WordPress at a glance
function is not described

validate_file_to_edit() WP 1.5.0

Makes sure that the file that was requested to be edited is allowed to be edited.

Function will die if you are not allowed to edit the file.

No Hooks.

Return

String/null.

Usage

validate_file_to_edit( $file, $allowed_files );
$file(string) (required)
File the user is attempting to edit.
$allowed_files(array)
Array of allowed files to edit, $file must match an entry exactly.
Default: array()

Code of validate file to edit: wp-admin/includes/file.php VER 5.0.3

<?php
function validate_file_to_edit( $file, $allowed_files = array() ) {
	$code = validate_file( $file, $allowed_files );

	if (!$code )
		return $file;

	switch ( $code ) {
		case 1 :
			wp_die( __( 'Sorry, that file cannot be edited.' ) );

		// case 2 :
		// wp_die( __('Sorry, can&#8217;t call files with their real path.' ));

		case 3 :
			wp_die( __( 'Sorry, that file cannot be edited.' ) );
	}
}