Another pipe-related problem?

[Takashi Yano]

On Wed, 10 Nov 2021 08:29:32 +0900
Takashi Yano wrote:
> On Wed, 10 Nov 2021 08:22:45 +0900
> Takashi Yano wrote:
> > On Tue, 9 Nov 2021 09:11:28 -0500
> > Ken Brown wrote:
> > > I'll have to reproduce the hang myself in order to test this (or maybe you could 
> > > test it), but I now have a new guess: If the read call above keeps failing with 
> > > EINTR, then we're in an infinite loop.  This could happen because of the 
> > > following code in fhandler_pipe::raw_read:
> > > 
> > >    DWORD waitret = cygwait (read_mtx, timeout);
> > >    switch (waitret)
> > >      {
> > >      case WAIT_OBJECT_0:
> > >        break;
> > >      case WAIT_TIMEOUT:
> > >        set_errno (EAGAIN);
> > >        len = (size_t) -1;
> > >        return;
> > >      default:
> > >        set_errno (EINTR);
> > >        len = (size_t) -1;
> > >        return;
> > >      }
> > > 
> > > Takashi, is EINTR really the appropriate errno in the default case?  Isn't 
> > > cygwait supposed to handle signals?
> > 
> > I assume cygwait() returns WAIT_SIGNALED when signalled
> > by SIGINT, SIGTERM, SIGTSTP, etc...  In this case, EINTR
> > should return I think.
> > 
> > Is it wrong?
> 
> Ah, if SA_RESTART is set, we should continue to read even
> if signalled...

So, should this be like following?

 restart_wait_read_mtx:
   DWORD waitret = cygwait (read_mtx, timeout, cw_sig_eintr);
   switch (waitret)
     {
     case WAIT_OBJECT_0:
       break;
     case WAIT_TIMEOUT:
       set_errno (EAGAIN);
       len = (size_t) -1;
       return;
     case WAIT_SIGNALED:
       if (_my_tls.call_signal_handler ())
         goto restart_wait_read_mtx;
       set_errno (EINTR);
       len = (size_t) -1;
       return;
     default:
       /* Should not reach here. */
       __seterrno ();
       len = (size_t) -1;
       return;
     }

-- 
Takashi Yano <takashi.yano@nifty.ne.jp>