euidaccessat [Re: one more openat-style function required: fchmodat

[Jim Meyering]

Roland McGrath <roland@redhat.com> wrote:
> Is Solaris eaccess the same as euidaccess?

Yes.  Irix and FreeBSD have eaccess, too.

> Should glibc provide eaccess as
> an alias for euidaccess?

Good idea.

> Except on the Hurd, euidaccess actually either just uses access (when r==e)
> or uses stat and the usual st_mode rules assuming those are what the
> filesystem will actually use, which you can do yourself.  rm et al I expect
> are never setuid and so can always use the method of calling access, which

I admit it is very unlikely that anyone will ever find
a use for an rm binary with the set-UID bit set.
However, rm might easily be invoked from a set-UID
program or script, and using access(2) in that context
would be wrong.

> is superior in telling truth about permission, but lacks the *at features.
>
> In keeping with the other interfaces, it should be faccessat and use a new
> AT_* flag bit to distinguish real-user from effective-user access checking.
>
> 	int faccessat (int fd, const char *file, int type, int flag);
>
> Does that sound reasonable?

That sounds fine.
Thanks!