`OSError: [Errno 9] Bad file descriptor` with socket wrapper on Windows

Question

I was writing a wrapper class for sockets so I could use it as a file-like object for piping into the stdin and stdout of a process created with subprocess.Popen() .

def do_task():
    global s #The socket
    class sockIO():
        def __init__(self, s):self.s=s
        def write(self, m): self.s.send(m)
        def read(self, n=None): return self.s.read() if n is None else self.s.read(n)
        def fileno(self): return self.s.fileno()
    #stdio=s.makefile('rw')
    stdio=sockIO(s)
    cmd = subprocess.Popen('cmd', shell=True,
                           stdout=stdio, stderr=stdio,
                           stdin=stdio)

I didn't use socket.makefile() as it gives a io.UnsupportedOperation: fileno error, but with my present code I'm getting the following error on Windows (works fine on Linux):

Traceback (most recent call last):
  File "C:\Users\admin\Desktop\Projects\Python3\client.py", line 65, in <module>
    main()
  File "C:\Users\admin\Desktop\Projects\Python3\client.py", line 62, in main
    receive_commands2()
  File "C:\Users\admin\Desktop\Projects\Python3\client.py", line 57, in receive_commands2
    stdin=stdio)
  File "C:\Python3\lib\subprocess.py", line 914, in __init__
    errread, errwrite) = self._get_handles(stdin, stdout, stderr)
  File "C:\Python3\lib\subprocess.py", line 1127, in _get_handles
    p2cread = msvcrt.get_osfhandle(stdin.fileno())
OSError: [Errno 9] Bad file descriptor

Answer 1

According to the Python documentation about socket.fileno() , it is stated that this won't work in Windows. Quoting from Python Documentation :

socket.fileno()

Return the socket's file descriptor (a small integer). This is useful with select.select().

Under Windows the small integer returned by this method cannot be used where a file descriptor can be used (such as os.fdopen() ) . Unix does not have this limitation.

Note:

The above code will work in Linux and other *nix systems.