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 #include <sys/param.h> 54 #include <sys/errno.h> 55 56 #include <stdbool.h> 57 #include <stdio.h> 58 #include <string.h> 59 #include <stdlib.h> 60 #include <util.h> 61 62 #include <fs/msdosfs/bpb.h> 63 #include "msdos/denode.h" 64 #include <fs/msdosfs/fat.h> 65 #include <fs/msdosfs/msdosfsmount.h> 66 67 #include "makefs.h" 68 #include "msdos.h" 69 70 71 /* 72 * If deget() succeeds it returns with the gotten denode locked(). 73 * 74 * pmp - address of msdosfsmount structure of the filesystem containing 75 * the denode of interest. The pm_dev field and the address of 76 * the msdosfsmount structure are used. 77 * dirclust - which cluster bp contains, if dirclust is 0 (root directory) 78 * diroffset is relative to the beginning of the root directory, 79 * otherwise it is cluster relative. 80 * diroffset - offset past begin of cluster of denode we want 81 * depp - returns the address of the gotten denode. 82 */ 83 int 84 deget(struct msdosfsmount *pmp, u_long dirclust, u_long diroffset, 85 int lkflags __unused, struct denode **depp) 86 { 87 int error; 88 uint64_t inode; 89 struct direntry *direntptr; 90 struct denode *ldep; 91 struct m_buf *bp; 92 93 MSDOSFS_DPRINTF(("deget(pmp %p, dirclust %lu, diroffset %lx, depp %p)\n", 94 pmp, dirclust, diroffset, depp)); 95 96 /* 97 * On FAT32 filesystems, root is a (more or less) normal 98 * directory 99 */ 100 if (FAT32(pmp) && dirclust == MSDOSFSROOT) 101 dirclust = pmp->pm_rootdirblk; 102 103 inode = (uint64_t)pmp->pm_bpcluster * dirclust + diroffset; 104 105 ldep = ecalloc(1, sizeof(*ldep)); 106 ldep->de_vnode = NULL; 107 ldep->de_flag = 0; 108 ldep->de_dirclust = dirclust; 109 ldep->de_diroffset = diroffset; 110 ldep->de_inode = inode; 111 ldep->de_pmp = pmp; 112 ldep->de_refcnt = 1; 113 fc_purge(ldep, 0); /* init the FAT cache for this denode */ 114 /* 115 * Copy the directory entry into the denode area of the vnode. 116 */ 117 if ((dirclust == MSDOSFSROOT 118 || (FAT32(pmp) && dirclust == pmp->pm_rootdirblk)) 119 && diroffset == MSDOSFSROOT_OFS) { 120 /* 121 * Directory entry for the root directory. There isn't one, 122 * so we manufacture one. We should probably rummage 123 * through the root directory and find a label entry (if it 124 * exists), and then use the time and date from that entry 125 * as the time and date for the root denode. 126 */ 127 ldep->de_vnode = (struct vnode *)-1; 128 129 ldep->de_Attributes = ATTR_DIRECTORY; 130 ldep->de_LowerCase = 0; 131 if (FAT32(pmp)) 132 ldep->de_StartCluster = pmp->pm_rootdirblk; 133 /* de_FileSize will be filled in further down */ 134 else { 135 ldep->de_StartCluster = MSDOSFSROOT; 136 ldep->de_FileSize = pmp->pm_rootdirsize * DEV_BSIZE; 137 } 138 /* 139 * fill in time and date so that dos2unixtime() doesn't 140 * spit up when called from msdosfs_getattr() with root 141 * denode 142 */ 143 ldep->de_CHun = 0; 144 ldep->de_CTime = 0x0000; /* 00:00:00 */ 145 ldep->de_CDate = (0 << DD_YEAR_SHIFT) | (1 << DD_MONTH_SHIFT) 146 | (1 << DD_DAY_SHIFT); 147 /* Jan 1, 1980 */ 148 ldep->de_ADate = ldep->de_CDate; 149 ldep->de_MTime = ldep->de_CTime; 150 ldep->de_MDate = ldep->de_CDate; 151 /* leave the other fields as garbage */ 152 } else { 153 error = m_readep(pmp, dirclust, diroffset, &bp, &direntptr); 154 if (error) { 155 ldep->de_Name[0] = SLOT_DELETED; 156 157 *depp = NULL; 158 return (error); 159 } 160 (void)DE_INTERNALIZE(ldep, direntptr); 161 brelse(bp); 162 } 163 164 /* 165 * Fill in a few fields of the vnode and finish filling in the 166 * denode. Then return the address of the found denode. 