Re: [PATCH] stepi/nexti: skip signal handler if "handle nostop" signal arrives

Pedro Alves
2014-10-14T18:56:20Z

On 10/14/2014 07:49 PM, Pedro Alves wrote:
> On 10/14/2014 07:27 PM, Eli Zaretskii wrote:
>>> From: Pedro Alves <palves@redhat.com>
>>> Date: Tue, 14 Oct 2014 18:48:30 +0100
>>>
>>> --- a/gdb/doc/gdb.texinfo
>>> +++ b/gdb/doc/gdb.texinfo
>>> @@ -5526,6 +5526,11 @@ Their full names are:
>>> @value{GDBN} should not stop your program when this signal happens. It may
>>> still print a message telling you that the signal has come in.
>>>
>>> +If this signal arrives while a stepping command (e.g., @code{step}) is
>>> +in progress, the signal's handler is skipped (though still executed if
>>> +@code{pass} is in effect; see below). @value{GDBN} will still stop
>>> +your program if the handler hits a breakpoint.
>>
>> This description is confusing. For starters, it only mentions some of
>> the possible setting of signal handling, and keeps silence about the
>> rest. Either we should describe what happens with all of them, one by
>> one, or (better) says something that will explain how we handle them
>> all, at once.
>
> This paragraph is added to the "nostop" entry of the table. It directly
> relates to the entry in question:
>
> Specifically, it's a preemptive response to the question I'd have if
> I read the paragraph just above, which talks about the signal but
> leaves the question of the signal handler open:
>
> @table @code
> @item nostop
> @value{GDBN} should not stop your program when this signal happens. It may
> still print a message telling you that the signal has come in.
>
> If this signal arrives while a stepping command (e.g., @code{step}) is
> in progress, the signal's handler is skipped (though still executed if
> @code{pass} is in effect; see below). @value{GDBN} will still stop
> your program if the handler hits a breakpoint.
>
> I could extend the "stop" item:
>
> @item stop
> @value{GDBN} should stop your program when this signal happens. This implies
> the @code{print} keyword as well.
>
> Like:
>
> + The signal is not visible to the program until you continue.
>
> WDYT?
>
>
> This is also said further below, after the table (and is what the
> "see below" referred to):
>
> When a signal stops your program, the signal is not visible to the
> program until you
> continue. Your program sees the signal then, if @code{pass} is in
> effect for the signal in question @emph{at that time}. In other words,
> after @value{GDBN} reports a signal, you can use the @code{handle}
> command with @code{pass} or @code{nopass} to control whether your
> program sees that signal when you continue.
>
> +If a stepping command is issued after the program stops for a signal,
> +and @code{pass} is in effect for that signal, @value{GDBN} steps into
> +the signal's handler (if the target supports it).
>
> The '+' lines are what I'm adding.

Would this tweak below make it clearer? The contrast against stepping
mainline code is really the point I'm trying to make:

If a stepping command is issued after the program stops for a signal,
and @code{pass} is in effect for that signal, @value{GDBN} steps into
the signal's handler, instead of stepping the mainline code, if
the target supports it.

Thanks,
Pedro Alves