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NAME

SYNOPSIS

DESCRIPTION

Directories provide a convenient hierarchical method of grouping files while obscuring the underlying details of the storage medium. A directory file is differentiated from a plain file by a flag in its entry. It consists of records (directory entries) each of which contains information about a file and a pointer to the file itself. Directory entries 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 referred 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 pathnames, 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 and The directory entry format is defined in the file #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_ */

SEE ALSO

HISTORY

A file format appeared in

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