source: azure_iot_hub/trunk/musl-1.1.18/src/multibyte/mbrlen.c@ 389

#include <wchar.h>

size_t mbrlen(const char *restrict s, size_t n, mbstate_t *restrict st)
{
        static unsigned internal;
        return mbrtowc(0, s, n, st ? st : (mbstate_t *)&internal);
}