NAME

dirent.h - format of directory entries

SYNOPSIS

#include <dirent.h>

DESCRIPTION

The internal format of directories is unspecified.

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

DIR

A type representing a directory stream.

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

[XSI]
ino_t  d_ino       File serial number. 

char   d_name[]    Name of entry. 

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

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]
int            readdir_r(DIR *restrict, struct dirent *restrict,
                   struct dirent **restrict);

void           rewinddir(DIR *);
[XSI]
void           seekdir(DIR *, long);
long           telldir(DIR *);

APPLICATION USAGE

None.

RATIONALE

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:

sizeof(d_name)

is incorrect; use:

strlen(d_name)

instead.

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.

FUTURE DIRECTIONS

None.

SEE ALSO

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

CHANGE HISTORY

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().