web: Use Unicode paths to send files on Windows under Python 2

[robot3498712]

Hi,

beets version 1.4.3
Python version 2.7.11
plugins: web

Python 2.7.11 (v2.7.11:6d1b6a68f775, Dec 5 2015, 20:32:19) [MSC v.1500 32 bit (Intel)] on win32

Following flask error was encountered when calling item/file method for non-ascii items:

[2017-06-14 21:36:27,233] ERROR in app: Exception on /item/52117/file [GET]
Traceback (most recent call last):
  File "c:\python\lib\site-packages\flask\app.py", line 1982, in wsgi_app
    response = self.full_dispatch_request()
  File "c:\python\lib\site-packages\flask\app.py", line 1614, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "c:\python\lib\site-packages\flask_cors\extension.py", line 161, in wrapped_function
    return cors_after_request(app.make_response(f(*args, **kwargs)))
  File "c:\python\lib\site-packages\flask\app.py", line 1517, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "c:\python\lib\site-packages\flask\app.py", line 1612, in full_dispatch_request
    rv = self.dispatch_request()
  File "c:\python\lib\site-packages\flask\app.py", line 1598, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "c:\python\lib\site-packages\beetsplug\web\__init__.py", line 209, in item_file
    attachment_filename=os.path.basename(util.py3_path(item.path)),
  File "c:\python\lib\site-packages\flask\helpers.py", line 549, in send_file
    file = open(filename, 'rb')
IOError: [Errno 2] No such file or directory: 'PATH_REDACTED\\01 Marta Kubis\xcc\x8cova\xcc\x81 - Tak Dej Se K Na\xcc\x81m A Projdem Svet.flac'
127.0.0.1 - - [14/Jun/2017 21:36:27] "GET /item/52117/file HTTP/1.1" 500 -

https://github.com/beetbox/beets/blob/master/beetsplug/web/__init__.py

Unicode path fixes it for me:

def item_file(item_id):
    item = g.lib.get_item(item_id)
    response = flask.send_file(
        unicode(item.path, "utf-8", errors="ignore"),
        as_attachment=True,
        attachment_filename=os.path.basename(item.path),
    )
    response.headers['Content-Length'] = os.path.getsize(unicode(item.path, "utf-8", errors="ignore"))
    return response

[sampsyo]

Hi! Thanks for reporting this, and for investigating the problem.

Since you're on Windows, it does makes sense that Flask might want Unicode paths. Here's one other thing to try: can you try changing that argument to use util.syspath instead of util.py3_path? That is, the line would be:

        util.syspath(item.path),

Another alternative would be to try running beets under Python 3.6 instead of 2.7—I think this might "just work" in that setting.

[robot3498712]

Hi sampsyo,

thank you for quick reply and solution!

beets version 1.4.4

I can confirm following works:

def item_file(item_id):
    item = g.lib.get_item(item_id)
    response = flask.send_file(
        util.syspath(item.path),
        as_attachment=True,
        attachment_filename=os.path.basename(util.py3_path(item.path)),
    )
    response.headers['Content-Length'] = os.path.getsize(util.syspath(item.path))
    return response

Upgrading python definitely is something to consider .. eventually maybe ;)
Ciao

[sampsyo]

Thanks! That's helpful to know.

I think the solution is to use syspath on Windows and py3_path on other platforms. This should be a straightforward fix—a pull request would be very helpful if you have a chance!