Programming

Hello,

I found some code on line.
Is a python function that bring up an Internet interface, here the code:

Code:

        # Get existing device flags
        ifreq = struct.pack('16sh', 'wlan0', 0)
        flags = struct.unpack('16sh', fcntl.ioctl(sockfd, SIOCGIFFLAGS, ifreq))[1]

I'm starting reading something about it. I know that the struct.pack is needed for compatibility with C struct.
But why we pack the wlan0 exactly with 16 string and 1 short (and not 30s10h)?
In my case for example I get:
and
the final result unpacking everything is 4163.
Is it because from the fcntl.ioctl (in this case) I will expect to fill it with string and short?

Thanks

D

You need to check what structure takes/return the specific ioctl() you are evoking. See your Unix documentation.

On Linux, it seems to be the interface flag, see /usr/include/net/if.h, standard interface flag enum.

HTH,
Loïc