Re: [PATCH][gdb/debuginfod] Ask to cancel further downloads

[Pedro Alves <pedro@palves.net>]

On 2022-09-29 8:29 p.m., Aaron Merey via Gdb-patches wrote:
> On Thu, Sep 29, 2022 at 4:34 AM Tom de Vries <tdevries@suse.de> wrote:
>> Add a new command "set debuginfod cancel one/all/ask", where:
>> - "one" means ^C cancels one download,
>> - "all" means ^C cancels all further downloads, and
>> - "ask" means ^C asks whether to cancel all further downloads.  A "yes" implies
>>   "set debuginfod cancel all", and a "no" implies "set debuginfod cancel one", so
>>   the question is only asked once.
>>
>> Note that the behaviour as it was before this patch is equivalent to
>> "set debuginfod cancel one".
>>
>> Instead, the new default is "set debuginfod cancel ask".
>>
>> Note that cancelling all further downloads implies "set debuginfod enabled off".
> 
> LGTM. It's a usability improvement and it worked as intended during testing.

Cool.  I think the thing missing (not in this patch, but in gdb) is handling
^C pressed while the inferior is running and GDB decides to download from debuginfod.

I mean, something like:

(gdb) c
...
# inferior is running, dlopens a library, and gdb downloads debug info from debuginfod

# just while gdb starts downloading one of the libraries, the user presses ^C, intending
# to pause the inferior.

I think gdb always switches to terminal-ours before downloading with debuginfod, and
assumes the ^C indicates the user wanted to cancel the download?

I think in this scenario, we should do something similar to target remote's "pressed twice"
handling.

- user presses once ctrl-c while download is happening _and_ inferior has terminal
    => Do nothing, set quit flag again, so ctrl-c isn't lost.  Set a global flag indicating
       ctrl-c was already pressed once.  The idea is that maybe the download finishes quickly,
       and then gdb soon elsewhere notices the quit_flag and stops the inferior.
       Everything Just Works.

- user is impacient and presses ctrl-c a second time while download is happening _and_
  inferior has terminal
    => gdb asks user what to do: 

       - interrupt program?
       - cancel download?

Pedro Alves