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wayland: say which step of the portal handshake failed

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The XDG portal handshake is four sequential requests, and every way it can end
badly -- the user declining, nobody answering, the portal being absent or
ending it or dying mid-handshake, the stream list coming back empty -- left
`request_remote_desktop` through one `bail!` carrying one string.
`map_err_scrap` then guessed a cause by looking for "dbus" or "pipewire" in
that string. Since that string always mentions "PipeWire library", a decline
and a three-minute timeout both came out as "Wayland requires higher version of
linux distro. Please try X11 desktop or change your OS." On Ubuntu 21+, where
the mapping passes the text through untouched, they came out as raw English
pointing at an unrelated GitHub issue.

The response code and the D-Bus error were in hand at the moment of failure and
were being dropped: `handle_response` collapsed all of it into one
`AtomicBool`. Record it instead, tagged with the stage that produced it, and
let the app side look the tag up. `map_err_scrap` gains one leading branch;
anything untagged -- which is everything the capture loop reports -- takes the
existing path unchanged.

The tag decides between five new keys and the existing `xdp-portal-unavailable`:

- A decline, nobody answering, the portal ending the request with its response
  code, an empty stream list, and a missing GStreamer element each get their
  own message. Sentence-case English, so a peer that has never heard of them
  falls back to the key and still reads as a sentence rather than showing a
  slug like `x11 expected`.
- Everything else is the portal failing to deliver, which is what
  `xdp-portal-unavailable` already says -- it is already translated everywhere
  and carries the one remedy a user can act on, `systemctl --user restart
  xdg-desktop-portal`. The D-Bus error name and message go to the log.
- The Ubuntu-before-21 branch keeps every outcome that says something about the
  machine and yields the two that say what a person did.

`fill_displays` needs the tag resolved at its own call site: it opens a second
portal session for cursor-based display disambiguation, and its error returns
straight up `check_init` without passing through `map_err_scrap`, so a tag
would otherwise reach the peer verbatim.

Two existing paths change, both necessarily:

- `check_init` no longer wraps `Capturer::new` in `with_context`. The peer is
  shown `format!("{}", err)` (connection.rs), which renders only the outermost
  layer, so that context was replacing the mapped code with "Failed to create
  capturer for display 0".
- The `std::process::exit(-1)` on libdbus' no-reply text is now reached only by
  the capture loop, which is what that self-heal was written for. A no-reply
  during the handshake is tagged and reported instead. It is worth saying
  plainly what that branch did before: the portal proxy has a one-second
  timeout, so a portal slow to activate could take the whole service down.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EZ49AbZJYfm8NTp5yDPMab
This commit is contained in:
rustdesk
2026-09-08 17:53:59 +08:00
parent e5d473407e
commit 6feb49f060
2 changed files with 352 additions and 32 deletions
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207
libs/scrap/src/wayland/pipewire.rs
View File

@@ -24,7 +24,7 @@ use lazy_static::lazy_static;
use serde::{Deserialize, Serialize};
use base::platform::linux::CMD_SH;
use hbb_common::{bail, config, serde_json, tokio, ResultType};
use hbb_common::{anyhow::anyhow, bail, config, serde_json, tokio, ResultType};
use super::capturable::PixelProvider;
use super::capturable::{Capturable, Recorder};
@@ -264,11 +264,18 @@ pub struct PipeWireRecorder {
saved_raw_data: Vec<u8>, // for faster compare and copy
}
// Element creation fails the same way for a plugin that is not installed as for one that is
// broken, and the name is the only thing that tells a user which package to look at.
fn gst_element(name: &str) -> ResultType<gst::Element> {
gst::ElementFactory::make(name, None)
.map_err(|_| anyhow!(stage_err("gst-plugin", "missing", name)))
}
impl PipeWireRecorder {
pub fn new(capturable: PipeWireCapturable) -> ResultType<Self> {
let pipeline = gst::Pipeline::new(None);
let src = gst::ElementFactory::make("pipewiresrc", None)?;
let src = gst_element("pipewiresrc")?;
src.set_property("fd", &capturable.fd.as_raw_fd())?;
src.set_property("path", &format!("{}", capturable.path))?;
src.set_property("keepalive_time", &1_000.as_raw_fd())?;
@@ -283,9 +290,9 @@ impl PipeWireRecorder {
// "no more output formats" / not-negotiated (-4). videoconvert accepts any
// system-memory video/x-raw format, widening negotiation so the portal can
// settle on a format it can deliver via its SHM path.
