source: trunk/sys/dietlibc/getopt.c @ 50

#include <string.h>
#include <getopt.h>

static void getopterror(int which) {
  static char error1[]="Unknown option `-x'.\n";
  static char error2[]="Missing argument for `-x'.\n";
  if (opterr) {
    if (which) {
      error2[23]=optopt;
      write(2,error2,28);
    } else {
      error1[17]=optopt;
      write(2,error1,22);
    }
  }
}

int getopt(int argc, char * const argv[], const char *optstring) {
  static int lastidx,lastofs;
  char *tmp;
  if (optind==0) { optind=1; lastidx=0; }       /* whoever started setting optind to 0 should be shot */
again:
  if (optind>argc || !argv[optind] || *argv[optind]!='-' || argv[optind][1]==0)
    return -1;
  if (argv[optind][1]=='-' && argv[optind][2]==0) {
    ++optind;
    return -1;
  }
  if (lastidx!=optind) {
    lastidx=optind; lastofs=0;
  }
  optopt=argv[optind][lastofs+1];
  if ((tmp=strchr(optstring,optopt))) {
    if (*tmp==0) {      /* apparently, we looked for \0, i.e. end of argument */
      ++optind;
      goto again;
    }
    if (tmp[1]==':') {  /* argument expected */
      if (tmp[2]==':' || argv[optind][lastofs+2]) {     /* "-foo", return "oo" as optarg */
        if (!*(optarg=argv[optind]+lastofs+2)) optarg=0;
        goto found;
      }
      optarg=argv[optind+1];
      if (!optarg) {    /* missing argument */
        ++optind;
        if (*optstring==':') return ':';
        getopterror(1);
        return ':';
      }
      ++optind;
    } else {
      ++lastofs;
      return optopt;
    }
found:
    ++optind;
    return optopt;
  } else {      /* not found */
    getopterror(0);
    ++optind;
    return '?';
  }
}