/*
** Return true if the filename given is a valid filename for
** a file in a repository.  Valid filenames follow all of the
** following rules:
**
**     *  Does not begin with "/"
**     *  Does not contain any path element named "." or ".."
**     *  Does not contain any of these characters in the path: "\*[]?"
**     *  Does not end with "/".
**     *  Does not contain two or more "/" characters in a row.
**     *  Contains at least one character
*/
int file_is_simple_pathname(const char *z){
  int i;
  char c = z[0];