[macOS] Emit FileModifiedEvent on permission change (#815)

* [fsevents] emit permission changes as modified events

alongside other metadata modifications

* added test for chmod events

* added changelog entry

changelog.rst

@@ -9,7 +9,8 @@ Changelog
 2021-xx-x • `full history <https://github.com/gorakhargosh/watchdog/compare/v2.1.3...master>`__
 
 - [watchmedo] Fix usage of ``os.setsid()`` and ``os.killpg()`` Unix-only functions.  (`#809 <https://github.com/gorakhargosh/watchdog/pull/809>`_)
-- Thanks to our beloved contributors: @replabrobin, @BoboTiG
+- [mac] Fix missing ``FileModifiedEvent`` on permission or ownership changes of a file.  (`#809 <https://github.com/gorakhargosh/watchdog/pull/814>`_)
+- Thanks to our beloved contributors: @replabrobin, @BoboTiG, @SamSchott
 
 2.1.3
 ~~~~~

src/watchdog/observers/fsevents.py

@@ -156,6 +156,11 @@ def _is_historic_created_event(self, event):
 
         return in_history or before_start
 
+    @staticmethod
+    def _is_meta_mod(event):
+        """Returns True if the event indicates a change in metadata."""
+        return event.is_inode_meta_mod or event.is_xattr_mod or event.is_owner_change
+
     def queue_events(self, timeout, events):
 
         if logger.getEffectiveLevel() <= logging.DEBUG:
@@ -209,7 +214,7 @@ def queue_events(self, timeout, events):
 
                 self._fs_view.add(event.inode)
 
-                if event.is_modified or event.is_inode_meta_mod or event.is_xattr_mod:
+                if event.is_modified or self._is_meta_mod(event):
                     self._queue_modified_event(event, src_path, src_dirname)
 
                 self._queue_deleted_event(event, src_path, src_dirname)
@@ -222,7 +227,7 @@ def queue_events(self, timeout, events):
 
                 self._fs_view.add(event.inode)
 
-                if event.is_modified or event.is_inode_meta_mod or event.is_xattr_mod:
+                if event.is_modified or self._is_meta_mod(event):
                     self._queue_modified_event(event, src_path, src_dirname)
 
                 if event.is_renamed:
@@ -247,7 +252,7 @@ def queue_events(self, timeout, events):
 
                         events.remove(dst_event)
 
-                        if dst_event.is_modified or dst_event.is_inode_meta_mod or dst_event.is_xattr_mod:
+                        if dst_event.is_modified or self._is_meta_mod(dst_event):
                             self._queue_modified_event(dst_event, dst_path, dst_dirname)
 
                         if dst_event.is_removed:

tests/test_emitter.py

@@ -15,6 +15,7 @@
 # limitations under the License.
 
 import os
+import stat
 import time
 import pytest
 import logging
@@ -195,6 +196,21 @@ def test_modify():
         assert isinstance(event, FileClosedEvent)
 
 
+@pytest.mark.flaky(max_runs=5, min_passes=1, rerun_filter=rerun_filter)
+def test_chmod():
+    mkfile(p('a'))
+    start_watching()
+
+    # Note: We use S_IREAD here because chmod on Windows only
+    # allows setting the read-only flag.
+    os.chmod(p('a'), stat.S_IREAD)
+
+    expect_event(FileModifiedEvent(p('a')))
+
+    # Reset permissions to allow cleanup.
+    os.chmod(p('a'), stat.S_IWRITE)
+
+
 @pytest.mark.flaky(max_runs=5, min_passes=1, rerun_filter=rerun_filter)
 def test_move():
     mkdir(p('dir1'))