Function strlen_max_width

src/fe_utils/print.c:3624–3655

* Compute the byte distance to the end of the string or *target_width * display character positions, whichever comes first. Update *target_width * to be the number of display character positions actually filled. */

 * to be the number of display character positions actually filled.
 */
static int
strlen_max_width(unsigned char *str, int *target_width, int encoding)
{
	unsigned char *start = str;
	unsigned char *end = str + strlen((char *) str);
	int			curr_width = 0;

	while (str < end)
	{
		int			char_width = PQdsplen((char *) str, encoding);

		/*
		 * If the display width of the new character causes the string to
		 * exceed its target width, skip it and return.  However, if this is
		 * the first character of the string (curr_width == 0), we have to
		 * accept it.
		 */
		if (*target_width < curr_width + char_width && curr_width != 0)
			break;

		curr_width += char_width;

		str += PQmblen((char *) str, encoding);

		if (str > end)			/* Don't overrun invalid string */
			str = end;
	}

	*target_width = curr_width;

	return str - start;
}