setreuid(2) [ultrix man page]
setreuid(2) System Calls Manual setreuid(2) Name setreuid - set real and effective user ID's Syntax setreuid(ruid, euid) intruid, euid; Description The real and effective user ID's of the current process are set according to the arguments. If ruid or euid is -1, the current uid is filled in by the system. Return Values Upon successful completion, a value of zero (0) is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error. Environment BSD If the process is superuser, or and matches with the real user ID, the effective user ID, or the saved set-user-id (as described in ), then the real, effective, and the saved set-user-id are set to and respectively. POSIX SYSTEM-FIVE When your program is compiled in the POSIX or SYSTEM-FIVE mode, if both arguments to are -1, the system call returns a value of -1 and errno is set to [EINVAL]. The following semantics apply when using the function: If the process is the superuser, the real, effective, and saved set-user-id (as described in ) are set to and respectively. If the process is not the superuser, but the and matches with the real user ID, the effective user ID (only in the SYSTEM-FIVE and BSD environments), or the saved set-user-id, then the effective ID is set to The real user ID and the saved set-user-id are left unchanged. Diagnostics [EPERM] The current process is not the superuser and the and specified does not match with the real user ID, the effective user ID (only in SYSTEM-FIVE and BSD environment), or the saved set-user-id. See Also getuid(2), setregid(2), setuid(3) setreuid(2)
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setreuid(2) System Calls setreuid(2) NAME
setreuid - set real and effective user IDs SYNOPSIS
#include <unistd.h> int setreuid(uid_t ruid, uid_t euid); DESCRIPTION
The setreuid() function is used to set the real and effective user IDs of the calling process. If ruid is -1, the real user ID is not changed; if euid is -1, the effective user ID is not changed. The real and effective user IDs may be set to different values in the same call. If the {PRIV_PROC_SETID} privilege is asserted in the effective set of the calling process, the real user ID and the effective user ID can be set to any legal value. If the {PRIV_PROC_SETID} privilege is not asserted in the effective set of the calling process, either the real user ID can be set to the effective user ID, or the effective user ID can either be set to the saved set-user ID from execve() (seeexec(2)) or the real user ID. In either case, if the real user ID is being changed (that is, if ruid is not -1), or the effective user ID is being changed to a value not equal to the real user ID, the saved set-user ID is set equal to the new effective user ID. All privileges are required to change to uid 0. RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, -1 is returned, errno is set to indicate the error, and neither of the user IDs will be changed. ERRORS
The setreuid() function will fail if: EINVAL The value of ruid or euid is less than 0 or greater than UID_MAX (defined in <limits.h>). EPERM The {PRIV_PROC_SETID} privilege is not asserted in the effective set of the calling processes and a change was specified other than changing the real user ID to the effective user ID, or changing the effective user ID to the real user ID or the saved set- user ID. See privileges(5) for additional restrictions which apply when changing to UID 0. USAGE
If a set-user-ID process sets its effective user ID to its real user ID, it can still set its effective user ID back to the saved set-user ID. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ SEE ALSO
exec(2), getuid(2), setregid(2), setuid(2), attributes(5), privileges(5), standards(5) SunOS 5.11 22 Mar 2004 setreuid(2)