[$] Reconsidering O_CREAT|O_DIRECTORY

Linux provides a system call (mkdir())to create a directory, and a few variants ofopen() that can open a directory. There is, however, nosystem call in Linux that can create and open a directory in a single,race-free call. Jori Koolstra has been working on remedying thatsituation, most recently by repurposing a set of open() flags that currentlyreturn an error. There are, however, concerns that show just how hard itcan be to create user-space interfaces that do not present traps forapplication developers.