source: MondoRescue/branches/2.2.8/2.2.8/mindi-busybox/modutils/modprobe.c@ 2817

/* vi: set sw=4 ts=4: */
/*
 * Modprobe written from scratch for BusyBox
 *
 * Copyright (c) 2002 by Robert Griebl, griebl@gmx.de
 * Copyright (c) 2003 by Andrew Dennison, andrew.dennison@motec.com.au
 * Copyright (c) 2005 by Jim Bauer, jfbauer@nfr.com
 *
 * Portions Copyright (c) 2005 by Yann E. MORIN, yann.morin.1998@anciens.enib.fr
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/

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

struct mod_opt_t {  /* one-way list of options to pass to a module */
    char *  m_opt_val;
    struct mod_opt_t * m_next;
};

struct dep_t {  /* one-way list of dependency rules */
    /* a dependency rule */
    char *  m_name;                         /* the module name*/
    char *  m_path;                         /* the module file path */
    struct mod_opt_t *  m_options;          /* the module options */

    int     m_isalias  : 1;                 /* the module is an alias */
    int     m_reserved : 15;                /* stuffin' */

    int     m_depcnt   : 16;                /* the number of dependable module(s) */
    char ** m_deparr;                       /* the list of dependable module(s) */

    struct dep_t * m_next;                  /* the next dependency rule */
};

struct mod_list_t { /* two-way list of modules to process */
    /* a module description */
    const char * m_name;
    char * m_path;
    struct mod_opt_t * m_options;

    struct mod_list_t * m_prev;
    struct mod_list_t * m_next;
};


static struct dep_t *depend;

#define main_options "acdklnqrst:vVC:"
#define INSERT_ALL     1        /* a */
#define DUMP_CONF_EXIT 2        /* c */
#define D_OPT_IGNORED  4        /* d */
#define AUTOCLEAN_FLG  8        /* k */
#define LIST_ALL       16       /* l */
#define SHOW_ONLY      32       /* n */
#define QUIET          64       /* q */
#define REMOVE_OPT     128      /* r */
#define DO_SYSLOG      256      /* s */
#define RESTRICT_DIR   512      /* t */
#define VERBOSE        1024     /* v */
#define VERSION_ONLY   2048     /* V */
#define CONFIG_FILE    4096     /* C */

#define autoclean       (main_opts & AUTOCLEAN_FLG)
#define show_only       (main_opts & SHOW_ONLY)
#define quiet           (main_opts & QUIET)
#define remove_opt      (main_opts & REMOVE_OPT)
#define do_syslog       (main_opts & DO_SYSLOG)
#define verbose         (main_opts & VERBOSE)

static int main_opts;

static int parse_tag_value(char *buffer, char **ptag, char **pvalue)
{
    char *tag, *value;

    buffer = skip_whitespace(buffer);
    tag = value = buffer;
    while (!isspace(*value))
        if (!*value) return 0;
        else value++;
    *value++ = 0;
    value = skip_whitespace(value);
    if (!*value) return 0;

    *ptag = tag;
    *pvalue = value;

    return 1;
}

/*
 * This function appends an option to a list
 */
static struct mod_opt_t *append_option(struct mod_opt_t *opt_list, char *opt)
{
    struct mod_opt_t *ol = opt_list;

    if (ol) {
        while (ol->m_next) {
            ol = ol->m_next;
        }
        ol->m_next = xmalloc(sizeof(struct mod_opt_t));
        ol = ol->m_next;
    } else {
        ol = opt_list = xmalloc(sizeof(struct mod_opt_t));
    }

    ol->m_opt_val = xstrdup(opt);
    ol->m_next = NULL;

    return opt_list;
}

#if ENABLE_FEATURE_MODPROBE_MULTIPLE_OPTIONS
/* static char* parse_command_string(char* src, char **dst);
 *   src: pointer to string containing argument
 *   dst: pointer to where to store the parsed argument
 *   return value: the pointer to the first char after the parsed argument,
 *                 NULL if there was no argument parsed (only trailing spaces).
 *   Note that memory is allocated with xstrdup when a new argument was
 *   parsed. Don't forget to free it!
 */
#define ARG_EMPTY      0x00
#define ARG_IN_DQUOTES 0x01
#define ARG_IN_SQUOTES 0x02
static char *parse_command_string(char *src, char **dst)
{
    int opt_status = ARG_EMPTY;
    char* tmp_str;

    /* Dumb you, I have nothing to do... */
    if (src == NULL) return src;

    /* Skip leading spaces */
    while (*src == ' ') {
        src++;
    }
    /* Is the end of string reached? */
    if (*src == '\0') {
        return NULL;
    }
    /* Reached the start of an argument
     * By the way, we duplicate a little too much
     * here but what is too much is freed later. */
    *dst = tmp_str = xstrdup(src);
    /* Get to the end of that argument */
    while (*tmp_str != '\0'
     && (*tmp_str != ' ' || (opt_status & (ARG_IN_DQUOTES | ARG_IN_SQUOTES)))
    ) {
        switch (*tmp_str) {
        case '\'':
            if (opt_status & ARG_IN_DQUOTES) {
                /* Already in double quotes, keep current char as is */
            } else {
                /* shift left 1 char, until end of string: get rid of the opening/closing quotes */
                memmove(tmp_str, tmp_str + 1, strlen(tmp_str));
                /* mark me: we enter or leave single quotes */
                opt_status ^= ARG_IN_SQUOTES;
                /* Back one char, as we need to re-scan the new char there. */
                tmp_str--;
            }
            break;
        case '"':
            if (opt_status & ARG_IN_SQUOTES) {
                /* Already in single quotes, keep current char as is */
            } else {
                /* shift left 1 char, until end of string: get rid of the opening/closing quotes */
                memmove(tmp_str, tmp_str + 1, strlen(tmp_str));
                /* mark me: we enter or leave double quotes */
                opt_status ^= ARG_IN_DQUOTES;
                /* Back one char, as we need to re-scan the new char there. */
                tmp_str--;
            }
            break;
        case '\\':
            if (opt_status & ARG_IN_SQUOTES) {
                /* Between single quotes: keep as is. */
            } else {
                switch (*(tmp_str+1)) {
                case 'a':
                case 'b':
                case 't':
                case 'n':
                case 'v':
                case 'f':
                case 'r':
                case '0':
                    /* We escaped a special character. For now, keep
                     * both the back-slash and the following char. */
                    tmp_str++; src++;
                    break;
                default:
                    /* We escaped a space or a single or double quote,
                     * or a back-slash, or a non-escapable char. Remove
                     * the '\' and keep the new current char as is. */
                    memmove(tmp_str, tmp_str + 1, strlen(tmp_str));
                    break;
                }
            }
            break;
        /* Any other char that is special shall appear here.
         * Example: $ starts a variable
        case '$':
            do_variable_expansion();
            break;
         * */
        default:
            /* any other char is kept as is. */
            break;
        }
        tmp_str++; /* Go to next char */
        src++; /* Go to next char to find the end of the argument. */
    }
    /* End of string, but still no ending quote */
    if (opt_status & (ARG_IN_DQUOTES | ARG_IN_SQUOTES)) {
        bb_error_msg_and_die("unterminated (single or double) quote in options list: %s", src);
    }
    *tmp_str++ = '\0';
    *dst = xrealloc(*dst, (tmp_str - *dst));
    return src;
}
#else
#define parse_command_string(src, dst)  (0)
#endif /* ENABLE_FEATURE_MODPROBE_MULTIPLE_OPTIONS */

/*
 * This function reads aliases and default module options from a configuration file
 * (/etc/modprobe.conf syntax). It supports includes (only files, no directories).
 */
static void include_conf(struct dep_t **first, struct dep_t **current, char *buffer, int buflen, int fd)
{
    int continuation_line = 0;

    // alias parsing is not 100% correct (no correct handling of continuation lines within an alias)!

