/* " Copyright (C) 2009 Red Hat, Inc. All Rights Reserved.
 * " Written by Ivana Hutarova Varekova <varekova@redhat.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 */

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>

#include <libcgroup.h>

enum flag{
    FL_MOUNT = 1,
    FL_LIST = 2
};

typedef char cont_name_t[FILENAME_MAX];

void usage(int status, char *program_name)
{
	if (status != 0) {
		fprintf(stderr, "Wrong input parameters,"
			" try %s -h' for more information.\n",
			program_name);
	} else {
		fprintf(stdout, "Usage: %s [-m] [controller] [...]\n",
			program_name);
		fprintf(stdout, "list all sybsystems of given controller\n");
		fprintf(stdout, "  -h, --help		Display this help\n");
		fprintf(stdout, "  -m, --mount-points	Display mount points\n");
	}
}

/* print data about input cont_name controller */
int print_controller(cont_name_t cont_name, int flags)
{
	int ret = 0;
	char name[FILENAME_MAX];
	char path[FILENAME_MAX];
	void *handle;
	struct cgroup_mount_point controller;
	int output = 0;

	ret = cgroup_get_controller_begin(&handle, &controller);

	path[0] = '\0';
	name[0] = '\0';

	/* go through the list of controllers */
	while (ret == 0) {
		if (strcmp(path, controller.path) == 0) {
			/* if it is still the same mount point */
			strncat(name, "," , FILENAME_MAX-strlen(name)-1);
			strncat(name, controller.name,
				FILENAME_MAX-strlen(name)-1);
		} else {
			/*
			 * we got new mount point
			 * print the old one if needed
			 */
			if (output) {
				if ((flags &  FL_MOUNT) != 0)
					printf("%s %s\n", name, path);
				else
					printf("%s \n", name);
				if ((flags & FL_LIST) != 0) {
					/* we succesfully finish printing */
					output = 0;
					break;
				}
			}

			output = 0;
			strncpy(name, controller.name, FILENAME_MAX);
			name[FILENAME_MAX-1] = '\0';
			strncpy(path, controller.path, FILENAME_MAX);
			path[FILENAME_MAX-1] = '\0';
		}

		/* set output flag */
		if ((!output) && (!(flags & FL_LIST) ||
			(strcmp(controller.name, cont_name) == 0)))
			output = 1;

		/* the actual controller should not be printed */
		ret = cgroup_get_controller_next(&handle, &controller);
	}

	if (output) {
		if ((flags &  FL_MOUNT) != 0)
			printf("%s %s\n", name, path);
		else
			printf("%s \n", name);
		if ((flags & FL_LIST) != 0)
			ret = 0;
	}

	cgroup_get_controller_end(&handle);
	return ret;

}

/* list the controllers */
int cgroup_list_controllers(char *tname,
	cont_name_t cont_name[CG_CONTROLLER_MAX], int flags)
{
	int ret = 0;
	int final_ret = 0;
	int i = 0;

	/* initialize libcgroup */
	ret = cgroup_init();
	if (ret) {
		fprintf(stderr, "controllers can't be listed: %s\n",
			cgroup_strerror(ret));
		return ret;
	}

	if ((flags & FL_LIST) == 0) {
		/* we have to print all controllers */
		ret = print_controller(NULL, flags);
		if (ret == ECGEOF)
			final_ret = 0;
		else
			fprintf(stderr, "controllers can't be listed: %s\n",
				cgroup_strerror(ret));
	} else
		/* we have he list of controllers which should be print */
		while ((i < CG_CONTROLLER_MAX) && (cont_name[i][0] != '\0')
			&& ((ret == ECGEOF) || (ret == 0))) {
			ret = print_controller(cont_name[i], flags);
			if (ret != 0) {
				if (ret == ECGEOF)
					/* controller was not found */
					final_ret = ECGFAIL;
				else
					/* other problem */
					final_ret = ret;
				fprintf(stderr,
					"%s: cannot find group %s: %s\n",
					tname, cont_name[i],
					cgroup_strerror(final_ret));
			}
			i++;
		}

	return final_ret;
}

int main(int argc, char *argv[])
{

	int ret = 0;
	int c;

	int flags = 0;

	int i;
	int c_number = 0;
	cont_name_t cont_name[CG_CONTROLLER_MAX];

	static struct option options[] = {
		{"help", 0, 0, 'h'},
		{"mount-points", 0, 0, 'm'},
		{0, 0, 0, 0}
	};

	for (i = 0; i < CG_CONTROLLER_MAX; i++)
		cont_name[i][0] = '\0';

	/* parse arguments */
	while ((c = getopt_long(argc, argv, "mh", options, NULL)) > 0) {
		switch (c) {
		case 'h':
			usage(0, argv[0]);
			return 0;
		case 'm':
			flags |= FL_MOUNT;
			break;
		default:
			usage(1, argv[0]);
			return -1;
		}
	}

	/* read the list of controllers */
	while (optind < argc) {

		flags |= FL_LIST;
		strncpy(cont_name[c_number], argv[optind], FILENAME_MAX);
		cont_name[c_number][FILENAME_MAX-1] = '\0';
		c_number++;
		optind++;
		if (optind == CG_CONTROLLER_MAX) {
			fprintf(stderr, "too much parameters\n");
			break;
		}
	}

	/*
	 * print the information
	 * based on list of input controllers and flags
	 */
	ret = cgroup_list_controllers(argv[0], cont_name, flags);

	return ret;
}