noson-gui crashes (SIGABRT) when MPRIS Pause is received while the Sonos speaker is unreachable

[aratuk]

Summary
noson-gui aborts (SIGABRT) when an MPRIS Pause command arrives (e.g. sent automatically by the desktop environment on system suspend) while the target Sonos speaker's socket connection is not immediately available. The main/UI thread makes a synchronous, blocking HTTP request to the speaker in response to the D-Bus call, with no exception handling around the network/socket layer.

Environment
OS: Fedora Linux (aarch64 — Fedora Asahi Remix)
Kernel/arch: aarch64
Desktop environment: KDE Plasma
Trigger: Laptop lid closed → systemd-logind initiates suspend → Plasma's PowerDevil sends an MPRIS Pause command to all detected media players (including noson-gui) via its "Pause media players when suspending" feature
Relevant packages at crash time (from coredump): Qt 6.11.1, KF6 6.28.x libraries, libNosonApp

Steps to Reproduce

1. Run noson-gui connected to a Sonos speaker.
2. Start or leave playback active/available on the speaker.
3. Close the laptop lid (or otherwise trigger a system suspend) on a KDE Plasma session with "Pause media players when suspending" enabled.
4. PowerDevil sends an MPRIS Pause D-Bus call to noson-gui.
5. noson-gui crashes with SIGABRT before/during suspend.

Actual Behavior
The process aborts. Systemd coredump shows the abort occurring on the main thread while it was in the middle of an HTTP request to the speaker:

#3  __select (libc.so.6)
#4  SONOS::TcpSocket::ReceiveData
#5  SONOS::WSResponse::ReadHeaderLine
#6  SONOS::WSResponse::_response::GetResponse
#7  SONOS::WSResponse::_response::_response (ctor)
#8  SONOS::WSResponse::init
#9  SONOS::Service::Request
#10 SONOS::AVTransport::Pause
#11 nosonapp::Player::pause
#12 Mpris2Player::qt_metacall
#13 QDBusConnectionPrivate::deliverCall
...
#26 QCoreApplication::exec
#27 main

All other threads in the process are idle/parked (pthread_cond_wait, poll, etc.) at the time of the crash — only the main thread, mid-network-call in response to the MPRIS Pause, is implicated.

[janbar]

Thanks for reporting. I will test it soon.

[janbar]

I tested this case without having the issue. The platform was Kubuntu 26.04 on x86_64 with the following libs:

• Qt 6.10.2-1
• KDE Plasma KF6 6.24.0

The system suspend causes playback to pause, as you mentioned, but it doesn't fail on my setup.

In your case, Abort() is called in internal system call within "select()". Could you post the trace dump for the lines above "#3 __select (libc.so.6)" ? It could be more explicit about the abort cause and where it was triggered.

[aratuk]

Sorry, here is the full tracedump.

PID 24024 (noson-gui).log

[janbar]

The crash seems to be in libc itself. The source depends of the arch and the libc version installed, That is "aarch64" and "Fedora Asahi Remix".

On you system you could type the following command to find the exact function and the line number where it failed:

on Fedora probably:

addr2line -e /lib64/libc.so.6 0x977a8

on debian the command looks like: addr2line -e /lib/aarch64-linux-gnu/libc.so.6 0x977a8

[aratuk]

Hmm:
$ addr2line -f -e /lib64/libc.so.6 0x977a8
__syscall_cancel_arch_start
:?

Tried running with debug logging, and wasn't able to replicate the crash again, which seems it could be due to a different external state, in the Sonos system. I'd be happy to try anything else that might get more info.