The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.
A newer edition of this document exists here


dirent.h - format of directory entries


#include <dirent.h>


The internal format of directories is unspecified.

The <dirent.h> header shall define the following type:

A type representing a directory stream.

It shall also define the structure dirent which shall include the following members:

[XSI][Option Start]
ino_t  d_ino       File serial number. 
[Option End]
char   d_name[]    Name of entry. 

[XSI] [Option Start] The type ino_t shall be defined as described in <sys/types.h>. [Option End]

The character array d_name is of unspecified size, but the number of bytes preceding the terminating null byte shall not exceed {NAME_MAX}.

The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.

int            closedir(DIR *);
DIR           *opendir(const char *);
struct dirent *readdir(DIR *);
[TSF][Option Start]
int            readdir_r(DIR *restrict, struct dirent *restrict,
                   struct dirent **restrict);
[Option End]
void           rewinddir(DIR *);
[XSI][Option Start]
void           seekdir(DIR *, long);
long           telldir(DIR *);
[Option End]

The following sections are informative.




Information similar to that in the <dirent.h> header is contained in a file <sys/dir.h> in 4.2 BSD and 4.3 BSD. The equivalent in these implementations of struct dirent from this volume of IEEE Std 1003.1-2001 is struct direct. The filename was changed because the name <sys/dir.h> was also used in earlier implementations to refer to definitions related to the older access method; this produced name conflicts. The name of the structure was changed because this volume of IEEE Std 1003.1-2001 does not completely define what is in the structure, so it could be different on some implementations from struct direct.

The name of an array of char of an unspecified size should not be used as an lvalue. Use of:


is incorrect; use:



The array of char d_name is not a fixed size. Implementations may need to declare struct dirent with an array size for d_name of 1, but the actual number of characters provided matches (or only slightly exceeds) the length of the filename.




<sys/types.h>, the System Interfaces volume of IEEE Std 1003.1-2001, closedir(), opendir(), readdir(), readdir_r(), rewinddir(), seekdir(), telldir()


First released in Issue 2.

Issue 5

The DESCRIPTION is updated for alignment with the POSIX Threads Extension.

Issue 6

The Open Group Corrigendum U026/7 is applied, correcting the prototype for readdir_r().

The restrict keyword is added to the prototype for readdir_r().

End of informative text.

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