tempfiles: save a bunch of syscalls, by resetting the permissions only when we...

tempfiles: save a bunch of syscalls, by resetting the permissions only when we actually need to do it.

Signed-off-by: Mattia Rizzolo <mattia@debian.org>

diffoscope/tempfiles.py

@@ -58,15 +58,17 @@ def clean_all_temp_files():
     logger.debug("Cleaning %d temporary directories", len(_DIRS))
 
     for x in _DIRS:
-        # Recursively reset the permissions of temporary directories prior to
-        # deletion to ensure that non-writable permissions such as 0555 are
-        # removed and do not cause a traceback. (#891363)
-        for dirpath, ys, _ in os.walk(x.name):
-            for y in ys:
-                os.chmod(os.path.join(dirpath, y), 0o777)
-
         try:
             x.cleanup()
+        except PermissionError:
+            # Recursively reset the permissions of temporary directories prior to
+            # deletion to ensure that non-writable permissions such as 0555 are
+            # removed and do not cause a traceback. (#891363)
+            for dirpath, ys, _ in os.walk(x.name):
+                for y in ys:
+                    os.chmod(os.path.join(dirpath, y), 0o777)
+            # try removing it again now
+            x.cleanup()
         except FileNotFoundError:
             pass
         except: