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 <stdio.h> 58 #include <string.h> 59 #include <strings.h> 60 61 #include "ffs/buf.h" 62 63 #include <fs/msdosfs/bpb.h> 64 #include "msdos/direntry.h" 65 #include <fs/msdosfs/denode.h> 66 #include <fs/msdosfs/fat.h> 67 #include <fs/msdosfs/msdosfsmount.h> 68 69 #include "makefs.h" 70 #include "msdos.h" 71 72 #define FULL_RUN ((u_int)0xffffffff) 73 #define SYNCHRONOUS_WRITES(pmp) 1 74 75 static int chainalloc(struct msdosfsmount *pmp, u_long start, 76 u_long count, u_long fillwith, u_long *retcluster, 77 u_long *got); 78 static int chainlength(struct msdosfsmount *pmp, u_long start, 79 u_long count); 80 static void fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, 81 u_long *sizep, u_long *bop); 82 static int fatchain(struct msdosfsmount *pmp, u_long start, u_long count, 83 u_long fillwith); 84 static void fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, 85 u_long *fsrcnp); 86 static void updatefats(struct msdosfsmount *pmp, struct buf *bp, 87 u_long fatbn); 88 static __inline void 89 usemap_alloc(struct msdosfsmount *pmp, u_long cn); 90 static __inline void 91 usemap_free(struct msdosfsmount *pmp, u_long cn); 92 static int clusteralloc1(struct msdosfsmount *pmp, u_long start, 93 u_long count, u_long fillwith, u_long *retcluster, 94 u_long *got); 95 96 static void 97 fatblock(struct msdosfsmount *pmp, u_long ofs, u_long *bnp, u_long *sizep, 98 u_long *bop) 99 { 100 u_long bn, size; 101 102 bn = ofs / pmp->pm_fatblocksize * pmp->pm_fatblocksec; 103 size = MIN(pmp->pm_fatblocksec, pmp->pm_FATsecs - bn) 104 * DEV_BSIZE; 105 bn += pmp->pm_fatblk + pmp->pm_curfat * pmp->pm_FATsecs; 106 107 if (bnp) 108 *bnp = bn; 109 if (sizep) 110 *sizep = size; 111 if (bop) 112 *bop = ofs % pmp->pm_fatblocksize; 113 } 114 115 /* 116 * Map the logical cluster number of a file into a physical disk sector 117 * that is filesystem relative. 118 * 119 * dep - address of denode representing the file of interest 120 * findcn - file relative cluster whose filesystem relative cluster number 121 * and/or block number are/is to be found 122 * bnp - address of where to place the filesystem relative block number. 123 * If this pointer is null then don't return this quantity. 124 * cnp - address of where to place the filesystem relative cluster number. 125 * If this pointer is null then don't return this quantity. 126 * sp - pointer to returned block size 127 * 128 * NOTE: Either bnp or cnp must be non-null. 129 * This function has one side effect. If the requested file relative cluster 130 * is beyond the end of file, then the actual number of clusters in the file 131 * is returned in *cnp. This is useful for determining how long a directory is. 132 * If cnp is null, nothing is returned. 133 */ 134 int 135 pcbmap(struct denode *dep, u_long findcn, daddr_t *bnp, u_long *cnp, int *sp) 136 { 137 int error; 138 u_long i; 139 u_long cn; 140 u_long prevcn = 0; /* XXX: prevcn could be used unititialized */ 141 u_long byteoffset; 142 u_long bn; 143 u_long bo; 144 struct buf *bp = NULL; 145 u_long bp_bn = -1; 146 struct msdosfsmount *pmp = dep->de_pmp; 147 u_long bsize; 148 149 assert(bnp != NULL || cnp != NULL || sp != NULL); 150 151 cn = dep->de_StartCluster; 152 /* 153 * The "file" that makes up the root directory is contiguous, 154 * permanently allocated, of fixed size, and is not made up of 155 * clusters. If the cluster number is beyond the end of the root 156 * directory, then