/* vi: set sw=4 ts=4: */
/*
 * depmod - generate modules.dep
 * Copyright (c) 2008 Bernhard Fischer
 *
 * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
 */

#undef _GNU_SOURCE
#define _GNU_SOURCE
#include <libbb.h>
#include <sys/utsname.h> /* uname() */

/*
 * Theory of operation:
 * - iterate over all modules and record their full path
 * - iterate over all modules looking for "depends=" entries
 *   for each depends, look through our list of full paths and emit if found
 */
struct globals {
	llist_t *lst;
};
#define G (*(struct globals*)&bb_common_bufsiz1)
/* We have to zero it out because of NOEXEC */
#define INIT_G() memset(&G, 0, sizeof(G))

static int fill_lst(const char *modulename, struct stat ATTRIBUTE_UNUSED *sb,
					void ATTRIBUTE_UNUSED *data, int ATTRIBUTE_UNUSED depth)
{
	llist_add_to(&G.lst, strdup(modulename));
	return TRUE;
}

static int fileAction(const char *fname, struct stat *sb,
					void *data, int ATTRIBUTE_UNUSED depth)
{
	size_t len = sb->st_size;
	void *the_module, *ptr;
	int fd;
	char *depends, *deps;

/*XXX: FIXME: does not handle compressed modules!
 * There should be a function that looks at the extension and sets up
 * open_transformer for us.
 */
	if (last_char_is(fname, 'o') == NULL) /* not a module */
		goto skip;

	fd = xopen(fname, O_RDONLY);
	the_module = mmap(NULL, len, PROT_READ, MAP_SHARED
#if defined MAP_POPULATE
						|MAP_POPULATE
#endif
						, fd, 0);
	close(fd);
	if (the_module == MAP_FAILED)
		bb_perror_msg_and_die("mmap");

	ptr = the_module;

	fprintf((FILE*)data, "\n%s:", fname);
//bb_info_msg("fname='%s'", fname);
	do {
		/* search for a 'd' */
		ptr = memchr(ptr, 'd', len);
		if (ptr == NULL) /* no d left, done */
			goto done;
		if (memcmp(ptr, "depends=", sizeof("depends=")-1) == 0)
			break;
		len -= ++ptr - the_module;
	} while (1);
	deps = depends = strdup (ptr + sizeof("depends=")-1);
//bb_info_msg(" depends='%s'", depends);
	while (*deps) {
		llist_t * _lst = G.lst;
		char *buf1;

		ptr = strchr(deps, ',');
		if (ptr != NULL)
			*(char*)ptr = '\0';
		/* remember the length of the current dependency plus eventual 0 byte */
		len = strlen(deps) + (ptr != NULL);
		buf1 = xmalloc(len + 3);
		sprintf(buf1, "/%s.", deps); /* make sure we match the correct file */
		while (_lst) {
			ptr = strstr(_lst->data, buf1);
			if (ptr != NULL)
				break; /* found it */
			_lst = _lst->link;
		}
		free(buf1);
		if (_lst /*&& _lst->data*/) {
//bb_info_msg("[%s] -> '%s'", deps, _lst->data);
			fprintf((FILE*)data, " %s", _lst->data);
			deps += len;
		}
	}
	free(depends);
done:
	munmap(the_module, sb->st_size);
skip:
	return TRUE;
}

int depmod_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int depmod_main(int ATTRIBUTE_UNUSED argc, char **argv)
{
	int retval = EXIT_SUCCESS;
//	static const char moddir_base[] ALIGN1 = "/lib/modules/%s";
	FILE *filedes = xfopen("/tmp/modules.dep", "w");

	argv++;
	do {
		if (!recursive_action(*argv,
				ACTION_RECURSE, /* flags */
				fill_lst, /* file action */
				NULL, /* dir action */
				NULL, /* user data */
				0) || /* depth */
			!recursive_action(*argv,
				ACTION_RECURSE, /* flags */
				fileAction, /* file action */
				NULL, /* dir action */
				(void*)filedes, /* user data */
				0)) { /* depth */
			retval = EXIT_FAILURE;
		}
	} while (*++argv);

	if (ENABLE_FEATURE_CLEAN_UP) {
		fclose(filedes);
		llist_free(G.lst, free);
	}
	return retval;
}