Add a "fork" of musl as //fusl.

fusl/src/misc/getopt.c

+#include <unistd.h>
+#include <wchar.h>
+#include <string.h>
+#include <limits.h>
+#include <stdlib.h>
+#include "libc.h"
+#include "locale_impl.h"
+
+char *optarg;
+int optind=1, opterr=1, optopt, __optpos, __optreset=0;
+
+#define optpos __optpos
+weak_alias(__optreset, optreset);
+
+void __getopt_msg(const char *a, const char *b, const char *c, size_t l)
+{
+        FILE *f = stderr;
+        b = __lctrans_cur(b);
+        flockfile(f);
+        fwrite(a, strlen(a), 1, f)
+        && fwrite(b, strlen(b), 1, f)
+        && fwrite(c, l, 1, f)
+        && putc('\n', f);
+        funlockfile(f);
+}
+
+int getopt(int argc, char * const argv[], const char *optstring)
+{
+        int i;
+        wchar_t c, d;
+        int k, l;
+        char *optchar;
+
+        if (!optind || __optreset) {
+                __optreset = 0;
+                __optpos = 0;
+                optind = 1;
+        }
+
+        if (optind >= argc || !argv[optind])
+                return -1;
+
+        if (argv[optind][0] != '-') {
+                if (optstring[0] == '-') {
+                        optarg = argv[optind++];
+                        return 1;
+                }
+                return -1;
+        }
+
+        if (!argv[optind][1])
+                return -1;
+
+        if (argv[optind][1] == '-' && !argv[optind][2])
+                return optind++, -1;
+
+        if (!optpos) optpos++;
+        if ((k = mbtowc(&c, argv[optind]+optpos, MB_LEN_MAX)) < 0) {
+                k = 1;
+                c = 0xfffd; /* replacement char */
+        }
+        optchar = argv[optind]+optpos;
+        optopt = c;
+        optpos += k;
+
+        if (!argv[optind][optpos]) {
+                optind++;
+                optpos = 0;
+        }
+
+        if (optstring[0] == '-' || optstring[0] == '+')
+                optstring++;
+
+        i = 0;
+        d = 0;
+        do {
+                l = mbtowc(&d, optstring+i, MB_LEN_MAX);
+                if (l>0) i+=l; else i++;
+        } while (l && d != c);
+
+        if (d != c) {
+                if (optstring[0] != ':' && opterr)
+                        __getopt_msg(argv[0], ": unrecognized option: ", optchar, k);
+                return '?';
+        }
+        if (optstring[i] == ':') {
+                if (optstring[i+1] == ':') optarg = 0;
+                else if (optind >= argc) {
+                        if (optstring[0] == ':') return ':';
+                        if (opterr) __getopt_msg(argv[0],
+                                ": option requires an argument: ",
+                                optchar, k);
+                        return '?';
+                }
+                if (optstring[i+1] != ':' || optpos) {
+                        optarg = argv[optind++] + optpos;
+                        optpos = 0;
+                }
+        }
+        return c;
+}
+
+weak_alias(getopt, __posix_getopt);