vifscreate() is used to create all virtual interfaces up-front and is
always called at the beginning of netstart, whether an explicit list of
interfaces is passed or none, i.e. all are to be configured.
Yet, to check the given interface exists, ifstart() uses ifcreate()
which obviously tries to create interfaces.
When ifstart() is run for every hostname.if(5) file, every virtual
interface is guaranteed to exist thanks to vifscreate().
Nonexistent physical interfaces with an existent config, e.g. urndis(4)
and cdce(4), will be skipped by ifstart() due to the failed ifcreate()
call, but not without ifcreate() trying the impossible:
$ ifconfig urndis0
urndis0: no such interface
# sh /etc/netstart -n urndis0
{ ifconfig urndis0 || ifconfig urndis0 create; }
ifconfig urndis0 inet6 autoconf
ifconfig urndis0 inet autoconf
This dry-run output does NOT match what netstart would really do:
# sh -x /etc/netstart urndis0 2>&1 | tail -n4
+ vifscreate urndis0
+ ifstart urndis0
+ defaultroute
+ return
Here, ifstart() runs but bails out on the failing ifcreate() call and
thus skips configuring urndis0 entirely.
So clarify the comment and replace the ifcreate() call with a simpler,
more obvious `ifconfig' check, which is exactly what ifcreate() boils
down to for existing interfaces:
# sh ./netstart -n urndis0 ; echo $?
0
Actual steps taken remain the same, i.e. none, as the new dry-run output
truthfully tells:
# sh -x ./netstart urndis0 2>&1 | tail -n4
+ vifscreate urndis0
+ ifstart urndis0
+ defaultroute
+ return
Virtual interfaces are now also created only once:
# sh /etc/netstart -n veb0
{ ifconfig veb0 || ifconfig veb0 create; }
{ ifconfig veb0 || ifconfig veb0 create; }
ifconfig veb0 description 'vmd(4) uplink'
ifconfig veb0 up
# sh ./netstart -n veb0
{ ifconfig veb0 || ifconfig veb0 create; }
ifconfig veb0 description 'vmd(4) uplink'
ifconfig veb0 up
Feedback? OK?
Index: netstart
===================================================================
RCS file: /cvs/src/etc/netstart,v
retrieving revision 1.227
diff -u -p -r1.227 netstart
--- netstart 1 Nov 2022 11:18:06 -0000 1.227
+++ netstart 1 Nov 2022 13:17:45 -0000
@@ -152,8 +152,8 @@ ifstart() {
chown -LR root:wheel $_hn
fi
- # Check for ifconfig'able interface, except if -n option is specified.
- ifcreate $_if || return
+ # Skip missing physical interface, virtual ones were created up front.
+ ifconfig $_if >/dev/null 2>&1 || return
# Parse the hostname.if(5) file and fill _cmds array with interface
# configuration commands.
