GETRESUID(2)

NAME
getresuid, getresgid - get real, effective and saved user/group IDs

SYNOPSIS
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <unistd.h>

int getresuid(uid_t *ruid, uid_t *euid, uid_t *suid);
int getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid);

DESCRIPTION
getresuid() returns the real UID, the effective UID, and the saved set-user-ID of the calling process, in the arguments ruid, euid, and suid, respectively. getresgid() performs the analogous task for the process's group IDs.

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

ERRORS

EFAULT
    One of the arguments specified an address outside the calling program's address space.

VERSIONS
These system calls appeared on Linux starting with kernel 2.1.44.

The prototypes are given by glibc since version 2.3.2, provided _GNU_SOURCE is defined.

CONFORMING TO
These calls are nonstandard; they also appear on HP-UX and some of the BSDs.

NOTES
The original Linux getresuid() and getresgid() system calls supported only 16-bit user and group IDs. Subsequently, Linux 2.4 added getresuid32() and getresgid32(), supporting 32-bit IDs. The glibc getresuid() and getresgid() wrapper functions transparently deal with the variations across kernel versions.

SEE ALSO
getuid(2), setresuid(2), setreuid(2), setuid(2), credentials(7)

COLOPHON
This page is part of release 4.16 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.