source: azure_iot_hub/trunk/musl-1.1.18/src/string/wcsnlen.c@ 388

#include <wchar.h>

size_t wcsnlen(const wchar_t *s, size_t n)
{
        const wchar_t *z = wmemchr(s, 0, n);
        if (z) n = z-s;
        return n;
}