Read file with kernel32.dll (Python)

Question

I need to read file using kernel32.dll. I have read about CreateFile, SetFilePointer and ReadFile methods (I need to use them) - but not sure how to apply them.

As mentioned at msdn I need to specify all those arguments. I know that first is path to file, but have no idea what are those other arguments and in what way should I insert them.

Can anyone help me with "howto" on kernel32.dll CreateFile, SetFilePointer and ReadFile.

Really appreciate any help.

Update

The reason I try to use kernel32 is that I need really-really fast way to read from flash-drive. I need some way that will read directly from flash, without spending time in its file system. By this I mean direct access to required byte, without some long searches in file system.

Here is code I used for reading

    index = 524288
    data = open('Path-to-file', 'rb')
    while index < file_length:
        data.seek(index)
        headers.append((index, data.read(128)))
        index += cluster
    data.close()

This code takes about 8 minutes to look through 1 Gb file via USB.

I need it to be done at 4 minutes.

If someone has any suggestions how I can do it other way - I would really appreciate.

Update

I have tried win32file (pywin32) like this:

def get_headers(self):
    while self.index < self.file_len:
        handle = win32file.CreateFile(self.path, win32file.GENERIC_READ,
                                      win32file.FILE_SHARE_READ, None,
                                      win32file.OPEN_EXISTING,
                                      win32file.FILE_ATTRIBUTE_NORMAL, None)
        win32file.SetFilePointer(handle, self.index, win32file.FILE_CURRENT)
        header_ = win32file.ReadFile(handle, 128, None)
        header = header_[1]
        self.headers.append((self.index, header))
        self.index += cluster
        win32file.CloseHandle(handle)

It takes more time (12 minutes) than python "seek" and "read" functions. Does anyone know why usage of module for Windows dll increases time of reading?

Answer 1

Here's the most common use of CreateFile :

hFile = CreateFile("file.txt", GENERIC_READ, 0, 0, 3, 128, None)

And ReadFile :

ReadFile(hFile, pOutput, nNumberOfBytesToRead, lpNumberOfBytesRead, 0)

Note that, if you use ctypes , you'll need c_char_p (which represents a string) for pOutput (where the file content will be stored), and byref or pointer for lpNumberOfBytesRead .

You can also use pywin32 which I'm sure will be simpler.

Hope this helps.