/*-
 * Copyright (c) 1991, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1991, 1993\
 The Regents of the University of California.  All rights reserved.");
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)id.c        8.3 (Berkeley) 4/28/95";
#else
__RCSID("$NetBSD: id.c,v 1.32 2011/09/16 15:39:26 joerg Exp $");
#endif
#endif /* not lint */

#include <sys/param.h>

#include <err.h>
#include <errno.h>
#include <grp.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static void current(void);
static void pretty(struct passwd *);
static void group(struct passwd *, int);
__dead static void usage(void);
static void user(struct passwd *);
static struct passwd *who(char *);

static int maxgroups;
static gid_t *groups;

int
main(int argc, char *argv[])
{
        struct group *gr;
        struct passwd *pw;
        int ch, id;
        int Gflag, gflag, nflag, pflag, rflag, uflag;
        const char *opts;

        Gflag = gflag = nflag = pflag = rflag = uflag = 0;

        if (strcmp(getprogname(), "groups") == 0) {
                Gflag = 1;
                nflag = 1;
                opts = "";
                if (argc > 2)
                        usage();
        } else if (strcmp(getprogname(), "whoami") == 0) {
                uflag = 1;
                nflag = 1;
                opts = "";
                if (argc > 1)
                        usage();
        } else
                opts = "Ggnpru";

        while ((ch = getopt(argc, argv, opts)) != -1)
                switch (ch) {
                case 'G':
                        Gflag = 1;
                        break;
                case 'g':
                        gflag = 1;
                        break;
                case 'n':
                        nflag = 1;
                        break;
                case 'p':
                        pflag = 1;
                        break;
                case 'r':
                        rflag = 1;
                        break;
                case 'u':
                        uflag = 1;
                        break;
                case '?':
                default:
                        usage();
                }
        argc -= optind;
        argv += optind;

        switch (Gflag + gflag + pflag + uflag) {
        case 1:
                break;
        case 0:
                if (!nflag && !rflag)
                        break;
                /* FALLTHROUGH */
        default:
                usage();
        }

        if (strcmp(opts, "") != 0 && argc > 1)
                usage();

        pw = *argv ? who(*argv) : NULL;

        maxgroups = sysconf(_SC_NGROUPS_MAX);
        if ((groups = malloc((maxgroups + 1) * sizeof(gid_t))) == NULL)
                err(1, NULL);

        if (gflag) {
                id = pw ? pw->pw_gid : rflag ? getgid() : getegid();
                if (nflag && (gr = getgrgid(id)))
                        (void)printf("%s\n", gr->gr_name);
                else
                        (void)printf("%u\n", id);
                goto done;
        }

        if (uflag) {
                id = pw ? pw->pw_uid : rflag ? getuid() : geteuid();
                if (nflag && (pw = getpwuid(id)))
                        (void)printf("%s\n", pw->pw_name);
                else
                        (void)printf("%u\n", id);
                goto done;
        }

        if (Gflag) {
                group(pw, nflag);
                goto done;
        }

        if (pflag) {
                pretty(pw);
                goto done;
        }

        if (pw)
                user(pw);
        else
                current();
done:
        free(groups);

        return 0;
}

static void
pretty(struct passwd *pw)
{
        struct group *gr;
        u_int eid, rid;
        char *login;

        if (pw) {
                (void)printf("uid\t%s\n", pw->pw_name);
                (void)printf("groups\t");
                group(pw, 1);
        } else {
                if ((login = getlogin()) == NULL)
                        err(1, "getlogin");

                pw = getpwuid(rid = getuid());
                if (pw == NULL || strcmp(login, pw->pw_name))
                        (void)printf("login\t%s\n", login);
                if (pw)
                        (void)printf("uid\t%s\n", pw->pw_name);
                else
                        (void)printf("uid\t%u\n", rid);

                if ((eid = geteuid()) != rid) {
                        if ((pw = getpwuid(eid)) != NULL)
                                (void)printf("euid\t%s\n", pw->pw_name);
                        else
                                (void)printf("euid\t%u\n", eid);
                }
                if ((rid = getgid()) != (eid = getegid())) {
                        if ((gr = getgrgid(rid)) != NULL)
                                (void)printf("rgid\t%s\n", gr->gr_name);
                        else
                                (void)printf("rgid\t%u\n", rid);
                }
                (void)printf("groups\t");
                group(NULL, 1);
        }
}

static void
current(void)
{
        struct group *gr;
        struct passwd *pw;
        gid_t gid, egid, lastid;
        uid_t uid, euid;
        int cnt, ngroups;
        const char *fmt;

