1 /* $NetBSD: msdosfs_denode.c,v 1.7 2015/03/29 05:52:59 agc Exp $ */
2
3 /*-
4 * SPDX-License-Identifier: BSD-4-Clause
5 *
6 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
7 * Copyright (C) 1994, 1995, 1997 TooLs GmbH.
8 * All rights reserved.
9 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below).
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. All advertising materials mentioning features or use of this software
20 * must display the following acknowledgement:
21 * This product includes software developed by TooLs GmbH.
22 * 4. The name of TooLs GmbH may not be used to endorse or promote products
23 * derived from this software without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR
26 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
27 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
28 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
29 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
30 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
31 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
32 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
33 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
34 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35 */
36 /*-
37 * Written by Paul Popelka (paulp@uts.amdahl.com)
38 *
39 * You can do anything you want with this software, just don't say you wrote
40 * it, and don't remove this notice.
41 *
42 * This software is provided "as is".
43 *
44 * The author supplies this software to be publicly redistributed on the
45 * understanding that the author is not responsible for the correct
46 * functioning of this software in any circumstances and is not liable for
47 * any damages caused by this software.
48 *
49 * October 1992
50 */
51
52 #include <sys/cdefs.h>
53 __FBSDID("$FreeBSD$");
54
55 #include <sys/param.h>
56 #include <sys/errno.h>
57
58 #include <stdbool.h>
59 #include <stdio.h>
60 #include <string.h>
61 #include <stdlib.h>
62 #include <util.h>
63
64 #include <vfs/msdosfs/bpb.h>
65 #include "msdos/denode.h"
66 #include <vfs/msdosfs/fat.h>
67 #include <vfs/msdosfs/msdosfsmount.h>
68
69 #include "makefs.h"
70 #include "msdos.h"
71
72
73 /*
74 * If deget() succeeds it returns with the gotten denode locked().
75 *
76 * pmp - address of msdosfsmount structure of the filesystem containing
77 * the denode of interest. The pm_dev field and the address of
78 * the msdosfsmount structure are used.
79 * dirclust - which cluster bp contains, if dirclust is 0 (root directory)
80 * diroffset is relative to the beginning of the root directory,
81 * otherwise it is cluster relative.
82 * diroffset - offset past begin of cluster of denode we want
83 * depp - returns the address of the gotten denode.
84 */
85 int
deget(struct msdosfsmount * pmp,u_long dirclust,u_long diroffset,struct denode ** depp)86 deget(struct msdosfsmount *pmp, u_long dirclust, u_long diroffset,
87 struct denode **depp)
88 {
89 int error;
90 uint64_t inode;
91 struct direntry *direntptr;
92 struct denode *ldep;
93 struct m_buf *bp;
94
95 MSDOSFS_DPRINTF(("deget(pmp %p, dirclust %lu, diroffset %lx, depp %p)\n",
96 pmp, dirclust, diroffset, depp));
97
98 /*
99 * On FAT32 filesystems, root is a (more or less) normal
100 * directory
101 */
102 if (FAT32(pmp) && dirclust == MSDOSFSROOT)
103 dirclust = pmp->pm_rootdirblk;
104
105 inode = (uint64_t)pmp->pm_bpcluster * dirclust + diroffset;
106
107 ldep = ecalloc(1, sizeof(*ldep));
108 ldep->de_vnode = NULL;
109 ldep->de_flag = 0;
110 ldep->de_dirclust = dirclust;
111 ldep->de_diroffset = diroffset;
112 /* XXX unused + non existent in DragonFly */
113 //ldep->de_inode = inode;
114 ldep->de_pmp = pmp;
115 ldep->de_refcnt = 1;
116 fc_purge(ldep, 0); /* init the FAT cache for this denode */
117 /*
118 * Copy the directory entry into the denode area of the vnode.
