distr/util/getopt.c

   1 /* LINTLIBRARY */
   2
   3 #include <stdio.h>
   4 #include "util.h"
   5
   6
   7 /*  File   : getopt.c
   8  *  Author : Henry Spencer, University of Toronto
   9  *  Updated: 28 April 1984
  10  *
  11  *  Changes: (R Rudell)
  12  *      changed index() to strchr();
  13  *      added getopt_reset() to reset the getopt argument parsing
  14  *
  15  *  Purpose: get option letter from argv.
  16  */
  17
  18 char *util_optarg;      /* Global argument pointer. */
  19 int util_optind = 0;    /* Global argv index. */
  20 static char *scan;
  21
  22
  23 void
  24 util_getopt_reset()
  25 {
  26     util_optarg = 0;
  27     util_optind = 0;
  28     scan = 0;
  29 }
  30
  31
  32
  33 int
  34 util_getopt(int argc, char * const argv[], char const *optstring)
  35 {
  36     register int c;
  37     register char *place;
  38
  39     util_optarg = NIL(char);
  40
  41     if (scan == NIL(char) || *scan == '\0') {
  42         if (util_optind == 0) util_optind++;
  43         if (util_optind >= argc) return EOF;
  44         place = argv[util_optind];
  45         if (place[0] != '-' || place[1] == '\0') return EOF;
  46         util_optind++;
  47         if (place[1] == '-' && place[2] == '\0') return EOF;
  48         scan = place+1;
  49     }
  50
  51     c = *scan++;
  52     place = strchr(optstring, c);
  53     if (place == NIL(char) || c == ':') {
  54         (void) fprintf(stderr, "%s: unknown option %c\n", argv[0], c);
  55         return '?';
  56     }
  57     if (*++place == ':') {
  58         if (*scan != '\0') {
  59             util_optarg = scan;
  60             scan = NIL(char);
  61         } else {
  62             if (util_optind >= argc) {
  63                 (void) fprintf(stderr, "%s: %c requires an argument\n",
  64                     argv[0], c);
  65                 return '?';
  66             }
  67             util_optarg = argv[util_optind];
  68             util_optind++;
  69         }
  70     }
  71     return c;
  72 }