sambacc: generalize dir fd sync'ing - apply it to xattr set

Adapt and continue Shachar's previous patch to ensure that
after setting xattrs on the dir we try to commit it to permanent
storage.


Signed-off-by: John Mulligan <[email protected]>

Author: phlogistonjohn

sambacc/permissions.py

@@ -18,6 +18,7 @@
 
 from __future__ import annotations
 
+import contextlib
 import datetime
 import errno
 import logging
@@ -47,6 +48,19 @@ def path(self) -> str:
         ...  # pragma: no cover
 
 
+@contextlib.contextmanager
+def _opendir(path: str) -> typing.Iterator[int]:
+    dfd: int = os.open(path, os.O_DIRECTORY)
+    try:
+        yield dfd
+        os.fsync(dfd)
+    except OSError:
+        os.sync()
+        raise
+    finally:
+        os.close(dfd)
+
+
 class NoopPermsHandler:
     def __init__(
         self,
@@ -145,14 +159,8 @@ def _set_perms(self) -> None:
         # yeah, this is really simple compared to all the state management
         # stuff.
         path = self._full_path()
-        dfd = os.open(path, os.O_DIRECTORY)
-        try:
+        with _opendir(path) as dfd:
             os.fchmod(dfd, self._mode)
-            os.fsync(dfd)
-        except OSError:
-            os.sync()
-        finally:
-            os.close(dfd)
 
     def _timestamp(self) -> str:
         return datetime.datetime.now().strftime("%s")
@@ -163,7 +171,8 @@ def _set_status(self) -> None:
         val = f"{self._prefix}/{ts}"
         path = self._full_path()
         _logger.debug("setting xattr %r=%r: %r", self._xattr, val, self._path)
-        return xattr.set(path, self._xattr, val, nofollow=True)
+        with _opendir(path) as dfd:
+            xattr.set(dfd, self._xattr, val, nofollow=True)
 
 
 class AlwaysPosixPermsHandler(InitPosixPermsHandler):