1 /* $FreeBSD$ */ 2 /* $NetBSD: msdosfs_fat.c,v 1.28 1997/11/17 15:36:49 ws Exp $ */ 3 4 /*- 5 * SPDX-License-Identifier: BSD-4-Clause 6 * 7 * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank. 8 * Copyright (C) 1994, 1995, 1997 TooLs GmbH. 9 * All rights reserved. 10 * Original code by Paul Popelka (paulp@uts.amdahl.com) (see below). 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by TooLs GmbH. 23 * 4. The name of TooLs GmbH may not be used to endorse or promote products 24 * derived from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY TOOLS GMBH ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL TOOLS GMBH BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 31 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 32 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 33 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 34 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 35 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 /*- 38 * Written by Paul Popelka (paulp@uts.amdahl.com) 39 * 40 * You can do anything you want with this software, just don't say you wrote 41 * it, and don't remove this notice. 42 * 43 * This software is provided "as is". 44 * 45 * The author supplies this software to be publicly redistributed on the 46 * understanding that the author is not responsible for the correct 47 * functioning of this software in any circumstances and is not liable for 48 * any damages caused by this software. 49 * 50 * October 1992 51 */ 52 53 #include <sys/param.h> 54 #include <sys/errno.h> 55 56 #include <assert.h> 57 #include <stdbool.h> 58 #include <stdio.h> 59 #include <string.h> 60 #include <strings.h> 61 62 #include <vfs/msdosfs/bpb.h> 63 #include "msdos/denode.h" 64 #include <vfs/msdosfs/fat.h> 65 #include <vfs/msdosfs/msdosfsmount.h> 66 67 #include "makefs.h" 68 #include "msdos.h" 69 70 #define FULL_RUN ((u_int)0xffffffff) 71 #define SYNCHRONOUS_WRITES(pmp) 1 72 73 static int chainalloc(struct msdosfsmount *pmp, u_long start, 74 u_long count, u_long fillwith, u_long *retcluster, 75 u_long *got); 76 static int chainlength(struct msdosfsmount *pmp, u_long start, 77 u_long count); 78 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 79 u_long *sizep, u_long *bop); 80 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 81 u_long fillwith); 82 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 83 u_long *fsrcnp); 84 static void updatefats(struct msdosfsmount *pmp, struct m_buf *bp, 85 u_long fatbn); 86 static __inline void 87 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 88 static __inline void 89 usemap_free(struct msdosfsmount *pmp, u_long cn); 90 static int clusteralloc1(struct msdosfsmount *pmp, u_long start, 91 u_long count, u_long fillwith, u_long *retcluster, 92 u_long *got); 93 94 static void 95 fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep, 96 u_long *bop) 97 { 98 u_long bn, size; 99 100 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 101 size = MIN(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 102 * DEV_BSIZE; 103 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 104 105 if (bnp) 106 *bnp = bn; 107 if (sizep) 108 *sizep = size; 109 if (bop) 110 *bop = ofs % pmp->pm_fatblocksize; 111 } 112 113 /* 114 * Map the logical cluster number of a file into a physical disk sector 115 * that is filesystem relative. 116 * 117 * dep - address of denode representing the file of interest 118 * findcn - file relative cluster whose filesystem relative cluster number 119 * and/or block number are/is to be found 120 * bnp - address of where to place the filesystem relative block number. 