/*
 * Common modutils related functions for busybox
 *
 * Copyright (C) 2008 by Timo Teras <timo.teras@iki.fi>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
#include "modutils.h"

#include <sys/syscall.h>

#define init_module(mod, len, opts) syscall(__NR_init_module, mod, len, opts)
#if defined(__NR_finit_module)
# define finit_module(fd, uargs, flags) syscall(__NR_finit_module, fd, uargs, flags)
#endif
#define delete_module(mod, flags) syscall(__NR_delete_module, mod, flags)

static module_entry *helper_get_module(module_db *db, const char *module, int create)
{
        char modname[MODULE_NAME_LEN];
        struct module_entry *e;
        unsigned i, hash;

        filename2modname(module, modname);

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

        for (e = db->buckets[hash]; e; e = e->next)
                if (strcmp(e->modname, modname) == 0)
                        return e;
        if (!create)
                return NULL;

        e = xzalloc(sizeof(*e));
        e->modname = xstrdup(modname);
        e->next = db->buckets[hash];
        db->buckets[hash] = e;
        IF_DEPMOD(e->dnext = e->dprev = e;)

        return e;
}
module_entry* FAST_FUNC moddb_get(module_db *db, const char *module)
{
        return helper_get_module(db, module, 0);
}
module_entry* FAST_FUNC moddb_get_or_create(module_db *db, const char *module)
{
        return helper_get_module(db, module, 1);
}

void FAST_FUNC moddb_free(module_db *db)
{
        module_entry *e, *n;
        unsigned i;

        for (i = 0; i < MODULE_HASH_SIZE; i++) {
                for (e = db->buckets[i]; e; e = n) {
                        n = e->next;
                        free(e->name);
                        free(e->modname);
                        free(e);
                }
        }
}

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

int FAST_FUNC string_to_llist(char *string, llist_t **llist, const char *delim)
{
        char *tok;
        int len = 0;

        while ((tok = strsep(&string, delim)) != NULL) {
                if (tok[0] == '\0')
                        continue;
                llist_add_to_end(llist, xstrdup(tok));
                len += strlen(tok);
        }
        return len;
}

char* FAST_FUNC filename2modname(const char *filename, char *modname)
{
        char local_modname[MODULE_NAME_LEN];
        int i;
        const char *from;

        if (filename == NULL)
                return NULL;
        if (modname == NULL)
                modname = local_modname;
        // 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';

        if (modname == local_modname)
                return xstrdup(modname);

        return modname;
}

#if ENABLE_FEATURE_CMDLINE_MODULE_OPTIONS
char* FAST_FUNC parse_cmdline_module_options(char **argv, int quote_spaces)
{
        char *options;
        int optlen;

        options = xzalloc(1);
        optlen = 0;
        while (*++argv) {
                const char *fmt;
                const char *var;
                const char *val;

                var = *argv;
                options = xrealloc(options, optlen + 2 + strlen(var) + 2);
                fmt = "%.*s%s ";
                val = strchrnul(var, '=');
                if (quote_spaces) {
                        /*
                         * modprobe (module-init-tools version 3.11.1) compat:
                         * quote only value:
                         * var="val with spaces", not "var=val with spaces"
                         * (note: var *name* is not checked for spaces!)
                         */
                        if (*val) { /* has var=val format. skip '=' */
                                val++;
                                if (strchr(val, ' '))
                                        fmt = "%.*s\"%s\" ";
                        }
                }
                optlen += sprintf(options + optlen, fmt, (int)(val - var), var, val);
        }
        /* Remove trailing space. Disabled */
        /* if (optlen != 0) options[optlen-1] = '\0'; */
        return options;
}
#endif

#if ENABLE_FEATURE_INSMOD_TRY_MMAP
void* FAST_FUNC try_to_mmap_module(const char *filename, size_t *image_size_p)
{
        /* We have user reports of failure to load 3MB module
         * on a 16MB RAM machine. Apparently even a transient
         * memory spike to 6MB during module load
         * is too big for that system. */
        void *image;
        struct stat st;
        int fd;

        fd = xopen(filename, O_RDONLY);
        fstat(fd, &st);
        image = NULL;
        /* st.st_size is off_t, we can't just pass it to mmap */
        if (st.st_size <= *image_size_p) {
                size_t image_size = st.st_size;
                image = mmap(NULL, image_size, PROT_READ, MAP_PRIVATE, fd, 0);
                if (image == MAP_FAILED) {
                        image = NULL;
                } else if (*(uint32_t*)image != SWAP_BE32(0x7f454C46)) {
                        /* No ELF signature. Compressed module? */
                        munmap(image, image_size);
                        image = NULL;
                } else {
                        /* Success. Report the size */
                        *image_size_p = image_size;
                }
        }
        close(fd);
        return image;
}
#endif

/* Return:
 * 0 on success,
 * -errno on open/read error,
 * errno on init_module() error
 */
int FAST_FUNC bb_init_module(const char *filename, const char *options)
{
        size_t image_size;
        char *image;
        int rc;
        bool mmaped;

        if (!options)
                options = "";

//TODO: audit bb_init_module_24 to match error code convention
#if ENABLE_FEATURE_2_4_MODULES
        if (get_linux_version_code() < KERNEL_VERSION(2,6,0))
                return bb_init_module_24(filename, options);
#endif

        /*
         * 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.
         */
# ifdef __NR_finit_module
        {
                int fd = open(filename, O_RDONLY | O_CLOEXEC);
                if (fd >= 0) {
                        rc = finit_module(fd, options, 0) != 0;
                        close(fd);
                        if (rc == 0)
                                return rc;
                }
        }
# endif

        image_size = INT_MAX - 4095;
        mmaped = 0;
        image = try_to_mmap_module(filename, &image_size);
        if (image) {
                mmaped = 1;
        } else {
                errno = ENOMEM; /* may be changed by e.g. open errors below */
                image = xmalloc_open_zipped_read_close(filename, &image_size);
                if (!image)
                        return -errno;
        }

        errno = 0;
        init_module(image, image_size, options);
        rc = errno;
        if (mmaped)
                munmap(image, image_size);
        else
                free(image);
        return rc;
}

int FAST_FUNC bb_delete_module(const char *module, unsigned int flags)
{
        errno = 0;
        delete_module(module, flags);
        return errno;
}

/* Note: not suitable for delete_module() errnos.
 * For them, probably only EWOULDBLOCK needs explaining:
 * "Other modules depend on us". So far we don't do such
 * translation and don't use moderror() for removal errors.
 */
const char* FAST_FUNC moderror(int err)
{
        switch (err) {
        case -1: /* btw: it's -EPERM */
                return "no such module";
        case ENOEXEC:
                return "invalid module format";
        case ENOENT:
                return "unknown symbol in module, or unknown parameter";
        case ESRCH:
                return "module has wrong symbol version";
        case ENOSYS:
                return "kernel does not support requested operation";
        }
        if (err < 0) /* should always be */
                err = -err;
        return strerror(err);
}