    while (reads(fd, buffer, buflen)) {
        int l;
        char *p;

        p = strchr(buffer, '#');
        if (p)
            *p = 0;

        l = strlen(buffer);

        while (l && isspace(buffer[l-1])) {
            buffer[l-1] = 0;
            l--;
        }

        if (l == 0) {
            continuation_line = 0;
            continue;
        }

        if (!continuation_line) {
            if ((strncmp(buffer, "alias", 5) == 0) && isspace(buffer[5])) {
                char *alias, *mod;

                if (parse_tag_value(buffer + 6, &alias, &mod)) {
                    /* handle alias as a module dependent on the aliased module */
                    if (!*current) {
                        (*first) = (*current) = xzalloc(sizeof(struct dep_t));
                    } else {
                        (*current)->m_next = xzalloc(sizeof(struct dep_t));
                        (*current) = (*current)->m_next;
                    }
                    (*current)->m_name  = xstrdup(alias);
                    (*current)->m_isalias = 1;

                    if ((strcmp(mod, "off") == 0) || (strcmp(mod, "null") == 0)) {
                        (*current)->m_depcnt = 0;
                        (*current)->m_deparr = 0;
                    } else {
                        (*current)->m_depcnt  = 1;
                        (*current)->m_deparr  = xmalloc(1 * sizeof(char *));
                        (*current)->m_deparr[0] = xstrdup(mod);
                    }
                    (*current)->m_next    = 0;
                }
            } else if ((strncmp(buffer, "options", 7) == 0) && isspace(buffer[7])) {
                char *mod, *opt;

                /* split the line in the module/alias name, and options */
                if (parse_tag_value(buffer + 8, &mod, &opt)) {
                    struct dep_t *dt;

                    /* find the corresponding module */
                    for (dt = *first; dt; dt = dt->m_next) {
                        if (strcmp(dt->m_name, mod) == 0)
                            break;
                    }
                    if (dt) {
                        if (ENABLE_FEATURE_MODPROBE_MULTIPLE_OPTIONS) {
                            char* new_opt = NULL;
                            while ((opt = parse_command_string(opt, &new_opt))) {
                                dt->m_options = append_option(dt->m_options, new_opt);
                            }
                        } else {
                            dt->m_options = append_option(dt->m_options, opt);
                        }
                    }
                }
            } else if ((strncmp(buffer, "include", 7) == 0) && isspace(buffer[7])) {
                int fdi; char *filename;

                filename = skip_whitespace(buffer + 8);

                if ((fdi = open(filename, O_RDONLY)) >= 0) {
                    include_conf(first, current, buffer, buflen, fdi);
                    close(fdi);
                }
            }
        }
    }
}

/*
 * This function builds a list of dependency rules from /lib/modules/`uname -r`/modules.dep.
 * It then fills every modules and aliases with their default options, found by parsing
 * modprobe.conf (or modules.conf, or conf.modules).
 */
static struct dep_t *build_dep(void)
{
    int fd;
    struct utsname un;
    struct dep_t *first = 0;
    struct dep_t *current = 0;
    char buffer[2048];
    char *filename;
    int continuation_line = 0;
    int k_version;

    if (uname(&un))
        bb_error_msg_and_die("can't determine kernel version");

    k_version = 0;
    if (un.release[0] == '2') {
        k_version = un.release[2] - '0';
    }

    filename = xasprintf("/lib/modules/%s/modules.dep", un.release);
    fd = open(filename, O_RDONLY);
    if (ENABLE_FEATURE_CLEAN_UP)
        free(filename);
    if (fd < 0) {
        /* Ok, that didn't work.  Fall back to looking in /lib/modules */
        fd = open("/lib/modules/modules.dep", O_RDONLY);
        if (fd < 0) {
            return 0;
        }
    }

    while (reads(fd, buffer, sizeof(buffer))) {
        int l = strlen(buffer);
        char *p = 0;

        while (l > 0 && isspace(buffer[l-1])) {
            buffer[l-1] = 0;
            l--;
        }

        if (l == 0) {
            continuation_line = 0;
            continue;
        }

        /* Is this a new module dep description? */
        if (!continuation_line) {
            /* find the dep beginning */
            char *col = strchr(buffer, ':');
            char *dot = col;

            if (col) {
                /* This line is a dep description */
                const char *mods;
                char *modpath;
                char *mod;

