ext_localconf.php

<?php

if (!defined('TYPO3_MODE')) {
    die('Access denied.');
}

call_user_func(function () {
    /*
     * SVG sanitizer has been introduced to TYPO3 core
     * see https://review.typo3.org/c/Packages/TYPO3.CMS/+/69809
     *
     * skip hook registration (and handling by this extension in general)
     * in case corresponding handling class in TYPO3 core is available
     */
    if (class_exists(\TYPO3\CMS\Core\Resource\Security\SvgSanitizer::class)) {
        return;
    }

    $typo3Version = (defined('TYPO3_version'))
        ? TYPO3_version
        : \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(\TYPO3\CMS\Core\Information\Typo3Version::class)->getVersion();

    $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['TYPO3\CMS\Core\Utility\GeneralUtility']['moveUploadedFile'][]
        = \T3G\SvgSanitizer\Hooks\GeneralUtilityHook::class . '->processMoveUploadedFile';

    $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['ext/install']['update']['T3G\SvgSanitizer\Updates\SanitizeExistingSVG']
        = \T3G\SvgSanitizer\Updates\v8\SanitizeExistingSVG::class;

    if (\TYPO3\CMS\Core\Utility\VersionNumberUtility::convertVersionNumberToInteger($typo3Version) >= 9005000) {
        $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['ext/install']['update']['T3G\SvgSanitizer\Updates\SanitizeExistingSVG']
            = \T3G\SvgSanitizer\Updates\v9\SanitizeExistingSVG::class;
    }

    // The following hooks have been removed with v10:
    $GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['t3lib/class.t3lib_tcemain.php']['processUpload']['svg_sanitizer']
        = \T3G\SvgSanitizer\Hooks\DataHandlerHook::class;

    // The following hooks/signal have been deprecated in 10.2 and removed with v11:
    // As a replacement for the deprecated signals we introduced the according PSR-14 events.
    if (\TYPO3\CMS\Core\Utility\VersionNumberUtility::convertVersionNumberToInteger($typo3Version) < 1002000) {
        $signalSlotDispatcher = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(\TYPO3\CMS\Extbase\SignalSlot\Dispatcher::class);
        $signalSlotDispatcher
            ->connect(
                \TYPO3\CMS\Core\Resource\ResourceStorage::class,
                \TYPO3\CMS\Core\Resource\ResourceStorageInterface::SIGNAL_PreFileAdd,
                \T3G\SvgSanitizer\SignalSlot\ResourceStorage::class,
                \TYPO3\CMS\Core\Resource\ResourceStorageInterface::SIGNAL_PreFileAdd
            );
        $signalSlotDispatcher
            ->connect(
                \TYPO3\CMS\Core\Resource\ResourceStorage::class,
                \TYPO3\CMS\Core\Resource\ResourceStorageInterface::SIGNAL_PreFileReplace,
                \T3G\SvgSanitizer\SignalSlot\ResourceStorage::class,
                \TYPO3\CMS\Core\Resource\ResourceStorageInterface::SIGNAL_PreFileReplace
            );
        $signalSlotDispatcher
            ->connect(
                \TYPO3\CMS\Core\Resource\ResourceStorage::class,
                \TYPO3\CMS\Core\Resource\ResourceStorageInterface::SIGNAL_PostFileSetContents,
                \T3G\SvgSanitizer\SignalSlot\ResourceStorage::class,
                \TYPO3\CMS\Core\Resource\ResourceStorageInterface::SIGNAL_PostFileSetContents
            );
    }
});