getopt.h

//Copyright 2017 Dr. Frazer K. Noble
//
//Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files(the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions :
//
//The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
//
//THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#ifndef GETOPT_H_
#define GETOPT_H_

#include <string.h>
#include <stdio.h>

int     opterr = 1,             /* if error message should be printed */
optind = 1,             /* index into parent argv vector */
optopt,                 /* character checked for validity */
optreset;               /* reset getopt */
char    *optarg;                /* argument associated with option */

#define BADCH   (int)'?'
#define BADARG  (int)':'
#define EMSG    ""

								/*
								* getopt --
								*      Parse argc/argv argument vector.
								*/
int
GetOpt(int nargc, char * const nargv[], const char *ostr)
{
	static char *place = EMSG;              /* option letter processing */
	const char *oli;                        /* option letter list index */

	if (optreset || !*place) {              /* update scanning pointer */
		optreset = 0;
		if (optind >= nargc || *(place = nargv[optind]) != '-') {
			place = EMSG;
			return (-1);
		}
		if (place[1] && *++place == '-') {      /* found "--" */
			++optind;
			place = EMSG;
			return (-1);
		}
	}                                       /* option letter okay? */
	if ((optopt = (int)*place++) == (int)':' ||
		!(oli = strchr(ostr, optopt))) {
		/*
		* if the user didn't specify '-' as an option,
		* assume it means -1.
		*/
		if (optopt == (int)'-')
			return (-1);
		if (!*place)
			++optind;
		if (opterr && *ostr != ':')
			(void)printf("illegal option -- %c\n", optopt);
		return (BADCH);
	}
	if (*++oli != ':') {                    /* don't need argument */
		optarg = NULL;
		if (!*place)
			++optind;
	}
	else {                                  /* need an argument */
		if (*place)                     /* no white space */
			optarg = place;
		else if (nargc <= ++optind) {   /* no arg */
			place = EMSG;
			if (*ostr == ':')
				return (BADARG);
			if (opterr)
				(void)printf("option requires an argument -- %c\n", optopt);
			return (BADCH);
		}
		else                            /* white space */
			optarg = nargv[optind];
		place = EMSG;
		++optind;
	}
	return (optopt);                        /* dump back option letter */
}

#endif // !GETOPT_H_