[Python-checkins] cpython (3.2): Issue #13772: In os.symlink() under Windows, do not try to guess the link

Tue Jan 24 09:13:48 CET 2012

http://hg.python.org/cpython/rev/839fa289e226
changeset: 74589:839fa289e226
branch: 3.2
parent: 74582:a72ca8b23cdf
user: Antoine Pitrou <solipsis at pitrou.net>
date: Tue Jan 24 08:59:28 2012 +0100
summary:
 Issue #13772: In os.symlink() under Windows, do not try to guess the link
target's type (file or directory). The detection was buggy and made the
call non-atomic (therefore prone to race conditions).
files:
 Doc/library/os.rst | 9 +++------
 Lib/test/test_os.py | 9 +++++++--
 Misc/NEWS | 4 ++++
 Modules/posixmodule.c | 11 -----------
 4 files changed, 14 insertions(+), 19 deletions(-)

diff --git a/Doc/library/os.rst b/Doc/library/os.rst
--- a/Doc/library/os.rst
+++ b/Doc/library/os.rst
@@ -1429,11 +1429,9 @@
 *target_is_directory*, which defaults to ``False``.
 
 On Windows, a symlink represents a file or a directory, and does not morph to
- the target dynamically. For this reason, when creating a symlink on Windows,
- if the target is not already present, the symlink will default to being a
- file symlink. If *target_is_directory* is set to ``True``, the symlink will
- be created as a directory symlink. This parameter is ignored if the target
- exists (and the symlink is created with the same type as the target).
+ the target dynamically. If *target_is_directory* is set to ``True``, the
+ symlink will be created as a directory symlink, otherwise as a file symlink
+ (the default).
 
 Symbolic link support was introduced in Windows 6.0 (Vista). :func:`symlink`
 will raise a :exc:`NotImplementedError` on Windows versions earlier than 6.0.
@@ -1446,7 +1444,6 @@
 administrator level. Either obtaining the privilege or running your
 application as an administrator are ways to successfully create symlinks.
 
-
 :exc:`OSError` is raised when the function is called by an unprivileged
 user.
 
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -476,7 +476,12 @@
 f.write("I'm " + path + " and proud of it. Blame test_os.\n")
 f.close()
 if support.can_symlink():
- os.symlink(os.path.abspath(t2_path), link_path)
+ if os.name == 'nt':
+ def symlink_to_dir(src, dest):
+ os.symlink(src, dest, True)
+ else:
+ symlink_to_dir = os.symlink
+ symlink_to_dir(os.path.abspath(t2_path), link_path)
 sub2_tree = (sub2_path, ["link"], ["tmp3"])
 else:
 sub2_tree = (sub2_path, [], ["tmp3"])
@@ -1106,7 +1111,7 @@
 os.remove(self.missing_link)
 
 def test_directory_link(self):
- os.symlink(self.dirlink_target, self.dirlink)
+ os.symlink(self.dirlink_target, self.dirlink, True)
 self.assertTrue(os.path.exists(self.dirlink))
 self.assertTrue(os.path.isdir(self.dirlink))
 self.assertTrue(os.path.islink(self.dirlink))
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -108,6 +108,10 @@
 Library
 -------
 
+- Issue #13772: In os.symlink() under Windows, do not try to guess the link
+ target's type (file or directory). The detection was buggy and made the
+ call non-atomic (therefore prone to race conditions).
+
 - Issue #6631: Disallow relative file paths in urllib urlopen methods.
 
 - Issue #13722: Avoid silencing ImportErrors when initializing the codecs
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -5330,7 +5330,6 @@
 PyObject *src, *dest;
 int target_is_directory = 0;
 DWORD res;
- WIN32_FILE_ATTRIBUTE_DATA src_info;
 
 if (!check_CreateSymbolicLinkW())
 {
@@ -5351,16 +5350,6 @@
 return NULL;
 }
 
- /* if src is a directory, ensure target_is_directory==1 */
- if(
- GetFileAttributesExW(
- PyUnicode_AsUnicode(src), GetFileExInfoStandard, &src_info
- ))
- {
- target_is_directory = target_is_directory ||
- (src_info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY);
- }
-
 Py_BEGIN_ALLOW_THREADS
 res = Py_CreateSymbolicLinkW(
 PyUnicode_AsUnicode(dest),
-- 
Repository URL: http://hg.python.org/cpython
