/* vi: set sw=4 ts=4: */
/*
 * simplified modprobe
 *
 * Copyright (c) 2008 Vladimir Dronnikov
 * Copyright (c) 2008 Bernhard Reutner-Fischer (initial depmod code)
 *
 * Licensed under GPLv2, see file LICENSE in this source tree.
 */

/* modprobe-small configs are defined in Config.src to ensure better
 * "make config" order */

//applet:IF_LSMOD(   IF_MODPROBE_SMALL(APPLET_NOEXEC( lsmod,    lsmod,    BB_DIR_SBIN, BB_SUID_DROP, lsmod   )))
//applet:IF_MODPROBE(IF_MODPROBE_SMALL(APPLET_NOEXEC( modprobe, modprobe, BB_DIR_SBIN, BB_SUID_DROP, modprobe)))
//                                     APPLET_ODDNAME:name      main      location     suid_type     help
//applet:IF_DEPMOD(  IF_MODPROBE_SMALL(APPLET_ODDNAME(depmod,   modprobe, BB_DIR_SBIN, BB_SUID_DROP, depmod  )))
//applet:IF_INSMOD(  IF_MODPROBE_SMALL(APPLET_NOEXEC( insmod,   modprobe, BB_DIR_SBIN, BB_SUID_DROP, insmod  )))
//applet:IF_RMMOD(   IF_MODPROBE_SMALL(APPLET_NOEXEC( rmmod,    modprobe, BB_DIR_SBIN, BB_SUID_DROP, rmmod   )))
/* noexec speeds up boot with many modules loaded (need SH_STANDALONE=y) */
/* I measured about ~5 times faster insmod */
/* depmod is not noexec, it runs longer and benefits from memory trimming via exec */

//kbuild:lib-$(CONFIG_MODPROBE_SMALL) += modprobe-small.o

#include "libbb.h"
/* After libbb.h, since it needs sys/types.h on some systems */
#include <sys/utsname.h> /* uname() */
#include <fnmatch.h>
#include <sys/syscall.h>

#define init_module(mod, len, opts) syscall(__NR_init_module, mod, len, opts)
#define delete_module(mod, flags) syscall(__NR_delete_module, mod, flags)
#ifdef __NR_finit_module
# define finit_module(fd, uargs, flags) syscall(__NR_finit_module, fd, uargs, flags)
#endif
/* linux/include/linux/module.h has limit of 64 chars on module names */
#undef MODULE_NAME_LEN
#define MODULE_NAME_LEN 64


#if 1
# define dbg1_error_msg(...) ((void)0)
# define dbg2_error_msg(...) ((void)0)
#else
# define dbg1_error_msg(...) bb_error_msg(__VA_ARGS__)
# define dbg2_error_msg(...) bb_error_msg(__VA_ARGS__)
#endif

#define DEPFILE_BB CONFIG_DEFAULT_DEPMOD_FILE".bb"

//usage:#if ENABLE_MODPROBE_SMALL

//usage:#define lsmod_trivial_usage
//usage:       ""
//usage:#define lsmod_full_usage "\n\n"
//usage:       "List loaded kernel modules"

//usage:#endif

#if ENABLE_LSMOD
int lsmod_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int lsmod_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
{
        xprint_and_close_file(xfopen_for_read("/proc/modules"));
        return EXIT_SUCCESS;
}
#endif

/* Num of applets that use modprobe_main() entry point. */
/* lsmod is not here. */
#define MOD_APPLET_CNT (ENABLE_MODPROBE + ENABLE_DEPMOD + ENABLE_INSMOD + ENABLE_RMMOD)

/* Do not bother if MODPROBE_SMALL=y but no applets selected. */
/* The rest of the file is in this if block. */
#if MOD_APPLET_CNT > 0

#define ONLY_APPLET (MOD_APPLET_CNT == 1)
#define is_modprobe (ENABLE_MODPROBE && (ONLY_APPLET || applet_name[0] == 'm'))
#define is_depmod   (ENABLE_DEPMOD   && (ONLY_APPLET || applet_name[0] == 'd'))
#define is_insmod   (ENABLE_INSMOD   && (ONLY_APPLET || applet_name[0] == 'i'))
#define is_rmmod    (ENABLE_RMMOD    && (ONLY_APPLET || applet_name[0] == 'r'))

enum {
        DEPMOD_OPT_n = (1 << 0), /* dry-run, print to stdout */
        OPT_q = (1 << 0), /* be quiet */
        OPT_r = (1 << 1), /* module removal instead of loading */
};

typedef struct module_info {
        char *pathname;
        char *aliases;
        char *deps;
        smallint open_read_failed;
} module_info;

