com32/lib/getopt.c

   1 /*
   2  * getopt.c
   3  *
   4  * Simple POSIX getopt(), no GNU extensions...
   5  */
   6
   7 #include <stdint.h>
   8 #include <unistd.h>
   9 #include <string.h>
  10
  11 char *optarg;
  12 int optind, opterr, optopt;
  13 static struct getopt_private_state {
  14         const char *optptr;
  15         const char *last_optstring;
  16         char *const *last_argv;
  17 } pvt;
  18
  19 int getopt(int argc, char *const *argv, const char *optstring)
  20 {
  21         const char *carg;
  22         const char *osptr;
  23         int opt;
  24
  25         /* getopt() relies on a number of different global state
  26            variables, which can make this really confusing if there is
  27            more than one use of getopt() in the same program.  This
  28            attempts to detect that situation by detecting if the
  29            "optstring" or "argv" argument have changed since last time
  30            we were called; if so, reinitialize the query state. */
  31
  32         if (optstring != pvt.last_optstring || argv != pvt.last_argv ||
  33             optind < 1 || optind > argc) {
  34                 /* optind doesn't match the current query */
  35                 pvt.last_optstring = optstring;
  36                 pvt.last_argv = argv;
  37                 optind = 1;
  38                 pvt.optptr = NULL;
  39         }
  40
  41         carg = argv[optind];
  42
  43         /* First, eliminate all non-option cases */
  44
  45         if (!carg || carg[0] != '-' || !carg[1]) {
  46                 return -1;
  47         }
  48
  49         if (carg[1] == '-' && !carg[2]) {
  50                 optind++;
  51                 return -1;
  52         }
  53
  54         if ((uintptr_t) (pvt.optptr - carg) > (uintptr_t) strlen(carg)) {
  55                 /* Someone frobbed optind, change to new opt. */
  56                 pvt.optptr = carg + 1;
  57         }
  58
  59         opt = *pvt.optptr++;
  60
  61         if (opt != ':' && (osptr = strchr(optstring, opt))) {
  62                 if (osptr[1] == ':') {
  63                         if (*pvt.optptr) {
  64                                 /* Argument-taking option with attached
  65                                    argument */
  66                                 optarg = (char *)pvt.optptr;
  67                                 optind++;
  68                         } else {
  69                                 /* Argument-taking option with non-attached
  70                                    argument */
  71                                 if (argv[optind + 1]) {
  72                                         optarg = (char *)argv[optind+1];
  73                                         optind += 2;
  74                                 } else {
  75                                         /* Missing argument */
  76                                         optind++;
  77                                         return (optstring[0] == ':')
  78                                                 ? ':' : '?';
  79                                 }
  80                         }
  81                         return opt;
  82                 } else {
  83                         /* Non-argument-taking option */
  84                         /* pvt.optptr will remember the exact position to
  85                            resume at */
  86                         if (!*pvt.optptr)
  87                                 optind++;
  88                         return opt;
  89                 }
  90         } else {
  91                 /* Unknown option */
  92                 optopt = opt;
  93                 if (!*pvt.optptr)
  94                         optind++;
  95                 return '?';
  96         }
  97 }