bug#5723: 23.1.94; make-network-process and emacs hangs

[YAMAMOTO Mitsuharu]

>>>>> On Thu, 18 Mar 2010 08:43:45 +0100, Helmut Eller <eller.helmut@gmail.com> 
>>>>> said:

> * YAMAMOTO Mitsuharu [2010-03-18 02:57+0100] writes:
>> If your case blocks at `connect', then it can't be quit with C-g
>> regardless of SYNC_INPUT on those ports/systems, because atimer is
>> turned off during the `connect' call.

> Why is the timer turned off around connect?  Handling SIGALARM
> during connect doesn't seem much different from handling SIGIO.

I think your argument makes sense.

I don't know the reason why the timer is turned off around connect.
The related code was added by the following change:

  committer: Ken Raeburn <raeburn@raeburn.org>
  timestamp: Sat 2000-06-24 06:06:53 +0000
  message:
    * process.c (Fopen_network_stream): Turn off atimers for duration of call to
    connect.  (Patch from Gerd.)

  
http://cvs.savannah.gnu.org/viewvc/emacs/src/process.c?root=emacs&r1=1.314&r2=1.315

And as of this change, SIGIO was also disabled.

25249 kwzh@gn |       /* Kernel bugs (on Ultrix at least) cause lossage (not 
just EINTR)
25249 kwzh@gn |          when connect is interrupted.  So let's not let it get 
interrupted.
25249 kwzh@gn |          Note we do not turn off polling, because polling is 
only used
25249 kwzh@gn |          when not interrupt_input, and thus not normally used 
on the systems
25249 kwzh@gn |          which have this bug.  On systems which use polling, 
there's no way
25249 kwzh@gn |          to quit if polling is turned off.  */
25249 kwzh@gn |       if (interrupt_input)
25249 kwzh@gn |         unrequest_sigio ();
25249 kwzh@gn | 
25249 kwzh@gn |       immediate_quit = 1;
25249 kwzh@gn |       QUIT;
25249 kwzh@gn | 
29922 raeburn |       /* This turns off all alarm-based interrupts; the
29922 raeburn |          bind_polling_period call above doesn't always turn all 
the
29922 raeburn |          short-interval ones off, especially if interrupt_input 
is
29922 raeburn |          set.
29922 raeburn | 
29922 raeburn |          It'd be nice to be able to control the connect timeout
29922 raeburn |          though.  Would non-blocking connect calls be portable? 
 */
29922 raeburn |       turn_on_atimers (0);
25249 kwzh@gn |       ret = connect (s, lres->ai_addr, lres->ai_addrlen);
29922 raeburn |       turn_on_atimers (1);

Does anyone have the mailing list archive around 2000-06?  It's not
found at list.gnu.org.

                                     YAMAMOTO Mitsuharu
                                mituharu@math.s.chiba-u.ac.jp