Fix send_file's attachment_filename to work with non-ascii filenames

flask/helpers.py

@@ -41,6 +41,7 @@
 from .globals import session, _request_ctx_stack, _app_ctx_stack, \
      current_app, request
 from ._compat import string_types, text_type
+from unidecode import unidecode
 
 
 # sentinel
@@ -534,8 +535,11 @@ def send_file(filename_or_fp, mimetype=None, as_attachment=False,
         if attachment_filename is None:
             raise TypeError('filename unavailable, required for '
                             'sending as attachment')
+        filename_dict = {
+            'filename': unidecode(text_type(attachment_filename)),
+            'filename*': "UTF-8''%s" % url_quote(attachment_filename)}
         headers.add('Content-Disposition', 'attachment',
-                    filename=attachment_filename)
+                    **filename_dict)
 
     if current_app.use_x_sendfile and filename:
         if file is not None:

setup.py

@@ -75,6 +75,7 @@ def hello():
         'Jinja2>=2.4',
         'itsdangerous>=0.21',
         'click>=2.0',
+        'unidecode',
     ],
     classifiers=[
         'Development Status :: 4 - Beta',

tests/test_helpers.py

@@ -560,6 +560,18 @@ def test_attachment(self):
             assert options['filename'] == 'index.txt'
             rv.close()
 
+    def test_attachment_with_utf8_filename(self):
+        app = flask.Flask(__name__)
+        with app.test_request_context():
+            with open(os.path.join(app.root_path, 'static/index.html')) as f:
+                rv = flask.send_file(f, as_attachment=True,
+                                     attachment_filename=u'Ñandú／pingüino.txt')
+                content_disposition = set(rv.headers['Content-Disposition'].split(';'))
+                assert content_disposition == set(['attachment',
+                                                   ' filename="Nandu/pinguino.txt"',
+                                                   " filename*=UTF-8''%C3%91and%C3%BA%EF%BC%8Fping%C3%BCino.txt"])
+                rv.close()
+
     def test_static_file(self):
         app = flask.Flask(__name__)
         # default cache timeout is 12 hours

tox.ini

@@ -27,6 +27,7 @@ deps=
     devel: git+https://github.com/pallets/itsdangerous.git
     devel: git+https://github.com/jek/blinker.git
     simplejson: simplejson
+    unidecode
 
 [testenv:docs]
 deps = sphinx