MFC r279571,281563 (allanjude):

Add a new safetly belt to freebsd-update to prevent a user doing a minor
update (-pX) while having an unfinished major upgrade (9.x to 9.y)
Safetly belt can be disabled with the -F flag

Additionally, add the --not-running-from-cron flag they bypasses the TTY
requirement, and allows freebsd-update to be invoked by orchestration
frameworks, scripts, or otherwise.

PR:		196760
Relnotes:	yes
Sponsored by:	ScaleEngine Inc.

usr.sbin/freebsd-update/freebsd-update.8

@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 14, 2010
+.Dd March 2, 2015
 .Dt FREEBSD-UPDATE 8
 .Os FreeBSD
 .Sh NAME
@@ -36,10 +36,12 @@
 .Op Fl b Ar basedir
 .Op Fl d Ar workdir
 .Op Fl f Ar conffile
+.Op Fl F
 .Op Fl k Ar KEY
 .Op Fl r Ar newrelease
 .Op Fl s Ar server
 .Op Fl t Ar address
+.Op Fl -not-running-from-cron
 .Cm command ...
 .Sh DESCRIPTION
 The
@@ -54,16 +56,16 @@ by the
 .Fx
 Release Engineering Team, e.g.,
 .Fx
-7.3-RELEASE and
+9.3-RELEASE and
 .Fx
-8.0-RELEASE, but not
+10.1-RELEASE, but not
 .Fx
-6.3-STABLE or
+9.3-STABLE or
 .Fx
-9.0-CURRENT.
+11-CURRENT.
 .Sh OPTIONS
 The following options are supported:
-.Bl -tag -width "-f conffile"
+.Bl -tag -width "-r newrelease"
 .It Fl b Ar basedir
 Operate on a system mounted at
 .Ar basedir .
@@ -81,6 +83,10 @@ Read configuration options from
 .Ar conffile .
 (default:
 .Pa /etc/freebsd-update.conf )
+.It Fl F
+Force
+.Nm Cm fetch
+to proceed where it normally would not, such as an unfinished upgrade
 .It Fl k Ar KEY
 Trust an RSA key with SHA256 of
 .Ar KEY .
@@ -98,12 +104,21 @@ Mail output of
 command, if any, to
 .Ar address .
 (default: root, or as given in the configuration file.)
+.It Fl -not-running-from-cron
+Force
+.Nm Cm fetch
+to proceed when there is no controlling tty.
+This is for use by automated scripts and orchestration tools.
+Please do not run
+.Nm Cm fetch
+from crontab or similar using this flag, see:
+.Nm Cm cron
 .El
 .Sh COMMANDS
 The
 .Cm command
 can be any one of the following:
-.Bl -tag -width "-f conffile"
+.Bl -tag -width "rollback"
 .It Cm fetch
 Based on the currently installed world and the configuration
 options set, fetch all available binary updates.

usr.sbin/freebsd-update/freebsd-update.sh

@@ -43,12 +43,15 @@ Options:
                   (default: /var/db/freebsd-update/)
   -f conffile  -- Read configuration options from conffile
                   (default: /etc/freebsd-update.conf)
+  -F           -- Force a fetch operation to proceed
   -k KEY       -- Trust an RSA key with SHA256 hash of KEY
   -r release   -- Target for upgrade (e.g., 6.2-RELEASE)
   -s server    -- Server from which to fetch updates
                   (default: update.FreeBSD.org)
   -t address   -- Mail output of cron command, if any, to address
                   (default: root)
+  --not-running-from-cron
+               -- Run without a tty, for use by automated tools
 Commands:
   fetch        -- Fetch updates from server
   cron         -- Sleep rand(3600) seconds, fetch updates, and send an
@@ -399,6 +402,12 @@ init_params () {
 
 	# No commands specified yet
 	COMMANDS=""
+
+	# Force fetch to proceed
+	FORCEFETCH=0
+
+	# Run without a TTY
+	NOTTYOK=0
 }
 
 # Parse the command line
@@ -411,6 +420,12 @@ parse_cmdline () {
 			if [ ! -z "${CONFFILE}" ]; then usage; fi
 			shift; CONFFILE="$1"
 			;;
+		-F)
+			FORCEFETCH=1
+			;;
+		--not-running-from-cron)
+			NOTTYOK=1
+			;;
 
 		# Configuration file equivalents
 		-b)
@@ -665,6 +680,14 @@ fetch_check_params () {
 		echo "(Did you mean 'upgrade' instead?)"
 		exit 1
 	fi
+
+	# Check that we have updates ready to install
+	if [ -f ${BDHASH}-install/kerneldone -a $FORCEFETCH -eq 0 ]; then
+		echo "You have a partially completed upgrade pending"
+		echo "Run '$0 install' first."
+		echo "Run '$0 fetch -F' to proceed anyway."
+		exit 1
+	fi
 }
 
 # Perform sanity checks etc. before fetching upgrades.
@@ -3202,7 +3225,7 @@ get_params () {
 # Fetch command.  Make sure that we're being called
 # interactively, then run fetch_check_params and fetch_run
 cmd_fetch () {
-	if [ ! -t 0 ]; then
+	if [ ! -t 0 -a $NOTTYOK -eq 0 ]; then
 		echo -n "`basename $0` fetch should not "
 		echo "be run non-interactively."
 		echo "Run `basename $0` cron instead."