Add support for processing add-on modules from /usr/local/libexec/bsdconfig

(this is designed to allow new modules to be installed via ports/packages).

To prevent conflict with itself (sysutils/bsdconfig) as a port (which
installs its base modules to the above directory, it was long-ago decided
that so-called `base' modules would look different than now-defined `add-on'
modules. The structure of the contents for each is the same, but the naming
convention for the module directory must be different.

Base modules are named `[0-9][0-9][0-9].*' to allow SysV-style organization
while add-on modules must avoid this naming style and are simply listed in
alphabetical order by their module directory.

For example, a hypothetical port named `bsdconfig-jails' could install
/usr/local/libexec/bsdconfig/jails and provide `bsdconfig jails' as well as
a new menu entry in the main-menu.

Add-on modules are listed in the main-menu (when bsdconfig is executed with-
out arguments) below a separator after the last base-module.

In `bsdconfig -h' output, add-on modules are listed right alongside base
modules (sorted alphabetically in columnar fashion; left-to-right).

If a base module declares a keyword used by an add-on module, the base
module will always win when given `bsdconfig keyword' syntax.

Add-on modules should avoid declaring any keyword found in `script.subr' as
a reserved-word (`Resword') since bsdconfig also supports `bsdconfig resword'
as a fall-back if no keyword is found to be declared by any module.

usr.sbin/bsdconfig/bsdconfig

@@ -57,6 +57,13 @@ f_include_lang $BSDCFG_LIBE/include/messages.subr
 BSDCONFIG_HELPFILE=$BSDCFG_LIBE/include/bsdconfig.hlp
 USAGE_HELPFILE=$BSDCFG_LIBE/include/usage.hlp
 
+############################################################ CONFIGURATION
+
+#
+# Alternate `local' libexec directory for add-on modules (e.g., from ports)
+#
+BSDCFG_LOCAL_LIBE="/usr/local/libexec/bsdconfig"
+
 ############################################################ FUNCTIONS
 
 # usage
@@ -83,6 +90,27 @@ usage()
 		}' */$index | sort
 	)
 
+	local alt_cmd_list # Calculated below (if $BSDCFG_LOCAL_LIBE exists)
+	if f_quietly cd $BSDCFG_LOCAL_LIBE; then
+		# No need to preserve CWD (headed toward exit)
+
+		# Test for language-specific indices
+		f_quietly ls */"$index.${LANG:-$LC_ALL}" &&
+			index="$index.${LANG:-$LC_ALL}"
+
+		alt_cmd_list=$(
+			awk '/^menu_selection="/ {
+				sub(/\|.*/, "")
+				sub(/^menu_selection="/, "")
+				print
+			}' */$index 2> /dev/null | sort
+		)
+
+		# Conflate lists, removing duplicates
+		cmd_list=$( printf "%s\n%s\n" \
+		                   "$cmd_list" "$alt_cmd_list" | sort -u )
+	fi
+
 	#
 	# Determine the longest command-length (in characters)
 	#
@@ -167,6 +195,9 @@ dialog_menu_main()
 	local defaultitem= # Calculated below
 	local hline=
 
+	#
+	# Pick up the base modules (directories named `[0-9][0-9][0-9].*')
+	#
 	local menuitem menu_title menu_help menu_selection index=2
 	for menuitem in $( cd $BSDCFG_LIBE && ls -d [0-9][0-9][0-9].* ); do
 		[ $index -lt ${#DIALOG_MENU_TAGS} ] || break
@@ -190,6 +221,49 @@ dialog_menu_main()
 		index=$(( $index + 1 ))
 	done
 
+	#
+	# Process the `local' libexec sources.
+	#
+	# Whereas modules in $BSDCFG_LIBE must be named [0-9][0-9][0-9].*
+	# modules in $BSDCFG_LOCAL_LIBE should NOT be named this way (making it
+	# more practical for port-maintainers).
+	#
+	# This also has the fortunate side-effect of making the de-duplication
+	# effort rather simple (because so-called `base' modules must be named
+	# differently than add-on modules).
+	#
+	local separator_added=
+	for menuitem in $( cd "$BSDCFG_LOCAL_LIBE" 2> /dev/null && ls -d * )
+	do
+		[ $index -lt ${#DIALOG_MENU_TAGS} ] || break
+
+		# Skip the module if it looks like a `base' module
+		case "$menuitem" in [0-9][0-9][0-9].*) continue;; esac
+
+		menu_program= menu_title= menu_help=
+		f_include_lang $BSDCFG_LOCAL_LIBE/$menuitem/INDEX || continue
+		[ "$menu_program" ] || continue
+
+		if [ ! "$separator_added" ]; then
+			menu_list="$menu_list '-' '-' ''"
+			separator_added=1
+		fi
+
+		case "$menu_program" in
+		/*) : already fully qualified ;;
+		 *) menu_program="$BSDCFG_LOCAL_LIBE/$menuitem/$menu_program"
+		esac
+
+		tag=$( f_substr "$DIALOG_MENU_TAGS" $index 1 )
+		setvar "menu_program$tag" "$menu_program"
+
+		f_shell_escape "$menu_title" menu_title
+		f_shell_escape "$menu_help" menu_help
+		menu_list="$menu_list '$tag' '$menu_title' '$menu_help'"
+
+		index=$(( $index + 1 ))
+	done
+
 	local height width rows
 	eval f_dialog_menu_with_help_size height width rows \
 	                                  \"\$title\"  \

usr.sbin/bsdconfig/share/common.subr

@@ -531,12 +531,22 @@ f_index_file()
 
 	if [ "$lang" ]; then
 		awk -v keyword="$keyword" "$f_index_file_awk" \
-			$BSDCFG_LIBE${BSDCFG_LIBE:+/}*/INDEX.$lang &&
-			return
+			$BSDCFG_LIBE${BSDCFG_LIBE:+/}*/INDEX.$lang && return
 		# No match, fall-thru to non-i18n sources
 	fi
 	awk -v keyword="$keyword" "$f_index_file_awk" \
-		$BSDCFG_LIBE${BSDCFG_LIBE:+/}*/INDEX
+		$BSDCFG_LIBE${BSDCFG_LIBE:+/}*/INDEX && return
+
+	# No match? Fall-thru to `local' libexec sources (add-on modules)
+
+	[ "$BSDCFG_LOCAL_LIBE" ] || return $FAILURE
+	if [ "$lang" ]; then
+		awk -v keyword="$keyword" "$f_index_file_awk" \
+			$BSDCFG_LOCAL_LIBE/*/INDEX.$lang && return
+		# No match, fall-thru to non-i18n sources
+	fi
+	awk -v keyword="$keyword" "$f_index_file_awk" \
+		$BSDCFG_LOCAL_LIBE/*/INDEX
 }
 
 # f_index_menusel_keyword $indexfile $pgm