bpo-42782: Fail fast for permission errors in shutil.move() (GH-24001)

* Fail fast in shutil.move() to avoid creating destination directories on failure.

Co-authored-by: Zackery Spytz <zspytz@gmail.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/Lib/shutil.py b/Lib/shutil.py
index f0e833d..89d924d 100644
--- a/Lib/shutil.py
+++ b/Lib/shutil.py
@@ -813,6 +813,12 @@ def move(src, dst, copy_function=copy2):
             if _destinsrc(src, dst):
                 raise Error("Cannot move a directory '%s' into itself"
                             " '%s'." % (src, dst))
+            if (_is_immutable(src)
+                    or (not os.access(src, os.W_OK) and os.listdir(src)
+                        and sys.platform == 'darwin')):
+                raise PermissionError("Cannot move the non-empty directory "
+                                      "'%s': Lacking write permission to '%s'."
+                                      % (src, src))
             copytree(src, real_dst, copy_function=copy_function,
                      symlinks=True)
             rmtree(src)
@@ -830,6 +836,11 @@ def _destinsrc(src, dst):
         dst += os.path.sep
     return dst.startswith(src)
 
+def _is_immutable(src):
+    st = _stat(src)
+    immutable_states = [stat.UF_IMMUTABLE, stat.SF_IMMUTABLE]
+    return hasattr(st, 'st_flags') and st.st_flags in immutable_states
+
 def _get_gid(name):
     """Returns a gid, given a group name."""
     if getgrnam is None or name is None: