DIR * xopendir(const char *filename);
DIR * xfdopendir(int fd);
struct dirent * xreaddir(DIR *dirp);
int xreaddir_r(DIR *dirp, struct dirent *entry, struct dirent **result);
long xtelldir(DIR *dirp);
void xseekdir(DIR *dirp, long loc);
void xrewinddir(DIR *dirp);
int xclosedir(DIR *dirp);
int xdirfd(DIR *dirp);