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Date: Thu, 9 Jun 2005 14:16:13 +0200 (CEST)
From: moreau francis <francis_moreau2000@yahoo.fr>
Subject: Re: [TTY] exclusive mode question
To: Frederik Deweerdt <dev.deweerdt@laposte.net>
Cc: Frederik Deweerdt <dev.deweerdt@laposte.net>, linux-kernel@vger.kernel.org
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--- Frederik Deweerdt <dev.deweerdt@laposte.net> a écrit :

> Le 09/06/05 11:59 +0200, moreau francis écrivit:
> > 
> > --- Frederik Deweerdt <dev.deweerdt@laposte.net> a écrit :
> > 
> > > I've just greped and I found :
> > > 
> > > if (!retval && test_bit(TTY_EXCLUSIVE, &tty->flags) &&
> > > !capable(CAP_SYS_ADMIN))
> > > 	retval = -EBUSY;
> > > in drivers/char/tty_io.c:tty_open
> > > 
> > > Which sources are you looking at?
> > > 
> > 
> > same source code but if another process has previously open the tty, how
> does
> > this source code detect it ?
> > 
> Sorry I misunderstood your question, there's no check on previous opens:
> from man tty_ioctl:
> 
>        TIOCEXCL  void
>               Put the tty into exclusive mode.  No _further_ open(2)
> operations  on  the  terminal  are  permitted.
>               (They will fail with EBUSY, except for root.)
> 

BTW, I don't see any use of this mode since it can't ensure that nothing is
using the tty...Do you know what kind of purpose it is for ?

               Francis


	
	
		
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