get: Fix reading an object if its size is unknown

Getting an object and reading it doesn't work as expected when S3 server
doesn't return the object content length, which happens sometimes with
Google Cloud Service.

api-get-object.go

@@ -328,14 +328,14 @@ func (o *Object) setOffset(bytesRead int64) error {
 	// Update the currentOffset.
 	o.currOffset += bytesRead
 
-	if o.currOffset >= o.objectInfo.Size {
+	if o.objectInfo.Size > -1 && o.currOffset >= o.objectInfo.Size {
 		return io.EOF
 	}
 	return nil
 }
 
 // Read reads up to len(b) bytes into b. It returns the number of
-// bytes read (0 <= n <= len(p)) and any error encountered. Returns
+// bytes read (0 <= n <= len(b)) and any error encountered. Returns
 // io.EOF upon end of file.
 func (o *Object) Read(b []byte) (n int, err error) {
 	if o == nil {
@@ -442,7 +442,7 @@ func (o *Object) ReadAt(b []byte, offset int64) (n int, err error) {
 	if o.objectInfoSet {
 		// If offset is negative than we return io.EOF.
 		// If offset is greater than or equal to object size we return io.EOF.
-		if offset >= o.objectInfo.Size || offset < 0 {
+		if (o.objectInfo.Size > -1 && offset >= o.objectInfo.Size) || offset < 0 {
 			return 0, io.EOF
 		}
 	}
@@ -542,16 +542,20 @@ func (o *Object) Seek(offset int64, whence int) (n int64, err error) {
 	default:
 		return 0, ErrInvalidArgument(fmt.Sprintf("Invalid whence %d", whence))
 	case 0:
-		if offset > o.objectInfo.Size {
+		if o.objectInfo.Size > -1 && offset > o.objectInfo.Size {
 			return 0, io.EOF
 		}
 		o.currOffset = offset
 	case 1:
-		if o.currOffset+offset > o.objectInfo.Size {
+		if o.objectInfo.Size > -1 && o.currOffset+offset > o.objectInfo.Size {
 			return 0, io.EOF
 		}
 		o.currOffset += offset
 	case 2:
+		// If we don't know the object size return an error for io.SeekEnd
+		if o.objectInfo.Size < 0 {
+			return 0, ErrInvalidArgument("Whence END is not supported when the object size is unknown")
+		}
 		// Seeking to positive offset is valid for whence '2', but
 		// since we are backing a Reader we have reached 'EOF' if
 		// offset is positive.

api-stat.go

@@ -21,8 +21,6 @@ import (
 	"strconv"
 	"strings"
 	"time"
-
-	"github.com/minio/minio-go/pkg/s3utils"
 )
 
 // BucketExists verify if bucket exists and you have permission to access it.
@@ -126,12 +124,13 @@ func (c Client) statObject(bucketName, objectName string, reqHeaders RequestHead
 	md5sum := strings.TrimPrefix(resp.Header.Get("ETag"), "\"")
 	md5sum = strings.TrimSuffix(md5sum, "\"")
 
-	// Content-Length is not valid for Google Cloud Storage, do not verify.
+	// Parse content length is exists
 	var size int64 = -1
-	if !s3utils.IsGoogleEndpoint(c.endpointURL) {
-		// Parse content length.
-		size, err = strconv.ParseInt(resp.Header.Get("Content-Length"), 10, 64)
+	contentLengthStr := resp.Header.Get("Content-Length")
+	if contentLengthStr != "" {
+		size, err = strconv.ParseInt(contentLengthStr, 10, 64)
 		if err != nil {
+			// Content-Length is not valid
 			return ObjectInfo{}, ErrorResponse{
 				Code:       "InternalError",
 				Message:    "Content-Length is invalid. " + reportIssue,