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Name

dirfd - get directory stream file descriptor

Synopsis

#include <sys/types.h>
#include <dirent.h>

int dirfd(DIR *dirp);

Feature Test Macro Requirements for glibc (see feature_test_macros(7) ):

dirfd():

_BSD_SOURCE || _SVID_SOURCE
|| /* Since glibc 2.10: */
(_POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700)

Description

The function dirfd() returns the file descriptor associated with the directory stream dirp.

This descriptor is the one used internally by the directory stream. As a result, it is useful only 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.

Return Value

On success, a nonnegative file descriptor is returned. On error, -1 is returned, and errno is set to indicate the cause of the error.

Errors

POSIX.1-2008 specifies two errors, neither of which is returned by the current implementation.
EINVAL
dirp does not refer to a valid directory stream.
ENOTSUP
The implementation does not support the association of a file descriptor with a directory.

Attributes

Multithreading (see pthreads(7) )

The dirfd() function is thread-safe.

Conforming to

POSIX.1-2008. This function was a BSD extension, present in 4.3BSD-Reno, not in 4.2BSD.

Notes

The prototype for dirfd() is available only if _BSD_SOURCE or _SVID_SOURCE is defined.

See Also

open(2) , closedir(3) , opendir(3) , readdir(3) , rewinddir(3) , scandir(3) , seekdir(3) , telldir(3)

Colophon

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