contrib: depdot: use processed package info

Instead of poorly parsing Makefiles using grep, use OpenWrt's processed
package info files. This fixes handling of DEPENDS fields spanning
multiple lines and adds support for source packages building multiple
binary packages.

Closes freifunk-gluon#2814

contrib/depdot.sh

@@ -2,7 +2,6 @@
 
 # Script to output the dependency graph of Gluon's packages
 # Limitations:
-#  * Works only if directory names and package names are the same (true for all Gluon packages)
 #  * Doesn't show dependencies through virtual packages correctly
 
 set -e
@@ -16,27 +15,42 @@ escape_name() {
 	echo -n "_$1" | tr -c '[:alnum:]' _
 }
 
-print_node () {
+print_node() {
 	echo "$(escape_name "$1") [label=\"$1\", shape=box];"
 }
 
 print_dep() {
 	echo "$(escape_name "$1") -> $(escape_name "$2");"
 }
 
-echo 'digraph G {'
-
-for makefile in ./package/*/Makefile; do
-	dir="$(dirname "$makefile")"
-	package="$(basename "$dir")"
-
-	deps=$(grep -w DEPENDS "$makefile" | cut -d= -f2 | tr -d +)
+print_package() {
+	local package="$1" depends="$2"
+	# shellcheck disable=SC2086
+	set -- $depends
 
 	print_node "$package"
-	for dep in $deps; do
+	for dep in "$@"; do
 		print_node "$dep"
 		print_dep "$package" "$dep"
 	done
+}
+
+make -C openwrt -s prepare-tmpinfo
+
+echo 'digraph G {'
+
+cat ./openwrt/tmp/info/.packageinfo-feeds_gluon_base_* | while read -r key value; do
+	case "$key" in
+	'Package:')
+		package="$value"
+		;;
+	'Depends:')
+		depends="${value//+/}"
+		;;
+	'@@')
+		print_package "$package" "$depends"
+		;;
+	esac
 done | sort -u
 
 popd >/dev/null