Post #1887729

@swick I've long thought that there's a hole that needs filling, that does what the original #Unix namei does but allows application mode code to supply everything necessary as (opaque) open descriptors: the root directory, the working directory, and the security credentials. Frustratingly, Unix openat(), Windows NT's NtCreateFile(), and #Hurd's dir_lookup() all come close but all miss a final piece of the puzzle in different ways. openat() misses, for example, a descriptor for the root directory and something like NT's process token handles for security processing. NT has odd ideas about current directories. This way, server processes could simply make use of the kernel's own already existing logic to handle not traversing '..' over a changed root, following symbolic links, and checking security using client credentials. There's so much reinvention of this wheel that would have been resolved decades ago if it had only been exposed as a system call. #filesystems