WP_Import::fetch_remote_file PHP Method

        function fetch_remote_file($url, $post)
        {
            // extract the file name and extension from the url
            $file_name = basename($url);
            // get placeholder file in the upload dir with a unique, sanitized filename
            $upload = wp_upload_bits($file_name, 0, '', $post['upload_date']);
            if ($upload['error']) {
                return new WP_Error('upload_dir_error', $upload['error']);
            }
            // fetch the remote url and write it to the placeholder file
            $headers = wp_get_http($url, $upload['file']);
            // request failed
            if (!$headers) {
                @unlink($upload['file']);
                return new WP_Error('import_file_error', __('Remote server did not respond', 'wordpress-importer'));
            }
            // make sure the fetch was successful
            if ($headers['response'] != '200') {
                @unlink($upload['file']);
                return new WP_Error('import_file_error', sprintf(__('Remote server returned error response %1$d %2$s', 'wordpress-importer'), esc_html($headers['response']), get_status_header_desc($headers['response'])));
            }
            $filesize = filesize($upload['file']);
            if (isset($headers['content-length']) && $filesize != $headers['content-length']) {
                @unlink($upload['file']);
                return new WP_Error('import_file_error', __('Remote file is incorrect size', 'wordpress-importer'));
            }
            if (0 == $filesize) {
                @unlink($upload['file']);
                return new WP_Error('import_file_error', __('Zero size file downloaded', 'wordpress-importer'));
            }
            $max_size = (int) $this->max_attachment_size();
            if (!empty($max_size) && $filesize > $max_size) {
                @unlink($upload['file']);
                return new WP_Error('import_file_error', sprintf(__('Remote file is too large, limit is %s', 'wordpress-importer'), size_format($max_size)));
            }
            // keep track of the old and new urls so we can substitute them later
            $this->url_remap[$url] = $upload['url'];
            $this->url_remap[$post['guid']] = $upload['url'];
            // r13735, really needed?
            // keep track of the destination if the remote url is redirected somewhere else
            if (isset($headers['x-final-location']) && $headers['x-final-location'] != $url) {
                $this->url_remap[$headers['x-final-location']] = $upload['url'];
            }
            return $upload;
        }

 /**
  * Use local images instead of remote images
  * 
  * @see WP_Import::fetch_remote_file()
  */
 public function fetch_remote_file($url, $post)
 {
     // only use if demo-data is present in the url
     if (!strstr($url, '/demo-data/')) {
         return parent::fetch_remote_file($url, $post);
     }
     // extract the file name and extension from the url
     $file_name = basename($url);
     // get placeholder file in the upload dir with a unique, sanitized filename
     $upload = wp_upload_bits($file_name, 0, '', $post['upload_date']);
     if ($upload['error']) {
         return new WP_Error('upload_dir_error', $upload['error']);
     }
     // use the local image and write it to the placeholder file
     $local_file = WP_CONTENT_DIR . '/' . substr($url, strrpos($url, '/themes/'));
     file_put_contents($upload['file'], file_get_contents($local_file));
     $filesize = filesize($upload['file']);
     if (0 == $filesize) {
         @unlink($upload['file']);
         return new WP_Error('import_file_error', __('Zero size file downloaded', 'wordpress-importer'));
     }
     $max_size = (int) $this->max_attachment_size();
     if (!empty($max_size) && $filesize > $max_size) {
         @unlink($upload['file']);
         return new WP_Error('import_file_error', sprintf(__('Remote file is too large, limit is %s', 'wordpress-importer'), size_format($max_size)));
     }
     // keep track of the old and new urls so we can substitute them later
     $this->url_remap[$url] = $upload['url'];
     $this->url_remap[$post['guid']] = $upload['url'];
     // r13735, really needed?
     return $upload;
 }