#34294: File locking fails if argtypes redefined
----------------------------------------+------------------------
Reporter: Grub4K | Owner: nobody
Type: Bug | Status: new
Component: Core (Other) | Version: dev
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 1
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
----------------------------------------+------------------------
`django.core.files.locks` uses `ctypes.windll.kernel32` which is a global
instance. If other code redefines `windll.kernel32.LockFileEx.argtypes`
the function fails with an error.
I am not sure how to write a test since its global
{{{#!python
import ctypes
import ctypes.wintypes
from django.core.files import locks
class OVERLAPPED(ctypes.Structure):
_fields_ = [
("Internal", ctypes.wintypes.LPVOID),
("InternalHigh", ctypes.wintypes.LPVOID),
("Offset", ctypes.wintypes.DWORD),
("OffsetHigh", ctypes.wintypes.DWORD),
("hEvent", ctypes.wintypes.HANDLE),
]
ctypes.windll.kernel32.LockFileEx.argtypes = [
ctypes.wintypes.HANDLE,
ctypes.wintypes.DWORD,
ctypes.wintypes.DWORD,
ctypes.wintypes.DWORD,
ctypes.wintypes.DWORD,
ctypes.wintypes.DWORD,
]
with open("./file", "w") as f:
locks.lock(f, locks.LOCK_EX)
}}}
Possible patch:
{{{#!diff
diff --git a/django/core/files/locks.py b/django/core/files/locks.py
index 5752b08a69..c0f471f87d 100644
--- a/django/core/files/locks.py
+++ b/django/core/files/locks.py
@@ -32,12 +32,12 @@ if os.name == "nt":
POINTER,
Structure,
Union,
+ WinDLL,
byref,
c_int64,
c_ulong,
c_void_p,
sizeof,
- windll,
)
from ctypes.wintypes import BOOL, DWORD, HANDLE
@@ -73,10 +73,11 @@ if os.name == "nt":
LPOVERLAPPED = POINTER(OVERLAPPED)
# --- Define function prototypes for extra safety ---
- LockFileEx = windll.kernel32.LockFileEx
+ kernel32 = WinDLL("kernel32")
+ LockFileEx = kernel32.LockFileEx
LockFileEx.restype = BOOL
LockFileEx.argtypes = [HANDLE, DWORD, DWORD, DWORD, DWORD,
LPOVERLAPPED]
- UnlockFileEx = windll.kernel32.UnlockFileEx
+ UnlockFileEx = kernel32.UnlockFileEx
UnlockFileEx.restype = BOOL
UnlockFileEx.argtypes = [HANDLE, DWORD, DWORD, DWORD, LPOVERLAPPED]
diff --git a/tests/files/tests.py b/tests/files/tests.py
index b3478d2732..d0e633cb7a 100644
--- a/tests/files/tests.py
+++ b/tests/files/tests.py
@@ -200,6 +200,32 @@ class FileTests(unittest.TestCase):
self.assertIs(locks.unlock(f1), True)
self.assertIs(locks.unlock(f2), True)
+ @unittest.skipIf(os.name != "nt", "File locking usees WinDLL on
windows only")
+ def test_local_windll(self):
+ import ctypes
+ import ctypes.wintypes
+
+ old_argtypes = ctypes.windll.kernel32.LockFileEx.argtypes
+ try:
+ ctypes.windll.kernel32.LockFileEx.argtypes = [
+ ctypes.wintypes.HANDLE,
+ ctypes.wintypes.DWORD,
+ ctypes.wintypes.DWORD,
+ ctypes.wintypes.DWORD,
+ ctypes.wintypes.DWORD,
+ ctypes.wintypes.DWORD,
+ ]
+ file_path = Path(__file__).parent / "test.png"
+ with open(file_path) as file:
+ try:
+ locks.lock(file, locks.LOCK_EX)
+ except Exception:
+ self.fail("Locking raised exception with changed
argtypes")
+ else:
+ locks.unlock(file)
+ finally:
+ ctypes.windll.kernel32.LockFileEx.argtypes = old_argtypes
+
class NoNameFileTestCase(unittest.TestCase):
"""
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/34294>
Django <https://code.djangoproject.com/>
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