Implement proper delimiter and prefix handling

With this change Minio server now responds with, delimited
'object names' in conjunction with prefix filtering

~~~
<ListBucketResult>
  <Name>example-bucket</Name>
  <Prefix></Prefix>
  <Marker></Marker>
  <MaxKeys>1000</MaxKeys>
  <Delimiter>/</Delimiter>
  <IsTruncated>false</IsTruncated>
  <Contents>
    <Key>sample.html</Key>
    <LastModified>2011-02-26T01:56:20.000Z</LastModified>
    <ETag>example-bucket#sample.html</ETag>
    <Size>142863</Size>
    <Owner>
      <ID>minio</ID>
      <DisplayName>minio</DisplayName>
    </Owner>
    <StorageClass>STANDARD</StorageClass>
  </Contents>
  <CommonPrefixes>
    <Prefix>photos/</Prefix>
  </CommonPrefixes>
</ListBucketResult>
~~~

~~~
<ListBucketResult>
  <Name>example-bucket</Name>
  <Prefix>photos/2006/</Prefix>
  <Marker></Marker>
  <MaxKeys>1000</MaxKeys>
  <Delimiter>/</Delimiter>
  <IsTruncated>false</IsTruncated>

  <CommonPrefixes>
    <Prefix>photos/2006/feb/</Prefix>
  </CommonPrefixes>
  <CommonPrefixes>
    <Prefix>photos/2006/jan/</Prefix>
  </CommonPrefixes>
</ListBucketResult>
~~~

pkg/api/minioapi/bucket_handlers.go

@@ -45,7 +45,7 @@ func (server *minioApi) listObjectsHandler(w http.ResponseWriter, req *http.Requ
 	switch err := err.(type) {
 	case nil: // success
 		{
-			response := generateObjectsListResult(bucket, objects, resources.IsTruncated)
+			response := generateObjectsListResult(bucket, objects, resources)
 			w.Write(writeObjectHeadersAndResponse(w, response, acceptsContentType))
 		}
 	case mstorage.BucketNotFound:

pkg/api/minioapi/definitions.go

@@ -34,10 +34,8 @@ type ObjectListResponse struct {
 	MaxKeys        int
 	Delimiter      string
 	IsTruncated    bool
-	Contents       []*Item `xml:,innerxml`
-	CommonPrefixes struct {
-		Prefix string
-	} `xml:,innerxml`
+	Contents       []*Item   `xml:,innerxml`
+	CommonPrefixes []*Prefix `xml:,innerxml`
 }
 
 // Bucket list response format
@@ -49,6 +47,10 @@ type BucketListResponse struct {
 	} `xml:,innerxml` // Buckets are nested
 }
 
+type Prefix struct {
+	Prefix string
+}
+
 // Bucket struct
 type Bucket struct {
 	Name         string

pkg/api/minioapi/response.go

@@ -68,8 +68,9 @@ func (b ItemKey) Less(i, j int) bool { return b[i].Key < b[j].Key }
 //
 // output:
 // populated struct that can be serialized to match xml and json api spec output
-func generateObjectsListResult(bucket string, objects []mstorage.ObjectMetadata, isTruncated bool) ObjectListResponse {
+func generateObjectsListResult(bucket string, objects []mstorage.ObjectMetadata, bucketResources mstorage.BucketResourcesMetadata) ObjectListResponse {
 	var contents []*Item
+	var prefixes []*Prefix
 	var owner = Owner{}
 	var data = ObjectListResponse{}
 
@@ -78,6 +79,9 @@ func generateObjectsListResult(bucket string, objects []mstorage.ObjectMetadata,
 
 	for _, object := range objects {
 		var content = &Item{}
+		if object.Key == "" {
+			continue
+		}
 		content.Key = object.Key
 		content.LastModified = object.Created.Format(dateFormat)
 		content.ETag = object.ETag
@@ -89,7 +93,16 @@ func generateObjectsListResult(bucket string, objects []mstorage.ObjectMetadata,
 	sort.Sort(ItemKey(contents))
 	data.Name = bucket
 	data.Contents = contents
-	data.MaxKeys = MAX_OBJECT_LIST
-	data.IsTruncated = isTruncated
+	data.MaxKeys = bucketResources.Maxkeys
+	data.Prefix = bucketResources.Prefix
+	data.Delimiter = bucketResources.Delimiter
+	data.Marker = bucketResources.Marker
+	data.IsTruncated = bucketResources.IsTruncated
+	for _, prefix := range bucketResources.CommonPrefixes {
+		var prefixItem = &Prefix{}
+		prefixItem.Prefix = prefix
+		prefixes = append(prefixes, prefixItem)
+	}
+	data.CommonPrefixes = prefixes
 	return data
 }