let convert = gst::ElementFactory::make("videoconvert", None)?;
let convert = gst_element("videoconvert")?;
let sink = gst::ElementFactory::make("appsink", None)?;
let sink = gst_element("appsink")?;
sink.set_property("drop", &true)?;
sink.set_property("max-buffers", &1u32)?;
@@ -464,11 +471,112 @@ impl Drop for PipeWireRecorder {
}
}
// The portal handshake is four sequential requests whose outcomes arrive as asynchronous
// `Response` signals, so where and why it failed is known only inside the signal handler.
// Recording it here, instead of collapsing every outcome into one `failed` flag, is what lets
// the app side name the real cause rather than guess it from the error text.
#[derive(Clone, Copy)]
enum PortalStage {
CreateSession = 1,
SelectDevices = 2,
SelectSources = 3,
Start = 4,
}
impl PortalStage {
fn as_str(&self) -> &'static str {
match self {
Self::CreateSession => "create-session",
Self::SelectDevices => "select-devices",
Self::SelectSources => "select-sources",
Self::Start => "start",
}
}
fn from_u8(v: u8) -> Self {
match v {
2 => Self::SelectDevices,
3 => Self::SelectSources,
4 => Self::Start,
_ => Self::CreateSession,
}
}
}
// `wl-stage:<stage>:<kind>:<detail>`, parsed by `map_err_scrap` on the app side. The detail
// reaches the user through a `{}` placeholder in a translated string, so it must not bring
// braces, control characters or unbounded length of its own.
fn stage_err(stage: &str, kind: &str, detail: &str) -> String {
let detail: String = detail
.chars()
.map(|c| if c.is_control() { ' ' } else { c })
.filter(|c| *c != '{' && *c != '}')
.take(200)
.collect();
format!("wl-stage:{}:{}:{}", stage, kind, detail.trim())
}
fn dbus_detail(err: &dbus::Error) -> String {
match (err.name(), err.message()) {
(Some(name), Some(message)) if !name.is_empty() && !message.is_empty() => {
format!("{}: {}", name, message)
}
(Some(name), _) if !name.is_empty() => name.to_owned(),
(_, message) => message.unwrap_or_default().to_owned(),
}
}
#[derive(Clone)]
struct PortalTrace {
failed: Arc<AtomicBool>,
reason: Arc<Mutex<Option<String>>>,
// The stage whose `Response` we are still waiting for, so the polling loop can tell a
// non-interactive step apart from the one that waits for a human.
waiting_for: Arc<AtomicU8>,
}
impl PortalTrace {
fn new() -> Self {
Self {
failed: Arc::new(AtomicBool::new(false)),
reason: Arc::new(Mutex::new(None)),
waiting_for: Arc::new(AtomicU8::new(PortalStage::CreateSession as u8)),
}
}
fn fail(&self, stage: PortalStage, kind: &str, detail: &str) {
self.record(stage_err(stage.as_str(), kind, detail));
self.failed.store(true, Ordering::SeqCst);
}
// The first failure is the cause; whatever follows it is a consequence.