/*
 * GLOBALS
 */
struct globals {
        module_info *modinfo;
        char *module_load_options;
        smallint dep_bb_seen;
        smallint wrote_dep_bb_ok;
        unsigned module_count;
        int module_found_idx;
        unsigned stringbuf_idx;
        unsigned stringbuf_size;
        char *stringbuf; /* some modules have lots of stuff */
        /* for example, drivers/media/video/saa7134/saa7134.ko */
        /* therefore having a fixed biggish buffer is not wise */
};
#define G (*ptr_to_globals)
#define modinfo             (G.modinfo            )
#define dep_bb_seen         (G.dep_bb_seen        )
#define wrote_dep_bb_ok     (G.wrote_dep_bb_ok    )
#define module_count        (G.module_count       )
#define module_found_idx    (G.module_found_idx   )
#define module_load_options (G.module_load_options)
#define stringbuf_idx       (G.stringbuf_idx      )
#define stringbuf_size      (G.stringbuf_size     )
#define stringbuf           (G.stringbuf          )
#define INIT_G() do { \
        SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
} while (0)

static void append(const char *s)
{
        unsigned len = strlen(s);
        if (stringbuf_idx + len + 15 > stringbuf_size) {
                stringbuf_size = stringbuf_idx + len + 127;
                dbg2_error_msg("grow stringbuf to %u", stringbuf_size);
                stringbuf = xrealloc(stringbuf, stringbuf_size);
        }
        memcpy(stringbuf + stringbuf_idx, s, len);
        stringbuf_idx += len;
}

static void appendc(char c)
{
        /* We appendc() only after append(), + 15 trick in append()
         * makes it unnecessary to check for overflow here */
        stringbuf[stringbuf_idx++] = c;
}

static void bksp(void)
{
        if (stringbuf_idx)
                stringbuf_idx--;
}

static void reset_stringbuf(void)
{
        stringbuf_idx = 0;
}

static char* copy_stringbuf(void)
{
        char *copy = xzalloc(stringbuf_idx + 1); /* terminating NUL */
        return memcpy(copy, stringbuf, stringbuf_idx);
}

static char* find_keyword(char *ptr, size_t len, const char *word)
{
        if (!ptr) /* happens if xmalloc_open_zipped_read_close cannot read it */
                return NULL;

        len -= strlen(word) - 1;
        while ((ssize_t)len > 0) {
                char *old = ptr;
                char *after_word;

                /* search for the first char in word */
                ptr = memchr(ptr, word[0], len);
                if (ptr == NULL) /* no occurrence left, done */
                        break;
                after_word = is_prefixed_with(ptr, word);
                if (after_word)
                        return after_word; /* found, return ptr past it */
                ++ptr;
                len -= (ptr - old);
        }
        return NULL;
}

static void replace(char *s, char what, char with)
{
        while (*s) {
                if (what == *s)
                        *s = with;
                ++s;
        }
}

static char *filename2modname(const char *filename, char *modname)
{
        int i;
        const char *from;

        // Disabled since otherwise "modprobe dir/name" would work
        // as if it is "modprobe name". It is unclear why
        // 'basenamization' was here in the first place.
        //from = bb_get_last_path_component_nostrip(filename);
        from = filename;
        for (i = 0; i < (MODULE_NAME_LEN-1) && from[i] != '\0' && from[i] != '.'; i++)
                modname[i] = (from[i] == '-') ? '_' : from[i];
        modname[i] = '\0';

        return modname;
}

static int pathname_matches_modname(const char *pathname, const char *modname)
{
        int r;
        char name[MODULE_NAME_LEN];
        filename2modname(bb_get_last_path_component_nostrip(pathname), name);
        r = (strcmp(name, modname) == 0);
        return r;
}

/* Take "word word", return malloced "word",NUL,"word",NUL,NUL */
static char* str_2_list(const char *str)
{
        int len = strlen(str) + 1;
        char *dst = xmalloc(len + 1);

        dst[len] = '\0';
        memcpy(dst, str, len);
//TODO: protect against 2+ spaces: "word  word"
        replace(dst, ' ', '\0');
        return dst;
}

/* We use error numbers in a loose translation... */
static const char *moderror(int err)
{
        switch (err) {
        case ENOEXEC:
                return "invalid module format";
        case ENOENT:
                return "unknown symbol in module or invalid parameter";
        case ESRCH:
                return "module has wrong symbol version";
        case EINVAL: /* "invalid parameter" */
                return "unknown symbol in module or invalid parameter"
                + sizeof("unknown symbol in module or");
        default:
                return strerror(err);
        }
}

static int load_module(const char *fname, const char *options)
{
#if 1
        int r;
        size_t len = MAXINT(ssize_t);
        char *module_image;

        if (!options)
                options = "";

        dbg1_error_msg("load_module('%s','%s')", fname, options);

