Crash in input-method-v1 when restarting fcitx5

[lilydjwg]

Describe the bug

To Reproduce
Steps to reproduce the behavior:

1. Enable plugin input-method-v1
2. In a terminal run fcitx5 -r to restart it
3. Wayfire crashes

Expected behavior
No crash.

Screenshots or stacktrace

#0  0x00007f4bbea4f4c5 in wayfire_input_method_v1_context::deactivate (this=0x590eed017c50, im_killed=<optimized out>)
    at ../../../../../../../build/wayfire/plugins/protocols/input-method-v1.cpp:119
#1  0x00007f4bbea54fc1 in wayfire_input_method_v1::reset_current_im_context (this=this@entry=0x590eec9a91b0, im_killed=im_killed@entry=true) at /usr/include/c++/13.2.1/bits/unique_ptr.h:199
#2  0x00007f4bbea5530a in wayfire_input_method_v1::handle_destroy_im (resource=<optimized out>) at ../../../../../../../build/wayfire/plugins/protocols/input-method-v1.cpp:713
#3  0x00007f4bd5d299ba in destroy_resource (element=0x590eeccb33c0, data=data@entry=0x7ffdb7ca2df4, flags=0) at ../wayland-1.22.0/src/wayland-server.c:732
#4  0x00007f4bd5d2a0db in for_each_helper (entries=0x590eec9bb840, data=0x7ffdb7ca2df4, func=0x7f4bd5d29900 <destroy_resource>) at ../wayland-1.22.0/src/wayland-util.c:416
#5  wl_map_for_each (data=0x7ffdb7ca2df4, func=0x7f4bd5d29900 <destroy_resource>, map=0x590eec9bb840) at ../wayland-1.22.0/src/wayland-util.c:430
#6  wl_client_destroy (client=client@entry=0x590eec9bb810) at ../wayland-1.22.0/src/wayland-server.c:928
#7  0x00007f4bd5d2a60e in destroy_client_with_error (reason=<optimized out>, client=<optimized out>) at ../wayland-1.22.0/src/wayland-server.c:325
#8  wl_client_connection_data (fd=<optimized out>, mask=<optimized out>, data=<optimized out>) at ../wayland-1.22.0/src/wayland-server.c:454
#9  0x00007f4bd5d29ae2 in wl_event_loop_dispatch (loop=0x590eebab8e10, timeout=timeout@entry=-1) at ../wayland-1.22.0/src/event-loop.c:1027
#10 0x00007f4bd5d2a2d7 in wl_display_run (display=0x590eebab8d20) at ../wayland-1.22.0/src/wayland-server.c:1493
#11 0x0000590eeb617d49 in main (argc=<optimized out>, argv=<optimized out>) at ../../../../../../../build/wayfire/src/main.cpp:476
(gdb) p this->text_input 
$1 = (wlr_text_input_v3 *) 0x0

Guarding with a null check will leave Enter pressed and repeating in the terminal.

Wayfire version
git. I don't know why it didn't happen in the past when I tested this.

[ammen99]

Oh, this is a stupid bug. text_input is reset on line 99, but then used on line 119. Can you try moving it around to see whether the bug is resovled?

[ammen99]

Also I'd expect it would be hard to trigger the bug reliably (for ex. in a test) because it depends on a particular race condition, as the comment on line 115-116 explains.

[lilydjwg]

Can you try moving it around to see whether the bug is resovled?

Yes, this bug seems to be resolved, but it crashed elsewhere once (corrupted double-linked list in surface_apply_damage -> wlr_client_buffer_create; I'll file a new bug for it if I can reproduce).