busybox: update to 1.23.2

[tomato.git] / release / src / router / busybox / modutils / modprobe.c

/* vi: set sw=4 ts=4: */
/*
 * Modprobe written from scratch for BusyBox
 *
 * Copyright (c) 2008 Timo Teras <timo.teras@iki.fi>
 * Copyright (c) 2008 Vladimir Dronnikov
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

//applet:IF_MODPROBE(APPLET(modprobe, BB_DIR_SBIN, BB_SUID_DROP))

#include "libbb.h"
#include "modutils.h"
#include <sys/utsname.h>
#include <fnmatch.h>

//#define DBG(fmt, ...) bb_error_msg("%s: " fmt, __func__, ## __VA_ARGS__)
#define DBG(...) ((void)0)

/* Note that unlike older versions of modules.dep/depmod (busybox and m-i-t),
 * we expect the full dependency list to be specified in modules.dep.
 * Older versions would only export the direct dependency list.
 */


//usage:#if !ENABLE_MODPROBE_SMALL
//usage:#define modprobe_notes_usage
//usage:        "modprobe can (un)load a stack of modules, passing each module options (when\n"
//usage:        "loading). modprobe uses a configuration file to determine what option(s) to\n"
//usage:        "pass each module it loads.\n"
//usage:        "\n"
//usage:        "The configuration file is searched (in this order):\n"
//usage:        "\n"
//usage:        "    /etc/modprobe.conf (2.6 only)\n"
//usage:        "    /etc/modules.conf\n"
//usage:        "    /etc/conf.modules (deprecated)\n"
//usage:        "\n"
//usage:        "They all have the same syntax (see below). If none is present, it is\n"
//usage:        "_not_ an error; each loaded module is then expected to load without\n"
//usage:        "options. Once a file is found, the others are tested for.\n"
//usage:        "\n"
//usage:        "/etc/modules.conf entry format:\n"
//usage:        "\n"
//usage:        "  alias <alias_name> <mod_name>\n"
//usage:        "    Makes it possible to modprobe alias_name, when there is no such module.\n"
//usage:        "    It makes sense if your mod_name is long, or you want a more representative\n"
//usage:        "    name for that module (eg. 'scsi' in place of 'aha7xxx').\n"
//usage:        "    This makes it also possible to use a different set of options (below) for\n"
//usage:        "    the module and the alias.\n"
//usage:        "    A module can be aliased more than once.\n"
//usage:        "\n"
//usage:        "  options <mod_name|alias_name> <symbol=value...>\n"
//usage:        "    When loading module mod_name (or the module aliased by alias_name), pass\n"
//usage:        "    the \"symbol=value\" pairs as option to that module.\n"
//usage:        "\n"
//usage:        "Sample /etc/modules.conf file:\n"
//usage:        "\n"
//usage:        "  options tulip irq=3\n"
//usage:        "  alias tulip tulip2\n"
//usage:        "  options tulip2 irq=4 io=0x308\n"
//usage:        "\n"
//usage:        "Other functionality offered by 'classic' modprobe is not available in\n"
//usage:        "this implementation.\n"
//usage:        "\n"
//usage:        "If module options are present both in the config file, and on the command line,\n"
//usage:        "then the options from the command line will be passed to the module _after_\n"
//usage:        "the options from the config file. That way, you can have defaults in the config\n"
//usage:        "file, and override them for a specific usage from the command line.\n"
//usage:#define modprobe_example_usage
//usage:       "(with the above /etc/modules.conf):\n\n"
//usage:       "$ modprobe tulip\n"
//usage:       "   will load the module 'tulip' with default option 'irq=3'\n\n"
//usage:       "$ modprobe tulip irq=5\n"
//usage:       "   will load the module 'tulip' with option 'irq=5', thus overriding the default\n\n"
//usage:       "$ modprobe tulip2\n"
//usage:       "   will load the module 'tulip' with default options 'irq=4 io=0x308',\n"
//usage:       "   which are the default for alias 'tulip2'\n\n"
//usage:       "$ modprobe tulip2 irq=8\n"
//usage:       "   will load the module 'tulip' with default options 'irq=4 io=0x308 irq=8',\n"
//usage:       "   which are the default for alias 'tulip2' overridden by the option 'irq=8'\n\n"
//usage:       "   from the command line\n\n"
//usage:       "$ modprobe tulip2 irq=2 io=0x210\n"
//usage:       "   will load the module 'tulip' with default options 'irq=4 io=0x308 irq=4 io=0x210',\n"
//usage:       "   which are the default for alias 'tulip2' overridden by the options 'irq=2 io=0x210'\n\n"
//usage:       "   from the command line\n"
//usage:
//usage:#define modprobe_trivial_usage
//usage:        "[-alrqvsD" IF_FEATURE_MODPROBE_BLACKLIST("b") "]"
//usage:        " MODULE [SYMBOL=VALUE]..."
//usage:#define modprobe_full_usage "\n\n"
//usage:       "        -a      Load multiple MODULEs"
//usage:     "\n        -l      List (MODULE is a pattern)"
//usage:     "\n        -r      Remove MODULE (stacks) or do autoclean"
//usage:     "\n        -q      Quiet"
//usage:     "\n        -v      Verbose"
//usage:     "\n        -s      Log to syslog"
//usage:     "\n        -D      Show dependencies"
//usage:        IF_FEATURE_MODPROBE_BLACKLIST(
//usage:     "\n        -b      Apply blacklist to module names too"
//usage:        )
//usage:#endif /* !ENABLE_MODPROBE_SMALL */

