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Annotation of 43BSDReno/sys/ufs/dir.h, revision 1.1.1.1

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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