ft-layout crashed - and so did arranging the screens - whenever the row
setting in the layout preset is above what the screens fill. plan()
builds a grid with cols = ceil(count / rows) columns; when that leaves
fewer full rows than the setting asked for, the extra rows are empty,
and the per-row height max() over an empty row raised
ValueError: max() arg is an empty sequence
at plan, line 300 (flat) and 312 (curved)
The smallest real case is 4 screens with 3 rows: cols = ceil(4/3) = 2,
the first two rows hold all 4 screens, the third row is empty. Both the
flat wall and the curved preset crashed, so apply, plan and the
auto-arrange at desktop start all failed until the row setting was
lowered. The Rows spinner in Frametop Display Settings (main.qml) allows
any row count up to the screen count, and clamping to the screen count
does not prevent this - 3 rows for 4 screens is within that range and
never fits a full grid - so the crash was reachable from the UI as
shipped.
Reproduced by calling plan() directly with 4 screens and 3 rows: both
kinds raised. Also verified the whole placement matrix (counts 1-10,
rows 1-4) places every screen after the fix.
The fix trims rows to the number of rows the screens actually fill,
rows = ceil(count / cols), after cols is computed. The row count is
used again for stacking (gap times rows - 1, the sum of row heights),
so the stacking matches the trimmed grid: no empty row is ever built,
and a rows setting that can't be honoured degrades to the tightest fit
instead of failing.
(cherry picked from commit f2bdbd97a0)
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
One bad datagram on the control socket ended the whole relay. Its
dispatch in handle_control ran unguarded in the main loop, so any
exception propagated out of main() and the process exited. The simplest
trigger is "watch abc": float(words[1]) raises ValueError, and the relay
died with
ValueError: could not convert string to float: 'abc'
at handle_control, via the bare handle_control(now) call in the
select loop
The control socket is an abstract socket bound to @frametop_relay.
Abstract sockets carry no permissions, so every local process can send
to it; nothing authenticates the sender. Dying from a datagram was bad
in three ways:
- Every grab is lost. Physical devices go back to gamescope and SteamVR,
which read them themselves, so the mouse types into Steam and the
desktop at once, and Meta+Shift shortcuts fire on both sides.
- The volume-key takeover is lost. gamescope aborts on a volume key when
no window has keyboard focus (wlr_seat_keyboard_notify_enter asserts on
a null focus surface), which ends the whole VR session - the exact
failure the relay exists to prevent.
- systemd restarts the service, but Type=notify with READY only after
the virtual devices exist makes the restart a visible hiccup, and a
crash loop from repeated bad datagrams would flap SteamVR's input.
Reproduced by running the relay with stubbed uinput devices on a
non-Linux host and sending "watch abc" to the control socket: it exited
on the first datagram after answering "devices" correctly. After the
fix, the same exchange gets a log line ("bad control datagram ...") and
the relay keeps answering.
The fix wraps each datagram's dispatch in try/except inside
handle_control's loop, so one malformed message is logged and skipped
while the rest of the queue is still processed. Parsing of the common
helper commands (vrbtn, vrhello, gazeawake, keyboard) keeps its own
guards; the catch-all is only a backstop for anything the guards miss,
including float() on a non-numeric argument to "watch" and "vrcapture".
Adapted for experimental (from PR #8): the guard also wraps the textfield
command, which experimental added to this dispatch after the PR's base.
(cherry picked from commit ca7e58069b)
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