/* Note: usage text doesn't document various 2.4 options
 * we pull in through INSMOD_OPTS define
 * Note2: -b is always accepted, but if !FEATURE_MODPROBE_BLACKLIST,
 * it is a no-op.
 */
#define MODPROBE_OPTS  "alrDb"
/* -a and -D _are_ in fact compatible */
#define MODPROBE_COMPLEMENTARY ("q-v:v-q:l--arD:r--alD:a--lr:D--rl")
//#define MODPROBE_OPTS  "acd:lnrt:C:b"
//#define MODPROBE_COMPLEMENTARY "q-v:v-q:l--acr:a--lr:r--al"
enum {
        OPT_INSERT_ALL   = (INSMOD_OPT_UNUSED << 0), /* a */
        //OPT_DUMP_ONLY  = (INSMOD_OPT_UNUSED << x), /* c */
        //OPT_DIRNAME    = (INSMOD_OPT_UNUSED << x), /* d */
        OPT_LIST_ONLY    = (INSMOD_OPT_UNUSED << 1), /* l */
        //OPT_SHOW_ONLY  = (INSMOD_OPT_UNUSED << x), /* n */
        OPT_REMOVE       = (INSMOD_OPT_UNUSED << 2), /* r */
        //OPT_RESTRICT   = (INSMOD_OPT_UNUSED << x), /* t */
        //OPT_VERONLY    = (INSMOD_OPT_UNUSED << x), /* V */
        //OPT_CONFIGFILE = (INSMOD_OPT_UNUSED << x), /* C */
        OPT_SHOW_DEPS    = (INSMOD_OPT_UNUSED << 3), /* D */
        OPT_BLACKLIST    = (INSMOD_OPT_UNUSED << 4) * ENABLE_FEATURE_MODPROBE_BLACKLIST,
};
#if ENABLE_LONG_OPTS
static const char modprobe_longopts[] ALIGN1 =
        /* nobody asked for long opts (yet) */
        // "all\0"          No_argument "a"
        // "list\0"         No_argument "l"
        // "remove\0"       No_argument "r"
        // "quiet\0"        No_argument "q"
        // "verbose\0"      No_argument "v"
        // "syslog\0"       No_argument "s"
        /* module-init-tools 3.11.1 has only long opt --show-depends
         * but no short -D, we provide long opt for scripts which
         * were written for 3.11.1: */
        "show-depends\0"     No_argument "D"
        // "use-blacklist\0" No_argument "b"
        ;
#endif

#define MODULE_FLAG_LOADED              0x0001
#define MODULE_FLAG_NEED_DEPS           0x0002
/* "was seen in modules.dep": */
#define MODULE_FLAG_FOUND_IN_MODDEP     0x0004
#define MODULE_FLAG_BLACKLISTED         0x0008

struct module_entry { /* I'll call it ME. */
        unsigned flags;
        char *modname; /* stripped of /path/, .ext and s/-/_/g */
        const char *probed_name; /* verbatim as seen on cmdline */
        char *options; /* options from config files */
        llist_t *realnames; /* strings. if this module is an alias, */
        /* real module name is one of these. */
//Can there really be more than one? Example from real kernel?
        llist_t *deps; /* strings. modules we depend on */
};

