RustPython · youknowone · Feb 3, 2026 · Feb 1, 2026 · Feb 2, 2026 · Feb 2, 2026
diff --git a/Lib/os.py b/Lib/os.py
@@ -10,7 +10,7 @@
   - os.extsep is the extension separator (always '.')
   - os.altsep is the alternate pathname separator (None or '/')
   - os.pathsep is the component separator used in $PATH etc
-  - os.linesep is the line separator in text files ('\r' or '\n' or '\r\n')
+  - os.linesep is the line separator in text files ('\n' or '\r\n')
   - os.defpath is the default search path for executables
   - os.devnull is the file path of the null device ('/dev/null', etc.)
 
@@ -64,6 +64,10 @@ def _get_exports_list(module):
         from posix import _have_functions
     except ImportError:
         pass
+    try:
+        from posix import _create_environ
+    except ImportError:
+        pass
 
     import posix
     __all__.extend(_get_exports_list(posix))
@@ -88,6 +92,10 @@ def _get_exports_list(module):
         from nt import _have_functions
     except ImportError:
         pass
+    try:
+        from nt import _create_environ
+    except ImportError:
+        pass
 
 else:
     raise ImportError('no os specific module found')
@@ -366,61 +374,45 @@ def walk(top, topdown=True, onerror=None, followlinks=False):
         # minor reason when (say) a thousand readable directories are still
         # left to visit.
         try:
-            scandir_it = scandir(top)
+            with scandir(top) as entries:
+                for entry in entries:
+                    try:
+                        if followlinks is _walk_symlinks_as_files:
+                            is_dir = entry.is_dir(follow_symlinks=False) and not entry.is_junction()
+                        else:
+                            is_dir = entry.is_dir()
+                    except OSError:
+                        # If is_dir() raises an OSError, consider the entry not to
+                        # be a directory, same behaviour as os.path.isdir().
+                        is_dir = False
+
+                    if is_dir:
+                        dirs.append(entry.name)
+                    else:
+                        nondirs.append(entry.name)
+
+                    if not topdown and is_dir:
+                        # Bottom-up: traverse into sub-directory, but exclude
+                        # symlinks to directories if followlinks is False
+                        if followlinks:
+                            walk_into = True
+                        else:
+                            try:
+                                is_symlink = entry.is_symlink()
+                            except OSError:
+                                # If is_symlink() raises an OSError, consider the
+                                # entry not to be a symbolic link, same behaviour
+                                # as os.path.islink().
+                                is_symlink = False
+                            walk_into = not is_symlink
+
+                        if walk_into:
+                            walk_dirs.append(entry.path)
         except OSError as error:
             if onerror is not None:
                 onerror(error)
             continue
 
-        cont = False
-        with scandir_it:
-            while True:
-                try:
-                    try:
-                        entry = next(scandir_it)
-                    except StopIteration:
-                        break
-                except OSError as error:
-                    if onerror is not None:
-                        onerror(error)
-                    cont = True
-                    break
-
-                try:
-                    if followlinks is _walk_symlinks_as_files:
-                        is_dir = entry.is_dir(follow_symlinks=False) and not entry.is_junction()
-                    else:
-                        is_dir = entry.is_dir()
-                except OSError:
-                    # If is_dir() raises an OSError, consider the entry not to
-                    # be a directory, same behaviour as os.path.isdir().
-                    is_dir = False
-
-                if is_dir:
-                    dirs.append(entry.name)
-                else:
-                    nondirs.append(entry.name)
-
-                if not topdown and is_dir:
-                    # Bottom-up: traverse into sub-directory, but exclude
-                    # symlinks to directories if followlinks is False
-                    if followlinks:
-                        walk_into = True
-                    else:
-                        try:
-                            is_symlink = entry.is_symlink()
-                        except OSError:
-                            # If is_symlink() raises an OSError, consider the
-                            # entry not to be a symbolic link, same behaviour
-                            # as os.path.islink().
-                            is_symlink = False
-                        walk_into = not is_symlink
-
-                    if walk_into:
-                        walk_dirs.append(entry.path)
-        if cont:
-            continue
-
         if topdown:
             # Yield before sub-directory traversal if going top down
             yield top, dirs, nondirs
@@ -774,7 +766,7 @@ def __ror__(self, other):
         new.update(self)
         return new
 
-def _createenviron():
+def _create_environ_mapping():
     if name == 'nt':
         # Where Env Var Names Must Be UPPERCASE
         def check_str(value):
@@ -804,9 +796,24 @@ def decode(value):
         encode, decode)
 
 # unicode environ
-environ = _createenviron()
-del _createenviron
+environ = _create_environ_mapping()
+del _create_environ_mapping
+
+
+if _exists("_create_environ"):
+    def reload_environ():
+        data = _create_environ()
+        if name == 'nt':
+            encodekey = environ.encodekey
+            data = {encodekey(key): value
+                    for key, value in data.items()}
+
+        # modify in-place to keep os.environb in sync
+        env_data = environ._data
+        env_data.clear()
+        env_data.update(data)
 
+    __all__.append("reload_environ")
 
 def getenv(key, default=None):
     """Get an environment variable, return None if it doesn't exist.

diff --git a/Lib/test/test_genericpath.py b/Lib/test/test_genericpath.py
@@ -170,7 +170,6 @@ def test_exists_fd(self):
             os.close(w)
         self.assertFalse(self.pathmodule.exists(r))
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
     def test_exists_bool(self):
         for fd in False, True:
             with self.assertWarnsRegex(RuntimeWarning,