From c190efe83828164aec928a21850192a05c669335 Mon Sep 17 00:00:00 2001
From: Nice Zombies <nineteendo19d0@gmail.com>
Date: Tue, 12 Nov 2024 22:18:03 +0100
Subject: [PATCH] gh-119826: Improved fallback for ntpath.abspath() on Windows
 (GH-119938) (cherry picked from commit
 4b00aba42e4d9440d22e399ec2122fe8601bbe54)

Co-authored-by: Nice Zombies <nineteendo19d0@gmail.com>
---
 Lib/ntpath.py                                 | 49 ++++++++++++-------
 Lib/test/test_ntpath.py                       |  3 ++
 ...-06-02-11-48-19.gh-issue-119826.N1obGa.rst |  1 +
 3 files changed, 35 insertions(+), 18 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2024-06-02-11-48-19.gh-issue-119826.N1obGa.rst

diff --git a/Lib/ntpath.py b/Lib/ntpath.py
index 2e290dcf9de9da..c05e965fcb91d1 100644
--- a/Lib/ntpath.py
+++ b/Lib/ntpath.py
@@ -561,28 +561,21 @@ def normpath(path):
         return prefix + sep.join(comps)
 
 
-def _abspath_fallback(path):
-    """Return the absolute version of a path as a fallback function in case
-    `nt._getfullpathname` is not available or raises OSError. See bpo-31047 for
-    more.
-
-    """
-
-    path = os.fspath(path)
-    if not isabs(path):
-        if isinstance(path, bytes):
-            cwd = os.getcwdb()
-        else:
-            cwd = os.getcwd()
-        path = join(cwd, path)
-    return normpath(path)
-
 # Return an absolute path.
 try:
     from nt import _getfullpathname
 
 except ImportError: # not running on Windows - mock up something sensible
-    abspath = _abspath_fallback
+    def abspath(path):
+        """Return the absolute version of a path."""
+        path = os.fspath(path)
+        if not isabs(path):
+            if isinstance(path, bytes):
+                cwd = os.getcwdb()
+            else:
+                cwd = os.getcwd()
+            path = join(cwd, path)
+        return normpath(path)
 
 else:  # use native Windows method on Windows
     def abspath(path):
@@ -590,7 +583,27 @@ def abspath(path):
         try:
             return _getfullpathname(normpath(path))
         except (OSError, ValueError):
-            return _abspath_fallback(path)
+            # See gh-75230, handle outside for cleaner traceback
+            pass
+        path = os.fspath(path)
+        if not isabs(path):
+            if isinstance(path, bytes):
+                sep = b'\\'
+                getcwd = os.getcwdb
+            else:
+                sep = '\\'
+                getcwd = os.getcwd
+            drive, root, path = splitroot(path)
+            # Either drive or root can be nonempty, but not both.
+            if drive or root:
+                try:
+                    path = join(_getfullpathname(drive + root), path)
+                except (OSError, ValueError):
+                    # Drive "\0:" cannot exist; use the root directory.
+                    path = drive + sep + path
+            else:
+                path = join(getcwd(), path)
+        return normpath(path)
 
 try:
     from nt import _getfinalpathname, readlink as _nt_readlink
diff --git a/Lib/test/test_ntpath.py b/Lib/test/test_ntpath.py
index 9c6715b2cc37b4..4924db983b568f 100644
--- a/Lib/test/test_ntpath.py
+++ b/Lib/test/test_ntpath.py
@@ -743,6 +743,9 @@ def test_abspath(self):
         tester('ntpath.abspath("C:\\spam. . .")', "C:\\spam")
         tester('ntpath.abspath("C:/nul")',  "\\\\.\\nul")
         tester('ntpath.abspath("C:\\nul")', "\\\\.\\nul")
+        self.assertTrue(ntpath.isabs(ntpath.abspath("C:spam")))
+        self.assertEqual(ntpath.abspath("C:\x00"), ntpath.join(ntpath.abspath("C:"), "\x00"))
+        self.assertEqual(ntpath.abspath("\x00:spam"), "\x00:\\spam")
         tester('ntpath.abspath("//..")',           "\\\\")
         tester('ntpath.abspath("//../")',          "\\\\..\\")
         tester('ntpath.abspath("//../..")',        "\\\\..\\")
diff --git a/Misc/NEWS.d/next/Library/2024-06-02-11-48-19.gh-issue-119826.N1obGa.rst b/Misc/NEWS.d/next/Library/2024-06-02-11-48-19.gh-issue-119826.N1obGa.rst
new file mode 100644
index 00000000000000..6901e7475dd082
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-06-02-11-48-19.gh-issue-119826.N1obGa.rst
@@ -0,0 +1 @@
+Always return an absolute path for :func:`os.path.abspath` on Windows.