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

fusl/src/locale/locale_map.c

+#include <locale.h>
+#include <string.h>
+#include "locale_impl.h"
+#include "libc.h"
+#include "atomic.h"
+
+const char *__lctrans_impl(const char *msg, const struct __locale_map *lm)
+{
+        const char *trans = 0;
+        if (lm) trans = __mo_lookup(lm->map, lm->map_size, msg);
+        return trans ? trans : msg;
+}
+
+const unsigned char *__map_file(const char *, size_t *);
+int __munmap(void *, size_t);
+char *__strchrnul(const char *, int);
+
+static const char envvars[][12] = {
+        "LC_CTYPE",
+        "LC_NUMERIC",
+        "LC_TIME",
+        "LC_COLLATE",
+        "LC_MONETARY",
+        "LC_MESSAGES",
+};
+
+const struct __locale_map *__get_locale(int cat, const char *val)
+{
+        static int lock[2];
+        static void *volatile loc_head;
+        const struct __locale_map *p;
+        struct __locale_map *new = 0;
+        const char *path = 0, *z;
+        char buf[256];
+        size_t l, n;
+
+        if (!*val) {
+                (val = getenv("LC_ALL")) && *val ||
+                (val = getenv(envvars[cat])) && *val ||
+                (val = getenv("LANG")) && *val ||
+                (val = "C.UTF-8");
+        }
+
+        /* Limit name length and forbid leading dot or any slashes. */
+        for (n=0; n<LOCALE_NAME_MAX && val[n] && val[n]!='/'; n++);
+        if (val[0]=='.' || val[n]) val = "C.UTF-8";
+        int builtin = (val[0]=='C' && !val[1])
+                || !strcmp(val, "C.UTF-8")
+                || !strcmp(val, "POSIX");
+
+        if (builtin) {
+                if (cat == LC_CTYPE && val[1]=='.')
+                        return (void *)&__c_dot_utf8;
+                return 0;
+        }
+
+        for (p=loc_head; p; p=p->next)
+                if (!strcmp(val, p->name)) return p;
+
+        LOCK(lock);
+
+        for (p=loc_head; p; p=p->next)
+                if (!strcmp(val, p->name)) {
+                        UNLOCK(lock);
+                        return p;
+                }
+
+        if (!libc.secure) path = getenv("MUSL_LOCPATH");
+        /* FIXME: add a default path? */
+
+        if (path) for (; *path; path=z+!!*z) {
+                z = __strchrnul(path, ':');
+                l = z - path - !!*z;
+                if (l >= sizeof buf - n - 2) continue;
+                memcpy(buf, path, l);
+                buf[l] = '/';
+                memcpy(buf+l+1, val, n);
+                buf[l+1+n] = 0;
+                size_t map_size;
+                const void *map = __map_file(buf, &map_size);
+                if (map) {
+                        new = malloc(sizeof *new);
+                        if (!new) {
+                                __munmap((void *)map, map_size);
+                                break;
+                        }
+                        new->map = map;
+                        new->map_size = map_size;
+                        memcpy(new->name, val, n);
+                        new->name[n] = 0;
+                        new->next = loc_head;
+                        loc_head = new;
+                        break;
+                }
+        }
+
+        /* If no locale definition was found, make a locale map
+         * object anyway to store the name, which is kept for the
+         * sake of being able to do message translations at the
+         * application level. */
+        if (!new && (new = malloc(sizeof *new))) {
+                new->map = __c_dot_utf8.map;
+                new->map_size = __c_dot_utf8.map_size;
+                memcpy(new->name, val, n);
+                new->name[n] = 0;
+                new->next = loc_head;
+                loc_head = new;
+        }
+
+        /* For LC_CTYPE, never return a null pointer unless the
+         * requested name was "C" or "POSIX". */
+        if (!new && cat == LC_CTYPE) new = (void *)&__c_dot_utf8;
+
+        UNLOCK(lock);
+        return new;
+}