Q. What about the attributes?
A. Make the attributes the same.
Q. Should I modify the attributes of the source file? If this file copy is part of a backup or archive operation, it'd probably be a mistake to leave the 'Archive' attribute on.
A. No, leave them as-is.
Q. What if the source file has the Archive attribute off? If I make it off on the new file as well, it could screw up the user's backup software.
A. Just make it the same. I don't care about the user's backup software.
Q. Well, I'm not sure that's the best approach to take when thinking about designing software FOR users, but if you say so.
Q. What about compression? It's a file attribute, but the copy destination may not support compression.
A. Don't compress the copy.
Q. Even if the source is compressed, and the destination supports compression?
Q. What about encryption? What if the source file is encrypted, but the destination does not support encryption?
A. Don't encrypt the copy if the destination doesn't support it.
Q. Mmmmm, sorry, don't mean to digress, but … that could be a serious security hole. Especially if wherever this file copy function ends up supports arbitrary parameters (directly or indirectly).
A. Look, just copy the damn file.
"How would you write a routine to copy a file" is just another interview riddle; it doesn't deserve a face value response. David's answers are even better-- they implode the question under its own weight.
The only rational answer to "how would you write a routine to copy a file?" is another question: why would any competent programmer ever write a file copy routine?
The last time I checked, moving mount Fuji wasn't a part of our business plan, either.
* With apologies to Al Jaffee.