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 */ 81int 82msdosfs_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 */ 196int 197msdosfs_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 */ 320int 321msdosfs_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