Date: Mon, 03 Jun 1996 15:51:27 +0000 From: Matt Thomas <matt@lkg.dec.com> To: Bruce Evans <bde@zeta.org.au> Cc: hackers@freebsd.org Subject: Re: PR conf/1270 Message-ID: <199606031551.PAA25025@whydos.lkg.dec.com> In-Reply-To: Your message of "Mon, 03 Jun 1996 08:33:50 %2B1000." <199606022233.IAA09273@godzilla.zeta.org.au>
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> There is a problem with dangling pointers. See kern_exit.c:
>
> /*
> * s_ttyp is not zero'd; we use this to indicate
> * that the session once had a controlling terminal.
> * (for logging and informational purposes)
> */
>
> and some things follow the pointer for closed devices. Perhaps only
> applications like ptstat -t. pstat also wants to work with an array of
> tty structs.
Digital UNIX had the same misfeature. Which is why it now uses
a vnode reference:
struct vnode *s_ttyvp; /* vnode of controlling terminal */
This also allows other things than classic ttys to be controlling
terminals (say streams devices or portals or ...).
> The same problems interfere with dynamic allocation of tty structs for
> hardware ttys, but there is less to be gained by dynamic allocation in
> this case. The closed tty structs are a good place for holding statstics
> and the state for the next open (they don't actually hold much of it now).
But that doesn't hold true for ptys.
--
Matt Thomas Internet: matt@3am-software.com
3am Software Foundry WWW URL: http://www.3am-software.com/bio/matt.html
Westford, MA Disclaimer: I disavow all knowledge of this message
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