121 * If this pointer is null then don't return this quantity. 122 * cnp - address of where to place the filesystem relative cluster number. 123 * If this pointer is null then don't return this quantity. 124 * sp - pointer to returned block size 125 * 126 * NOTE: Either bnp or cnp must be non-null. 127 * This function has one side effect. If the requested file relative cluster 128 * is beyond the end of file, then the actual number of clusters in the file 129 * is returned in *cnp. This is useful for determining how long a directory is. 130 * If cnp is null, nothing is returned. 131 */ 132 int 133 pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp) 134 { 135 int error; 136 u_long i; 137 u_long cn; 138 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 139 u_long byteoffset; 140 u_long bn; 141 u_long bo; 142 struct m_buf *bp = NULL; 143 u_long bp_bn = -1; 144 struct msdosfsmount *pmp = dep->de_pmp; 145 u_long bsize; 146 147 assert(bnp != NULL || cnp != NULL || sp != NULL); 148 149 cn = dep->de_StartCluster; 150 /* 151 * The "file" that makes up the root directory is contiguous, 152 * permanently allocated, of fixed size, and is not made up of 153 * clusters. If the cluster number is beyond the end of the root 154 * directory, then return the number of clusters in the file. 155 */ 156 if (cn == MSDOSFSROOT) { 157 if (dep->de_Attributes & ATTR_DIRECTORY) { 158 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 159 if (cnp) 160 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 161 return (E2BIG); 162 } 163 if (bnp) 164 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 165 if (cnp) 166 *cnp = MSDOSFSROOT; 167 if (sp) 168 *sp = MIN(pmp->pm_bpcluster, 169 dep->de_FileSize - de_cn2off(pmp, findcn)); 170 return (0); 171 } else { /* just an empty file */ 172 if (cnp) 173 *cnp = 0; 174 return (E2BIG); 175 } 176 } 177 178 /* 179 * All other files do I/O in cluster sized blocks 180 */ 181 if (sp) 182 *sp = pmp->pm_bpcluster; 183 184 /* 185 * Rummage around in the FAT cache, maybe we can avoid tromping 186 * through every FAT entry for the file. And, keep track of how far 187 * off the cache was from where we wanted to be. 188 */ 189 i = 0; 190 fc_lookup(dep, findcn, &i, &cn); 191 192 /* 193 * Handle all other files or directories the normal way. 194 */ 195 for (; i < findcn; i++) { 196 /* 197 * Stop with all reserved clusters, not just with EOF. 198 */ 199 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 200 goto hiteof; 201 byteoffset = FATOFS(pmp, cn); 202 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 203 if (bn != bp_bn) { 204 if (bp) 205 brelse(bp); 206 error = bread((void *)pmp->pm_devvp, bn, bsize, 207 NOCRED, &bp); 208 if (error) { 209 brelse(bp); 210 return (error); 211 } 212 bp_bn = bn; 213 } 214 prevcn = cn; 215 if (bo >= bsize) { 216 if (bp) 217 brelse(bp); 218 return (EIO); 219 } 220 if (FAT32(pmp)) 221 cn = getulong(bp->b_data + bo); 222 else 223 cn = getushort(bp->b_data + bo); 224 if (FAT12(pmp) && (prevcn & 1)) 225 cn >>= 4; 226 cn &= pmp->pm_fatmask; 227 228 /* 229 * Force the special cluster numbers 230 * to be the same for all cluster sizes 231 * to let the rest of msdosfs handle 232 * all cases the same. 233 */ 234 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 235 cn |= ~pmp->pm_fatmask; 236 } 237 238 if (!MSDOSFSEOF(pmp, cn)) { 239 if (bp) 240 brelse(bp); 241 if (bnp) 242 *bnp = cntobn(pmp, cn); 243 if (cnp) 244 *cnp = cn; 245 fc_setcache(dep, FC_LASTMAP, i, cn); 246 return (0); 247 } 248 249 hiteof:; 250 if (cnp) 251 *cnp = i; 252 if (bp) 253 brelse(bp); 254 /* update last file cluster entry in the FAT cache */ 255 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 