SETRESUID(2)

NAME
setresuid, setresgid - set real, effective and saved user or group ID

SYNOPSIS
#define _GNU_SOURCE
#include <unistd.h>

int setresuid(uid_t ruid, uid_t euid, uid_t suid);
int setresgid(gid_t rgid, gid_t egid, gid_t sgid);

DESCRIPTION
setresuid sets the real user ID, the effective user ID, and the saved set-user-ID of the current process. Unprivileged user processes (i.e., processes with each of real, effective and saved user ID nonzero) may change the real, effective and saved user ID, each to one of: the current uid, the current effective uid or the current saved uid. The super-user may set real, effective and saved user ID to arbitrary values. If one of the parameters equals -1, the corresponding value is not changed. Completely analogously, setresgid sets the real, effective and saved group ID's of the current process, with the same restrictions for processes with each of real, effective and saved user ID nonzero.

RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.

ERRORS

EPERM
    The current process was not privileged and tried to change the IDs is a not allowed way.

EAGAIN
    uid does not match the current uid and this call would bring that userID over its NPROC rlimit.

CONFORMING TO
This call is nonstandard.

HISTORY
This system call was first introduced in HP-UX. It is available under Linux since Linux 2.1.44. These days it is also found in FreeBSD (for emulation of Linux binaries).

NOTES
Under HP-UX and FreeBSD the prototype is found in <unistd.h>. Under Linux the prototype is given by glibc since version 2.3.2 provided _GNU_SOURCE is defined.

SEE ALSO
getuid(2), setuid(2), setreuid(2), getresuid(2)