/* file getopt.c                                                   */
/*                Author: Peter Wilson                             */
/*                        Catholic University and NIST             */
/*                        pwilson@cme.nist.gov                     */
/*                                                                 */
/* getopt()  from Don Libes "Obfuscated C" */


#include <stdio.h>

/* getopt()  -- parse command line arguments */
/* Original Author: AT&T */
/* This version from Don Libes "Obfuscated C and Other Mysteries" */
/*  John Wiley & Sons, 1993. Chapter 6 */


#define ERR(s, c)    if(opterr){\
     char errbuf[2];\
     errbuf[0] = c; errbuf[1] = '\n';\
     fprintf(stderr, argv[0], (unsigned)strlen(argv[0]));\
     fprintf(stderr, s, (unsigned)strlen(s));\
     fprintf(stderr, errbuf, 2);}

extern int strcmp();
extern char *strchr();
extern int strlen();

int opterr = 1;    /* getopt prints errors if this is one */
int optind = 1;    /* token pointer */
int optopt;        /* option character passed back to user */
char *optarg;      /* flag argument (or value) */

int  /* return option option character, EOF if no more or ? if problem */
getopt(argc, argv, opts)
int argc;
char **argv;
char *opts;          /* option string */
{
    static int sp = 1;   /* character index in current token */
    register char *cp;   /* pointer into current token */

    if(sp == 1)
          /* check for more flag-like tokens */
          if(optind >= argc ||
             argv[optind][0] != '-' || argv[optind][1] == '\0')
               return(EOF);
          else if(strcmp(argv[optind], "--") == 0) {
               optind++;
               return(EOF);
	  }
    optopt = argv[optind][sp];
    if(optopt == ':' || (cp=strchr(opts, optopt)) == 0) {
         ERR(": illegal option -- ", optopt);
         /* if no chars left in this token, move to next token */
         if(argv[optind][++sp] == '\0') {
              optind++;
              sp = 1;
	 }
         return('?');
       }

       if(*++cp == ':') {/* if a value is expected, get it */
            if(argv[optind][sp+1] != '\0')
                 /* flag value is rest of current token */
                 optarg = &argv[optind++][sp+1];
            else if(++optind >= argc) {
                 ERR(": option requires an argument -- ", optopt);
                 sp = 1;
                 return('?');
	       } else
                    /* flag value is next token */
                    optarg = argv[optind++];
              sp = 1;
	  } else {
               /* set up to look at next char in token, next time */
               if(argv[optind][++sp] == '\0') {
                    /* no m ore in current token, set up next token */
                    sp = 1;
                    optind++;
		  }
               optarg = 0;
	     }
         return(optopt); /* return current flag character found */
  }