bug#75120: 31.0.50; which-key crashes on xt if the scroll bar is activated.

bug#75120: 31.0.50; which-key crashes on xt if the scroll bar is activated.

[Madhu]

Hello, Having heard about which-key mode I decided to try it.

gdb --args ../build-xt-native/src/emacs  -Q  -eval '(which-key-mode 1)' -eval '(setq window-min-height 8)'

1. type C-x, wait 5 seconds, type C-g.
2. type C-x, wait 2 seconds for the 8 line frame with scrollbar, click the "up
arrow" on the top of the scrollbar.

BEGIN BACKTRACE
read 1 "emacs" received signal SIGSEGV, Segmentation fault.
0x000000000054446b in xt_action_hook (widget=<optimized out>, client_data=<optim
ized out>, action_name=0xe964d3 "EndScroll", event=<optimized out>, params=<opti
mized out>, num_params=<optimized out>) at ../../src/xterm.c:15479
15479         if (bar->dragging != -1)
(gdb) xbacktrace
(gdb) bt full
#0  0x000000000054446b in xt_action_hook (widget=<optimized out>,
    client_data=<optimized out>, action_name=0xe964d3 "EndScroll",
    event=<optimized out>, params=<optimized out>, num_params=<optimized out>)
    at ../../src/xterm.c:15479
        w = 0x1555470
        bar = <optimized out>
        scroll_bar_p = <optimized out>
        end_action = <optimized out>
        scroll_bar_p = <optimized out>
        end_action = <optimized out>
        w = <optimized out>
        bar = <optimized out>
#1  xt_action_hook (widget=<optimized out>, client_data=<optimized out>,
    action_name=0xe964d3 "EndScroll", event=<optimized out>,
    params=<optimized out>, num_params=<optimized out>)
    at ../../src/xterm.c:15453
        scroll_bar_p = <optimized out>
        end_action = 0x6f4dcb "EndScroll"
        w = <optimized out>
        bar = <optimized out>
#2  0x00007ffff7d0a43d in ?? () from /usr/lib64/libXt.so.6
No symbol table info available.
#3  0x0000000000e7ec10 in ?? ()
[...]
(gdb) sharedlibrary .
(gdb) back
#0  0x000000000054446b in xt_action_hook
    (widget=<optimized out>, client_data=<optimized out>, action_name=0xe964d3 "EndScroll", event=<optimized out>, params=<optimized out>, num_params=<optimized out>) at ../../src/xterm.c:15479
#1  xt_action_hook
    (widget=<optimized out>, client_data=<optimized out>, action_name=0xe964d3 "EndScroll", event=<optimized out>, params=<optimized out>, num_params=<optimized out>) at ../../src/xterm.c:15453
#2  0x00007ffff7d0a43d in HandleActions
    (w=w@entry=0x1256750, event=0x7fffffffc5a0, stateTree=0x124a3f0, accelWidget=<optimized out>, procs=0xde6318, actions=actions@entry=0x7ffff7d2a120 <dummyAction.3>) at /usr/src/debug/x11-libs/libXt-1.3.0/libXt-1.3.0/src/TMstate.c:633
#3  0x00007ffff7d0ac91 in HandleSimpleState
    (w=w@entry=0x1256750, tmRecPtr=tmRecPtr@entry=0x1256798, curEventPtr=curEventPtr@entry=0x7fffffffbdd0)
    at /usr/src/debug/x11-libs/libXt-1.3.0/libXt-1.3.0/src/TMstate.c:866
#4  0x00007ffff7d0bb68 in _XtTranslateEvent
    (w=w@entry=0x1256750, event=event@entry=0x7fffffffc5a0)
    at /usr/src/debug/x11-libs/libXt-1.3.0/libXt-1.3.0/src/TMstate.c:1064
#5  0x00007ffff7ce4eeb in XtDispatchEventToWidget
    (widget=widget@entry=0x1256750, event=event@entry=0x7fffffffc5a0)
    at /usr/src/debug/x11-libs/libXt-1.3.0/libXt-1.3.0/src/Event.c:933
#6  0x00007ffff7ce55a2 in _XtDefaultDispatcher (event=0x7fffffffc5a0)
    at /usr/src/debug/x11-libs/libXt-1.3.0/libXt-1.3.0/src/Event.c:1407
--Type <RET> for more, q to quit, c to continue without paging--c
#7  0x00007ffff7ce5701 in XtDispatchEvent (event=event@entry=0x7fffffffc5a0) at /usr/src/debug/x11-libs/libXt-1.3.0/libXt-1.3.0/src/Event.c:1481
