Strange Python error on Windows running under debugger

Question

The following code unexpectedly raises an exception:, pywintypes.error: (6, 'GetFileInformationByHandle', 'The handle is invalid.')i.e. GetFileInformationByHandledoes not work.

It is strange that everything works fine with the Python debugger . Even stranger is that when I delete some_parameteror GetFileInformationByHandle, the error disappears. This tells me that maybe this is some kind of memory error, but I'm really at a loss.

Some of the code may not be necessary, but I can no longer compress the code without causing an exception.

I tested this on Python 3.4.1 x64 on Windows 7, pywin32 218.5 and 219.

import os
import win32file
import pywintypes
from ctypes import *
from ctypes.wintypes import *


class BY_HANDLE_FILE_INFORMATION(Structure):
    _fields_ = [
        ('dwFileAttributes', DWORD),
        ('ftCreationTime', FILETIME),
        ('ftLastAccessTime', FILETIME),
        ('ftLastWriteTime', FILETIME),
        ('dwVolumeSerialNumber', DWORD),
        ('nFileSizeHigh', DWORD),
        ('nFileSizeLow', DWORD),
        ('nNumberOfLinks', DWORD),
        ('nFileIndexHigh', DWORD),
        ('nFileIndexLow', DWORD),
    ]


def GetFileInformationByHandle2(handle):
    GetFileInformationByHandle(handle)


def GetFileInformationByHandle(handle):
    bhfi = BY_HANDLE_FILE_INFORMATION()
    res = windll.kernelbase.GetFileInformationByHandle(handle.handle, byref(bhfi))
    if res == 0:
        errno = GetLastError()
        raise pywintypes.error(errno, 'GetFileInformationByHandle', FormatError(errno))


def open_file(path, param_1=False):
    return win32file.CreateFile(path, win32file.GENERIC_READ, 0, None, win32file.OPEN_EXISTING, 0, None)


def main():
    path = 'test.bin'
    open(path, 'wb').close()
    h_file = open_file(path)
    GetFileInformationByHandle(h_file)
    win32file.CloseHandle(h_file)
    h_file = open_file(path)
    GetFileInformationByHandle2(h_file)
    win32file.CloseHandle(h_file)
    os.remove(path)


if __name__ == '__main__':
    main()

Answer 1

It took me a lot of effort to figure out the reason.

, windll.kernelbase.GetFileInformationByHandle first handle DWORD QWORD. , , , 4 rcx, x64.

, , - .