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OpenDarwin 7.2.1 - man page for dirent (opendarwin section 5)

DIR(5)					       BSD File Formats 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 directory file is differentiated from a plain file by a flag in its inode(5) 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 physi- cal disk or a partitioned area of such a disk. (See mount(1) and mount(8).) The directory entry format is defined in the file <sys/dirent.h> and further in the file <dirent.h>: /*** Excerpt from <sys/dirent.h> ***/ /* * The dirent structure defines the format of directory entries returned by * the getdirentries(2) system call. * * 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. * The dirent structure defines the format of directory entries returned by * the getdirentries(2) system call. */ #ifndef _SYS_DIRENT_H #define _SYS_DIRENT_H struct dirent { u_int32_t d_fileno; /* file number of entry */ u_int16_t d_reclen; /* length of this record */ u_int8_t d_type; /* file type, see below */ u_int8_t d_namlen; /* length of string in d_name */ #ifdef _POSIX_SOURCE char d_name[255 + 1]; /* name must be no longer than this */ #else #define MAXNAMLEN 255 char d_name[MAXNAMLEN + 1]; /* name must be no longer than this */ #endif }; /* * File types */ #define DT_UNKNOWN 0 #define DT_FIFO 1 #define DT_CHR 2 #define DT_DIR 4 #define DT_BLK 6 #define DT_REG 8 #define DT_LNK 10 #define DT_SOCK 12 #define DT_WHT 14 #endif /* !_SYS_DIRENT_H_ */ ----------------------------------------- /*** Excerpt from <dirent.h> ***/ #ifndef _DIRENT_H #define _DIRENT_H #ifdef _POSIX_SOURCE typedef void * DIR; #else #define d_ino d_fileno /* backward compatibility */ /* definitions for library routines operating on directories. */ #define DIRBLKSIZ 1024 struct _telldir; /* see telldir.h */ /* 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 */ long dd_rewind; /* magic cookie for rewinding */ int dd_flags; /* flags for readdir */ pthread_mutex_t dd_lock; /* for thread locking */ struct _telldir *dd_td; /* telldir position recording */ } DIR; #define dirfd(dirp) ((dirp)->dd_fd) /* flags for opendir2 */ #define DTF_HIDEW 0x0001 /* hide whiteout entries */ #define DTF_NODUP 0x0002 /* don't return duplicate names */ /* 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 */ long dd_rewind; /* magic cookie for rewinding */ int dd_flags; /* flags for readdir */ pthread_mutex_t dd_lock; /* for thread locking */ struct _telldir *dd_td; /* telldir position recording */ } DIR; #define dirfd(dirp) ((dirp)->dd_fd) /* flags for opendir2 */ #define DTF_HIDEW 0x0001 /* hide whiteout entries */ #define DTF_NODUP 0x0002 /* don't return duplicate names */ #define DTF_REWIND 0x0004 /* rewind after reading union stack */ #define __DTF_READALL 0x0008 /* everything has been read */ #ifndef NULL #define NULL 0 #endif #endif /* _POSIX_SOURCE */ #endif /* !_DIRENT_H_ */
SEE ALSO
fs(5), inode(5)
HISTORY
A dir file format appeared in Version 7 AT&T UNIX. 4.2 Berkeley Distribution April 19, 1994 4.2 Berkeley Distribution


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