return the number of clusters in the file. 157 */ 158 if (cn == MSDOSFSROOT) { 159 if (dep->de_Attributes & ATTR_DIRECTORY) { 160 if (de_cn2off(pmp, findcn) >= dep->de_FileSize) { 161 if (cnp) 162 *cnp = de_bn2cn(pmp, pmp->pm_rootdirsize); 163 return (E2BIG); 164 } 165 if (bnp) 166 *bnp = pmp->pm_rootdirblk + de_cn2bn(pmp, findcn); 167 if (cnp) 168 *cnp = MSDOSFSROOT; 169 if (sp) 170 *sp = MIN(pmp->pm_bpcluster, 171 dep->de_FileSize - de_cn2off(pmp, findcn)); 172 return (0); 173 } else { /* just an empty file */ 174 if (cnp) 175 *cnp = 0; 176 return (E2BIG); 177 } 178 } 179 180 /* 181 * All other files do I/O in cluster sized blocks 182 */ 183 if (sp) 184 *sp = pmp->pm_bpcluster; 185 186 /* 187 * Rummage around in the FAT cache, maybe we can avoid tromping 188 * through every FAT entry for the file. And, keep track of how far 189 * off the cache was from where we wanted to be. 190 */ 191 i = 0; 192 fc_lookup(dep, findcn, &i, &cn); 193 194 /* 195 * Handle all other files or directories the normal way. 196 */ 197 for (; i < findcn; i++) { 198 /* 199 * Stop with all reserved clusters, not just with EOF. 200 */ 201 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 202 goto hiteof; 203 byteoffset = FATOFS(pmp, cn); 204 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 205 if (bn != bp_bn) { 206 if (bp) 207 brelse(bp); 208 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 209 if (error) { 210 brelse(bp); 211 return (error); 212 } 213 bp_bn = bn; 214 } 215 prevcn = cn; 216 if (bo >= bsize) { 217 if (bp) 218 brelse(bp); 219 return (EIO); 220 } 221 if (FAT32(pmp)) 222 cn = getulong(bp->b_data + bo); 223 else 224 cn = getushort(bp->b_data + bo); 225 if (FAT12(pmp) && (prevcn & 1)) 226 cn >>= 4; 227 cn &= pmp->pm_fatmask; 228 229 /* 230 * Force the special cluster numbers 231 * to be the same for all cluster sizes 232 * to let the rest of msdosfs handle 233 * all cases the same. 234 */ 235 if ((cn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 236 cn |= ~pmp->pm_fatmask; 237 } 238 239 if (!MSDOSFSEOF(pmp, cn)) { 240 if (bp) 241 brelse(bp); 242 if (bnp) 243 *bnp = cntobn(pmp, cn); 244 if (cnp) 245 *cnp = cn; 246 fc_setcache(dep, FC_LASTMAP, i, cn); 247 return (0); 248 } 249 250 hiteof:; 251 if (cnp) 252 *cnp = i; 253 if (bp) 254 brelse(bp); 255 /* update last file cluster entry in the FAT cache */ 256 fc_setcache(dep, FC_LASTFC, i - 1, prevcn); 257 return (E2BIG); 258 } 259 260 /* 261 * Find the closest entry in the FAT cache to the cluster we are looking 262 * for. 263 */ 264 static void 265 fc_lookup(struct denode *dep, u_long findcn, u_long *frcnp, u_long *fsrcnp) 266 { 267 int i; 268 u_long cn; 269 struct fatcache *closest = NULL; 270 271 for (i = 0; i < FC_SIZE; i++) { 272 cn = dep->de_fc[i].fc_frcn; 273 if (cn != FCE_EMPTY && cn <= findcn) { 274 if (closest == NULL || cn > closest->fc_frcn) 275 closest = &dep->de_fc[i]; 276 } 277 } 278 if (closest) { 279 *frcnp = closest->fc_frcn; 280 *fsrcnp = closest->fc_fsrcn; 281 } 282 } 283 284 /* 285 * Purge the FAT cache in denode dep of all entries relating to file 286 * relative cluster frcn and beyond. 287 */ 288 void 289 fc_purge(struct denode *dep, u_int frcn) 290 { 291 int i; 292 struct fatcache *fcp; 293 294 fcp = dep->de_fc; 295 for (i = 0; i < FC_SIZE; i++, fcp++) { 296 if (fcp->fc_frcn >= frcn) 297 fcp->fc_frcn = FCE_EMPTY; 298 } 299 } 300 301 /* 302 * Update the FAT. 303 * If mirroring the FAT, update all copies, with the first copy as last. 304 * Else update only the current FAT (ignoring the others). 