From bd616602befaa395186fe3c6d448d98b4bee8a85 Mon Sep 17 00:00:00 2001
From: garenchan <1412950785@qq.com>
Date: Thu, 4 Oct 2018 20:42:24 +0800
Subject: [PATCH] Make sure the attachment filename is text type. If attachment
 filename is bytes type and contains non-ascii coded bytes, then the following
 ASCII encoding process will trigger UnicodeDecodeError exception.

Fix issue #2933.
---
 flask/helpers.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/flask/helpers.py b/flask/helpers.py
index 7679a496..4d747ad6 100644
--- a/flask/helpers.py
+++ b/flask/helpers.py
@@ -568,6 +568,9 @@ def send_file(filename_or_fp, mimetype=None, as_attachment=False,
                             'sending as attachment')
 
         try:
+            # Make sure the attachment filename is text type.
+            if not isinstance(attachment_filename, text_type):
+                attachment_filename = attachment_filename.decode('utf-8')
             attachment_filename = attachment_filename.encode('ascii')
         except UnicodeEncodeError:
             filenames = {