xref: /third_party/libcoap/examples/getopt.c (revision c87c5fba)
1/*
2 * This file was copied from the following newsgroup posting:
3 *
4 * Newsgroups: mod.std.unix
5 * Subject: public domain AT&T getopt source
6 * Date: 3 Nov 85 19:34:15 GMT
7 *
8 * Here's something you've all been waiting for:  the AT&T public domain
9 * source for getopt(3).  It is the code which was given out at the 1985
10 * UNIFORUM conference in Dallas.  I obtained it by electronic mail
11 * directly from AT&T.  The people there assure me that it is indeed
12 * in the public domain.
13 */
14
15#include <stdio.h>
16#include <string.h>
17
18static int optind = 1;
19static int optopt;
20static char *optarg;
21
22static int
23getopt(int argc, char *argv[], const char *opts) {
24  static int sp = 1;
25  int c;
26  char *cp;
27
28  if (sp == 1) {
29    if (optind >= argc ||
30        argv[optind][0] != '-' || argv[optind][1] == '\0')
31      return EOF;
32    else if (!strcmp(argv[optind], "--")) {
33      optind++;
34      return EOF;
35    }
36  }
37  optopt = c = argv[optind][sp];
38  if (c == ':' || !(cp = strchr(opts, c))) {
39    fprintf(stderr, ": illegal option -- %c\n", c);
40    if (argv[optind][++sp] == '\0') {
41      optind++;
42      sp = 1;
43    }
44    return '?';
45  }
46  if (*++cp == ':') {
47    if (argv[optind][sp+1] != '\0')
48      optarg = &argv[optind++][sp+1];
49    else if (++optind >= argc) {
50      fprintf(stderr, ": option requires an argument -- %c\n", c);
51      sp = 1;
52      return '?';
53    } else
54      optarg = argv[optind++];
55    sp = 1;
56  } else {
57    if (argv[optind][++sp] == '\0') {
58      sp = 1;
59      optind++;
60    }
61    optarg = NULL;
62  }
63
64  return c;
65}
66