Avoid shadowing variables and enable checks to avoid them during build

Makefile

@@ -17,8 +17,10 @@ verifiers: getdeps vet fmt lint cyclo
 
 vet:
 	@echo "Running $@:"
-	@GO15VENDOREXPERIMENT=1 go vet .
+	@GO15VENDOREXPERIMENT=1 go tool vet -all *.go
-	@GO15VENDOREXPERIMENT=1 go vet github.com/minio/minio/pkg...
+	@GO15VENDOREXPERIMENT=1 go tool vet -all ./pkg
+	@GO15VENDOREXPERIMENT=1 go tool vet -shadow=true *.go
+	@GO15VENDOREXPERIMENT=1 go tool vet -shadow=true ./pkg
 
 fmt:
 	@echo "Running $@:"

pkg/donut/donut-v1.go

@@ -525,7 +525,8 @@ func (donut API) getBucketMetadataReaders() (map[int]io.ReadCloser, *probe.Error
 	disks := make(map[int]disk.Disk)
 	var err *probe.Error
 	for _, node := range donut.nodes {
-		nDisks, err := node.ListDisks()
+		nDisks := make(map[int]disk.Disk)
+		nDisks, err = node.ListDisks()
 		if err != nil {
 			return nil, err.Trace()
 		}
@@ -596,14 +597,15 @@ func (donut API) makeDonutBucket(bucketName, acl string) *probe.Error {
 	if _, ok := donut.buckets[bucketName]; ok {
 		return probe.NewError(BucketExists{Bucket: bucketName})
 	}
-	bucket, bucketMetadata, err := newBucket(bucketName, acl, donut.config.DonutName, donut.nodes)
+	bkt, bucketMetadata, err := newBucket(bucketName, acl, donut.config.DonutName, donut.nodes)
 	if err != nil {
 		return err.Trace()
 	}
 	nodeNumber := 0
-	donut.buckets[bucketName] = bucket
+	donut.buckets[bucketName] = bkt
 	for _, node := range donut.nodes {
-		disks, err := node.ListDisks()
+		disks := make(map[int]disk.Disk)
+		disks, err = node.ListDisks()
 		if err != nil {
 			return err.Trace()
 		}
@@ -666,11 +668,11 @@ func (donut API) listDonutBuckets() *probe.Error {
 		}
 		bucketName := splitDir[0]
 		// we dont need this once we cache from makeDonutBucket()
-		bucket, _, err := newBucket(bucketName, "private", donut.config.DonutName, donut.nodes)
+		bkt, _, err := newBucket(bucketName, "private", donut.config.DonutName, donut.nodes)
 		if err != nil {
 			return err.Trace()
 		}
-		donut.buckets[bucketName] = bucket
+		donut.buckets[bucketName] = bkt
 	}
 	return nil
 }

pkg/donut/management.go

@@ -24,8 +24,8 @@ import (
 // Info - return info about donut configuration
 func (donut API) Info() (nodeDiskMap map[string][]string, err *probe.Error) {
 	nodeDiskMap = make(map[string][]string)
-	for nodeName, node := range donut.nodes {
+	for nodeName, n := range donut.nodes {
-		disks, err := node.ListDisks()
+		disks, err := n.ListDisks()
 		if err != nil {
 			return nil, err.Trace()
 		}
@@ -43,11 +43,11 @@ func (donut API) AttachNode(hostname string, disks []string) *probe.Error {
 	if hostname == "" || len(disks) == 0 {
 		return probe.NewError(InvalidArgument{})
 	}
-	node, err := newNode(hostname)
+	n, err := newNode(hostname)
 	if err != nil {
 		return err.Trace()
 	}
-	donut.nodes[hostname] = node
+	donut.nodes[hostname] = n
 	for i, d := range disks {
 		newDisk, err := disk.New(d)
 		if err != nil {
@@ -56,7 +56,7 @@ func (donut API) AttachNode(hostname string, disks []string) *probe.Error {
 		if err := newDisk.MakeDir(donut.config.DonutName); err != nil {
 			return err.Trace()
 		}
-		if err := node.AttachDisk(newDisk, i); err != nil {
+		if err := n.AttachDisk(newDisk, i); err != nil {
 			return err.Trace()
 		}
 	}

pkg/server/api/headers.go

@@ -62,18 +62,18 @@ func setCommonHeaders(w http.ResponseWriter, acceptsType string, contentLength i
 // Write error response headers
 func encodeErrorResponse(response interface{}, acceptsType contentType) []byte {
 	var bytesBuffer bytes.Buffer
-	var encoder encoder
+	var e encoder
 	// write common headers
 	switch acceptsType {
 	case xmlContentType:
-		encoder = xml.NewEncoder(&bytesBuffer)
+		e = xml.NewEncoder(&bytesBuffer)
 	case jsonContentType:
-		encoder = json.NewEncoder(&bytesBuffer)
+		e = json.NewEncoder(&bytesBuffer)
 	// by default even if unknown Accept header received handle it by sending XML contenttype response
 	default:
-		encoder = xml.NewEncoder(&bytesBuffer)
+		e = xml.NewEncoder(&bytesBuffer)
 	}
-	encoder.Encode(response)
+	e.Encode(response)
 	return bytesBuffer.Bytes()
 }
 
@@ -105,14 +105,14 @@ func setObjectHeaders(w http.ResponseWriter, metadata donut.ObjectMetadata, cont
 }
 
 func encodeSuccessResponse(response interface{}, acceptsType contentType) []byte {
-	var encoder encoder
+	var e encoder
 	var bytesBuffer bytes.Buffer
 	switch acceptsType {
 	case xmlContentType:
-		encoder = xml.NewEncoder(&bytesBuffer)
+		e = xml.NewEncoder(&bytesBuffer)
 	case jsonContentType:
-		encoder = json.NewEncoder(&bytesBuffer)
+		e = json.NewEncoder(&bytesBuffer)
 	}
-	encoder.Encode(response)
+	e.Encode(response)
 	return bytesBuffer.Bytes()
 }

pkg/server/api/object-handlers.go

@@ -67,13 +67,14 @@ func (api Minio) GetObjectHandler(w http.ResponseWriter, req *http.Request) {
 
 	metadata, err := api.Donut.GetObjectMetadata(bucket, object, signature)
 	if err == nil {
-		httpRange, err := getRequestedRange(req.Header.Get("Range"), metadata.Size)
+		var hrange *httpRange
+		hrange, err = getRequestedRange(req.Header.Get("Range"), metadata.Size)
 		if err != nil {
 			writeErrorResponse(w, req, InvalidRange, acceptsContentType, req.URL.Path)
 			return
 		}
-		setObjectHeaders(w, metadata, httpRange)
+		setObjectHeaders(w, metadata, hrange)
-		if _, err := api.Donut.GetObject(w, bucket, object, httpRange.start, httpRange.length); err != nil {
+		if _, err = api.Donut.GetObject(w, bucket, object, hrange.start, hrange.length); err != nil {
 			// unable to write headers, we've already printed data. Just close the connection.
 			log.Error.Println(err.Trace())
 			return