TYPO3 Core

Patch set 2 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at http://review.typo3.org/33955

Patch set 3 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at http://review.typo3.org/33955

Patch set 4 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at http://review.typo3.org/33955

Patch set 5 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at http://review.typo3.org/33955

Patch set 6 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at http://review.typo3.org/33955

Patch set 7 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at http://review.typo3.org/33955

Patch set 8 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at http://review.typo3.org/33955

The most basic ImportableDriver would just call addFile (untested):

<?php
namespace TYPO3\CMS\Core\Resource\Driver;

class LocalImportableDriver extends LocalDriver implements ImportableDriverInterface {
    /**
     * Add an already existing FAL File from another storage
     *
     * @param \TYPO3\CMS\Core\Resource\FileInterface $file
     * @param string $targetFolderIdentifier
     * @param string $newFileName optional, if not given original name is used
     * @return string The new identifier
     */
    public function importFile(\TYPO3\CMS\Core\Resource\FileInterface $file, $targetFolderIdentifier, $newFileName = NULL) {
        return $this->addFile(
            $file->getForLocalProcessing(FALSE),
            $targetFolderIdentifier,
            $newFileName,
            FALSE
        );
    }
}

A more sophisticated one, could download the files from another storage (untested):

<?php
namespace TYPO3\CMS\Core\Resource\Driver;

use TYPO3\CMS\Core\Utility\GeneralUtility;

class LocalImportableDriver extends LocalDriver implements ImportableDriverInterface {
    /**
     * Change to suit your host
     */
    const IMPORT_SOURCE_BASE = 'http://localhost';

    /**
     * Add an already existing FAL File from another storage
     *
     * @param \TYPO3\CMS\Core\Resource\FileInterface $file
     * @param string $targetFolderIdentifier
     * @param string $newFileName optional, if not given original name is used
     * @return string The new identifier
     */
    public function importFile(\TYPO3\CMS\Core\Resource\FileInterface $file, $targetFolderIdentifier, $newFileName = NULL) {        
        $newFileName = $this->sanitizeFileName($newFileName ? $newFileName : $file->getName());
        $newFileIdentifier = $this->canonicalizeAndCheckFolderIdentifier($targetFolderIdentifier) . $newFileName;
        $targetPath = $this->absoluteBasePath . $newFileIdentifier;

        $handle = fopen(self::IMPORT_SOURCE_BASE . $file->getPublicUrl(), 'r');
        if (!$handle) {
            throw new \RuntimeException('Could not open file via URL');
        }

        if (!file_put_contents($targetPath, $handle) || !file_exists($targetPath)) {
            throw new \RuntimeException('Adding file ' . $localFilePath . ' at ' . $newFileIdentifier . ' failed.');
        }

        clearstatcache();
        GeneralUtility::fixPermissions($targetPath);

        return $newFileIdentifier;
    }
}

Patch set 9 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/33955

Patch set 10 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/33955

Patch set 11 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/33955

Patch set 12 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/33955

Patch set 13 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/33955

Patch set 14 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/33955

Patch set 15 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/33955

Patch set 16 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/33955

Patch set 17 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/33955

Patch set 18 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/33955

Patch set 19 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/33955