Python socket (Socket Error Bad File Descriptor)

Question

The following receiveFile() function reads a filename and file data from the socket and splits it using the delimiter $.

But I am unable to close the socket and a Bad file descriptor error is raised. If I comment out the self.server_socket.close() statement then there is no error but the socket is listening forever.

Code:-

def listen(self):
    self.server_socket.listen(10)
    while True:
        client_socket, address = self.server_socket.accept()
        print 'connected to', address
        self.receiveFile(client_socket)



def receiveFile(self,sock):
    data = sock.recv(1024)
    data = data.split("$");
    print 'filename', data[0]
    f = open(data[0], "wb")
    #data = sock.recv(1024)
    print 'the data is', data[1]
    f.write(data[1])
    data = sock.recv(1024)
    while (data):
        f.write(data)
        data=sock.recv(1024)
    f.close()
    self.server_socket.close()
    print 'the data is', data
    print "File Downloaded"

Traceback:-

Traceback (most recent call last):
  File "server.py", line 45, in <module>
    a = Server(1111)
  File "server.py", line 15, in __init__
    self.listen()
  File "server.py", line 20, in listen
    client_socket, address = self.server_socket.accept()
  File "c:\Python27\lib\socket.py", line 202, in accept
    sock, addr = self._sock.accept()
  File "c:\Python27\lib\socket.py", line 170, in _dummy
    raise error(EBADF, 'Bad file descriptor')
socket.error: [Errno 9] Bad file descriptor

The error is probably not from that code, but wherever you're calling self.server_socket.accept() - would help to include a bit more of the code, and the full traceback. — Aya
– Aya, Commented May 5, 2013 at 8:58
So, is the idea you want the server to shut down once it's received a file, or do you just want to close the active connection? — Aya
– Aya, Commented May 5, 2013 at 9:06
@aya in this code i am trying to shut down the server once file is received. — Ali Ahmad
– Ali Ahmad, Commented May 5, 2013 at 9:17

Nickolay Olshevsky · Accepted Answer · 2013-05-05 09:16:45Z

14

You are closing the server's listening socket, and after that calling again accept() on it. To finish receiving one file you should close client connection's socket (sock in function receiveFile).

answered May 5, 2013 at 9:16

Nickolay Olshevsky

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2 Comments

Ali Ahmad Over a year ago

i understand your point, whats a proper sequence of closing the socket and shutdown the server

Nickolay Olshevsky Over a year ago

It depends on when do you need to shutdown server. If you want to receive only one file, just close client connection and after that - listening socket.

Aya · Accepted Answer · 2013-05-05 09:20:57Z

5

in this code i am trying to shut down the server once file is received

What you'll need is something to break out of the while True loop when you want to shut down the server. A simple solution would be to exploit the exception generated when you close the server socket...

def listen(self):
    self.server_socket.listen(10)
    while True:
        try:
            client_socket, address = self.server_socket.accept()
        except socket.error:
            break
        print 'connected to', address
        self.receiveFile(client_socket)
    print 'shutting down'

answered May 5, 2013 at 9:20

Aya

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1 Comment

Ali Ahmad Over a year ago

Thanks @aya i work around in a different way by returning value from from receiveFile function to break the loop

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