在Python中，如何传递ctypes文件描述符来打开文件？

Question

我正在尝试复制与On Windows, how to open for writing a file already opened for writing by another process?中相似的内容 所以我按照Piotr Dobrogost的回答，修改Using a struct as a function argument with the python ctypes module中的代码，根据我的目的更改标志和属性（从这里https://msdn.microsoft.com/en-us/library/windows/desktop/aa363858(v=vs.85).aspx和这里http://unix.superglobalmegacorp.com/Net2/newsrc/sys/fcntl.h.html）并添加Python（使用3.3版本）open函数： 从os导入路径 从ctypes导入* 从ctypes.wintypes进口*

GENERIC_READ = 0x80000000
GENERIC_WRITE = 0x40000000

FILE_SHARE_DELETE = 0x00000004
FILE_SHARE_READ = 0x00000001
FILE_SHARE_WRITE = 0x00000002
FILE_SHARE_READ_WRITE = (FILE_SHARE_READ | FILE_SHARE_WRITE)

OPEN_EXISTING = 3

FILE_ATTRIBUTE_NORMAL = 128
FILE_ATTRIBUTE_TEMPORARY = 256

O_RDONLY =  0x0000      # open for reading only 
O_WRONLY = 0x0001       # open for writing only 
O_RDWR = 0x0002     # open for reading and writing 
O_ACCMODE = 0x0003      # mask for above modes 
O_append = 0x0008       # set append mode 

INVALID_HANDLE_VALUE = -1
LPOVERLAPPED = c_void_p
LPSECURITY_ATTRIBUTES = c_void_p

NULL = 0
FALSE = BOOL(0)
TRUE = BOOL(1)

def CreateFile(filename, access, sharemode, creation, flags):
    return HANDLE(windll.kernel32.CreateFileW(
        LPWSTR(filename),
        DWORD(access),
        DWORD(sharemode),
        LPSECURITY_ATTRIBUTES(NULL),
        DWORD(creation),
        DWORD(flags),
        HANDLE(NULL)
    ))


def translate_path(fpath):
    fpath = path.abspath(fpath)
    if fpath[len(fpath)-1] == '\\' and fpath[len(fpath)-2] == ':':
        fpath = fpath[:len(fpath)-1]
    return '\\??\\%s' % fpath

link_name = 'G:\\MATLAB\\Chronos_Python\\test.txt'
link_name = path.abspath(link_name)

hFile = CreateFile(link_name, GENERIC_READ, FILE_SHARE_WRITE, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL)

if hFile == HANDLE(INVALID_HANDLE_VALUE):
   raise Exception('Failed to open directory for junction creation.')

cFile = ctypes.cdll.msvcrt._open_osfhandle(hFile,O_RDONLY)
pyFile = open(cFile,'r')
pyFile.read()
pyFile.close()
ctypes.cdll.msvcrt._close(cFile)

windll.kernel32.CloseHandle(hFile)

但是在pyFile = open(cFile,'r')我得到了

OSError: [Errno 9] Bad file descriptor

这可能是非常基本的东西，因为我是python的新手。。。 如果有人能帮我修好它，我将不胜感激。在

Answer 1

假设文件的句柄是正确生成的，我想您的问题可能是：

pyFile = open(cFile,'r')

您正试图打开一个C运行时文件描述符，因此需要使用python中的fdopen函数：

^{pr2}$

您可能需要查看这里的文档—python通过Windows上的标准库公开了一些msvcrt函数： https://docs.python.org/3.6/library/msvcrt.html#msvcrt.open_osfhandle