                /* Find the beginning of the module file name */
                *col = 0;
                mods = bb_basename(buffer);

                /* find the path of the module */
                modpath = strchr(buffer, '/'); /* ... and this is the path */
                if (!modpath)
                    modpath = buffer; /* module with no path */
                /* find the end of the module name in the file name */
                if (ENABLE_FEATURE_2_6_MODULES &&
                     (k_version > 4) && (*(col-3) == '.') &&
                    (*(col-2) == 'k') && (*(col-1) == 'o'))
                    dot = col - 3;
                else
                    if ((*(col-2) == '.') && (*(col-1) == 'o'))
                        dot = col - 2;

                mod = xstrndup(mods, dot - mods);

                /* enqueue new module */
                if (!current) {
                    first = current = xmalloc(sizeof(struct dep_t));
                } else {
                    current->m_next = xmalloc(sizeof(struct dep_t));
                    current = current->m_next;
                }
                current->m_name    = mod;
                current->m_path    = xstrdup(modpath);
                current->m_options = NULL;
                current->m_isalias = 0;
                current->m_depcnt  = 0;
                current->m_deparr  = 0;
                current->m_next    = 0;

                p = col + 1;
            } else
                /* this line is not a dep description */
                p = 0;
        } else
            /* It's a dep description continuation */
            p = buffer;

        while (p && *p && isblank(*p))
            p++;

        /* p points to the first dependable module; if NULL, no dependable module */
        if (p && *p) {
            char *end = &buffer[l-1];
            const char *deps;
            char *dep;
            char *next;
            int ext = 0;

            while (isblank(*end) || (*end == '\\'))
                end--;

            do {
                /* search the end of the dependency */
                next = strchr(p, ' ');
                if (next) {
                    *next = 0;
                    next--;
                } else
                    next = end;

                /* find the beginning of the module file name */
                deps = bb_basename(p);
                if (deps == p) {
                    while (isblank(*deps))
                        deps++;
                }

                /* find the end of the module name in the file name */
                if (ENABLE_FEATURE_2_6_MODULES
                 && (k_version > 4) && (*(next-2) == '.')
                 && (*(next-1) == 'k') && (*next == 'o'))
                    ext = 3;
                else
                    if ((*(next-1) == '.') && (*next == 'o'))
                        ext = 2;

                /* Cope with blank lines */
                if ((next-deps-ext+1) <= 0)
                    continue;
                dep = xstrndup(deps, next - deps - ext + 1);

                /* Add the new dependable module name */
                current->m_depcnt++;
                current->m_deparr = xrealloc(current->m_deparr,
                        sizeof(char *) * current->m_depcnt);
                current->m_deparr[current->m_depcnt - 1] = dep;

                p = next + 2;
            } while (next < end);
        }

        /* is there other dependable module(s) ? */
        if (buffer[l-1] == '\\')
            continuation_line = 1;
        else
            continuation_line = 0;
    }
    close(fd);

    /*
     * First parse system-specific options and aliases
     * as they take precedence over the kernel ones.
     * >=2.6: we only care about modprobe.conf
     * <=2.4: we care about modules.conf and conf.modules
     */
    if (ENABLE_FEATURE_2_6_MODULES
     && (fd = open("/etc/modprobe.conf", O_RDONLY)) < 0)
        if (ENABLE_FEATURE_2_4_MODULES
         && (fd = open("/etc/modules.conf", O_RDONLY)) < 0)
            if (ENABLE_FEATURE_2_4_MODULES)
                fd = open("/etc/conf.modules", O_RDONLY);

    if (fd >= 0) {
        include_conf(&first, &current, buffer, sizeof(buffer), fd);
        close(fd);
    }

