Crashes with EMFILE (too many open files) due to Wayland connection fd leak in WlrClipboard

[halfcrazy]

Bug Description

The process crashes after ~5-6 minutes with EMFILE (too many open files) when running under GNOME Wayland. The crash repeats with consistent timing until the parent process gives up.

Environment

• OS: Linux (Manjaro)
• Compositor: GNOME Wayland
• Clipboards: WlrClipboard (wayland-1) + X11Clipboard (:1)
• ulimit -n: 1024

Error

thread 'main' panicked at wayland-client-0.29.4/src/rust_imp/proxy.rs:211:39:
Sending a message failed.: EMFILE

Root Cause

WlrClipboard::get() and WlrClipboard::set() (src/clipboard.rs) call wl_clipboard_rs::paste::get_contents() and wl_clipboard_rs::copy::Options::copy() respectively. Each call opens a new Wayland connection (socket fd + shm fds), and these connections/fds are not properly cleaned up before the next call.

The polling loop in keep_synced() / await_change() (src/sync.rs) calls get() every 200ms per clipboard, and every clipboard change triggers set() on all clipboards. With 2 clipboards this creates ~10+ Wayland connections per second, leaking fds each time, exhausting the fd limit within ~5-6 minutes.

Relevant Code

• src/clipboard.rs:60-81 — WlrClipboard::get() creates a new Wayland connection per call
• src/clipboard.rs:83-98 — WlrClipboard::set() creates a new Wayland connection per call
• src/sync.rs:246-261 — await_change() polls via get() every 200ms
• src/sync.rs:61-72 — keep_synced() calls set() on all clipboards on every change

Proposed Fix

Use WlCommandClipboard (already implemented in src/clipboard.rs:102-134 as a fallback) as the primary Wayland clipboard backend instead of WlrClipboard. It uses wl-paste/wl-copy subprocesses which clean up after themselves, avoiding the fd leak entirely. This requires:

1. Changing WlCommandClipboard::should_poll() to return true
2. Switching get_wayland() to prefer WlCommandClipboard

Crash Timeline

Each restart survives consistently ~5-6 minutes before hitting EMFILE:

Start	Crash	Uptime
14:50:44	14:56:17	~5.5 min
14:56:18	15:01:39	~5.3 min
15:01:40	15:07:14	~5.5 min
15:07:15	15:12:42	~5.5 min

Full Logs

Details

2026-07-06 14:50:44 -  INFO - started clipboard sync manager
2026-07-06 14:50:44 -  INFO - starting clipboard sync
Invalid MIT-MAGIC-COOKIE-1 key
2026-07-06 14:50:44 -  WARN - Issue connecting to some x11 clipboards. This is expected when hooking up to gnome wayland, and not a problem in that context. Details: 'clipboard error: X11 clipboard error : XCB connection error: Connection' for x11 displays: [0, 2..254]
2026-07-06 14:50:44 -  INFO - Using clipboards: [WlrClipboard { display: "wayland-1" }, X11Clipboard { display: ":1" }]

2026-07-06 14:50:51 -  INFO - clipboard updated from display :1
2026-07-06 14:51:33 -  INFO - clipboard updated from display wayland-1
2026-07-06 14:51:36 -  INFO - clipboard updated from display wayland-1
2026-07-06 14:52:26 -  INFO - clipboard updated from display wayland-1
2026-07-06 14:52:32 -  INFO - clipboard updated from display wayland-1
2026-07-06 14:55:47 -  INFO - clipboard updated from display :1
2026-07-06 14:55:55 -  INFO - clipboard updated from display wayland-1
2026-07-06 14:56:12 -  INFO - clipboard updated from display :1
2026-07-06 14:56:15 -  INFO - clipboard updated from display :1

thread 'main' (31697) panicked at /build/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/wayland-client-0.29.4/src/rust_imp/proxy.rs:211:39:
Sending a message failed.: EMFILE
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
2026-07-06 14:56:17 - FATAL - child process 31697 panicked. giving it another try
2026-07-06 14:56:18 -  INFO - starting clipboard sync
Invalid MIT-MAGIC-COOKIE-1 key
2026-07-06 14:56:18 -  WARN - Issue connecting to some x11 clipboards. This is expected when hooking up to gnome wayland, and not a problem in that context. Details: 'clipboard error: X11 clipboard error : XCB connection error: Connection' for x11 displays: [0, 2..254]
2026-07-06 14:56:18 -  INFO - Using clipboards: [WlrClipboard { display: "wayland-1" }, X11Clipboard { display: ":1" }]
2026-07-06 14:56:23 -  INFO - clipboard updated from display :1
2026-07-06 14:57:44 -  INFO - clipboard updated from display :1
2026-07-06 14:59:58 -  INFO - clipboard updated from display wayland-1
2026-07-06 15:00:23 -  INFO - clipboard updated from display wayland-1
2026-07-06 15:00:30 -  INFO - clipboard updated from display wayland-1
2026-07-06 15:00:44 - ERROR - error getting status of child process 31697: ECHILD: No child processes
2026-07-06 15:00:44 - ERROR - error killing child process 31697: ESRCH: No such process

thread 'main' (32766) panicked at /build/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/wayland-client-0.29.4/src/rust_imp/proxy.rs:211:39:
Sending a message failed.: EMFILE
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
2026-07-06 15:01:39 - FATAL - child process 32766 panicked. giving it another try

(repeats 4 times total)

thread 'main' (31696) panicked at src/main.rs:81:25:
child process 34966 panicked too many times.