.\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
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.\" preserved on all copies.
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.\" manual under the conditions for verbatim copying, provided that the
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.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Sat Jul 24 18:46:01 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified 11 June 1995 by Andries Brouwer (aeb@cwi.nl)
.\" 2007-07-30 Ulrich Drepper <drepper@redhat.com>: document fdopendir().
.TH OPENDIR 3  2021-03-22 "GNU" "Linux Programmer's Manual"
.SH NAME
opendir, fdopendir \- open a directory
.SH SYNOPSIS
.nf
.B #include <sys/types.h>
.B #include <dirent.h>
.PP
.BI "DIR *opendir(const char *" name );
.BI "DIR *fdopendir(int " fd );
.fi
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR fdopendir ():
.nf
    Since glibc 2.10:
        _POSIX_C_SOURCE >= 200809L
    Before glibc 2.10:
        _GNU_SOURCE
.fi
.SH DESCRIPTION
The
.BR opendir ()
function opens a directory stream corresponding to the
directory \fIname\fP, and returns a pointer to the directory stream.
The stream is positioned at the first entry in the directory.
.PP
The
.BR fdopendir ()
function
is like
.BR opendir (),
but returns a directory stream for the directory referred
to by the open file descriptor
.IR fd .
After a successful call to
.BR fdopendir (),
.I fd
is used internally by the implementation,
and should not otherwise be used by the application.
.SH RETURN VALUE
The
.BR opendir ()
and
.BR fdopendir ()
functions return a pointer to the directory stream.
On error, NULL is returned, and
.I errno
is set to indicate the error.
.SH ERRORS
.TP
.B EACCES
Permission denied.
.TP
.B EBADF
.I fd
is not a valid file descriptor opened for reading.
.TP
.B EMFILE
The per-process limit on the number of open file descriptors has been reached.
.TP
.B ENFILE
The system-wide limit on the total number of open files has been reached.
.TP
.B ENOENT
Directory does not exist, or \fIname\fP is an empty string.
.TP
.B ENOMEM
Insufficient memory to complete the operation.
.TP
.B ENOTDIR
\fIname\fP is not a directory.
.SH VERSIONS
.BR fdopendir ()
is available in glibc since version 2.4.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.ad l
.nh
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.BR opendir (),
.BR fdopendir ()
T}	Thread safety	MT-Safe
.TE
.hy
.ad
.sp 1
.SH CONFORMING TO
.BR opendir ()
is present on SVr4, 4.3BSD, and specified in POSIX.1-2001.
.BR fdopendir ()
is specified in POSIX.1-2008.
.SH NOTES
Filename entries can be read from a directory stream using
.BR readdir (3).
.PP
The underlying file descriptor of the directory stream can be obtained using
.BR dirfd (3).
.PP
The
.BR opendir ()
function sets the close-on-exec flag for the file descriptor underlying the
.IR "DIR *" .
The
.BR fdopendir ()
function leaves the setting of the close-on-exec
flag unchanged for the file descriptor,
.IR fd .
POSIX.1-200x leaves it unspecified whether a successful call to
.BR fdopendir ()
will set the close-on-exec flag for the file descriptor,
.IR fd .
.SH SEE ALSO
.BR open (2),
.BR closedir (3),
.BR dirfd (3),
.BR readdir (3),
.BR rewinddir (3),
.BR scandir (3),
.BR seekdir (3),
.BR telldir (3)