        uid = getuid();
        (void)printf("uid=%ju", (uintmax_t)uid);
        if ((pw = getpwuid(uid)) != NULL)
                (void)printf("(%s)", pw->pw_name);
        gid = getgid();
        (void)printf(" gid=%ju", (uintmax_t)gid);
        if ((gr = getgrgid(gid)) != NULL)
                (void)printf("(%s)", gr->gr_name);
        if ((euid = geteuid()) != uid) {
                (void)printf(" euid=%ju", (uintmax_t)euid);
                if ((pw = getpwuid(euid)) != NULL)
                        (void)printf("(%s)", pw->pw_name);
        }
        if ((egid = getegid()) != gid) {
                (void)printf(" egid=%ju", (uintmax_t)egid);
                if ((gr = getgrgid(egid)) != NULL)
                        (void)printf("(%s)", gr->gr_name);
        }
        if ((ngroups = getgroups(maxgroups, groups)) != 0) {
                for (fmt = " groups=%ju", lastid = -1, cnt = 0; cnt < ngroups;
                    fmt = ",%ju", lastid = gid, cnt++) {
                        gid = groups[cnt];
                        if (lastid == gid)
                                continue;
                        (void)printf(fmt, (uintmax_t)gid);
                        if ((gr = getgrgid(gid)) != NULL)
                                (void)printf("(%s)", gr->gr_name);
                }
        }
        (void)printf("\n");
}

static void
user(struct passwd *pw)
{
        struct group *gr;
        const char *fmt;
        int cnt, id, lastid, ngroups;
        gid_t *glist = groups;

        id = pw->pw_uid;
        (void)printf("uid=%u(%s)", id, pw->pw_name);
        (void)printf(" gid=%lu", (u_long)pw->pw_gid);
        if ((gr = getgrgid(pw->pw_gid)) != NULL)
                (void)printf("(%s)", gr->gr_name);
        ngroups = maxgroups + 1;
        if (getgrouplist(pw->pw_name, pw->pw_gid, glist, &ngroups) == -1) {
                glist = malloc(ngroups * sizeof(gid_t));
                (void) getgrouplist(pw->pw_name, pw->pw_gid, glist, &ngroups);
        }
        for (fmt = " groups=%u", lastid = -1, cnt = 0; cnt < ngroups;
            fmt=",%u", lastid = id, cnt++) {
                id = glist[cnt];
                if (lastid == id)
                        continue;
                (void)printf(fmt, id);
                if ((gr = getgrgid(id)) != NULL)
                        (void)printf("(%s)", gr->gr_name);
        }
        (void)printf("\n");
        if (glist != groups)
                free(glist);
}

static void
group(struct passwd *pw, int nflag)
{
        struct group *gr;
        int cnt, ngroups;
        gid_t id, lastid;
        const char *fmt;
        gid_t *glist = groups;

        if (pw) {
                ngroups = maxgroups;
                if (getgrouplist(pw->pw_name, pw->pw_gid, glist, &ngroups)
                    == -1) {
                        glist = malloc(ngroups * sizeof(gid_t));
                        (void) getgrouplist(pw->pw_name, pw->pw_gid, glist,
                                            &ngroups);
                }
        } else {
                glist[0] = getgid();
                ngroups = getgroups(maxgroups, glist + 1) + 1;
        }
        fmt = nflag ? "%s" : "%u";
        for (lastid = -1, cnt = 0; cnt < ngroups; ++cnt) {
                if (lastid == (id = glist[cnt]) || (cnt && id == glist[0]))
                        continue;
                if (nflag) {
                        if ((gr = getgrgid(id)) != NULL)
                                (void)printf(fmt, gr->gr_name);
                        else
                                (void)printf(*fmt == ' ' ? " %u" : "%u",
                                    id);
                        fmt = " %s";
                } else {
                        (void)printf(fmt, id);
                        fmt = " %u";
                }
                lastid = id;
        }
        (void)printf("\n");
        if (glist != groups)
                free(glist);
}

static struct passwd *
who(char *u)
{
        struct passwd *pw;
        long id;
        char *ep;

        /*
         * Translate user argument into a pw pointer.  First, try to
         * get it as specified.  If that fails, try it as a number.
         */
        if ((pw = getpwnam(u)) != NULL)
                return pw;
        id = strtol(u, &ep, 10);
        if (*u && !*ep && (pw = getpwuid(id)))
                return pw;
        errx(1, "%s: No such user", u);
        /* NOTREACHED */
        return NULL;
}

static void
usage(void)
{

        if (strcmp(getprogname(), "groups") == 0) {
                (void)fprintf(stderr, "usage: groups [user]\n");
        } else if (strcmp(getprogname(), "whoami") == 0) {
                (void)fprintf(stderr, "usage: whoami\n");
        } else {
                (void)fprintf(stderr, "usage: id [user]\n");
                (void)fprintf(stderr, "       id -G [-n] [user]\n");
                (void)fprintf(stderr, "       id -g [-nr] [user]\n");
                (void)fprintf(stderr, "       id -p [user]\n");
                (void)fprintf(stderr, "       id -u [-nr] [user]\n");
        }
        exit(1);
}