lifcycle: Add more validation to the config (#11382)

pkg/bucket/lifecycle/prefix.go

@@ -0,0 +1,50 @@
+/*
+ * MinIO Cloud Storage, (C) 2020 MinIO, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package lifecycle
+
+import (
+	"encoding/xml"
+)
+
+// Prefix holds the prefix xml tag in <Rule> and <Filter>
+type Prefix struct {
+	string
+	set bool
+}
+
+// UnmarshalXML - decodes XML data.
+func (p *Prefix) UnmarshalXML(d *xml.Decoder, start xml.StartElement) (err error) {
+	var s string
+	if err = d.DecodeElement(&s, &start); err != nil {
+		return err
+	}
+	*p = Prefix{string: s, set: true}
+	return nil
+}
+
+// MarshalXML - decodes XML data.
+func (p Prefix) MarshalXML(e *xml.Encoder, startElement xml.StartElement) error {
+	if !p.set {
+		return nil
+	}
+	return e.EncodeElement(p.string, startElement)
+}
+
+// String returns the prefix string
+func (p Prefix) String() string {
+	return p.string
+}