        /*
         * First we try finit_module if available.  Some kernels are configured
         * to only allow loading of modules off of secure storage (like a read-
         * only rootfs) which needs the finit_module call.  If it fails, we fall
         * back to normal module loading to support compressed modules.
         */
        r = 1;
# ifdef __NR_finit_module
        {
                int fd = open(fname, O_RDONLY | O_CLOEXEC);
                if (fd >= 0) {
                        r = finit_module(fd, options, 0) != 0;
                        close(fd);
                }
        }
# endif
        if (r != 0) {
                module_image = xmalloc_open_zipped_read_close(fname, &len);
                r = (!module_image || init_module(module_image, len, options) != 0);
                free(module_image);
        }

        dbg1_error_msg("load_module:%d", r);
        return r; /* 0 = success */
#else
        /* For testing */
        dbg1_error_msg("load_module('%s','%s')", fname, options);
        return 1;
#endif
}

/* Returns !0 if open/read was unsuccessful */
static int parse_module(module_info *info, const char *pathname)
{
        char *module_image;
        char *ptr;
        size_t len;
        size_t pos;
        dbg1_error_msg("parse_module('%s')", pathname);

        /* Read (possibly compressed) module */
        errno = 0;
        len = 64 * 1024 * 1024; /* 64 Mb at most */
        module_image = xmalloc_open_zipped_read_close(pathname, &len);
        /* module_image == NULL is ok here, find_keyword handles it */
//TODO: optimize redundant module body reads

        /* "alias1 symbol:sym1 alias2 symbol:sym2" */
        reset_stringbuf();
        pos = 0;
        while (1) {
                unsigned start = stringbuf_idx;
                ptr = find_keyword(module_image + pos, len - pos, "alias=");
                if (!ptr) {
                        ptr = find_keyword(module_image + pos, len - pos, "__ksymtab_");
                        if (!ptr)
                                break;
                        /* DOCME: __ksymtab_gpl and __ksymtab_strings occur
                         * in many modules. What do they mean? */
                        if (strcmp(ptr, "gpl") == 0 || strcmp(ptr, "strings") == 0)
                                goto skip;
                        dbg2_error_msg("alias:'symbol:%s'", ptr);
                        append("symbol:");
                } else {
                        dbg2_error_msg("alias:'%s'", ptr);
                }
                append(ptr);
                appendc(' ');
                /*
                 * Don't add redundant aliases, such as:
                 * libcrc32c.ko symbol:crc32c symbol:crc32c
                 */
                if (start) { /* "if we aren't the first alias" */
                        char *found, *last;
                        stringbuf[stringbuf_idx] = '\0';
                        last = stringbuf + start;
                        /*
                         * String at last-1 is " symbol:crc32c "
                         * (with both leading and trailing spaces).
                         */
                        if (strncmp(stringbuf, last, stringbuf_idx - start) == 0)
                                /* First alias matches us */
                                found = stringbuf;
                        else
                                /* Does any other alias match? */
                                found = strstr(stringbuf, last-1);
                        if (found < last-1) {
                                /* There is absolutely the same string before us */
                                dbg2_error_msg("redundant:'%s'", last);
                                stringbuf_idx = start;
                                goto skip;
                        }
                }
 skip:
                pos = (ptr - module_image);
        }
        bksp(); /* remove last ' ' */
        info->aliases = copy_stringbuf();
        replace(info->aliases, '-', '_');

        /* "dependency1 depandency2" */
        reset_stringbuf();
        ptr = find_keyword(module_image, len, "depends=");
        if (ptr && *ptr) {
                replace(ptr, ',', ' ');
                replace(ptr, '-', '_');
                dbg2_error_msg("dep:'%s'", ptr);
                append(ptr);
        }
        free(module_image);
        info->deps = copy_stringbuf();

        info->open_read_failed = (module_image == NULL);
        return info->open_read_failed;
}

static FAST_FUNC int fileAction(const char *pathname,
                struct stat *sb UNUSED_PARAM,
                void *modname_to_match,
                int depth UNUSED_PARAM)
{
        int cur;
        const char *fname;
        bool is_remove = (ENABLE_RMMOD && ONLY_APPLET)
                || ((ENABLE_RMMOD || ENABLE_MODPROBE) && (option_mask32 & OPT_r));

        pathname += 2; /* skip "./" */
        fname = bb_get_last_path_component_nostrip(pathname);
        if (!strrstr(fname, ".ko")) {
                dbg1_error_msg("'%s' is not a module", pathname);
                return TRUE; /* not a module, continue search */
        }

        cur = module_count++;
        modinfo = xrealloc_vector(modinfo, 12, cur);
        modinfo[cur].pathname = xstrdup(pathname);
        /*modinfo[cur].aliases = NULL; - xrealloc_vector did it */
        /*modinfo[cur+1].pathname = NULL;*/

