xref: /illumos-gate/usr/src/uts/common/sys/fs/ufs_fsdir.h (revision 79397983)

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 1998 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved	*/

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

#ifndef	_SYS_FS_UFS_FSDIR_H
#define	_SYS_FS_UFS_FSDIR_H

#ifdef	__cplusplus
extern "C" {
#endif

/*
 * A directory consists of some number of blocks of DIRBLKSIZ
 * bytes, where DIRBLKSIZ is chosen such that it can be transferred
 * to disk in a single atomic operation (e.g. 512 bytes on most machines).
 *
 * Each DIRBLKSIZ byte block contains some number of directory entry
 * structures, which are of variable length.  Each directory entry has
 * a struct direct at the front of it, containing its inode number,
 * the length of the entry, and the length of the name contained in
 * the entry.  These are followed by the name padded to a 4 byte boundary
 * with null bytes.  All names are guaranteed null terminated.
 * The maximum length of a name in a directory is MAXNAMLEN.
 *
 * The macro DIRSIZ(dp) gives the amount of space required to represent
 * a directory entry.  Free space in a directory is represented by
 * entries which have dp->d_reclen > DIRSIZ(dp).  All DIRBLKSIZ bytes
 * in a directory block are claimed by the directory entries.  This
 * usually results in the last entry in a directory having a large
 * dp->d_reclen.  When entries are deleted from a directory, the
 * space is returned to the previous entry in the same directory
 * block by increasing its dp->d_reclen.  If the first entry of
 * a directory block is free, then its dp->d_ino is set to 0.
 * Entries other than the first in a directory do not normally have
 * dp->d_ino set to 0.
 */
#define	DIRBLKSIZ	DEV_BSIZE
#define	MAXNAMLEN	255

struct	direct {
	uint32_t	d_ino;		/* inode number of entry */
	ushort_t	d_reclen;	/* length of this record */
	ushort_t	d_namlen;	/* length of string in d_name */
	char	d_name[MAXNAMLEN + 1];	/* name must be no longer than this */
};

/*
 * The DIRSIZ macro gives the minimum record length which will hold
 * the directory entry.  This requires the amount of space in struct direct
 * without the d_name field, plus enough space for the name with a terminating
 * null byte (dp->d_namlen+1), rounded up to a 4 byte boundary.
 */
#undef DIRSIZ
#define	DIRSIZ(dp) \
	((sizeof (struct direct) - (MAXNAMLEN+1)) + (((dp)->d_namlen+1+3) &~ 3))

#ifdef _KERNEL
/*
 * Template for manipulating directories.
 * Should use struct direct's, but the name field
 * is MAXNAMLEN - 1, and this just won't do.
 */
struct dirtemplate {
	uint32_t	dot_ino;
	short		dot_reclen;
	short		dot_namlen;
	char		dot_name[4];		/* must be multiple of 4 */
	uint32_t	dotdot_ino;
	short		dotdot_reclen;
	short		dotdot_namlen;
	char		dotdot_name[4];		/* ditto */
};

/*
 * Reduced structure for manipulating directories.
 * Note, we are using __packed here to ensure the size of structure
 * without changing the alignment.
 */
struct tmp_dir {
	uint32_t	d_ino;		/* inode number of entry */
	ushort_t	d_reclen;	/* length of this record */
	ushort_t	d_namlen;	/* length of string in d_name */
	char		d_name[4];	/* name must be no longer than this */
} __packed;

#endif

#ifdef	__cplusplus
}
#endif

#endif	/* _SYS_FS_UFS_FSDIR_H */