    /* Only 2.6 has a modules.alias file */
    if (ENABLE_FEATURE_2_6_MODULES) {
        /* Parse kernel-declared module aliases */
        filename = xasprintf("/lib/modules/%s/modules.alias", un.release);
        fd = open(filename, O_RDONLY);
        if (fd < 0) {
            /* Ok, that didn't work.  Fall back to looking in /lib/modules */
            fd = open("/lib/modules/modules.alias", O_RDONLY);
        }
        if (ENABLE_FEATURE_CLEAN_UP)
            free(filename);

        if (fd >= 0) {
            include_conf(&first, &current, buffer, sizeof(buffer), fd);
            close(fd);
        }

        /* Parse kernel-declared symbol aliases */
        filename = xasprintf("/lib/modules/%s/modules.symbols", un.release);
        fd = open(filename, O_RDONLY);
        if (fd < 0) {
            /* Ok, that didn't work.  Fall back to looking in /lib/modules */
            fd = open("/lib/modules/modules.symbols", O_RDONLY);
        }
        if (ENABLE_FEATURE_CLEAN_UP)
            free(filename);

        if (fd >= 0) {
            include_conf(&first, &current, buffer, sizeof(buffer), fd);
            close(fd);
        }
    }

    return first;
}

/* return 1 = loaded, 0 = not loaded, -1 = can't tell */
static int already_loaded(const char *name)
{
    int fd, ret = 0;
    char buffer[4096];

    fd = open("/proc/modules", O_RDONLY);
    if (fd < 0)
        return -1;

    while (reads(fd, buffer, sizeof(buffer))) {
        char *p;

        p = strchr (buffer, ' ');
        if (p) {
            const char *n;

            // Truncate buffer at first space and check for matches, with
            // the idiosyncrasy that _ and - are interchangeable because the
            // 2.6 kernel does weird things.

            *p = 0;
            for (p = buffer, n = name; ; p++, n++) {
                if (*p != *n) {
                    if ((*p == '_' || *p == '-') && (*n == '_' || *n == '-'))
                        continue;
                    break;
                }
                // If we made it to the end, that's a match.
                if (!*p) {
                    ret = 1;
                    goto done;
                }
            }
        }
    }
done:
    close (fd);
    return ret;
}

static int mod_process(const struct mod_list_t *list, int do_insert)
{
    int rc = 0;
    char **argv = NULL;
    struct mod_opt_t *opts;
    int argc_malloc; /* never used when CONFIG_FEATURE_CLEAN_UP not defined */
    int argc;

    while (list) {
        argc = 0;
        if (ENABLE_FEATURE_CLEAN_UP)
            argc_malloc = 0;
        /* If CONFIG_FEATURE_CLEAN_UP is not defined, then we leak memory
         * each time we allocate memory for argv.
         * But it is (quite) small amounts of memory that leak each
         * time a module is loaded,  and it is reclaimed when modprobe
         * exits anyway (even when standalone shell?).
         * This could become a problem when loading a module with LOTS of
         * dependencies, with LOTS of options for each dependencies, with
         * very little memory on the target... But in that case, the module
         * would not load because there is no more memory, so there's no
         * problem. */
        /* enough for minimal insmod (5 args + NULL) or rmmod (3 args + NULL) */
        argv = xmalloc(6 * sizeof(char*));
        if (do_insert) {
            if (already_loaded(list->m_name) != 1) {
                argv[argc++] = (char*)"insmod";
                if (ENABLE_FEATURE_2_4_MODULES) {
                    if (do_syslog)
                        argv[argc++] = (char*)"-s";
                    if (autoclean)
                        argv[argc++] = (char*)"-k";
                    if (quiet)
                        argv[argc++] = (char*)"-q";
                    else if (verbose) /* verbose and quiet are mutually exclusive */
                        argv[argc++] = (char*)"-v";
                }
                argv[argc++] = list->m_path;
                if (ENABLE_FEATURE_CLEAN_UP)
                    argc_malloc = argc;
                opts = list->m_options;
                while (opts) {
                    /* Add one more option */
                    argc++;
                    argv = xrealloc(argv,(argc + 1)* sizeof(char*));
                    argv[argc-1] = opts->m_opt_val;
                    opts = opts->m_next;
                }
            }
        } else {
            /* modutils uses short name for removal */
            if (already_loaded(list->m_name) != 0) {
                argv[argc++] = (char*)"rmmod";
                if (do_syslog)
                    argv[argc++] = (char*)"-s";
                argv[argc++] = (char*)list->m_name;
                if (ENABLE_FEATURE_CLEAN_UP)
                    argc_malloc = argc;
            }
        }
        argv[argc] = NULL;

