dirfd - extract file descriptor

Syntax	#include <dirent.h> int dirfd(DIR *dirp);
Description	The function dirfd() extracts the file descriptor from the DIR object to which dirp points. If an attempt is made to close or modify the file descriptor with functions other than closedir(), readdir(), readdir_r(), rewinddir() or seekdir(), the behaviour is undefined.
Return val.	File descriptor of the DIR object
		if successful.
	-1	if an error occurs. errno is set to indicate the error.
Errors	dirfd() fails, if: EINVAL      dirp does not point to an open directory stream.
See also	closedir(), readdir(), readdir_r(), rewinddir(), seekdir()