abuild: try to validate maintainer address

abuild will error when the maintainer is set but is not a RFC822 address

abuild.in

@@ -210,7 +210,7 @@ default_sanitycheck() {
 	[ -n "$pkggroup" ] && spell_error pkggroup pkggroups
 	[ -n "$subpackage" ] && spell_error subpackage subpackages
 
-	grep '^# Maintainer:' $APKBUILD >/dev/null || warning "No maintainer"
+	get_maintainer || die "Provide a valid RFC822 maintainer address"
 
 	makedepends_has 'g++' && warning "g++ should not be in makedepends"
 	return 0
@@ -721,9 +721,25 @@ git_last_commit() {
 	git log --format=oneline -n 1 "$startdir" | awk '{print $1}'
 }
 
+# this will try to check for a valid rfc822 address
+check_rfc822() {
+	local address="$1"
+	case "$address" in
+		*[A-Za-z0-9]*\ \<*@*.*\>) ;;
+		*) return 1 ;;
+	esac
+}
+
 get_maintainer() {
 	if [ -z "$maintainer" ]; then
 		maintainer=$(awk -F': ' '/\# *Maintainer/ {print $2}' "$APKBUILD")
+		# remove surrounding whitespace
+		maintainer=$(echo "$maintainer" | xargs)
+		if ! [ -z "$maintainer" ]; then
+			check_rfc822 "$maintainer" || return 1
+		else
+			warning "No maintainer"
+		fi
 	fi
 }
 
@@ -789,7 +805,6 @@ EOF
 	fi
 	echo "commit = $last_commit" >> "$pkginfo"
 
-	get_maintainer
 	if [ -n "$maintainer" ]; then
 		echo "maintainer = $maintainer" >> "$pkginfo"
 	fi