container/mts/meta: added GetAllAsMap function

This function is very similar to GetAll, except that is returns a map[string]string rather
than a [][2]string. It's become apparent that a map[string]string might be more useful in
some circumstances.

container/mts/meta/meta.go

@@ -216,6 +216,34 @@ func GetAll(d []byte) ([][2]string, error) {
 	return all, nil
 }
 
+// GetAllAsMap returns a map containging keys and values from a slice d containing
+// AusOcean metadata.
+func GetAllAsMap(d []byte) (map[string]string, error) {
+	err := checkMeta(d)
+	if err != nil {
+		return nil, err
+	}
+
+	// Skip the header, which is our data length and version.
+	d = d[headSize:]
+
+	// Each metadata entry (key and value) is seperated by a tab, so split at tabs
+	// to get individual entries.
+	entries := strings.Split(string(d), "\t")
+
+	// Go through entries and add to all map.
+	all := make(map[string]string)
+	for _, entry := range entries {
+		// Keys and values are seperated by '=', so split and check that len(kv)=2.
+		kv := strings.Split(entry, "=")
+		if len(kv) != 2 {
+			return nil, errUnexpectedMetaFormat
+		}
+		all[kv[0]] = kv[1]
+	}
+	return all, nil
+}
+
 // checkHeader checks that a valid metadata header exists in the given data.
 func checkMeta(d []byte) error {
 	if len(d) == 0 || d[0] != 0 || binary.BigEndian.Uint16(d[2:headSize]) != uint16(len(d[headSize:])) {