objects with SF_IMMUTABLE, SF_APPEND, or SF_NOUNLINK.
* Document that non-superusers cannot set or clear any SF_* flag
(setting fails with EPERM, clearing is silently ignored).
* Document that superusers cannot change any flag if one of
SF_IMMUTABLE, SF_APPEND, SF_NOUNLINK is set and securelevel is
greater than 0.
* Document SF_SNAPSHOT and note that it is maintained by the
system and is, for this reason, impossible to set to clear by
any user.
PR: docs/33877
Submitted by: harti
Help by: George Marsellis <gam9478@njit.edu>
MFC after: 1 week
Stop calling system calls "function calls".
Use "The .Fn system call" a-la "The .Nm utility".
When referring to a non-BSD implementation in
the HISTORY section, call syscall a function,
to be safe.
These changes add the ability to specify that a UFS file/directory
cannot be unlinked. This is basically a scaled back version
of the IMMUTABLE flag. The reason is to allow an administrator
to create a directory hierarchy that a group of users
can arbitrarily add/delete files from, but that the hierarchy
itself is safe from removal by them.
If the NOUNLINK definition is set to 0
then this results in no change to what happens normally.
(and results in identical binary (in the kernel)).
It can be proven that if this bit is never set by the admin,
no new behaviour is introduced..
Several "good idea" comments from reviewers plus one grumble
about creeping featurism.
This code is in production in 2.2 based systems
in a bunch of man pages.
Use the correct .Bx (BSD UNIX) or .At (AT&T UNIX) macros
instead of explicitly specifying the version in the text
in a bunch of man pages.
