[braindamaged?] use of access(2) -- long note

[Brandon Allbery]

As quoted from <368 at wsccs.UUCP> by terry at wsccs.UUCP (terry):
+---------------
| Steven, the access() function is supposed to check using the real user and
| group ID's.  This makes it do what it is documented as doing, ie: finding
| out if you have access, NOT if who you are effectively has access.
| 
| The process by which an exec() works is exactly that by which my example works;
| your euid and egid become your uid and gid.
| 
| > The difficulty is because the shell probably uses access(2) to see if
| > /usr/acct/bin/report is executable
| 
| It does.  Isn't that what it's supposed to do?
+---------------

Whoa!  exec() preserves uid/gid/euid/egid -- it does NOT set the uid to the
euid, or we'd have some massive secuity holes about (consider /bin/mkdir on
pre-4.2/SVR3 systems).

sh uses access()?  Since the real and effective u/gids are not affected by
an exec(), access() is the *wrong* function to use.
-- 
	      Brandon S. Allbery, moderator of comp.sources.misc
       {well!hoptoad,uunet!hnsurg3,cbosgd,sun!mandrill}!ncoast!allbery