source: azure_iot_hub/trunk/musl-1.1.18/src/locale/newlocale.c@ 388

#include <stdlib.h>
#include <string.h>
#include "locale_impl.h"
#include "libc.h"

int __loc_is_allocated(locale_t loc)
{
        return loc && loc != C_LOCALE && loc != UTF8_LOCALE;
}

locale_t __newlocale(int mask, const char *name, locale_t loc)
{
        int i, j;
        struct __locale_struct tmp;
        const struct __locale_map *lm;

        /* For locales with allocated storage, modify in-place. */
        if (__loc_is_allocated(loc)) {
                for (i=0; i<LC_ALL; i++)
                        if (mask & (1<<i))
                                loc->cat[i] = __get_locale(i, name);
                return loc;
        }

        /* Otherwise, build a temporary locale object, which will only
         * be instantiated in allocated storage if it does not match
         * one of the built-in static locales. This makes the common
         * usage case for newlocale, getting a C locale with predictable
         * behavior, very fast, and more importantly, fail-safe. */
        for (j=i=0; i<LC_ALL; i++) {
                if (loc && !(mask & (1<<i)))
                        lm = loc->cat[i];
                else
                        lm = __get_locale(i, mask & (1<<i) ? name : "");
                if (lm) j++;
                tmp.cat[i] = lm;
        }

        if (!j)
                return C_LOCALE;
        if (j==1 && tmp.cat[LC_CTYPE]==&__c_dot_utf8)
                return UTF8_LOCALE;

        if ((loc = malloc(sizeof *loc))) *loc = tmp;

        return loc;
}

weak_alias(__newlocale, newlocale);