fn record(&self, tag: String) {
if let Ok(mut reason) = self.reason.lock() {
if reason.is_none() {
*reason = Some(tag);
}
}
}
fn waiting(&self, stage: PortalStage) {
self.waiting_for.store(stage as u8, Ordering::SeqCst);
}
fn waiting_stage(&self) -> PortalStage {
PortalStage::from_u8(self.waiting_for.load(Ordering::SeqCst))
}
fn take_reason(&self) -> Option<String> {
self.reason.lock().ok().and_then(|mut r| r.take())
}
}
fn handle_response<F>(
conn: &SyncConnection,
path: dbus::Path<'static>,
mut f: F,
failure_out: Arc<AtomicBool>,
trace: PortalTrace,
stage: PortalStage,
) -> Result<dbus::channel::Token, dbus::Error>
where
F: FnMut(
@@ -491,18 +599,18 @@ where
0 => {}
1 => {
warn!("DBus response: User cancelled interaction.");
failure_out.store(true, Ordering::SeqCst);
trace.fail(stage, "declined", "");
return true;
}
c => {
warn!("DBus response: Unknown error, code: {}.", c);
failure_out.store(true, Ordering::SeqCst);
trace.fail(stage, "portal-error", &c.to_string());
return true;
}
}
if let Err(err) = f(r, c, m) {
warn!("Error requesting screen capture via dbus: {}", err);
failure_out.store(true, Ordering::SeqCst);
trace.fail(trace.waiting_stage(), "internal", &err.to_string());
}
true
})
@@ -638,15 +746,16 @@ pub fn request_remote_desktop(
INIT = true;
}
}
let conn = SyncConnection::new_session()?;
let conn = SyncConnection::new_session()
.map_err(|e| anyhow!(stage_err("session-bus", "dbus", &dbus_detail(&e))))?;
let portal = get_portal(&conn);
let mut args: PropMap = HashMap::new();
let fd: Arc<Mutex<Option<OwnedFd>>> = Arc::new(Mutex::new(None));
let fd_res = fd.clone();
let streams: Arc<Mutex<Vec<PwStreamInfo>>> = Arc::new(Mutex::new(Vec::new()));
let streams_res = streams.clone();
let failure = Arc::new(AtomicBool::new(false));
let failure_res = failure.clone();
let trace = PortalTrace::new();
let trace_res = trace.clone();
let session: Arc<Mutex<Option<dbus::Path>>> = Arc::new(Mutex::new(None));
let session_res = session.clone();
let create_session_handle_token = "u1";
@@ -679,16 +788,19 @@ pub fn request_remote_desktop(
fd.clone(),
streams.clone(),
session.clone(),
failure.clone(),
trace.clone(),
is_support_restore_token,
capture_cursor,
),
failure_res.clone(),
trace.clone(),
PortalStage::CreateSession,
)?;
if is_server_running() {
let _ = screencast_portal::create_session(&portal, args)?;
let _ = screencast_portal::create_session(&portal, args)
.map_err(|e| anyhow!(stage_err("create-session", "dbus", &dbus_detail(&e))))?;
} else {
let _ = remote_desktop_portal::create_session(&portal, args)?;
let _ = remote_desktop_portal::create_session(&portal, args)
.map_err(|e| anyhow!(stage_err("create-session", "dbus", &dbus_detail(&e))))?;
}
// wait 3 minutes for user interaction
@@ -699,13 +811,14 @@ pub fn request_remote_desktop(
break;
}
if failure_res.load(Ordering::SeqCst) {
if trace_res.failed.load(Ordering::SeqCst) {
break;
}
}
let fd_res = fd_res.lock().unwrap();
let streams_res = streams_res.lock().unwrap();
let session_res = session_res.lock().unwrap();
let have_fd = fd_res.is_some();
if let Some(fd_res) = fd_res.clone() {
if let Some(session) = session_res.clone() {
@@ -720,14 +833,20 @@ pub fn request_remote_desktop(
}
}
}
bail!("Failed to obtain screen capture. You may need to upgrade the PipeWire library for better compatibility. Please check https://github.com/rustdesk/rustdesk/issues/8600#issuecomment-2254720954 for more details.")