305 * 306 * pmp - msdosfsmount structure for filesystem to update 307 * bp - addr of modified FAT block 308 * fatbn - block number relative to begin of filesystem of the modified FAT block. 309 */ 310 static void 311 updatefats(struct msdosfsmount *pmp, struct buf *bp, u_long fatbn) 312 { 313 struct buf *bpn; 314 int cleanfat, i; 315 316 #ifdef MSDOSFS_DEBUG 317 printf("updatefats(pmp %p, bp %p, fatbn %lu)\n", pmp, bp, fatbn); 318 #endif 319 320 if (pmp->pm_flags & MSDOSFS_FATMIRROR) { 321 /* 322 * Now copy the block(s) of the modified FAT to the other copies of 323 * the FAT and write them out. This is faster than reading in the 324 * other FATs and then writing them back out. This could tie up 325 * the FAT for quite a while. Preventing others from accessing it. 326 * To prevent us from going after the FAT quite so much we use 327 * delayed writes, unless they specified "synchronous" when the 328 * filesystem was mounted. If synch is asked for then use 329 * bwrite()'s and really slow things down. 330 */ 331 if (fatbn != pmp->pm_fatblk || FAT12(pmp)) 332 cleanfat = 0; 333 else if (FAT16(pmp)) 334 cleanfat = 16; 335 else 336 cleanfat = 32; 337 for (i = 1; i < pmp->pm_FATs; i++) { 338 fatbn += pmp->pm_FATsecs; 339 /* getblk() never fails */ 340 bpn = getblk(pmp->pm_devvp, fatbn, bp->b_bcount, 341 0, 0, 0); 342 memcpy(bpn->b_data, bp->b_data, bp->b_bcount); 343 /* Force the clean bit on in the other copies. */ 344 if (cleanfat == 16) 345 ((uint8_t *)bpn->b_data)[3] |= 0x80; 346 else if (cleanfat == 32) 347 ((uint8_t *)bpn->b_data)[7] |= 0x08; 348 if (SYNCHRONOUS_WRITES(pmp)) 349 bwrite(bpn); 350 else 351 bdwrite(bpn); 352 } 353 } 354 355 /* 356 * Write out the first (or current) FAT last. 357 */ 358 if (SYNCHRONOUS_WRITES(pmp)) 359 bwrite(bp); 360 else 361 bdwrite(bp); 362 } 363 364 /* 365 * Updating entries in 12 bit FATs is a pain in the butt. 366 * 367 * The following picture shows where nibbles go when moving from a 12 bit 368 * cluster number into the appropriate bytes in the FAT. 369 * 370 * byte m byte m+1 byte m+2 371 * +----+----+ +----+----+ +----+----+ 372 * | 0 1 | | 2 3 | | 4 5 | FAT bytes 373 * +----+----+ +----+----+ +----+----+ 374 * 375 * +----+----+----+ +----+----+----+ 376 * | 3 0 1 | | 4 5 2 | 377 * +----+----+----+ +----+----+----+ 378 * cluster n cluster n+1 379 * 380 * Where n is even. m = n + (n >> 2) 381 * 382 */ 383 static __inline void 384 usemap_alloc(struct msdosfsmount *pmp, u_long cn) 385 { 386 387 assert(cn <= pmp->pm_maxcluster); 388 assert((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0); 389 assert((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 390 == 0); 391 assert(pmp->pm_freeclustercount > 0); 392 393 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 394 pmp->pm_freeclustercount--; 395 pmp->pm_flags |= MSDOSFS_FSIMOD; 396 } 397 398 static __inline void 399 usemap_free(struct msdosfsmount *pmp, u_long cn) 400 { 401 402 assert(cn <= pmp->pm_maxcluster); 403 assert((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0); 404 assert((pmp->pm_inusemap[cn / N_INUSEBITS] & (1 << (cn % N_INUSEBITS))) 405 != 0); 406 407 pmp->pm_freeclustercount++; 408 pmp->pm_flags |= MSDOSFS_FSIMOD; 409 pmp->pm_inusemap[cn / N_INUSEBITS] &= ~(1U << (cn % N_INUSEBITS)); 410 } 411 412 int 413 clusterfree(struct msdosfsmount *pmp, u_long cluster, u_long *oldcnp) 414 { 415 int error; 416 u_long oldcn; 417 418 