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 int 412 clusterfree(struct msdosfsmount *pmp, u_long cluster, u_long *oldcnp) 413 { 414 int error; 415 u_long oldcn; 416 417 error = fatentry(FAT_GET_AND_SET, pmp, cluster, &oldcn, MSDOSFSFREE); 418 if (error) 419 return (error); 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 if (oldcnp) 427 *oldcnp = oldcn; 428 return (0); 429 } 430 431 /* 432 * Get or Set or 'Get and Set' the cluster'th entry in the FAT. 433 * 434 * function - whether to get or set a FAT entry 435 * pmp - address of the msdosfsmount structure for the filesystem 436 * whose FAT is to be manipulated. 437 * cn - which cluster is of interest 438 * oldcontents - address of a word that is to receive the contents of the 439 * cluster'th entry if this is a get function 440 * newcontents - the new value to be written into the cluster'th element of 441 * the FAT if this is a set function. 442 * 443 * This function can also be used to free a cluster by setting the FAT entry 444 * for a cluster to 0. 445 * 446 * All copies of the FAT are updated if this is a set function. NOTE: If 447 * fatentry() marks a cluster as free it does not update the inusemap in 448 * the msdosfsmount structure. This is left to the caller. 449 */ 450 int 451 fatentry(int function, struct msdosfsmount *pmp, u_long cn, u_long *oldcontents, 452 u_long newcontents) 453 { 454 int error; 455 u_long readcn; 456 u_long bn, bo, bsize, byteoffset; 457 struct m_buf *bp; 458 459 #ifdef MSDOSFS_DEBUG 460 printf("fatentry(func %d, pmp %p, clust %lu, oldcon %p, newcon %lx)\n", 461 function, pmp, cn, oldcontents, newcontents); 462 #endif 463 464 #ifdef DIAGNOSTIC 465 /* 466 * Be sure they asked us to do something. 467 */ 468 if ((function & (FAT_SET | FAT_GET)) == 0) { 469 #ifdef MSDOSFS_DEBUG 470 printf("fatentry(): function code doesn't specify get or set\n"); 471 #endif 472 return (EINVAL); 473 } 474 475 /* 476 * If they asked us to return a cluster number but didn't tell us 477 * where to put it, give them an error. 478 */ 479 if ((function & FAT_GET) && oldcontents == NULL) { 480 #ifdef MSDOSFS_DEBUG 481 printf("fatentry(): get function with no place to put result\n"); 482 #endif 483 return (EINVAL); 484 } 485 #endif 486 487 /* 488 * Be sure the requested cluster is in the filesystem. 489 */ 490 if (cn < CLUST_FIRST || cn > pmp->pm_maxcluster) 491 return (EINVAL); 492 493 byteoffset = FATOFS(pmp, cn); 494 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 495 error = bread((void *)pmp->pm_devvp, bn, bsize, NOCRED, &bp); 496 if (error) { 497 brelse(bp); 498 return (error); 499 } 500 501 if (function & FAT_GET) { 502 if (FAT32(pmp)) 503 readcn = getulong(bp->b_data + bo); 504 else 505 readcn = getushort(bp->b_data + bo); 506 if (FAT12(pmp) & (cn & 1)) 507 readcn >>= 4; 508 readcn &= pmp->pm_fatmask; 509 /* map reserved FAT entries to same values for all FATs */ 510 if ((readcn | ~pmp->pm_fatmask) >= CLUST_RSRVD) 511 readcn |= ~pmp->pm_fatmask; 512 *oldcontents = readcn; 513 } 514 if (function & FAT_SET) { 515 switch (pmp->pm_fatmask) { 516 case FAT12_MASK: 517 readcn = getushort(bp->b_data + bo); 518 if (cn & 1) { 519 readcn &= 0x000f; 520 readcn |= newcontents << 4; 521 } else { 522 readcn &= 0xf000; 523 readcn |= newcontents & 0xfff; 524 } 525 putushort(bp->b_data + bo, readcn); 526 break; 527 case FAT16_MASK: 528 putushort(bp->b_data + bo, newcontents); 529 break; 530 case FAT32_MASK: 531 /* 532 * According to spec we have to retain the 533 * high order bits of the FAT entry. 