#define DB_HASH_SIZE 256

struct globals {
        llist_t *probes; /* MEs of module(s) requested on cmdline */
        char *cmdline_mopts; /* module options from cmdline */
        int num_unresolved_deps;
        /* bool. "Did we have 'symbol:FOO' requested on cmdline?" */
        smallint need_symbols;
        struct utsname uts;
        llist_t *db[DB_HASH_SIZE]; /* MEs of all modules ever seen (caching for speed) */
} FIX_ALIASING;
#define G (*ptr_to_globals)
#define INIT_G() do { \
        SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
} while (0)


static int read_config(const char *path);

static char *gather_options_str(char *opts, const char *append)
{
        /* Speed-optimized. We call gather_options_str many times. */
        if (append) {
                if (opts == NULL) {
                        opts = xstrdup(append);
                } else {
                        int optlen = strlen(opts);
                        opts = xrealloc(opts, optlen + strlen(append) + 2);
                        sprintf(opts + optlen, " %s", append);
                }
        }
        return opts;
}

/* These three functions called many times, optimizing for speed.
 * Users reported minute-long delays when they runn iptables repeatedly
 * (iptables use modprobe to install needed kernel modules).
 */
static struct module_entry *helper_get_module(const char *module, int create)
{
        char modname[MODULE_NAME_LEN];
        struct module_entry *e;
        llist_t *l;
        unsigned i;
        unsigned hash;

        filename2modname(module, modname);

        hash = 0;
        for (i = 0; modname[i]; i++)
                hash = ((hash << 5) + hash) + modname[i];
        hash %= DB_HASH_SIZE;

        for (l = G.db[hash]; l; l = l->link) {
                e = (struct module_entry *) l->data;
                if (strcmp(e->modname, modname) == 0)
                        return e;
        }
        if (!create)
                return NULL;

        e = xzalloc(sizeof(*e));
        e->modname = xstrdup(modname);
        llist_add_to(&G.db[hash], e);

        return e;
}
static ALWAYS_INLINE struct module_entry *get_or_add_modentry(const char *module)
{
        return helper_get_module(module, 1);
}
/* So far this function always gets a module pathname, never an alias name.
 * The crucial difference is that pathname needs dirname stripping,
 * while alias name must NOT do it!
 * Testcase where dirname stripping is likely to go wrong: "modprobe devname:snd/timer"
 */
static ALWAYS_INLINE struct module_entry *get_modentry(const char *pathname)
{
        return helper_get_module(bb_get_last_path_component_nostrip(pathname), 0);
}

static void add_probe(const char *name)
{
        struct module_entry *m;

        m = get_or_add_modentry(name);
        if (!(option_mask32 & (OPT_REMOVE | OPT_SHOW_DEPS))
         && (m->flags & MODULE_FLAG_LOADED)
        ) {
                DBG("skipping %s, it is already loaded", name);
                return;
        }

        DBG("queuing %s", name);
        m->probed_name = name;
        m->flags |= MODULE_FLAG_NEED_DEPS;
        llist_add_to_end(&G.probes, m);
        G.num_unresolved_deps++;
        if (ENABLE_FEATURE_MODUTILS_SYMBOLS
         && strncmp(m->modname, "symbol:", 7) == 0
        ) {
                G.need_symbols = 1;
        }
}

static int FAST_FUNC config_file_action(const char *filename,
                                        struct stat *statbuf UNUSED_PARAM,
                                        void *userdata UNUSED_PARAM,
                                        int depth UNUSED_PARAM)
{
        char *tokens[3];
        parser_t *p;
        struct module_entry *m;
        int rc = TRUE;

        if (bb_basename(filename)[0] == '.')
                goto error;

        p = config_open2(filename, fopen_for_read);
        if (p == NULL) {
                rc = FALSE;
                goto error;
        }

        while (config_read(p, tokens, 3, 2, "# \t", PARSE_NORMAL)) {
//Use index_in_strings?
                if (strcmp(tokens[0], "alias") == 0) {
                        /* alias <wildcard> <modulename> */
                        llist_t *l;
                        char wildcard[MODULE_NAME_LEN];
                        char *rmod;

