Moved symlink support into its own module. Ported can_symlink from Python 3.2, skipping symlink test when it cannot be invoked (such as when the symlink privilege is not present).

This commit is contained in:
Jason R. Coombs 2012-03-08 18:28:08 -05:00
parent ea4629afa6
commit e107ab3b6c
2 changed files with 105 additions and 76 deletions

100
Lib/test/symlink_support.py Normal file
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@ -0,0 +1,100 @@
import os
import unittest
import platform
from test.test_support import TESTFN
def can_symlink():
# cache the result in can_symlink.prev_val
prev_val = getattr(can_symlink, 'prev_val', None)
if prev_val is not None:
return prev_val
symlink_path = TESTFN + "can_symlink"
try:
symlink(TESTFN, symlink_path)
can = True
except (OSError, NotImplementedError, AttributeError):
can = False
else:
os.remove(symlink_path)
can_symlink.prev_val = can
return can
def skip_unless_symlink(test):
"""Skip decorator for tests that require functional symlink"""
ok = can_symlink()
msg = "Requires functional symlink implementation"
return test if ok else unittest.skip(msg)(test)
def _symlink_win32(target, link, target_is_directory=False):
"""
Ctypes symlink implementation since Python doesn't support
symlinks in windows yet. Borrowed from jaraco.windows project.
"""
import ctypes.wintypes
CreateSymbolicLink = ctypes.windll.kernel32.CreateSymbolicLinkW
CreateSymbolicLink.argtypes = (
ctypes.wintypes.LPWSTR,
ctypes.wintypes.LPWSTR,
ctypes.wintypes.DWORD,
)
CreateSymbolicLink.restype = ctypes.wintypes.BOOLEAN
def format_system_message(errno):
"""
Call FormatMessage with a system error number to retrieve
the descriptive error message.
"""
# first some flags used by FormatMessageW
ALLOCATE_BUFFER = 0x100
ARGUMENT_ARRAY = 0x2000
FROM_HMODULE = 0x800
FROM_STRING = 0x400
FROM_SYSTEM = 0x1000
IGNORE_INSERTS = 0x200
# Let FormatMessageW allocate the buffer (we'll free it below)
# Also, let it know we want a system error message.
flags = ALLOCATE_BUFFER | FROM_SYSTEM
source = None
message_id = errno
language_id = 0
result_buffer = ctypes.wintypes.LPWSTR()
buffer_size = 0
arguments = None
bytes = ctypes.windll.kernel32.FormatMessageW(
flags,
source,
message_id,
language_id,
ctypes.byref(result_buffer),
buffer_size,
arguments,
)
# note the following will cause an infinite loop if GetLastError
# repeatedly returns an error that cannot be formatted, although
# this should not happen.
handle_nonzero_success(bytes)
message = result_buffer.value
ctypes.windll.kernel32.LocalFree(result_buffer)
return message
def handle_nonzero_success(result):
if result == 0:
value = ctypes.windll.kernel32.GetLastError()
strerror = format_system_message(value)
raise WindowsError(value, strerror)
target_is_directory = target_is_directory or os.path.isdir(target)
handle_nonzero_success(CreateSymbolicLink(link, target, target_is_directory))
symlink = os.symlink if hasattr(os, 'symlink') else (
_symlink_win32 if platform.system() == 'Windows' else None
)
def remove_symlink(name):
# On Windows, to remove a directory symlink, one must use rmdir
try:
os.rmdir(name)
except OSError:
os.remove(name)

