Add support for O_DIRECTORY and O_NOFOLLOW flags

- flags are considered in os.open if present

CHANGES.md

@@ -23,6 +23,10 @@ The released versions correspond to PyPI releases.
 * fixed handling of `dirfd` in `os.symlink` (see [#968](../../issues/968))
 * add missing `follow_symlink` argument to `os.link` (see [#973](../../issues/973))
 
+### Enhancements
+* added support for `O_NOFOLLOW` and `O_DIRECTORY` flags in `os.open`
+  (see [#972](../../issues/972) and [#974](../../issues/974))
+
 ## [Version 5.3.5](https://pypi.python.org/pypi/pyfakefs/5.3.5) (2024-01-30)
 Fixes a regression.
 

pyfakefs/fake_os.py

@@ -247,6 +247,18 @@ def open(
             else:
                 mode = 0o777 & ~self._umask()
 
+        has_directory_flag = (
+            hasattr(os, "O_DIRECTORY") and flags & os.O_DIRECTORY == os.O_DIRECTORY
+        )
+        if has_directory_flag and not self.filesystem.isdir(path):
+            raise OSError(errno.ENOTDIR, "path is not a directory", path)
+
+        has_follow_flag = (
+            hasattr(os, "O_NOFOLLOW") and flags & os.O_NOFOLLOW == os.O_NOFOLLOW
+        )
+        if has_follow_flag and self.filesystem.islink(path):
+            raise OSError(errno.ELOOP, "path is a symlink", path)
+
         has_tmpfile_flag = (
             hasattr(os, "O_TMPFILE") and flags & os.O_TMPFILE == os.O_TMPFILE
         )

pyfakefs/tests/fake_os_test.py

@@ -565,6 +565,42 @@ def test_open_raises_with_trailing_separator_windows(self):
         self.check_windows_only()
         self.check_open_raises_with_trailing_separator(errno.EINVAL)
 
+    @unittest.skipIf(not hasattr(os, "O_DIRECTORY"), "opening directory not supported")
+    def test_open_raises_if_not_dir(self):
+        self.check_posix_only()
+        file_path = self.make_path("file.txt")
+        self.create_file(file_path, contents="foo")
+        with self.assertRaises(NotADirectoryError):
+            self.os.open(file_path, os.O_RDONLY | os.O_DIRECTORY)
+        dir_path = self.make_path("dir")
+        self.create_dir(dir_path)
+        with self.assertRaises(IsADirectoryError):
+            self.os.open(dir_path, os.O_RDWR | os.O_DIRECTORY)
+
+    @unittest.skipIf(not hasattr(os, "O_NOFOLLOW"), "NOFOLLOW attribute not supported")
+    def test_open_nofollow_symlink_raises(self):
+        self.skip_if_symlink_not_supported()
+        file_path = self.make_path("file.txt")
+        self.create_file(file_path, contents="foo")
+        link_path = self.make_path("link")
+        self.create_symlink(link_path, file_path)
+        with self.assertRaises(OSError) as cm:
+            self.os.open(link_path, os.O_RDONLY | os.O_NOFOLLOW)
+        assert cm.exception.errno == errno.ELOOP
+
+    @unittest.skipIf(not hasattr(os, "O_NOFOLLOW"), "NOFOLLOW attribute not supported")
+    def test_open_nofollow_symlink_as_parent_works(self):
+        self.skip_if_symlink_not_supported()
+        dir_path = self.make_path("dir")
+        self.create_dir(dir_path)
+        link_path = self.make_path("link")
+        self.create_symlink(link_path, dir_path)
+        file_path = self.os.path.join(link_path, "file.txt")
+        self.create_file(file_path, contents="foo")
+        fd = self.os.open(file_path, os.O_RDONLY | os.O_NOFOLLOW)
+        self.assertGreater(fd, 0)
+        self.os.close(fd)
+
     def test_lexists_with_trailing_separator_linux_windows(self):
         self.check_linux_and_windows()
         self.skip_if_symlink_not_supported()
@@ -5298,7 +5334,6 @@ def test_scandir_stat_nlink(self):
                 self.assertEqual(1, self.os.stat(self.file_path).st_nlink)
 
     @unittest.skipIf(not hasattr(os, "O_DIRECTORY"), "opening directory not supported")
-    @unittest.skipIf(sys.version_info < (3, 7), "fd not supported for scandir")
     def test_scandir_with_fd(self):
         # regression test for #723
         temp_dir = self.make_path("tmp", "dir")