bug#34394: 27.0.50; Emacs segfaults with SLY, company and C-g

[João Távora]

Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Sat, 09 Feb 2019 14:11:36 +0200
>> From: Eli Zaretskii <eliz@gnu.org>
>> Cc: 34394@debbugs.gnu.org, schwab@linux-m68k.org
>> 
>> Type "up" until you get into a call-stack frame in our sources, which
>> should be this:
>> Then just "p Vquit_flag" should do.  Yes, it is a global.
>
> More accurately, it's a macro that expands to a global.  If just
> typing "p Vquit_flag" doesn't work, try "p globals.f_Vquit_flag".

Oh right.  That was needed ('up' isn't needed and I was already in frame
8 anyway).

Anyway it's XIL(0xc750)

    (gdb) p globals.f_Vquit_flag 
    $1 = XIL(0xc750)

Backtrace attached.

João


gdb --args ./emacs -Q -L ~/Source/Emacs/sly -l sly-autoloads -L 
~/Source/Emacs/company-mode -l ~/Source/Emacs/company-mode/company.el -f 
global-company-mode -f sly
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Reading symbols from ./emacs...done.
SIGINT is used by the debugger.
Are you sure you want to change it? (y or n) [answered Y; input not from 
terminal]
DISPLAY = :0
TERM = xterm
Breakpoint 1 at 0x15015c: file emacs.c, line 370.
Temporary breakpoint 2 at 0x172efd: file lisp.h, line 1056.
(gdb) r
Starting program: /home/capitaomorte/Source/Emacs/emacs-master/src/emacs -Q -L 
/home/capitaomorte/Source/Emacs/sly -l sly-autoloads -L 
/home/capitaomorte/Source/Emacs/company-mode -l 
/home/capitaomorte/Source/Emacs/company-mode/company.el -f global-company-mode 
-f sly
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Detaching after vfork from child process 16838]
[Detaching after vfork from child process 16846]
[Detaching after vfork from child process 16847]
*** longjmp causes uninitialized stack frame ***: 
/home/capitaomorte/Source/Emacs/emacs-master/src/emacs terminated

Program received signal SIGABRT, Aborted.
__GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
50      ../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) where
#0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
#1  0x00007ffff4f6d535 in __GI_abort () at abort.c:79
#2  0x00007ffff4fc4718 in __libc_message (action=<optimized out>, 
fmt=fmt@entry=0x7ffff50cf088 "*** %s ***: %s terminated\n") at 
../sysdeps/posix/libc_fatal.c:181
#3  0x00007ffff5055bbd in __GI___fortify_fail_abort 
(need_backtrace=need_backtrace@entry=true, 
    msg=0x7ffff50cf03d <longjmp_msg> "longjmp causes uninitialized stack 
frame") at fortify_fail.c:28
#4  0x00007ffff5055bf1 in __GI___fortify_fail (msg=<optimized out>) at 
fortify_fail.c:44
#5  0x00007ffff5055aad in ____longjmp_chk () at 
../sysdeps/unix/sysv/linux/x86_64/____longjmp_chk.S:105
#6  0x00007ffff5055a0b in __longjmp_chk (env=0x555555d01238 <main_thread+216>, 
val=val@entry=1) at ../setjmp/longjmp.c:39
#7  0x00005555556b22d4 in quit_throw_to_read_char 
(from_signal=from_signal@entry=false) at keyboard.c:10486
#8  0x00005555556ba3cd in set_waiting_for_input 
(time_to_clear=time_to_clear@entry=0x7fffffffd130) at keyboard.c:10253
#9  0x000055555579007c in wait_reading_process_output 
(time_limit=time_limit@entry=30, nsecs=nsecs@entry=0, read_kbd=-1, 
do_display=do_display@entry=true, 
    wait_for_cell=..., wait_proc=wait_proc@entry=0x0, just_wait_proc=0) at 
process.c:5212
#10 0x00005555555983ac in sit_for (timeout=..., timeout@entry=make_number(30), 
reading=reading@entry=true, display_option=display_option@entry=1) at 
lisp.h:1056
#11 0x00005555556b6209 in read_char (commandflag=1, map=..., 
map@entry=XIL(0x555556b12603), prev_event=XIL(0), 
used_mouse_menu=used_mouse_menu@entry=0x7fffffffd5cb, 
    end_time=end_time@entry=0x0) at lisp.h:751
#12 0x00005555556b74f5 in read_key_sequence 
(keybuf=keybuf@entry=0x7fffffffd690, prompt=XIL(0x555555d68c90), 
dont_downcase_last=dont_downcase_last@entry=false, 
    can_return_switch_frame=can_return_switch_frame@entry=true, 
fix_current_buffer=fix_current_buffer@entry=true, 
prevent_redisplay=prevent_redisplay@entry=false)
    at keyboard.c:9082
#13 0x00005555556b8bc1 in command_loop_1 () at lisp.h:1056
#14 0x0000555555741a96 in internal_condition_case 
(bfun=bfun@entry=0x5555556b8943 <command_loop_1>, handlers=..., 
handlers@entry=XIL(0x55b0), 
    hfun=hfun@entry=0x5555556acf6d <cmd_error>) at eval.c:1376
#15 0x00005555556a9494 in command_loop_2 (ignore=..., ignore@entry=XIL(0)) at 
lisp.h:1056
#16 0x00005555557419da in internal_catch (tag=..., 
func=func@entry=0x5555556a9478 <command_loop_2>, arg=..., arg@entry=XIL(0)) at 
eval.c:1139
#17 0x00005555556a6786 in command_loop () at lisp.h:1056
#18 0x00005555556ac728 in recursive_edit_1 () at keyboard.c:714
#19 0x00005555556accf0 in Frecursive_edit () at keyboard.c:785
#20 0x00005555556a5154 in main (argc=14, argv=<optimized out>) at emacs.c:1949
(gdb) frame 7
#7  0x00005555556b22d4 in quit_throw_to_read_char 
(from_signal=from_signal@entry=false) at keyboard.c:10486
10486     sys_longjmp (getcjmp, 1);
(gdb) p Vquit_flag
No symbol "Vquit_flag" in current context.
(gdb) p glob
glob                   glob64-lstat-compat.c  glob@GLIBC_2.2.5       
glob_pattern_p         globalNamespace        globals                
globfree64.c
glob-lstat-compat.c    glob64.c               glob@got.plt           
glob_pattern_p.c       global_code            globals.h              
globfree@got.plt
glob.c                 glob64@@GLIBC_2.27     glob@plt               glob_t     
            global_lock            globfree               globfree@plt
glob.h                 glob64@GLIBC_2.2.5     glob_in_dir            global     
            global_map             globfree.c             
glob64                 glob@@GLIBC_2.27       glob_internal.h        
global-locale.c        global_max_fast        globfree64             
(gdb) p global
global           global-locale.c  globalNamespace  global_code      global_lock 
     global_map       global_max_fast  globals          globals.h
(gdb) p globals.f_Vquit_flag 
$1 = XIL(0xc750)
(gdb) p *globals.f_Vquit_flag 
Structure has no component named operator*.
(gdb)