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

20–68

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 82.

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 query, option, cache, serialize 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 · 8 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 · 3

• 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.
• wp_kses_check_attr_val()Performs different checks for attribute values.

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 ↗

1519function wp_kses_attr_check( &$name, &$value, &$whole, $vless, $element, $allowed_html ) {1520	$name_low    = strtolower( $name );1521	$element_low = strtolower( $element );1522 1523	if ( ! isset( $allowed_html[ $element_low ] ) ) {1524		$name  = '';1525		$value = '';1526		$whole = '';1527		return false;1528	}1529 1530	$allowed_attr = $allowed_html[ $element_low ];1531 1532	if ( ! isset( $allowed_attr[ $name_low ] ) || '' === $allowed_attr[ $name_low ] ) {1533		/*1534		 * Allow `data-*` attributes.1535		 *1536		 * When specifying `$allowed_html`, the attribute name should be set as1537		 * `data-*` (not to be mixed with the HTML 4.0 `data` attribute, see1538		 * https://www.w3.org/TR/html40/struct/objects.html#adef-data).1539		 *1540		 * Note: the attribute name should only contain `A-Za-z0-9_-` chars.1541		 */1542		if ( str_starts_with( $name_low, 'data-' ) && ! empty( $allowed_attr['data-*'] )1543			&& preg_match( '/^data-[a-z0-9_-]+$/', $name_low, $match )1544		) {1545			/*1546			 * Add the whole attribute name to the allowed attributes and set any restrictions1547			 * for the `data-*` attribute values for the current element.1548			 */1549			$allowed_attr[ $match[0] ] = $allowed_attr['data-*'];1550		} else {1551			$name  = '';1552			$value = '';1553			$whole = '';1554			return false;1555		}1556	}1557 1558	if ( 'style' === $name_low ) {1559		$new_value = safecss_filter_attr( $value );1560 1561		if ( empty( $new_value ) ) {1562			$name  = '';1563			$value = '';1564			$whole = '';1565			return false;1566		}1567 1568		$whole = str_replace( $value, $new_value, $whole );1569		$value = $new_value;1570	}1571 1572	if ( is_array( $allowed_attr[ $name_low ] ) ) {1573		// There are some checks.1574		foreach ( $allowed_attr[ $name_low ] as $currkey => $currval ) {1575			if ( ! wp_kses_check_attr_val( $value, $vless, $currkey, $currval ) ) {1576				$name  = '';1577				$value = '';1578				$whole = '';1579				return false;1580			}1581		}1582	}1583 1584	return true;1585}

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 6.9.7 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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