Fix #12084. os.stat on Windows wasn't working properly with relative symlinks.

briancurtin · briancurtin · commit d25aef55c8b0 · 2011-06-13T15:16:04.000-05:00
Use of DeviceIoControl to obtain the symlink path via the reparse tag was
removed. The code now uses GetFinalPathNameByHandle in the case of a
symbolic link and works properly given the added test which creates a symbolic
link and calls os.stat on it from multiple locations.

Victor Stinner also noticed an issue with os.lstat following the os.stat
code path when being passed bytes. The posix_lstat function was adjusted to
properly hook up win32_lstat instead of the previous STAT macro (win32_stat).
diff --git a/Lib/test/support.py b/Lib/test/support.py
@@ -1490,7 +1490,7 @@ def can_symlink():
     try:
         os.symlink(TESTFN, TESTFN + "can_symlink")
         can = True
-    except (OSError, NotImplementedError):
+    except (OSError, NotImplementedError, AttributeError):
         can = False
     _can_symlink = can
     return can
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
@@ -1243,6 +1243,51 @@ def check_stat(self, link, target):
         self.assertEqual(os.stat(link), os.stat(target))
         self.assertNotEqual(os.lstat(link), os.stat(link))
 
+        bytes_link = os.fsencode(link)
+        self.assertEqual(os.stat(bytes_link), os.stat(target))
+        self.assertNotEqual(os.lstat(bytes_link), os.stat(bytes_link))
+
+    def test_12084(self):
+        level1 = os.path.abspath(support.TESTFN)
+        level2 = os.path.join(level1, "level2")
+        level3 = os.path.join(level2, "level3")
+        try:
+            os.mkdir(level1)
+            os.mkdir(level2)
+            os.mkdir(level3)
+
+            file1 = os.path.abspath(os.path.join(level1, "file1"))
+
+            with open(file1, "w") as f:
+                f.write("file1")
+
+            orig_dir = os.getcwd()
+            try:
+                os.chdir(level2)
+                link = os.path.join(level2, "link")
+                os.symlink(os.path.relpath(file1), "link")
+                self.assertIn("link", os.listdir(os.getcwd()))
+
+                # Check os.stat calls from the same dir as the link
+                self.assertEqual(os.stat(file1), os.stat("link"))
+
+                # Check os.stat calls from a dir below the link
+                os.chdir(level1)
+                self.assertEqual(os.stat(file1),
+                                 os.stat(os.path.relpath(link)))
+
+                # Check os.stat calls from a dir above the link
+                os.chdir(level3)
+                self.assertEqual(os.stat(file1),
+                                 os.stat(os.path.relpath(link)))
+            finally:
+                os.chdir(orig_dir)
+        except OSError as err:
+            self.fail(err)
+        finally:
+            os.remove(file1)
+            shutil.rmtree(level1)
+
 
 class FSEncodingTests(unittest.TestCase):
     def test_nop(self):
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -10,6 +10,9 @@ What's New in Python 3.2.1 release candidate 2?
 Core and Builtins
 -----------------
 
+- Issue #12084: os.stat on Windows now works properly with relative symbolic
+  links when called from any directory.
+
 - Issue #1195: my_fgets() now always clears errors before calling fgets(). Fix
   the following case: sys.stdin.read() stopped with CTRL+d (end of file),
   raw_input() interrupted by CTRL+c.
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
