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ext2fs_dir.h revision 1.1 
      1 /*	$NetBSD: ext2fs_dir.h,v 1.1 1997/06/11 09:33:50 bouyer Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1997 Manuel Bouyer.
      5  * Copyright (c) 1982, 1986, 1989, 1993
      6  *	The Regents of the University of California.  All rights reserved.
      7  * (c) UNIX System Laboratories, Inc.
      8  * All or some portions of this file are derived from material licensed
      9  * to the University of California by American Telephone and Telegraph
     10  * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     11  * the permission of UNIX System Laboratories, Inc.
     12  *
     13  * Redistribution and use in source and binary forms, with or without
     14  * modification, are permitted provided that the following conditions
     15  * are met:
     16  * 1. Redistributions of source code must retain the above copyright
     17  *    notice, this list of conditions and the following disclaimer.
     18  * 2. Redistributions in binary form must reproduce the above copyright
     19  *    notice, this list of conditions and the following disclaimer in the
     20  *    documentation and/or other materials provided with the distribution.
     21  * 3. All advertising materials mentioning features or use of this software
     22  *    must display the following acknowledgement:
     23  *	This product includes software developed by the University of
     24  *	California, Berkeley and its contributors.
     25  * 4. Neither the name of the University nor the names of its contributors
     26  *    may be used to endorse or promote products derived from this software
     27  *    without specific prior written permission.
     28  *
     29  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     30  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     31  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     32  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     33  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     34  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     35  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     36  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     37  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     38  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     39  * SUCH DAMAGE.
     40  *
     41  *	@(#)dir.h	8.4 (Berkeley) 8/10/94
     42  * Modified for ext2fs by Manuel Bouyer.
     43  */
     44 
     45 #ifndef _EXT2FS_DIR_H_
     46 #define	_EXT2FS_DIR_H_
     47 
     48 /*
     49  * Theoretically, directories can be more than 2Gb in length, however, in
     50  * practice this seems unlikely. So, we define the type doff_t as a 32-bit
     51  * quantity to keep down the cost of doing lookup on a 32-bit machine.
     52 */
     53 #define	doff_t		int32_t
     54 #define	EXT2FS_MAXDIRSIZE	(0x7fffffff)
     55 
     56 /*
     57  * A directory consists of some number of blocks of e2fs_bsize bytes.
     58  *
     59  * Each block contains some number of directory entry
     60  * structures, which are of variable length.  Each directory entry has
     61  * a struct direct at the front of it, containing its inode number,
     62  * the length of the entry, and the length of the name contained in
     63  * the entry.  These are followed by the name padded to a 4 byte boundary
     64  * with null bytes.  All names are guaranteed null terminated.
     65  * The maximum length of a name in a directory is EXT2FS_MAXNAMLEN.
     66  *
     67  * The macro EXT2FS_DIRSIZ(fmt, dp) gives the amount of space required to
     68  * represent a directory entry.  Free space in a directory is represented by
     69  * entries which have dp->e2d_reclen > DIRSIZ(fmt, dp).  All d2fs_bsize bytes
     70  * in a directory block are claimed by the directory entries.  This
     71  * usually results in the last entry in a directory having a large
     72  * dp->e2d_reclen.  When entries are deleted from a directory, the
     73  * space is returned to the previous entry in the same directory
     74  * block by increasing its dp->e2d_reclen.  If the first entry of
     75  * a directory block is free, then its dp->e2d_ino is set to 0.
     76  * Entries other than the first in a directory do not normally have
     77  * dp->e2d_ino set to 0.
     78  */
     79 
     80 #define	EXT2FS_MAXNAMLEN	255
     81 
     82 struct	ext2fs_direct {
     83 	u_int32_t e2d_ino;		/* inode number of entry */
     84 	u_int16_t e2d_reclen;		/* length of this record */
     85 	u_int16_t e2d_namlen;		/* length of string in d_name */
     86 	char	  e2d_name[EXT2FS_MAXNAMLEN];/* name with length <= EXT2FS_MAXNAMLEN */
     87 };
     88 
     89 /*
     90  * The EXT2FS_DIRSIZ macro gives the minimum record length which will hold
     91  * the directory entryfor a name len "len" (without the terminating null byte).
     92  * This requires the amount of space in struct direct
     93  * without the d_name field, plus enough space for the name without a
     94  * terminating null byte, rounded up to a 4 byte boundary.
     95  */
     96 #define EXT2FS_DIRSIZ(len) \
     97    (( 8 + len + 3) &~ 3)
     98 
     99 /*
    100  * Template for manipulating directories.  Should use struct direct's,
    101  * but the name field is EXT2FS_MAXNAMLEN - 1, and this just won't do.
    102  */
    103 struct ext2fs_dirtemplate {
    104 	u_int32_t	dot_ino;
    105 	int16_t		dot_reclen;
    106 	u_int16_t	dot_namlen;
    107 	char		dot_name[4];	/* must be multiple of 4 */
    108 	u_int32_t	dotdot_ino;
    109 	int16_t		dotdot_reclen;
    110 	u_int16_t	dotdot_namlen;
    111 	char		dotdot_name[4];	/* ditto */
    112 };
    113 
    114 #endif /* !_EXT2FS_DIR_H_ */
    115