        if (argc) {
            if (verbose) {
                printf("%s module %s\n", do_insert?"Loading":"Unloading", list->m_name);
            }
            if (!show_only) {
                int rc2 = wait4pid(spawn(argv));

                if (do_insert) {
                    rc = rc2; /* only last module matters */
                } else if (!rc2) {
                    rc = 0; /* success if remove any mod */
                }
            }
            if (ENABLE_FEATURE_CLEAN_UP) {
                /* the last value in the array has index == argc, but
                 * it is the terminating NULL, so we must not free it. */
                while (argc_malloc < argc) {
                    free(argv[argc_malloc++]);
                }
            }
        }
        if (ENABLE_FEATURE_CLEAN_UP) {
            free(argv);
            argv = NULL;
        }
        list = do_insert ? list->m_prev : list->m_next;
    }
    return (show_only) ? 0 : rc;
}

/*
 * Check the matching between a pattern and a module name.
 * We need this as *_* is equivalent to *-*, even in pattern matching.
 */
static int check_pattern(const char* pat_src, const char* mod_src)
{
    int ret;

    if (ENABLE_FEATURE_MODPROBE_FANCY_ALIAS) {
        char* pat;
        char* mod;
        char* p;

        pat = xstrdup(pat_src);
        mod = xstrdup(mod_src);

        for (p = pat; (p = strchr(p, '-')); *p++ = '_');
        for (p = mod; (p = strchr(p, '-')); *p++ = '_');

        ret = fnmatch(pat, mod, 0);

        if (ENABLE_FEATURE_CLEAN_UP) {
            free(pat);
            free(mod);
        }

        return ret;
    } else {
        return fnmatch(pat_src, mod_src, 0);
    }
}

/*
 * Builds the dependency list (aka stack) of a module.
 * head: the highest module in the stack (last to insmod, first to rmmod)
 * tail: the lowest module in the stack (first to insmod, last to rmmod)
 */
static void check_dep(char *mod, struct mod_list_t **head, struct mod_list_t **tail)
{
    struct mod_list_t *find;
    struct dep_t *dt;
    struct mod_opt_t *opt = 0;
    char *path = 0;

    /* Search for the given module name amongst all dependency rules.
     * The module name in a dependency rule can be a shell pattern,
     * so try to match the given module name against such a pattern.
     * Of course if the name in the dependency rule is a plain string,
     * then we consider it a pattern, and matching will still work. */
    for (dt = depend; dt; dt = dt->m_next) {
        if (check_pattern(dt->m_name, mod) == 0) {
            break;
        }
    }

    if (!dt) {
        bb_error_msg("module %s not found", mod);
        return;
    }

    // resolve alias names
    while (dt->m_isalias) {
        if (dt->m_depcnt == 1) {
            struct dep_t *adt;

            for (adt = depend; adt; adt = adt->m_next) {
                if (check_pattern(adt->m_name, dt->m_deparr[0]) == 0)
                    break;
            }
            if (adt) {
                /* This is the module we are aliased to */
                struct mod_opt_t *opts = dt->m_options;
                /* Option of the alias are appended to the options of the module */
                while (opts) {
                    adt->m_options = append_option(adt->m_options, opts->m_opt_val);
                    opts = opts->m_next;
                }
                dt = adt;
            } else {
                bb_error_msg("module %s not found", mod);
                return;
            }
        } else {
            bb_error_msg("bad alias %s", dt->m_name);
            return;
        }
    }

    mod = dt->m_name;
    path = dt->m_path;
    opt = dt->m_options;

