libmakepkg: increase robustness of the detection of array variables

Extract array detection into its own utility function that ensures
extglob is enabled.

Suggested-by: Dave Reisner <dreisner@archlinux.org>
Signed-off-by: Allan McRae <allan@archlinux.org>

1 files changed, 17 insertions, 0 deletions

diff --git a/scripts/libmakepkg/util/util.sh b/scripts/libmakepkg/util/util.sh
index 3c996dac..675e75de 100644
--- a/scripts/libmakepkg/util/util.sh
+++ b/scripts/libmakepkg/util/util.sh
@@ -37,6 +37,23 @@ in_array() {
 	return 1 # Not Found
 }
 
+# tests if a variable is an array
+is_array() {
+	local v=$1
+	local ret=1
+
+	# this function requires extglob - save current options to restore later
+	local shellopts=$(shopt -p)
+	shopt -s extglob
+
+	if [[ $(declare -p "$i") == declare\ -*([[:alnum:]])a*([[:alnum:]])\ * ]]; then
+		ret=0
+	fi
+
+	eval "$shellopts"
+	return $ret
+}
+
 # Canonicalize a directory path if it exists
 canonicalize_path() {
 	local path="$1";