256 return (E2BIG); 257 } 258 259 /* 260 * Find the closest entry in the FAT cache to the cluster we are looking 261 * for. 262 */ 263 static void 264 fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp) 265 { 266 int i; 267 u_long cn; 268 struct fatcache *closest = NULL; 269 270 for (i = 0; i < FC_SIZE; i++) { 271 cn = dep->de_fc[i].fc_frcn; 272 if (cn != FCE_EMPTY && cn <= findcn) { 273 if (closest == NULL || cn > closest->fc_frcn) 274 closest = &dep->de_fc[i]; 275 } 276 } 277 if (closest) { 278 *frcnp = closest->fc_frcn; 279 *fsrcnp = closest->fc_fsrcn; 280 } 281 } 282 283 /* 284 * Purge the FAT cache in denode dep of all entries relating to file 285 * relative cluster frcn and beyond. 286 */ 287 void 288 fc_purge(struct denode *dep, u_int frcn) 289 { 290 int i; 291 struct fatcache *fcp; 292 293 fcp = dep->de_fc; 294 for (i = 0; i < FC_SIZE; i++, fcp++) { 295 if (fcp->fc_frcn >= frcn) 296 fcp->fc_frcn = FCE_EMPTY; 297 } 298 } 299 300 /* 301 * Update the FAT. 302 * If mirroring the FAT, update all copies, with the first copy as last. 303 * Else update only the current FAT (ignoring the others). 304 * 305 * pmp - msdosfsmount structure for filesystem to update 306 * bp - addr of modified FAT block 307 * fatbn - block number relative to begin of filesystem of the modified FAT block. 308 */ 309 static void 310 updatefats(struct msdosfsmount *pmp, struct m_buf *bp, u_long fatbn) 311 { 312 struct m_buf *bpn; 313 int cleanfat, i; 314 315 #ifdef MSDOSFS_DEBUG 316 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 317 #endif 318 319 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 320 /* 321 * Now copy the block(s) of the modified FAT to the other copies of 322 * the FAT and write them out. This is faster than reading in the 323 * other FATs and then writing them back out. This could tie up 324 * the FAT for quite a while. Preventing others from accessing it. 325 * To prevent us from going after the FAT quite so much we use 326 * delayed writes, unless they specified "synchronous" when the 327 * filesystem was mounted. If synch is asked for then use 328 * bwrite()'s and really slow things down. 329 */ 330 if (fatbn != pmp->pm_fatblk || FAT12(pmp)) 331 cleanfat = 0; 332 else if (FAT16(pmp)) 333 cleanfat = 16; 334 else 335 cleanfat = 32; 336 for (i = 1; i < pmp->pm_FATs; i++) { 337 fatbn += pmp->pm_FATsecs; 338 /* getblk() never fails */ 339 bpn = getblk((void *)pmp->pm_devvp, fatbn, 340 bp->b_bcount, 0, 0, 0); 341 memcpy(bpn->b_data, bp->b_data, bp->b_bcount); 342 /* Force the clean bit on in the other copies. */ 343 if (cleanfat == 16) 344 ((uint8_t *)bpn->b_data)[3] |= 0x80; 345 else if (cleanfat == 32) 346 ((uint8_t *)bpn->b_data)[7] |= 0x08; 347 if (SYNCHRONOUS_WRITES(pmp)) 348 bwrite(bpn); 349 else 350 bdwrite(bpn); 351 } 352 } 353 354 /* 355 * Write out the first (or current) FAT last. 356 */ 357 if (SYNCHRONOUS_WRITES(pmp)) 358 bwrite(bp); 359 else 360 bdwrite(bp); 361 } 362 363 /* 364 * Updating entries in 12 bit FATs is a pain in the butt. 365 * 366 * The following picture shows where nibbles go when moving from a 12 bit 367 * cluster number into the appropriate bytes in the FAT. 368 * 369 * byte m byte m+1 byte m+2 370 * +----+----+ +----+----+ +----+----+ 371 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 372 * +----+----+ +----+----+ +----+----+ 373 * 374 * +----+----+----+ +----+----+----+ 375 * | 3 0 1 | | 4 5 2 | 376 * +----+----+----+ +----+----+----+ 377 * cluster n cluster n+1 378 * 379 * Where n is even. m = n + (n >> 2) 380 * 381 */ 382 static __inline void 383 usemap_alloc(struct msdosfsmount *pmp, u_long cn) 384 { 385 386 assert(cn <= pmp->pm_maxcluster); 387 assert((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0); 388 assert((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 389 == 0); 390 assert(pmp->pm_freeclustercount > 0); 391 392 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 393 pmp->pm_freeclustercount--; 394 pmp->pm_flags |= MSDOSFS_FSIMOD; 395 } 396 397 static __inline void 398 usemap_free(struct msdosfsmount *pmp, u_long cn) 399 { 400 401 assert(cn <= pmp->pm_maxcluster); 402 assert((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0); 403 assert((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 404 != 0); 405 406 pmp->pm_freeclustercount++; 407 pmp->pm_flags |= MSDOSFS_FSIMOD; 408 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1U << (cn % N_INUSEBITS)); 409 } 410 411 void 412 clusterfree(struct msdosfsmount *pmp, u_long cluster) 413 { 414 int error; 415 u_long oldcn; 416 417 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 418 if (error != 0) 419 return; 420 /* 421 * If the cluster was successfully marked free, then update 422 * the count of free clusters, and turn off the "allocated" 423 * bit in the "in use" cluster bit map. 424 */ 425 usemap_free(pmp, cluster); 426 } 427 428 /* 429 * Get or Set or 'Get and Set' the cluster'th entry in the FAT. 430 * 431 * function - whether to get or set a FAT entry 432 * pmp - address of the msdosfsmount structure for the filesystem 433 * whose FAT is to be manipulated. 434 * cn - which cluster is of interest 435 * oldcontents - address of a word that is to receive the contents of the 436 * cluster'th entry if this is a get function 437 * newcontents - the new value to be written into the cluster'th element of 438 * the FAT if this is a set function. 439 * 440 * This function can also be used to free a cluster by setting the FAT entry 441 * for a cluster to 0. 442 * 443 * All copies of the FAT are updated if this is a set function. NOTE: If 444 * fatentry() marks a cluster as free it does not update the inusemap in 445 * the msdosfsmount structure. This is left to the caller. 446 */ 447 int 448 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents, 449 u_long newcontents) 450 { 451 int error; 452 u_long readcn; 453 u_long bn, bo, bsize, byteoffset; 454 struct m_buf *bp; 455 456 #ifdef MSDOSFS_DEBUG 457 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 458 function, pmp, cn, oldcontents, newcontents); 459 #endif 460 461 #ifdef DIAGNOSTIC 462 /* 463 * Be sure they asked us to do something. 464 */ 465 if ((function & (FAT_SET | FAT_GET)) == 0) { 466 #ifdef MSDOSFS_DEBUG 467 printf("fatentry(): function code doesn't specify get or set\n"); 468 #endif 469 return (EINVAL); 470 } 471 472 /* 473 * If they asked us to return a cluster number but didn't tell us 474 * where to put it, give them an error. 475 */ 476 if ((function & FAT_GET) && oldcontents == NULL) { 477 #ifdef MSDOSFS_DEBUG 478 printf("fatentry(): get function with no place to put result\n"); 479 #endif 480 return (EINVAL); 481 } 482 #endif 483 484 /* 485 * Be sure the requested cluster is in the filesystem. 486 */ 487 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 488 return (EINVAL); 489 490 byteoffset = FATOFS(pmp, cn); 491 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 492 error = bread((void *)pmp->pm_devvp, bn, bsize, NOCRED, &bp); 493 if (error) { 494 brelse(bp); 495 return (error); 496 } 497 498 if (function & FAT_GET) { 499 if (FAT32(pmp)) 500 readcn = getulong(bp->b_data + bo); 501 else 502 readcn = getushort(bp->b_data + bo); 503 if (FAT12(pmp) & (cn & 1)) 504 readcn >>= 4; 505 readcn &= pmp->pm_fatmask; 506 /* map reserved FAT entries