1 /* $NetBSD: msdosfs_denode.c,v 1.7 2015/03/29 05:52:59 agc 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 1.7 2015/03/29 05:52:59 agc 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
deget(struct msdosfsmount * pmp,u_long dirclust,u_long diroffset,struct denode ** depp)82 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 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 = readep(pmp, dirclust, diroffset, &bp, &direntptr);
157 if (error) {
158 ldep->de_devvp = NULL;
159 ldep->de_Name[0] = SLOT_DELETED;
160 return (error);
161 }
162 DE_INTERNALIZE(ldep, direntptr);
163 brelse(bp, 0);
164 }
165
166 /*
167 * Fill in a few fields of the vnode and finish filling in the
168 * denode. Then return the address of the found denode.
169 */
170 if (ldep->de_Attributes & ATTR_DIRECTORY) {
171 /*
172 * Since DOS directory entries that describe directories
173 * have 0 in the filesize field, we take this opportunity
174 * to find out the length of the directory and plug it into
175 * the denode structure.
176 */
177 u_long size;
178
179 if (ldep->de_StartCluster != MSDOSFSROOT) {
180 error = pcbmap(ldep, CLUST_END, 0, &size, 0);
181 if (error == E2BIG) {
182 ldep->de_FileSize = de_cn2off(pmp, size);
183 error = 0;
184 } else
185 printf("deget(): pcbmap returned %d\n", error);
186 }
187 }
188 *depp = ldep;
189 return (0);
190 }
191
192 /*
193 * Truncate the file described by dep to the length specified by length.
194 */
195 int
detrunc(struct denode * dep,u_long length,int flags,struct kauth_cred * cred)196 detrunc(struct denode *dep, u_long length, int flags, struct kauth_cred *cred)
197 {
198 int error;
199 int allerror = 0;
200 u_long eofentry;
201 u_long chaintofree = 0;
202 daddr_t bn, lastblock;
203 int boff;
204 int isadir = dep->de_Attributes & ATTR_DIRECTORY;
205 struct buf *bp;
206 struct msdosfsmount *pmp = dep->de_pmp;
207
208 #ifdef MSDOSFS_DEBUG
209 printf("detrunc(): file %s, length %lu, flags %x\n", dep->de_Name, length, flags);
210 #endif
211
212 /*
213 * Disallow attempts to truncate the root directory since it is of
214 * fixed size. That's just the way dos filesystems are. We use
215 * the VROOT bit in the vnode because checking for the directory
216 * bit and a startcluster of 0 in the denode is not adequate to
217 * recognize the root directory at this point in a file or
218 * directory's life.
219 */
220 if (dep->de_vnode != NULL && !FAT32(pmp)) {
221 printf("detrunc(): can't truncate root directory, clust %ld, offset %ld\n",
222 dep->de_dirclust, dep->de_diroffset);
223 return (EINVAL);
224 }
225
226 if (dep->de_FileSize < length)
227 return (deextend(dep, length, cred));
228 lastblock = de_clcount(pmp, length) - 1;
229
230 /*
231 * If the desired length is 0 then remember the starting cluster of
232 * the file and set the StartCluster field in the directory entry
233 * to 0. If the desired length is not zero, then get the number of
234 * the last cluster in the shortened file. Then get the number of
235 * the first cluster in the part of the file that is to be freed.
236 * Then set the next cluster pointer in the last cluster of the
237 * file to CLUST_EOFE.
238 */
239 if (length == 0) {
240 chaintofree = dep->de_StartCluster;
241 dep->de_StartCluster = 0;
242 eofentry = ~0;
243 } else {
244 error = pcbmap(dep, lastblock, 0, &eofentry, 0);
245 if (error) {
246 #ifdef MSDOSFS_DEBUG
247 printf("detrunc(): pcbmap fails %d\n", error);
248 #endif
249 return (error);
250 }
251 }
252
253 /*
254 * If the new length is not a multiple of the cluster size then we
255 * must zero the tail end of the new last cluster in case it
256 * becomes part of the file again because of a seek.
257 */
258 if ((boff = length & pmp->pm_crbomask) != 0) {
259 if (isadir) {
260 bn = cntobn(pmp, eofentry);
261 error = bread(pmp->pm_devvp, de_bn2kb(pmp, bn),
262 pmp->pm_bpcluster, B_MODIFY, &bp);
263 if (error) {
264 #ifdef MSDOSFS_DEBUG
265 printf("detrunc(): bread fails %d\n", error);
266 #endif
267 return (error);
268 }
269 memset((char *)bp->b_data + boff, 0,
270 pmp->pm_bpcluster - boff);
271 if (flags & IO_SYNC)
272 bwrite(bp);
273 else
274 bdwrite(bp);
275 }
276 }
277
278 /*
279 * Write out the updated directory entry. Even if the update fails
280 * we free the trailing clusters.
281 */
282 dep->de_FileSize = length;
283 if (!isadir)
284 dep->de_flag |= DE_UPDATE|DE_MODIFIED;
285 #ifdef MSDOSFS_DEBUG
286 printf("detrunc(): allerror %d, eofentry %lu\n",
287 allerror, eofentry);
288 #endif
289
290 /*
291 * If we need to break the cluster chain for the file then do it
292 * now.
293 */
294 if (eofentry != (u_long)~0) {
295 error = fatentry(FAT_GET_AND_SET, pmp, eofentry,
296 &chaintofree, CLUST_EOFE);
297 if (error) {
298 #ifdef MSDOSFS_DEBUG
299 printf("detrunc(): fatentry errors %d\n", error);
300 #endif
301 return (error);
302 }
303 }
304
305 /*
306 * Now free the clusters removed from the file because of the
307 * truncation.
308 */
309 if (chaintofree != 0 && !MSDOSFSEOF(chaintofree, pmp->pm_fatmask))
310 freeclusterchain(pmp, chaintofree);
311
312 return (allerror);
313 }
314
315 /*
316 * Extend the file described by dep to length specified by length.
317 */
318 int
deextend(struct denode * dep,u_long length,struct kauth_cred * cred)319 deextend(struct denode *dep, u_long length, struct kauth_cred *cred)
320 {
321 struct msdosfsmount *pmp = dep->de_pmp;
322 u_long count;
323 int error;
324
325 /*
326 * The root of a DOS filesystem cannot be extended.
327 */
328 if (dep->de_vnode != NULL && !FAT32(pmp))
329 return EINVAL;
330
331 /*
332 * Directories cannot be extended.
333 */
334 if (dep->de_Attributes & ATTR_DIRECTORY)
335 return EISDIR;
336
337 if (length <= dep->de_FileSize)
338 return E2BIG;
339
340 /*
341 * Compute the number of clusters to allocate.
342 */
343 count = de_clcount(pmp, length) - de_clcount(pmp, dep->de_FileSize);
344 if (count > 0) {
345 if (count > pmp->pm_freeclustercount)
346 return (ENOSPC);
347 error = extendfile(dep, count, NULL, NULL, DE_CLEAR);
348 if (error) {
349 /* truncate the added clusters away again */
350 (void) detrunc(dep, dep->de_FileSize, 0, cred);
351 return (error);
352 }
353 }
354
355 /*
356 * Zero extend file range; ubc_zerorange() uses ubc_alloc() and a
357 * memset(); we set the write size so ubc won't read in file data that
358 * is zero'd later.
359 */
360 dep->de_FileSize = length;
361 dep->de_flag |= DE_UPDATE|DE_MODIFIED;
362 return 0;
363 }
364