bail!(trace_res.take_reason().unwrap_or_else(|| {
if have_fd {
stage_err("streams", "empty", "")
} else {
stage_err(trace_res.waiting_stage().as_str(), "no-response", "")
}
}))
}
fn on_create_session_response(
fd: Arc<Mutex<Option<OwnedFd>>>,
streams: Arc<Mutex<Vec<PwStreamInfo>>>,
session: Arc<Mutex<Option<dbus::Path<'static>>>>,
failure: Arc<AtomicBool>,
trace: PortalTrace,
is_support_restore_token: bool,
capture_cursor: bool,
) -> impl Fn(
@@ -793,12 +912,14 @@ fn on_create_session_response(
on_select_sources_response(
fd.clone(),
streams.clone(),
failure.clone(),
trace.clone(),
ses.clone(),
is_support_restore_token,
),
failure.clone(),
trace.clone(),
PortalStage::SelectSources,
)?;
trace.waiting(PortalStage::SelectSources);
let _ = portal.select_sources(ses.clone(), args)?;
} else {
// TODO: support persist_mode for remote_desktop_portal
@@ -817,12 +938,14 @@ fn on_create_session_response(
on_select_devices_response(
fd.clone(),
streams.clone(),
failure.clone(),
trace.clone(),
ses.clone(),
is_support_restore_token,
),
failure.clone(),
trace.clone(),
PortalStage::SelectDevices,
)?;
trace.waiting(PortalStage::SelectDevices);
let _ = portal.select_devices(ses.clone(), args)?;
}
@@ -833,7 +956,7 @@ fn on_create_session_response(
fn on_select_devices_response(
fd: Arc<Mutex<Option<OwnedFd>>>,
streams: Arc<Mutex<Vec<PwStreamInfo>>>,
failure: Arc<AtomicBool>,
trace: PortalTrace,
session: dbus::Path<'static>,
is_support_restore_token: bool,
) -> impl Fn(
@@ -862,12 +985,14 @@ fn on_select_devices_response(
on_select_sources_response(
fd.clone(),
streams.clone(),
failure.clone(),
trace.clone(),
session.clone(),
is_support_restore_token,
),
failure.clone(),
trace.clone(),
PortalStage::SelectSources,
)?;
trace.waiting(PortalStage::SelectSources);
let _ = portal.select_sources(session.clone(), args)?;
Ok(())
@@ -877,7 +1002,7 @@ fn on_select_devices_response(
fn on_select_sources_response(
fd: Arc<Mutex<Option<OwnedFd>>>,
streams: Arc<Mutex<Vec<PwStreamInfo>>>,
failure: Arc<AtomicBool>,
trace: PortalTrace,
session: dbus::Path<'static>,
is_support_restore_token: bool,
) -> impl Fn(
@@ -902,8 +1027,10 @@ fn on_select_sources_response(
session.clone(),
is_support_restore_token,
),
failure.clone(),
trace.clone(),
PortalStage::Start,
)?;
trace.waiting(PortalStage::Start);
if is_server_running() {
let _ = screencast_portal::start(&portal, session.clone(), "", args)?;
} else {
@@ -1555,3 +1682,29 @@ fn sort_streams(
*streams = sorted_streams;
*shared_displays = sorted_shared_displays;
}
#[cfg(test)]
mod tests {
use super::stage_err;
#[test]
fn stage_err_keeps_the_detail_safe_for_a_placeholder() {
assert_eq!(
stage_err("start", "declined", ""),
"wl-stage:start:declined:"
);
// Braces of its own would break the placeholder lookup on the peer.
assert_eq!(
stage_err("create-session", "dbus", "org.freedesktop.{Error}"),
"wl-stage:create-session:dbus:org.freedesktop.Error"
);
assert_eq!(
stage_err("select-sources", "internal", "one\ntwo"),
"wl-stage:select-sources:internal:one two"
);
assert_eq!(
stage_err("start", "internal", &"x".repeat(300)),
format!("wl-stage:start:internal:{}", "x".repeat(200))
);
}
}

177
src/server/wayland.rs
View File

@@ -21,6 +21,7 @@ lazy_static::lazy_static! {
static ref CAP_DISPLAY_INFO: RwLock<HashMap<usize, u64>> = RwLock::new(HashMap::new());
static ref PIPEWIRE_INITIALIZED: RwLock<bool> = RwLock::new(false);
static ref LOG_SCRAP_COUNT: Mutex<u32> = Mutex::new(0);
static ref LAST_STAGE_ERR: Mutex<String> = Mutex::new(String::new());
static ref ACTIVE_DISPLAY_COUNT: RwLock<usize> = RwLock::new(0);
}
@@ -44,11 +45,23 @@ pub(super) fn decrement_active_display_count() -> usize {
fn map_err_scrap(err: String) -> io::Error {
// to-do: Handle error better, do not restart server
// Reached by the capture loop, which is what this crude self-heal was for. A no-reply
// during the portal handshake is tagged below and is reported instead of exiting: at
// login there is someone waiting to be told, and a portal that is slow to activate is
// not a reason to take the service down.
