Re: [PATCH] Fix crash with "maintenance print arc"

[Luis Machado <luis.machado@arm.com>]

On 4/29/22 11:18, Andrew Burgess wrote:
> Luis Machado via Gdb-patches <gdb-patches@sourceware.org> writes:
> 
>> On 4/28/22 16:26, Tom Tromey wrote:
>>>>>>>> "Luis" == Luis Machado via Gdb-patches <gdb-patches@sourceware.org> writes:
>>>
>>> Luis> While doing something else, I noticed GDB crashed with
>>> Luis> "maintenance print arc".
>>>
>>> I think the bug here is that this uses add_show_prefix_cmd and not
>>> add_basic_prefix_cmd.  See the appended, which also fixes the crash.
>>
>> Ah, you're right. It did look odd why we were feeding maint commands to
>> code that is supposed to handle show commands.
>>
>>>
>>> Luis> This happens because the code expects to find a "show" string pattern
>>> Luis> within "maintenance print arc", since "arc" here is a prefix, and skip it.
>>> Luis> In this case though, it won't find it, and we will have a bad pointer
>>> Luis> getting dereferenced.
>>>
>>> This looks reasonable to me.
>>
>> Should we prevent further situations like this by asserting that we
>> don't have a class_maintenance prefix being registered as a show
>> prefix?
> 
> Would this not trigger for all the existing 'maint show ...' commands?
> 

Ah, we have a "maint show" command. I wasn't aware of it until now.

Isn't this particular behavior a bit strange though? "maintenance" will 
always output the maintenance prefix, except for "maintenance show", 
which removes the show part.

It might be historical.