Fix xdg-mime default registration (#227)

* xdg-mime accepts the .desktop filename, not the full path

* add news

* Less invasive default registration, cleanup on removal

* clarify role of %f in the docs

* Update menuinst/platforms/linux.py

docs/source/defining-shortcuts.md

@@ -105,9 +105,10 @@ Each operating system has a slightly different way of associating a file type to
 Unix systems have the notion of MIME types, while Windows relies more on file name extensions.
 
 - On Linux, use the `MimeType` option. Remember to add the `%f` (single file) or `%F` (several
-  files) placeholders to your command so the paths are passed adequately. If you are defining a new
-  MIME type, you must fill the `glob_patterns` field by mapping the new MIME type to the file
-  extensions you want to associate with it.
+  files) placeholders to your command so the paths are passed adequately. Otherwise, your shortcut
+  might be deemed invalid and won't show up in "Open With" menus or similar UI elements of your
+  desktop. If you are defining a new MIME type, you must fill the `glob_patterns` field by mapping
+  the new MIME type to the file extensions you want to associate with it.
 - On Windows, use `file_extensions`. Remember to add the `%1` or `%*` placeholders to your command
   so the path of the opened file(s) is passed adequately.
 - On macOS, use `CFBundleDocumentTypes`. Requires no placeholder. The opened document will be

menuinst/platforms/linux.py

@@ -1,10 +1,10 @@
-"""
-"""
+""" """
 
 import os
 import shlex
 import shutil
 import time
+from configparser import ConfigParser
 from logging import getLogger
 from pathlib import Path
 from subprocess import CalledProcessError
@@ -286,11 +286,48 @@ def _register_mime_types(self, mime_types: Iterable[str], register: bool = True)
             if glob_pattern:
                 self._glob_pattern_for_mime_type(mime_type, glob_pattern, install=register)
 
+        mimeapps = self.menu.config_directory / "mimeapps.list"
         if register:
-            xdg_mime = shutil.which("xdg-mime")
-            if not xdg_mime:
-                log.debug("xdg-mime not found, not registering mime types as default.")
-            logged_run([xdg_mime, "default", self.location, *mime_types])
+            config = ConfigParser(default_section=None)
+            if mimeapps.is_file():
+                config.read(mimeapps)
+            log.debug("Registering %s to %s...", mime_types, mimeapps)
+            if "Default Applications" not in config.sections():
+                config.add_section("Default Applications")
+            if "Added Associations" not in config.sections():
+                config.add_section("Added Associations")
+            defaults = config["Default Applications"]
+            added = config["Added Associations"]
+            for mime_type in mime_types:
+                if mime_type not in defaults:
+                    # Do not override existing defaults
+                    defaults[mime_type] = self.location.name
+                if mime_type in added and self.location.name not in added[mime_type]:
+                    added[mime_type] = f"{added[mime_type]};{self.location.name}"
+                else:
+                    added[mime_type] = self.location.name
+            with open(mimeapps, "w") as f:
+                config.write(f, space_around_delimiters=False)
+        elif mimeapps.is_file():
+            # Remove entries
+            config = ConfigParser(default_section=None)
+            config.read(mimeapps)
+            log.debug("Deregistering %s from %s...", mime_types, mimeapps)
+            for section_name in "Default Applications", "Added Associations":
+                if section_name not in config.sections():
+                    continue
+                section = config[section_name]
+                for mimetype, desktop_files in section.items():
+                    if self.location.name == desktop_files:
+                        section.pop(mimetype)
+                    elif self.location.name in desktop_files.split(";"):
+                        section[mimetype] = ";".join(
+                            [x for x in desktop_files.split(";") if x != self.location.name]
+                        )
+                if not section.keys():
+                    config.remove_section(section_name)
+            with open(mimeapps, "w") as f:
+                config.write(f, space_around_delimiters=False)
 
         update_mime_database = shutil.which("update-mime-database")
         if update_mime_database:

news/227-xdg-mime-default

@@ -0,0 +1,19 @@
+### Enhancements
+
+* <news item>
+
+### Bug fixes
+
+* Fix default MIME type registration on Linux. (#226 via #227)
+
+### Deprecations
+
+* <news item>
+
+### Docs
+
+* <news item>
+
+### Other
+
+* <news item>