wp_import_handle_upload()

function wp_import_handle_upload() {
	if ( ! isset( $_FILES['import'] ) ) {
		return array(
			'error' => __( 'File is empty. Please upload something more substantial. This error could also be caused by uploads being disabled in your php.ini or by post_max_size being defined as smaller than upload_max_filesize in php.ini.' )
		);
	}

	$overrides = array( 'test_form' => false, 'test_type' => false );
	$_FILES['import']['name'] .= '.txt';
	$upload = wp_handle_upload( $_FILES['import'], $overrides );

	if ( isset( $upload['error'] ) ) {
		return $upload;
	}

	// Construct the object array
	$object = array(
		'post_title' => basename( $upload['file'] ),
		'post_content' => $upload['url'],
		'post_mime_type' => $upload['type'],
		'guid' => $upload['url'],
		'context' => 'import',
		'post_status' => 'private'
	);

	// Save the data
	$id = wp_insert_attachment( $object, $upload['file'] );

	/*
	 * Schedule a cleanup for one day from now in case of failed
	 * import or missing wp_import_cleanup() call.
	 */
	wp_schedule_single_event( time() + DAY_IN_SECONDS, 'importer_scheduled_cleanup', array( $id ) );

	return array( 'file' => $upload['file'], 'id' => $id );
}