wp_kses_attr_check( string $name, string $value, string $whole, string $vless, string $element, array $allowed_html ): bool

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$namestring

The attribute name. Passed by reference. Returns empty string when not allowed.

$valuestring

The attribute value. Passed by reference. Returns a filtered value.

$wholestring

The name=value input. Passed by reference. Returns filtered input.

$vlessstring

Whether the attribute is valueless. Use 'y' or 'n'.

$elementstring

The name of the element to which this attribute belongs.

$allowed_htmlarray

The full list of allowed elements and attributes.

Return value

bool

Whether or not the attribute is allowed.

Performance profile

How much work a call to wp_kses_attr_check() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Light

Touches nothing outside its own arguments.

Scaling

Scales with input

The body loops, so the work grows with what you pass in.

Instructions

20–78

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 92.

Plugin surface

None

Nothing here hands control to plugin code.

Called by

2

2 places in core call this, so the cost is paid more often than your own code shows.

What it touches

• hookthird-party callbacksapply_filters()one call below wp_kses_attr_check()

Further down the call graph this can also reach option, cache, serialize, query and transient. Those are the worst case, several calls deep and usually down an error path, not what a normal call pays.

What one call costs · 12 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost wp_kses_attr_check() can have, taken from its control-flow graph on PHP 8.5.

Uses · 5

• str_starts_with()Polyfill for `str_starts_with()` function added in PHP 8.0.
• safecss_filter_attr()Filters an inline style attribute and removes disallowed rules.
• esc_attr()Escaping for HTML attributes.
• wp_kses_check_attr_val()Performs different checks for attribute values.
• WP_HTML_Decoder::decode_attribute()Returns a string containing the decoded value of a given HTML attribute.

Used by · 2

• wp_kses_attr()Removes all attributes, if none are allowed for this element.
• wp_kses_one_attr()Filters one HTML attribute and ensures its value is allowed.

Source code

View on Trac ↗View on GitHub ↗

1605function wp_kses_attr_check( &$name, &$value, &$whole, $vless, $element, $allowed_html ) {1606	$name_low    = strtolower( $name );1607	$element_low = strtolower( $element );1608 1609	if ( ! isset( $allowed_html[ $element_low ] ) ) {1610		$name  = '';1611		$value = '';1612		$whole = '';1613		return false;1614	}1615 1616	$allowed_attr = $allowed_html[ $element_low ];1617 1618	if ( ! isset( $allowed_attr[ $name_low ] ) || '' === $allowed_attr[ $name_low ] ) {1619		/*1620		 * Allow `data-*` attributes.1621		 *1622		 * When specifying `$allowed_html`, the attribute name should be set as1623		 * `data-*` (not to be mixed with the HTML 4.0 `data` attribute, see1624		 * https://www.w3.org/TR/html40/struct/objects.html#adef-data).1625		 *1626		 * Note: the attribute name should only contain `A-Za-z0-9_-` chars.1627		 */1628		if ( str_starts_with( $name_low, 'data-' ) && ! empty( $allowed_attr['data-*'] )1629			&& preg_match( '/^data-[a-z0-9_-]+$/', $name_low, $match )1630		) {1631			/*1632			 * Add the whole attribute name to the allowed attributes and set any restrictions1633			 * for the `data-*` attribute values for the current element.1634			 */1635			$allowed_attr[ $match[0] ] = $allowed_attr['data-*'];1636		} else {1637			$name  = '';1638			$value = '';1639			$whole = '';1640			return false;1641		}1642	}1643 1644	if ( 'style' === $name_low ) {1645		$decoded_value = WP_HTML_Decoder::decode_attribute( $value );1646		$new_value     = safecss_filter_attr( $decoded_value );1647 1648		if ( empty( $new_value ) ) {1649			$name  = '';1650			$value = '';1651			$whole = '';1652			return false;1653		}1654 1655		if ( $new_value !== $decoded_value ) {1656			$encoded_value = esc_attr( $new_value );1657			$whole         = str_replace( $value, $encoded_value, $whole );1658			$value         = $encoded_value;1659		}1660	}1661 1662	if ( is_array( $allowed_attr[ $name_low ] ) ) {1663		// There are some checks.1664		foreach ( $allowed_attr[ $name_low ] as $currkey => $currval ) {1665			if ( ! wp_kses_check_attr_val( $value, $vless, $currkey, $currval ) ) {1666				$name  = '';1667				$value = '';1668				$whole = '';1669				return false;1670			}1671		}1672	}1673 1674	return true;1675}

Changelog

Introduced in 4.2.3. Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data

Generated from the wordpress-develop 7.1.0 tag, from src/wp-includes/kses.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

Corrections

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