/*
 * This file and its contents are supplied under the terms of the
 * Common Development and Distribution License ("CDDL"), version 1.0.
 * You may only use this file in accordance with the terms of version
 * 1.0 of the CDDL.
 *
 * A full copy of the text of the CDDL should have accompanied this
 * source.  A copy of the CDDL is also available via the Internet at
 * http://www.illumos.org/license/CDDL.
 */

/*
 * Copyright 2019 Robert Mustacchi
 */

#include <unistd.h>
#include <err.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <pwd.h>
#include <libgen.h>
#include <locale.h>
#include <libintl.h>

int
main(int argc, char *argv[])
{
        char *name;
        char uidbuf[32];

        (void) setlocale(LC_ALL, "");
#if !defined(TEXT_DOMAIN)
#define TEXT_DOMAIN "SYS_TEST"
#endif
        (void) textdomain(TEXT_DOMAIN);

        if (argc != 1) {
                warnx(gettext("illegal arguments"));
                (void) fprintf(stderr, gettext("Usage: %s\n"),
                    basename(argv[0]));
                return (1);
        }

        /*
         * In some cases getlogin() can fail. The most common case is due to
         * something like using script(1). Deal with that by falling back to the
         * current user ID, which is as accurate as we can be. This is what the
         * ksh93 version used to do.
         */
        name = getlogin();
        if (name == NULL) {
                uid_t uid;
                struct passwd *pass;

                uid = getuid();
                pass = getpwuid(uid);
                if (pass != NULL) {
                        name = pass->pw_name;
                } else {
                        (void) snprintf(uidbuf, sizeof (uidbuf), "%u", uid);
                        name = uidbuf;
                }
        }

        if (printf("%s\n", name) == -1) {
                err(EXIT_FAILURE, gettext("failed to write out login name"));
        }

        return (0);
}