to same values for all FATs */ 507 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 508 readcn |= ~pmp->pm_fatmask; 509 *oldcontents = readcn; 510 } 511 if (function & FAT_SET) { 512 switch (pmp->pm_fatmask) { 513 case FAT12_MASK: 514 readcn = getushort(bp->b_data + bo); 515 if (cn & 1) { 516 readcn &= 0x000f; 517 readcn |= newcontents << 4; 518 } else { 519 readcn &= 0xf000; 520 readcn |= newcontents & 0xfff; 521 } 522 putushort(bp->b_data + bo, readcn); 523 break; 524 case FAT16_MASK: 525 putushort(bp->b_data + bo, newcontents); 526 break; 527 case FAT32_MASK: 528 /* 529 * According to spec we have to retain the 530 * high order bits of the FAT entry. 531 */ 532 readcn = getulong(bp->b_data + bo); 533 readcn &= ~FAT32_MASK; 534 readcn |= newcontents & FAT32_MASK; 535 putulong(bp->b_data + bo, readcn); 536 break; 537 } 538 updatefats(pmp, bp, bn); 539 bp = NULL; 540 pmp->pm_fmod = 1; 541 } 542 if (bp) 543 brelse(bp); 544 return (0); 545 } 546 547 /* 548 * Update a contiguous cluster chain 549 * 550 * pmp - mount point 551 * start - first cluster of chain 552 * count - number of clusters in chain 553 * fillwith - what to write into FAT entry of last cluster 554 */ 555 static int 556 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith) 557 { 558 int error; 559 u_long bn, bo, bsize, byteoffset, readcn, newc; 560 struct m_buf *bp; 561 562 #ifdef MSDOSFS_DEBUG 563 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 564 pmp, start, count, fillwith); 565 #endif 566 /* 567 * Be sure the clusters are in the filesystem. 568 */ 569 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 570 return (EINVAL); 571 572 while (count > 0) { 573 byteoffset = FATOFS(pmp, start); 574 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 575 error = bread((void *)pmp->pm_devvp, bn, bsize, NOCRED, &bp); 576 if (error) { 577 brelse(bp); 578 return (error); 579 } 580 while (count > 0) { 581 start++; 582 newc = --count > 0 ? start : fillwith; 583 switch (pmp->pm_fatmask) { 584 case FAT12_MASK: 585 readcn = getushort(bp->b_data + bo); 586 if (start & 1) { 587 readcn &= 0xf000; 588 readcn |= newc & 0xfff; 589 } else { 590 readcn &= 0x000f; 591 readcn |= newc << 4; 592 } 593 putushort(bp->b_data + bo, readcn); 594 bo++; 595 if (!(start & 1)) 596 bo++; 597 break; 598 case FAT16_MASK: 599 putushort(bp->b_data + bo, newc); 600 bo += 2; 601 break; 602 case FAT32_MASK: 603 readcn = getulong(bp->b_data + bo); 604 readcn &= ~pmp->pm_fatmask; 605 readcn |= newc & pmp->pm_fatmask; 606 putulong(bp->b_data + bo, readcn); 607 bo += 4; 608 break; 609 } 610 if (bo >= bsize) 611 break; 612 } 613 updatefats(pmp, bp, bn); 614 } 615 pmp->pm_fmod = 1; 616 return (0); 617 } 618 619 /* 620 * Check the length of a free cluster chain starting at start. 621 * 622 * pmp - mount point 623 * start - start of chain 624 * count - maximum interesting length 625 */ 626 static int 627 chainlength(struct msdosfsmount *pmp, u_long start, u_long count) 628 { 629 u_long idx, max_idx; 630 u_int map; 631 u_long len; 632 633 if (start > pmp->pm_maxcluster) 634 return (0); 635 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 636 idx = start / N_INUSEBITS; 637 start %= N_INUSEBITS; 638 map = pmp->pm_inusemap[idx]; 639 map &= ~((1 << start) - 1); 640 if (map) { 641 len = ffs(map) - 1 - start; 642 len = MIN(len, count); 643 if (start + len > pmp->pm_maxcluster) 644 len = pmp->pm_maxcluster - start + 1; 645 return (len); 646 } 647 len = N_INUSEBITS - start; 648 if (len >= count) { 649 len = count; 650 if (start + len > pmp->pm_maxcluster) 651 len = pmp->pm_maxcluster - start + 1; 652 return (len); 653 } 654 while (++idx <= max_idx) { 655 if (len >= count) 656 break; 657 map = pmp->pm_inusemap[idx]; 658 if (map) { 659 len += ffs(map) - 1; 660 break; 661 } 662 len += N_INUSEBITS; 663 } 664 len = MIN(len, count); 665 if (start + len > pmp->pm_maxcluster) 666 len = pmp->pm_maxcluster - start + 1; 667 return (len); 668 } 669 670 /* 671 * Allocate contigous free clusters. 