        if (!pathname_matches_modname(fname, modname_to_match)) {
                dbg1_error_msg("'%s' module name doesn't match", pathname);
                return TRUE; /* module name doesn't match, continue search */
        }

        dbg1_error_msg("'%s' module name matches", pathname);
        module_found_idx = cur;
        if (parse_module(&modinfo[cur], pathname) != 0)
                return TRUE; /* failed to open/read it, no point in trying loading */

        if (!is_remove) {
                if (load_module(pathname, module_load_options) == 0) {
                        /* Load was successful, there is nothing else to do.
                         * This can happen ONLY for "top-level" module load,
                         * not a dep, because deps don't do dirscan. */
                        exit(EXIT_SUCCESS);
                }
        }

        return TRUE;
}

static int load_dep_bb(void)
{
        char *line;
        FILE *fp = fopen_for_read(DEPFILE_BB);

        if (!fp)
                return 0;

        dep_bb_seen = 1;
        dbg1_error_msg("loading "DEPFILE_BB);

        /* Why? There is a rare scenario: we did not find modprobe.dep.bb,
         * we scanned the dir and found no module by name, then we search
         * for alias (full scan), and we decided to generate modprobe.dep.bb.
         * But we see modprobe.dep.bb.new! Other modprobe is at work!
         * We wait and other modprobe renames it to modprobe.dep.bb.
         * Now we can use it.
         * But we already have modinfo[] filled, and "module_count = 0"
         * makes us start anew. Yes, we leak modinfo[].xxx pointers -
         * there is not much of data there anyway. */
        module_count = 0;
        memset(&modinfo[0], 0, sizeof(modinfo[0]));

        while ((line = xmalloc_fgetline(fp)) != NULL) {
                char* space;
                char* linebuf;
                int cur;

                if (!line[0]) {
                        free(line);
                        continue;
                }
                space = strchrnul(line, ' ');
                cur = module_count++;
                modinfo = xrealloc_vector(modinfo, 12, cur);
                /*modinfo[cur+1].pathname = NULL; - xrealloc_vector did it */
                modinfo[cur].pathname = line; /* we take ownership of malloced block here */
                if (*space)
                        *space++ = '\0';
                modinfo[cur].aliases = space;
                linebuf = xmalloc_fgetline(fp);
                modinfo[cur].deps = linebuf ? linebuf : xzalloc(1);
                if (modinfo[cur].deps[0]) {
                        /* deps are not "", so next line must be empty */
                        line = xmalloc_fgetline(fp);
                        /* Refuse to work with damaged config file */
                        if (line && line[0])
                                bb_error_msg_and_die("error in %s at '%s'", DEPFILE_BB, line);
                        free(line);
                }
        }
        return 1;
}

static int start_dep_bb_writeout(void)
{
        int fd;

        /* depmod -n: write result to stdout */
        if (is_depmod && (option_mask32 & DEPMOD_OPT_n))
                return STDOUT_FILENO;

        fd = open(DEPFILE_BB".new", O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, 0644);
        if (fd < 0) {
                if (errno == EEXIST) {
                        int count = 5 * 20;
                        dbg1_error_msg(DEPFILE_BB".new exists, waiting for "DEPFILE_BB);
                        while (1) {
                                usleep(1000*1000 / 20);
                                if (load_dep_bb()) {
                                        dbg1_error_msg(DEPFILE_BB" appeared");
                                        return -2; /* magic number */
                                }
                                if (!--count)
                                        break;
                        }
                        bb_error_msg("deleting stale %s", DEPFILE_BB".new");
                        fd = open_or_warn(DEPFILE_BB".new", O_WRONLY | O_CREAT | O_TRUNC);
                }
        }
        dbg1_error_msg("opened "DEPFILE_BB".new:%d", fd);
        return fd;
}

static void write_out_dep_bb(int fd)
{
        int i;
        FILE *fp;

        /* We want good error reporting. fdprintf is not good enough. */
        fp = xfdopen_for_write(fd);
        i = 0;
        while (modinfo[i].pathname) {
                fprintf(fp, "%s%s%s\n" "%s%s\n",
                        modinfo[i].pathname, modinfo[i].aliases[0] ? " " : "", modinfo[i].aliases,
                        modinfo[i].deps, modinfo[i].deps[0] ? "\n" : "");
                i++;
        }
        /* Badly formatted depfile is a no-no. Be paranoid. */
        errno = 0;
        if (ferror(fp) | fclose(fp)) /* | instead of || is intended */
                goto err;

        if (fd == STDOUT_FILENO) /* it was depmod -n */
                goto ok;