534 */ 535 readcn = getulong(bp->b_data + bo); 536 readcn &= ~FAT32_MASK; 537 readcn |= newcontents & FAT32_MASK; 538 putulong(bp->b_data + bo, readcn); 539 break; 540 } 541 updatefats(pmp, bp, bn); 542 bp = NULL; 543 pmp->pm_fmod = 1; 544 } 545 if (bp) 546 brelse(bp); 547 return (0); 548 } 549 550 /* 551 * Update a contiguous cluster chain 552 * 553 * pmp - mount point 554 * start - first cluster of chain 555 * count - number of clusters in chain 556 * fillwith - what to write into FAT entry of last cluster 557 */ 558 static int 559 fatchain(struct msdosfsmount *pmp, u_long start, u_long count, u_long fillwith) 560 { 561 int error; 562 u_long bn, bo, bsize, byteoffset, readcn, newc; 563 struct m_buf *bp; 564 565 #ifdef MSDOSFS_DEBUG 566 printf("fatchain(pmp %p, start %lu, count %lu, fillwith %lx)\n", 567 pmp, start, count, fillwith); 568 #endif 569 /* 570 * Be sure the clusters are in the filesystem. 571 */ 572 if (start < CLUST_FIRST || start + count - 1 > pmp->pm_maxcluster) 573 return (EINVAL); 574 575 while (count > 0) { 576 byteoffset = FATOFS(pmp, start); 577 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 578 error = bread((void *)pmp->pm_devvp, bn, bsize, NOCRED, &bp); 579 if (error) { 580 brelse(bp); 581 return (error); 582 } 583 while (count > 0) { 584 start++; 585 newc = --count > 0 ? start : fillwith; 586 switch (pmp->pm_fatmask) { 587 case FAT12_MASK: 588 readcn = getushort(bp->b_data + bo); 589 if (start & 1) { 590 readcn &= 0xf000; 591 readcn |= newc & 0xfff; 592 } else { 593 readcn &= 0x000f; 594 readcn |= newc << 4; 595 } 596 putushort(bp->b_data + bo, readcn); 597 bo++; 598 if (!(start & 1)) 599 bo++; 600 break; 601 case FAT16_MASK: 602 putushort(bp->b_data + bo, newc); 603 bo += 2; 604 break; 605 case FAT32_MASK: 606 readcn = getulong(bp->b_data + bo); 607 readcn &= ~pmp->pm_fatmask; 608 readcn |= newc & pmp->pm_fatmask; 609 putulong(bp->b_data + bo, readcn); 610 bo += 4; 611 break; 612 } 613 if (bo >= bsize) 614 break; 615 } 616 updatefats(pmp, bp, bn); 617 } 618 pmp->pm_fmod = 1; 619 return (0); 620 } 621 622 /* 623 * Check the length of a free cluster chain starting at start. 624 * 625 * pmp - mount point 626 * start - start of chain 627 * count - maximum interesting length 628 */ 629 static int 630 chainlength(struct msdosfsmount *pmp, u_long start, u_long count) 631 { 632 u_long idx, max_idx; 633 u_int map; 634 u_long len; 635 636 if (start > pmp->pm_maxcluster) 637 return (0); 638 max_idx = pmp->pm_maxcluster / N_INUSEBITS; 639 idx = start / N_INUSEBITS; 640 start %= N_INUSEBITS; 641 map = pmp->pm_inusemap[idx]; 642 map &= ~((1 << start) - 1); 643 if (map) { 644 len = ffs(map) - 1 - start; 645 len = MIN(len, count); 646 if (start + len > pmp->pm_maxcluster) 647 len = pmp->pm_maxcluster - start + 1; 648 return (len); 649 } 650 len = N_INUSEBITS - start; 651 if (len >= count) { 652 len = count; 653 if (start + len > pmp->pm_maxcluster) 654 len = pmp->pm_maxcluster - start + 1; 655 return (len); 656 } 657 while (++idx <= max_idx) { 658 if (len >= count) 659 break; 660 map = pmp->pm_inusemap[idx]; 661 if (map) { 662 len += ffs(map) - 1; 663 break; 664 } 665 len += N_INUSEBITS; 666 } 667 len = MIN(len, count); 668 if (start + len > pmp->pm_maxcluster) 669 len = pmp->pm_maxcluster - start + 1; 670 return (len); 671 } 672 673 /* 674 * Allocate contigous free clusters. 675 * 676 * pmp - mount point. 677 * start - start of cluster chain. 678 * count - number of clusters to allocate. 