Re: [PATCH 1/2] Cygwin: stat(): Fix "Bad address" error on stat() for /dev/tty.

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

Hi Corinna,

On Fri, 7 Jul 2023 11:46:15 +0200
Corinna Vinschen wrote:
> On Jul  7 12:34, Takashi Yano wrote:
> > diff --git a/winsup/cygwin/dtable.cc b/winsup/cygwin/dtable.cc
> > index 18e0f3097..2aae2fd65 100644
> > --- a/winsup/cygwin/dtable.cc
> > +++ b/winsup/cygwin/dtable.cc
> > @@ -600,7 +600,13 @@ fh_alloc (path_conv& pc)
> >  	case FH_TTY:
> >  	  if (!pc.isopen ())
> >  	    {
> > -	      fhraw = cnew_no_ctor (fhandler_console, -1);
> > +	      if (CTTY_IS_VALID (myself->ctty))
> > +		{
> > +		  if (iscons_dev (myself->ctty))
> > +		    fhraw = cnew_no_ctor (fhandler_console, -1);
> > +		  else
> > +		    fhraw = cnew_no_ctor (fhandler_pty_slave, -1);
> > +		}
> 
> What happens if CTTY_IS_VALID fails at this point?  There's no
> `else' catching that situation?
> 
> >  	      debug_printf ("not called from open for /dev/tty");
> >  	    }
> >  	  else if (!CTTY_IS_VALID (myself->ctty) && last_tty_dev

That happens when CTTY is not assigned. In that case fhandler_nodevice
is assigned at:
https://cygwin.com/git/?p=newlib-cygwin.git;a=blob;f=winsup/cygwin/dtable.cc;h=18e0f3097823f00ff9651685be06583818eb2140;hb=e38f91d5a96c4554c69c833243e5afec8e3e90eb#l634

Then fhandler_base::fstat() is called when stat() is called.

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