Fixes xsd schema to work with libxml 2.12 and higher.

[hostep]

Description (*)

The latest libxml2 library (2.12.*) contains more strict requirements for xsd schema files:

Several bugs in the regex determinism checks were fixed. Invalid XML Schemas which previous versions erroneously accepted will now be rejected.
Source: https://www.linuxcompatible.org/story/libxml2-2120-released/

There is one xsd file in Magento which now fails these more stricter checks: app/code/Magento/Elasticsearch/etc/esconfig.xsd

When using any Magento version with libxml2 version 2.12.* in developer mode, whenever an xml file with esconfig.xsd schema is being loaded, it will now fail with this error:

Exception #0 (Magento\Framework\Config\Dom\ValidationSchemaException): Processed schema file: vendor/magento/module-elasticsearch/etc/esconfig.xsd
complex type 'mixedDataType': The content model is not determinist.
Line: 18

This PR fixes this. It should be mostly backwards compatible. With the exception that it now always expect the type element to be in front of the default element in the stemmer section, but that matches how Magento's xml files are already setup:

• Magento/Elasticsearch/etc/esconfig.xml
• Magento/Elasticsearch/Test/Unit/Model/Adapter/Index/Config/_files/esconfig_test.xml

This PR fixes an additional problem - by splitting out the types for stemmer and stopwords_file. Previously, there was no requirement on type element, even though the code that parses this xml file requires the type to exist. That's been fixed by no longer using mixedDataType for both stemmer and stopwords_file elements, but splitting it out in 2 distinct types where the one for stemmer now requires a type element to exist.

I've tested these changes with libxml2 versions 2.9.14 and 2.12.6 and both work correctly.

Related Pull Requests

Fixed Issues (if relevant)

1. Fixes Catalog search index process error indexation process #38254

Manual testing scenarios (*)

1. Have php being compiled with libxml2 using a version lower than 2.12.0
2. Have a test-xsd.php file in the root of the magento project with this contents:

<?php

echo sprintf("Libxml version: %s\n\n", getLibXmlVersion());

$xmlFiles = [
    sprintf('%s/app/code/Magento/Elasticsearch/etc/esconfig.xml', __DIR__),
    sprintf('%s/app/code/Magento/Elasticsearch/Test/Unit/Model/Adapter/Index/Config/_files/esconfig_test.xml', __DIR__),
];
$schemaFile = sprintf('%s/app/code/Magento/Elasticsearch/etc/esconfig.xsd', __DIR__);

foreach ($xmlFiles as $xmlFile) {
    $xml = file_get_contents($xmlFile);

    $dom = new \DOMDocument();
    $dom->loadXML($xml);

    $result = $dom->schemaValidate($schemaFile);

    var_dump($result);
}

function getLibXmlVersion(): string
{
    $reflector = new \ReflectionExtension('libxml');
    ob_start();
    $reflector->info();
    $output = strip_tags(ob_get_clean());
    preg_match('/^libXML Loaded Version (?:=>)?(.*)$/m', $output, $matches);

    return $matches[1];
}

1. Execute that file via cli: php test-xsd.php, expected is to see no errors
2. Have php being compiled with libxml2 using a version higher than or equal to 2.12.0
3. Execute that file via cli: php test-xsd.php, expected is to see no errors

Alternative steps:

1. Have php being compiled with libxml2 using a version higher than or equal to 2.12.0
2. Have Magento run in developer mode
3. Run bin/magento indexer:reindex catalogsearch_fulltext, expect to get no errors

Questions or comments

I haven't found time or energy to add/update unit tests, if this is required, it would be appreciated if somebody could lend a hand.

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• README.md files for modified modules are updated and included in the pull request if any README.md predefined sections require an update
• All automated tests passed successfully (all builds are green)

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[hostep]

@magento run all tests

[engcom-Bravo]

Hi,

Internal team has started to work on it

Thanks.

[iphigenie]

just a friendly wave to say this works as a fix on 2.4.6-p5

[barryvdh]

Thanks, this works for me too

[hostep]

Looks like this got merged in 2.4-develop today: 0574ac2, yet this PR is not marked as merged ...

[ihor-sviziev]

The change was cherry-picked to 308e261 and merged to 2.4-develop branch, so we can close this PR