On 2020-03-01, Aleksa Sarai wrote: > On 2020-02-28, Christian Brauner wrote: > > So we either end up adding new AT_* flags mirroring the new RESOLVE_* > > flags or we end up adding new RESOLVE_* flags mirroring parts of AT_* > > flags. And if that's a possibility I vote for RESOLVE_* flags going > > forward. The have better naming too imho. > > I can see the argument for merging AT_ flags into RESOLVE_ flags (fewer > flag arguments for syscalls is usually a good thing) ... but I don't > really like it. There are a couple of problems right off the bat: > > * The prefix RESOLVE_ implies that the flag is specifically about path > resolution. While you could argue that AT_EMPTY_PATH is at least > *related* to path resolution, flags like AT_REMOVEDIR and > AT_RECURSIVE aren't. > > * That point touches on something I see as a more fundamental problem > in the AT_ flags -- they were intended to be generic flags for all of > the ...at(2) syscalls. But then AT_ grew things like AT_STATX_ and > AT_REMOVEDIR (both of which are necessary features to have for their > respective syscalls, but now those flag bits are dead for other > syscalls -- not to mention the whole AT_SYMLINK_{NO,}FOLLOW thing). > > * While the above might be seen as minor quibbles, the really big > issue is that even the flags which are "similar" (AT_SYMLINK_NOFOLLOW > and RESOLVE_NO_SYMLINKS) have different semantics (by design -- in my > view, AT_SYMLINK_{NO,}FOLLOW / O_NOFOLLOW / lstat(2) has always had > the wrong semantics if the intention was to be a way to safely avoid > resolving symlinks). > > But maybe I'm just overthinking what a merge of AT_ and RESOLVE_ would > look like -- would it on. Eugh, dropped the rest of that sentence: ... would it only be the few AT_ flags which are strictly related to path resolution (such as AT_EMPTY_PATH)? If so wouldn't that just mean we end up with two flag arguments for new syscalls? -- Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH