/*
 * Copyright (c) 1987, 1993, 1994
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <getopt.h>

#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

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

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

int getopt(int nargc, char* const nargv[], const char* ostr)
{
    static const char* place = EMSG; /* option letter processing */
    char *oli; /* option letter list index */

    ASSERT(nargv != NULL);
    ASSERT(ostr != NULL);

    if (optreset || !*place) { /* update scanning pointer */
        optreset = 0;
        if (optind >= nargc || *(place = nargv[optind]) != '-') {
            place = EMSG;
            return (-1);
        }
        if (place[1] && *++place == '-' /* found "--" */
            && place[1] == '\0') {
            ++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 != ':')
            fprintf(stderr, "unknown 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 = (char*)place;
        else if (nargc <= ++optind) { /* no arg */
            place = EMSG;
            if (*ostr == ':')
                return BADARG;
            if (opterr)
                fprintf(stderr, "option requires an argument -- %c\n", optopt);
            return BADCH;
        }
        else /* white space */
            optarg = nargv[optind];
        place = EMSG;
        ++optind;
    }
    return optopt; /* dump back option letter */
}