gdb "command" broken with -mi

gdb "command" broken with -mi

[Ryan Johnson]

Hi all,

I noticed during a recent debug session that gdb's "command" command 
(setting actions to perform when a breakpoint triggers) doesn't work. 
You can start to enter the list of commands, but emacs ignores the "end" 
keyword that should terminate the list, forcing you to cancel the 
attempt with C-c C-c.

Is this a known issue?

Thanks,
Ryan

Re: gdb "command" broken with -mi

[Eli Zaretskii]

> Date: Tue, 20 Aug 2013 08:55:54 -0400
> From: Ryan Johnson <ryan.johnson@cs.utoronto.ca>
> 
> I noticed during a recent debug session that gdb's "command" command 
> (setting actions to perform when a breakpoint triggers) doesn't work. 
> You can start to enter the list of commands, but emacs ignores the "end" 
> keyword that should terminate the list, forcing you to cancel the 
> attempt with C-c C-c.
> 
> Is this a known issue?

This used to be a problem in older versions of Emacs, but it was fixed
more than a year ago, and all versions of Emacs from 24.3 (inclusive)
onwards should not fail this way.  What version of Emacs are you
using?

FWIW, I've just tried this in yesterday's trunk, and it works for me
in a simple test case.

Re: gdb "command" broken with -mi

[Ryan Johnson]

On 20/08/2013 10:35 AM, Eli Zaretskii wrote:
>> Date: Tue, 20 Aug 2013 08:55:54 -0400
>> From: Ryan Johnson <ryan.johnson@cs.utoronto.ca>
>>
>> I noticed during a recent debug session that gdb's "command" command
>> (setting actions to perform when a breakpoint triggers) doesn't work.
>> You can start to enter the list of commands, but emacs ignores the "end"
>> keyword that should terminate the list, forcing you to cancel the
>> attempt with C-c C-c.
>>
>> Is this a known issue?
> This used to be a problem in older versions of Emacs, but it was fixed
> more than a year ago, and all versions of Emacs from 24.3 (inclusive)
> onwards should not fail this way.  What version of Emacs are you
> using?
>
> FWIW, I've just tried this in yesterday's trunk, and it works for me
> in a simple test case.
I'm using 24.3.2 with Ken's cygwin patches.

The STC is:
1. gcc -g -ostc -xc <(echo "int main() { return 0; }")
2. Fire up emacs M-x gdb and point it at stc
3. b main
4. comm 1
> Reading symbols from /home/Ryan/experiments/a.exe...done.
> (gdb) b main
> Breakpoint 1 at 0x1004010dd: file stc.c, line 2.
> (gdb) comm 1
> Type commands for breakpoint(s) 1, one per line.
> End with a line saying just "end".
> >p $pc
> >end
> >
> >
> >  C-c C-cQuit
> (gdb)

If it's fixed in later versions, though, maybe Ken's (hopefully 
soon-arriving) cygwin package update that fixes the stack overflow 
problem will also pick up this fix.

Thanks,
Ryan

Re: gdb "command" broken with -mi

[Liang Wang]

[-- Attachment #1: Type: text/plain, Size: 1647 bytes --]

On Aug 20, 2013 8:04 AM, "Ryan Johnson" <ryan.johnson@cs.utoronto.ca> wrote:
>
> On 20/08/2013 10:35 AM, Eli Zaretskii wrote:
>>>
>>> Date: Tue, 20 Aug 2013 08:55:54 -0400
>>> From: Ryan Johnson <ryan.johnson@cs.utoronto.ca>
>>>
>>> I noticed during a recent debug session that gdb's "command" command
>>> (setting actions to perform when a breakpoint triggers) doesn't work.
>>> You can start to enter the list of commands, but emacs ignores the "end"
>>> keyword that should terminate the list, forcing you to cancel the
>>> attempt with C-c C-c.
>>>
>>> Is this a known issue?
>>
>> This used to be a problem in older versions of Emacs, but it was fixed
>> more than a year ago, and all versions of Emacs from 24.3 (inclusive)
>> onwards should not fail this way.  What version of Emacs are you
>> using?
>>
>> FWIW, I've just tried this in yesterday's trunk, and it works for me
>> in a simple test case.
>
> I'm using 24.3.2 with Ken's cygwin patches.
>
> The STC is:
> 1. gcc -g -ostc -xc <(echo "int main() { return 0; }")
> 2. Fire up emacs M-x gdb and point it at stc
> 3. b main
> 4. comm 1
>>
>> Reading symbols from /home/Ryan/experiments/a.exe...done.
>> (gdb) b main
>> Breakpoint 1 at 0x1004010dd: file stc.c, line 2.
>> (gdb) comm 1

I'm afraid that you have to type "commands" exactly.

