readdir — read a directory
#include <sys/types.h> #include <dirent.h>
struct dirent *readdir( |
DIR * | dir); |
The readdir() function
returns a pointer to a dirent
structure representing the next directory entry in the
directory stream pointed to by dir. It returns NULL on
reaching the end-of-file or if an error occurred.
On Linux, the dirent structure is defined as follows:
struct dirent { ino_t d_ino;off_t d_off;unsigned short d_reclen;unsigned char d_type;char d_name[256];};
According to POSIX, the dirent structure contains a field
char d_name[] of
unspecified size, with at most NAME_MAX characters preceding the
terminating null byte. POSIX.1-2001 also documents the field
ino_t d_ino as an XSI
extension. The other fields are unstandardized, and not
present on all systems; see NOTES below for some further
details.
The data returned by readdir() may be overwritten by subsequent
calls to readdir() for the same
directory stream.
The readdir() function
returns a pointer to a dirent
structure, or NULL if an error occurs or end-of-file is
reached. On error, errno is set
appropriately.
Only the fields d_name and d_ino are specified in
POSIX.1-2001. The remaining fields are available on many, but
not all systems. Under glibc, programs can check for the
availability of the fields not defined in POSIX.1 by testing
whether the macros _DIRENT_HAVE_D_NAMLEN, _DIRENT_HAVE_D_RECLEN, _DIRENT_HAVE_D_OFF, or _DIRENT_HAVE_D_TYPE are defined.
Other than Linux, the d_type field is available
mainly only on BSD systems. This field makes it possible to
avoid the expense of calling stat(2) if further actions
depend on the type of the file. If the _BSD_SOURCE feature test macro is defined,
then glibc defines the following macro constants for the
value returned in d_type:
DT_UNKNOWNThe file type is unknown.
DT_REGThis is a regular file.
DT_DIRThis is a directory.
DT_FIFOThis is a named pipe, or FIFO.
DT_SOCKThis is a Unix domain socket.
DT_CHRThis is a character device.
DT_BLKThis is a block device.
If the file type could not be determined, the value
DT_UNKNOWN is returned in
d_type.
read(2), closedir(3), dirfd(3), ftw(3), opendir(3), rewinddir(3), scandir(3), seekdir(3), telldir(3), feature_test_macros(7)
This page is part of release 2.79 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/.
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Copyright (C) 1993 David Metcalfe (davidprism.demon.co.uk) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. References consulted: Linux libc source code Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) 386BSD man pages Modified Sat Jul 24 16:09:49 1993 by Rik Faith (faithcs.unc.edu) Modified 11 June 1995 by Andries Brouwer (aebcwi.nl) Modified 22 July 1996 by Andries Brouwer (aebcwi.nl) 2007-07-30 Ulrich Drepper <drepperredhat.com>, mtk: Rework discussion of non-standard structure fields. |