libxml_use_internal_errors - PHP code example

The php Function libxml_use_Internal_Errors

The php function libxml_use_internal_errors is an important tool for any PHP developer working with XML documents. This function disables the standard libxml errors and allows you to handle errors more flexibly in your code. In this article, we will look at how to use the libxml_use_internal_errors function and see some examples of how it works in practice.

XML is a mark-up language that you can use to describe data in a web page or application. It’s used to share information between programs and servers or between different systems. This information can be either human or machine read.

When an XML file or string is loaded in PHP, the parser looks for the right tags and values in the document to create an object that represents the XML. It’s important to note that if there is a syntax error in the XML, the PHP program will generate an error message. This can be very disruptive to your application.

However, if you use the libxml_use_internal_errors() function, the errors that occur while loading the XML file or string will be saved in an internal error buffer instead of being immediately displayed to the user. This makes it easier to troubleshoot problems in your code and fix them. The libxml_use_internal_errors() is a built-in function that first appeared in the PHP 5 release and works with all later versions of the language. It takes a boolean argument, which when passed TRUE enables the internal error handling and when passed FALSE disables it.

libxml_use_internal_errors example

XLIFF;

        $catalogue = $loader->load($resource, 'en', 'domain1');

        $this->assertEquals('en', $catalogue->getLocale());
        $this->assertSame([], libxml_get_errors());
        $this->assertContainsOnly('string', $catalogue->all('domain1'));
    }

    public function testLoadWithInternalErrorsEnabled()
    {
        $internalErrors = libxml_use_internal_errors(true);

        $this->assertSame([], libxml_get_errors());

        $loader = new XliffFileLoader();
        $resource = __DIR__.'/../fixtures/resources.xlf';
        $catalogue = $loader->load($resource, 'en', 'domain1');

        $this->assertEquals('en', $catalogue->getLocale());
        $this->assertEquals([new FileResource($resource)], $catalogue->getResources());
        $this->assertSame([], libxml_get_errors());

    private function validate(string $content, string $file = null): array
    {
        $errors = [];

        // Avoid: Warning DOMDocument::loadXML(): Empty string supplied as input         if ('' === trim($content)) {
            return ['file' => $file, 'valid' => true];
        }

        $internal = libxml_use_internal_errors(true);

        $document = new \DOMDocument();
        $document->loadXML($content);

        if (null !== $targetLanguage = $this->getTargetLanguageFromFile($document)) {
            $normalizedLocalePattern = sprintf('(%s|%s)', preg_quote($targetLanguage, '/'), preg_quote(str_replace('-', '_', $targetLanguage), '/'));
            // strict file names require translation files to be named '____.locale.xlf'             // otherwise, both '____.locale.xlf' and 'locale.____.xlf' are allowed             // also, the regexp matching must be case-insensitive, as defined for 'target-language' values             // http://docs.oasis-open.org/xliff/v1.2/os/xliff-core.html#target-language             $expectedFilenamePattern = $this->requireStrictFileNames ? sprintf('/^.*\.(?i:%s)\.(?:xlf|xliff)/', $normalizedLocalePattern) : sprintf('/^(?:.*\.(?i:%s)|(?i:%s)\..*)\.(?:xlf|xliff)/', $normalizedLocalePattern, $normalizedLocalePattern);

$this->assertContains((string) $element->attributes()->id, $elementsId);
        }
    }

    /** @dataProvider getHtmlIdsTestData */
    public function testHtmlIds($css, array $elementsId)
    {
        $translator = new Translator();
        $translator->registerExtension(new HtmlExtension($translator));
        $document = new \DOMDocument();
        $document->strictErrorChecking = false;
        $internalErrors = libxml_use_internal_errors(true);
        $document->loadHTMLFile(__DIR__.'/Fixtures/ids.html');
        $document = simplexml_import_dom($document);
        $elements = $document->xpath($translator->cssToXPath($css));
        $this->assertCount(\count($elementsId), $elements);
        foreach ($elements as $element) {
            if (null !== $element->attributes()->id) {
                $this->assertContains((string) $element->attributes()->id, $elementsId);
            }
        }
        libxml_clear_errors();
        libxml_use_internal_errors($internalErrors);
    }

