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Annotation of Net2/ufs/dir.h, revision 1.1.1.2

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:  *
1.1.1.2 ! root       33:  *     from: @(#)dir.h 7.10 (Berkeley) 3/25/91
        !            34:  *     dir.h,v 1.3 1993/05/20 03:53:21 cgd Exp
1.1       root       35:  */
                     36: 
1.1.1.2 ! root       37: #ifndef _UFS_DIR_H_
        !            38: #define _UFS_DIR_H_
1.1       root       39: 
                     40: /*
                     41:  * A directory consists of some number of blocks of DIRBLKSIZ
                     42:  * bytes, where DIRBLKSIZ is chosen such that it can be transferred
                     43:  * to disk in a single atomic operation (e.g. 512 bytes on most machines).
                     44:  *
                     45:  * Each DIRBLKSIZ byte block contains some number of directory entry
                     46:  * structures, which are of variable length.  Each directory entry has
                     47:  * a struct direct at the front of it, containing its inode number,
                     48:  * the length of the entry, and the length of the name contained in
                     49:  * the entry.  These are followed by the name padded to a 4 byte boundary
                     50:  * with null bytes.  All names are guaranteed null terminated.
                     51:  * The maximum length of a name in a directory is MAXNAMLEN.
                     52:  *
                     53:  * The macro DIRSIZ(dp) gives the amount of space required to represent
                     54:  * a directory entry.  Free space in a directory is represented by
                     55:  * entries which have dp->d_reclen > DIRSIZ(dp).  All DIRBLKSIZ bytes
                     56:  * in a directory block are claimed by the directory entries.  This
                     57:  * usually results in the last entry in a directory having a large
                     58:  * dp->d_reclen.  When entries are deleted from a directory, the
                     59:  * space is returned to the previous entry in the same directory
                     60:  * block by increasing its dp->d_reclen.  If the first entry of
                     61:  * a directory block is free, then its dp->d_ino is set to 0.
                     62:  * Entries other than the first in a directory do not normally have
                     63:  * dp->d_ino set to 0.
                     64:  */
                     65: #define DIRBLKSIZ      DEV_BSIZE
                     66: #define        MAXNAMLEN       255
                     67: 
                     68: struct direct {
                     69:        u_long  d_ino;                  /* inode number of entry */
                     70:        u_short d_reclen;               /* length of this record */
                     71:        u_short d_namlen;               /* length of string in d_name */
                     72:        char    d_name[MAXNAMLEN + 1];  /* name with length <= MAXNAMLEN */
                     73: };
                     74: 
                     75: /*
                     76:  * The DIRSIZ macro gives the minimum record length which will hold
                     77:  * the directory entry.  This requires the amount of space in struct direct
                     78:  * without the d_name field, plus enough space for the name with a terminating
                     79:  * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary.
                     80:  */
                     81: #define DIRSIZ(dp) \
                     82:     ((sizeof (struct direct) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1 + 3) &~ 3))
                     83: 
                     84: /*
                     85:  * Template for manipulating directories.
                     86:  * Should use struct direct's, but the name field
                     87:  * is MAXNAMLEN - 1, and this just won't do.
                     88:  */
                     89: struct dirtemplate {
                     90:        u_long  dot_ino;
                     91:        short   dot_reclen;
                     92:        short   dot_namlen;
                     93:        char    dot_name[4];            /* must be multiple of 4 */
                     94:        u_long  dotdot_ino;
                     95:        short   dotdot_reclen;
                     96:        short   dotdot_namlen;
                     97:        char    dotdot_name[4];         /* ditto */
                     98: };
1.1.1.2 ! root       99: 
        !           100: #endif /* !_UFS_DIR_H_ */

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