setreuid

Purpose

     Sets real and effective user ID.

Library

     Berkeley Library (libbsd.a)

Syntax

     int setreuid (ruid, uid)
     int ruid, euid;

Description

     The setreuid subroutine sets  the real and effective user
     ID  of the  current process  according to  the parameters
     ruid and euid.  If either  of these parameters equals -1,
     the current user ID is used.

     Any process can change the  real user ID or the effective
     user ID to  the other, but only a process  with an effec-
     tive  user  ID  of  superuser can  make  other  kinds  of
     changes.

     If you need the setruid or seteuid functions, they can be
     constructed as:

       #define seteuid(id) setreuid(-1, (id))
       #define setruid(id) setreuid((id), -1)

Return Value

     When the call succeeds, a value of 0 is returned.  If the
     setreuid subroutine fails, a value  of -1 is returned and
     errno is set to indicate the error.

Diagnostics

     EPERM      The current process does not have an effective
                user ID of  superuser.  This process attempted
                a change other than from the effective user ID
                to the real user ID.

Related Information

     In  this book:   "getuid, geteuid,  getgid, getegid"  and
     "setuid, setgid."