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WordPress

_wp_scrub_utf8_fallback( string $bytes ): string

Since
6.9.0
Source
wp-includes/compat-utf8.php:287
Fallback mechanism for replacing invalid spans of UTF-8 bytes.

Description

Example:

'Pi�a' === _wp_scrub_utf8_fallback( "Pi\xF1a" ); // “ñ” is 0xF1 in Windows-1252.

Compatibility

WordPress
since 6.9.0
PHP
7.4–8.6-dev
  • 6.7.7
  • 6.8.8
  • 6.9.7
  • 7.0.4
  • 7.1.0

Present in 3 of the 5 tracked releases, added in 6.9.0, and compiles on PHP 7.4 through 8.6-dev.

Parameters

$bytesstring
UTF-8 encoded string which might contain spans of invalid bytes.

Return value

string
Input string with spans of invalid bytes swapped with the replacement character.

Performance profile

How much work a call to _wp_scrub_utf8_fallback() 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
10–24

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 34.

Plugin surface
None

Nothing here hands control to plugin code.

Called by
1

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

What one call costs · 2 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost _wp_scrub_utf8_fallback() can have, taken from its control-flow graph on PHP 8.5.

WhenInstructionsCalls it makes
!$next_byte_at10none
$next_byte_at && $bytes_length20–24_wp_scan_utf8()

Across PHP versions

PHPCompiledExecutedBranchesNotes
8.6-dev3410–243
8.53410–243
8.43410–2436 fewer instructions than PHP 8.3
8.34010–273
8.24010–273
8.14010–273
7.44010–273

An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.

Uses · 1

  • _wp_scan_utf8()Finds spans of valid and invalid UTF-8 bytes in a given string.

Used by · 1

  • wp_scrub_utf8()Replaces ill-formed UTF-8 byte sequences with the Unicode Replacement Character.

Source code

View on Trac View on GitHub 

function _wp_scrub_utf8_fallback( string $bytes ): string {	$bytes_length   = strlen( $bytes );	$next_byte_at   = 0;	$was_at         = 0;	$invalid_length = 0;	$scrubbed       = ''; 	while ( $next_byte_at <= $bytes_length ) {		_wp_scan_utf8( $bytes, $next_byte_at, $invalid_length ); 		if ( $next_byte_at >= $bytes_length ) {			if ( 0 === $was_at ) {				return $bytes;			} 			return $scrubbed . substr( $bytes, $was_at, $next_byte_at - $was_at - $invalid_length );		} 		$scrubbed .= substr( $bytes, $was_at, $next_byte_at - $was_at );		$scrubbed .= "\u{FFFD}"; 		$next_byte_at += $invalid_length;		$was_at        = $next_byte_at;	} 	return $scrubbed;}

Changelog

Introduced in 6.9.0. Unchanged from 6.9.7 through 7.1.0.

  1. 6.9.7
  2. 7.0.4
  3. 7.1.0

Signature, return type and hooks compared across 3 parsed releases.

About this page

Parsed data
Generated from the wordpress-develop 7.1.0 tag, from src/wp-includes/compat-utf8.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
Corrections
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