safe vs. unsafe foreign imports

Hi,

I'm a bit surprised that various I/O (in the filesystem sense, not Haskell `IO`) functions are imported as `unsafe`. While they won't call back to Haskell, depeding on which filesystem they talk to, they can take arbitrary amounts of time, blocking an execution context for this entire duration.

Would it make sense to also have "safe" version of the functions, for the case when performance is less of an issue compared to safety? Would it make sense to at least document that they are imported unsafe?

For the record, I've run a simple benchmark comparing "chmod" performance on various local and remote filesystems and the difference between unsafe and safe is between 10% slower (nfs) to 25% slower (local real filesystems) to 30% (tmpfs). So there is a performance hit indeed.