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Date: Mon, 6 Mar 1995 11:13:22 +1000
From: Bruce Evans <bde@zeta.org.au>
Message-Id: <199503060113.LAA08845@godzilla.zeta.org.au>
To: current@FreeBSD.org, gibbs@estienne.CS.Berkeley.EDU
Subject: Re: Unprotected area of termios.h?
Sender: current-owner@FreeBSD.org
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>Why was this done?

>/*
> * END OF PROTECTED INCLUDE.
> */
>#endif /* !_SYS_TERMIOS_H_ */

>#ifndef _POSIX_SOURCE
>#include <sys/ttydefaults.h>
>#endif

It's a hack for some programs wanting to get the definition of
ttydefchars[] by including a header twice with TTYDEFCHARS
defined the second time, and expecting to get this definition
as namespace pollution in <[sys/]termios.h> instead of from
<sys/ttydefaults.h>.

The new ld has apparently uncovered the bug that sio.c and tty.c
both define ttydefchars[] as globals.  This was fixed in 1.1.5
by making ttydefchars[] static like it should always have been.
See the revision log for the 2.0 <sys/ttydefaults.h> for how
the non-idempotency hack was broken and the revision log for the
1.1.5 <sys/ttydefaults.h> for ancient history.

Bruce