NAME    [Toc]    [Back]

     setreuid - set real and effective user IDs

SYNOPSIS    [Toc]    [Back]

     #include <unistd.h>

     int
     setreuid(uid_t ruid, uid_t euid);

DESCRIPTION    [Toc]    [Back]

     The real and effective user IDs of the current  process  are
set according
     to  the  arguments.   If the real user ID is changed, or the
effective user
     ID is changed to a value other than the real user  ID,  then
the saved user
     ID will be set to the effective user ID.

     Unprivileged  users may change either user ID to the current
value of the
     real, effective, or saved user ID.  Only the  superuser  may
make other
     changes.

     Supplying a value of -1 for either the real or effective user ID forces
     the system to substitute the current ID in place of  the  -1
parameter.

     The  setreuid()  function was intended to allow swapping the
real and effective
 user IDs in set-user-ID programs to temporarily  relinquish the
     set-user-ID value.  This purpose is now better served by the
use of the
     seteuid() function (see setuid(2)).

     When setting the real and effective user  IDs  to  the  same
value, the
     setuid() function is preferred.

RETURN VALUES    [Toc]    [Back]

     Upon  successful completion, a value of 0 is returned.  Otherwise, a value
     of -1 is returned and errno is set to indicate the error.

ERRORS    [Toc]    [Back]

     [EPERM]       The current process is not the superuser and a
change other
                   than changing the effective user ID to the real user ID was
                   specified.

SEE ALSO    [Toc]    [Back]

     getuid(2), seteuid(2), setresuid(2), setuid(2)

STANDARDS    [Toc]    [Back]

     The setreuid() function conforms to the IEEE Std 1003.1-2001
(``POSIX'')
     and X/Open Portability Guide Issue 4.3 (``XPG4.3'').  specifications.

     Note,  however,  that  prior   to   IEEE   Std   1003.1-2001
(``POSIX''), the
     setreuid()  function  was  not a part of the IEEE Std 1003.1
(``POSIX'')
     specification.  As a result, it may not  be  implemented  on
all systems.

HISTORY    [Toc]    [Back]

     The setreuid() function call appeared in 4.2BSD.  A semantically different
 version appeared in 4.4BSD.  The current  version,  with
the original
     semantics restored, appeared in OpenBSD 3.3.

CAVEATS    [Toc]    [Back]

     The setreuid() function predates POSIX saved user IDs.  This
implementation
 changes the saved user ID to the new value of  the  effective user ID
     if  the  real user ID is changed.  Other implementations may
behave differently.


OpenBSD     3.6                        January      29,      2003