fix: cleanup config KV parsing using madmin helpers (#15552)

internal/config/config.go

@@ -820,6 +820,33 @@ func GetSubSys(s string) (subSys string, inputs []string, tgt string, e error) {
 	return subSys, inputs, tgt, e
 }
 
+// kvFields - converts an input string of form "k1=v1 k2=v2" into
+// fields of ["k1=v1", "k2=v2"], the tokenization of each `k=v`
+// happens with the right number of input keys, if keys
+// input is empty returned value is empty slice as well.
+func kvFields(input string, keys []string) []string {
+	valueIndexes := make([]int, 0, len(keys))
+	for _, key := range keys {
+		i := strings.Index(input, key+KvSeparator)
+		if i == -1 {
+			continue
+		}
+		valueIndexes = append(valueIndexes, i)
+	}
+
+	sort.Ints(valueIndexes)
+	fields := make([]string, len(valueIndexes))
+	for i := range valueIndexes {
+		j := i + 1
+		if j < len(valueIndexes) {
+			fields[i] = strings.TrimSpace(input[valueIndexes[i]:valueIndexes[j]])
+		} else {
+			fields[i] = strings.TrimSpace(input[valueIndexes[i]:])
+		}
+	}
+	return fields
+}
+
 // SetKVS - set specific key values per sub-system.
 func (c Config) SetKVS(s string, defaultKVS map[string]KVS) (dynamic bool, err error) {
 	subSys, inputs, tgt, err := GetSubSys(s)
@@ -829,7 +856,7 @@ func (c Config) SetKVS(s string, defaultKVS map[string]KVS) (dynamic bool, err e
 
 	dynamic = SubSystemsDynamic.Contains(subSys)
 
-	fields := madmin.KvFields(inputs[1], defaultKVS[subSys].Keys())
+	fields := kvFields(inputs[1], defaultKVS[subSys].Keys())
 	if len(fields) == 0 {
 		return false, Errorf("sub-system '%s' cannot have empty keys", subSys)
 	}