        if (rename(DEPFILE_BB".new", DEPFILE_BB) != 0) {
 err:
                bb_perror_msg("can't create '%s'", DEPFILE_BB);
                unlink(DEPFILE_BB".new");
        } else {
 ok:
                wrote_dep_bb_ok = 1;
                dbg1_error_msg("created "DEPFILE_BB);
        }
}

static module_info** find_alias(const char *alias)
{
        int i;
        int dep_bb_fd;
        int infoidx;
        module_info **infovec;
        dbg1_error_msg("find_alias('%s')", alias);

 try_again:
        /* First try to find by name (cheaper) */
        i = 0;
        while (modinfo[i].pathname) {
                if (pathname_matches_modname(modinfo[i].pathname, alias)) {
                        dbg1_error_msg("found '%s' in module '%s'",
                                        alias, modinfo[i].pathname);
                        if (!modinfo[i].aliases) {
                                parse_module(&modinfo[i], modinfo[i].pathname);
                        }
                        infovec = xzalloc(2 * sizeof(infovec[0]));
                        infovec[0] = &modinfo[i];
                        return infovec;
                }
                i++;
        }

        /* Ok, we definitely have to scan module bodies. This is a good
         * moment to generate modprobe.dep.bb, if it does not exist yet */
        dep_bb_fd = dep_bb_seen ? -1 : start_dep_bb_writeout();
        if (dep_bb_fd == -2) /* modprobe.dep.bb appeared? */
                goto try_again;

        /* Scan all module bodies, extract modinfo (it contains aliases) */
        i = 0;
        infoidx = 0;
        infovec = NULL;
        while (modinfo[i].pathname) {
                char *desc, *s;
                if (!modinfo[i].aliases) {
                        parse_module(&modinfo[i], modinfo[i].pathname);
                }
                /* "alias1 symbol:sym1 alias2 symbol:sym2" */
                desc = str_2_list(modinfo[i].aliases);
                /* Does matching substring exist? */
                for (s = desc; *s; s += strlen(s) + 1) {
                        /* Aliases in module bodies can be defined with
                         * shell patterns. Example:
                         * "pci:v000010DEd000000D9sv*sd*bc*sc*i*".
                         * Plain strcmp() won't catch that */
                        if (fnmatch(s, alias, 0) == 0) {
                                dbg1_error_msg("found alias '%s' in module '%s'",
                                                alias, modinfo[i].pathname);
                                infovec = xrealloc_vector(infovec, 1, infoidx);
                                infovec[infoidx++] = &modinfo[i];
                                break;
                        }
                }
                free(desc);
                i++;
        }

        /* Create module.dep.bb if needed */
        if (dep_bb_fd >= 0) {
                write_out_dep_bb(dep_bb_fd);
        }

        dbg1_error_msg("find_alias '%s' returns %d results", alias, infoidx);
        return infovec;
}

#if ENABLE_FEATURE_MODPROBE_SMALL_CHECK_ALREADY_LOADED
// TODO: open only once, invent config_rewind()
static int already_loaded(const char *name)
{
        int ret;
        char *line;
        FILE *fp;

        ret = 5 * 2;
 again:
        fp = fopen_for_read("/proc/modules");
        if (!fp)
                return 0;
        while ((line = xmalloc_fgetline(fp)) != NULL) {
                char *live;
                char *after_name;

                // Examples from kernel 3.14.6:
                //pcspkr 12718 0 - Live 0xffffffffa017e000
                //snd_timer 28690 2 snd_seq,snd_pcm, Live 0xffffffffa025e000
                //i915 801405 2 - Live 0xffffffffa0096000
                after_name = is_prefixed_with(line, name);
                if (!after_name || *after_name != ' ') {
                        free(line);
                        continue;
                }
                live = strstr(line, " Live");
                free(line);
                if (!live) {
                        /* State can be Unloading, Loading, or Live.
                         * modprobe must not return prematurely if we see "Loading":
                         * it can cause further programs to assume load completed,
                         * but it did not (yet)!
                         * Wait up to 5*20 ms for it to resolve.
                         */
                        ret -= 2;
                        if (ret == 0)
                                break;  /* huh? report as "not loaded" */
                        fclose(fp);
                        usleep(20*1000);
                        goto again;
                }
                ret = 1;
                break;
        }
        fclose(fp);

        return ret & 1;
}
#else
#define already_loaded(name) 0
#endif

static int rmmod(const char *filename)
{
        int r;
        char modname[MODULE_NAME_LEN];

        filename2modname(filename, modname);
        r = delete_module(modname, O_NONBLOCK | O_EXCL);
        dbg1_error_msg("delete_module('%s', O_NONBLOCK | O_EXCL):%d", modname, r);
        if (r != 0 && !(option_mask32 & OPT_q)) {
                bb_perror_msg("remove '%s'", modname);
        }
        return r;
}

