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34 * @(#)dir.h 8.2 (Berkeley) 1/21/94
35 * $FreeBSD: src/sys/ufs/ufs/dir.h,v 1.9 1999/08/28 00:52:27 peter Exp $
38 #ifndef _VFS_GNU_EXT2FS_DIR_H_
39 #define _VFS_GNU_EXT2FS_DIR_H_
44 * Theoretically, directories can be more than 2Gb in length, however, in
45 * practice this seems unlikely. So, we define the type doff_t as a 32-bit
46 * quantity to keep down the cost of doing lookup on a 32-bit machine.
48 #define doff_t int32_t
49 #define MAXDIRSIZE (0x7fffffff)
52 * A directory consists of some number of blocks of DIRBLKSIZ
53 * bytes, where DIRBLKSIZ is chosen such that it can be transferred
54 * to disk in a single atomic operation (e.g. 512 bytes on most machines).
56 * Each DIRBLKSIZ byte block contains some number of directory entry
57 * structures, which are of variable length. Each directory entry has
58 * a struct direct at the front of it, containing its inode number,
59 * the length of the entry, and the length of the name contained in
60 * the entry. These are followed by the name padded to a 4 byte boundary
61 * with null bytes. All names are guaranteed null terminated.
62 * The maximum length of a name in a directory is MAXNAMLEN.
64 * The macro DIRSIZ(fmt, dp) gives the amount of space required to represent
65 * a directory entry. Free space in a directory is represented by
66 * entries which have dp->d_reclen > DIRSIZ(fmt, dp). All DIRBLKSIZ bytes
67 * in a directory block are claimed by the directory entries. This
68 * usually results in the last entry in a directory having a large
69 * dp->d_reclen. When entries are deleted from a directory, the
70 * space is returned to the previous entry in the same directory
71 * block by increasing its dp->d_reclen. If the first entry of
72 * a directory block is free, then its dp->d_ino is set to 0.
73 * Entries other than the first in a directory do not normally have
76 #define DIRBLKSIZ DEV_BSIZE
77 #define MAXNAMLEN EXT2_NAME_LEN
80 uint32_t d_ino; /* inode number of entry */
81 uint16_t d_reclen; /* length of this record */
82 uint8_t d_type; /* file type, see below */
83 uint8_t d_namlen; /* length of string in d_name */
84 char d_name[MAXNAMLEN + 1];/* name with length <= MAXNAMLEN */
101 * Convert between stat structure types and directory types.
103 #define IFTODT(mode) (((mode) & 0170000) >> 12)
104 #define DTTOIF(dirtype) ((dirtype) << 12)
107 * The DIRSIZ macro gives the minimum record length which will hold
108 * the directory entry. This requires the amount of space in struct direct
109 * without the d_name field, plus enough space for the name with a terminating
110 * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary.
114 #define DIRECTSIZ(namlen) \
115 ((__offsetof(struct direct, d_name) + \
116 ((namlen)+1)*sizeof(((struct direct *)0)->d_name[0]) + 3) & ~3)
117 #if (BYTE_ORDER == LITTLE_ENDIAN)
118 #define DIRSIZ(oldfmt, dp) \
119 ((oldfmt) ? DIRECTSIZ((dp)->d_type) : DIRECTSIZ((dp)->d_namlen))
121 #define DIRSIZ(oldfmt, dp) \
122 DIRECTSIZ((dp)->d_namlen)
128 * Template for manipulating directories. Should use struct direct's,
129 * but the name field is MAXNAMLEN - 1, and this just won't do.
136 char dot_name[4]; /* must be multiple of 4 */
138 int16_t dotdot_reclen;
140 uint8_t dotdot_namlen;
141 char dotdot_name[4]; /* ditto */
145 * This is the old format of directories, sanz type element.
147 struct odirtemplate {
151 char dot_name[4]; /* must be multiple of 4 */
153 int16_t dotdot_reclen;
154 uint16_t dotdot_namlen;
155 char dotdot_name[4]; /* ditto */
157 #endif /* _VFS_GNU_EXT2FS_DIR_H_ */