Handle long paths when auto adding better

Havent really tested it since long paths arent officially supported but
this *should* mostly work

src/calibre/ebooks/metadata/meta.py

@@ -230,11 +230,13 @@ def opf_metadata(opfpath):
 def forked_read_metadata(original_path, tdir):
     from calibre.ebooks.metadata.opf2 import metadata_to_opf
     from calibre.ebooks.metadata.worker import run_import_plugins
+    from calibre.utils.filenames import make_long_path_useable
+
     path = run_import_plugins((original_path,), os.getpid(), tdir)[0]
     if path != original_path:
         with open(os.path.join(tdir, 'file_changed_by_plugins'), 'w') as f:
             f.write(os.path.abspath(path))
-    with open(path, 'rb') as f:
+    with open(make_long_path_useable(path), 'rb') as f:
         fmt = os.path.splitext(path)[1][1:].lower()
         f.seek(0, 2)
         sz = f.tell()

src/calibre/gui2/auto_add.py

@@ -6,7 +6,7 @@ import shutil
 import tempfile
 import time
 from qt.core import (
-    QApplication, QCursor, QFileSystemWatcher, QObject, Qt, QTimer, pyqtSignal
+    QApplication, QCursor, QFileSystemWatcher, QObject, Qt, QTimer, pyqtSignal,
 )
 from threading import Event, Thread
 
@@ -15,6 +15,7 @@ from calibre.db.adding import compile_rule, filter_filename
 from calibre.ebooks import BOOK_EXTENSIONS
 from calibre.gui2 import gprefs
 from calibre.gui2.dialogs.duplicates import DuplicatesQuestion
+from calibre.utils.filenames import make_long_path_useable
 from calibre.utils.tdir_in_cache import tdir_in_cache
 
 AUTO_ADDED = frozenset(BOOK_EXTENSIONS) - {'pdr', 'mbp', 'tan'}
@@ -86,15 +87,18 @@ class Worker(Thread):
         from calibre.ebooks.metadata.opf2 import metadata_to_opf
         from calibre.utils.ipc.simple_worker import WorkerError, fork_job
 
-        files = [x for x in os.listdir(self.path) if
+        def join(*x):
+            return make_long_path_useable(os.path.join(*x))
+
+        files = [x for x in os.listdir(join(self.path)) if
                     # Must not be in the process of being added to the db
                     x not in self.staging and
                     # Firefox creates 0 byte placeholder files when downloading
-                    os.stat(os.path.join(self.path, x)).st_size > 0 and
+                    os.stat(join(self.path, x)).st_size > 0 and
                     # Must be a file
-                    os.path.isfile(os.path.join(self.path, x)) and
+                    os.path.isfile(join(self.path, x)) and
                     # Must have read and write permissions
-                    os.access(os.path.join(self.path, x), os.R_OK|os.W_OK) and
+                    os.access(join(self.path, x), os.R_OK|os.W_OK) and
                     # Must be a known ebook file type
                     self.is_filename_allowed(x)
                 ]
@@ -104,7 +108,7 @@ class Worker(Thread):
 
         def safe_mtime(x):
             try:
-                return os.path.getmtime(os.path.join(self.path, x))
+                return os.path.getmtime(join(self.path, x))
             except OSError:
                 return time.time()
 
@@ -116,7 +120,7 @@ class Worker(Thread):
             # application for writing. We will get notified by
             # QFileSystemWatcher when writing is completed, so ignore for now.
             try:
-                open(f, 'rb').close()
+                open(make_long_path_useable(f), 'rb').close()
             except:
                 continue
             tdir = tempfile.mkdtemp(dir=self.tdir)
@@ -259,7 +263,7 @@ class AutoAdder(QObject):
                 mi.tags = map_tags(mi.tags, gprefs['tag_map_on_add_rules'])
             if gprefs.get('author_map_on_add_rules'):
                 from calibre.ebooks.metadata.author_mapper import (
-                    compile_rules, map_authors
+                    compile_rules, map_authors,
                 )
                 new_authors = map_authors(mi.authors, compile_rules(gprefs['author_map_on_add_rules']))
                 if new_authors != mi.authors: