fsemulation: replace sugar-base dependency by python-xdg

Use xdg.Mime and xdg.BaseDirectory instead of sugar.mime so we don't
depend on sugar-base.

1 files changed, 38 insertions, 8 deletions

diff --git a/fsemulation.py b/fsemulation.py
index 2a73310..8e89fef 100644
--- a/fsemulation.py
+++ b/fsemulation.py
@@ -26,8 +26,8 @@ import time
 
 import dbus
 import xapian
-
-import sugar.mime
+import xdg.BaseDirectory
+import xdg.Mime
 
 
 DS_DBUS_SERVICE = 'org.laptop.sugar.DataStore'
@@ -988,6 +988,7 @@ class FSEmulation(object):
         self._root_dir = RootDirectory(self, 0550)
         self._object_id_to_title_name = {}
         self._title_name_to_object_id = {}
+        self._mime_type_exts = self._load_mime_type_exts()
 
     def resolve(self, path, follow_links=False):
         assert isinstance(path, unicode)
@@ -1092,20 +1093,49 @@ class FSEmulation(object):
             del self._object_id_to_title_name[object_id]
 
     def _guess_extension(self, mime_type, object_id):
-        extension = None
-
         if not mime_type:
             file_name = self.data_store.get_data(object_id)
             if file_name:
                 try:
-                    mime_type = sugar.mime.get_for_file(file_name)
+                    mime_type = xdg.Mime.get_type(file_name)
                 finally:
                     os.remove(file_name)
 
-        if mime_type:
-            extension = sugar.mime.get_primary_extension(mime_type)
+        return self._mime_type_exts.get(mime_type)
+
+    def _load_mime_type_exts(self):
+        """Return a heuristic mapping from MIME type to file name extension
 
-        return extension
+        Return a map from MIME type to the best guess for its primary
+        (preferred) file name extension.
+
+        As most MIME type databases are not designed for this task, it's
+        just a crude heuristic that will be off even for common MIME
+        types.
+        """
+        globs2_paths = list(xdg.BaseDirectory.load_data_paths(
+            os.path.join('mime', 'globs2')))
+        rev_exts = {}
+        # System locations usually give a better estimate of the
+        # primary extension for a MIME type, so check them first.
+        for path in reversed(globs2_paths):
+            for line in open(path):
+                line = line.strip()
+                if line.startswith('#') or not line:
+                    continue
+                weight_, type_name, glob_pattern = line.split(':', 2)
+                if type_name in rev_exts:
+                    # There's already a better match (globs2 is sorted
+                    # by weight).
+                    continue
+                if not glob_pattern.startswith('*.'):
+                    continue
+                ext = glob_pattern[2:]
+                if '*' in ext or '[' in ext:
+                    continue
+                rev_exts[type_name] = ext
+
+        return rev_exts
 
 
 def safe_name(name):