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[3.7] bpo-29248: Fix os.readlink() on Windows (GH-5577) #5644

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Merged
miss-islington merged 1 commit into from
Feb 12, 2018
Merged

[3.7] bpo-29248: Fix os.readlink() on Windows (GH-5577) #5644

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15 changes: 15 additions & 0 deletions Lib/test/test_os.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2165,6 +2165,21 @@ def test_12084(self):
finally:
os.chdir(orig_dir)

@unittest.skipUnless(os.path.lexists(r'C:\Users\All Users')
and os.path.exists(r'C:\ProgramData'),
'Test directories not found')
def test_29248(self):
# os.symlink() calls CreateSymbolicLink, which creates
# the reparse data buffer with the print name stored
# first, so the offset is always 0. CreateSymbolicLink
# stores the "PrintName" DOS path (e.g. "C:\") first,
# with an offset of 0, followed by the "SubstituteName"
# NT path (e.g. "\??\C:\"). The "All Users" link, on
# the other hand, seems to have been created manually
# with an inverted order.
target = os.readlink(r'C:\Users\All Users')
self.assertTrue(os.path.samefile(target, r'C:\ProgramData'))


@unittest.skipUnless(sys.platform == "win32", "Win32 specific tests")
class Win32JunctionTests(unittest.TestCase):
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Windows/2018-02-07-17-50-48.bpo-29248.Xzwj-6.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Fix :func:`os.readlink` on Windows, which was mistakenly treating the
``PrintNameOffset`` field of the reparse data buffer as a number of
characters instead of bytes. Patch by Craig Holmquist and SSE4.
6 changes: 3 additions & 3 deletions Modules/posixmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -7439,11 +7439,11 @@ win_readlink(PyObject *self, PyObject *args, PyObject *kwargs)
"not a symbolic link");
return NULL;
}
print_name = rdb->SymbolicLinkReparseBuffer.PathBuffer +
rdb->SymbolicLinkReparseBuffer.PrintNameOffset;
print_name = (wchar_t *)((char*)rdb->SymbolicLinkReparseBuffer.PathBuffer +
rdb->SymbolicLinkReparseBuffer.PrintNameOffset);

result = PyUnicode_FromWideChar(print_name,
rdb->SymbolicLinkReparseBuffer.PrintNameLength/2);
rdb->SymbolicLinkReparseBuffer.PrintNameLength / sizeof(wchar_t));
return result;
}

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