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@ -12,6 +12,7 @@ import shutil
from test.test_support import (unlink, TESTFN, unload, run_unittest, rmtree,
is_jython, check_warnings, EnvironmentVarGuard)
from test import symlink_support
from test import script_helper
def remove_files(name):
@ -497,11 +498,9 @@ class TestSymbolicallyLinkedPackage(unittest.TestCase):
if os.path.exists(self.tagged):
shutil.rmtree(self.tagged)
if os.path.exists(self.package_name):
self.remove_symlink(self.package_name)
symlink_support.remove_symlink(self.package_name)
self.orig_sys_path = sys.path[:]
symlink = getattr(os, 'symlink', None) or self._symlink_win32
# create a sample package; imagine you have a package with a tag and
# you want to symbolically link it from its untagged name.
os.mkdir(self.tagged)
@ -511,7 +510,7 @@ class TestSymbolicallyLinkedPackage(unittest.TestCase):
# now create a symlink to the tagged package
# sample -> sample-tagged
symlink(self.tagged, self.package_name)
symlink_support.symlink(self.tagged, self.package_name)
assert os.path.isdir(self.package_name)
assert os.path.isfile(os.path.join(self.package_name, '__init__.py'))
@ -520,74 +519,12 @@ class TestSymbolicallyLinkedPackage(unittest.TestCase):
def tagged(self):
return self.package_name + '-tagged'
@classmethod
def _symlink_win32(cls, target, link, target_is_directory=False):
"""
Ctypes symlink implementation since Python doesn't support
symlinks in windows yet. Borrowed from jaraco.windows project.
"""
import ctypes.wintypes
CreateSymbolicLink = ctypes.windll.kernel32.CreateSymbolicLinkW
CreateSymbolicLink.argtypes = (
ctypes.wintypes.LPWSTR,
ctypes.wintypes.LPWSTR,
ctypes.wintypes.DWORD,
)
CreateSymbolicLink.restype = ctypes.wintypes.BOOLEAN
def format_system_message(errno):
"""
Call FormatMessage with a system error number to retrieve
the descriptive error message.
"""
# first some flags used by FormatMessageW
ALLOCATE_BUFFER = 0x100
ARGUMENT_ARRAY = 0x2000
FROM_HMODULE = 0x800
FROM_STRING = 0x400
FROM_SYSTEM = 0x1000
IGNORE_INSERTS = 0x200
# Let FormatMessageW allocate the buffer (we'll free it below)
# Also, let it know we want a system error message.
flags = ALLOCATE_BUFFER | FROM_SYSTEM
source = None
message_id = errno
language_id = 0
result_buffer = ctypes.wintypes.LPWSTR()
buffer_size = 0
arguments = None
bytes = ctypes.windll.kernel32.FormatMessageW(
flags,
source,
message_id,
language_id,
ctypes.byref(result_buffer),
buffer_size,
arguments,
)
# note the following will cause an infinite loop if GetLastError
# repeatedly returns an error that cannot be formatted, although
# this should not happen.
handle_nonzero_success(bytes)
message = result_buffer.value
ctypes.windll.kernel32.LocalFree(result_buffer)
return message
def handle_nonzero_success(result):
if result == 0:
value = ctypes.windll.kernel32.GetLastError()
strerror = format_system_message(value)
raise WindowsError(value, strerror)
target_is_directory = target_is_directory or os.path.isdir(target)
handle_nonzero_success(CreateSymbolicLink(link, target, target_is_directory))
# regression test for issue6727
@unittest.skipUnless(
not hasattr(sys, 'getwindowsversion')
or sys.getwindowsversion() >= (6, 0),
"Windows Vista or later required")
@symlink_support.skip_unless_symlink
def test_symlinked_dir_importable(self):
# make sure sample can only be imported from the current directory.
sys.path[:] = ['.']
@ -598,19 +535,11 @@ class TestSymbolicallyLinkedPackage(unittest.TestCase):
def tearDown(self):
# now cleanup
if os.path.exists(self.package_name):
self.remove_symlink(self.package_name)
symlink_support.remove_symlink(self.package_name)
if os.path.exists(self.tagged):
shutil.rmtree(self.tagged)
sys.path[:] = self.orig_sys_path
@staticmethod
def remove_symlink(name):
# On Windows, to remove a directory symlink, one must use rmdir
try:
os.rmdir(name)
except OSError:
os.remove(name)
def test_main(verbose=None):
run_unittest(ImportTests, PycRewritingTests, PathsTests,
RelativeImportTests, TestSymbolicallyLinkedPackage)