    public void view(@RequestParam String filename,
                     @RequestParam(required = false) String base,
                     @RequestParam(required = false) Integer tailLines,
                     HttpServletResponse response) throws IOException {
        securityCheck(filename);
        response.setContentType(MediaType.TEXT_PLAIN_VALUE);

        Path path = loggingPath(base);
        FileProvider fileProvider = getFileProvider(path);
        if (tailLines != null) {
            fileProvider.tailContent(path, filename, response.getOutputStream(), tailLines);
        }
        else {
            fileProvider.streamContent(path, filename, response.getOutputStream());
        }
    }
The software uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the software does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.