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 419 if (error) 420 return (error); 421 /* 422 * If the cluster was successfully marked free, then update 423 * the count of free clusters, and turn off the "allocated" 424 * bit in the "in use" cluster bit map. 425 */ 426 usemap_free(pmp, cluster); 427 if (oldcnp) 428 *oldcnp = oldcn; 429 return (0); 430 } 431 432 /* 433 * Get or Set or 'Get and Set' the cluster'th entry in the FAT. 434 * 435 * function - whether to get or set a FAT entry 436 * pmp - address of the msdosfsmount structure for the filesystem 437 * whose FAT is to be manipulated. 438 * cn - which cluster is of interest 439 * oldcontents - address of a word that is to receive the contents of the 440 * cluster'th entry if this is a get function 441 * newcontents - the new value to be written into the cluster'th element of 442 * the FAT if this is a set function. 443 * 444 * This function can also be used to free a cluster by setting the FAT entry 445 * for a cluster to 0. 446 * 447 * All copies of the FAT are updated if this is a set function. NOTE: If 448 * fatentry() marks a cluster as free it does not update the inusemap in 449 * the msdosfsmount structure. This is left to the caller. 450 */ 451 int 452 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents, 453 u_long newcontents) 454 { 455 int error; 456 u_long readcn; 457 u_long bn, bo, bsize, byteoffset; 458 struct buf *bp; 459 460 #ifdef MSDOSFS_DEBUG 461 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 462 function, pmp, cn, oldcontents, newcontents); 463 #endif 464 465 #ifdef DIAGNOSTIC 466 /* 467 * Be sure they asked us to do something. 468 */ 469 if ((function & (FAT_SET | FAT_GET)) == 0) { 470 #ifdef MSDOSFS_DEBUG 471 printf("fatentry(): function code doesn't specify get or set\n"); 472 #endif 473 return (EINVAL); 474 } 475 476 /* 477 * If they asked us to return a cluster number but didn't tell us 478 * where to put it, give them an error. 479 */ 480 if ((function & FAT_GET) && oldcontents == NULL) { 481 #ifdef MSDOSFS_DEBUG 482 printf("fatentry(): get function with no place to put result\n"); 483 #endif 484 return (EINVAL); 485 } 486 #endif 487 488 /* 489 * Be sure the requested cluster is in the filesystem. 490 */ 491 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 492 return (EINVAL); 493 494 byteoffset = FATOFS(pmp, cn); 495 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 496 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 497 if (error) { 498 brelse(bp); 499 return (error); 500 } 501 502 if (function & FAT_GET) { 503 if (FAT32(pmp)) 504 readcn = getulong(bp->b_data + bo); 505 else 506 readcn = getushort(bp->b_data + bo); 507 if (FAT12(pmp) & (cn & 1)) 508 readcn >>= 4; 509 readcn &= pmp->pm_fatmask; 510 /* map reserved FAT entries to same values for all FATs */ 511 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 512 readcn |= ~pmp->pm_fatmask; 513 *oldcontents = readcn; 514 } 515 if (function & FAT_SET) { 516 switch (pmp->pm_fatmask) { 517 case FAT12_MASK: 518 readcn = getushort(bp->b_data + bo); 519 if (cn & 1) { 520 readcn &= 0x000f; 521 readcn |= newcontents << 4; 522 } else { 523 readcn &= 0xf000; 524 readcn |= newcontents & 0xfff; 525 } 526 putushort(bp->b_data + bo, readcn); 527 break; 528 case FAT16_MASK: 529 putushort(bp->b_data + bo, newcontents); 530 break; 531 case FAT32_MASK: 532 /* 533 * According to spec we have to retain the 534 * high order bits of the FAT entry. 