  protected function validateHtml(string $body, string $id) {
    $doc = new \DOMDocument();
    $doc->strictErrorChecking = TRUE;
    $doc->validateOnParse = FALSE;
    libxml_use_internal_errors(TRUE);
    if (!$doc->loadXML('<html><body>' . $body . '</body></html>')) {
      foreach (libxml_get_errors() as $error) {
        $this->fail('Topic ' . $id . ' fails HTML validation: ' . $error->message);
      }

      libxml_clear_errors();
    }

    // Check for headings hierarchy.     $levels = [1, 2, 3, 4, 5, 6];
    foreach ($levels as $level) {

  protected function transformRootRelativeUrlsToAbsolute($rss_markup, Request $request) {
    $rss_dom = new \DOMDocument();

    // Load the RSS, if there are parsing errors, abort and return the unchanged     // markup.     $previous_value = libxml_use_internal_errors(TRUE);
    $rss_dom->loadXML($rss_markup);
    $errors = libxml_get_errors();
    libxml_use_internal_errors($previous_value);
    if ($errors) {
      return $rss_markup;
    }

    // Invoke Html::transformRootRelativeUrlsToAbsolute() on all HTML content     // embedded in this RSS feed.     foreach ($rss_dom->getElementsByTagName('description') as $node) {
      $html_markup = $node->nodeValue;

$base_obj->name = $name;
        $base_obj->access_path = $access_path;

        $r = new Representation('XML');
        $r->contents = $this->parser->parse($xml, $base_obj);

        $o->addRepresentation($r, 0);
    }

    protected static function xmlToSimpleXML(string $var, ?string $parent_path): ?array
    {
        $errors = \libxml_use_internal_errors(true);
        try {
            $xml = \simplexml_load_string($var);
        } catch (Exception $e) {
            return null;
        } finally {
            \libxml_use_internal_errors($errors);
        }

        if (false === $xml) {
            return null;
        }

        return $dom->saveXML($ignorePiNode ? $dom->documentElement : null, $context[self::SAVE_OPTIONS] ?? $this->defaultContext[self::SAVE_OPTIONS]);
    }

    public function decode(string $data, string $format, array $context = []): mixed
    {
        if ('' === trim($data)) {
            throw new NotEncodableValueException('Invalid XML data, it cannot be empty.');
        }

        $internalErrors = libxml_use_internal_errors(true);
        libxml_clear_errors();

        $dom = new \DOMDocument();
        $dom->loadXML($data, $context[self::LOAD_OPTIONS] ?? $this->defaultContext[self::LOAD_OPTIONS]);

        libxml_use_internal_errors($internalErrors);

        if ($error = libxml_get_last_error()) {
            libxml_clear_errors();

            throw new NotEncodableValueException($error->message);
        }

// In the rare case that DOMDocument is not available we cannot reliably sniff content and so we assume legacy.         if ( ! class_exists( 'DOMDocument' ) ) {
            // @codeCoverageIgnoreStart             return true;
            // @codeCoverageIgnoreEnd         }

        $doc = new DOMDocument();

        // Suppress warnings generated by loadHTML.         $errors = libxml_use_internal_errors( true );
        // phpcs:ignore WordPress.PHP.NoSilencedErrors.Discouraged         @$doc->loadHTML(
            sprintf(
                '<!DOCTYPE html><html><head><meta charset="%s"></head><body>%s</body></html>',
                esc_attr( get_bloginfo( 'charset' ) ),
                $instance['text']
            )
        );
        libxml_use_internal_errors( $errors );

        $body = $doc->getElementsByTagName( 'body' )->item( 0 );

return $this->translator->getLocale();
    }

    private function getParts(string $originalTrans): array
    {
        if (!$this->parseHTML) {
            return [[true, true, $originalTrans]];
        }

        $html = mb_encode_numericentity($originalTrans, [0x80, 0xFFFF, 0, 0xFFFF], mb_detect_encoding($originalTrans, null, true) ?: 'UTF-8');

        $useInternalErrors = libxml_use_internal_errors(true);

