1/*	$NetBSD: msdosfs_denode.c,v 1.8 2021/10/23 16:58:17 thorpej Exp $	*/
2
3/*-
4 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
5 * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
6 * All rights reserved.
7 * Original code by Paul Popelka (paulp@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@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#if HAVE_NBTOOL_CONFIG_H
51#include "nbtool_config.h"
52#endif
53
54#include <sys/cdefs.h>
55__KERNEL_RCSID(0, "$NetBSD: msdosfs_denode.c,v 1.8 2021/10/23 16:58:17 thorpej Exp $");
56
57#include <sys/param.h>
58
59#include <ffs/buf.h>
60
61#include <fs/msdosfs/bpb.h>
62#include <fs/msdosfs/msdosfsmount.h>
63#include <fs/msdosfs/direntry.h>
64#include <fs/msdosfs/denode.h>
65#include <fs/msdosfs/fat.h>
66
67#include <util.h>
68
69/*
70 * If deget() succeeds it returns with the gotten denode locked().
71 *
72 * pmp	     - address of msdosfsmount structure of the filesystem containing
73 *	       the denode of interest.  The pm_dev field and the address of
74 *	       the msdosfsmount structure are used.
75 * dirclust  - which cluster bp contains, if dirclust is 0 (root directory)
76 *	       diroffset is relative to the beginning of the root directory,
77 *	       otherwise it is cluster relative.
78 * diroffset - offset past begin of cluster of denode we want
79 * depp	     - returns the address of the gotten denode.
80 */
81int
82msdosfs_deget(struct msdosfsmount *pmp, u_long dirclust, u_long diroffset,
83    struct denode **depp)
84	/* pmp:	 so we know the maj/min number */
85	/* dirclust:		 cluster this dir entry came from */
86	/* diroffset:		 index of entry within the cluster */
87	/* depp:		 returns the addr of the gotten denode */
88{
89	int error;
90	struct direntry *direntptr;
91	struct denode *ldep;
92	struct buf *bp;
93
94#ifdef MSDOSFS_DEBUG
95	printf("deget(pmp %p, dirclust %lu, diroffset %lx, depp %p)\n",
96	    pmp, dirclust, diroffset, depp);
97#endif
98
99	/*
100	 * On FAT32 filesystems, root is a (more or less) normal
101	 * directory
102	 */
103	if (FAT32(pmp) && dirclust == MSDOSFSROOT)
104		dirclust = pmp->pm_rootdirblk;
105
106	ldep = ecalloc(1, sizeof(*ldep));
107	ldep->de_vnode = NULL;
108	ldep->de_flag = 0;
109	ldep->de_devvp = 0;
110	ldep->de_lockf = 0;
111	ldep->de_dev = pmp->pm_dev;
112	ldep->de_dirclust = dirclust;
113	ldep->de_diroffset = diroffset;
114	ldep->de_pmp = pmp;
115	ldep->de_devvp = pmp->pm_devvp;
116	ldep->de_refcnt = 1;
117	msdosfs_fc_purge(ldep, 0);
118	/*
119	 * Copy the directory entry into the denode area of the vnode.
120	 */
121	if ((dirclust == MSDOSFSROOT
122	     || (FAT32(pmp) && dirclust == pmp->pm_rootdirblk))
123	    && diroffset == MSDOSFSROOT_OFS) {
124		/*
125		 * Directory entry for the root directory. There isn't one,
126		 * so we manufacture one. We should probably rummage
127		 * through the root directory and find a label entry (if it
128		 * exists), and then use the time and date from that entry
129		 * as the time and date for the root denode.