/*
 * Given modules definition and module name (or alias, or symbol)
 * load/remove the module respecting dependencies.
 * NB: also called by depmod with bogus name "/",
 * just in order to force modprobe.dep.bb creation.
*/
#if !ENABLE_FEATURE_CMDLINE_MODULE_OPTIONS
#define process_module(a,b) process_module(a)
#define cmdline_options ""
#endif
static int process_module(char *name, const char *cmdline_options)
{
        char *s, *deps, *options;
        module_info **infovec;
        module_info *info;
        int infoidx;
        bool is_remove = (ENABLE_RMMOD && ONLY_APPLET)
                || ((ENABLE_RMMOD || ENABLE_MODPROBE) && (option_mask32 & OPT_r));
        int exitcode = EXIT_SUCCESS;

        dbg1_error_msg("process_module('%s','%s')", name, cmdline_options);

        replace(name, '-', '_');

        dbg1_error_msg("already_loaded:%d is_remove:%d", already_loaded(name), is_remove);

        if (is_rmmod) {
                /* Does not remove dependencies, no need to scan, just remove.
                 * (compat note: this allows and strips .ko suffix)
                 */
                rmmod(name);
                return EXIT_SUCCESS;
        }

        /*
         * We used to have "is_remove != already_loaded(name)" check here, but
         *  modprobe -r pci:v00008086d00007010sv00000000sd00000000bc01sc01i80
         * won't unload modules (there are more than one)
         * which have this alias.
         */
        if (!is_remove && already_loaded(name)) {
                dbg1_error_msg("nothing to do for '%s'", name);
                return EXIT_SUCCESS;
        }

        options = NULL;
        if (!is_remove) {
                char *opt_filename = xasprintf("/etc/modules/%s", name);
                options = xmalloc_open_read_close(opt_filename, NULL);
                if (options)
                        replace(options, '\n', ' ');
#if ENABLE_FEATURE_CMDLINE_MODULE_OPTIONS
                if (cmdline_options) {
                        /* NB: cmdline_options always have one leading ' '
                         * (see main()), we remove it here */
                        char *op = xasprintf(options ? "%s %s" : "%s %s" + 3,
                                                cmdline_options + 1, options);
                        free(options);
                        options = op;
                }
#endif
                free(opt_filename);
                module_load_options = options;
                dbg1_error_msg("process_module('%s'): options:'%s'", name, options);
        }

        if (!module_count) {
                /* Scan module directory. This is done only once.
                 * It will attempt module load, and will exit(EXIT_SUCCESS)
                 * on success.
                 */
                module_found_idx = -1;
                recursive_action(".",
                        ACTION_RECURSE, /* flags */
                        fileAction, /* file action */
                        NULL, /* dir action */
                        name, /* user data */
                        0 /* depth */
                );
                dbg1_error_msg("dirscan complete");
                /* Module was not found, or load failed, or is_remove */
                if (module_found_idx >= 0) { /* module was found */
                        infovec = xzalloc(2 * sizeof(infovec[0]));
                        infovec[0] = &modinfo[module_found_idx];
                } else { /* search for alias, not a plain module name */
                        infovec = find_alias(name);
                }
        } else {
                infovec = find_alias(name);
        }

        if (!infovec) {
                /* both dirscan and find_alias found nothing */
                if (!is_remove && !is_depmod) { /* it wasn't rmmod or depmod */
                        bb_error_msg("module '%s' not found", name);
//TODO: _and_die()? or should we continue (un)loading modules listed on cmdline?
                        /* "modprobe non-existing-module; echo $?" must print 1 */
                        exitcode = EXIT_FAILURE;
                }
                goto ret;
        }

        /* There can be more than one module for the given alias. For example,
         * "pci:v00008086d00007010sv00000000sd00000000bc01sc01i80" matches
         * ata_piix because it has alias "pci:v00008086d00007010sv*sd*bc*sc*i*"
         * and ata_generic, it has alias "pci:v*d*sv*sd*bc01sc01i*"
         * Standard modprobe loads them both. We achieve it by returning
         * a *list* of modinfo pointers from find_alias().
         */