672 * 673 * pmp - mount point. 674 * start - start of cluster chain. 675 * count - number of clusters to allocate. 676 * fillwith - put this value into the FAT entry for the 677 * last allocated cluster. 678 * retcluster - put the first allocated cluster's number here. 679 * got - how many clusters were actually allocated. 680 */ 681 static int 682 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count, 683 u_long fillwith, u_long *retcluster, u_long *got) 684 { 685 int error; 686 u_long cl, n; 687 688 assert((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0); 689 690 for (cl = start, n = count; n-- > 0;) 691 usemap_alloc(pmp, cl++); 692 pmp->pm_nxtfree = start + count; 693 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 694 pmp->pm_nxtfree = CLUST_FIRST; 695 pmp->pm_flags |= MSDOSFS_FSIMOD; 696 error = fatchain(pmp, start, count, fillwith); 697 if (error != 0) { 698 for (cl = start, n = count; n-- > 0;) 699 usemap_free(pmp, cl++); 700 return (error); 701 } 702 #ifdef MSDOSFS_DEBUG 703 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 704 start, count); 705 #endif 706 if (retcluster) 707 *retcluster = start; 708 if (got) 709 *got = count; 710 return (0); 711 } 712 713 /* 714 * Allocate contiguous free clusters. 715 * 716 * pmp - mount point. 717 * start - preferred start of cluster chain. 718 * count - number of clusters requested. 719 * fillwith - put this value into the FAT entry for the 720 * last allocated cluster. 721 * retcluster - put the first allocated cluster's number here. 722 * got - how many clusters were actually allocated. 723 */ 724 int 725 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 726 u_long fillwith, u_long *retcluster, u_long *got) 727 { 728 int error; 729 730 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 731 return (error); 732 } 733 734 static int 735 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 736 u_long fillwith, u_long *retcluster, u_long *got) 737 { 738 u_long idx; 739 u_long len, newst, foundl, cn, l; 740 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 741 u_int map; 742 743 MSDOSFS_DPRINTF(("clusteralloc(): find %lu clusters\n", count)); 744 745 if (start) { 746 if ((len = chainlength(pmp, start, count)) >= count) 747 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 748 } else 749 len = 0; 750 751 newst = pmp->pm_nxtfree; 752 foundl = 0; 753 754 for (cn = newst; cn <= pmp->pm_maxcluster;) { 755 idx = cn / N_INUSEBITS; 756 map = pmp->pm_inusemap[idx]; 757 map |= (1U << (cn % N_INUSEBITS)) - 1; 758 if (map != FULL_RUN) { 759 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 760 if ((l = chainlength(pmp, cn, count)) >= count) 761 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 762 if (l > foundl) { 763 foundcn = cn; 764 foundl = l; 765 } 766 cn += l + 1; 767 continue; 768 } 769 cn += N_INUSEBITS - cn % N_INUSEBITS; 770 } 771 for (cn = 0; cn < newst;) { 772 idx = cn / N_INUSEBITS; 773 map = pmp->pm_inusemap[idx]; 774 map |= (1U << (cn % N_INUSEBITS)) - 1; 775 if (map != FULL_RUN) { 776 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 777 if ((l = chainlength(pmp, cn, count)) >= count) 778 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 779 if (l > foundl) { 780 foundcn = cn; 781 foundl = l; 782 } 783 cn += l + 1; 784 continue; 785 } 786 cn += N_INUSEBITS - cn % N_INUSEBITS; 787 } 788 789 if (!foundl) 790 return (ENOSPC); 791 792 if (len) 793 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 794 else 795 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 796 } 797 798 799 /* 800 * Free a chain of clusters. 