Re: [PATCH] t0005: skip signal death exit code test on Windows

[Johannes Sixt <j.sixt@viscovery.net>]

Am 6/7/2013 14:46, schrieb Erik Faye-Lund:
> On Fri, Jun 7, 2013 at 2:19 PM, Johannes Sixt <j.sixt@viscovery.net> wrote:
>> Am 6/7/2013 14:00, schrieb Erik Faye-Lund:
>>> On Fri, Jun 7, 2013 at 12:24 PM, Johannes Sixt <j.sixt@viscovery.net> wrote:
>>>> Am 6/7/2013 12:12, schrieb Erik Faye-Lund:
>>>>> diff --git a/compat/mingw.c b/compat/mingw.c
>>>>> index b295e2f..8b3c1b4 100644
>>>>> --- a/compat/mingw.c
>>>>> +++ b/compat/mingw.c
>>>>> @@ -1573,7 +1573,8 @@ static HANDLE timer_event;
>>>>>  static HANDLE timer_thread;
>>>>>  static int timer_interval;
>>>>>  static int one_shot;
>>>>> -static sig_handler_t timer_fn = SIG_DFL, sigint_fn = SIG_DFL;
>>>>> +static sig_handler_t timer_fn = SIG_DFL, sigint_fn = SIG_DFL,
>>>>> +    sigterm_fn = SIG_DFL;
>>>>>
>>>>>  /* The timer works like this:
>>>>>   * The thread, ticktack(), is a trivial routine that most of the time
>>>>> @@ -1688,6 +1689,10 @@ sig_handler_t mingw_signal(int sig,
>>>>> sig_handler_t handler)
>>>>>               sigint_fn = handler;
>>>>>               break;
>>>>>
>>>>> +     case SIGTERM:
>>>>> +             sigterm_fn = handler;
>>>>> +             break;
>>>>> +
>>>>>       default:
>>>>>               return signal(sig, handler);
>>>>>       }
>>>>> @@ -1715,6 +1720,13 @@ int mingw_raise(int sig)
>>>>>                       sigint_fn(SIGINT);
>>>>>               return 0;
>>>>>
>>>>> +     case SIGTERM:
>>>>> +             if (sigterm_fn == SIG_DFL)
>>>>> +                     exit(128 + SIGTERM);
>>>>> +             else if (sigterm_fn != SIG_IGN)
>>>>> +                     sigterm_fn(SIGTERM);
>>>>> +             return 0;
>>>>> +
>>>>>       default:
>>>>>               return raise(sig);
>>>>>       }
>>>>
>>>> That's pointless and does not work. The handler would only be called when
>>>> raise() is called, but not when a SIGTERM is received, e.g., via Ctrl-C
>>>> from the command line, because that route ends up in MSVCRT, which does
>>>> not know about this handler.
>>>
>>> That's not entirely true. On Windows, there's only *one* way to
>>> generate SIGTERM; "signal(SIGTERM)". Ctrl+C does not generate SIGTERM.
>>> We generate SIGINT on Ctrl+C in mingw_fgetc, but the default Control+C
>>> handler routine calls ExitProcess():
>>> http://msdn.microsoft.com/en-us/library/windows/desktop/ms683242(v=vs.85).aspx
>>
>> But a call to signal(SIGTERM, my_handler) should divert Ctrl+C to
>> my_handler. The unpatched version does, because MSVCRT now knows about
>> my_handler and sets things up so that the event handler calls my_handler.
> 
> No, it does not:
> Ctrl+C raises SIGINT, not SIGTERM.

<action type="slap" destination="forehead"/>

You are right. Your change would "fix" SIGTERM as it can be raised only
via raise() on Windows nor can it be caught when a process is killed via
mingw_kill(...,SIGTERM) by another process.

But then the current handling of SIGINT in compat/mingw.c is broken. The
handler is not propagated to MSVCRT, and after a SIGINT handler is
installed, Ctrl+C still terminates the process. No?

BTW, isn't mingw_signal() bogus in that it returns the SIGALRM handler
even if a SIGINT handler is installed?

-- Hannes