    // search for duplicates
    for (find = *head; find; find = find->m_next) {
        if (!strcmp(mod, find->m_name)) {
            // found ->dequeue it

            if (find->m_prev)
                find->m_prev->m_next = find->m_next;
            else
                *head = find->m_next;

            if (find->m_next)
                find->m_next->m_prev = find->m_prev;
            else
                *tail = find->m_prev;

            break; // there can be only one duplicate
        }
    }

    if (!find) { // did not find a duplicate
        find = xmalloc(sizeof(struct mod_list_t));
        find->m_name = mod;
        find->m_path = path;
        find->m_options = opt;
    }

    // enqueue at tail
    if (*tail)
        (*tail)->m_next = find;
    find->m_prev = *tail;
    find->m_next = 0;

    if (!*head)
        *head = find;
    *tail = find;

    if (dt) {
        int i;

        /* Add all dependable module for that new module */
        for (i = 0; i < dt->m_depcnt; i++)
            check_dep(dt->m_deparr[i], head, tail);
    }
}

static int mod_insert(char *mod, int argc, char **argv)
{
    struct mod_list_t *tail = NULL;
    struct mod_list_t *head = NULL;
    int rc;

    // get dep list for module mod
    check_dep(mod, &head, &tail);

    rc = 1;
    if (head && tail) {
        if (argc) {
            int i;
            // append module args
            for (i = 0; i < argc; i++)
                head->m_options = append_option(head->m_options, argv[i]);
        }

        // process tail ---> head
        rc = mod_process(tail, 1);
        if (rc) {
            /*
             * In case of using udev, multiple instances of modprobe can be
             * spawned to load the same module (think of two same usb devices,
             * for example; or cold-plugging at boot time). Thus we shouldn't
             * fail if the module was loaded, and not by us.
             */
            if (already_loaded(mod))
                rc = 0;
        }
    }
    return rc;
}

static int mod_remove(char *mod)
{
    int rc;
    static const struct mod_list_t rm_a_dummy = { "-a", NULL, NULL, NULL, NULL };

    struct mod_list_t *head = NULL;
    struct mod_list_t *tail = NULL;

    if (mod)
        check_dep(mod, &head, &tail);
    else  // autoclean
        head = tail = (struct mod_list_t*) &rm_a_dummy;

    rc = 1;
    if (head && tail)
        rc = mod_process(head, 0);  // process head ---> tail
    return rc;
}

int modprobe_main(int argc, char** argv);
int modprobe_main(int argc, char** argv)
{
    int rc = EXIT_SUCCESS;
    char *unused;

    opt_complementary = "?V-:q-v:v-q";
    main_opts = getopt32(argv, "acdklnqrst:vVC:",
                            &unused, &unused);
    if (main_opts & (DUMP_CONF_EXIT | LIST_ALL))
        return EXIT_SUCCESS;
    if (main_opts & (RESTRICT_DIR | CONFIG_FILE))
        bb_error_msg_and_die("-t and -C not supported");

    depend = build_dep();

    if (!depend)
        bb_error_msg_and_die("cannot parse modules.dep");

    if (remove_opt) {
        do {
            if (mod_remove(optind < argc ?
                        argv[optind] : NULL)) {
                bb_error_msg("failed to remove module %s",
                        argv[optind]);
                rc = EXIT_FAILURE;
            }
        } while (++optind < argc);
    } else {
        if (optind >= argc)
            bb_error_msg_and_die("no module or pattern provided");

        if (mod_insert(argv[optind], argc - optind - 1, argv + optind + 1))
            bb_error_msg_and_die("failed to load module %s", argv[optind]);
    }

    /* Here would be a good place to free up memory allocated during the dependencies build. */

    return rc;
}