source: MondoRescue/branches/2.2.9/mindi-busybox/coreutils/id.c@ 3320

/* vi: set sw=4 ts=4: */
/*
 * Mini id implementation for busybox
 *
 * Copyright (C) 2000 by Randolph Chung <tausq@debian.org>
 * Copyright (C) 2008 by Tito Ragusa <farmatito@tiscali.it>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

/* BB_AUDIT SUSv3 compliant. */
/* Hacked by Tito Ragusa (C) 2004 to handle usernames of whatever
 * length and to be more similar to GNU id.
 * -Z option support: by Yuichi Nakamura <ynakam@hitachisoft.jp>
 * Added -G option Tito Ragusa (C) 2008 for SUSv3.
 */

#include "libbb.h"

/* This is a NOEXEC applet. Be very careful! */

#if !ENABLE_USE_BB_PWD_GRP
#if defined(__UCLIBC_MAJOR__) && (__UCLIBC_MAJOR__ == 0)
#if (__UCLIBC_MINOR__ < 9) || (__UCLIBC_MINOR__ == 9 &&  __UCLIBC_SUBLEVEL__ < 30)
#error "Sorry, you need at least uClibc version 0.9.30 for id applet to build"
#endif
#endif
#endif

enum {
    PRINT_REAL      = (1 << 0),
    NAME_NOT_NUMBER = (1 << 1),
    JUST_USER       = (1 << 2),
    JUST_GROUP      = (1 << 3),
    JUST_ALL_GROUPS = (1 << 4),
#if ENABLE_SELINUX
    JUST_CONTEXT    = (1 << 5),
#endif
};

static int print_common(unsigned id, const char *name, const char *prefix)
{
    if (prefix) {
        printf("%s", prefix);
    }
    if (!(option_mask32 & NAME_NOT_NUMBER) || !name) {
        printf("%u", id);
    }
    if (!option_mask32 || (option_mask32 & NAME_NOT_NUMBER)) {
        if (name) {
            printf(option_mask32 ? "%s" : "(%s)", name);
        } else {
            /* Don't set error status flag in default mode */
            if (option_mask32) {
                if (ENABLE_DESKTOP)
                    bb_error_msg("unknown ID %u", id);
                return EXIT_FAILURE;
            }
        }
    }
    return EXIT_SUCCESS;
}

static int print_group(gid_t id, const char *prefix)
{
    return print_common(id, gid2group(id), prefix);
}

static int print_user(uid_t id, const char *prefix)
{
    return print_common(id, uid2uname(id), prefix);
}

/* On error set *n < 0 and return >= 0
 * If *n is too small, update it and return < 0
 *  (ok to trash groups[] in both cases)
 * Otherwise fill in groups[] and return >= 0
 */
static int get_groups(const char *username, gid_t rgid, gid_t *groups, int *n)
{
    int m;

    if (username) {
        /* If the user is a member of more than
         * *n groups, then -1 is returned. Otherwise >= 0.
         * (and no defined way of detecting errors?!) */
        m = getgrouplist(username, rgid, groups, n);
        /* I guess *n < 0 might indicate error. Anyway,
         * malloc'ing -1 bytes won't be good, so: */
        //if (*n < 0)
        //  return 0;
        //return m;
        //commented out here, happens below anyway
    } else {
        /* On error -1 is returned, which ends up in *n */
        int nn = getgroups(*n, groups);
        /* 0: nn <= *n, groups[] was big enough; -1 otherwise */
        m = - (nn > *n);
        *n = nn;
    }
    if (*n < 0)
        return 0; /* error, don't return < 0! */
    return m;
}

int id_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int id_main(int argc UNUSED_PARAM, char **argv)
{
    uid_t ruid;
    gid_t rgid;
    uid_t euid;
    gid_t egid;
    unsigned opt;
    int i;
    int status = EXIT_SUCCESS;
    const char *prefix;
    const char *username;
#if ENABLE_SELINUX
    security_context_t scontext = NULL;
#endif
    /* Don't allow -n -r -nr -ug -rug -nug -rnug -uZ -gZ -GZ*/
    /* Don't allow more than one username */
    opt_complementary = "?1:u--g:g--u:G--u:u--G:g--G:G--g:r?ugG:n?ugG"
             IF_SELINUX(":u--Z:Z--u:g--Z:Z--g:G--Z:Z--G");
    opt = getopt32(argv, "rnugG" IF_SELINUX("Z"));

    username = argv[optind];
    if (username) {
        struct passwd *p = xgetpwnam(username);
        euid = ruid = p->pw_uid;
        egid = rgid = p->pw_gid;
    } else {
        egid = getegid();
        rgid = getgid();
        euid = geteuid();
        ruid = getuid();
    }
    /* JUST_ALL_GROUPS ignores -r PRINT_REAL flag even if man page for */
    /* id says: print the real ID instead of the effective ID, with -ugG */
    /* in fact in this case egid is always printed if egid != rgid */
    if (!opt || (opt & JUST_ALL_GROUPS)) {
        gid_t *groups;
        int n;

        if (!opt) {
            /* Default Mode */
            status |= print_user(ruid, "uid=");
            status |= print_group(rgid, " gid=");
            if (euid != ruid)
                status |= print_user(euid, " euid=");
            if (egid != rgid)
                status |= print_group(egid, " egid=");
        } else {
            /* JUST_ALL_GROUPS */
            status |= print_group(rgid, NULL);
            if (egid != rgid)
                status |= print_group(egid, " ");
        }
        /* We are supplying largish buffer, trying
         * to not run get_groups() twice. That might be slow
         * ("user database in remote SQL server" case) */
        groups = xmalloc(64 * sizeof(gid_t));
        n = 64;
        if (get_groups(username, rgid, groups, &n) < 0) {
            /* Need bigger buffer after all */
            groups = xrealloc(groups, n * sizeof(gid_t));
            get_groups(username, rgid, groups, &n);
        }
        if (n > 0) {
            /* Print the list */
            prefix = " groups=";
            for (i = 0; i < n; i++) {
                if (opt && (groups[i] == rgid || groups[i] == egid))
                    continue;
                status |= print_group(groups[i], opt ? " " : prefix);
                prefix = ",";
            }
        } else if (n < 0) { /* error in get_groups() */
            if (!ENABLE_DESKTOP)
                bb_error_msg_and_die("can't get groups");
            else
                return EXIT_FAILURE;
        }
        if (ENABLE_FEATURE_CLEAN_UP)
            free(groups);
#if ENABLE_SELINUX
        if (is_selinux_enabled()) {
            if (getcon(&scontext) == 0)
                printf(" context=%s", scontext);
        }
#endif
    } else if (opt & PRINT_REAL) {
        euid = ruid;
        egid = rgid;
    }

    if (opt & JUST_USER)
        status |= print_user(euid, NULL);
    else if (opt & JUST_GROUP)
        status |= print_group(egid, NULL);
#if ENABLE_SELINUX
    else if (opt & JUST_CONTEXT) {
        selinux_or_die();
        if (username || getcon(&scontext)) {
            bb_error_msg_and_die("can't get process context%s",
                username ? " for a different user" : "");
        }
        fputs(scontext, stdout);
    }
    /* freecon(NULL) seems to be harmless */
    if (ENABLE_FEATURE_CLEAN_UP)
        freecon(scontext);
#endif
    bb_putchar('\n');
    fflush_stdout_and_exit(status);
}