}
					sset.Add(kv.Key)
				}
			}
			e.Encode(kvs)
		}
	}
	return &buf, d.Err()
}

// parsePostPolicyForm - Parse JSON policy string into typed PostPolicyForm structure.
func parsePostPolicyForm(r io.Reader) (PostPolicyForm, error) {
	reader, err := sanitizePolicy(r)
	if err != nil {
		return PostPolicyForm{}, err
	}

	d := json.NewDecoder(reader)