Function utf8_strnwidth

utf8.c:211–234

* Returns the total number of columns required by a null-terminated * string, assuming that the string is utf8. Returns strlen() instead * if the string does not look like a valid utf8 string. */

 * if the string does not look like a valid utf8 string.
 */
int utf8_strnwidth(const char *string, size_t len, int skip_ansi)
{
	const char *orig = string;
	size_t width = 0;

	while (string && string < orig + len) {
		int glyph_width;
		size_t skip;

		while (skip_ansi &&
		       (skip = display_mode_esc_sequence_len(string)) != 0)
			string += skip;

		glyph_width = utf8_width(&string, NULL);
		if (glyph_width > 0)
			width += glyph_width;
	}

	/*
	 * TODO: fix the interface of this function and `utf8_strwidth()` to
	 * return `size_t` instead of `int`.
	 */
	return cast_size_t_to_int(string ? width : len);
}

int utf8_strwidth(const char *string)
{