                        if (tokens[2] == NULL)
                                continue;
                        filename2modname(tokens[1], wildcard);

                        for (l = G.probes; l; l = l->link) {
                                m = (struct module_entry *) l->data;
                                if (fnmatch(wildcard, m->modname, 0) != 0)
                                        continue;
                                rmod = filename2modname(tokens[2], NULL);
                                llist_add_to(&m->realnames, rmod);

                                if (m->flags & MODULE_FLAG_NEED_DEPS) {
                                        m->flags &= ~MODULE_FLAG_NEED_DEPS;
                                        G.num_unresolved_deps--;
                                }

                                m = get_or_add_modentry(rmod);
                                if (!(m->flags & MODULE_FLAG_NEED_DEPS)) {
                                        m->flags |= MODULE_FLAG_NEED_DEPS;
                                        G.num_unresolved_deps++;
                                }
                        }
                } else if (strcmp(tokens[0], "options") == 0) {
                        /* options <modulename> <option...> */
                        if (tokens[2] == NULL)
                                continue;
                        m = get_or_add_modentry(tokens[1]);
                        m->options = gather_options_str(m->options, tokens[2]);
                } else if (strcmp(tokens[0], "include") == 0) {
                        /* include <filename> */
                        read_config(tokens[1]);
                } else if (ENABLE_FEATURE_MODPROBE_BLACKLIST
                 && strcmp(tokens[0], "blacklist") == 0
                ) {
                        /* blacklist <modulename> */
                        get_or_add_modentry(tokens[1])->flags |= MODULE_FLAG_BLACKLISTED;
                }
        }
        config_close(p);
 error:
        return rc;
}

static int read_config(const char *path)
{
        return recursive_action(path, ACTION_RECURSE | ACTION_QUIET,
                                config_file_action, NULL, NULL, 1);
}

static const char *humanly_readable_name(struct module_entry *m)
{
        /* probed_name may be NULL. modname always exists. */
        return m->probed_name ? m->probed_name : m->modname;
}

static char *parse_and_add_kcmdline_module_options(char *options, const char *modulename)
{
        char *kcmdline_buf;
        char *kcmdline;
        char *kptr;
        int len;

        kcmdline_buf = xmalloc_open_read_close("/proc/cmdline", NULL);
        if (!kcmdline_buf)
                return options;

        kcmdline = kcmdline_buf;
        len = strlen(modulename);
        while ((kptr = strsep(&kcmdline, "\n\t ")) != NULL) {
                if (strncmp(modulename, kptr, len) != 0)
                        continue;
                kptr += len;
                if (*kptr != '.')
                        continue;
                /* It is "modulename.xxxx" */
                kptr++;
                if (strchr(kptr, '=') != NULL) {
                        /* It is "modulename.opt=[val]" */
                        options = gather_options_str(options, kptr);
                }
        }
        free(kcmdline_buf);

        return options;
}

/* Return: similar to bb_init_module:
 * 0 on success,
 * -errno on open/read error,
 * errno on init_module() error
 */
/* NB: INSMOD_OPT_SILENT bit suppresses ONLY non-existent modules,
 * not deleted ones (those are still listed in modules.dep).
 * module-init-tools version 3.4:
 * # modprobe bogus
 * FATAL: Module bogus not found. [exitcode 1]
 * # modprobe -q bogus            [silent, exitcode still 1]
 * but:
 * # rm kernel/drivers/net/dummy.ko
 * # modprobe -q dummy
 * FATAL: Could not open '/lib/modules/xxx/kernel/drivers/net/dummy.ko': No such file or directory
 * [exitcode 1]
 */
static int do_modprobe(struct module_entry *m)
{
        int rc, first;

        if (!(m->flags & MODULE_FLAG_FOUND_IN_MODDEP)) {
                if (!(option_mask32 & INSMOD_OPT_SILENT))
                        bb_error_msg("module %s not found in modules.dep",
                                humanly_readable_name(m));
                return -ENOENT;
        }
        DBG("do_modprob'ing %s", m->modname);

        if (!(option_mask32 & OPT_REMOVE))
                m->deps = llist_rev(m->deps);

        if (0) {
                llist_t *l;
                for (l = m->deps; l; l = l->link)
                        DBG("dep: %s", l->data);
        }

