getopt(3) in the Solaris way, as a wrapper around getopt_long(3)

sun_getopt.c

/**
 * sun_getopt - Solaris-style getopt(3), as a wrapper around getopt_long(3).
 * 
 * Written by Mingye Wang (Artoria2e5). Dedicated to the public domain under
 * Creative Commons Zero.
 *
 * Untested. Like not even fed to a compiler once.
 */

#include "sun_getopt.h"

#include <getopt.h>
#include <stddef.h>
#include <stdlib.h>

struct sun_longopts_s {
    const char *sun;
    char *posix;
    struct option *opts;
};

#if __STDC_VERSION__ >= 201112L
static _Thread_local sun_longopts_t store = {NULL, NULL, NULL};
#else
static sun_longopts_t store = {NULL, NULL, NULL};
#endif

static int sun_getopt_compile(const char *__restrict from, sun_longopts_t *__restrict to) {
    size_t len = strlen(from);
    size_t opt_count = 0;
    
    to->sun = from;
    to->posix = malloc(len + 1);
    if (!to->posix) return 0;
    
    size_t opt_size = 16;
    to->opts = malloc(opt_size * sizeof(struct option));
    if (!to->opts) return 0;
    
    int optchar = '\0';
    char *to_str = to->posix;
    const char* paren_start = NULL;
    size_t colons = 0;
    for (size_t i = 0; i < len; i++) {
        if (!paren_start) {
            if (from[i] == '(') {
                in_paren = 1;
                paren_start = &from[i];
                continue;
            }

            if (from[i] != ':') {
                colons = 0;
                optchar = from[i];
            } else {
                colons++;
            }
            
            // Maybe we should filter out unprintable optchars? So they can be used as indices but not short args.
            *to_str++ = from[i];
        } else if (from[i] == ')') {
            if (++opt_count >= opt_size - 1)
                if (!(to->opts = realloc(to->opts,
                                         (opt_size *= 2) * sizeof(struct option))))
                    return 0;
            to->opts[opt_count] = {
                strndup(paren_start + 1, &from[i] - paren_startn - 1),
                colons > 1 ? optional_argument : colon == 1 ? required_argument : no_argument,
                NULL,
                optchar
            };
            paren_start = NULL;
            colons = 0;
            optchar = '\0';
        }
    }

    *to_str = '\0';
    to->opts[++opt_count] = {NULL, 0, NULL, 0};
    return !paren_start;
}

int sun_getopt(int argc, char *const argv[], const char *optstring) {
    if (!store.posix || strcmp(store.sun, optstring)) {
        int status = sun_getopt_compile(optstring, &store);
        if (!status)
            return EOF; // FIXME
    }
    
    return getopt_long(argc, argv, store.posix, store.opts, NULL);
}

sun_getopt.h

/**
 * sun_getopt - Solaris-style getopt(3), as a wrapper around getopt_long(3).
 * 
 * Written by Mingye Wang (Artoria2e5). Dedicated to the public domain under
 * Creative Commons Zero.
 */

#ifndef SUN_GETOPT_H
#define SUN_GETOPT_H

extern char *optarg;
extern int optind;
extern int optopt;
extern int opterr;
#if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) || defined(__APPLE__)
extern int optreset;
#endif

typedef struct sun_longopts_s sun_longopts_t;

int sun_getopt(int argc, char *const argv[], const char *optstring);
void sun_getopt_finish()
#endif