[type/__localedef] Differentiate between OSes and better handling of normalized locale names

cdist/conf/type/__localedef/gencode-remote

@@ -1,6 +1,7 @@
 #!/bin/sh -e
 #
 # 2013-2019 Nico Schottelius (nico-cdist at schottelius.org)
+# 2020 Dennis Camera (dennis.camera at ssrq-sds-fds.ch)
 #
 # This file is part of cdist.
 #
@@ -17,35 +18,16 @@
 # You should have received a copy of the GNU General Public License
 # along with cdist. If not, see <http://www.gnu.org/licenses/>.
 #
+# Manage system locales using localedef(1).
 #
-# Let localedef do the magic
-#
-
-locale="$__object_id"
-
-# Hardcoded, create a pull request with
-# branching on $os in case it is at another location
-alias=/usr/share/locale/locale.alias
-
-input=$(echo "$locale" | cut -d . -f 1)
-charmap=$(echo "$locale" | cut -d . -f 2)
-
-# Adding locale? The name is de_CH.UTF-8
-# Removing locale? The name is de_CH.utf8.
-# W-T-F!
-locale_remove=$(echo "$locale" | sed 's/UTF-8/utf8/')
 
 state_is=$(cat "${__object:?}/explorer/state")
 state_should=$(cat "${__object:?}/parameter/state")
 
-os=$(cat "$__global/explorer/os")
-
-# Nothing to be done on alpine
-case "$os" in
-    alpine)
-        exit 0
-        ;;
-esac
+test "${state_should}" = 'present' -o "${state_should}" = 'absent' || {
+	printf 'Invalid state: %s\n' "${state_should}" >&2
+	exit 1
+}
 
 # NOTE: If state explorer fails (e.g. locale(1) missing), the following check
 #       will always fail and let definition/removal run.
@@ -54,16 +36,81 @@ then
 	exit 0
 fi
 
-case ${state_should}
+locale=${__object_id:?}
+os=$(cat "${__global:?}/explorer/os")
+
+if expr "${locale}" : '.*/' >/dev/null
+then
+	printf 'Paths as locales are not supported.\n' >&2
+	printf '__object_id is: %s\n' "${locale}" >&2
+	exit 1
+fi
+
+parse_locale() {
+	# This function will split locales into their parts. Locale strings are
+	# usually of the form: [language[_territory][.codeset][@modifier]]
+	# For simplicity, language and territory are not separated by this function.
+	# Old Linux systems were also using "english" or "german" as locale strings.
+	# Usage: parse_locale locale_str lang_var codeset_var modifier_var
+	eval "${2:?}"="$(expr "$1" : '\([^.@]*\)')"
+	eval "${3:?}"="$(expr "$1" : '[^.]*\.\([^@]*\)')"
+	eval "${4:?}"="$(expr "$1" : '.*@\(.*\)$')"
+}
+
+format_locale() {
+	# Usage: format_locale language codeset modifier
+	printf '%s' "$1"
+	test -z "$2" || printf '.%s' "$2"
+	test -z "$3" || printf '@%s' "$3"
+	printf '\n'
+}
+
+gnu_normalize_codeset() {
+	echo "$*" | tr -cd '[:alnum:]' | tr '[:upper:]' '[:lower:]'
+}
+
+
+: "${lang=}" "${codeset=}" "${modifier=}"  # declare variables for shellcheck
+parse_locale "${locale}" lang codeset modifier
+
+
+case ${os}
 in
-    present)
-        echo localedef -A "$alias" -f "$charmap" -i "$input" "$locale"
+	(alpine|openwrt)
+		printf '%s does not support locales.\n' "${os}" >&2
+		exit 1
 		;;
-    absent)
-        echo localedef --delete-from-archive "$locale_remove"
+	(archlinux|debian|devuan|ubuntu|suse|centos|fedora|redhat|scientific)
+		# FIXME: The code below only works for glibc-based installations.
+
+		# NOTE: Hardcoded, create a pull request in case it is at another
+		#       location for some opther distro.
+		# NOTE: locale.alias can be symlinked (e.g. Debian)
+		aliasfile='/usr/share/locale/locale.alias'
+
+		case ${state_should}
+		in
+			(present)
+				input=$(format_locale "${lang}" '' "${modifier}")
+				cat <<-EOF
+				set --
+				if test -e '${aliasfile}'
+				then
+					set -- -A '${aliasfile}'
+				fi
+
+				localedef -i '${input}' -f '${codeset}' "\$@" '${locale}'
+				EOF
 				;;
-    *)
-        echo "Unsupported state: $state" >&2
+			(absent)
+				localename=$(format_locale "${lang}" "$(gnu_normalize_codeset "${codeset}")" "${modifier}")
+				printf "localedef --delete-from-archive '%s'\n" "${localename}"
+				;;
+		esac
+		;;
+	(*)
+		echo "Your operating system (${os}) is currently not supported by this type (${__type##*/})." >&2
+		echo "Please contribute an implementation for it if you can." >&2
 		exit 1
 		;;
 esac