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dir(5) [v7 man page]

DIR(5)								File Formats Manual							    DIR(5)

dir - format of directories SYNOPSIS
#include <sys/dir.h> DESCRIPTION
A directory behaves exactly like an ordinary file, save that no user may write into a directory. The fact that a file is a directory is indicated by a bit in the flag word of its i-node entry see, filsys(5). The structure of a directory entry as given in the include file is: By convention, the first two entries in each directory are for `.' and `..'. The first is an entry for the directory itself. The second is for the parent directory. The meaning of `..' is modified for the root directory of the master file system and for the root directories of removable file systems. In the first case, there is no parent, and in the second, the system does not permit off-device references. Therefore in both cases `..' has the same meaning as `.'. SEE ALSO
filsys(5) DIR(5)

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DIR(5)							      BSD File Formats Manual							    DIR(5)

dir, dirent -- directory file format SYNOPSIS
#include <dirent.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 referred 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 mount(2) and mount(8).) The directory entry format is defined in the file <sys/dirent.h> (which should not be included directly by applications): #ifndef _SYS_DIRENT_H_ #define _SYS_DIRENT_H_ #include <machine/ansi.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. */ struct dirent { __uint32_t d_fileno; /* file number of entry */ __uint16_t d_reclen; /* length of this record */ __uint8_t d_type; /* file type, see below */ __uint8_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 /* * Convert between stat structure types and directory types. */ #define IFTODT(mode) (((mode) & 0170000) >> 12) #define DTTOIF(dirtype) ((dirtype) << 12) /* * The _GENERIC_DIRSIZ macro gives the minimum record length which will hold * the directory entry. This requires the amount of space in struct direct * without the d_name field, plus enough space for the name with a terminating * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary. */ #define _GENERIC_DIRSIZ(dp) ((sizeof (struct dirent) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3)) #ifdef _KERNEL #define GENERIC_DIRSIZ(dp) _GENERIC_DIRSIZ(dp) #endif #endif /* !_SYS_DIRENT_H_ */ SEE ALSO
fs(5), inode(5) HISTORY
A dir file format appeared in Version 7 AT&T UNIX. BUGS
The usage of the member d_type of struct dirent is unportable as it is FreeBSD-specific. It also may fail on certain file systems, for exam- ple the cd9660 file system. BSD
April 19, 1994 BSD
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