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/param.h>
53 #include <sys/errno.h>
54
55 #include <stdbool.h>
56 #include <stdio.h>
57 #include <string.h>
58 #include <stdlib.h>
59 #include <util.h>
60
61 #include <fs/msdosfs/bpb.h>
62 #include "msdos/denode.h"
63 #include <fs/msdosfs/fat.h>
64 #include <fs/msdosfs/msdosfsmount.h>
65
66 #include "makefs.h"
67 #include "msdos.h"
68
69
70 /*
71 * If deget() succeeds it returns with the gotten denode locked().
72 *
73 * pmp - address of msdosfsmount structure of the filesystem containing
74 * the denode of interest. The pm_dev field and the address of
75 * the msdosfsmount structure are used.
76 * dirclust - which cluster bp contains, if dirclust is 0 (root directory)
77 * diroffset is relative to the beginning of the root directory,
78 * otherwise it is cluster relative.
79 * diroffset - offset past begin of cluster of denode we want
80 * depp - returns the address of the gotten denode.
81 */
82 int
deget(struct msdosfsmount * pmp,u_long dirclust,u_long diroffset,int lkflags __unused,struct denode ** depp)83 deget(struct msdosfsmount *pmp, u_long dirclust, u_long diroffset,
84 int lkflags __unused, struct denode **depp)
85 {
86 int error;
87 uint64_t inode;
88 struct direntry *direntptr;
89 struct denode *ldep;
90 struct m_buf *bp;
91
92 MSDOSFS_DPRINTF(("deget(pmp %p, dirclust %lu, diroffset %lx, depp %p)\n",
93 pmp, dirclust, diroffset, depp));
94
95 /*
96 * On FAT32 filesystems, root is a (more or less) normal
97 * directory
98 */
99 if (FAT32(pmp) && dirclust == MSDOSFSROOT)
100 dirclust = pmp->pm_rootdirblk;
101
102 inode = (uint64_t)pmp->pm_bpcluster * dirclust + diroffset;
103
104 ldep = ecalloc(1, sizeof(*ldep));
105 ldep->de_vnode = NULL;
106 ldep->de_flag = 0;
107 ldep->de_dirclust = dirclust;
108 ldep->de_diroffset = diroffset;
109 ldep->de_inode = inode;
110 ldep->de_pmp = pmp;
111 ldep->de_refcnt = 1;
112 fc_purge(ldep, 0); /* init the FAT cache for this denode */
113 /*
114 * Copy the directory entry into the denode area of the vnode.
115 */
116 if ((dirclust == MSDOSFSROOT
117 || (FAT32(pmp) && dirclust == pmp->pm_rootdirblk))
118 && diroffset == MSDOSFSROOT_OFS) {
119 /*
120 * Directory entry for the root directory. There isn't one,
121 * so we manufacture one. We should probably rummage
122 * through the root directory and find a label entry (if it
123 * exists), and then use the time and date from that entry
124 * as the time and date for the root denode.
125 */
126 ldep->de_vnode = (struct vnode *)-1;
127
128 ldep->de_Attributes = ATTR_DIRECTORY;
129 ldep->de_LowerCase = 0;
130 if (FAT32(pmp))
131 ldep->de_StartCluster = pmp->pm_rootdirblk;
132 /* de_FileSize will be filled in further down */
133 else {
134 ldep->de_StartCluster = MSDOSFSROOT;
135 ldep->de_FileSize = pmp->pm_rootdirsize * DEV_BSIZE;
136 }
137 /*
138 * fill in time and date so that dos2unixtime() doesn't
139 * spit up when called from msdosfs_getattr() with root
140 * denode
141 */
142 ldep->de_CHun = 0;
143 ldep->de_CTime = 0x0000; /* 00:00:00 */
144 ldep->de_CDate = (0 << DD_YEAR_SHIFT) | (1 << DD_MONTH_SHIFT)
145 | (1 << DD_DAY_SHIFT);
146 /* Jan 1, 1980 */
147 ldep->de_ADate = ldep->de_CDate;
148 ldep->de_MTime = ldep->de_CTime;
149 ldep->de_MDate = ldep->de_CDate;
150 /* leave the other fields as garbage */
151 } else {
152 error = m_readep(pmp, dirclust, diroffset, &bp, &direntptr);
153 if (error) {
154 ldep->de_Name[0] = SLOT_DELETED;
155
156 *depp = NULL;
157 return (error);
158 }
159 (void)DE_INTERNALIZE(ldep, direntptr);
160 brelse(bp);
161 }
162
163 /*
164 * Fill in a few fields of the vnode and finish filling in the
165 * denode. Then return the address of the found denode.