#8  0x000000000055b181 in handle_one_xevent (dpyinfo=<optimized out>, event=<optimized out>, finish=<optimized out>, hold_quit=<optimized out>) at ../../src/xterm.c:25578
#9  0x0000000000566d91 in XTread_socket (terminal=<optimized out>, hold_quit=0x7fffffffc690) at ../../src/xterm.c:25740
#10 0x0000000000592341 in gobble_input () at ../../src/keyboard.c:7923
#11 0x0000000000595355 in handle_async_input () at ../../src/keyboard.c:8162
#12 process_pending_signals () at ../../src/keyboard.c:8176
#13 unblock_input_to (level=0) at ../../src/keyboard.c:8191
#14 unblock_input_to (level=<optimized out>) at ../../src/keyboard.c:8185
#15 unblock_input () at ../../src/keyboard.c:8210
#16 0x00000000006cc9d9 in xg_select (fds_lim=<optimized out>, rfds=rfds@entry=0x7fffffffcef0, wfds=<optimized out>, efds=0x0, timeout=<optimized out>, sigmask=<optimized out>) at ../../src/xgselect.c:298
#17 0x0000000000673c96 in wait_reading_process_output (time_limit=time_limit@entry=30, nsecs=nsecs@entry=0, read_kbd=read_kbd@entry=-1, do_display=do_display@entry=true, wait_for_cell=wait_for_cell@entry=XIL(0), wait_proc=wait_proc@entry=0x0, just_wait_proc=0) at ../../src/process.c:5765
#18 0x00000000004759f0 in sit_for (timeout=timeout@entry=make_fixnum(30), reading=reading@entry=true, display_option=display_option@entry=1) at ../../src/dispnew.c:6335
#19 0x000000000059a4e8 in read_char (commandflag=1, map=XIL(0x151af43), prev_event=XIL(0), used_mouse_menu=0x7fffffffd70b, end_time=0x0) at ../../src/keyboard.c:2926
#20 0x000000000059b7ef in read_key_sequence (keybuf=<optimized out>, prompt=XIL(0), dont_downcase_last=false, can_return_switch_frame=true, fix_current_buffer=true, prevent_redisplay=false, disable_text_conversion_p=false) at ../../src/keyboard.c:10747
#21 0x000000000059d446 in command_loop_1 () at ../../src/keyboard.c:1424
#22 0x0000000000613d47 in internal_condition_case (bfun=bfun@entry=0x59d2a0 <command_loop_1>, handlers=handlers@entry=XIL(0x90), hfun=hfun@entry=0x591030 <cmd_error>) at ../../src/eval.c:1607
#23 0x00000000005891ca in command_loop_2 (handlers=handlers@entry=XIL(0x90)) at ../../src/keyboard.c:1163
#24 0x0000000000613ca1 in internal_catch (tag=tag@entry=XIL(0x12390), func=func@entry=0x5891b0 <command_loop_2>, arg=arg@entry=XIL(0x90)) at ../../src/eval.c:1286
#25 0x000000000058916f in command_loop () at ../../src/keyboard.c:1141
#26 0x0000000000590be3 in recursive_edit_1 () at ../../src/keyboard.c:749
#27 0x0000000000590f5e in Frecursive_edit () at ../../src/keyboard.c:832
#28 0x000000000046a7ec in main (argc=6, argv=0x7fffffffdc88) at ../../src/emacs.c:2649
END BACKTRACE

VERSION INFO.
In GNU Emacs 31.0.50 (build 2, x86_64-pc-linux-gnu, X toolkit, cairo
 version 1.18.0, Xaw3d scroll bars) of 2024-12-09 built on maher
Repository revision: based off 1098ae2896f
Windowing system distributor 'The X.Org Foundation', version 11.0.12101014
System Description: Gentoo Linux

Configured using:
 'configure --with-x-toolkit=athena --with-native-compilation -C'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES NATIVE_COMP
NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3 THREADS TIFF
TOOLKIT_SCROLL_BARS TREE_SITTER WEBP X11 XAW3D XDBE XIM XINPUT2 XPM
LUCID ZLIB

Important settings:
  value of $LC_COLLATE: C
  value of $LANG: en_US.utf8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix
END VERSION INFO

bug#75120: 31.0.50; which-key crashes on xt if the scroll bar is activated.

