[boost] [filesystem] revised function to determine available file system space

I'm planning to add a filesystem function to determine available disk space. Perhaps something like: struct space { boost::uintmax_t available; // bytes available to user boost::uintmax_t total; // total bytes on volume }; space filesystem_space( const path & p ); Comments? How safe is the assumption that uintmax_t is large enough nowadays for any modern compiler on a system supporting large disks. Better suggestions for the names? --Beman PS: this is slightly revised from a post on the users list.