fix: utils StreamResponseBody() memory use for large get requests

s3api/controllers/base.go

@@ -644,16 +644,12 @@ func (c S3ApiController) GetActions(ctx *fiber.Ctx) error {
 	}
 
 	if res.Body != nil {
-		err := utils.StreamResponseBody(ctx, res.Body)
-		if err != nil {
-			SendResponse(ctx, nil,
-				&MetaOpts{
-					Logger:      c.logger,
-					MetricsMng:  c.mm,
-					Action:      metrics.ActionGetObject,
-					BucketOwner: parsedAcl.Owner,
-				})
+		// -1 will stream response body until EOF if content length not set
+		contentLen := -1
+		if res.ContentLength != nil {
+			contentLen = int(*res.ContentLength)
 		}
+		utils.StreamResponseBody(ctx, res.Body, contentLen)
 	}
 
 	return SendResponse(ctx, nil,

s3api/utils/utils.go

@@ -204,27 +204,10 @@ func SetResponseHeaders(ctx *fiber.Ctx, headers []CustomHeader) {
 }
 
 // Streams the response body by chunks
-func StreamResponseBody(ctx *fiber.Ctx, rdr io.ReadCloser) error {
-	buf := make([]byte, 4096) // 4KB chunks
-	defer rdr.Close()
-	for {
-		n, err := rdr.Read(buf)
-		if n > 0 {
-			_, writeErr := ctx.Write(buf[:n])
-			if writeErr != nil {
-				return fmt.Errorf("write chunk: %w", writeErr)
-			}
-		}
-		if err != nil {
-			if errors.Is(err, io.EOF) {
-				break
-			}
-
-			return fmt.Errorf("read chunk: %w", err)
-		}
-	}
-
-	return nil
+func StreamResponseBody(ctx *fiber.Ctx, rdr io.ReadCloser, bodysize int) {
+	// SetBodyStream will call Close() on the reader when the stream is done
+	// since rdr is a ReadCloser
+	ctx.Context().SetBodyStream(rdr, bodysize)
 }
 
 func IsValidBucketName(bucket string) bool {