Is an atomic-rename possible in Mac VFS/HFS+?

Question

With support for ACLs in Mac OS X, there is a way to declare a file as writeable but non-deletable.

This poses a problem with atomic writes, since the current implementa

Answer 1

A viable alternative would seem to create the file in a temporary directory, then call exchangedata on both files. HFS exports the VOL_CAP_INT_EXCHANGEDATA attribute, so that should work. The relevant checks in vfs_syscalls.c indicate that only read and write permissions are necessary for the call to succeed.