679 * fillwith - put this value into the FAT entry for the 680 * last allocated cluster. 681 * retcluster - put the first allocated cluster's number here. 682 * got - how many clusters were actually allocated. 683 */ 684 static int 685 chainalloc(struct msdosfsmount *pmp, u_long start, u_long count, 686 u_long fillwith, u_long *retcluster, u_long *got) 687 { 688 int error; 689 u_long cl, n; 690 691 assert((pmp->pm_flags & MSDOSFSMNT_RONLY) == 0); 692 693 for (cl = start, n = count; n-- > 0;) 694 usemap_alloc(pmp, cl++); 695 pmp->pm_nxtfree = start + count; 696 if (pmp->pm_nxtfree > pmp->pm_maxcluster) 697 pmp->pm_nxtfree = CLUST_FIRST; 698 pmp->pm_flags |= MSDOSFS_FSIMOD; 699 error = fatchain(pmp, start, count, fillwith); 700 if (error != 0) { 701 for (cl = start, n = count; n-- > 0;) 702 usemap_free(pmp, cl++); 703 return (error); 704 } 705 #ifdef MSDOSFS_DEBUG 706 printf("clusteralloc(): allocated cluster chain at %lu (%lu clusters)\n", 707 start, count); 708 #endif 709 if (retcluster) 710 *retcluster = start; 711 if (got) 712 *got = count; 713 return (0); 714 } 715 716 /* 717 * Allocate contiguous free clusters. 718 * 719 * pmp - mount point. 720 * start - preferred start of cluster chain. 721 * count - number of clusters requested. 722 * fillwith - put this value into the FAT entry for the 723 * last allocated cluster. 724 * retcluster - put the first allocated cluster's number here. 725 * got - how many clusters were actually allocated. 726 */ 727 int 728 clusteralloc(struct msdosfsmount *pmp, u_long start, u_long count, 729 u_long fillwith, u_long *retcluster, u_long *got) 730 { 731 int error; 732 733 error = clusteralloc1(pmp, start, count, fillwith, retcluster, got); 734 return (error); 735 } 736 737 static int 738 clusteralloc1(struct msdosfsmount *pmp, u_long start, u_long count, 739 u_long fillwith, u_long *retcluster, u_long *got) 740 { 741 u_long idx; 742 u_long len, newst, foundl, cn, l; 743 u_long foundcn = 0; /* XXX: foundcn could be used unititialized */ 744 u_int map; 745 746 MSDOSFS_DPRINTF(("clusteralloc(): find %lu clusters\n", count)); 747 748 if (start) { 749 if ((len = chainlength(pmp, start, count)) >= count) 750 return (chainalloc(pmp, start, count, fillwith, retcluster, got)); 751 } else 752 len = 0; 753 754 newst = pmp->pm_nxtfree; 755 foundl = 0; 756 757 for (cn = newst; cn <= pmp->pm_maxcluster;) { 758 idx = cn / N_INUSEBITS; 759 map = pmp->pm_inusemap[idx]; 760 map |= (1U << (cn % N_INUSEBITS)) - 1; 761 if (map != FULL_RUN) { 762 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 763 if ((l = chainlength(pmp, cn, count)) >= count) 764 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 765 if (l > foundl) { 766 foundcn = cn; 767 foundl = l; 768 } 769 cn += l + 1; 770 continue; 771 } 772 cn += N_INUSEBITS - cn % N_INUSEBITS; 773 } 774 for (cn = 0; cn < newst;) { 775 idx = cn / N_INUSEBITS; 776 map = pmp->pm_inusemap[idx]; 777 map |= (1U << (cn % N_INUSEBITS)) - 1; 778 if (map != FULL_RUN) { 779 cn = idx * N_INUSEBITS + ffs(map ^ FULL_RUN) - 1; 780 if ((l = chainlength(pmp, cn, count)) >= count) 781 return (chainalloc(pmp, cn, count, fillwith, retcluster, got)); 782 if (l > foundl) { 783 foundcn = cn; 784 foundl = l; 785 } 786 cn += l + 1; 787 continue; 788 } 789 cn += N_INUSEBITS - cn % N_INUSEBITS; 790 } 791 792 if (!foundl) 793 return (ENOSPC); 794 795 if (len) 796 return (chainalloc(pmp, start, len, fillwith, retcluster, got)); 797 else 798 return (chainalloc(pmp, foundcn, foundl, fillwith, retcluster, got)); 799 } 800 801 802 /* 803 * Free a chain of clusters. 