Problem with ctypes and removing folder tree

programmer_2020 0
Viewed 23

I have a problem with very simple code.

from ctypes import CDLL
import shutil

# The random library ztrace_maps.dll copied from C:\Windows\SysWOW64 to C:/DLL/

class Test:
    def __init__(self):
        self.dll = CDLL("C:/DLL/ztrace_maps.dll")
    def __del__(self):
        del self.dll
        shutil.rmtree("C:/DLL/")

test = Test()
del test
shutil.rmtree("C:/DLL/")

I am not able to remove the catalog with dll during the execution of the Python script. The Python console (in Pycharm) is working fine. I found a workaround with the execution separate Python script after the closing of the script but should be another possibility to clean resources.

Error:

Traceback (most recent call last):
  File "C:/test.py", line 14, in <module>
    shutil.rmtree("C:/DLL/")
  File "C:\python32\python-3.8.10\Lib\shutil.py", line 740, in rmtree
    return _rmtree_unsafe(path, onerror)
  File "C:\python32\python-3.8.10\Lib\shutil.py", line 618, in _rmtree_unsafe
    onerror(os.unlink, fullname, sys.exc_info())
  File "C:\python32\python-3.8.10\Lib\shutil.py", line 616, in _rmtree_unsafe
    os.unlink(fullname)
PermissionError: [WinError 5] Access is denied: 'C:/DLL/ztrace_maps.dll'
Exception ignored in: <function Test.__del__ at 0x02F55EC8>
Traceback (most recent call last):
  File "C:/test.py", line 10, in __del__
  File "C:\python32\python-3.8.10\Lib\shutil.py", line 740, in rmtree
  File "C:\python32\python-3.8.10\Lib\shutil.py", line 618, in _rmtree_unsafe
  File "C:\python32\python-3.8.10\Lib\shutil.py", line 616, in _rmtree_unsafe
PermissionError: [WinError 5] Access is denied: 'C:/DLL/ztrace_maps.dll'

Process finished with exit code 1

I tested the other commands but with the same result.

ctypes shutil python
2 Answers

DLL files aren't unloaded instantly when deleted, (or maybe not unloaded ever), so deleting the reference to the library doesn't help.

instead you should look into how to unload a DLL (which is somewhat platform dependent) as found in this link.

Ahmed AEK0

Thank you Ahmed AEK! The solution with FreeLibrary is working correctly.

from ctypes import CDLL
import shutil
import ctypes

# random library ztrace_maps.dll from C:\Windows\SysWOW64
# copied to C:/DLL/

class Test:
    def __init__(self):
        self.dll = CDLL("C:/DLL/ztrace_maps.dll")
        self._handle = self.dll._handle

    def __del__(self):
        ctypes.windll.kernel32.FreeLibrary(self._handle)
        shutil.rmtree("C:/DLL/")

test = Test()
del test
programmer_20200
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