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Fix crash when dropping removed token
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This fixes an issue where calloop would crash internally when the
`PostAction::Drop` was invoked after the user manually cancelled the
source in the callback.
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@chrisduerr
chrisduerr committed Oct 3, 2023
1 parent 7ae6f36 commit 1108897
Showing 1 changed file with 88 additions and 81 deletions.
169 changes: 88 additions & 81 deletions src/loop_logic.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ use std::future::Future;

use slab::Slab;

use log::trace;
use log::{debug, trace, warn};

use crate::sources::{Dispatcher, EventSource, Idle, IdleDispatcher};
use crate::sys::{Notifier, PollEvent};
Expand Down Expand Up @@ -260,7 +260,7 @@ impl<'l, Data> LoopHandle<'l, Data> {
.borrow_mut(),
token,
) {
log::warn!(
warn!(
"[calloop] Failed to unregister source from the polling system: {:?}",
e
);
Expand Down Expand Up @@ -419,98 +419,105 @@ impl<'l, Data> EventLoop<'l, Data> {
.get(registroken_token)
.cloned();

if let Some(disp) = opt_disp {
trace!(
"[calloop] Dispatching events for source #{}",
registroken_token
);
let mut ret = disp.process_events(event.readiness, event.token, data)?;

// if the returned PostAction is Continue, it may be overwritten by an user-specified pending action
let pending_action = self
.handle
.inner
.pending_action
.replace(PostAction::Continue);
if let PostAction::Continue = ret {
ret = pending_action;
let disp = match opt_disp {
Some(disp) => disp,
None => {
debug!(
"[calloop] Received an event for non-existent source: {:?}",
registroken_token
);
continue;
}
};

match ret {
PostAction::Reregister => {
trace!(
"[calloop] Postaction reregister for source #{}",
registroken_token
);
disp.reregister(
&mut self.handle.inner.poll.borrow_mut(),
&mut self
.handle
.inner
.sources_with_additional_lifecycle_events
.borrow_mut(),
&mut TokenFactory::new(registroken_token),
)?;
}
PostAction::Disable => {
trace!(
"[calloop] Postaction unregister for source #{}",
registroken_token
);
disp.unregister(
&mut self.handle.inner.poll.borrow_mut(),
&mut self
.handle
.inner
.sources_with_additional_lifecycle_events
.borrow_mut(),
RegistrationToken::new(registroken_token),
)?;
}
PostAction::Remove => {
trace!(
"[calloop] Postaction remove for source #{}",
registroken_token
);
// delete the source from the list, it'll be cleaned up with the if just below
self.handle
trace!(
"[calloop] Dispatching events for source #{}",
registroken_token
);
let mut ret = disp.process_events(event.readiness, event.token, data)?;

// if the returned PostAction is Continue, it may be overwritten by an user-specified pending action
let pending_action = self
.handle
.inner
.pending_action
.replace(PostAction::Continue);
if let PostAction::Continue = ret {
ret = pending_action;
}

match ret {
PostAction::Reregister => {
trace!(
"[calloop] Postaction reregister for source #{}",
registroken_token
);
disp.reregister(
&mut self.handle.inner.poll.borrow_mut(),
&mut self
.handle
.inner
.sources
.borrow_mut()
.remove(registroken_token);
}
PostAction::Continue => {}
.sources_with_additional_lifecycle_events
.borrow_mut(),
&mut TokenFactory::new(registroken_token),
)?;
}

if !self
.handle
.inner
.sources
.borrow()
.contains(registroken_token)
{
// the source has been removed from within its callback, unregister it
let mut poll = self.handle.inner.poll.borrow_mut();
if let Err(e) = disp.unregister(
&mut poll,
PostAction::Disable => {
trace!(
"[calloop] Postaction unregister for source #{}",
registroken_token
);
disp.unregister(
&mut self.handle.inner.poll.borrow_mut(),
&mut self
.handle
.inner
.sources_with_additional_lifecycle_events
.borrow_mut(),
RegistrationToken::new(registroken_token),
) {
log::warn!(
"[calloop] Failed to unregister source from the polling system: {:?}",
e
)?;
}
PostAction::Remove => {
trace!(
"[calloop] Postaction remove for source #{}",
registroken_token
);

// Delete the source from the list, unregister is performed separately.
let mut sources = self.handle.inner.sources.borrow_mut();
if sources.try_remove(registroken_token).is_none() {
debug!(
"[calloop] could not remove event source #{}: token does not exist",
registroken_token
);
}
}
} else {
log::warn!(
"[calloop] Received an event for non-existence source: {:?}",
registroken_token
);
PostAction::Continue => {}
}

if !self
.handle
.inner
.sources
.borrow()
.contains(registroken_token)
{
// the source has been removed from within its callback, unregister it
let mut poll = self.handle.inner.poll.borrow_mut();
if let Err(e) = disp.unregister(
&mut poll,
&mut self
.handle
.inner
.sources_with_additional_lifecycle_events
.borrow_mut(),
RegistrationToken::new(registroken_token),
) {
warn!(
"[calloop] Failed to unregister source from the polling system: {:?}",
e
);
}
}
}

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