TYPO3 Core

In the local driver there is

TYPO3\CMS\Core\Resource\Driver\LocalDriver::copyFileToTemporaryPath
which uses
AbstractDriver::getTemporaryPathForFile

and there you find

return \TYPO3\CMS\Core\Utility\GeneralUtility::tempnam('fal-tempfile-', '.' . PathUtility::pathinfo($fileIdentifier, PATHINFO_EXTENSION));

/**
     * Create temporary filename (Create file with unique file name)
     * This function should be used for getting temporary file names - will make your applications safe for open_basedir = on
     * REMEMBER to delete the temporary files after use! This is done by \TYPO3\CMS\Core\Utility\GeneralUtility::unlink_tempfile()
     *
     * @param string $filePrefix Prefix for temporary file
     * @param string $fileSuffix Suffix for temporary file, for example a special file extension
     * @return string result from PHP function tempnam() with PATH_site . 'typo3temp/' set for temp path.
     * @see unlink_tempfile(), upload_to_tempfile()
     */
    static public function tempnam($filePrefix, $fileSuffix = '') {

There is another occurence. Here the copy is created without any reason I can understand:

ContentObjectRenderer->getFileDataKey($key) {
...
                case 'localPath':
                    return $fileObject->getForLocalProcessing();
                    break;
...
}

Try setting up a Filelist CE and try to see the "local" path:

tt_content.uploads.20.renderObj.20.data = file:current:localPath


What you get is a list of paths of newly created files.

The code in ContentObjectRenderer must be changed like this:

$fileObject->getForLocalProcessing(FALSE);


See FileInterface why FALSE is necessary here:

/**
 * Returns a path to a local version of this file to process it locally (e.g. with some system tool).
 * If the file is normally located on a remote storages, this creates a local copy.
 * If the file is already on the local system, this only makes a new copy if $writable is set to TRUE.
 *
 * @param bool $writable Set this to FALSE if you only want to do read operations on the file.
 * @return string
 */
public function getForLocalProcessing($writable = TRUE);