gh-78997: AttributeError if loading fails in LibraryLoader.__getattr__

Co-authored-by: Zachary Ware <zachary.ware@gmail.com>
Co-authored-by: Filipe Laíns <filipe.lains@gmail.com>
Co-authored-by: Eric Wieser <wieser.eric@gmail.com>
This commit is contained in:
Ateeq Sharfuddin 2022-12-15 17:59:37 -05:00 committed by GitHub
parent b430399d41
commit 101cfe679f
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3 changed files with 195 additions and 1 deletions

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@ -444,7 +444,10 @@ class LibraryLoader(object):
def __getattr__(self, name):
if name[0] == '_':
raise AttributeError(name)
try:
dll = self._dlltype(name)
except OSError:
raise AttributeError(name)
setattr(self, name, dll)
return dll

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@ -0,0 +1,188 @@
from ctypes import *
import os
import shutil
import subprocess
import sys
import unittest
import test.support
from test.support import import_helper
from test.support import os_helper
from ctypes.util import find_library
libc_name = None
def setUpModule():
global libc_name
if os.name == "nt":
libc_name = find_library("c")
elif sys.platform == "cygwin":
libc_name = "cygwin1.dll"
else:
libc_name = find_library("c")
if test.support.verbose:
print("libc_name is", libc_name)
class LoaderTest(unittest.TestCase):
unknowndll = "xxrandomnamexx"
def test_load(self):
if libc_name is None:
self.skipTest('could not find libc')
CDLL(libc_name)
CDLL(os.path.basename(libc_name))
self.assertRaises(OSError, CDLL, self.unknowndll)
def test_load_version(self):
if libc_name is None:
self.skipTest('could not find libc')
if os.path.basename(libc_name) != 'libc.so.6':
self.skipTest('wrong libc path for test')
cdll.LoadLibrary("libc.so.6")
# linux uses version, libc 9 should not exist
self.assertRaises(OSError, cdll.LoadLibrary, "libc.so.9")
self.assertRaises(OSError, cdll.LoadLibrary, self.unknowndll)
def test_find(self):
for name in ("c", "m"):
lib = find_library(name)
if lib:
cdll.LoadLibrary(lib)
CDLL(lib)
@unittest.skipUnless(os.name == "nt",
'test specific to Windows')
def test_load_library(self):
# CRT is no longer directly loadable. See issue23606 for the
# discussion about alternative approaches.
#self.assertIsNotNone(libc_name)
if test.support.verbose:
print(find_library("kernel32"))
print(find_library("user32"))
if os.name == "nt":
windll.kernel32.GetModuleHandleW
windll["kernel32"].GetModuleHandleW
windll.LoadLibrary("kernel32").GetModuleHandleW
WinDLL("kernel32").GetModuleHandleW
# embedded null character
self.assertRaises(ValueError, windll.LoadLibrary, "kernel32\0")
@unittest.skipUnless(os.name == "nt",
'test specific to Windows')
def test_load_ordinal_functions(self):
import _ctypes_test
dll = WinDLL(_ctypes_test.__file__)
# We load the same function both via ordinal and name
func_ord = dll[2]
func_name = dll.GetString
# addressof gets the address where the function pointer is stored
a_ord = addressof(func_ord)
a_name = addressof(func_name)
f_ord_addr = c_void_p.from_address(a_ord).value
f_name_addr = c_void_p.from_address(a_name).value
self.assertEqual(hex(f_ord_addr), hex(f_name_addr))
self.assertRaises(AttributeError, dll.__getitem__, 1234)
@unittest.skipUnless(os.name == "nt", 'Windows-specific test')
def test_1703286_A(self):
from _ctypes import LoadLibrary, FreeLibrary
# On winXP 64-bit, advapi32 loads at an address that does
# NOT fit into a 32-bit integer. FreeLibrary must be able
# to accept this address.
# These are tests for https://www.python.org/sf/1703286
handle = LoadLibrary("advapi32")
FreeLibrary(handle)
@unittest.skipUnless(os.name == "nt", 'Windows-specific test')
def test_1703286_B(self):
# Since on winXP 64-bit advapi32 loads like described
# above, the (arbitrarily selected) CloseEventLog function
# also has a high address. 'call_function' should accept
# addresses so large.
from _ctypes import call_function
advapi32 = windll.advapi32
# Calling CloseEventLog with a NULL argument should fail,
# but the call should not segfault or so.
self.assertEqual(0, advapi32.CloseEventLog(None))
windll.kernel32.GetProcAddress.argtypes = c_void_p, c_char_p
windll.kernel32.GetProcAddress.restype = c_void_p
proc = windll.kernel32.GetProcAddress(advapi32._handle,
b"CloseEventLog")
self.assertTrue(proc)
# This is the real test: call the function via 'call_function'
self.assertEqual(0, call_function(proc, (None,)))
@unittest.skipUnless(os.name == "nt",
'test specific to Windows')
def test_load_hasattr(self):
# bpo-34816: shouldn't raise OSError
self.assertFalse(hasattr(windll, 'test'))
@unittest.skipUnless(os.name == "nt",
'test specific to Windows')
def test_load_dll_with_flags(self):
_sqlite3 = import_helper.import_module("_sqlite3")
src = _sqlite3.__file__
if src.lower().endswith("_d.pyd"):
ext = "_d.dll"
else:
ext = ".dll"
with os_helper.temp_dir() as tmp:
# We copy two files and load _sqlite3.dll (formerly .pyd),
# which has a dependency on sqlite3.dll. Then we test
# loading it in subprocesses to avoid it starting in memory
# for each test.
target = os.path.join(tmp, "_sqlite3.dll")
shutil.copy(src, target)
shutil.copy(os.path.join(os.path.dirname(src), "sqlite3" + ext),
os.path.join(tmp, "sqlite3" + ext))
def should_pass(command):
with self.subTest(command):
subprocess.check_output(
[sys.executable, "-c",
"from ctypes import *; import nt;" + command],
cwd=tmp
)
def should_fail(command):
with self.subTest(command):
with self.assertRaises(subprocess.CalledProcessError):
subprocess.check_output(
[sys.executable, "-c",
"from ctypes import *; import nt;" + command],
cwd=tmp, stderr=subprocess.STDOUT,
)
# Default load should not find this in CWD
should_fail("WinDLL('_sqlite3.dll')")
# Relative path (but not just filename) should succeed
should_pass("WinDLL('./_sqlite3.dll')")
# Insecure load flags should succeed
# Clear the DLL directory to avoid safe search settings propagating
should_pass("windll.kernel32.SetDllDirectoryW(None); WinDLL('_sqlite3.dll', winmode=0)")
# Full path load without DLL_LOAD_DIR shouldn't find dependency
should_fail("WinDLL(nt._getfullpathname('_sqlite3.dll'), " +
"winmode=nt._LOAD_LIBRARY_SEARCH_SYSTEM32)")
# Full path load with DLL_LOAD_DIR should succeed
should_pass("WinDLL(nt._getfullpathname('_sqlite3.dll'), " +
"winmode=nt._LOAD_LIBRARY_SEARCH_SYSTEM32|" +
"nt._LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR)")
# User-specified directory should succeed
should_pass("import os; p = os.add_dll_directory(os.getcwd());" +
"WinDLL('_sqlite3.dll'); p.close()")
if __name__ == "__main__":
unittest.main()

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@ -0,0 +1,3 @@
``hasattr(ctypes.windll, 'nonexistant')`` now returns ``False`` instead of raising :exc:`OSError`.