Fixes wrong replacements when having multibyte characters in tag attr…

[Erftralle]

…ibute values

I had a closer look to the problem with the "infinite loop" (which means that at the end you are running into the maximum execution time error) mentioned in joomla/joomla-cms#34967.

The problem is, that escapeAttributeValues() does not handle multibyte characters correctly. It makes wrong replacements in the tag attribute values which leads to the "infinite loop" in the further processing after the function has been applied.

One can reproduce the wrong replacement by doing the following changes to a fresch installation of Joomla 4.0.0

1. Change the access of the function protected function escapeAttributeValues($source) in /libraries/vendor/joomla/filter/src/InputFilter.php from protected to public.
2. Add the following code to line 179 of administrator/components/com_cpanel/src/View/Cpanel/HtmlView.php

		$inputFilter = \Joomla\CMS\Filter\InputFilter::getInstance(array(), array(), 1, 1);
		$testhtml = '<input alt="PayPal – The safer, easier way to pay online!" name="submit" src="https://www.paypalobjects.com/de_DE/CH/i/btn/btn_donateCC_LG.gif" type="image" />';

		echo "<p>Before applying escapeAttributeValues():<br/>";
		echo(htmlentities($testhtml));
		echo "</p>";
		echo "<p>After applying escapeAttributeValues():<br/>";
		echo(htmlentities($inputFilter->escapeAttributeValues($testhtml)));
		echo "</p>";

3. Open the Joomla 4 dashboard in the backend. Notice the hyphen in the "alt" attribute of the input tag, which is a multibyte character (3 bytes). See the wrong replacements ... online!" "ame=.

The problem is, that $matches[0][1] counts in bytes and $attributeValue = StringHelper::substr($remainder, $nextBefore, $nextAfter - $nextBefore); counts in multibyte characters.

After applying the patch there is no wrong replacement any more.

[MrMusic]

I have tested this item ✅ successfully.
Thank you very much.

[ryandemmer]

Thank you Erftralle

I can confirm that all tests using examples from my issue - joomla/joomla-cms#39193 - and other examples as reported to me, pass with this PR.

[MacJoom]

I have tested this item ✅ successfully. Coming from issue joomla/joomla-cms/issues/39193
Thank you

[richard67]

Hmm, if it shall go into Joomla 4, it should either be made for the 2.0-dev branch, or it has to be merged up from the 1.x-dev into the 2.0-dev branch after it has been merged.

[Hackwar]

I recreated the PR against 2.0-dev in #62. Since 1.0 doesn't get any support anymore, I'm closing this one.