/* vi: set sw=4 ts=4: */
/*
 * addgroup - add groups to /etc/group and /etc/gshadow
 *
 * Copyright (C) 1999 by Lineo, inc. and John Beppu
 * Copyright (C) 1999,2000,2001 by John Beppu <beppu@codepoet.org>
 * Copyright (C) 2007 by Tito Ragusa <farmatito@tiscali.it>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
//config:config ADDGROUP
//config:       bool "addgroup (8.6 kb)"
//config:       default y
//config:       select LONG_OPTS
//config:       help
//config:       Utility for creating a new group account.
//config:
//config:config FEATURE_ADDUSER_TO_GROUP
//config:       bool "Support adding users to groups"
//config:       default y
//config:       depends on ADDGROUP
//config:       help
//config:       If called with two non-option arguments,
//config:       addgroup will add an existing user to an
//config:       existing group.

//applet:IF_ADDGROUP(APPLET_NOEXEC(addgroup, addgroup, BB_DIR_USR_SBIN, BB_SUID_DROP, addgroup))

//kbuild:lib-$(CONFIG_ADDGROUP) += addgroup.o

//usage:#define addgroup_trivial_usage
//usage:       "[-g GID] [-S] " IF_FEATURE_ADDUSER_TO_GROUP("[USER] ") "GROUP"
//usage:#define addgroup_full_usage "\n\n"
//usage:       "Add a group" IF_FEATURE_ADDUSER_TO_GROUP(" or add a user to a group") "\n"
//usage:     "\n        -g GID  Group id"
//usage:     "\n        -S      Create a system group"

#include "libbb.h"

#if CONFIG_LAST_SYSTEM_ID < CONFIG_FIRST_SYSTEM_ID
#error Bad LAST_SYSTEM_ID or FIRST_SYSTEM_ID in .config
#endif
#if CONFIG_LAST_ID < CONFIG_LAST_SYSTEM_ID
#error Bad LAST_ID or LAST_SYSTEM_ID in .config
#endif

#define OPT_GID                       (1 << 0)
#define OPT_SYSTEM_ACCOUNT            (1 << 1)

static void xgroup_study(struct group *g)
{
        unsigned max = CONFIG_LAST_ID;

        /* Make sure gr_name is unused */
        if (getgrnam(g->gr_name)) {
                bb_error_msg_and_die("%s '%s' in use", "group", g->gr_name);
                /* these format strings are reused in adduser and addgroup */
        }

        /* if a specific gid is requested, the --system switch and */
        /* min and max values are overridden, and the range of valid */
        /* gid values is set to [0, INT_MAX] */
        if (!(option_mask32 & OPT_GID)) {
                if (option_mask32 & OPT_SYSTEM_ACCOUNT) {
                        g->gr_gid = CONFIG_FIRST_SYSTEM_ID;
                        max = CONFIG_LAST_SYSTEM_ID;
                } else {
                        g->gr_gid = CONFIG_LAST_SYSTEM_ID + 1;
                }
        }
        /* Check if the desired gid is free
         * or find the first free one */
        while (1) {
                if (!getgrgid(g->gr_gid)) {
                        return; /* found free group: return */
                }
                if (option_mask32 & OPT_GID) {
                        /* -g N, cannot pick gid other than N: error */
                        bb_error_msg_and_die("%s '%s' in use", "gid", itoa(g->gr_gid));
                        /* this format strings is reused in adduser and addgroup */
                }
                if (g->gr_gid == max) {
                        /* overflowed: error */
                        bb_error_msg_and_die("no %cids left", 'g');
                        /* this format string is reused in adduser and addgroup */
                }
                g->gr_gid++;
        }
}

/* append a new user to the passwd file */
static void new_group(char *group, gid_t gid)
{
        struct group gr;
        char *p;

        /* make sure gid and group haven't already been allocated */
        gr.gr_gid = gid;
        gr.gr_name = group;
        xgroup_study(&gr);

        /* add entry to group */
        p = xasprintf("x:%u:", (unsigned) gr.gr_gid);
        if (update_passwd(bb_path_group_file, group, p, NULL) < 0)
                exit(EXIT_FAILURE);
        if (ENABLE_FEATURE_CLEAN_UP)
                free(p);
#if ENABLE_FEATURE_SHADOWPASSWDS
        /* /etc/gshadow fields:
         * 1. Group name.
         * 2. Encrypted password.
         *    If set, non-members of the group can join the group
         *    by typing the password for that group using the newgrp command.
         *    If the value is of this field ! then no user is allowed
         *    to access the group using the newgrp command. A value of !!
         *    is treated the same as a value of ! only it indicates
         *    that a password has never been set before. If the value is null,
         *    only group members can log into the group.
         * 3. Group administrators (comma delimited list).
         *    Group members listed here can add or remove group members
         *    using the gpasswd command.
         * 4. Group members (comma delimited list).
         */
        /* Ignore errors: if file is missing we assume admin doesn't want it */
        update_passwd(bb_path_gshadow_file, group, "!::", NULL);
#endif
}

//FIXME: upstream addgroup has no short options! NOT COMPATIBLE!
static const char addgroup_longopts[] ALIGN1 =
                "gid\0"                 Required_argument "g"
                "system\0"              No_argument       "S"
                ;

/*
 * addgroup will take a login_name as its first parameter.
 *
 * gid can be customized via command-line parameters.
 * If called with two non-option arguments, addgroup
 * will add an existing user to an existing group.
 */
int addgroup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int addgroup_main(int argc UNUSED_PARAM, char **argv)
{
#if ENABLE_FEATURE_ADDUSER_TO_GROUP
        unsigned opts;
#endif
        const char *gid = "0";

        /* need to be root */
        if (geteuid()) {
                bb_error_msg_and_die(bb_msg_perm_denied_are_you_root);
        }
        /* Syntax:
         *  addgroup group
         *  addgroup --gid num group
         *  addgroup user group
         * Check for min, max and missing args */
#if ENABLE_FEATURE_ADDUSER_TO_GROUP
        opts =
#endif
        getopt32long(argv, "^" "g:S" "\0" "-1:?2", addgroup_longopts,
                                &gid
        );
        /* move past the commandline options */
        argv += optind;
        //argc -= optind;

#if ENABLE_FEATURE_ADDUSER_TO_GROUP
        if (argv[1]) {
                struct group *gr;

                if (opts & OPT_GID) {
                        /* -g was there, but "addgroup -g num user group"
                         * is a no-no */
                        bb_show_usage();
                }

                /* check if group and user exist */
                xuname2uid(argv[0]); /* unknown user: exit */
                gr = xgetgrnam(argv[1]); /* unknown group: exit */
                /* check if user is already in this group */
                for (; *(gr->gr_mem) != NULL; (gr->gr_mem)++) {
                        if (strcmp(argv[0], *(gr->gr_mem)) == 0) {
                                /* user is already in group: do nothing */
                                return EXIT_SUCCESS;
                        }
                }
                if (update_passwd(bb_path_group_file, argv[1], NULL, argv[0]) < 0) {
                        return EXIT_FAILURE;
                }
# if ENABLE_FEATURE_SHADOWPASSWDS
                update_passwd(bb_path_gshadow_file, argv[1], NULL, argv[0]);
# endif
        } else
#endif /* ENABLE_FEATURE_ADDUSER_TO_GROUP */
        {
                die_if_bad_username(argv[0]);
                new_group(argv[0], xatou_range(gid, 0, CONFIG_LAST_ID));
        }
        /* Reached only on success */
        return EXIT_SUCCESS;
}