166 */
167 if (ldep->de_Attributes & ATTR_DIRECTORY) {
168 /*
169 * Since DOS directory entries that describe directories
170 * have 0 in the filesize field, we take this opportunity
171 * to find out the length of the directory and plug it into
172 * the denode structure.
173 */
174 u_long size;
175
176 /*
177 * XXX it sometimes happens that the "." entry has cluster
178 * number 0 when it shouldn't. Use the actual cluster number
179 * instead of what is written in directory entry.
180 */
181 if (diroffset == 0 && ldep->de_StartCluster != dirclust) {
182 MSDOSFS_DPRINTF(("deget(): \".\" entry at clust %lu != %lu\n",
183 dirclust, ldep->de_StartCluster));
184
185 ldep->de_StartCluster = dirclust;
186 }
187
188 if (ldep->de_StartCluster != MSDOSFSROOT) {
189 error = pcbmap(ldep, 0xffff, 0, &size, 0);
190 if (error == E2BIG) {
191 ldep->de_FileSize = de_cn2off(pmp, size);
192 error = 0;
193 } else {
194 MSDOSFS_DPRINTF(("deget(): pcbmap returned %d\n",
195 error));
196 }
197 }
198 }
199 *depp = ldep;
200 return (0);
201 }
202
203 /*
204 * Truncate the file described by dep to the length specified by length.
205 */
206 int
detrunc(struct denode * dep,u_long length,int flags,struct ucred * cred)207 detrunc(struct denode *dep, u_long length, int flags, struct ucred *cred)
208 {
209 int error;
210 u_long eofentry;
211 u_long chaintofree;
212 daddr_t bn;
213 int boff;
214 int isadir = dep->de_Attributes & ATTR_DIRECTORY;
215 struct m_buf *bp;
216 struct msdosfsmount *pmp = dep->de_pmp;
217
218 MSDOSFS_DPRINTF(("detrunc(): file %s, length %lu, flags %x\n",
219 dep->de_Name, length, flags));
220
221 /*
222 * Disallow attempts to truncate the root directory since it is of
223 * fixed size. That's just the way dos filesystems are. We use
224 * the VROOT bit in the vnode because checking for the directory
225 * bit and a startcluster of 0 in the denode is not adequate to
226 * recognize the root directory at this point in a file or
227 * directory's life.
228 */
229 if (dep->de_vnode != NULL && !FAT32(pmp)) {
230 MSDOSFS_DPRINTF(("detrunc(): can't truncate root directory, "
231 "clust %ld, offset %ld\n",
232 dep->de_dirclust, dep->de_diroffset));
233
234 return (EINVAL);
235 }
236
237 if (dep->de_FileSize < length)
238 return deextend(dep, length, cred);
239
240 /*
241 * If the desired length is 0 then remember the starting cluster of
242 * the file and set the StartCluster field in the directory entry
243 * to 0. If the desired length is not zero, then get the number of
244 * the last cluster in the shortened file. Then get the number of
245 * the first cluster in the part of the file that is to be freed.
246 * Then set the next cluster pointer in the last cluster of the
247 * file to CLUST_EOFE.
