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Annotation of 43BSDReno/sys/ufs/dir.h, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1982, 1986, 1989 The Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution is only permitted until one year after the first shipment
        !             6:  * of 4.4BSD by the Regents.  Otherwise, redistribution and use in source and
        !             7:  * binary forms are permitted provided that: (1) source distributions retain
        !             8:  * this entire copyright notice and comment, and (2) distributions including
        !             9:  * binaries display the following acknowledgement:  This product includes
        !            10:  * software developed by the University of California, Berkeley and its
        !            11:  * contributors'' in the documentation or other materials provided with the
        !            12:  * distribution and in all advertising materials mentioning features or use
        !            13:  * of this software.  Neither the name of the University nor the names of
        !            14:  * its contributors may be used to endorse or promote products derived from
        !            15:  * this software without specific prior written permission.
        !            16:  * THIS SOFTWARE IS PROVIDED AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
        !            17:  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
        !            18:  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            19:  *
        !            20:  *     @(#)dir.h       7.9 (Berkeley) 6/28/90
        !            21:  */
        !            22: 
        !            23: #ifndef _DIR_
        !            24: #define        _DIR_
        !            25: 
        !            26: /*
        !            27:  * A directory consists of some number of blocks of DIRBLKSIZ
        !            28:  * bytes, where DIRBLKSIZ is chosen such that it can be transferred
        !            29:  * to disk in a single atomic operation (e.g. 512 bytes on most machines).
        !            30:  *
        !            31:  * Each DIRBLKSIZ byte block contains some number of directory entry
        !            32:  * structures, which are of variable length.  Each directory entry has
        !            33:  * a struct direct at the front of it, containing its inode number,
        !            34:  * the length of the entry, and the length of the name contained in
        !            35:  * the entry.  These are followed by the name padded to a 4 byte boundary
        !            36:  * with null bytes.  All names are guaranteed null terminated.
        !            37:  * The maximum length of a name in a directory is MAXNAMLEN.
        !            38:  *
        !            39:  * The macro DIRSIZ(dp) gives the amount of space required to represent
        !            40:  * a directory entry.  Free space in a directory is represented by
        !            41:  * entries which have dp->d_reclen > DIRSIZ(dp).  All DIRBLKSIZ bytes
        !            42:  * in a directory block are claimed by the directory entries.  This
        !            43:  * usually results in the last entry in a directory having a large
        !            44:  * dp->d_reclen.  When entries are deleted from a directory, the
        !            45:  * space is returned to the previous entry in the same directory
        !            46:  * block by increasing its dp->d_reclen.  If the first entry of
        !            47:  * a directory block is free, then its dp->d_ino is set to 0.
        !            48:  * Entries other than the first in a directory do not normally have
        !            49:  * dp->d_ino set to 0.
        !            50:  */
        !            51: #define DIRBLKSIZ      DEV_BSIZE
        !            52: #define        MAXNAMLEN       255
        !            53: 
        !            54: struct direct {
        !            55:        u_long  d_ino;                  /* inode number of entry */
        !            56:        u_short d_reclen;               /* length of this record */
        !            57:        u_short d_namlen;               /* length of string in d_name */
        !            58:        char    d_name[MAXNAMLEN + 1];  /* name with length <= MAXNAMLEN */
        !            59: };
        !            60: 
        !            61: /*
        !            62:  * The DIRSIZ macro gives the minimum record length which will hold
        !            63:  * the directory entry.  This requires the amount of space in struct direct
        !            64:  * without the d_name field, plus enough space for the name with a terminating
        !            65:  * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary.
        !            66:  */
        !            67: #define DIRSIZ(dp) \
        !            68:     ((sizeof (struct direct) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3))
        !            69: 
        !            70: /*
        !            71:  * Template for manipulating directories.
        !            72:  * Should use struct direct's, but the name field
        !            73:  * is MAXNAMLEN - 1, and this just won't do.
        !            74:  */
        !            75: struct dirtemplate {
        !            76:        u_long  dot_ino;
        !            77:        short   dot_reclen;
        !            78:        short   dot_namlen;
        !            79:        char    dot_name[4];            /* must be multiple of 4 */
        !            80:        u_long  dotdot_ino;
        !            81:        short   dotdot_reclen;
        !            82:        short   dotdot_namlen;
        !            83:        char    dotdot_name[4];         /* ditto */
        !            84: };
        !            85: #endif /* _DIR_ */

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