options.c

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include "options.h"

//Global variables
const int ON = 1;
const int OFF = 0;
const int ERROR = -1;
const int maxPid = 32768;

//Initializes all of the options then sets them according to command line input
int initOptions(int argc, char *argv[], struct options *flags)
{
	flags->p = OFF;
	flags->s = OFF;
	flags->U = OFF;
	flags->S = OFF;
	flags->v = OFF;
	flags->c = OFF;
	return argsCheck(argc, argv, flags);
}

//argsCheck uses getopt to check the command line arguments and stores them
//into the passed structure. Returns -1 on error.
int argsCheck(int argc, char *argv[], struct options *flags)
{
	int opt;
	
	//opterr disables error outputs
	opterr = 0;
	while ((opt = getopt(argc, argv, "p:s::U::S::v::c::")) != -1)
	{
		switch (opt)
		{
			case 's':
				flags->s = ON;
				if (optarg != 0 && argv[optind - 1][2] == '-')
					flags->s = OFF;
				else if (optarg != 0)
					return ERROR;
				break;
				//p case is only exception. checks for valid PID argument.
			case 'p':
				if (optarg == NULL) {}
				else
				{
					flags->p = atoi(optarg);
					if (flags->p <= 0 || flags->p > maxPid)
						return ERROR;
				}
				break;
			case 'U':
				flags->U = ON;
				if (optarg != 0 && argv[optind - 1][2] == '-')
					flags->U = OFF;
				else if (optarg != 0)
					return ERROR;
				break;
			case 'S':
				flags->S = ON;
				if (optarg != 0 && argv[optind - 1][2] == '-')
					flags->S = OFF;
				else if (optarg != 0)
					return ERROR;
				break;
			case 'v':
				flags->v = ON;
				if (optarg != 0 && argv[optind - 1][2] == '-')
					flags->v = OFF;
				else if (optarg != 0)
					return ERROR;
				break;
			case 'c':
				flags->c = ON;
				if (optarg != 0 && argv[optind - 1][2] == '-')
					flags->c = OFF;
				else if (optarg != 0)
					return ERROR;
				break;
				//'?' case is a catch-all for unnacceptable arguments
			case '?':
				return ERROR;
		}
	}
	//returns 0 if everything passed 
	return 0;
}