trusty (3) setreuid.3posix.gz

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NAME
       setreuid - set real and effective user IDs


SYNOPSIS
       #include <unistd.h>

       int setreuid(uid_t ruid, uid_t euid);


DESCRIPTION
       The  setreuid()  function  shall set the real and effective user IDs of the current process to the values
       specified by the ruid and euid arguments. If ruid or euid is -1, the corresponding effective or real user
       ID of the current process shall be left unchanged.

       A  process  with appropriate privileges can set either ID to any value.  An unprivileged process can only
       set the effective user ID if the euid argument is equal to either the real, effective, or saved  user  ID
       of the process.

       It  is  unspecified whether a process without appropriate privileges is permitted to change the real user
       ID to match the current real, effective, or saved set-user-ID of the process.


RETURN VALUE
       Upon successful completion, 0 shall be returned. Otherwise,  -1  shall  be  returned  and  errno  set  to
       indicate the error.


ERRORS
       The setreuid() function shall fail if:

       EINVAL The value of the ruid or euid argument is invalid or out-of-range.

       EPERM  The current process does not have appropriate privileges, and either an attempt was made to change
              the effective user ID to a value other than the real user  ID  or  the  saved  set-user-ID  or  an
              attempt was made to change the real user ID to a value not permitted by the implementation.

       The following sections are informative.


EXAMPLES
   Setting the Effective User ID to the Real User ID
       The  following  example  sets  the  effective user ID of the calling process to the real user ID, so that
       files created later will be owned by the current user.

              #include <unistd.h>
              #include <sys/types.h>
              ...
              setreuid(getuid(), getuid());
              ...


APPLICATION USAGE
       None.


RATIONALE
       None.


FUTURE DIRECTIONS
       None.


SEE ALSO
       getegid() , geteuid() , getgid() , getuid() , setegid() , seteuid() , setgid() , setregid() , setuid()  ,
       the Base Definitions volume of IEEE Std 1003.1-2001, <unistd.h>


       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition,
       Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open  Group  Base
       Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers,
       Inc and The Open Group. In the event of any discrepancy between this version and the  original  IEEE  and
       The  Open  Group  Standard,  the  original  IEEE and The Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .