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 */
81 int
msdosfs_deget(struct msdosfsmount * pmp,u_long dirclust,u_long diroffset,struct denode ** depp)82 msdosfs_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 */
196 int
msdosfs_detrunc(struct denode * dep,u_long length,int flags,struct kauth_cred * cred)197 msdosfs_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 */
320 int
msdosfs_deextend(struct denode * dep,u_long length,struct kauth_cred * cred)321 msdosfs_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