/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All Rights Reserved   */


/*
 * Copyright (c) 1980 Regents of the University of California.
 * All rights reserved. The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

/*
 * groups
 */

#include <sys/types.h>
#include <sys/param.h>
#include <alloca.h>
#include <grp.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>

static void showgroups(char *user);

int
main(int argc, char *argv[])
{
        int ngroups, i;
        char *sep = "";
        struct group *gr;
        gid_t *groups;
        int maxgrp = sysconf(_SC_NGROUPS_MAX);

        groups = alloca(maxgrp * sizeof (gid_t));

        if (argc > 1) {
                for (i = 1; i < argc; i++)
                        showgroups(argv[i]);
                exit(0);
        }

        ngroups = getgroups(maxgrp, groups);
        if (getpwuid(getuid()) == NULL) {
                (void) fprintf(stderr, "groups: could not find passwd entry\n");
                exit(1);
        }

        for (i = 0; i < ngroups; i++) {
                gr = getgrgid(groups[i]);
                if (gr == NULL) {
                        (void) printf("%s%u", sep, groups[i]);
                        sep = " ";
                        continue;
                }
                (void) printf("%s%s", sep, gr->gr_name);
                sep = " ";
        }

        (void) printf("\n");
        return (0);
}

static void
showgroups(char *user)
{
        struct group *gr;
        struct passwd *pw;
        char **cp;
        char *sep = "";
        int pwgid_printed = 0;

        if ((pw = getpwnam(user)) == NULL) {
                (void) fprintf(stderr, "groups: %s : No such user\n", user);
                return;
        }
        setgrent();
        (void) printf("%s : ", user);
        while (gr = getgrent()) {
                if (pw->pw_gid == gr->gr_gid) {
                        /*
                         * To avoid duplicate group entries
                         */
                        if (pwgid_printed == 0) {
                                (void) printf("%s%s", sep, gr->gr_name);
                                sep = " ";
                                pwgid_printed = 1;
                        }
                        continue;
                }
                for (cp = gr->gr_mem; cp && *cp; cp++)
                        if (strcmp(*cp, user) == 0) {
                                (void) printf("%s%s", sep, gr->gr_name);
                                sep = " ";
                                break;
                        }
        }
        (void) printf("\n");
        endgrent();
}