/* Check that a string is a valid file name. We require that it be valid
* UTF-8, that it not be empty, and that it not contain embedded forward
* slashes. Also checks that the length of the string is not more than the
/* Check that a string is a valid file name. We require that it be valid
* UTF-8, that it not be empty, and that it not contain embedded forward
* slashes. Also checks that the length of the string is not more than the