svn commit: r194538 - head/sys/sys

[David Schultz]

On Sat, Jun 20, 2009, Kostik Belousov wrote:
> On Sat, Jun 20, 2009 at 04:39:25PM +0000, Ed Schouten wrote:
> > Author: ed
> > Date: Sat Jun 20 16:39:25 2009
> > New Revision: 194538
> > URL: http://svn.freebsd.org/changeset/base/194538
> > 
> > Log:
> >   Add placeholder to prevent reuse of privilege 254.
> >   
> >   Requested by:	rwatson
> > 
> > Modified:
> >   head/sys/sys/priv.h
> > 
> > Modified: head/sys/sys/priv.h
> > ==============================================================================
> > --- head/sys/sys/priv.h	Sat Jun 20 16:37:24 2009	(r194537)
> > +++ head/sys/sys/priv.h	Sat Jun 20 16:39:25 2009	(r194538)
> > @@ -211,6 +211,7 @@
> >  #define	PRIV_TTY_DRAINWAIT	251	/* Set tty drain wait time. */
> >  #define	PRIV_TTY_DTRWAIT	252	/* Set DTR wait on tty. */
> >  #define	PRIV_TTY_EXCLUSIVE	253	/* Override tty exclusive flag. */
> > +#define	_PRIV_TTY_PRISON	254	/* Removed. */
> >  #define	PRIV_TTY_STI		255	/* Simulate input on another tty. */
> >  #define	PRIV_TTY_SETA		256	/* Set tty termios structure. */
> >  
> Names starting with two underscores or underscore and upper-case letter
> are reserved to the C language implementation. We should not use it
> in the code.

Applications are not supposed to use such symbols, but we use them
pervasively in system headers specifically to avoid conflicting
with symbols an application might define.  (Effectively, we
consider system headers to be part of the language implementation.)