NSS_BUFLEN_SHADOW
b = NSS_XbyY_ALLOC(&buffer, sizeof (struct spwd), NSS_BUFLEN_SHADOW);
char shadow[NSS_BUFLEN_SHADOW];
b = NSS_XbyY_ALLOC(buffer, sizeof (struct spwd), NSS_BUFLEN_SHADOW);
NSS_XbyY_ALLOC(&spbuf, sizeof (struct spwd), NSS_BUFLEN_SHADOW)