Source code
Revision control
Copy as Markdown
Other Tools
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
use crash_helper_common::{errors::IPCError, ignore_eintr, IPCEvent};
use nix::{
errno::Errno,
poll::{poll, PollFd, PollFlags, PollTimeout},
};
use super::IPCServer;
impl IPCServer {
pub fn wait_for_events(&mut self) -> Result<Vec<IPCEvent>, IPCError> {
let mut pollfds = Vec::with_capacity(1 + self.connections.len());
pollfds.push(PollFd::new(self.listener.as_raw_ref(), PollFlags::POLLIN));
pollfds.extend(
self.connections.iter().map(|connection| {
PollFd::new(connection.connector.as_raw_ref(), PollFlags::POLLIN)
}),
);
let mut events = Vec::<IPCEvent>::new();
let mut num_events =
ignore_eintr!(poll(&mut pollfds, PollTimeout::NONE)).map_err(IPCError::System)?;
for (index, pollfd) in pollfds.iter().enumerate() {
// revents() returns None only if the kernel sends back data
// that nix does not understand, we can safely assume this
// never happens in practice hence the unwrap().
let revents = pollfd.revents().unwrap();
if revents.contains(PollFlags::POLLHUP) {
if index > 0 {
events.push(IPCEvent::Disconnect(index - 1));
// If a process was disconnected then skip all further
// processing of the socket. This wouldn't matter normally,
// but on macOS calling recvmsg() on a hung-up socket seems
// to trigger a kernel panic, one we've already encountered
// in the past. Doing things this way avoids the panic
// while having no real downsides.
continue;
} else {
// This should never happen, unless the listener socket was
// not set up properly or a failure happened during setup.
return Err(IPCError::System(Errno::EFAULT));
}
}
if revents.contains(PollFlags::POLLIN) {
if index == 0 {
if let Ok(connector) = self.listener.accept() {
events.push(IPCEvent::Connect(connector));
}
} else {
// SAFETY: The index is guaranteed to be >0 and within
// the bounds of the connections array.
let connection = unsafe { self.connections.get_unchecked(index - 1) };
let header = connection.connector.recv_header();
if let Ok(header) = header {
// Note that if we encounter a failure we don't propagate
// it, when the socket gets disconnected we'll get a
// POLLHUP event anyway so deal with disconnections there
// instead of here.
events.push(IPCEvent::Header(index - 1, header));
}
}
}
if !revents.is_empty() {
num_events -= 1;
if num_events == 0 {
break;
}
}
}
Ok(events)
}
}