/*  File   : getopt.c
 *  Author : Henry Spencer, University of Toronto
 *  Updated: 28 April 1984
 *
 *  Changes: (R Rudell)
 *	changed index() to strchr();
 *	added getopt_reset() to reset the getopt argument parsing
 *
 *  Purpose: get option letter from argv.
 */

#include <stdio.h>
#include "util.h"

char *util_optarg;	/* Global argument pointer. */
int util_optind = 0;	/* Global argv index. */
static char *scan;

void
util_getopt_reset()
{
    util_optarg = 0;
    util_optind = 0;
    scan = 0;
}

int 
util_getopt(
  int argc, 
  char **argv, 
  char *optstring
)
{
  int c;
  char *place;

  util_optarg = NIL(char);

  if ( scan == NIL(char) || *scan == '\0') {
    if ( util_optind == 0 ) {
      util_optind++;
    }
    if (util_optind >= argc) {
      return EOF;
    }
    place = argv[util_optind];
    if ( ( place[0] != '-' ) || ( place[1] == '\0') ) {
      return EOF;
    }
    util_optind++;
    if ( ( place[1] == '-' ) && ( place[2] == '\0' ) ) {
      return EOF;
    }
    scan = place+1;
  }

  c = *scan++;
  place = strchr(optstring, c);
  if ( ( place == NIL(char) ) || ( c == ':') ) {
    fprintf(stderr, "%s: unknown option %c\n", argv[0], c);
    return '?';
  }
  if (*++place == ':') {
    if (*scan != '\0') {
      util_optarg = scan;
      scan = NIL(char);
    } else {
      if (util_optind >= argc) {
	(void) fprintf(stderr, "%s: %c requires an argument\n", 
	argv[0], c);
	return '?';
      }
      util_optarg = argv[util_optind];
      util_optind++;
    }
  }
  return c;
}

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