bpo-45234: Fix FileNotFound exception raised instead of IsADirectoryError in shutil.copyfile() (GH-28421) (GH-28507)

This was a regression from fixing BPO-43219.
(cherry picked from commit b7eac52b46)

Co-authored-by: andrei kulakov <andrei.avk@gmail.com>

Lib/shutil.py

@@ -261,8 +261,9 @@ def copyfile(src, dst, *, follow_symlinks=True):
     if not follow_symlinks and _islink(src):
         os.symlink(os.readlink(src), dst)
     else:
+        with open(src, 'rb') as fsrc:
             try:
-            with open(src, 'rb') as fsrc, open(dst, 'wb') as fdst:
+                with open(dst, 'wb') as fdst:
                     # macOS
                     if _HAS_FCOPYFILE:
                         try:
@@ -287,10 +288,10 @@ def copyfile(src, dst, *, follow_symlinks=True):
 
             # Issue 43219, raise a less confusing exception
             except IsADirectoryError as e:
-            if os.path.exists(dst):
+                if not os.path.exists(dst):
-                raise
-            else:
                     raise FileNotFoundError(f'Directory does not exist: {dst}') from e
+                else:
+                    raise
 
     return dst
 

Lib/test/test_shutil.py

@@ -1147,6 +1147,28 @@ def test_copy_return_value(self):
             rv = fn(src, os.path.join(dst_dir, 'bar'))
             self.assertEqual(rv, os.path.join(dst_dir, 'bar'))
 
+    def test_copy_dir(self):
+        self._test_copy_dir(shutil.copy)
+
+    def test_copy2_dir(self):
+        self._test_copy_dir(shutil.copy2)
+
+    def _test_copy_dir(self, copy_func):
+        src_dir = self.mkdtemp()
+        src_file = os.path.join(src_dir, 'foo')
+        dir2 = self.mkdtemp()
+        dst = os.path.join(src_dir, 'does_not_exist/')
+        write_file(src_file, 'foo')
+        if sys.platform == "win32":
+            err = PermissionError
+        else:
+            err = IsADirectoryError
+        self.assertRaises(err, copy_func, dir2, src_dir)
+
+        # raise *err* because of src rather than FileNotFoundError because of dst
+        self.assertRaises(err, copy_func, dir2, dst)
+        copy_func(src_file, dir2)     # should not raise exceptions
+
     ### shutil.copyfile
 
     @support.skip_unless_symlink
@@ -1253,6 +1275,24 @@ def test_copyfile_nonexistent_dir(self):
         write_file(src_file, 'foo')
         self.assertRaises(FileNotFoundError, shutil.copyfile, src_file, dst)
 
+    def test_copyfile_copy_dir(self):
+        # Issue 45234
+        # test copy() and copyfile() raising proper exceptions when src and/or
+        # dst are directories
+        src_dir = self.mkdtemp()
+        src_file = os.path.join(src_dir, 'foo')
+        dir2 = self.mkdtemp()
+        dst = os.path.join(src_dir, 'does_not_exist/')
+        write_file(src_file, 'foo')
+        if sys.platform == "win32":
+            err = PermissionError
+        else:
+            err = IsADirectoryError
+
+        self.assertRaises(err, shutil.copyfile, src_dir, dst)
+        self.assertRaises(err, shutil.copyfile, src_file, src_dir)
+        self.assertRaises(err, shutil.copyfile, dir2, src_dir)
+
 
 class TestArchives(BaseTest, unittest.TestCase):
 

Misc/NEWS.d/next/Library/2021-09-17-11-20-55.bpo-45234.qUcTVt.rst

@@ -0,0 +1,3 @@
+Fixed a regression in :func:`~shutil.copyfile`, :func:`~shutil.copy`,
+:func:`~shutil.copy2` raising :exc:`FileNotFoundError` when source is a
+directory, which should raise :exc:`IsADirectoryError`