[TrueCloudLab#40] Add param to configure xml decoder

This parameter enables parsing xml body without
xmlns="http://s3.amazonaws.com/doc/2006-03-01/" attribute
for CompleteMultipartUpload requests

Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>

internal/xml/decoder.go

@@ -0,0 +1,38 @@
+package xml
+
+import (
+	"encoding/xml"
+	"io"
+	"sync"
+)
+
+const awsDefaultNamespace = "http://s3.amazonaws.com/doc/2006-03-01/"
+
+type DecoderProvider struct {
+	mu                               sync.RWMutex
+	defaultXMLNSForCompleteMultipart bool
+}
+
+func NewDecoderProvider(defaultNamespace bool) *DecoderProvider {
+	return &DecoderProvider{
+		defaultXMLNSForCompleteMultipart: defaultNamespace,
+	}
+}
+
+func (d *DecoderProvider) NewCompleteMultipartDecoder(r io.Reader) *xml.Decoder {
+	dec := xml.NewDecoder(r)
+
+	d.mu.RLock()
+	if d.defaultXMLNSForCompleteMultipart {
+		dec.DefaultSpace = awsDefaultNamespace
+	}
+	d.mu.RUnlock()
+
+	return dec
+}
+
+func (d *DecoderProvider) UseDefaultNamespaceForCompleteMultipart(useDefaultNamespace bool) {
+	d.mu.Lock()
+	d.defaultXMLNSForCompleteMultipart = useDefaultNamespace
+	d.mu.Unlock()
+}