130		 */
131		ldep->de_vnode = (struct vnode *)-1;
132
133		ldep->de_Attributes = ATTR_DIRECTORY;
134		if (FAT32(pmp))
135			ldep->de_StartCluster = pmp->pm_rootdirblk;
136			/* de_FileSize will be filled in further down */
137		else {
138			ldep->de_StartCluster = MSDOSFSROOT;
139			ldep->de_FileSize = pmp->pm_rootdirsize * pmp->pm_BytesPerSec;
140		}
141		/*
142		 * fill in time and date so that dos2unixtime() doesn't
143		 * spit up when called from msdosfs_getattr() with root
144		 * denode
145		 */
146		ldep->de_CHun = 0;
147		ldep->de_CTime = 0x0000;	/* 00:00:00	 */
148		ldep->de_CDate = (0 << DD_YEAR_SHIFT) | (1 << DD_MONTH_SHIFT)
149		    | (1 << DD_DAY_SHIFT);
150		/* Jan 1, 1980	 */
151		ldep->de_ADate = ldep->de_CDate;
152		ldep->de_MTime = ldep->de_CTime;
153		ldep->de_MDate = ldep->de_CDate;
154		/* leave the other fields as garbage */
155	} else {
156		error = msdosfs_readep(pmp, dirclust, diroffset, &bp,
157		    &direntptr);
158		if (error) {
159			ldep->de_devvp = NULL;
160			ldep->de_Name[0] = SLOT_DELETED;
161			return (error);
162		}
163		DE_INTERNALIZE(ldep, direntptr);
164		brelse(bp, 0);
165	}
166
167	/*
168	 * Fill in a few fields of the vnode and finish filling in the
169	 * denode.  Then return the address of the found denode.
170	 */
171	if (ldep->de_Attributes & ATTR_DIRECTORY) {
172		/*
173		 * Since DOS directory entries that describe directories
174		 * have 0 in the filesize field, we take this opportunity
175		 * to find out the length of the directory and plug it into
176		 * the denode structure.
177		 */
178		u_long size;
179
180		if (ldep->de_StartCluster != MSDOSFSROOT) {
181			error = msdosfs_pcbmap(ldep, CLUST_END, 0, &size, 0);
182			if (error == E2BIG) {
183				ldep->de_FileSize = de_cn2off(pmp, size);
184				error = 0;
185			} else
186				printf("deget(): pcbmap returned %d\n", error);
187		}
188	}
189	*depp = ldep;
190	return (0);
191}
192
193/*
194 * Truncate the file described by dep to the length specified by length.
195 */
196int
197msdosfs_detrunc(struct denode *dep, u_long length, int flags,
198    struct kauth_cred *cred)
199{
200	int error;
201	int allerror = 0;
202	u_long eofentry;
203	u_long chaintofree = 0;
204	daddr_t bn, lastblock;
205	int boff;
206	int isadir = dep->de_Attributes & ATTR_DIRECTORY;
207	struct buf *bp;
208	struct msdosfsmount *pmp = dep->de_pmp;
209
210#ifdef MSDOSFS_DEBUG
211	printf("detrunc(): file %s, length %lu, flags %x\n", dep->de_Name, length, flags);
212#endif
213
214	/*
215	 * Disallow attempts to truncate the root directory since it is of
216	 * fixed size.  That's just the way dos filesystems are.  We use
217	 * the VROOT bit in the vnode because checking for the directory
218	 * bit and a startcluster of 0 in the denode is not adequate to
219	 * recognize the root directory at this point in a file or
220	 * directory's life.
221	 */
222	if (dep->de_vnode != NULL && !FAT32(pmp)) {
223		printf("detrunc(): can't truncate root directory, clust %ld, offset %ld\n",
224		    dep->de_dirclust, dep->de_diroffset);
225		return (EINVAL);
226	}
227
228	if (dep->de_FileSize < length)
229		return (msdosfs_deextend(dep, length, cred));
230	lastblock = de_clcount(pmp, length) - 1;
231
232	/*
233	 * If the desired length is 0 then remember the starting cluster of
234	 * the file and set the StartCluster field in the directory entry
235	 * to 0.  If the desired length is not zero, then get the number of
236	 * the last cluster in the shortened file.  Then get the number of
237	 * the first cluster in the part of the file that is to be freed.
238	 * Then set the next cluster pointer in the last cluster of the
239	 * file to CLUST_EOFE.
