xref: /third_party/libcoap/examples/getopt.c

/*
 * This file was copied from the following newsgroup posting:
 *
 * Newsgroups: mod.std.unix
 * Subject: public domain AT&T getopt source
 * Date: 3 Nov 85 19:34:15 GMT
 *
 * Here's something you've all been waiting for:  the AT&T public domain
 * source for getopt(3).  It is the code which was given out at the 1985
 * UNIFORUM conference in Dallas.  I obtained it by electronic mail
 * directly from AT&T.  The people there assure me that it is indeed
 * in the public domain.
 */

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

static int optind = 1;
static int optopt;
static char *optarg;

static int
getopt(int argc, char *argv[], const char *opts) {
  static int sp = 1;
  int c;
  char *cp;

  if (sp == 1) {
    if (optind >= argc ||
        argv[optind][0] != '-' || argv[optind][1] == '\0')
      return EOF;
    else if (!strcmp(argv[optind], "--")) {
      optind++;
      return EOF;
    }
  }
  optopt = c = argv[optind][sp];
  if (c == ':' || !(cp = strchr(opts, c))) {
    fprintf(stderr, ": illegal option -- %c\n", c);
    if (argv[optind][++sp] == '\0') {
      optind++;
      sp = 1;
    }
    return '?';
  }
  if (*++cp == ':') {
    if (argv[optind][sp+1] != '\0')
      optarg = &argv[optind++][sp+1];
    else if (++optind >= argc) {
      fprintf(stderr, ": option requires an argument -- %c\n", c);
      sp = 1;
      return '?';
    } else
      optarg = argv[optind++];
    sp = 1;
  } else {
    if (argv[optind][++sp] == '\0') {
      sp = 1;
      optind++;
    }
    optarg = NULL;
  }

  return c;
}