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Annotation of Net2/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 and use in source and binary forms, with or without
        !             6:  * modification, are permitted provided that the following conditions
        !             7:  * are met:
        !             8:  * 1. Redistributions of source code must retain the above copyright
        !             9:  *    notice, this list of conditions and the following disclaimer.
        !            10:  * 2. Redistributions in binary form must reproduce the above copyright
        !            11:  *    notice, this list of conditions and the following disclaimer in the
        !            12:  *    documentation and/or other materials provided with the distribution.
        !            13:  * 3. All advertising materials mentioning features or use of this software
        !            14:  *    must display the following acknowledgement:
        !            15:  *     This product includes software developed by the University of
        !            16:  *     California, Berkeley and its contributors.
        !            17:  * 4. Neither the name of the University nor the names of its contributors
        !            18:  *    may be used to endorse or promote products derived from this software
        !            19:  *    without specific prior written permission.
        !            20:  *
        !            21:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            22:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            23:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            24:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            25:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            26:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            27:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            28:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            29:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            30:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            31:  * SUCH DAMAGE.
        !            32:  *
        !            33:  *     @(#)dir.h       7.10 (Berkeley) 3/25/91
        !            34:  */
        !            35: 
        !            36: #ifndef _DIR_H_
        !            37: #define        _DIR_H_
        !            38: 
        !            39: /*
        !            40:  * A directory consists of some number of blocks of DIRBLKSIZ
        !            41:  * bytes, where DIRBLKSIZ is chosen such that it can be transferred
        !            42:  * to disk in a single atomic operation (e.g. 512 bytes on most machines).
        !            43:  *
        !            44:  * Each DIRBLKSIZ byte block contains some number of directory entry
        !            45:  * structures, which are of variable length.  Each directory entry has
        !            46:  * a struct direct at the front of it, containing its inode number,
        !            47:  * the length of the entry, and the length of the name contained in
        !            48:  * the entry.  These are followed by the name padded to a 4 byte boundary
        !            49:  * with null bytes.  All names are guaranteed null terminated.
        !            50:  * The maximum length of a name in a directory is MAXNAMLEN.
        !            51:  *
        !            52:  * The macro DIRSIZ(dp) gives the amount of space required to represent
        !            53:  * a directory entry.  Free space in a directory is represented by
        !            54:  * entries which have dp->d_reclen > DIRSIZ(dp).  All DIRBLKSIZ bytes
        !            55:  * in a directory block are claimed by the directory entries.  This
        !            56:  * usually results in the last entry in a directory having a large
        !            57:  * dp->d_reclen.  When entries are deleted from a directory, the
        !            58:  * space is returned to the previous entry in the same directory
        !            59:  * block by increasing its dp->d_reclen.  If the first entry of
        !            60:  * a directory block is free, then its dp->d_ino is set to 0.
        !            61:  * Entries other than the first in a directory do not normally have
        !            62:  * dp->d_ino set to 0.
        !            63:  */
        !            64: #define DIRBLKSIZ      DEV_BSIZE
        !            65: #define        MAXNAMLEN       255
        !            66: 
        !            67: struct direct {
        !            68:        u_long  d_ino;                  /* inode number of entry */
        !            69:        u_short d_reclen;               /* length of this record */
        !            70:        u_short d_namlen;               /* length of string in d_name */
        !            71:        char    d_name[MAXNAMLEN + 1];  /* name with length <= MAXNAMLEN */
        !            72: };
        !            73: 
        !            74: /*
        !            75:  * The DIRSIZ macro gives the minimum record length which will hold
        !            76:  * the directory entry.  This requires the amount of space in struct direct
        !            77:  * without the d_name field, plus enough space for the name with a terminating
        !            78:  * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary.
        !            79:  */
        !            80: #define DIRSIZ(dp) \
        !            81:     ((sizeof (struct direct) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3))
        !            82: 
        !            83: /*
        !            84:  * Template for manipulating directories.
        !            85:  * Should use struct direct's, but the name field
        !            86:  * is MAXNAMLEN - 1, and this just won't do.
        !            87:  */
        !            88: struct dirtemplate {
        !            89:        u_long  dot_ino;
        !            90:        short   dot_reclen;
        !            91:        short   dot_namlen;
        !            92:        char    dot_name[4];            /* must be multiple of 4 */
        !            93:        u_long  dotdot_ino;
        !            94:        short   dotdot_reclen;
        !            95:        short   dotdot_namlen;
        !            96:        char    dotdot_name[4];         /* ditto */
        !            97: };
        !            98: #endif /* !_DIR_H_ */

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