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34 * @(#)dir.h 8.2 (Berkeley) 1/21/94
38 #ifndef _UFS_UFS_DIR_H_
39 #define _UFS_UFS_DIR_H_
42 * Theoretically, directories can be more than 2Gb in length, however, in
43 * practice this seems unlikely. So, we define the type doff_t as a 32-bit
44 * quantity to keep down the cost of doing lookup on a 32-bit machine.
46 #define doff_t int32_t
47 #define MAXDIRSIZE (0x7fffffff)
50 * A directory consists of some number of blocks of DIRBLKSIZ
51 * bytes, where DIRBLKSIZ is chosen such that it can be transferred
52 * to disk in a single atomic operation (e.g. 512 bytes on most machines).
54 * Each DIRBLKSIZ byte block contains some number of directory entry
55 * structures, which are of variable length. Each directory entry has
56 * a struct direct at the front of it, containing its inode number,
57 * the length of the entry, and the length of the name contained in
58 * the entry. These are followed by the name padded to a 4 byte boundary
59 * with null bytes. All names are guaranteed null terminated.
60 * The maximum length of a name in a directory is MAXNAMLEN.
62 * The macro DIRSIZ(fmt, dp) gives the amount of space required to represent
63 * a directory entry. Free space in a directory is represented by
64 * entries which have dp->d_reclen > DIRSIZ(fmt, dp). All DIRBLKSIZ bytes
65 * in a directory block are claimed by the directory entries. This
66 * usually results in the last entry in a directory having a large
67 * dp->d_reclen. When entries are deleted from a directory, the
68 * space is returned to the previous entry in the same directory
69 * block by increasing its dp->d_reclen. If the first entry of
70 * a directory block is free, then its dp->d_ino is set to 0.
71 * Entries other than the first in a directory do not normally have
74 #define DIRBLKSIZ DEV_BSIZE
78 u_int32_t d_ino; /* inode number of entry */
79 u_int16_t d_reclen; /* length of this record */
80 u_int8_t d_type; /* file type, see below */
81 u_int8_t d_namlen; /* length of string in d_name */
82 char d_name[MAXNAMLEN + 1];/* name with length <= MAXNAMLEN */
99 * Convert between stat structure types and directory types.
101 #define IFTODT(mode) (((mode) & 0170000) >> 12)
102 #define DTTOIF(dirtype) ((dirtype) << 12)
105 * The DIRSIZ macro gives the minimum record length which will hold
106 * the directory entry. This requires the amount of space in struct direct
107 * without the d_name field, plus enough space for the name with a terminating
108 * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary.
112 #define DIRECTSIZ(namlen) \
113 (((uintptr_t)&((struct direct *)0)->d_name + \
114 ((namlen)+1)*sizeof(((struct direct *)0)->d_name[0]) + 3) & ~3)
115 #if (BYTE_ORDER == LITTLE_ENDIAN)
116 #define DIRSIZ(oldfmt, dp) \
117 ((oldfmt) ? DIRECTSIZ((dp)->d_type) : DIRECTSIZ((dp)->d_namlen))
119 #define DIRSIZ(oldfmt, dp) \
120 DIRECTSIZ((dp)->d_namlen)
126 * Template for manipulating directories. Should use struct direct's,
127 * but the name field is MAXNAMLEN - 1, and this just won't do.
134 char dot_name[4]; /* must be multiple of 4 */
135 u_int32_t dotdot_ino;
136 int16_t dotdot_reclen;
137 u_int8_t dotdot_type;
138 u_int8_t dotdot_namlen;
139 char dotdot_name[4]; /* ditto */
143 * This is the old format of directories, sanz type element.
145 struct odirtemplate {
148 u_int16_t dot_namlen;
149 char dot_name[4]; /* must be multiple of 4 */
150 u_int32_t dotdot_ino;
151 int16_t dotdot_reclen;
152 u_int16_t dotdot_namlen;
153 char dotdot_name[4]; /* ditto */
155 #endif /* !_DIR_H_ */