248 */
249 if (length == 0) {
250 chaintofree = dep->de_StartCluster;
251 dep->de_StartCluster = 0;
252 eofentry = ~0ul;
253 } else {
254 error = pcbmap(dep, de_clcount(pmp, length) - 1, 0,
255 &eofentry, 0);
256 if (error) {
257 MSDOSFS_DPRINTF(("detrunc(): pcbmap fails %d\n",
258 error));
259 return (error);
260 }
261 }
262
263 fc_purge(dep, de_clcount(pmp, length));
264
265 /*
266 * If the new length is not a multiple of the cluster size then we
267 * must zero the tail end of the new last cluster in case it
268 * becomes part of the file again because of a seek.
269 */
270 if ((boff = length & pmp->pm_crbomask) != 0) {
271 if (isadir) {
272 bn = cntobn(pmp, eofentry);
273 error = bread((void *)pmp->pm_devvp, bn,
274 pmp->pm_bpcluster, 0, &bp);
275 if (error) {
276 brelse(bp);
277 MSDOSFS_DPRINTF(("detrunc(): bread fails %d\n",
278 error));
279
280 return (error);
281 }
282 memset(bp->b_data + boff, 0, pmp->pm_bpcluster - boff);
283 bwrite(bp);
284 }
285 }
286
287 /*
288 * Write out the updated directory entry. Even if the update fails
289 * we free the trailing clusters.
290 */
291 dep->de_FileSize = length;
292 if (!isadir)
293 dep->de_flag |= DE_UPDATE|DE_MODIFIED;
294 MSDOSFS_DPRINTF(("detrunc(): eofentry %lu\n", eofentry));
295
296 /*
297 * If we need to break the cluster chain for the file then do it
298 * now.
299 */
300 if (eofentry != ~0ul) {
301 error = fatentry(FAT_GET_AND_SET, pmp, eofentry,
302 &chaintofree, CLUST_EOFE);
303 if (error) {
304 MSDOSFS_DPRINTF(("detrunc(): fatentry errors %d\n",
305 error));
306 return (error);
307 }
308 fc_setcache(dep, FC_LASTFC, de_cluster(pmp, length - 1),
309 eofentry);
310 }
311
312 /*
313 * Now free the clusters removed from the file because of the
314 * truncation.
315 */
316 if (chaintofree != 0 && !MSDOSFSEOF(pmp, chaintofree))
317 freeclusterchain(pmp, chaintofree);
318
319 return (0);
320 }
321
322 /*
323 * Extend the file described by dep to length specified by length.
324 */
325 int
deextend(struct denode * dep,u_long length,struct ucred * cred)326 deextend(struct denode *dep, u_long length, struct ucred *cred)
327 {
328 struct msdosfsmount *pmp = dep->de_pmp;
329 u_long count;
330 int error;
331
332 /*
333 * The root of a DOS filesystem cannot be extended.
334 */
335 if (dep->de_vnode != NULL && !FAT32(pmp))
336 return (EINVAL);
337
338 /*
339 * Directories cannot be extended.
340 */
341 if (dep->de_Attributes & ATTR_DIRECTORY)
342 return (EISDIR);
343
344 if (length <= dep->de_FileSize)
345 return (E2BIG);
346
347 /*
348 * Compute the number of clusters to allocate.
349 */
350 count = de_clcount(pmp, length) - de_clcount(pmp, dep->de_FileSize);
351 if (count > 0) {
352 if (count > pmp->pm_freeclustercount)
353 return (ENOSPC);
354 error = m_extendfile(dep, count, NULL, NULL, DE_CLEAR);
355 if (error) {
356 /* truncate the added clusters away again */
357 (void) detrunc(dep, dep->de_FileSize, 0, cred);
358 return (error);
359 }
360 }
361
362 /*
363 * Zero extend file range; ubc_zerorange() uses ubc_alloc() and a
364 * memset(); we set the write size so ubc won't read in file data that
365 * is zero'd later.
366 */
367 dep->de_FileSize = length;
368 dep->de_flag |= DE_UPDATE | DE_MODIFIED;
369 return 0;
370 }
371