801 * 802 * pmp - address of the msdosfs mount structure for the filesystem 803 * containing the cluster chain to be freed. 804 * startcluster - number of the 1st cluster in the chain of clusters to be 805 * freed. 806 */ 807 int 808 freeclusterchain(struct msdosfsmount *pmp, u_long cluster) 809 { 810 int error; 811 struct m_buf *bp = NULL; 812 u_long bn, bo, bsize, byteoffset; 813 u_long readcn, lbn = -1; 814 815 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 816 byteoffset = FATOFS(pmp, cluster); 817 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 818 if (lbn != bn) { 819 if (bp) 820 updatefats(pmp, bp, lbn); 821 error = bread((void *)pmp->pm_devvp, bn, bsize, 822 NOCRED, &bp); 823 if (error) { 824 brelse(bp); 825 return (error); 826 } 827 lbn = bn; 828 } 829 usemap_free(pmp, cluster); 830 switch (pmp->pm_fatmask) { 831 case FAT12_MASK: 832 readcn = getushort(bp->b_data + bo); 833 if (cluster & 1) { 834 cluster = readcn >> 4; 835 readcn &= 0x000f; 836 readcn |= MSDOSFSFREE << 4; 837 } else { 838 cluster = readcn; 839 readcn &= 0xf000; 840 readcn |= MSDOSFSFREE & 0xfff; 841 } 842 putushort(bp->b_data + bo, readcn); 843 break; 844 case FAT16_MASK: 845 cluster = getushort(bp->b_data + bo); 846 putushort(bp->b_data + bo, MSDOSFSFREE); 847 break; 848 case FAT32_MASK: 849 cluster = getulong(bp->b_data + bo); 850 putulong(bp->b_data + bo, 851 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 852 break; 853 } 854 cluster &= pmp->pm_fatmask; 855 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 856 cluster |= pmp->pm_fatmask; 857 } 858 if (bp) 859 updatefats(pmp, bp, bn); 860 return (0); 861 } 862 863 /* 864 * Read in FAT blocks looking for free clusters. For every free cluster 865 * found turn off its corresponding bit in the pm_inusemap. 866 */ 867 int 868 fillinusemap(struct msdosfsmount *pmp) 869 { 870 struct m_buf *bp; 871 u_long bn, bo, bsize, byteoffset, cn, readcn; 872 int error; 873 874 bp = NULL; 875 876 /* 877 * Mark all clusters in use, we mark the free ones in the FAT scan 878 * loop further down. 879 */ 880 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 881 pmp->pm_inusemap[cn] = FULL_RUN; 882 883 /* 884 * Figure how many free clusters are in the filesystem by ripping 885 * through the FAT counting the number of entries whose content is 886 * zero. These represent free clusters. 887 */ 888 pmp->pm_freeclustercount = 0; 889 for (cn = 0; cn <= pmp->pm_maxcluster; cn++) { 890 byteoffset = FATOFS(pmp, cn); 891 bo = byteoffset % pmp->pm_fatblocksize; 892 if (bo == 0) { 893 /* Read new FAT block */ 894 if (bp != NULL) 895 brelse(bp); 896 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 897 error = bread((void *)pmp->pm_devvp, bn, bsize, 898 NOCRED, &bp); 899 if (error != 0) 900 return (error); 901 } 902 if (FAT32(pmp)) 903 readcn = getulong(bp->b_data + bo); 904 else 905 readcn = getushort(bp->b_data + bo); 906 if (FAT12(pmp) && (cn & 1)) 907 readcn >>= 4; 908 readcn &= pmp->pm_fatmask; 909 910 /* 911 * Check if the FAT ID matches the BPB's media descriptor and 912 * all other bits are set to 1. 