Re: Possiblly bug of cygwin1.dll

[Takashi Yano <takashi.yano@nifty.ne.jp>]

On Mon, 22 Jan 2024 10:57:48 +0100
Corinna Vinschen wrote:
> On Jan 22 10:25, Corinna Vinschen via Cygwin wrote:
> > On Jan 22 12:30, Takashi Yano via Cygwin wrote:
> > > PATCH2: (for cygwin)
> > > Avoid handle leak caused when non-static pthread_once_t is initialized
> > > with PTHREAD_ONCE_INIT
> > > diff --git a/winsup/cygwin/thread.cc b/winsup/cygwin/thread.cc
> > > index 7bb4f9fc8..127569160 100644
> > > --- a/winsup/cygwin/thread.cc
> > > +++ b/winsup/cygwin/thread.cc
> > > @@ -2060,6 +2060,9 @@ pthread::once (pthread_once_t *once_control, void (*init_routine) (void))
> > >      {
> > >        init_routine ();
> > >        once_control->state = 1;
> > > +      pthread_mutex_unlock (&once_control->mutex);
> > > +      while (pthread_mutex_destroy (&once_control->mutex) == EBUSY);
> > > +      return 0;
> > >      }
> > >    /* Here we must remove our cancellation handler */
> > >    pthread_mutex_unlock (&once_control->mutex);
> > 
> > I see what you're doing here.  Wouldn't it be simpler, though, to do this?
> > 
> > diff --git a/winsup/cygwin/thread.cc b/winsup/cygwin/thread.cc
> > index 7bb4f9fc8341..7ec3aace395d 100644
> > --- a/winsup/cygwin/thread.cc
> > +++ b/winsup/cygwin/thread.cc
> > @@ -2063,6 +2063,7 @@ pthread::once (pthread_once_t *once_control, void (*init_routine) (void))
> >      }
> >    /* Here we must remove our cancellation handler */
> 
> Strange enough, this comment accompanies the code since its inception
> in 2001.  It says explicitly "remove" the cancellation handler.
> That sounds like the idea was right, just the programmer forgot about
> it afterwards...

I am not sure what 'cancellation handler' means here. Is it the
event handler in pthread_mutex_t?

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