119 */
120 if ((dirclust == MSDOSFSROOT
121 || (FAT32(pmp) && dirclust == pmp->pm_rootdirblk))
122 && diroffset == MSDOSFSROOT_OFS) {
123 /*
124 * Directory entry for the root directory. There isn't one,
125 * so we manufacture one. We should probably rummage
126 * through the root directory and find a label entry (if it
127 * exists), and then use the time and date from that entry
128 * as the time and date for the root denode.
129 */
130 ldep->de_vnode = (struct vnode *)-1;
131
132 ldep->de_Attributes = ATTR_DIRECTORY;
133 ldep->de_LowerCase = 0;
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 * DEV_BSIZE;
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 = m_readep(pmp, dirclust, diroffset, &bp, &direntptr);
157 if (error) {
158 ldep->de_Name[0] = SLOT_DELETED;
159
160 *depp = NULL;
161 return (error);
162 }
163 (void)DE_INTERNALIZE(ldep, direntptr);
164 brelse(bp);
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 /*
181 * XXX it sometimes happens that the "." entry has cluster
182 * number 0 when it shouldn't. Use the actual cluster number
183 * instead of what is written in directory entry.
184 */
185 if (diroffset == 0 && ldep->de_StartCluster != dirclust) {
186 MSDOSFS_DPRINTF(("deget(): \".\" entry at clust %lu != %lu\n",
187 dirclust, ldep->de_StartCluster));
188
189 ldep->de_StartCluster = dirclust;
190 }
191
192 if (ldep->de_StartCluster != MSDOSFSROOT) {
193 error = pcbmap(ldep, 0xffff, 0, &size, 0);
194 if (error == E2BIG) {
195 ldep->de_FileSize = de_cn2off(pmp, size);
196 error = 0;
197 } else {
198 MSDOSFS_DPRINTF(("deget(): pcbmap returned %d\n",
199 error));
200 }
201 }
202 }
203 *depp = ldep;
204 return (0);
205 }
206
207 /*
208 * Truncate the file described by dep to the length specified by length.
209 */
210 int
detrunc(struct denode * dep,u_long length,int flags)211 detrunc(struct denode *dep, u_long length, int flags)
212 {
213 int error;
214 u_long eofentry;
215 u_long chaintofree;
216 daddr_t bn;
217 int boff;
218 int isadir = dep->de_Attributes & ATTR_DIRECTORY;
219 struct m_buf *bp;
220 struct msdosfsmount *pmp = dep->de_pmp;
221
222 MSDOSFS_DPRINTF(("detrunc(): file %s, length %lu, flags %x\n",
223 dep->de_Name, length, flags));
224
225 /*
226 * Disallow attempts to truncate the root directory since it is of
227 * fixed size. That's just the way dos filesystems are. We use
228 * the VROOT bit in the vnode because checking for the directory
229 * bit and a startcluster of 0 in the denode is not adequate to
230 * recognize the root directory at this point in a file or
231 * directory's life.
232 */
233 if (dep->de_vnode != NULL && !FAT32(pmp)) {
234 MSDOSFS_DPRINTF(("detrunc(): can't truncate root directory, "
235 "clust %ld, offset %ld\n",
236 dep->de_dirclust, dep->de_diroffset));
237
238 return (EINVAL);
239 }
240
241 if (dep->de_FileSize < length)
242 return deextend(dep, length);
243
244 /*
245 * If the desired length is 0 then remember the starting cluster of
246 * the file and set the StartCluster field in the directory entry
247 * to 0. If the desired length is not zero, then get the number of
248 * the last cluster in the shortened file. Then get the number of
249 * the first cluster in the part of the file that is to be freed.
250 * Then set the next cluster pointer in the last cluster of the
251 * file to CLUST_EOFE.
