[s3] Put bucket lifecycle configuration (#5510)

weed/s3api/s3api_policy.go

@@ -47,8 +47,14 @@ type Filter struct {
 
 // Prefix holds the prefix xml tag in <Rule> and <Filter>
 type Prefix struct {
-	string
-	set bool
+	XMLName xml.Name `xml:"Prefix"`
+	set     bool
+
+	val string
+}
+
+func (p Prefix) String() string {
+	return p.val
 }
 
 // MarshalXML encodes Prefix field into an XML form.
@@ -56,11 +62,21 @@ func (p Prefix) MarshalXML(e *xml.Encoder, startElement xml.StartElement) error
 	if !p.set {
 		return nil
 	}
-	return e.EncodeElement(p.string, startElement)
+	return e.EncodeElement(p.val, startElement)
+}
+
+func (p *Prefix) UnmarshalXML(d *xml.Decoder, startElement xml.StartElement) error {
+	prefix := ""
+	_ = d.DecodeElement(&prefix, &startElement)
+	*p = Prefix{set: true, val: prefix}
+	return nil
 }
 
 // MarshalXML encodes Filter field into an XML form.
 func (f Filter) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
+	if !f.set {
+		return nil
+	}
 	if err := e.EncodeToken(start); err != nil {
 		return err
 	}