>> Type commands for breakpoint(s) 1, one per line.
>> End with a line saying just "end".
>> >p $pc
>> >end
>> >
>> >
>> >  C-c C-cQuit
>> (gdb)
>
>
> If it's fixed in later versions, though, maybe Ken's (hopefully
soon-arriving) cygwin package update that fixes the stack overflow problem
will also pick up this fix.
>
> Thanks,
> Ryan
>
>
>

[-- Attachment #2: Type: text/html, Size: 2469 bytes --]

Re: gdb "command" broken with -mi

[Eli Zaretskii]

> Date: Tue, 20 Aug 2013 08:38:13 -0700
> From: Liang Wang <netcasper@gmail.com>
> Cc: Eli Zaretskii <eliz@gnu.org>, emacs-devel@gnu.org
> 
> >> Breakpoint 1 at 0x1004010dd: file stc.c, line 2.
> >> (gdb) comm 1
> 
> I'm afraid that you have to type "commands" exactly.

Ah, yes, I remember now.  (I always type "com TAB", so completion does
that for me.)  You can hack gdb-control-commands-regexp to include
abbreviations as well.

Re: gdb "command" broken with -mi

[Ryan Johnson]

On 20/08/2013 11:54 AM, Eli Zaretskii wrote:
>> Date: Tue, 20 Aug 2013 08:38:13 -0700
>> From: Liang Wang <netcasper@gmail.com>
>> Cc: Eli Zaretskii <eliz@gnu.org>, emacs-devel@gnu.org
>>
>>>> Breakpoint 1 at 0x1004010dd: file stc.c, line 2.
>>>> (gdb) comm 1
>> I'm afraid that you have to type "commands" exactly.
> Ah, yes, I remember now.  (I always type "com TAB", so completion does
> that for me.)  You can hack gdb-control-commands-regexp to include
> abbreviations as well.
Ah! I have to type "comm [TAB]" because otherwise there are three 
completions to choose from, but it does work.

Thanks,
Ryan

Re: gdb "command" broken with -mi

[Eli Zaretskii]

> Date: Tue, 20 Aug 2013 11:03:51 -0400
> From: Ryan Johnson <ryan.johnson@cs.utoronto.ca>
> CC: emacs-devel@gnu.org
> 
> The STC is:
> 1. gcc -g -ostc -xc <(echo "int main() { return 0; }")
> 2. Fire up emacs M-x gdb and point it at stc
> 3. b main
> 4. comm 1
> > Reading symbols from /home/Ryan/experiments/a.exe...done.
> > (gdb) b main
> > Breakpoint 1 at 0x1004010dd: file stc.c, line 2.
> > (gdb) comm 1
> > Type commands for breakpoint(s) 1, one per line.
> > End with a line saying just "end".
> > >p $pc
> > >end
> > >
> > >
> > >  C-c C-cQuit
> > (gdb)
> 
> If it's fixed in later versions, though, maybe Ken's (hopefully 
> soon-arriving) cygwin package update that fixes the stack overflow 
> problem will also pick up this fix.

v24.3 should have the fix.  This works for me on Windows (in a native
build) and on GNU/Linux, so this could be something specific to Cygwin
or to your system.

Some things to try:

  . Once you enter GDB, type "set interactive-mode off" before any
    other GDB command, and see if that solves the problem.

  . Try a different version of GDB, especially if you are using some
    development snapshot.

  . Make sure your gdb-mi.el has a variable named gdb-control-level
    (this was part of solving the problem).  Also, make sure you don't
    have some old gdb-mi.el shadowing the one in v24.3.