rc: Improve load_kld

* Centralize the usage message.

* Document and enforce that -e and -m are mutually exclusive; previously,
  speficying both would result in only -e being applied.

* If -e was not specified, and -m was not specified or did not match,
  fall back to `kldstat -n file` which will always work for modules that
  aren't built into the kernel.

This means the kld and ntpd scripts can now rely on load_kld to dtrt.

MFC after:	1 week
Reviewed by:	imp
Differential Revision:	https://reviews.freebsd.org/D57706

3 files changed, 19 insertions, 16 deletions

diff --git a/libexec/rc/rc.d/kld b/libexec/rc/rc.d/kld
index d18ba2f08346..851db5dd6a32 100755
--- a/libexec/rc/rc.d/kld
+++ b/libexec/rc/rc.d/kld
@@ -44,10 +44,12 @@ kld_start()
 
 	local _kld
 
-	startmsg "Loading kernel modules: ${kld_list}"
+	startmsg -n "Loading kernel modules:"
 	for _kld in $kld_list ; do
-		load_kld -e ${_kld}.ko $_kld
+		load_kld $_kld
+		startmsg -n " ${_kld}"
 	done
+	startmsg "."
 }
 
 load_rc_config $name
diff --git a/libexec/rc/rc.d/ntpd b/libexec/rc/rc.d/ntpd
index e7e42da8acc7..a46a32144cce 100755
--- a/libexec/rc/rc.d/ntpd
+++ b/libexec/rc/rc.d/ntpd
@@ -67,7 +67,7 @@ can_run_nonroot()
 	# the policy module if not already present, then check whether the
 	# policy has been disabled via tunable or sysctl.
 	[ -n "$(sysctl -qn security.mac.version)" ] || return 1
-	sysctl -qn security.mac.ntpd >/dev/null || kldload -qn mac_ntpd || return 1
+	load_kld mac_ntpd || return 1
 	[ "$(sysctl -qn security.mac.ntpd.enabled)" == "1" ] || return 1
 
 	# On older existing systems, the ntp dir may by owned by root, change
diff --git a/libexec/rc/rc.subr b/libexec/rc/rc.subr
index 101c69e93cde..7cb652e5ec17 100644
--- a/libexec/rc/rc.subr
+++ b/libexec/rc/rc.subr
@@ -2423,37 +2423,38 @@ mount_md()
 
 # Code common to scripts that need to load a kernel module
 # if it isn't in the kernel yet. Syntax:
-#   load_kld [-e regex] [-m module] file
+#   load_kld [-e regex | -m module] file
 # where -e or -m chooses the way to check if the module
 # is already loaded:
-#   regex is egrep'd in the output from `kldstat -v',
-#   module is passed to `kldstat -m'.
-# The default way is as though `-m file' were specified.
+#   -e greps the output from `kldstat -v',
+#   -m uses `kldstat -m module'.
+# The default way is as though `-m file` was specified.
 load_kld()
 {
-	local _loaded _mod _opt _re
+	local _loaded _mod _opt _re _x
 
+	_x=0
 	while getopts "e:m:" _opt; do
 		case "$_opt" in
 		e) _re="$OPTARG" ;;
 		m) _mod="$OPTARG" ;;
-		*) err 3 'USAGE: load_kld [-e regex] [-m module] file' ;;
+		*) _x=999 ;;
 		esac
+		_x=$((_x + 1))
 	done
 	shift $(($OPTIND - 1))
-	if [ $# -ne 1 ]; then
-		err 3 'USAGE: load_kld [-e regex] [-m module] file'
+	if [ $# -ne 1 ] || [ $_x -gt 1 ]; then
+		err 3 'USAGE: load_kld [-e regex | -m module] file'
 	fi
-	_mod=${_mod:-$1}
 	_loaded=false
 	if [ -n "$_re" ]; then
 		if kldstat -v | egrep -q -e "$_re"; then
 			_loaded=true
 		fi
-	else
-		if kldstat -q -m "$_mod"; then
-			_loaded=true
-		fi
+	elif kldstat -q -m "${_mod:-$1}"; then
+		_loaded=true
+	elif kldstat -q -n "$1"; then
+		_loaded=true
 	fi
 	if ! $_loaded; then
 		if ! kldload "$1"; then