wcsnlen.c\string\src - musl - musl - an implementation of the standard library for Linux-based systems

#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;
}