        /* modprobe -r? unload module(s) */
        if (is_remove) {
                infoidx = 0;
                while ((info = infovec[infoidx++]) != NULL) {
                        int r = rmmod(bb_get_last_path_component_nostrip(info->pathname));
                        if (r != 0) {
                                goto ret; /* error */
                        }
                }
                /* modprobe -r: we do not stop here -
                 * continue to unload modules on which the module depends:
                 * "-r --remove: option causes modprobe to remove a module.
                 * If the modules it depends on are also unused, modprobe
                 * will try to remove them, too."
                 */
        }

        infoidx = 0;
        while ((info = infovec[infoidx++]) != NULL) {
                /* Iterate thru dependencies, trying to (un)load them */
                deps = str_2_list(info->deps);
                for (s = deps; *s; s += strlen(s) + 1) {
                        //if (strcmp(name, s) != 0) // N.B. do loops exist?
                        dbg1_error_msg("recurse on dep '%s'", s);
                        process_module(s, NULL);
                        dbg1_error_msg("recurse on dep '%s' done", s);
                }
                free(deps);

                if (is_remove)
                        continue;

                /* We are modprobe: load it */
                if (options && strstr(options, "blacklist")) {
                        dbg1_error_msg("'%s': blacklisted", info->pathname);
                        continue;
                }
                if (info->open_read_failed) {
                        /* We already tried it, didn't work. Don't try load again */
                        exitcode = EXIT_FAILURE;
                        continue;
                }
                errno = 0;
                if (load_module(info->pathname, options) != 0) {
                        if (EEXIST != errno) {
                                bb_error_msg("'%s': %s",
                                        info->pathname,
                                        moderror(errno));
                        } else {
                                dbg1_error_msg("'%s': %s",
                                        info->pathname,
                                        moderror(errno));
                        }
                        exitcode = EXIT_FAILURE;
                }
        }
 ret:
        free(infovec);
        free(options);

        return exitcode;
}
#undef cmdline_options


/* For reference, module-init-tools v3.4 options:

# insmod
Usage: insmod filename [args]

# rmmod --help
Usage: rmmod [-fhswvV] modulename ...
 -f (or --force) forces a module unload, and may crash your
    machine. This requires the Forced Module Removal option
    when the kernel was compiled.
 -h (or --help) prints this help text
 -s (or --syslog) says use syslog, not stderr
 -v (or --verbose) enables more messages
 -V (or --version) prints the version code
 -w (or --wait) begins module removal even if it is used
    and will stop new users from accessing the module (so it
    should eventually fall to zero).

# modprobe
Usage: modprobe [-v] [-V] [-C config-file] [-d <dirname> ] [-n] [-i] [-q]
    [-b] [-o <modname>] [ --dump-modversions ] <modname> [parameters...]
modprobe -r [-n] [-i] [-v] <modulename> ...
modprobe -l -t <dirname> [ -a <modulename> ...]

# depmod --help
depmod 3.13 -- part of module-init-tools
depmod -[aA] [-n -e -v -q -V -r -u -w -m]
      [-b basedirectory] [forced_version]
depmod [-n -e -v -q -r -u -w] [-F kernelsyms] module1.ko module2.ko ...
If no arguments (except options) are given, "depmod -a" is assumed.
depmod will output a dependency list suitable for the modprobe utility.
Options:
    -a, --all           Probe all modules
    -A, --quick         Only does the work if there's a new module
    -e, --errsyms       Report not supplied symbols
    -m, --map           Create the legacy map files
    -n, --show          Write the dependency file on stdout only
    -P, --symbol-prefix Architecture symbol prefix
    -V, --version       Print the release version
    -v, --verbose       Enable verbose mode
    -w, --warn          Warn on duplicates
    -h, --help          Print this usage message
The following options are useful for people managing distributions:
    -b basedirectory
    --basedir basedirectory
                        Use an image of a module tree
    -F kernelsyms
    --filesyms kernelsyms
                        Use the file instead of the current kernel symbols
    -E Module.symvers
    --symvers Module.symvers
                        Use Module.symvers file to check symbol versions
*/

//usage:#if ENABLE_MODPROBE_SMALL

//usage:#define depmod_trivial_usage "[-n]"
//usage:#define depmod_full_usage "\n\n"
//usage:       "Generate modules.dep.bb"
//usage:     "\n"
//usage:     "\n        -n      Dry run: print file to stdout"

//usage:#define insmod_trivial_usage
//usage:        "FILE" IF_FEATURE_CMDLINE_MODULE_OPTIONS(" [SYMBOL=VALUE]...")
//usage:#define insmod_full_usage "\n\n"
//usage:       "Load kernel module"

//usage:#define rmmod_trivial_usage
//usage:       "MODULE..."
//usage:#define rmmod_full_usage "\n\n"
//usage:       "Unload kernel modules"

//usage:#define modprobe_trivial_usage
//usage:        "[-rq] MODULE" IF_FEATURE_CMDLINE_MODULE_OPTIONS(" [SYMBOL=VALUE]...")
//usage:#define modprobe_full_usage "\n\n"
//usage:       "        -r      Remove MODULE"
//usage:     "\n        -q      Quiet"