167 */ 168 if (ldep->de_Attributes & ATTR_DIRECTORY) { 169 /* 170 * Since DOS directory entries that describe directories 171 * have 0 in the filesize field, we take this opportunity 172 * to find out the length of the directory and plug it into 173 * the denode structure. 174 */ 175 u_long size; 176 177 /* 178 * XXX it sometimes happens that the "." entry has cluster 179 * number 0 when it shouldn't. Use the actual cluster number 180 * instead of what is written in directory entry. 181 */ 182 if (diroffset == 0 && ldep->de_StartCluster != dirclust) { 183 MSDOSFS_DPRINTF(("deget(): \".\" entry at clust %lu != %lu\n", 184 dirclust, ldep->de_StartCluster)); 185 186 ldep->de_StartCluster = dirclust; 187 } 188 189 if (ldep->de_StartCluster != MSDOSFSROOT) { 190 error = pcbmap(ldep, 0xffff, 0, &size, 0); 191 if (error == E2BIG) { 192 ldep->de_FileSize = de_cn2off(pmp, size); 193 error = 0; 194 } else { 195 MSDOSFS_DPRINTF(("deget(): pcbmap returned %d\n", 196 error)); 197 } 198 } 199 } 200 *depp = ldep; 201 return (0); 202 } 203 204 /* 205 * Truncate the file described by dep to the length specified by length. 206 */ 207 int 208 detrunc(struct denode *dep, u_long length, int flags, struct ucred *cred) 209 { 210 int error; 211 u_long eofentry; 212 u_long chaintofree; 213 daddr_t bn; 214 int boff; 215 int isadir = dep->de_Attributes & ATTR_DIRECTORY; 216 struct m_buf *bp; 217 struct msdosfsmount *pmp = dep->de_pmp; 218 219 MSDOSFS_DPRINTF(("detrunc(): file %s, length %lu, flags %x\n", 220 dep->de_Name, length, flags)); 221 222 /* 223 * Disallow attempts to truncate the root directory since it is of 224 * fixed size. That's just the way dos filesystems are. We use 225 * the VROOT bit in the vnode because checking for the directory 226 * bit and a startcluster of 0 in the denode is not adequate to 227 * recognize the root directory at this point in a file or 228 * directory's life. 229 */ 230 if (dep->de_vnode != NULL && !FAT32(pmp)) { 231 MSDOSFS_DPRINTF(("detrunc(): can't truncate root directory, " 232 "clust %ld, offset %ld\n", 233 dep->de_dirclust, dep->de_diroffset)); 234 235 return (EINVAL); 236 } 237 238 if (dep->de_FileSize < length) 239 return deextend(dep, length, cred); 240 241 /* 242 * If the desired length is 0 then remember the starting cluster of 243 * the file and set the StartCluster field in the directory entry 244 * to 0. If the desired length is not zero, then get the number of 245 * the last cluster in the shortened file. Then get the number of 246 * the first cluster in the part of the file that is to be freed. 247 * Then set the next cluster pointer in the last cluster of the 248 * file to CLUST_EOFE. 249 */ 250 if (length == 0) { 251 chaintofree = dep->de_StartCluster; 252 dep->de_StartCluster = 0; 253 eofentry = ~0ul; 254 } else { 255 error = pcbmap(dep, de_clcount(pmp, length) - 1, 0, 256 &eofentry, 0); 257 if (error) { 258 MSDOSFS_DPRINTF(("detrunc(): pcbmap fails %d\n", 259 error)); 260 return (error); 261 } 262 } 263 264 fc_purge(dep, de_clcount(pmp, length)); 265 266 /* 267 * If the new length is not a multiple of the cluster size then we 268 * must zero the tail end of the new last cluster in case it 269 * becomes part of the file again because of a seek. 270 */ 271 if ((boff = length & pmp->pm_crbomask) != 0) { 272 if (isadir) { 273 bn = cntobn(pmp, eofentry); 274 error = bread((void *)pmp->pm_devvp, bn, 275 pmp->pm_bpcluster, 0, &bp); 276 if (error) { 277 brelse(bp); 278 MSDOSFS_DPRINTF(("detrunc(): bread fails %d\n", 279 error)); 280 281 return (error); 282 } 283 memset(bp->b_data + boff, 0, pmp->pm_bpcluster - boff); 284 bwrite(bp); 285 } 286 } 287 288 /* 289 * Write out the updated directory entry. Even if the update fails 290 * we free the trailing clusters. 291 */ 292 dep->de_FileSize = length; 293 if (!isadir) 294 dep->de_flag |= DE_UPDATE|DE_MODIFIED; 295 MSDOSFS_DPRINTF(("detrunc(): eofentry %lu\n", eofentry)); 296 297 /* 298 * If we need to break the cluster chain for the file then do it 299 * now. 300 */ 301 if (eofentry != ~0ul) { 302 error = fatentry(FAT_GET_AND_SET, pmp, eofentry, 303 &chaintofree, CLUST_EOFE); 304 if (error) { 305 MSDOSFS_DPRINTF(("detrunc(): fatentry errors %d\n", 306 error)); 307 return (error); 308 } 309 fc_setcache(dep, FC_LASTFC, de_cluster(pmp, length - 1), 310 eofentry); 311 } 312 313 /* 314 * Now free the clusters removed from the file because of the 315 * truncation. 316 */ 317 if (chaintofree != 0 && !MSDOSFSEOF(pmp, chaintofree)) 318 freeclusterchain(pmp, chaintofree); 319 320 return (0); 321 } 322 323 /* 324 * Extend the file described by dep to length specified by length. 325 */ 326 int 327 deextend(struct denode *dep, u_long length, struct ucred *cred) 328 { 329 struct msdosfsmount *pmp = dep->de_pmp; 330 u_long count; 331 int error; 332 333 /* 334 * The root of a DOS filesystem cannot be extended. 335 */ 336 if (dep->de_vnode != NULL && !FAT32(pmp)) 337 return (EINVAL); 338 339 /* 340 * Directories cannot be extended. 341 */ 342 if (dep->de_Attributes & ATTR_DIRECTORY) 343 return (EISDIR); 344 345 if (length <= dep->de_FileSize) 346 return (E2BIG); 347 348 /* 349 * Compute the number of clusters to allocate. 350 */ 351 count = de_clcount(pmp, length) - de_clcount(pmp, dep->de_FileSize); 352 if (count > 0) { 353 if (count > pmp->pm_freeclustercount) 354 return (ENOSPC); 355 error = m_extendfile(dep, count, NULL, NULL, DE_CLEAR); 356 if (error) { 357 /* truncate the added clusters away again */ 358 (void) detrunc(dep, dep->de_FileSize, 0, cred); 359 return (error); 360 } 361 } 362 363 /* 364 * Zero extend file range; ubc_zerorange() uses ubc_alloc() and a 365 * memset(); we set the write size so ubc won't read in file data that 366 * is zero'd later. 367 */ 368 dep->de_FileSize = length; 369 dep->de_flag |= DE_UPDATE | DE_MODIFIED; 370 return 0; 371 } 372