535 */ 536 readcn = getulong(bp->b_data + bo); 537 readcn &= ~FAT32_MASK; 538 readcn |= newcontents & FAT32_MASK; 539 putulong(bp->b_data + bo, readcn); 540 break; 541 } 542 updatefats(pmp, bp, bn); 543 bp = NULL; 544 pmp->pm_fmod = 1; 545 } 546 if (bp) 547 brelse(bp); 548 return (0); 549 } 550 551 /* 552 * Update a contiguous cluster chain 553 * 554 * pmp - mount point 555 * start - first cluster of chain 556 * count - number of clusters in chain 557 * fillwith - what to write into FAT entry of last cluster 558 */ 559 static int 560 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith) 561 { 562 int error; 563 u_long bn, bo, bsize, byteoffset, readcn, newc; 564 struct buf *bp; 565 566 #ifdef MSDOSFS_DEBUG 567 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 568 pmp, start, count, fillwith); 569 #endif 570 /* 571 * Be sure the clusters are in the filesystem. 572 */ 573 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 574 return (EINVAL); 575 576 while (count > 0) { 577 byteoffset = FATOFS(pmp, start); 578 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 579 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 580 if (error) { 581 brelse(bp); 582 return (error); 583 } 584 while (count > 0) { 585 start++; 586 newc = --count > 0 ? start : fillwith; 587 switch (pmp->pm_fatmask) { 588 case FAT12_MASK: 589 readcn = getushort(bp->b_data + bo); 590 if (start & 1) { 591 readcn &= 0xf000; 592 readcn |= newc & 0xfff; 593 } else { 594 readcn &= 0x000f; 595 readcn |= newc << 4; 596 } 597 putushort(bp->b_data + bo, readcn); 598 bo++; 599 if (!(start & 1)) 600 bo++; 601 break; 602 case FAT16_MASK: 603 putushort(bp->b_data + bo, newc); 604 bo += 2; 605 break; 606 case FAT32_MASK: 607 readcn = getulong(bp->b_data + bo); 608 readcn &= ~pmp->pm_fatmask; 609 readcn |= newc & pmp->pm_fatmask; 610 putulong(bp->b_data + bo, readcn); 611 bo += 4; 612 break; 613 } 614 if (bo >= bsize) 615 break; 616 } 617 updatefats(pmp, bp, bn); 618 } 619 pmp->pm_fmod = 1; 620 return (0); 621 } 622 623 /* 624 * Check the length of a free cluster chain starting at start. 625 * 626 * pmp - mount point 627 * start - start of chain 628 * count - maximum interesting length 629 */ 630 static int 631 chainlength(struct msdosfsmount *pmp, u_long start, u_long count) 632 { 633 u_long idx, max_idx; 634 u_int map; 635 u_long len; 636 637 if (start > pmp->pm_maxcluster) 638 return (0); 639 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 640 idx = start / N_INUSEBITS; 641 start %= N_INUSEBITS; 642 map = pmp->pm_inusemap[idx]; 643 map &= ~((1 << start) - 1); 644 if (map) { 645 len = ffs(map) - 1 - start; 646 len = MIN(len, count); 647 if (start + len > pmp->pm_maxcluster) 648 len = pmp->pm_maxcluster - start + 1; 649 return (len); 650 } 651 len = N_INUSEBITS - start; 652 if (len >= count) { 653 len = count; 654 if (start + len > pmp->pm_maxcluster) 655 len = pmp->pm_maxcluster - start + 1; 656 return (len); 657 } 658 while (++idx <= max_idx) { 659 if (len >= count) 660 break; 661 map = pmp->pm_inusemap[idx]; 662 if (map) { 663 len += ffs(map) - 1; 664 break; 665 } 666 len += N_INUSEBITS; 667 } 668 len = MIN(len, count); 669 if (start + len > pmp->pm_maxcluster) 670 len = pmp->pm_maxcluster - start + 1; 671 return (len); 672 } 673 674 /* 675 * Allocate contigous free clusters. 676 * 677 * pmp - mount point. 678 * start - start of cluster chain. 679 * count - number of clusters to allocate. 680 * fillwith - put this value into the FAT entry for the 681 * last allocated cluster. 