//usage:#endif

int modprobe_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int modprobe_main(int argc UNUSED_PARAM, char **argv)
{
#if ENABLE_MODPROBE || ENABLE_INSMOD || ENABLE_RMMOD
        int exitcode;
#endif
        struct utsname uts;
        IF_FEATURE_CMDLINE_MODULE_OPTIONS(char *options = NULL;)

        INIT_G();

        /* Prevent ugly corner cases with no modules at all */
        modinfo = xzalloc(sizeof(modinfo[0]));

        if ((MOD_APPLET_CNT == 2 && ENABLE_DEPMOD && ENABLE_MODPROBE)
         || is_depmod || is_modprobe
        ) {
                /* Goto modules directory */
                xchdir(CONFIG_DEFAULT_MODULES_DIR);
                uname(&uts); /* never fails */
        }

        /* depmod? */
        if (is_depmod) {
                /* Supported:
                 * -n: print result to stdout
                 * -a: process all modules (default)
                 * optional VERSION parameter
                 * Ignored:
                 * -A: do work only if a module is newer than depfile
                 * -e: report any symbols which a module needs
                 *  which are not supplied by other modules or the kernel
                 * -F FILE: System.map (symbols for -e)
                 * -q, -r, -u: noop
                 * Not supported:
                 * -b BASEDIR: (TODO!) modules are in
                 *  $BASEDIR/lib/modules/$VERSION
                 * -m: create legacy "modules.*map" files (deprecated; in
                 *  kmod's depmod, prints a warning message and continues)
                 * -v: human readable deps to stdout
                 * -V: version (don't want to support it - people may depend
                 *  on it as an indicator of "standard" depmod)
                 * -h: help (well duh)
                 * module1.o module2.o parameters (just ignored for now)
                 */
                getopt32(argv, "na" "AeF:qru" /* "b:vV", NULL */, NULL);
                argv += optind;
                /* if (argv[0] && argv[1]) bb_show_usage(); */
                /* Goto $VERSION directory */
                xchdir(argv[0] ? argv[0] : uts.release);
                /* Force full module scan by asking to find a bogus module.
                 * This will generate modules.dep.bb as a side effect. */
                process_module((char*)"/", NULL);
                return !wrote_dep_bb_ok;
        }

#if ENABLE_MODPROBE || ENABLE_INSMOD || ENABLE_RMMOD
        /* modprobe, insmod, rmmod require at least one argument */
        /* only -q (quiet) and -r (rmmod),
         * the rest are accepted and ignored (compat) */
        getopt32(argv, "^" "qrfsvwb" "\0" "-1");
        argv += optind;

        if (is_modprobe) {
                /* Goto $VERSION directory */
                xchdir(uts.release);
        }

        /* are we rmmod? -> simulate modprobe -r, but don't bother the flag if
         * there're no other applets here */
        if (is_rmmod) {
                if (!ONLY_APPLET)
                        option_mask32 |= OPT_r;
        } else if (!ENABLE_MODPROBE || !(option_mask32 & OPT_r)) {
# if ENABLE_FEATURE_CMDLINE_MODULE_OPTIONS
        /* If not rmmod/-r, parse possible module options given on command line.
         * insmod/modprobe takes one module name, the rest are parameters. */
                char **arg = argv;
                while (*++arg) {
                        /* Enclose options in quotes */
                        char *s = options;
                        options = xasprintf("%s \"%s\"", s ? s : "", *arg);
                        free(s);
                        *arg = NULL;
                }
# else
                argv[1] = NULL;
# endif
        }

        if (is_insmod) {
                size_t len;
                void *map;

                len = MAXINT(ssize_t);
                map = xmalloc_open_zipped_read_close(*argv, &len);
                if (!map)
                        bb_perror_msg_and_die("can't read '%s'", *argv);
                if (init_module(map, len,
                        (IF_FEATURE_CMDLINE_MODULE_OPTIONS(options ? options : ) "")
                        ) != 0
                ) {
                        bb_error_msg_and_die("can't insert '%s': %s",
                                        *argv, moderror(errno));
                }
                return EXIT_SUCCESS;
        }

        /* Try to load modprobe.dep.bb */
        if (!is_rmmod) {
                load_dep_bb();
        }

        /* Load/remove modules.
         * Only rmmod/modprobe -r loops here, insmod/modprobe has only argv[0] */
        exitcode = EXIT_SUCCESS;
        do {
                exitcode |= process_module(*argv, options);
        } while (*++argv);

        if (ENABLE_FEATURE_CLEAN_UP) {
                IF_FEATURE_CMDLINE_MODULE_OPTIONS(free(options);)
        }
        return exitcode;
#endif /* MODPROBE || INSMOD || RMMOD */
}

#endif /* MOD_APPLET_CNT > 0 */