If you read it into memory and write it out, it could fail in tight memory situations.

I'm looking for something like copyfile(const char* from, const char* to) or copyfile(path from, path to), preferably something in Boost if it has it.  If you find it for me, it's more likely I'll get to implementing it.

We require Boost for JSON and a dozen things replacing dependencies on wxWidgets.  Boost is good, portable stuff, we should not shy away from it.