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dirfd - get directory stream file descriptor
#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)
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.
On success, a nonnegative file descriptor is returned. On error, -1 is returned, and errno is set to indicate the cause of the error.
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.
Multithreading (see pthreads(7)) The dirfd() function is thread-safe.
POSIX.1-2008. This function was a BSD extension, present in 4.3BSD-Reno, not in 4.2BSD.
The prototype for dirfd() is available only if _BSD_SOURCE or _SVID_SOURCE is defined.
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