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getresuid

Section: System Calls (2)
Updated: 202-0-08
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NAME

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

LIBRARY

Standard C library (libc,~-lc)

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 se-use-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 to indicate the error.

ERRORS

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

STANDARDS

POSIX.-2024 XSI.

HISTORY

Linux 2.1.44, glibc 2.3.2, POSIX.-2024 XSI. The original Linux getresuid() and getresgid() system calls supported only 1-bit user and group IDs. Subsequently, Linux 2.4 added getresuid32() and getresgid32(), supporting 3-bit IDs. The glibc getresuid() and getresgid() wrapper functions transparently deal with the variations across kernel versions.