682 * retcluster - put the first allocated cluster's number here. 683 * got - how many clusters were actually allocated. 684 */ 685 static int 686 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count, 687 u_long fillwith, u_long *retcluster, u_long *got) 688 { 689 int error; 690 u_long cl, n; 691 692 assert((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0); 693 694 for (cl = start, n = count; n-- > 0;) 695 usemap_alloc(pmp, cl++); 696 pmp->pm_nxtfree = start + count; 697 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 698 pmp->pm_nxtfree = CLUST_FIRST; 699 pmp->pm_flags |= MSDOSFS_FSIMOD; 700 error = fatchain(pmp, start, count, fillwith); 701 if (error != 0) { 702 for (cl = start, n = count; n-- > 0;) 703 usemap_free(pmp, cl++); 704 return (error); 705 } 706 #ifdef MSDOSFS_DEBUG 707 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 708 start, count); 709 #endif 710 if (retcluster) 711 *retcluster = start; 712 if (got) 713 *got = count; 714 return (0); 715 } 716 717 /* 718 * Allocate contiguous free clusters. 719 * 720 * pmp - mount point. 721 * start - preferred start of cluster chain. 722 * count - number of clusters requested. 723 * fillwith - put this value into the FAT entry for the 724 * last allocated cluster. 725 * retcluster - put the first allocated cluster's number here. 726 * got - how many clusters were actually allocated. 727 */ 728 int 729 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 730 u_long fillwith, u_long *retcluster, u_long *got) 731 { 732 int error; 733 734 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 735 return (error); 736 } 737 738 static int 739 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 740 u_long fillwith, u_long *retcluster, u_long *got) 741 { 742 u_long idx; 743 u_long len, newst, foundl, cn, l; 744 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 745 u_int map; 746 747 MSDOSFS_DPRINTF(("clusteralloc(): find %lu clusters\n", count)); 748 749 if (start) { 750 if ((len = chainlength(pmp, start, count)) >= count) 751 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 752 } else 753 len = 0; 754 755 newst = pmp->pm_nxtfree; 756 foundl = 0; 757 758 for (cn = newst; cn <= pmp->pm_maxcluster;) { 759 idx = cn / N_INUSEBITS; 760 map = pmp->pm_inusemap[idx]; 761 map |= (1U << (cn % N_INUSEBITS)) - 1; 762 if (map != FULL_RUN) { 763 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 764 if ((l = chainlength(pmp, cn, count)) >= count) 765 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 766 if (l > foundl) { 767 foundcn = cn; 768 foundl = l; 769 } 770 cn += l + 1; 771 continue; 772 } 773 cn += N_INUSEBITS - cn % N_INUSEBITS; 774 } 775 for (cn = 0; cn < newst;) { 776 idx = cn / N_INUSEBITS; 777 map = pmp->pm_inusemap[idx]; 778 map |= (1U << (cn % N_INUSEBITS)) - 1; 779 if (map != FULL_RUN) { 780 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 781 if ((l = chainlength(pmp, cn, count)) >= count) 782 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 783 if (l > foundl) { 784 foundcn = cn; 785 foundl = l; 786 } 787 cn += l + 1; 788 continue; 789 } 790 cn += N_INUSEBITS - cn % N_INUSEBITS; 791 } 792 793 if (!foundl) 794 return (ENOSPC); 795 796 if (len) 797 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 798 else 799 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 800 } 801 802 803 /* 804 * Free a chain of clusters. 805 * 806 * pmp - address of the msdosfs mount structure for the filesystem 807 * containing the cluster chain to be freed. 