240	 */
241	if (length == 0) {
242		chaintofree = dep->de_StartCluster;
243		dep->de_StartCluster = 0;
244		eofentry = ~0;
245	} else {
246		error = msdosfs_pcbmap(dep, lastblock, 0, &eofentry, 0);
247		if (error) {
248#ifdef MSDOSFS_DEBUG
249			printf("detrunc(): pcbmap fails %d\n", error);
250#endif
251			return (error);
252		}
253	}
254
255	/*
256	 * If the new length is not a multiple of the cluster size then we
257	 * must zero the tail end of the new last cluster in case it
258	 * becomes part of the file again because of a seek.
259	 */
260	if ((boff = length & pmp->pm_crbomask) != 0) {
261		if (isadir) {
262			bn = cntobn(pmp, eofentry);
263			error = bread(pmp->pm_devvp, de_bn2kb(pmp, bn),
264			    pmp->pm_bpcluster, B_MODIFY, &bp);
265			if (error) {
266#ifdef MSDOSFS_DEBUG
267				printf("detrunc(): bread fails %d\n", error);
268#endif
269				return (error);
270			}
271			memset((char *)bp->b_data + boff, 0,
272			    pmp->pm_bpcluster - boff);
273			if (flags & IO_SYNC)
274				bwrite(bp);
275			else
276				bdwrite(bp);
277		}
278	}
279
280	/*
281	 * Write out the updated directory entry.  Even if the update fails
282	 * we free the trailing clusters.
283	 */
284	dep->de_FileSize = length;
285	if (!isadir)
286		dep->de_flag |= DE_UPDATE|DE_MODIFIED;
287#ifdef MSDOSFS_DEBUG
288	printf("detrunc(): allerror %d, eofentry %lu\n",
289	       allerror, eofentry);
290#endif
291
292	/*
293	 * If we need to break the cluster chain for the file then do it
294	 * now.
295	 */
296	if (eofentry != (u_long)~0) {
297		error = msdosfs_fatentry(FAT_GET_AND_SET, pmp, eofentry,
298				 &chaintofree, CLUST_EOFE);
299		if (error) {
300#ifdef MSDOSFS_DEBUG
301			printf("detrunc(): fatentry errors %d\n", error);
302#endif
303			return (error);
304		}
305	}
306
307	/*
308	 * Now free the clusters removed from the file because of the
309	 * truncation.
310	 */
311	if (chaintofree != 0 && !MSDOSFSEOF(chaintofree, pmp->pm_fatmask))
312		msdosfs_freeclusterchain(pmp, chaintofree);
313
314	return (allerror);
315}
316
317/*
318 * Extend the file described by dep to length specified by length.
319 */
320int
321msdosfs_deextend(struct denode *dep, u_long length, struct kauth_cred *cred)
322{
323	struct msdosfsmount *pmp = dep->de_pmp;
324	u_long count;
325	int error;
326
327	/*
328	 * The root of a DOS filesystem cannot be extended.
329	 */
330	if (dep->de_vnode != NULL && !FAT32(pmp))
331		return EINVAL;
332
333	/*
334	 * Directories cannot be extended.
335	 */
336	if (dep->de_Attributes & ATTR_DIRECTORY)
337		return EISDIR;
338
339	if (length <= dep->de_FileSize)
340		return E2BIG;
341
342	/*
343	 * Compute the number of clusters to allocate.
344	 */
345	count = de_clcount(pmp, length) - de_clcount(pmp, dep->de_FileSize);
346	if (count > 0) {
347		if (count > pmp->pm_freeclustercount)
348			return (ENOSPC);
349		error = msdosfs_extendfile(dep, count, NULL, NULL, DE_CLEAR);
350		if (error) {
351			/* truncate the added clusters away again */
352			(void) msdosfs_detrunc(dep, dep->de_FileSize, 0, cred);
353			return (error);
354		}
355	}
356
357	/*
358	 * Zero extend file range; ubc_zerorange() uses ubc_alloc() and a
359	 * memset(); we set the write size so ubc won't read in file data that
360	 * is zero'd later.
361	 */
362	dep->de_FileSize = length;
363	dep->de_flag |= DE_UPDATE|DE_MODIFIED;
364	return 0;
365}
366