On March 28, 2023 12:32:59 PM GMT+09:00, Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote: >Ok, just to play along - maybe you can make it slightly less >nonsensical by throwing O_PATH into the mix, and now an empty >directory file descriptor at least has *some* use. That's the case I was thinking of: create a directory, then use exclusively *at system calls, never anything path-based. (I was using "atomic" loosely; not concerned about races here, just convenience.) >Now your code would not only be specific to Linux, it would be >specific to some very new version of Linux, and do something >completely different on older versions. I'm extremely not concerned with depending on current Linux. But that said... >Because those older versions will do random things, ranging from >"always return an error" to "create a regular file - not a directory - >and then return an error anyway" and finally "create a regular file - >not a directory - and return that resulting fd". ... Right, open has the un-extendable semantics, hence O_TMPFILE. Fair enough. Nevermind then. As is often the case for multi-operation syscalls, I'm better off just using io_uring for a mkdir-then-open.
