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      1 /*	$NetBSD: fat.h,v 1.10 2021/10/23 16:58:17 thorpej Exp $	*/
      2 
      3 /*-
      4  * Copyright (C) 1994, 1997 Wolfgang Solfrank.
      5  * Copyright (C) 1994, 1997 TooLs GmbH.
      6  * All rights reserved.
      7  * Original code by Paul Popelka (paulp (at) uts.amdahl.com) (see below).
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  * 3. All advertising materials mentioning features or use of this software
     18  *    must display the following acknowledgement:
     19  *	This product includes software developed by TooLs GmbH.
     20  * 4. The name of TooLs GmbH may not be used to endorse or promote products
     21  *    derived from this software without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
     24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     25  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     26  * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     27  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     28  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     29  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     30  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     31  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     32  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     33  */
     34 /*
     35  * Written by Paul Popelka (paulp (at) uts.amdahl.com)
     36  *
     37  * You can do anything you want with this software, just don't say you wrote
     38  * it, and don't remove this notice.
     39  *
     40  * This software is provided "as is".
     41  *
     42  * The author supplies this software to be publicly redistributed on the
     43  * understanding that the author is not responsible for the correct
     44  * functioning of this software in any circumstances and is not liable for
     45  * any damages caused by this software.
     46  *
     47  * October 1992
     48  */
     49 
     50 #ifndef _MSDOSFS_FAT_H_
     51 #define _MSDOSFS_FAT_H_
     52 /*
     53  * Some useful cluster numbers.
     54  */
     55 #define	MSDOSFSROOT	0		/* cluster 0 means the root dir */
     56 #define	CLUST_FREE	0		/* cluster 0 also means a free cluster */
     57 #define	MSDOSFSFREE	CLUST_FREE
     58 #define	CLUST_FIRST	2		/* first legal cluster number */
     59 #define	CLUST_RSRVD	0xfffffff6	/* reserved cluster range */
     60 #define	CLUST_BAD	0xfffffff7	/* a cluster with a defect */
     61 #define	CLUST_EOFS	0xfffffff8	/* start of eof cluster range */
     62 #define	CLUST_EOFE	0xffffffff	/* end of eof cluster range */
     63 #define	CLUST_END	CLUST_EOFE	/* bigger than any valid cluster */
     64 
     65 #define	FAT12_MASK	0x00000fff	/* mask for 12 bit cluster numbers */
     66 #define	FAT16_MASK	0x0000ffff	/* mask for 16 bit cluster numbers */
     67 #define	FAT32_MASK	0x0fffffff	/* mask for FAT32 cluster numbers */
     68 
     69 /*
     70  * MSDOSFS:
     71  * Return true if filesystem uses 12 bit FATs. Microsoft Programmer's
     72  * Reference says if the maximum cluster number in a filesystem is greater
     73  * than 4084 ((CLUST_RSRVD - CLUST_FIRST) & FAT12_MASK) then we've got a
     74  * 16 bit FAT filesystem. While mounting, the result of this test is stored
     75  * in pm_fatentrysize.
     76  * GEMDOS-flavour (atari):
     77  * If the filesystem is on floppy we've got a 12 bit FAT filesystem, otherwise
     78  * 16 bit. We check the d_type field in the disklabel struct while mounting
     79  * and store the result in the pm_fatentrysize. Note that this kind of
     80  * detection gets flakey when mounting a vnd-device.
     81  */
     82 #define	FAT12(pmp)	(pmp->pm_fatmask == FAT12_MASK)
     83 #define	FAT16(pmp)	(pmp->pm_fatmask == FAT16_MASK)
     84 #define	FAT32(pmp)	(pmp->pm_fatmask == FAT32_MASK)
     85 
     86 /*
     87  * M$ in its unlimited wisdom decided that EOF mark is anything
     88  * between 0xfffffff8 and 0xffffffff (masked by appropriate fatmask,
     89  * of course).
     90  * Note that cn is supposed to be already adjusted accordingly to FAT type.
     91  */
     92 #define	MSDOSFSEOF(cn, fatmask)	\
     93 	(((cn) & CLUST_EOFS) == (CLUST_EOFS & (fatmask)))
     94 
     95 #if defined(_KERNEL) || defined(MAKEFS)
     96 /*
     97  * These are the values for the function argument to the function
     98  * fatentry().
     99  */
    100 #define	FAT_GET		0x0001	/* get a FAT entry */
    101 #define	FAT_SET		0x0002	/* set a FAT entry */
    102 #define	FAT_GET_AND_SET	(FAT_GET | FAT_SET)
    103 
    104 /*
    105  * Flags to extendfile:
    106  */
    107 #define	DE_CLEAR	1	/* Zero out the blocks allocated */
    108 
    109 int	msdosfs_pcbmap(struct denode *, u_long, daddr_t *, u_long *, int *);
    110 int	msdosfs_clusterfree(struct msdosfsmount *, u_long, u_long *);
    111 int	msdosfs_clusteralloc(struct msdosfsmount *, u_long, u_long, u_long *,
    112 	    u_long *);
    113 int	msdosfs_extendfile(struct denode *, u_long, struct buf **, u_long *,
    114 	    int);
    115 int	msdosfs_fatentry(int, struct msdosfsmount *, u_long, u_long *, u_long);
    116 void	msdosfs_fc_purge(struct denode *, u_int);
    117 void	msdosfs_fc_lookup(struct denode *, u_long, u_long *, u_long *);
    118 int	msdosfs_fillinusemap(struct msdosfsmount *);
    119 int	msdosfs_freeclusterchain(struct msdosfsmount *, u_long);
    120 #endif /* _KERNEL || MAKEFS */
    121 #endif /* _MSDOSFS_FAT_H_ */
    122