        first = 1;
        rc = 0;
        while (m->deps) {
                struct module_entry *m2;
                char *fn, *options;

                rc = 0;
                fn = llist_pop(&m->deps); /* we leak it */
                m2 = get_or_add_modentry(bb_get_last_path_component_nostrip(fn));

                if (option_mask32 & OPT_REMOVE) {
                        /* modprobe -r */
                        if (m2->flags & MODULE_FLAG_LOADED) {
                                rc = bb_delete_module(m2->modname, O_NONBLOCK | O_EXCL);
                                if (rc) {
                                        if (first) {
                                                bb_error_msg("can't unload module %s: %s",
                                                        humanly_readable_name(m2),
                                                        moderror(rc));
                                                break;
                                        }
                                } else {
                                        m2->flags &= ~MODULE_FLAG_LOADED;
                                }
                        }
                        /* do not error out if *deps* fail to unload */
                        first = 0;
                        continue;
                }

                options = m2->options;
                m2->options = NULL;
                options = parse_and_add_kcmdline_module_options(options, m2->modname);
                if (m == m2)
                        options = gather_options_str(options, G.cmdline_mopts);

                if (option_mask32 & OPT_SHOW_DEPS) {
                        printf(options ? "insmod %s/%s/%s %s\n"
                                        : "insmod %s/%s/%s\n",
                                CONFIG_DEFAULT_MODULES_DIR, G.uts.release, fn,
                                options);
                        free(options);
                        continue;
                }

                if (m2->flags & MODULE_FLAG_LOADED) {
                        DBG("%s is already loaded, skipping", fn);
                        free(options);
                        continue;
                }

                rc = bb_init_module(fn, options);
                DBG("loaded %s '%s', rc:%d", fn, options, rc);
                if (rc == EEXIST)
                        rc = 0;
                free(options);
                if (rc) {
                        bb_error_msg("can't load module %s (%s): %s",
                                humanly_readable_name(m2),
                                fn,
                                moderror(rc)
                        );
                        break;
                }
                m2->flags |= MODULE_FLAG_LOADED;
        }

        return rc;
}

static void load_modules_dep(void)
{
        struct module_entry *m;
        char *colon, *tokens[2];
        parser_t *p;

        /* Modprobe does not work at all without modules.dep,
         * even if the full module name is given. Returning error here
         * was making us later confuse user with this message:
         * "module /full/path/to/existing/file/module.ko not found".
         * It's better to die immediately, with good message.
         * xfopen_for_read provides that. */
        p = config_open2(CONFIG_DEFAULT_DEPMOD_FILE, xfopen_for_read);

        while (G.num_unresolved_deps
         && config_read(p, tokens, 2, 1, "# \t", PARSE_NORMAL)
        ) {
                colon = last_char_is(tokens[0], ':');
                if (colon == NULL)
                        continue;
                *colon = '\0';

                m = get_modentry(tokens[0]);
                if (m == NULL)
                        continue;

                /* Optimization... */
                if ((m->flags & MODULE_FLAG_LOADED)
                 && !(option_mask32 & (OPT_REMOVE | OPT_SHOW_DEPS))
                ) {
                        DBG("skip deps of %s, it's already loaded", tokens[0]);
                        continue;
                }

                m->flags |= MODULE_FLAG_FOUND_IN_MODDEP;
                if ((m->flags & MODULE_FLAG_NEED_DEPS) && (m->deps == NULL)) {
                        G.num_unresolved_deps--;
                        llist_add_to(&m->deps, xstrdup(tokens[0]));
                        if (tokens[1])
                                string_to_llist(tokens[1], &m->deps, " \t");
                } else
                        DBG("skipping dep line");
        }
        config_close(p);
}

int modprobe_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int modprobe_main(int argc UNUSED_PARAM, char **argv)
{
        int rc;
        unsigned opt;
        struct module_entry *me;

        INIT_G();

        IF_LONG_OPTS(applet_long_options = modprobe_longopts;)
        opt_complementary = MODPROBE_COMPLEMENTARY;
        opt = getopt32(argv, INSMOD_OPTS MODPROBE_OPTS INSMOD_ARGS);
        argv += optind;

