update: make it pass shellcheck

Without that fix, running 'shellcheck -x build' produces the following
errors/warnings:
    In update line 81:
    case "${option}" in
    ^-- SC1009 (info):
    The mentioned syntax error was in this case expression.

    In update line 82:
    list)
    ^-- SC1073 (error):
    Couldn't parse this case item. Fix to allow more checks.

    In update line 92:
    all)
       ^-- SC1072 (error):
       Fix any mentioned problems and try again.
       ^-- SC1074 (error):
       Did you forget the ;; after the previous case item?

After fixing these and rerunning 'shellcheck -x build', we then have
the following errors/warnings:
    In update line 23:
    [ "x${DEBUG+set}" = 'xset' ] && set -v
      ^-------------^ SC2268 (style):
    Avoid x-prefix in comparisons as it no longer serves a purpose.

    In update line 32:
    ls -d resources/packages/*/update/ | \
    ^-- SC2012 (info):
    Use find instead of ls to better handle non-alphanumeric filenames.

    In update line 40:
    ls -d resources/packages/"${package}"/update/* | \
    ^-- SC2012 (info):
    Use find instead of ls to better handle non-alphanumeric filenames.

    In update line 95:
    resources/packages/"${package}"/update/"${option}" $@
                                                       ^-- SC2068 (error):
    Double quote array expansions to avoid re-splitting elements.

    In update line 102:
    "${pkg_dir}"/update/"${option}" $@
                                    ^-- SC2068 (error):
    Double quote array expansions to avoid re-splitting elements.
so we fix them as well.

Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>
Acked-by: Adrien 'neox' Bourmault <neox@gnu.org>

tests/lint

@@ -44,6 +44,7 @@ run_shellcheck \
     build \
     download \
     modify \
+    update \
     resources/packages/descriptors/distclean \
     resources/packages/flashrom/distclean \
     resources/packages/grub/distclean \

update

@@ -20,7 +20,7 @@
 #    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
-[ "x${DEBUG+set}" = 'xset' ] && set -v
+[ "${DEBUG+set}" = 'set' ] && set -v
 set -u -e
 
 projectname="$(cat projectname)"
@@ -28,17 +28,26 @@ projectname="$(cat projectname)"
 
 . resources/scripts/misc/sysexits.sh
 
+list_update_paths() {
+	find resources/packages \
+		-mindepth 2 -maxdepth 2 \
+		-type d \
+		-name "update" \
+		-printf "%P\n"
+}
+
 list_packages() {
-	ls -d resources/packages/*/update/ | \
+	list_update_paths | \
-		sed 's#resources/packages/##' | \
 		sed 's#/.*##'
 }
 
 # Takes exactly one package as parameter
 listoptions() {
 	package="${1}"
-	ls -d resources/packages/"${package}"/update/* | \
+	find resources/packages/"${package}/update/" \
-	    sed 's#resources/packages/'"${package}"'/update/##'
+		-mindepth 1 -maxdepth 1 \
+		-type f \
+	        -printf "%P\n"
 }
 
 help() {
@@ -89,8 +98,10 @@ if [ $# -gt 1 ]; then
 			   "${package}"
 			listoptions "${package}"
 		fi
+		;;
 	all)
 		for option in $(listoptions "${package}"); do
+			# shellcheck disable=SC2068
 			resources/packages/"${package}"/update/"${option}" $@
 		done
 		;;
@@ -98,6 +109,7 @@ if [ $# -gt 1 ]; then
 		if [ -d resources/packages/"${package}"/update ]; then
 			pkg_dir=resources/packages/"${package}"
 			if [ -f "${pkg_dir}"/update/"${option}" ]; then
+				# shellcheck disable=SC2068
 				"${pkg_dir}"/update/"${option}" $@
 			else
 				help
@@ -111,6 +123,7 @@ if [ $# -gt 1 ]; then
 			    "Invalid package '${package}'." \
 			    " See './update --help'."
 		fi
+		;;
 	esac
 else
 	help