808 * startcluster - number of the 1st cluster in the chain of clusters to be 809 * freed. 810 */ 811 int 812 freeclusterchain(struct msdosfsmount *pmp, u_long cluster) 813 { 814 int error; 815 struct buf *bp = NULL; 816 u_long bn, bo, bsize, byteoffset; 817 u_long readcn, lbn = -1; 818 819 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 820 byteoffset = FATOFS(pmp, cluster); 821 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 822 if (lbn != bn) { 823 if (bp) 824 updatefats(pmp, bp, lbn); 825 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 826 if (error) { 827 brelse(bp); 828 return (error); 829 } 830 lbn = bn; 831 } 832 usemap_free(pmp, cluster); 833 switch (pmp->pm_fatmask) { 834 case FAT12_MASK: 835 readcn = getushort(bp->b_data + bo); 836 if (cluster & 1) { 837 cluster = readcn >> 4; 838 readcn &= 0x000f; 839 readcn |= MSDOSFSFREE << 4; 840 } else { 841 cluster = readcn; 842 readcn &= 0xf000; 843 readcn |= MSDOSFSFREE & 0xfff; 844 } 845 putushort(bp->b_data + bo, readcn); 846 break; 847 case FAT16_MASK: 848 cluster = getushort(bp->b_data + bo); 849 putushort(bp->b_data + bo, MSDOSFSFREE); 850 break; 851 case FAT32_MASK: 852 cluster = getulong(bp->b_data + bo); 853 putulong(bp->b_data + bo, 854 (MSDOSFSFREE & FAT32_MASK) | (cluster & ~FAT32_MASK)); 855 break; 856 } 857 cluster &= pmp->pm_fatmask; 858 if ((cluster | ~pmp->pm_fatmask) >= CLUST_RSRVD) 859 cluster |= pmp->pm_fatmask; 860 } 861 if (bp) 862 updatefats(pmp, bp, bn); 863 return (0); 864 } 865 866 /* 867 * Read in FAT blocks looking for free clusters. For every free cluster 868 * found turn off its corresponding bit in the pm_inusemap. 869 */ 870 int 871 fillinusemap(struct msdosfsmount *pmp) 872 { 873 struct buf *bp; 874 u_long bn, bo, bsize, byteoffset, cn, readcn; 875 int error; 876 877 bp = NULL; 878 879 /* 880 * Mark all clusters in use, we mark the free ones in the FAT scan 881 * loop further down. 882 */ 883 for (cn = 0; cn < (pmp->pm_maxcluster + N_INUSEBITS) / N_INUSEBITS; cn++) 884 pmp->pm_inusemap[cn] = FULL_RUN; 885 886 /* 887 * Figure how many free clusters are in the filesystem by ripping 888 * through the FAT counting the number of entries whose content is 889 * zero. These represent free clusters. 890 */ 891 pmp->pm_freeclustercount = 0; 892 for (cn = 0; cn <= pmp->pm_maxcluster; cn++) { 893 byteoffset = FATOFS(pmp, cn); 894 bo = byteoffset % pmp->pm_fatblocksize; 895 if (bo == 0) { 896 /* Read new FAT block */ 897 if (bp != NULL) 898 brelse(bp); 899 fatblock(pmp, byteoffset, &bn, &bsize, NULL); 900 error = bread(pmp->pm_devvp, bn, bsize, NOCRED, &bp); 901 if (error != 0) 902 return (error); 903 } 904 if (FAT32(pmp)) 905 readcn = getulong(bp->b_data + bo); 906 else 907 readcn = getushort(bp->b_data + bo); 908 if (FAT12(pmp) && (cn & 1)) 909 readcn >>= 4; 910 readcn &= pmp->pm_fatmask; 911 912 /* 913 * Check if the FAT ID matches the BPB's media descriptor and 914 * all other bits are set to 1. 