/*
 *  sloth v1.1.0
 *  Copyright (C) 2002  Nick Jennings <nick@namodn.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; 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 *  This program is developed and maintained by Nick Jennings.
 * Contact Information:
 *
 * $Id: sloth.c,v 1.9 2002/02/10 08:58:20 nick Exp $
 *
 */

#include <stdio.h>
#include <sys/wait.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/time.h>

// Constants
#define VERSION "1.1.0"
#define DEFAULT_SPEED 0
#define POS_SPEED 1
#define POS_PROG 2
#define TOTAL_ARGS 3

// Prototypes
void usage();

/*****************************************************************************
 * int main(int argc, char *argv[]);
 *
 * sloth <0-99999> <progname>
 *
 */
int main(int argc, char *argv[]) {
	pid_t pid;
	int exit_code = 0;
	int i = 0;
	int spawn = 0;
	int status = 0;
	long dspeed = DEFAULT_SPEED;  // delay speed
	long wspeed = DEFAULT_SPEED; // wait speed
	struct timeval timeout;

	if (argc < TOTAL_ARGS) {
		usage();
		exit_code = 1;
	} else if ((long)atoi(argv[POS_SPEED]) < 0) {
		usage();
		exit_code = 1;
	} else {
		// get wait between delays
		wspeed = (long)atoi(argv[POS_SPEED]); 
	}

	// calc delay
	dspeed = wspeed * 10;

	// determin process management behavior
	while (*(argv[POS_PROG]+i) != '\0' && (!spawn)) {
		if ( *(argv[POS_PROG]+i) >= 48 &&
		     *(argv[POS_PROG]+i) <= 57 ) {
			// character is a number
			spawn = 0;
		} else {
			spawn = 1;
		}
		i++;
	}
	
	if (!exit_code) {
		if (spawn) {
			// control spawned process
			pid = fork();
			if (pid != 0) {
				while(!waitpid(pid, &status, WNOHANG)) {
					// wait
					timeout.tv_sec = 0;
					timeout.tv_usec = wspeed;
					select(0, (fd_set *)0, (fd_set *)0, (fd_set *)0, &timeout);
					// stop
					kill(pid, SIGSTOP);
					// delay
					timeout.tv_sec = 0;
					timeout.tv_usec = dspeed;
					select(0, (fd_set *)0, (fd_set *)0, (fd_set *)0, &timeout);
					// continue
					kill(pid, SIGCONT);
				}
			}
			else {
				// child execution begins 
				execvp(argv[POS_PROG], &argv[POS_PROG]);
				return(0);
			}
		} else {
			// control existing process
			pid = (pid_t)atoi(argv[POS_PROG]);
			while(!exit_code) {
				// wait
				timeout.tv_sec = 0;
				timeout.tv_usec = wspeed;
				select(0, (fd_set *)0, (fd_set *)0, (fd_set *)0, &timeout);
				// stop
				if (0 > kill(pid, SIGSTOP)) {
					printf("sloth: failed sending signal to PID '%d'. No permission or PID does not exist.\n", pid);
					exit_code = 2;
				} else {
					// delay
					timeout.tv_sec = 0;
					timeout.tv_usec = dspeed;
					select(0, (fd_set *)0, (fd_set *)0, (fd_set *)0, &timeout);
					// continue
					if (0 > kill(pid, SIGCONT)) {
						printf("sloth: failed sending signal to PID '%d'. No permission or PID does not exist.\n", pid);
						exit_code = 2;
					}
				}
			}
		}
	}
	exit(exit_code);
}


/*****************************************************************************
 * void usage();
 *
 * displays usage text
 *
 */
void usage() {
	printf("sloth version %s\n", VERSION);
	printf("usage: sloth <0-99999> <progname>\n");
}