913 */ 914 if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) | 915 pmp->pm_bpb.bpbMedia)) { 916 #ifdef MSDOSFS_DEBUG 917 printf("mountmsdosfs(): Media descriptor in BPB" 918 "does not match FAT ID\n"); 919 #endif 920 brelse(bp); 921 return (EINVAL); 922 } else if (readcn == CLUST_FREE) 923 usemap_free(pmp, cn); 924 } 925 if (bp != NULL) 926 brelse(bp); 927 928 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster + 929 N_INUSEBITS) / N_INUSEBITS; cn++) 930 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 931 932 return (0); 933 } 934 935 /* 936 * Allocate a new cluster and chain it onto the end of the file. 937 * 938 * dep - the file to extend 939 * count - number of clusters to allocate 940 * bpp - where to return the address of the buf header for the first new 941 * file block 942 * ncp - where to put cluster number of the first newly allocated cluster 943 * If this pointer is 0, do not return the cluster number. 944 * flags - see fat.h 945 * 946 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 947 * the de_flag field of the denode and it does not change the de_FileSize 948 * field. This is left for the caller to do. 949 */ 950 int 951 m_extendfile(struct denode *dep, u_long count, struct m_buf **bpp, u_long *ncp, 952 int flags) 953 { 954 int error; 955 u_long frcn; 956 u_long cn, got; 957 struct msdosfsmount *pmp = dep->de_pmp; 958 struct m_buf *bp; 959 960 /* 961 * Don't try to extend the root directory 962 */ 963 if (dep->de_StartCluster == MSDOSFSROOT 964 && (dep->de_Attributes & ATTR_DIRECTORY)) { 965 #ifdef MSDOSFS_DEBUG 966 printf("extendfile(): attempt to extend root directory\n"); 967 #endif 968 return (ENOSPC); 969 } 970 971 /* 972 * If the "file's last cluster" cache entry is empty, and the file 973 * is not empty, then fill the cache entry by calling pcbmap(). 974 */ 975 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 976 dep->de_StartCluster != 0) { 977 error = pcbmap(dep, 0xffff, 0, &cn, 0); 978 /* we expect it to return E2BIG */ 979 if (error != E2BIG) 980 return (error); 981 } 982 983 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 984 dep->de_fc[FC_LASTFC].fc_frcn; 985 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 986 dep->de_fc[FC_LASTFC].fc_fsrcn; 987 while (count > 0) { 988 /* 989 * Allocate a new cluster chain and cat onto the end of the 990 * file. If the file is empty we make de_StartCluster point 991 * to the new block. Note that de_StartCluster being 0 is 992 * sufficient to be sure the file is empty since we exclude 993 * attempts to extend the root directory above, and the root 994 * dir is the only file with a startcluster of 0 that has 995 * blocks allocated (sort of). 996 */ 997 if (dep->de_StartCluster == 0) 998 cn = 0; 999 else 1000 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1001 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1002 if (error) 1003 return (error); 1004 1005 count -= got; 1006 1007 /* 1008 * Give them the filesystem relative cluster number if they want 1009 * it. 1010 */ 1011 if (ncp) { 1012 *ncp = cn; 1013 ncp = NULL; 1014 } 1015 1016 if (dep->de_StartCluster == 0) { 1017 dep->de_StartCluster = cn; 1018 frcn = 0; 1019 } else { 1020 error = fatentry(FAT_SET, pmp, 1021 dep->de_fc[FC_LASTFC].fc_fsrcn, 1022 0, cn); 1023 if (error) { 1024 clusterfree(pmp, cn); 1025 return (error); 1026 } 1027 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1028 } 1029 1030 /* 1031 * Update the "last cluster of the file" entry in the 1032 * denode's FAT cache. 1033 */ 1034 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1035 1036 if ((flags & DE_CLEAR) && 1037 (dep->de_Attributes & ATTR_DIRECTORY)) { 1038 while (got-- > 0) { 1039 bp = getblk((void *)pmp->pm_devvp, 1040 cntobn(pmp, cn++), 1041 pmp->pm_bpcluster, 0, 0, 0); 1042 clrbuf(bp); 1043 if (bpp) { 1044 *bpp = bp; 1045 bpp = NULL; 1046 } else { 1047 bdwrite(bp); 1048 } 1049 } 1050 } 1051 } 1052 1053 return (0); 1054 } 1055