915 */ 916 if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) | 917 pmp->pm_bpb.bpbMedia)) { 918 #ifdef MSDOSFS_DEBUG 919 printf("mountmsdosfs(): Media descriptor in BPB" 920 "does not match FAT ID\n"); 921 #endif 922 brelse(bp); 923 return (EINVAL); 924 } else if (readcn == CLUST_FREE) 925 usemap_free(pmp, cn); 926 } 927 if (bp != NULL) 928 brelse(bp); 929 930 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster + 931 N_INUSEBITS) / N_INUSEBITS; cn++) 932 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 933 934 return (0); 935 } 936 937 /* 938 * Allocate a new cluster and chain it onto the end of the file. 939 * 940 * dep - the file to extend 941 * count - number of clusters to allocate 942 * bpp - where to return the address of the buf header for the first new 943 * file block 944 * ncp - where to put cluster number of the first newly allocated cluster 945 * If this pointer is 0, do not return the cluster number. 946 * flags - see fat.h 947 * 948 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 949 * the de_flag field of the denode and it does not change the de_FileSize 950 * field. This is left for the caller to do. 951 */ 952 int 953 extendfile(struct denode *dep, u_long count, struct buf **bpp, u_long *ncp, 954 int flags) 955 { 956 int error; 957 u_long frcn; 958 u_long cn, got; 959 struct msdosfsmount *pmp = dep->de_pmp; 960 struct buf *bp; 961 962 /* 963 * Don't try to extend the root directory 964 */ 965 if (dep->de_StartCluster == MSDOSFSROOT 966 && (dep->de_Attributes & ATTR_DIRECTORY)) { 967 #ifdef MSDOSFS_DEBUG 968 printf("extendfile(): attempt to extend root directory\n"); 969 #endif 970 return (ENOSPC); 971 } 972 973 /* 974 * If the "file's last cluster" cache entry is empty, and the file 975 * is not empty, then fill the cache entry by calling pcbmap(). 976 */ 977 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 978 dep->de_StartCluster != 0) { 979 error = pcbmap(dep, 0xffff, 0, &cn, 0); 980 /* we expect it to return E2BIG */ 981 if (error != E2BIG) 982 return (error); 983 } 984 985 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 986 dep->de_fc[FC_LASTFC].fc_frcn; 987 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 988 dep->de_fc[FC_LASTFC].fc_fsrcn; 989 while (count > 0) { 990 /* 991 * Allocate a new cluster chain and cat onto the end of the 992 * file. If the file is empty we make de_StartCluster point 993 * to the new block. Note that de_StartCluster being 0 is 994 * sufficient to be sure the file is empty since we exclude 995 * attempts to extend the root directory above, and the root 996 * dir is the only file with a startcluster of 0 that has 997 * blocks allocated (sort of). 998 */ 999 if (dep->de_StartCluster == 0) 1000 cn = 0; 1001 else 1002 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1003 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1004 if (error) 1005 return (error); 1006 1007 count -= got; 1008 1009 /* 1010 * Give them the filesystem relative cluster number if they want 1011 * it. 1012 */ 1013 if (ncp) { 1014 *ncp = cn; 1015 ncp = NULL; 1016 } 1017 1018 if (dep->de_StartCluster == 0) { 1019 dep->de_StartCluster = cn; 1020 frcn = 0; 1021 } else { 1022 error = fatentry(FAT_SET, pmp, 1023 dep->de_fc[FC_LASTFC].fc_fsrcn, 1024 0, cn); 1025 if (error) { 1026 clusterfree(pmp, cn, NULL); 1027 return (error); 1028 } 1029 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1030 } 1031 1032 /* 1033 * Update the "last cluster of the file" entry in the 1034 * denode's FAT cache. 1035 */ 1036 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1037 1038 if ((flags & DE_CLEAR) && 1039 (dep->de_Attributes & ATTR_DIRECTORY)) { 1040 while (got-- > 0) { 1041 bp = getblk(pmp->pm_devvp, 1042 cntobn(pmp, cn++), 1043 pmp->pm_bpcluster, 0, 0, 0); 1044 clrbuf(bp); 1045 if (bpp) { 1046 *bpp = bp; 1047 bpp = NULL; 1048 } else { 1049 bdwrite(bp); 1050 } 1051 } 1052 } 1053 } 1054 1055 return (0); 1056 } 1057