252 */
253 if (length == 0) {
254 chaintofree = dep->de_StartCluster;
255 dep->de_StartCluster = 0;
256 eofentry = ~0ul;
257 } else {
258 error = pcbmap(dep, de_clcount(pmp, length) - 1, 0,
259 &eofentry, 0);
260 if (error) {
261 MSDOSFS_DPRINTF(("detrunc(): pcbmap fails %d\n",
262 error));
263 return (error);
264 }
265 }
266
267 fc_purge(dep, de_clcount(pmp, length));
268
269 /*
270 * If the new length is not a multiple of the cluster size then we
271 * must zero the tail end of the new last cluster in case it
272 * becomes part of the file again because of a seek.
273 */
274 if ((boff = length & pmp->pm_crbomask) != 0) {
275 if (isadir) {
276 bn = cntobn(pmp, eofentry);
277 error = bread((void *)pmp->pm_devvp, bn,
278 pmp->pm_bpcluster, 0, &bp);
279 if (error) {
280 brelse(bp);
281 MSDOSFS_DPRINTF(("detrunc(): bread fails %d\n",
282 error));
283
284 return (error);
285 }
286 memset(bp->b_data + boff, 0, pmp->pm_bpcluster - boff);
287 bwrite(bp);
288 }
289 }
290
291 /*
292 * Write out the updated directory entry. Even if the update fails
293 * we free the trailing clusters.
294 */
295 dep->de_FileSize = length;
296 if (!isadir)
297 dep->de_flag |= DE_UPDATE|DE_MODIFIED;
298 MSDOSFS_DPRINTF(("detrunc(): eofentry %lu\n", eofentry));
299
300 /*
301 * If we need to break the cluster chain for the file then do it
302 * now.
303 */
304 if (eofentry != ~0ul) {
305 error = fatentry(FAT_GET_AND_SET, pmp, eofentry,
306 &chaintofree, CLUST_EOFE);
307 if (error) {
308 MSDOSFS_DPRINTF(("detrunc(): fatentry errors %d\n",
309 error));
310 return (error);
311 }
312 fc_setcache(dep, FC_LASTFC, de_cluster(pmp, length - 1),
313 eofentry);
314 }
315
316 /*
317 * Now free the clusters removed from the file because of the
318 * truncation.
319 */
320 if (chaintofree != 0 && !MSDOSFSEOF(pmp, chaintofree))
321 freeclusterchain(pmp, chaintofree);
322
323 return (0);
324 }
325
326 /*
327 * Extend the file described by dep to length specified by length.
328 */
329 int
deextend(struct denode * dep,u_long length)330 deextend(struct denode *dep, u_long length)
331 {
332 struct msdosfsmount *pmp = dep->de_pmp;
333 u_long count;
334 int error;
335
336 /*
337 * The root of a DOS filesystem cannot be extended.
338 */
339 if (dep->de_vnode != NULL && !FAT32(pmp))
340 return (EINVAL);
341
342 /*
343 * Directories cannot be extended.
344 */
345 if (dep->de_Attributes & ATTR_DIRECTORY)
346 return (EISDIR);
347
348 if (length <= dep->de_FileSize)
349 return (E2BIG);
350
351 /*
352 * Compute the number of clusters to allocate.
353 */
354 count = de_clcount(pmp, length) - de_clcount(pmp, dep->de_FileSize);
355 if (count > 0) {
356 if (count > pmp->pm_freeclustercount)
357 return (ENOSPC);
358 error = m_extendfile(dep, count, NULL, NULL, DE_CLEAR);
359 if (error) {
360 /* truncate the added clusters away again */
361 (void) detrunc(dep, dep->de_FileSize, 0);
362 return (error);
363 }
364 }
365
366 /*
367 * Zero extend file range; ubc_zerorange() uses ubc_alloc() and a
368 * memset(); we set the write size so ubc won't read in file data that
369 * is zero'd later.
370 */
371 dep->de_FileSize = length;
372 dep->de_flag |= DE_UPDATE | DE_MODIFIED;
373 return 0;
374 }
375