Fixed #1110 -- Do not report symlink create/delete as a move in DirectorySnapshotDiff

changelog.rst

@@ -26,6 +26,7 @@ Changelog
 - [core] Fixed ``generate_sub_moved_events()`` corrupting paths when the directory name appears multiple times in the path. (`#1158 <https://github.com/gorakhargosh/watchdog/pull/1158>`__)
 - Thanks to our beloved contributors: @BoboTiG, @tybug, @Corentin-pro, @kirkhansen, @JoachimCoenen, @blitztide
 - [core] Call ``task_done()`` for the stop sentinel in ``dispatch_events()`` to prevent ``join()`` from hanging. (`#1159 <https://github.com/gorakhargosh/watchdog/pull/1159>`__)
+- [utils] Fixed ``DirectorySnapshotDiff`` reporting a newly created symlink as a move of its target (and a removed symlink as a move onto its target), so ``PollingObserver`` now emits a create/delete event to match the native observers. (`#1176 <https://github.com/gorakhargosh/watchdog/pull/1176>`__)
 
 6.0.0
 ~~~~~

src/watchdog/utils/dirsnapshot.py

@@ -98,15 +98,23 @@ def get_inode(directory: DirectorySnapshot, full_path: bytes | str) -> int | tup
         for path in set(deleted):
             inode = ref.inode(path)
             new_path = snapshot.path(inode)
-            if new_path:
+            # Only treat this as a move if the inode is now reachable through a
+            # genuinely new path. A symlink (or hard link) shares its target's
+            # inode, so ``new_path`` may still point at the unchanged target,
+            # which is not a move.
+            if new_path and (new_path not in ref.paths or ref.inode(new_path) != inode):
                 # file is not deleted but moved
                 deleted.remove(path)
                 moved.add((path, new_path))
 
         for path in set(created):
             inode = snapshot.inode(path)
             old_path = ref.path(inode)
-            if old_path:
+            # Only treat this as a move if the inode's previous path is really
+            # gone. A symlink (or hard link) shares its target's inode, so
+            # ``old_path`` may still exist with that inode, which means this is a
+            # creation, not a move.
+            if old_path and (old_path not in snapshot.paths or snapshot.inode(old_path) != inode):
                 created.remove(path)
                 moved.add((old_path, path))
 

tests/test_snapshot_diff.py

@@ -6,10 +6,12 @@
 import time
 from unittest.mock import patch
 
+import pytest
+
 from watchdog.utils import platform
 from watchdog.utils.dirsnapshot import DirectorySnapshot, DirectorySnapshotDiff, EmptyDirectorySnapshot
 
-from .shell import mkdir, mv, rm, touch
+from .shell import mkdir, mv, rm, symlink, touch
 
 
 def wait():
@@ -90,6 +92,35 @@ def test_move_replace(p):
     assert diff.files_created == []
 
 
+@pytest.mark.skipif(platform.is_windows(), reason="Creating symlinks requires privileges on Windows.")
+def test_create_symlink_to_existing_file(p):
+    # A new symlink shares its target's inode (the default stat follows symlinks),
+    # so it must not be mistaken for a move of the still-present target. See #1110.
+    mkdir(p("dir"))
+    touch(p("dir", "a"))
+    ref = DirectorySnapshot(p(""))
+    symlink("a", p("dir", "a.link"))
+    diff = DirectorySnapshotDiff(ref, DirectorySnapshot(p("")))
+    assert diff.files_created == [p("dir", "a.link")]
+    assert diff.files_moved == []
+    assert diff.files_deleted == []
+
+
+@pytest.mark.skipif(platform.is_windows(), reason="Creating symlinks requires privileges on Windows.")
+def test_delete_symlink_to_existing_file(p):
+    # Removing a symlink whose target remains must be reported as a deletion, not
+    # a move onto the target that keeps the shared inode. See #1110.
+    mkdir(p("dir"))
+    touch(p("dir", "a"))
+    symlink("a", p("dir", "a.link"))
+    ref = DirectorySnapshot(p(""))
+    rm(p("dir", "a.link"))
+    diff = DirectorySnapshotDiff(ref, DirectorySnapshot(p("")))
+    assert diff.files_deleted == [p("dir", "a.link")]
+    assert diff.files_moved == []
+    assert diff.files_created == []
+
+
 def test_dir_modify_on_create(p):
     ref = DirectorySnapshot(p(""))
     wait()