/*
 * Copyright (C) 2004-2006 Kay Sievers <kay@vrfy.org>
 * Copyright (C) 2006 Hannes Reinecke <hare@suse.de>
 *
 *	This program is free software; you can redistribute it and/or modify it
 *	under the terms of the GNU General Public License as published by the
 *	Free Software Foundation version 2 of the License.
 *
 *	This program is distributed in the hope that it will be useful, but
 *	WITHOUT ANY WARRANTY; without even the implied warranty of
 *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *	General Public License for more details.
 *
 *	You should have received a copy of the GNU General Public License along
 *	with this program; if not, write to the Free Software Foundation, Inc.,
 *	51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 */

#include <stdlib.h>
#include <stddef.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdbool.h>
#include <unistd.h>
#include <getopt.h>
#include <errno.h>
#include <dirent.h>
#include <fcntl.h>
#include <syslog.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <string.h>

#define PATH_SIZE 512

#ifndef strlcpy
#define strlcpy(d,s,l) (strncpy(d,s,l), (d)[(l)-1] = '\0')
#endif

#ifndef strlcat
#define strlcat(d,s,l) strncat(d,s,(l)-strlen(d)-1)
#endif

static int verbose;
static int dry_run;

static void log_message(int priority, const char *format, ...)
{
	va_list args;

	va_start(args, format);
	vsyslog(priority, format, args);
	va_end(args);
}

#undef err
#define err(format, arg...)                         \
    do {                                    \
        log_message(LOG_ERR ,"%s: " format ,__FUNCTION__ ,## arg);  \
    } while (0)

#undef info
#define info(format, arg...)                            \
    do {                                    \
        log_message(LOG_INFO ,"%s: " format ,__FUNCTION__ ,## arg); \
    } while (0)

#ifdef DEBUG
#undef dbg
#define dbg(format, arg...)                         \
    do {                                    \
        log_message(LOG_DEBUG ,"%s: " format ,__FUNCTION__ ,## arg);    \
    } while (0)
#else
#define dbg(...) do {} while(0)
#endif


static void trigger_uevent(const char *devpath)
{
	char filename[PATH_SIZE];
	int fd;

	strlcpy(filename, "/sys", sizeof(filename));
	strlcat(filename, devpath, sizeof(filename));
	strlcat(filename, "/uevent", sizeof(filename));

	if (verbose)
		printf("%s\n", devpath);

	if (dry_run)
		return;

	fd = open(filename, O_WRONLY);
	if (fd < 0) {
		dbg("error on opening %s: %s\n", filename, strerror(errno));
		return;
	}

	if (write(fd, "add", 3) < 0)
		info("error on triggering %s: %s\n", filename, strerror(errno));

	close(fd);
}

static int sysfs_resolve_link(char *devpath, size_t size)
{
	char link_path[PATH_SIZE];
	char link_target[PATH_SIZE];
	int len;
	int i;
	int back;

	strlcpy(link_path, "/sys", sizeof(link_path));
	strlcat(link_path, devpath, sizeof(link_path));
	len = readlink(link_path, link_target, sizeof(link_target));
	if (len <= 0)
		return -1;
	link_target[len] = '\0';
	dbg("path link '%s' points to '%s'", devpath, link_target);

	for (back = 0; strncmp(&link_target[back * 3], "../", 3) == 0; back++)
		;
	dbg("base '%s', tail '%s', back %i", devpath, &link_target[back * 3], back);
	for (i = 0; i <= back; i++) {
		char *pos = strrchr(devpath, '/');

		if (pos == NULL)
			return -1;
		pos[0] = '\0';
	}
	dbg("after moving back '%s'", devpath);
	strlcat(devpath, "/", size);
	strlcat(devpath, &link_target[back * 3], size);
	return 0;
}

static bool device_has_attribute(const char *path, const char *attr,
				 mode_t mode)
{
	char filename[PATH_SIZE];
	struct stat statbuf;

	strlcpy(filename, path, sizeof(filename));
	strlcat(filename, attr, sizeof(filename));

	if (stat(filename, &statbuf) < 0)
		return false;

	if (!(statbuf.st_mode & mode))
		return false;

	return true;
}

static int device_list_insert(const char *path)
{
	char devpath[PATH_SIZE];
	struct stat statbuf;

	dbg("add '%s'" , path);

	/* we only have a device, if we have a dev and an uevent file */
	if (!device_has_attribute(path, "/dev", S_IRUSR) ||
	    !device_has_attribute(path, "/uevent", S_IWUSR))
		return -1;

	strlcpy(devpath, &path[4], sizeof(devpath));

	/* resolve possible link to real target */
	if (lstat(path, &statbuf) < 0)
		return -1;
	if (S_ISLNK(statbuf.st_mode))
		if (sysfs_resolve_link(devpath, sizeof(devpath)) != 0)
			return -1;

	trigger_uevent(devpath);
	return 0;
}

static void scan_subdir(const char *base, const char *subdir,
		        bool insert, int depth)
{
	DIR *dir;
	struct dirent *dent;

	dir = opendir(base);
	if (dir == NULL)
		return;

	for (dent = readdir(dir); dent != NULL; dent = readdir(dir)) {
		char dirname[PATH_SIZE];

		if (dent->d_name[0] == '.')
			continue;

		strlcpy(dirname, base, sizeof(dirname));
		strlcat(dirname, "/", sizeof(dirname));
		strlcat(dirname, dent->d_name, sizeof(dirname));

		if (insert) {
			int err;

			err = device_list_insert(dirname);
			if (err)
				continue;
		}

		if (subdir)
			strlcat(dirname, subdir, sizeof(base));

		if (depth)
			scan_subdir(dirname, NULL, true, depth - 1);
	}

	closedir(dir);
}

int main(int argc, char *argv[], char *envp[])
{
	struct stat statbuf;
	int option;

	openlog("udevtrigger", LOG_PID | LOG_CONS, LOG_DAEMON);

	while (1) {
		option = getopt(argc, argv, "vnh");
		if (option == -1)
			break;

		switch (option) {
		case 'v':
			verbose = 1;
			break;
		case 'n':
			dry_run = 1;
			break;
		case 'h':
			printf("Usage: udevtrigger OPTIONS\n"
			       "  -v                     print the list of devices while running\n"
			       "  -n                     do not actually trigger the events\n"
			       "  -h                     print this text\n"
			       "\n");
			goto exit;
		default:
			goto exit;
		}
	}


	/* if we have /sys/subsystem, forget all the old stuff */
	scan_subdir("/sys/bus", "/devices", false, 1);
	scan_subdir("/sys/class", NULL, false, 1);

	/* scan "block" if it isn't a "class" */
	if (stat("/sys/class/block", &statbuf) != 0)
		scan_subdir("/sys/block", NULL, true, 1);

exit:

	closelog();
	return 0;
}