        $dom = new \DOMDocument();
        $dom->loadHTML('<trans>'.$html.'</trans>');

        libxml_clear_errors();
        libxml_use_internal_errors($useInternalErrors);

        return $this->parseNode($dom->childNodes->item(1)->childNodes->item(0)->childNodes->item(0));
    }

    private function parseNode(\DOMNode $node): array
    {

  protected function parseResourceXml($data, $url) {
    // Enable userspace error handling.     $was_using_internal_errors = libxml_use_internal_errors(TRUE);
    libxml_clear_errors();

    $content = simplexml_load_string($data, 'SimpleXMLElement', LIBXML_NOCDATA);
    // Restore the previous error handling behavior.     libxml_use_internal_errors($was_using_internal_errors);

    $error = libxml_get_last_error();
    if ($error) {
      libxml_clear_errors();
      throw new ResourceException($error->message, $url);
    }

namespace Symfony\Component\DomCrawler\Tests;

class NativeParserCrawlerTest extends AbstractCrawlerTestCase
{
    public static function getDoctype(): string
    {
        return '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">';
    }

    public function testAddHtmlContentWithErrors()
    {
        $internalErrors = libxml_use_internal_errors(true);

        $crawler = $this->createCrawler();
        $crawler->addHtmlContent(<<<'EOF' <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html> <head> </head> <body> <nav><a href="#"><a href="#"></nav> </body> </html>

$this->expectExceptionMessage('The XML is not valid');
        $fixtures = __DIR__.'/../Fixtures/Util/';

        $mock = $this->createMock(Validator::class);
        $mock->expects($this->once())->method('validate')->willReturn(false);

        XmlUtils::parse(file_get_contents($fixtures.'valid.xml'), [$mock, 'validate']);
    }

    public function testLoadFileWithInternalErrorsEnabled()
    {
        $internalErrors = libxml_use_internal_errors(true);

        $this->assertSame([], libxml_get_errors());
        $this->assertInstanceOf(\DOMDocument::class, XmlUtils::loadFile(__DIR__.'/../Fixtures/Util/invalid_schema.xml'));
        $this->assertSame([], libxml_get_errors());

        libxml_clear_errors();
        libxml_use_internal_errors($internalErrors);
    }

    /** * @dataProvider getDataForConvertDomToArray */

    public function addXmlContent(string $content, string $charset = 'UTF-8', int $options = \LIBXML_NONET)
    {
        // remove the default namespace if it's the only namespace to make XPath expressions simpler         if (!str_contains($content, 'xmlns:')) {
            $content = str_replace('xmlns', 'ns', $content);
        }

        $internalErrors = libxml_use_internal_errors(true);

        $dom = new \DOMDocument('1.0', $charset);
        $dom->validateOnParse = true;

        if ('' !== trim($content)) {
            @$dom->loadXML($content, $options);
        }

        libxml_use_internal_errors($internalErrors);

        $this->addDocument($dom);

    public static function parse(string $content, string|callable $schemaOrCallable = null): \DOMDocument
    {
        if (!\extension_loaded('dom')) {
            throw new \LogicException('Extension DOM is required.');
        }

        $internalErrors = libxml_use_internal_errors(true);
        libxml_clear_errors();

        $dom = new \DOMDocument();
        $dom->validateOnParse = true;
        if (!$dom->loadXML($content, \LIBXML_NONET | \LIBXML_COMPACT)) {
            throw new XmlParsingException(implode("\n", static::getXmlErrors($internalErrors)));
        }

        $dom->normalizeDocument();

        libxml_use_internal_errors($internalErrors);

if (!file_exists($resource)) {
            throw new NotFoundResourceException(sprintf('File "%s" not found.', $resource));
        }

        try {
            $dom = XmlUtils::loadFile($resource);
        } catch (\InvalidArgumentException $e) {
            throw new InvalidResourceException(sprintf('Unable to load "%s".', $resource), $e->getCode(), $e);
        }

        $internalErrors = libxml_use_internal_errors(true);
        libxml_clear_errors();

        $xpath = new \DOMXPath($dom);
        $nodes = $xpath->evaluate('//TS/context/name[text()="'.$domain.'"]');

        $catalogue = new MessageCatalogue($locale);
        if (1 == $nodes->length) {
            $translations = $nodes->item(0)->nextSibling->parentNode->parentNode->getElementsByTagName('message');
            foreach ($translations as $translation) {
                $translationValue = (string) $translation->getElementsByTagName('translation')->item(0)->nodeValue;