Declaring variables at the beginning of such a small function is certainly not out of style. IMHO, it's not detrimental. In fact, I find it quite useful (i.e. just by reading the declarations, I can infer the expected flow of the function -- fd will be used to open a device file, from which ifr is going to be populated through a call to read() or an ioctl). However, it's largely a question of style.

Using strcpy is a big no-no -- it's both detrimental, and out of style. Its manpage gives this warning (on FreeBSD -- the one you'll get if you type man strcpy may differ, but all man pages have had a similar warning since 1990something):

> The strcpy() function is easily misused in a manner which enables malicious users to arbitrarily change a running program's functionality through a buffer overflow attack.

That's because strcpy(dst, src) will basically do something like this:

    int i = 0;
    while (src[i] != '\0') {
        dst[i] = src[i];
        i++;
    }

(the real implementation is usually more terse for reasons I won't go into right now, but this is what it basically does in more verbose terms).

without bothering to check if dst[i] is not beyond the end of dst. This allows you to write past the end of the buffer that holds dst, and who knows what's there...

Nowadays, all that usually happens (on sane operating systems running on machines with a MMU) is that your application crashes due to something called ASLR. It used to be a big problem before that, though, and it still is (on insane operating systems, on machines that don't have a MMU and so on).

Either way, it's not a good idea, and it's considered to be a pretty big code smell. strncpy is the encouraged version. strlcpy is the sane one, but it's not available on all platforms (and even when it is, it's not always sanely implemented).