if err.starts_with("Did not receive a reply") {
log::error!("Fatal pipewire error, {}", &err);
std::process::exit(-1);
}
if let Some(tag) = err.strip_prefix(WAYLAND_STAGE_TAG) {
log_staged_once(&err);
return io::Error::new(
io::ErrorKind::Other,
staged_message(tag, is_ubuntu_before_21()),
);
}
if DISTRO.name.to_uppercase() == "Ubuntu".to_uppercase() {
if DISTRO.version_id < "21".to_owned() {
io::Error::new(io::ErrorKind::Other, SCRAP_UBUNTU_HIGHER_REQUIRED)
@@ -74,6 +87,28 @@ fn map_err_scrap(err: String) -> io::Error {
}
}
/// `Display::all` and `Capturer::new` reach the peer through `map_err_scrap`, but
/// `fill_displays` opens a portal session of its own and returns its error straight up, so a
/// tag has to be resolved here or it lands in the login dialog verbatim.
fn map_staged_err(err: anyhow::Error) -> anyhow::Error {
let text = err.to_string();
match text.strip_prefix(WAYLAND_STAGE_TAG) {
Some(tag) => {
log_staged_once(&text);
anyhow::anyhow!(staged_message(tag, is_ubuntu_before_21()))
}
None => err,
}
}
fn log_staged_once(err: &str) {
let mut last = LAST_STAGE_ERR.lock().unwrap();
if *last != err {
log::error!("Wayland portal handshake failed: {}", err);
*last = err.to_owned();
}
}
fn try_log(err: &String) {
let mut lock_count = LOG_SCRAP_COUNT.lock().unwrap();
if *lock_count >= 1000000 {
@@ -85,6 +120,138 @@ fn try_log(err: &String) {
*lock_count += 1;
}
// Translation keys, so the key itself is the English text: an older peer that has never heard
// of them falls back to displaying the key and still reads as a sentence.
const WAYLAND_DECLINED: &str = "The screen sharing request was declined on the remote device";
const WAYLAND_NO_ANSWER: &str =
"No one responded to the screen sharing request on the remote device";
const WAYLAND_PORTAL_ENDED: &str = "The XDG Desktop Portal ended the screen sharing request ({})";
// The remedy the message it replaces used to carry, minus the link: this is the outcome
// rustdesk/rustdesk#8600 is about.
const WAYLAND_NO_SCREEN: &str =
"The XDG Desktop Portal returned no screen to capture, the PipeWire library may be too old";
const WAYLAND_GST_MISSING: &str = "A GStreamer plugin needed for screen capture is missing ({})";
const WAYLAND_STAGE_TAG: &str = "wl-stage:";
// `translate()` on the peer strips the braces itself, so what goes on the wire is the key
// with the detail still *inside* the placeholder.
fn with_detail(key: &str, detail: &str) -> String {
key.replace("{}", &format!("{{{}}}", detail))
}
fn is_ubuntu_before_21() -> bool {
DISTRO.name.to_uppercase() == "Ubuntu".to_uppercase() && DISTRO.version_id < "21".to_owned()
}
/// Maps a `<stage>:<kind>:<detail>` tag from the portal handshake, see
/// `scrap::wayland::pipewire`, onto what to tell the peer. Everything the capture loop reports
/// carries no tag and keeps the legacy substring heuristics above.
fn staged_message(tag: &str, ubuntu_before_21: bool) -> String {
let mut parts = tag.splitn(3, ':');
let stage = parts.next().unwrap_or_default();
let kind = parts.next().unwrap_or_default();
let detail = parts.next().unwrap_or_default().trim();
// An outcome that says something about the machine is what the Ubuntu branch was written
// for, so that branch keeps it. An outcome that says what a person did is a fact no distro
// check can improve on.
let of_the_machine = |msg: &str| {
if ubuntu_before_21 {
SCRAP_UBUNTU_HIGHER_REQUIRED.to_owned()
} else {
msg.to_owned()
}
};
match (stage, kind) {
(_, "declined") => WAYLAND_DECLINED.to_owned(),
(_, "portal-error") => with_detail(WAYLAND_PORTAL_ENDED, detail),
("start", "no-response") => WAYLAND_NO_ANSWER.to_owned(),
("streams", _) => of_the_machine(WAYLAND_NO_SCREEN),
("gst-plugin", _) => of_the_machine(&with_detail(WAYLAND_GST_MISSING, detail)),
// Everything else is the portal not delivering, which is what this key already says --
// and unlike a message of our own it carries the `systemctl --user restart` remedy.
