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function is not described

wp_kses_check_attr_val() WP 1.0.0

Performs different checks for attribute values.

The currently implemented checks are "maxlen", "minlen", "maxval", "minval" and "valueless".

No Hooks.

Return

true/false. Whether check passes

Usage

wp_kses_check_attr_val( $value, $vless, $checkname, $checkvalue );
$value(string) (required)
Attribute value
$vless(string) (required)
Whether the value is valueless. Use 'y' or 'n'
$checkname(string) (required)
What $checkvalue is checking for.
$checkvalue(mixed) (required)
What constraint the value should pass

Code of wp kses check attr val: wp-includes/kses.php VER 5.0.3

<?php
function wp_kses_check_attr_val($value, $vless, $checkname, $checkvalue) {
	$ok = true;

	switch (strtolower($checkname)) {
		case 'maxlen' :
			// The maxlen check makes sure that the attribute value has a length not
			// greater than the given value. This can be used to avoid Buffer Overflows
			// in WWW clients and various Internet servers.

			if (strlen($value) > $checkvalue)
				$ok = false;
			break;

		case 'minlen' :
			// The minlen check makes sure that the attribute value has a length not
			// smaller than the given value.

			if (strlen($value) < $checkvalue)
				$ok = false;
			break;

		case 'maxval' :
			// The maxval check does two things: it checks that the attribute value is
			// an integer from 0 and up, without an excessive amount of zeroes or
			// whitespace (to avoid Buffer Overflows). It also checks that the attribute
			// value is not greater than the given value.
			// This check can be used to avoid Denial of Service attacks.

			if (!preg_match('/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value))
				$ok = false;
			if ($value > $checkvalue)
				$ok = false;
			break;

		case 'minval' :
			// The minval check makes sure that the attribute value is a positive integer,
			// and that it is not smaller than the given value.

			if (!preg_match('/^\s{0,6}[0-9]{1,6}\s{0,6}$/', $value))
				$ok = false;
			if ($value < $checkvalue)
				$ok = false;
			break;

		case 'valueless' :
			// The valueless check makes sure if the attribute has a value
			// (like <a href="blah">) or not (<option selected>). If the given value
			// is a "y" or a "Y", the attribute must not have a value.
			// If the given value is an "n" or an "N", the attribute must have one.

			if (strtolower($checkvalue) != $vless)
				$ok = false;
			break;
	} // switch

	return $ok;
}