gh-117596: Fix realpath ValueError on null byte

Lib/posixpath.py

@@ -460,7 +460,7 @@ def realpath(filename, *, strict=False):
             if not stat.S_ISLNK(st.st_mode):
                 path = newpath
                 continue
-        except OSError:
+        except (OSError, ValueError):
             if strict:
                 raise
             path = newpath

Lib/test/test_posixpath.py

@@ -646,6 +646,15 @@ def test_realpath_resolve_first(self):
             safe_rmdir(ABSTFN + "/k")
             safe_rmdir(ABSTFN)
 
+    @skip_if_ABSTFN_contains_backslash
+    def test_realpath_null_byte(self):
+        path_with_null_byte = ABSTFN + "/\x00"
+        try:
+            os.mkdir(ABSTFN)
+            self.assertEqual(realpath(path_with_null_byte), path_with_null_byte)
+        finally:
+            safe_rmdir(ABSTFN)
+
     def test_relpath(self):
         (real_getcwd, os.getcwd) = (os.getcwd, lambda: r"/home/user/bar")
         try:

Misc/ACKS

@@ -773,6 +773,7 @@ Benjamin Hodgson
 Joerg-Cyril Hoehle
 Douwe Hoekstra
 Robert Hoelzl
+Stefan Hoelzl
 Gregor Hoffleit
 Chris Hoffman
 Tim Hoffmann

Misc/NEWS.d/next/Library/2024-04-07-06-46-43.gh-issue-117596.Mxo4gr.rst

@@ -0,0 +1 @@
+Fix :exc:`ValueError` when :func:`os.path.realpath` is called with a path containing a null byte. Patch by Stefan Hoelzl.