[#3298|Core] Fix pickle loading non-ascii state error

When trying to load a torrents.state from version 1.3 users were
encountering the following error:

    UnicodeDecodeError: 'ascii' codec can't decode byte

This was due to the way that Python 2 was pickling state with torrent
filenames that contained non-ascii characters and Python 3 was
unpickling the state using ascii encoding and failing. The fix is to
specify utf-8 encoding when loading torrents.state.

deluge/core/torrentmanager.py

@@ -25,7 +25,7 @@ from twisted.internet.task import LoopingCall
 
 import deluge.component as component
 from deluge._libtorrent import lt
-from deluge.common import archive_files, decode_bytes, get_magnet_info, is_magnet
+from deluge.common import PY2, archive_files, decode_bytes, get_magnet_info, is_magnet
 from deluge.configmanager import ConfigManager, get_config_dir
 from deluge.core.authmanager import AUTH_LEVEL_ADMIN
 from deluge.core.torrent import Torrent, TorrentOptions, sanitize_filepath
@@ -809,7 +809,10 @@ class TorrentManager(component.Component):
 
             try:
                 with open(filepath, 'rb') as _file:
-                    state = pickle.load(_file)
+                    if PY2:
+                        state = pickle.load(_file)
+                    else:
+                        state = pickle.load(_file, encoding='utf8')
             except (IOError, EOFError, pickle.UnpicklingError) as ex:
                 message = 'Unable to load {}: {}'.format(filepath, ex)
                 log.error(message)

deluge/tests/data/utf8_filename_torrents.state

@@ -0,0 +1,85 @@
+(ideluge.core.torrentmanager
+TorrentManagerState
+p1
+(dp2
+S'torrents'
+p3
+(lp4
+(ideluge.core.torrentmanager
+TorrentState
+p5
+(dp6
+S'max_download_speed'
+p7
+I-1
+sS'move_completed_path'
+p8
+S'/home/calum/Downloads'
+p9
+sS'paused'
+p10
+I00
+sS'max_upload_slots'
+p11
+I-1
+sS'prioritize_first_last'
+p12
+I00
+sS'max_connections'
+p13
+I-1
+sS'compact'
+p14
+I00
+sS'queue'
+p15
+I0
+sS'file_priorities'
+p16
+(lp17
+I4
+asS'filename'
+p18
+S'\xc2\xa2.torrent'
+p19
+sS'max_upload_speed'
+p20
+I-1
+sS'save_path'
+p21
+S'/home/calum/Downloads'
+p22
+sS'time_added'
+p23
+F1573563097.749759
+sS'total_uploaded'
+p24
+I0
+sS'torrent_id'
+p25
+S'80d81d55ef3b85f3c1b634c362e014b35594dc71'
+p26
+sS'auto_managed'
+p27
+I01
+sS'stop_at_ratio'
+p28
+I00
+sS'move_completed'
+p29
+I00
+sS'trackers'
+p30
+(lp31
+sS'magnet'
+p32
+NsS'remove_at_ratio'
+p33
+I00
+sS'stop_ratio'
+p34
+F2
+sS'is_finished'
+p35
+I00
+sbasb.

deluge/tests/test_torrentmanager.py

@@ -7,6 +7,8 @@
 
 from __future__ import unicode_literals
 
+import os
+import shutil
 import warnings
 from base64 import b64encode
 
@@ -28,7 +30,7 @@ warnings.resetwarnings()
 
 class TorrentmanagerTestCase(BaseTestCase):
     def set_up(self):
-        common.set_tmp_config_dir()
+        self.config_dir = common.set_tmp_config_dir()
         self.rpcserver = RPCServer(listen=False)
         self.core = Core()
         self.core.config.config['lsd'] = False
@@ -118,3 +120,12 @@ class TorrentmanagerTestCase(BaseTestCase):
         self.assertRaises(
             InvalidTorrentError, self.tm.remove, 'torrentidthatdoesntexist'
         )
+
+    def test_open_state_from_python2(self):
+        """Open a Python2 state with a UTF-8 encoded torrent filename."""
+        shutil.copy(
+            common.get_test_data_file('utf8_filename_torrents.state'),
+            os.path.join(self.config_dir, 'state', 'torrents.state'),
+        )
+        state = self.tm.open_state()
+        self.assertEqual(len(state.torrents), 1)