/*
 * file-lock.c
 *
 * Copyright (C) 2008 Oracle Inc.
 * Copyright (C) 2008 Zhigang Wang <zhigang.x.wang@oracle.com>
 *
 * 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, either version 3 of the License, or (at your option)
 * any later version.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <getopt.h>

const char version[] = "0.0.1";
static char short_opts[] = "lup:d:n:hvV";
static struct option long_opts[] = {
	{ "lock",	no_argument,		NULL,	'l' },
	{ "unlock",	no_argument,		NULL,	'u' },
	{ "path",	required_argument,	NULL,	'p' },
	{ "name",	required_argument,	NULL,	'n' },
	{ "uuid",	required_argument,	NULL,	'd' },
	{ "help",	no_argument,		NULL,	'h' },
	{ "verbose",	no_argument,		NULL,	'v' },
	{ "version",	no_argument,		NULL,	'V' },
	{  NULL,	0,			NULL,	 0  }
};

static void usage(char *prog, FILE *fp, int n) {
	fprintf(fp, "usage: %s [options]\n", prog);
	fprintf(fp, "\n");
	fprintf(fp, "options:\n");
	fprintf(fp, " -l, --lock       Acquire the lock.\n");
	fprintf(fp, " -u, --unlock     Release the lock.\n");
	fprintf(fp, " -p, --path       Set the path for the locks.\n");
	fprintf(fp, " -n, --name       Set the name of the VM.\n");
	fprintf(fp, " -d, --uuid       Set the uuid of the VM.\n");
	fprintf(fp, " -v, --verbose    Show more infomation.\n");
	fprintf(fp, " -V, --version    Show version number and exit.\n");
	fprintf(fp, " -h, --help       Show this help information.\n");
	fprintf(fp, "\n");
	exit(n);
}

static int do_lock(char *path, char *name, char *uuid)
{
	char *fn;
	int fd;

	if (asprintf(&fn, "%s/%s-%s.lock", path, name, uuid) == -1)
		return -1;

	fd = open(fn, O_CREAT|O_RDWR|O_EXCL, S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
	if (fd == -1) {
		free(fn);
		return errno;
	}

	free(fn);
	close(fd);
	return 0;
}

static int do_unlock(char *path, char *name, char *uuid)
{
	char *fn;

	if (asprintf(&fn, "%s/%s-%s.lock", path, name, uuid) == -1)
		return -1;

	if (unlink(fn) == -1) {
		free(fn);
		return errno;
	}

	free(fn);
	return 0;
}

int main(int argc, char *argv[])
{
	char *prog, *p;
	char *name = NULL;
	char *uuid = NULL;
	char *path = ".";	/* create lock file on current working directory by default*/
	int verbose = 0;	/* turn off verbose output by default */
	int status = 0;		/* returned value */
	int lock = 0, unlock = 0;
	int c;

	prog = argv[0];
	p = strrchr(prog, '/');
	if (p)
		prog = p+1;

	while ((c = getopt_long(argc, argv, short_opts,
				 long_opts, NULL)) != -1) {
		switch (c) {
		case 'l':		/* acquire the lock */
			lock = 1;
			break;
		case 'u':		/* release the lock */
			unlock = 1;
			break;
		case 'p':		/* path for lock file */
			path = optarg;
			break;
		case 'n':		/* name of vm  */
			name = optarg;
			break;
		case 'd':		/* uuid of vm  */
			uuid = optarg;
			break;
		case 'h':		/* help */
			usage(prog, stdout, 0);
			break;
		case 'v':		/* be chatty */
			++verbose;
			break;
		case 'V':		/* version */
			fprintf(stdout, "%s: %s\n", prog, version);
			exit(0);
		case 0:
			break;
		case '?':
		default:
			usage(prog, stderr, 1);
		}
	}

	if (optind < argc)
		usage(prog, stderr, 1);

	if (name==NULL || uuid==NULL) {
		fprintf(stderr, "you should specify the name and uuid of vm.\n\n");
		usage(prog, stderr, 1);
	}

	if (lock && unlock) {
		fprintf(stderr, "cannot execute lock and unlock at the same time.\n\n");
		usage(prog, stderr, 1);
	}

	if (lock) {
		if (verbose)
			fprintf(stdout, "creating lock file %s/%s-%s.lock\n", path, name, uuid);

		status = do_lock(path, name, uuid);

		if (verbose)
			if (status == 0)
				fprintf(stdout, "lock sucess.\n");
			else
				fprintf(stdout, "lock failed.\n");
	} else if (unlock) {
		if (verbose)
			fprintf(stdout, "removing lock file %s/%s-%s.lock\n", path, name, uuid);

		status = do_unlock(path, name, uuid);

		if (verbose)
			if (status == 0)
				fprintf(stdout, "unlock sucess.\n");
			else
				fprintf(stdout, "unlock failed.\n");
	} else {
		fprintf(stderr, "you should specify lock or unlock.\n\n");
		usage(prog, stderr, 1);
	}

	return status;
}