[Eli Zaretskii]

> From: Madhu <enometh@meer.net>
> Date: Thu, 26 Dec 2024 20:56:01 +0530
> 
> Hello, Having heard about which-key mode I decided to try it.
> 
> gdb --args ../build-xt-native/src/emacs  -Q  -eval '(which-key-mode 1)' -eval '(setq window-min-height 8)'
> 
> 1. type C-x, wait 5 seconds, type C-g.
> 2. type C-x, wait 2 seconds for the 8 line frame with scrollbar, click the "up
> arrow" on the top of the scrollbar.

When I try this, Emacs signals an error, displaying "C-x
<vertical-scroll-bar> <mouse-1> is undefined" in the echo area.  But
I'm not on X.

Can someone else reproduce the crash?

bug#75120: 31.0.50; which-key crashes on xt if the scroll bar is activated.

[Robert Pluim]

>>>>> On Sat, 28 Dec 2024 14:10:35 +0200, Eli Zaretskii <eliz@gnu.org> said:

    >> From: Madhu <enometh@meer.net>
    >> Date: Thu, 26 Dec 2024 20:56:01 +0530
    >> 
    >> Hello, Having heard about which-key mode I decided to try it.
    >> 
    >> gdb --args ../build-xt-native/src/emacs  -Q  -eval '(which-key-mode 1)' -eval '(setq window-min-height 8)'
    >> 
    >> 1. type C-x, wait 5 seconds, type C-g.
    >> 2. type C-x, wait 2 seconds for the 8 line frame with scrollbar, click the "up
    >> arrow" on the top of the scrollbar.

    Eli> When I try this, Emacs signals an error, displaying "C-x
    Eli> <vertical-scroll-bar> <mouse-1> is undefined" in the echo area.  But
    Eli> I'm not on X.

    Eli> Can someone else reproduce the crash?

Yes. In xt_action_hook:

      x_send_scroll_bar_event (window_being_scrolled,
			       scroll_bar_end_scroll, 0, 0, false);
      w = XWINDOW (window_being_scrolled);
      bar = XSCROLL_BAR (w->vertical_scroll_bar); <-
			       w->vertical_scroll_bar == Qnil here

Although I have no clue what to do about it: I suspect the scrollbars
have been condemned by condemn_scroll_bars_hook, but then not
redeemed. Or maybe whatever is undoing or preventing the global
setting of "<vertical-scroll-bar> <mouse-1>" is responsible, but I
canʼt find where that is.

Robert
-- 

bug#75120: 31.0.50; which-key crashes on xt if the scroll bar is activated.

[Eli Zaretskii]

> From: Robert Pluim <rpluim@gmail.com>
> Cc: Madhu <enometh@meer.net>,  75120@debbugs.gnu.org
> Date: Wed, 08 Jan 2025 14:11:57 +0100
> 
> >>>>> On Sat, 28 Dec 2024 14:10:35 +0200, Eli Zaretskii <eliz@gnu.org> said:
> 
>     >> From: Madhu <enometh@meer.net>
>     >> Date: Thu, 26 Dec 2024 20:56:01 +0530
>     >> 
>     >> Hello, Having heard about which-key mode I decided to try it.
>     >> 
>     >> gdb --args ../build-xt-native/src/emacs  -Q  -eval '(which-key-mode 1)' -eval '(setq window-min-height 8)'
>     >> 
>     >> 1. type C-x, wait 5 seconds, type C-g.
>     >> 2. type C-x, wait 2 seconds for the 8 line frame with scrollbar, click the "up
>     >> arrow" on the top of the scrollbar.
> 
>     Eli> When I try this, Emacs signals an error, displaying "C-x
>     Eli> <vertical-scroll-bar> <mouse-1> is undefined" in the echo area.  But
>     Eli> I'm not on X.
> 
>     Eli> Can someone else reproduce the crash?
> 
> Yes. In xt_action_hook:
> 
>       x_send_scroll_bar_event (window_being_scrolled,
> 			       scroll_bar_end_scroll, 0, 0, false);
>       w = XWINDOW (window_being_scrolled);
>       bar = XSCROLL_BAR (w->vertical_scroll_bar); <-
> 			       w->vertical_scroll_bar == Qnil here
> 
> Although I have no clue what to do about it: I suspect the scrollbars
> have been condemned by condemn_scroll_bars_hook, but then not
> redeemed. Or maybe whatever is undoing or preventing the global
> setting of "<vertical-scroll-bar> <mouse-1>" is responsible, but I
> canʼt find where that is.

