wp_kses_check_attr_val( string $value, string $vless, string $checkname, mixed $checkvalue )

对属性值执行不同的检查。
Performs different checks for attribute values.

目录锚点：#说明#参数#源码

说明（Description）

当前执行的检查是“maxlen”、“minlen”、“maxval”、“minval”和“valueless”。

参数（Parameters）

源码（Source）

/**
 * Performs different checks for attribute values.
 *
 * The currently implemented checks are "maxlen", "minlen", "maxval", "minval"
 * and "valueless".
 *
 * @since 1.0.0
 *
 * @param string $value      Attribute value
 * @param string $vless      Whether the value is valueless. Use 'y' or 'n'
 * @param string $checkname  What $checkvalue is checking for.
 * @param mixed  $checkvalue What constraint the value should pass
 * @return bool Whether check passes
 */
function wp_kses_check_attr_val($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="">) or not (). 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;
}