Linux installer: Manually presereve the defaults.list mimetype association file to workaround buggy xdg-desktop-menu implementations in some distros. Fixes #926559 (File associations)

src/calibre/linux.py

@@ -40,6 +40,46 @@ entry_points = {
                             ],
       }
 
+class PreserveMIMEDefaults(object):
+
+    def __init__(self):
+        self.initial_values = {}
+
+    def __enter__(self):
+        def_data_dirs = '/usr/local/share:/usr/share'
+        paths = os.environ.get('XDG_DATA_DIRS', def_data_dirs)
+        paths = paths.split(':')
+        paths.append(os.environ.get('XDG_DATA_HOME', os.path.expanduser(
+            '~/.local/share')))
+        paths = list(filter(os.path.isdir, paths))
+        if not paths:
+            # Env var had garbage in it, ignore it
+            paths = def_data_dirs.split(':')
+        paths = list(filter(os.path.isdir, paths))
+        self.paths = {os.path.join(x, 'applications/defaults.list') for x in
+                paths}
+        self.initial_values = {}
+        for x in self.paths:
+            try:
+                with open(x, 'rb') as f:
+                    self.initial_values[x] = f.read()
+            except:
+                self.initial_values[x] = None
+
+    def __exit__(self, *args):
+        for path, val in self.initial_values.iteritems():
+            if val is None:
+                try:
+                    os.remove(path)
+                except:
+                    pass
+            elif os.path.exists(path):
+                with open(path, 'r+b') as f:
+                    if f.read() != val:
+                        f.seek(0)
+                        f.truncate()
+                        f.write(val)
+
 # Uninstall script {{{
 UNINSTALL = '''\
 #!{python}
@@ -333,12 +373,10 @@ class PostInstall:
 
     def setup_desktop_integration(self): # {{{
         try:
-
             self.info('Setting up desktop integration...')
 
-
+            with TemporaryDirectory() as tdir, CurrentDir(tdir), \
-            with TemporaryDirectory() as tdir:
+                                PreserveMIMEDefaults():
-                with CurrentDir(tdir):
                 render_img('mimetypes/lrf.png', 'calibre-lrf.png')
                 check_call('xdg-icon-resource install --noupdate --context mimetypes --size 128 calibre-lrf.png application-lrf', shell=True)
                 self.icon_resources.append(('mimetypes', 'application-lrf', '128'))