Maybe we should simply do what xt_horizontal_action_hook does for the
horizontal scroll bar, i.e. do nothing if w->vertical_scroll_bar is
nil?

Martin, WDYT?

bug#75120: 31.0.50; which-key crashes on xt if the scroll bar is activated.

[martin rudalics via Bug reports for GNU Emacs, the Swiss army knife of text editors]

 > Maybe we should simply do what xt_horizontal_action_hook does for the
 > horizontal scroll bar, i.e. do nothing if w->vertical_scroll_bar is
 > nil?

I checked in a trivial fix for this.  I'm not sure whether this will
leave some garbage behind - we probably should at least set
window_being_scrolled to nil if it is deleted (though how soon could it
be resurrected from a window configuration?) but I have no idea about
what to do with toolkit_scroll_bar_interaction.  These static variables
in xterm.c are some sort of a mess.

martin

bug#75120: 31.0.50; which-key crashes on xt if the scroll bar is activated.

[Robert Pluim]

>>>>> On Thu, 9 Jan 2025 09:52:24 +0100, martin rudalics <rudalics@gmx.at> said:

    >> Maybe we should simply do what xt_horizontal_action_hook does for the
    >> horizontal scroll bar, i.e. do nothing if w->vertical_scroll_bar is
    >> nil?

    martin> I checked in a trivial fix for this.  I'm not sure whether this will
    martin> leave some garbage behind - we probably should at least set
    martin> window_being_scrolled to nil if it is deleted (though how soon could it
    martin> be resurrected from a window configuration?) but I have no idea about
    martin> what to do with toolkit_scroll_bar_interaction.  These static variables
    martin> in xterm.c are some sort of a mess.

Thanks, I didnʼt realize the window was being deleted. Fixes it for me.

Robert
-- 

bug#75120: 31.0.50; which-key crashes on xt if the scroll bar is activated.

[martin rudalics via Bug reports for GNU Emacs, the Swiss army knife of text editors]

 >      martin> I checked in a trivial fix for this.  I'm not sure whether this will
 >      martin> leave some garbage behind - we probably should at least set
 >      martin> window_being_scrolled to nil if it is deleted (though how soon could it
 >      martin> be resurrected from a window configuration?) but I have no idea about
 >      martin> what to do with toolkit_scroll_bar_interaction.  These static variables
 >      martin> in xterm.c are some sort of a mess.
 >
 > Thanks, I didnʼt realize the window was being deleted. Fixes it for me.

If you have any ideas about the issues I mentioned above please tell me.

martin

bug#75120: 31.0.50; which-key crashes on xt if the scroll bar is activated.

[Robert Pluim]

>>>>> On Thu, 9 Jan 2025 10:35:49 +0100, martin rudalics <rudalics@gmx.at> said:

    martin> I checked in a trivial fix for this.  I'm not sure whether this will
    martin> leave some garbage behind - we probably should at least set
    martin> window_being_scrolled to nil if it is deleted (though how soon could it
    martin> be resurrected from a window configuration?) but I have no idea about
    martin> what to do with toolkit_scroll_bar_interaction.  These static variables
    martin> in xterm.c are some sort of a mess.
    >> 
    >> Thanks, I didnʼt realize the window was being deleted. Fixes it for me.

    martin> If you have any ideas about the issues I mentioned above please tell me.

I prefer not to look too hard at Xt related code 😀

Robert
--