_ => of_the_machine(SCRAP_XDP_PORTAL_UNAVAILABLE),
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn staged_message_names_the_stage() {
let m = |tag| staged_message(tag, false);
assert_eq!(m("start:declined:"), WAYLAND_DECLINED);
assert_eq!(m("start:no-response:"), WAYLAND_NO_ANSWER);
assert_eq!(m("streams:empty:"), WAYLAND_NO_SCREEN);
}
#[test]
fn a_portal_that_did_not_deliver_keeps_the_message_that_says_how_to_restart_it() {
let m = |tag| staged_message(tag, false);
assert_eq!(
m("create-session:dbus:org.freedesktop.DBus.Error.ServiceUnknown"),
SCRAP_XDP_PORTAL_UNAVAILABLE
);
assert_eq!(
m("create-session:no-response:"),
SCRAP_XDP_PORTAL_UNAVAILABLE
);
assert_eq!(
m("select-sources:internal:no session_handle"),
SCRAP_XDP_PORTAL_UNAVAILABLE
);
// A tag this build does not know must never fall back to a guess.
assert_eq!(
m("some-new-stage:some-new-kind:x"),
SCRAP_XDP_PORTAL_UNAVAILABLE
);
assert_eq!(m(""), SCRAP_XDP_PORTAL_UNAVAILABLE);
}
// The peer resolves a message by replacing its first `{...}` with `{}` and looking that
// up, so every detail-carrying message has to reduce back to its key exactly.
#[test]
fn a_detail_carrying_message_reduces_back_to_its_key() {
let reduce = |s: &str| {
let open = s.find('{').expect("no placeholder");
let close = s[open..].find('}').expect("unclosed placeholder") + open;
format!("{}{{}}{}", &s[..open], &s[close + 1..])
};
let ended = staged_message("start:portal-error:2", false);
assert_eq!(
ended,
"The XDG Desktop Portal ended the screen sharing request ({2})"
);
assert_eq!(reduce(&ended), WAYLAND_PORTAL_ENDED);
let gst = staged_message("gst-plugin:missing:pipewiresrc", false);
assert_eq!(
gst,
"A GStreamer plugin needed for screen capture is missing ({pipewiresrc})"
);
assert_eq!(reduce(&gst), WAYLAND_GST_MISSING);
}
#[test]
fn legacy_ubuntu_keeps_its_message_for_machine_faults_only() {
let m = |tag| staged_message(tag, true);
assert_eq!(
m("create-session:dbus:org.freedesktop.DBus.Error.ServiceUnknown"),
SCRAP_UBUNTU_HIGHER_REQUIRED
);
assert_eq!(
m("gst-plugin:missing:pipewiresrc"),
SCRAP_UBUNTU_HIGHER_REQUIRED
);
assert_eq!(m("streams:empty:"), SCRAP_UBUNTU_HIGHER_REQUIRED);
assert_eq!(m("start:declined:"), WAYLAND_DECLINED);
assert_eq!(m("start:no-response:"), WAYLAND_NO_ANSWER);
}
}
struct CapturerPtr(*mut Capturer);
impl Clone for CapturerPtr {
@@ -312,7 +479,8 @@ pub(super) async fn check_init() -> ResultType<()> {
{
let temp_mouse_move_handle = input_service::TemporaryMouseMoveHandle::new();
let move_mouse_to = |x, y| temp_mouse_move_handle.move_mouse_to(x, y);
fill_displays(move_mouse_to, crate::get_cursor_pos, &mut all)?;
fill_displays(move_mouse_to, crate::get_cursor_pos, &mut all)
.map_err(map_staged_err)?;
}
log::debug!("Attempting to fix logical size with try_fix_logical_size()");
try_fix_logical_size(&mut all);
@@ -340,10 +508,9 @@ pub(super) async fn check_init() -> ResultType<()> {
// Create individual CapDisplayInfo for each display with its own capturer
for (idx, display) in all.into_iter().enumerate() {
let capturer =
Box::into_raw(Box::new(Capturer::new(display).with_context(|| {
format!("Failed to create capturer for display {}", idx)
})?));
// No `with_context` here: the peer is shown `format!("{}", err)`, which
// renders only the outermost layer, and the mapped reason is the inner one.
let capturer = Box::into_raw(Box::new(Capturer::new(display)?));
let capturer = CapturerPtr(capturer);
let cap_display_info = Box::into_raw(Box::new(CapDisplayInfo {