DIR(5) MachTen Programmer’s Manual DIR(5)

NAME
dir, dirent - directory file format

SYNOPSIS
#include <sys/types.h>
#include <sys/dir.h>

DESCRIPTION
Directories provide a convenient hierarchical method of grouping files
while obscuring the underlying details of the storage medium. A directo-
ry file is differentiated from a plain file by a flag in its inode(5) en-
try. It consists of records (directory entries) each of which contains
information about a file and a pointer to the file itself. Directory en-
tries may contain other directories as well as plain files; such nested
directories are refered to as subdirectories. A hierarchy of directories
and files is formed in this manner and is called a file system (or re-
ferred to as a file system tree).

Each directory file contains two special directory entries; one is a
pointer to the directory itself called dot ‘.’ and the other a pointer to
its parent directory called dot-dot ‘..’. Dot and dot-dot are valid path-
names, however, the system root directory ‘/’, has no parent and dot-dot
points to itself like dot.

File system nodes are ordinary directory files on which has been grafted
a file system object, such as a physical disk or a partitioned area of
such a disk. (See mount(1) and mount(8).)

The directory entry format is defined in the file <dirent.h>:

#ifndef _DIRENT_H_
#define _DIRENT_H_

/*
* A directory entry has a struct dirent at the front of it, containing its
* inode number, the length of the entry, and the length of the name
* contained in the entry. These are followed by the name padded to a 4
* byte boundary with null bytes. All names are guaranteed null terminated.
* The maximum length of a name in a directory is MAXNAMLEN.
*/

struct dirent {
u_long d_fileno; /* file number of entry */
u_short d_reclen; /* length of this record */
u_short d_namlen; /* length of string in d_name */
#ifdef _POSIX_SOURCE
char d_name[MAXNAMLEN + 1]; /* maximum name length */
#else
#define MAXNAMLEN 255
char d_name[MAXNAMLEN + 1]; /* maximum name length */
#endif

};

#ifdef _POSIX_SOURCE
typedef void * DIR;
#else

#define d_ino d_fileno /* backward compatibility */

/* definitions for library routines operating on directories. */
#define DIRBLKSIZ 1024

/* structure describing an open directory. */
typedef struct _dirdesc {
int dd_fd; /* file descriptor associated with directory */
long dd_loc; /* offset in current buffer */
long dd_size; /* amount of data returned by getdirentries */
char *dd_buf; /* data buffer */
int dd_len; /* size of data buffer */
long dd_seek; /* magic cookie returned by getdirentries */
} DIR;

#define dirfd(dirp) ((dirp)->dd_fd)

#ifndef NULL
#define NULL 0
#endif

#endif /* _POSIX_SOURCE */

#ifndef KERNEL

#include <sys/cdefs.h>

#endif /* !KERNEL */

#endif /* !_DIRENT_H_ */