Add support for hardwiring ppp sessions to particular devices with new

per-profile variables of the form ppp_<profile>_unit.  No ppp_unit
variable is supported since tying the same unit to more than one profile
won't work.

PR:		conf/122127
MFC after:	1 week

etc/rc.d/ppp

@@ -18,7 +18,7 @@ start_postcmd="ppp_poststart"
 
 ppp_start_profile()
 {
-	local _ppp_profile _ppp_mode _ppp_nat
+	local _ppp_profile _ppp_mode _ppp_nat _ppp_unit
 
 	_ppp_profile=$1
 	_ppp_profile_cleaned=$1
@@ -59,6 +59,13 @@ ppp_start_profile()
 		;;
 	esac
 
+	# Check for hard wired unit
+	eval _ppp_unit=\$ppp_${_ppp_profile_cleaned}_unit
+	if [ -n "_ppp_unit" ]; then
+		_ppp_unit="-unit${_ppp_unit}"
+	fi
+	rc_flags="$rc_flags $_ppp_unit"
+
 	# Run!
 	#
 	su -m $ppp_user -c "$command ${rc_flags} ${_ppp_profile}"

share/man/man5/rc.conf.5

@@ -1322,7 +1322,9 @@ The name of the profile to use from
 Also used for per-profile overrides of
 .Va ppp_mode
 and
-.Va ppp_nat .
+.Va ppp_nat ,
+and
+.Va ppp_ Ns Ao Ar profile Ac Ns _unit .
 When the profile name contains any of the characters
 .Dq Li .-/+
 they are translated to
@@ -1361,6 +1363,12 @@ Overrides the global
 .Va ppp_nat
 for
 .Ar profile .
+.It Va ppp_ Ns Ao Ar profile Ac Ns _unit
+.Pq Vt int
+Set the unit number to be used for this profile.
+See the manual description of
+.Fl unit Ns Ar N
+for details.
 .It Va ppp_user
 .Pq Vt str
 The name of the user under which