leyoda/cosmic-greeter
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Fix race condition when getting login session

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If `org.freedesktop.login1.Manager.GetSessionByPID` is called after
cosmic-session puts it in a new systemd scope, it will no longer find
the login session as it would have been removed out of the login session
scope.

Most of the time, cosmic-greeter gets to that line before the scope is
changed, but sometimes (particularly on slower systems or virtual
machines) this race can be lost and lead to cosmic-greeter failing to
start and preventing lockscreen from working.

This commit solves that race condition by always checking the parent PID
instead (which would be cosmic-session which is always present in the
login session scope), and all POSIX-y systems should support using parent
PID.
This commit is contained in:
Lily Foster 2024-09-22 17:04:23 -04:00
parent 55c02cdca9
commit a114971a67
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GPG key ID: 49340081E484C893
1 changed files with 2 additions and 2 deletions
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4
src/logind.rs
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@ -6,7 +6,7 @@ use logind_zbus::{
manager::{InhibitType, ManagerProxy}, manager::{InhibitType, ManagerProxy},
session::SessionProxy, session::SessionProxy,
}; };
use std::{any::TypeId, error::Error, os::fd::OwnedFd, process, sync::Arc}; use std::{any::TypeId, error::Error, os::fd::OwnedFd, sync::Arc};
use tokio::time; use tokio::time;
use zbus::Connection; use zbus::Connection;
@ -68,7 +68,7 @@ pub fn subscription() -> Subscription<Message> {
pub async fn handler(msg_tx: &mut mpsc::Sender<Message>) -> Result<(), Box<dyn Error>> { pub async fn handler(msg_tx: &mut mpsc::Sender<Message>) -> Result<(), Box<dyn Error>> {
let connection = Connection::system().await?; let connection = Connection::system().await?;
let manager = ManagerProxy::new(&connection).await?; let manager = ManagerProxy::new(&connection).await?;
let session_path = manager.get_session_by_PID(process::id()).await?; let session_path = manager.get_session_by_PID(std::os::unix::process::parent_id()).await?;
let session = SessionProxy::builder(&connection) let session = SessionProxy::builder(&connection)
.path(&session_path)? .path(&session_path)?
.build() .build()