setreuid()
sets real and effective user IDs of the calling process.
Supplying a value of -1 for either the real or effective user ID forces
the system to leave that ID unchanged.
Unprivileged processes may only set the effective user ID to the real user ID,
the effective user ID or the saved set-user-ID.
POSIX: It is unspecified whether unprivileged processes may set the
real user ID to the real user ID, the effective user ID or the
saved set-user-ID.
Linux: Unprivileged users may only set the real user ID to
the real user ID or the effective user ID.
Linux: If the real user ID is set or the effective user ID is set to a value
not equal to the previous real user ID,
the saved set-user-ID will be set to the new effective user ID.
Completely analogously,
setregid()
sets real and effective group ID's of the calling process,
and all of the above holds with "group" instead of "user".
RETURN VALUE
On success, zero is returned.
On error, -1 is returned, and
errno
is set appropriately.
ERRORS
EPERM
The calling process is not privileged
(Linux: does not have the
CAP_SETUID
capability in the case of
setreuid(),
or the
CAP_SETGID
capability in the case of
setregid())
and a change other than (i)
swapping the effective user (group) ID with the real user (group) ID,
or (ii) setting one to the value of the other or (iii) setting the
effective user (group) ID to the value of the
saved set-user-ID (saved set-group-ID) was specified.
CONFORMING TO
POSIX.1-2001, 4.3BSD (the
setreuid()
and
setregid()
function calls first appeared in 4.2BSD).
NOTES
Setting the effective user (group) ID to the
saved set-user-ID (saved set-group-ID) is
possible since Linux 1.1.37 (1.1.38).
This page is part of release 3.14 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
