change server side uploader to fully streaming based (#1066)

this PR fixes the behavior to avoid `/tmp` folder as
staging directory for large uploads, instead rely on
the client upload stream itself to upload the object
entirely.

restapi/user_objects.go

@@ -21,11 +21,11 @@ import (
 	"fmt"
 	"io"
 	"log"
-	"mime/multipart"
 	"net/http"
 	"path"
 	"path/filepath"
 	"regexp"
+	"strconv"
 	"strings"
 	"time"
 
@@ -468,16 +468,35 @@ func uploadFiles(ctx context.Context, client MinioClient, params user_api.PostBu
 		prefix = *params.Prefix
 	}
 
-	// get object files from request
-	o, err := getFormFiles(params.HTTPRequest)
+	// parse a request body as multipart/form-data.
+	// 32 << 20 is default max memory
+	mr, err := params.HTTPRequest.MultipartReader()
 	if err != nil {
 		return err
 	}
-	defer o.Close()
 
-	// upload files one by one
-	for _, obj := range o.Files() {
-		if err := uploadObject(ctx, client, params.BucketName, path.Join(prefix, obj.name), obj.size, obj.file); err != nil {
+	for {
+		p, err := mr.NextPart()
+		if err == io.EOF {
+			break
+		}
+
+		size, err := strconv.ParseInt(p.FormName(), 10, 64)
+		if err != nil {
+			return err
+		}
+
+		contentType := p.Header.Get("content-type")
+		if contentType == "" {
+			contentType = mimedb.TypeByExtension(filepath.Ext(p.FileName()))
+		}
+
+		_, err = client.putObject(ctx, params.BucketName, path.Join(prefix, p.FileName()), p, size, minio.PutObjectOptions{
+			ContentType:      contentType,
+			DisableMultipart: true, // Do not upload as multipart stream for console uploader.
+		})
+
+		if err != nil {
 			return err
 		}
 	}
@@ -485,71 +504,6 @@ func uploadFiles(ctx context.Context, client MinioClient, params user_api.PostBu
 	return nil
 }
 
-type objectFile struct {
-	name string
-	size int64
-	file multipart.File
-}
-
-type objectFiles struct {
-	files []objectFile
-	form  *multipart.Form
-}
-
-func (o objectFiles) Files() []objectFile {
-	return o.files
-}
-
-func (o objectFiles) Close() error {
-	for _, fl := range o.files {
-		fl.file.Close()
-	}
-	if o.form != nil {
-		return o.form.RemoveAll()
-	}
-	return nil
-}
-
-// getFormFiles parses the request body and gets all the files from the Request
-// it includes name, size and file content
-func getFormFiles(r *http.Request) (o objectFiles, err error) {
-	if r == nil {
-		return o, errors.New("http.Request is nil")
-	}
-
-	// parse a request body as multipart/form-data.
-	// 32 << 20 is default max memory
-	if err := r.ParseMultipartForm(32 << 20); err != nil {
-		return o, err
-	}
-
-	for fileName, files := range r.MultipartForm.File {
-		if len(files) > 0 {
-			f, err := files[0].Open()
-			if err != nil {
-				return o, err
-			}
-			o.files = append(o.files, objectFile{
-				name: fileName,
-				size: files[0].Size,
-				file: f,
-			})
-		}
-	}
-	o.form = r.MultipartForm
-
-	return o, nil
-}
-
-func uploadObject(ctx context.Context, client MinioClient, bucket, object string, size int64, reader io.ReadCloser) error {
-	contentType := mimedb.TypeByExtension(filepath.Ext(object))
-	_, err := client.putObject(ctx, bucket, object, reader, size, minio.PutObjectOptions{
-		ContentType:      contentType,
-		DisableMultipart: true, // Do not upload as multipart stream for console uploader.
-	})
-	return err
-}
-
 // getShareObjectResponse returns a share object url
 func getShareObjectResponse(session *models.Principal, params user_api.ShareObjectParams) (*string, *models.Error) {
 	ctx := context.Background()