 0);
// The usual DRM and nested outputs need only one contiguous copy per row.
if matches!(transform, Transform::Normal | Transform::Flipped180) {
let flip = y_invert ^ (transform == Transform::Flipped180);
for (y, dst) in pixels.chunks_exact_mut(row).enumerate() {
let sy = if flip { height as usize - 1 - y } else { y };
let start = sy * stride as usize;
dst.copy_from_slice(&source[start..start + row]);
}
return (out_width, out_height);
}
for y in 0..out_height {
for x in 0..out_width {
let (sx, mut sy) = match transform {
Transform::_90 => (y, height - 1 - x),
Transform::_180 => (width - 1 - x, height - 1 - y),
Transform::_270 => (width - 1 - y, x),
Transform::Flipped => (width - 1 - x, y),
Transform::Flipped90 => (y, x),
Transform::Flipped270 => (width - 1 - y, height - 1 - x),
_ => (x, y),
};
if y_invert {
sy = height - 1 - sy;
}
let src = sy as usize * stride as usize + sx as usize * 4;
let dst = y as usize * row + x as usize * 4;
pixels[dst..dst + 4].copy_from_slice(&source[src..src + 4]);
}
}
(out_width, out_height)
}
fn buffer_size(width: u32, height: u32, stride: u32) -> Result<usize, String> {
let row = width.checked_mul(4).ok_or("Capture dimensions overflow")?;
let bytes = stride
.checked_mul(height)
.ok_or("Capture dimensions overflow")?;
if width == 0 || height == 0 || stride < row || bytes > 128 * 1024 * 1024 {
return Err("Unsupported capture dimensions".into());
}
Ok(bytes as usize)
}
impl Dispatch<wayland_client::protocol::wl_callback::WlCallback, Arc<AtomicBool>> for State {
fn event(
_: &mut Self,
_: &wayland_client::protocol::wl_callback::WlCallback,
_: wayland_client::protocol::wl_callback::Event,
done: &Arc<AtomicBool>,
_: &Connection,
_: &QueueHandle<Self>,
) {
done.store(true, Ordering::Relaxed);
}
}
wayland_client::delegate_noop!(State: ignore wl_shm::WlShm);
wayland_client::delegate_noop!(State: ignore wl_shm_pool::WlShmPool);
wayland_client::delegate_noop!(State: ignore wl_buffer::WlBuffer);
wayland_client::delegate_noop!(State: ignore manager::ZwlrScreencopyManagerV1);
impl Dispatch<window_manager::FereseWindowCaptureManagerV1, ()> for State {
fn event(
state: &mut Self,
_: &window_manager::FereseWindowCaptureManagerV1,
event: window_manager::Event,
_: &(),
_: &Connection,
_: &QueueHandle<Self>,
) {
match event {
window_manager::Event::Geometry { width, height, .. } => {
state.logical_size = Some((width, height))
}
window_manager::Event::Busy { .. } => state.busy = true,
_ => (),
}
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn capture_orientation_matches_presentation_for_all_transforms() {
use wl_output::Transform::*;
// Asymmetric 3x2 image with row padding and distinct four-byte pixels.
let cases = [
(Normal, (3, 2), "abcdef"),
(_90, (2, 3), "daebfc"),
(_180, (3, 2), "fedcba"),
(_270, (2, 3), "cfbead"),
(Flipped, (3, 2), "cbafed"),
(Flipped90, (2, 3), "adbecf"),
(Flipped180, (3, 2), "defabc"),
(Flipped270, (2, 3), "fcebda"),
];
let pixel = |value: u8| [value, value + 1, value + 2, 255];
let mut pixels = vec![0; 100];
for (transform, size, expected) in cases {
for y_invert in [false, true] {
let mut source = Vec::new();
let rows = if y_invert {
[b"def", b"abc"]
} else {
[b"abc", b"def"]
};
for row in rows {
for &value in row {
source.extend_from_slice(&pixel(value));
}
source.extend_from_slice(&[0; 4]);
}
assert_eq!(
copy_oriented_pixels(&source, 3, 2, 16, transform, y_invert, &mut pixels),
size,
);
let expected: Vec<_> = expected.bytes().flat_map(pixel).collect();
assert_eq!(pixels, expected, "{transform:?}, YInvert={y_invert}");
}
}
}
#[test]
fn rejects_unbounded_and_invalid_buffers() {
assert_eq!(buffer_size(640, 480, 2560).unwrap(), 1228800);
assert!(buffer_size(640, 480, 12).is_err());
assert!(buffer_size(0, 480, 0).is_err());
assert!(buffer_size(u32::MAX, 2, u32::MAX).is_err());
assert!(buffer_size(20000, 20000, 80000).is_err());
}
}