From 4cc576fafdcb4a4485667da5ced79b407bc5b93d Mon Sep 17 00:00:00 2001
From: Barney Gale <barney.gale@gmail.com>
Date: Fri, 8 Nov 2024 16:47:51 +0000
Subject: [PATCH] GH-126212: Fix removal of slashes in file URIs on Windows
 (GH-126214)

Adjust `urllib.request.pathname2url()` and `url2pathname()` so that they
don't remove slashes from Windows DOS drive paths and URLs. There was no
basis for this behaviour, and it conflicts with how UNC and POSIX paths are
handled.
(cherry picked from commit 54c63a32d06cb5f07a66245c375eac7d7efb964a)

Co-authored-by: Barney Gale <barney.gale@gmail.com>
---
 Lib/nturl2path.py                             | 25 +++++--------------
 Lib/test/test_urllib.py                       | 11 ++++++--
 ...-10-30-23-59-36.gh-issue-126212._9uYjT.rst |  3 +++
 3 files changed, 18 insertions(+), 21 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2024-10-30-23-59-36.gh-issue-126212._9uYjT.rst

diff --git a/Lib/nturl2path.py b/Lib/nturl2path.py
index 6453f202c26d14..2f9fec7893afd1 100644
--- a/Lib/nturl2path.py
+++ b/Lib/nturl2path.py
@@ -24,23 +24,15 @@ def url2pathname(url):
             # convert this to \\host\path\on\remote\host
             # (notice halving of slashes at the start of the path)
             url = url[2:]
-        components = url.split('/')
         # make sure not to convert quoted slashes :-)
-        return urllib.parse.unquote('\\'.join(components))
+        return urllib.parse.unquote(url.replace('/', '\\'))
     comp = url.split('|')
     if len(comp) != 2 or comp[0][-1] not in string.ascii_letters:
         error = 'Bad URL: ' + url
         raise OSError(error)
     drive = comp[0][-1].upper()
-    components = comp[1].split('/')
-    path = drive + ':'
-    for comp in components:
-        if comp:
-            path = path + '\\' + urllib.parse.unquote(comp)
-    # Issue #11474 - handing url such as |c/|
-    if path.endswith(':') and url.endswith('/'):
-        path += '\\'
-    return path
+    tail = urllib.parse.unquote(comp[1].replace('/', '\\'))
+    return drive + ':' + tail
 
 def pathname2url(p):
     """OS-specific conversion from a file system path to a relative URL
@@ -60,17 +52,12 @@ def pathname2url(p):
             raise OSError('Bad path: ' + p)
     if not ':' in p:
         # No drive specifier, just convert slashes and quote the name
-        components = p.split('\\')
-        return urllib.parse.quote('/'.join(components))
+        return urllib.parse.quote(p.replace('\\', '/'))
     comp = p.split(':', maxsplit=2)
     if len(comp) != 2 or len(comp[0]) > 1:
         error = 'Bad path: ' + p
         raise OSError(error)
 
     drive = urllib.parse.quote(comp[0].upper())
-    components = comp[1].split('\\')
-    path = '///' + drive + ':'
-    for comp in components:
-        if comp:
-            path = path + '/' + urllib.parse.quote(comp)
-    return path
+    tail = urllib.parse.quote(comp[1].replace('\\', '/'))
+    return '///' + drive + ':' + tail
diff --git a/Lib/test/test_urllib.py b/Lib/test/test_urllib.py
index 0e1b13d31c9273..2b59fb617cbdda 100644
--- a/Lib/test/test_urllib.py
+++ b/Lib/test/test_urllib.py
@@ -1535,8 +1535,10 @@ def test_pathname2url_win(self):
         self.assertEqual(fn('\\\\?\\C:\\dir'), '///C:/dir')
         self.assertEqual(fn('\\\\?\\unc\\server\\share\\dir'), '//server/share/dir')
         self.assertEqual(fn("C:"), '///C:')
-        self.assertEqual(fn("C:\\"), '///C:')
+        self.assertEqual(fn("C:\\"), '///C:/')
         self.assertEqual(fn('C:\\a\\b.c'), '///C:/a/b.c')
+        self.assertEqual(fn('C:\\a\\b.c\\'), '///C:/a/b.c/')
+        self.assertEqual(fn('C:\\a\\\\b.c'), '///C:/a//b.c')
         self.assertEqual(fn('C:\\a\\b%#c'), '///C:/a/b%25%23c')
         self.assertEqual(fn('C:\\a\\b\xe9'), '///C:/a/b%C3%A9')
         self.assertEqual(fn('C:\\foo\\bar\\spam.foo'), "///C:/foo/bar/spam.foo")
@@ -1572,13 +1574,15 @@ def test_url2pathname_win(self):
         self.assertEqual(fn("///C|"), 'C:')
         self.assertEqual(fn("///C:"), 'C:')
         self.assertEqual(fn('///C:/'), 'C:\\')
-        self.assertEqual(fn('/C|//'), 'C:\\')
+        self.assertEqual(fn('/C|//'), 'C:\\\\')
         self.assertEqual(fn('///C|/path'), 'C:\\path')
         # No DOS drive
         self.assertEqual(fn("///C/test/"), '\\\\\\C\\test\\')
         self.assertEqual(fn("////C/test/"), '\\\\C\\test\\')
         # DOS drive paths
         self.assertEqual(fn('C:/path/to/file'), 'C:\\path\\to\\file')
+        self.assertEqual(fn('C:/path/to/file/'), 'C:\\path\\to\\file\\')
+        self.assertEqual(fn('C:/path/to//file'), 'C:\\path\\to\\\\file')
         self.assertEqual(fn('C|/path/to/file'), 'C:\\path\\to\\file')
         self.assertEqual(fn('/C|/path/to/file'), 'C:\\path\\to\\file')
         self.assertEqual(fn('///C|/path/to/file'), 'C:\\path\\to\\file')
@@ -1592,6 +1596,9 @@ def test_url2pathname_win(self):
         # Localhost paths
         self.assertEqual(fn('//localhost/C:/path/to/file'), 'C:\\path\\to\\file')
         self.assertEqual(fn('//localhost/C|/path/to/file'), 'C:\\path\\to\\file')
+        # Percent-encoded forward slashes are preserved for backwards compatibility
+        self.assertEqual(fn('C:/foo%2fbar'), 'C:\\foo/bar')
+        self.assertEqual(fn('//server/share/foo%2fbar'), '\\\\server\\share\\foo/bar')
         # Round-tripping
         paths = ['C:',
                  r'\\\C\test\\',
diff --git a/Misc/NEWS.d/next/Library/2024-10-30-23-59-36.gh-issue-126212._9uYjT.rst b/Misc/NEWS.d/next/Library/2024-10-30-23-59-36.gh-issue-126212._9uYjT.rst
new file mode 100644
index 00000000000000..047fe0f68048b5
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-10-30-23-59-36.gh-issue-126212._9uYjT.rst
@@ -0,0 +1,3 @@
+Fix issue where :func:`urllib.request.pathname2url` and
+:func:`~urllib.request.url2pathname` removed slashes from Windows DOS drive
+paths and URLs.