Sets the mbstring internal encoding to a binary safe encoding when func_overload
is enabled.

When mbstring.func_overload is in use for multi-byte encodings, the results from
strlen() and similar functions respect the utf8 characters, causing binary data
to return incorrect lengths.

This function overrides the mbstring encoding to a binary-safe encoding, and
resets it to the users expected encoding afterwards through the
`reset_mbstring_encoding` function.

It is safe to recursively call this function, however each
`mbstring_binary_safe_encoding()` call must be followed up with an equal number
of `reset_mbstring_encoding()` calls.

function mbstring_binary_safe_encoding( $reset = false ) {
	static $encodings  = array();
	static $overloaded = null;

	if ( is_null( $overloaded ) ) {
		if ( function_exists( 'mb_internal_encoding' )
			&& ( (int) ini_get( 'mbstring.func_overload' ) & 2 ) // phpcs:ignore PHPCompatibility.IniDirectives.RemovedIniDirectives.mbstring_func_overloadDeprecated
		) {
			$overloaded = true;
		} else {
			$overloaded = false;
		}
	}

	if ( false === $overloaded ) {
		return;
	}

	if ( ! $reset ) {
		$encoding = mb_internal_encoding();
		array_push( $encodings, $encoding );
		mb_internal_encoding( 'ISO-8859-1' );
	}

	if ( $reset && $encodings ) {
		$encoding = array_pop( $encodings );
		mb_internal_encoding( $encoding );
	}
}