DIRFD(3) Linux Programmers Manual DIRFD(3)
dirfd - get directory stream file descriptor
int dirfd(DIR *dir);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
dirfd(): _BSD_SOURCE || _SVID_SOURCE
The function dirfd() returns the file descriptor associated with the
directory stream dir.
This descriptor is the one used internally by the directory stream. As
a result, it is only useful for functions which do not depend on or
alter the file position, such as fstat(2) and fchdir(2). It will be
automatically closed when closedir(3) is called.
On success, a non-negative file descriptor is returned. On error, -1
The upcoming POSIX.1 revision specifies two errors, neither of which is
returned by the current implementation.
EINVAL dirp does not refer to a valid directory stream.
The implementation does not support the association of a file
descriptor with a directory.
This is a BSD extension, present in 4.3BSD-Reno, not in 4.2BSD. It is
present in libc5 (since 5.1.2) and in glibc2. This function is under
consideration for inclusion in a future version of POSIX.1.
The prototype for dirfd() is only available if _BSD_SOURCE or
_SVID_SOURCE is defined.
open(2), closedir(3), opendir(3), readdir(3), rewinddir(3), scandir(3),
This page is part of release 3.05 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2008-07-02 DIRFD(3)