/* vi: set sw=4 ts=4: */
/*
 * modinfo - retrieve module info
 * Copyright (c) 2008 Pascal Bellard
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
//config:config MODINFO
//config:       bool "modinfo (24 kb)"
//config:       default y
//config:       help
//config:       Show information about a Linux Kernel module

//applet:IF_MODINFO(APPLET_NOEXEC(modinfo, modinfo, BB_DIR_SBIN, BB_SUID_DROP, modinfo))

//kbuild:lib-$(CONFIG_MODINFO) += modinfo.o modutils.o

#include <fnmatch.h>
#include <sys/utsname.h> /* uname() */
#include "libbb.h"
#include "modutils.h"

static const char *const shortcuts[] ALIGN_PTR = {
        "filename",     // -n
        "author",       // -a
        "description",  // -d
        "license",      // -l
        "parm",         // -p
        "version",      // the rest has no shortcut options
        "alias",
        "srcversion",
        "depends",
        "uts_release",
        "intree",
        "vermagic",
        "firmware",
};

enum {
        OPT_0 = (1 << 0), /* \0 as separator */
        OPT_F = (1 << 1), /* field name */
        /* first bits are for -nadlp options, the rest are for
         * fields not selectable with "shortcut" options
         */
        OPT_n = (1 << 2),
        OPT_TAGS = ((1 << ARRAY_SIZE(shortcuts)) - 1) << 2,
};

static void display(const char *data, const char *pattern)
{
        int flag = option_mask32 >> 1; /* shift out -0 bit */
        if (flag & (flag-1)) {
                /* more than one field to show: print "FIELD:" pfx */
                int n = printf("%s:", pattern);
                while (n++ < 16)
                        bb_putchar(' ');
        }
        printf("%s%c", data, (option_mask32 & OPT_0) ? '\0' : '\n');
}

static void modinfo(const char *path, const char *version,
                        const char *field)
{
        size_t len;
        int j;
        char *ptr, *the_module;
        char *allocated;
        int tags = option_mask32;

        allocated = NULL;
        len = MAXINT(ssize_t);
        the_module = xmalloc_open_zipped_read_close(path, &len);
        if (!the_module) {
                if (path[0] == '/')
                        return;
                /* Newer depmod puts relative paths in modules.dep */
                path = allocated = xasprintf("%s/%s/%s", CONFIG_DEFAULT_MODULES_DIR, version, path);
                the_module = xmalloc_open_zipped_read_close(path, &len);
                if (!the_module) {
                        bb_error_msg("module '%s' not found", path);
                        goto ret;
                }
        }

        for (j = 1; (1<<j) & (OPT_TAGS|OPT_F); j++) {
                const char *pattern;

                if (!((1<<j) & tags))
                        continue;

                pattern = field;
                if ((1<<j) & OPT_TAGS)
                        pattern = shortcuts[j-2];

                if (strcmp(pattern, shortcuts[0]) == 0) {
                        /* "-n" or "-F filename" */
                        display(path, shortcuts[0]);
                        continue;
                }

                ptr = the_module;
                while (1) {
                        char *after_pattern;

                        ptr = memchr(ptr, *pattern, len - (ptr - (char*)the_module));
                        if (ptr == NULL) /* no occurrence left, done */
                                break;
                        after_pattern = is_prefixed_with(ptr, pattern);
                        if (after_pattern && *after_pattern == '=') {
                                /* field prefixes are 0x80 or 0x00 */
                                if ((ptr[-1] & 0x7F) == 0x00) {
                                        ptr = after_pattern + 1;
                                        display(ptr, pattern);
                                        ptr += strlen(ptr);
                                }
                        }
                        ++ptr;
                }
        }
        free(the_module);
 ret:
        free(allocated);
}

//usage:#define modinfo_trivial_usage
//usage:       "[-adlpn0] [-F keyword] MODULE"
//usage:#define modinfo_full_usage "\n\n"
//usage:       "        -a              Shortcut for '-F author'"
//usage:     "\n        -d              Shortcut for '-F description'"
//usage:     "\n        -l              Shortcut for '-F license'"
//usage:     "\n        -p              Shortcut for '-F parm'"
////usage:     "\n      -n              Shortcut for '-F filename'"
//usage:     "\n        -F keyword      Keyword to look for"
//usage:     "\n        -0              NUL terminated output"
//usage:#define modinfo_example_usage
//usage:       "$ modinfo -F vermagic loop\n"

int modinfo_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int modinfo_main(int argc UNUSED_PARAM, char **argv)
{
        const char *field;
        char name[MODULE_NAME_LEN];
        struct utsname uts;
        parser_t *parser;
        char *colon, *tokens[2];
        unsigned opts;
        unsigned i;

        field = NULL;
        opts = getopt32(argv, "^" "0F:nadlp" "\0" "-1"/*minimum one arg*/, &field);
        /* If no field selected, show all */
        if (!(opts & (OPT_TAGS|OPT_F)))
                option_mask32 |= OPT_TAGS;
        argv += optind;

        uname(&uts);
        parser = config_open2(
                xasprintf("%s/%s/%s", CONFIG_DEFAULT_MODULES_DIR, uts.release, CONFIG_DEFAULT_DEPMOD_FILE),
                xfopen_for_read
        );

        while (config_read(parser, tokens, 2, 1, "# \t", PARSE_NORMAL)) {
                colon = last_char_is(tokens[0], ':');
                if (colon == NULL)
                        continue;
                *colon = '\0';
                filename2modname(bb_basename(tokens[0]), name);
                for (i = 0; argv[i]; i++) {
                        if (fnmatch(argv[i], name, 0) == 0) {
                                modinfo(tokens[0], uts.release, field);
                                argv[i] = (char *) "";
                        }
                }
        }
        if (ENABLE_FEATURE_CLEAN_UP)
                config_close(parser);

        for (i = 0; argv[i]; i++) {
                if (argv[i][0]) {
                        modinfo(argv[i], uts.release, field);
                }
        }

        return 0;
}