Function xo_strndup

tools/libxo/libxo/libxo.c:2476–2489

* strndup with a twist: len < 0 means len = strlen(str) */

 * strndup with a twist: len < 0 means len = strlen(str)
 */
static char *
xo_strndup (const char *str, ssize_t len)
{
    if (len < 0)
	len = strlen(str);

    char *cp = xo_realloc(NULL, len + 1);
    if (cp) {
	memcpy(cp, str, len);
	cp[len] = '\0';
    }

    return cp;
}

/**
 * Record a leading prefix for the XPath we generate.  This allows the