        /* Goto modules location */
        xchdir(CONFIG_DEFAULT_MODULES_DIR);
        uname(&G.uts);
        xchdir(G.uts.release);

        if (opt & OPT_LIST_ONLY) {
                int i;
                char *colon, *tokens[2];
                parser_t *p = config_open2(CONFIG_DEFAULT_DEPMOD_FILE, xfopen_for_read);

                for (i = 0; argv[i]; i++)
                        replace(argv[i], '-', '_');

                while (config_read(p, tokens, 2, 1, "# \t", PARSE_NORMAL)) {
                        colon = last_char_is(tokens[0], ':');
                        if (!colon)
                                continue;
                        *colon = '\0';
                        if (!argv[0])
                                puts(tokens[0]);
                        else {
                                char name[MODULE_NAME_LEN];
                                filename2modname(
                                        bb_get_last_path_component_nostrip(tokens[0]),
                                        name
                                );
                                for (i = 0; argv[i]; i++) {
                                        if (fnmatch(argv[i], name, 0) == 0) {
                                                puts(tokens[0]);
                                        }
                                }
                        }
                }
                return EXIT_SUCCESS;
        }

        /* Yes, for some reason -l ignores -s... */
        if (opt & INSMOD_OPT_SYSLOG)
                logmode = LOGMODE_SYSLOG;

        if (!argv[0]) {
                if (opt & OPT_REMOVE) {
                        /* "modprobe -r" (w/o params).
                         * "If name is NULL, all unused modules marked
                         * autoclean will be removed".
                         */
                        if (bb_delete_module(NULL, O_NONBLOCK | O_EXCL) != 0)
                                bb_perror_msg_and_die("rmmod");
                }
                return EXIT_SUCCESS;
        }

        /* Retrieve module names of already loaded modules */
        {
                char *s;
                parser_t *parser = config_open2("/proc/modules", fopen_for_read);
                while (config_read(parser, &s, 1, 1, "# \t", PARSE_NORMAL & ~PARSE_GREEDY))
                        get_or_add_modentry(s)->flags |= MODULE_FLAG_LOADED;
                config_close(parser);
        }

        if (opt & (OPT_INSERT_ALL | OPT_REMOVE)) {
                /* Each argument is a module name */
                do {
                        DBG("adding module %s", *argv);
                        add_probe(*argv++);
                } while (*argv);
        } else {
                /* First argument is module name, rest are parameters */
                DBG("probing just module %s", *argv);
                add_probe(argv[0]);
                G.cmdline_mopts = parse_cmdline_module_options(argv, /*quote_spaces:*/ 1);
        }

        /* Happens if all requested modules are already loaded */
        if (G.probes == NULL)
                return EXIT_SUCCESS;

        read_config("/etc/modprobe.conf");
        read_config("/etc/modprobe.d");
        if (ENABLE_FEATURE_MODUTILS_SYMBOLS && G.need_symbols)
                read_config("modules.symbols");
        load_modules_dep();
        if (ENABLE_FEATURE_MODUTILS_ALIAS && G.num_unresolved_deps) {
                read_config("modules.alias");
                load_modules_dep();
        }

        rc = 0;
        while ((me = llist_pop(&G.probes)) != NULL) {
                if (me->realnames == NULL) {
                        DBG("probing by module name");
                        /* This is not an alias. Literal names are blacklisted
                         * only if '-b' is given.
                         */
                        if (!(opt & OPT_BLACKLIST)
                         || !(me->flags & MODULE_FLAG_BLACKLISTED)
                        ) {
                                rc |= do_modprobe(me);
                        }
                        continue;
                }

                /* Probe all real names for the alias */
                do {
                        char *realname = llist_pop(&me->realnames);
                        struct module_entry *m2;

                        DBG("probing alias %s by realname %s", me->modname, realname);
                        m2 = get_or_add_modentry(realname);
                        if (!(m2->flags & MODULE_FLAG_BLACKLISTED)
                         && (!(m2->flags & MODULE_FLAG_LOADED)
                            || (opt & (OPT_REMOVE | OPT_SHOW_DEPS)))
                        ) {
//TODO: we can pass "me" as 2nd param to do_modprobe,
//and make do_modprobe emit more meaningful error messages
//with alias name included, not just module name alias resolves to.
                                rc |= do_modprobe(m2);
                        }
                        free(realname);
                } while (me->realnames != NULL);
        }

        return (rc != 0);
}