804 * 805 * pmp - address of the msdosfs mount structure for the filesystem 806 * containing the cluster chain to be freed. 807 * startcluster - number of the 1st cluster in the chain of clusters to be 808 * freed. 809 */ 810 int 811 freeclusterchain(struct msdosfsmount *pmp, u_long cluster) 812 { 813 int error; 814 struct m_buf *bp = NULL; 815 u_long bn, bo, bsize, byteoffset; 816 u_long readcn, lbn = -1; 817 818 while (cluster >= CLUST_FIRST && cluster <= pmp->pm_maxcluster) { 819 byteoffset = FATOFS(pmp, cluster); 820 fatblock(pmp, byteoffset, &bn, &bsize, &bo); 821 if (lbn != bn) { 822 if (bp) 823 updatefats(pmp, bp, lbn); 824 error = bread((void *)pmp->pm_devvp, bn, bsize, 825 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 m_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((void *)pmp->pm_devvp, bn, bsize, 901 NOCRED, &bp); 902 if (error != 0) 903 return (error); 904 } 905 if (FAT32(pmp)) 906 readcn = getulong(bp->b_data + bo); 907 else 908 readcn = getushort(bp->b_data + bo); 909 if (FAT12(pmp) && (cn & 1)) 910 readcn >>= 4; 911 readcn &= pmp->pm_fatmask; 912 913 /* 914 * Check if the FAT ID matches the BPB's media descriptor and 915 * all other bits are set to 1. 916 */ 917 if (cn == 0 && readcn != ((pmp->pm_fatmask & 0xffffff00) | 918 pmp->pm_bpb.bpbMedia)) { 919 #ifdef MSDOSFS_DEBUG 920 printf("mountmsdosfs(): Media descriptor in BPB" 921 "does not match FAT ID\n"); 922 #endif 923 brelse(bp); 924 return (EINVAL); 925 } else if (readcn == CLUST_FREE) 926 usemap_free(pmp, cn); 927 } 928 if (bp != NULL) 929 brelse(bp); 930 931 for (cn = pmp->pm_maxcluster + 1; cn < (pmp->pm_maxcluster + 932 N_INUSEBITS) / N_INUSEBITS; cn++) 933 pmp->pm_inusemap[cn / N_INUSEBITS] |= 1U << (cn % N_INUSEBITS); 934 935 return (0); 936 } 937 938 /* 939 * Allocate a new cluster and chain it onto the end of the file. 940 * 941 * dep - the file to extend 942 * count - number of clusters to allocate 943 * bpp - where to return the address of the buf header for the first new 944 * file block 945 * ncp - where to put cluster number of the first newly allocated cluster 946 * If this pointer is 0, do not return the cluster number. 947 * flags - see fat.h 948 * 949 * NOTE: This function is not responsible for turning on the DE_UPDATE bit of 950 * the de_flag field of the denode and it does not change the de_FileSize 951 * field. This is left for the caller to do. 952 */ 953 int 954 m_extendfile(struct denode *dep, u_long count, struct m_buf **bpp, u_long *ncp, 955 int flags) 956 { 957 int error; 958 u_long frcn; 959 u_long cn, got; 960 struct msdosfsmount *pmp = dep->de_pmp; 961 struct m_buf *bp; 962 963 /* 964 * Don't try to extend the root directory 965 */ 966 if (dep->de_StartCluster == MSDOSFSROOT 967 && (dep->de_Attributes & ATTR_DIRECTORY)) { 968 #ifdef MSDOSFS_DEBUG 969 printf("extendfile(): attempt to extend root directory\n"); 970 #endif 971 return (ENOSPC); 972 } 973 974 /* 975 * If the "file's last cluster" cache entry is empty, and the file 976 * is not empty, then fill the cache entry by calling pcbmap(). 977 */ 978 if (dep->de_fc[FC_LASTFC].fc_frcn == FCE_EMPTY && 979 dep->de_StartCluster != 0) { 980 error = pcbmap(dep, 0xffff, 0, &cn, 0); 981 /* we expect it to return E2BIG */ 982 if (error != E2BIG) 983 return (error); 984 } 985 986 dep->de_fc[FC_NEXTTOLASTFC].fc_frcn = 987 dep->de_fc[FC_LASTFC].fc_frcn; 988 dep->de_fc[FC_NEXTTOLASTFC].fc_fsrcn = 989 dep->de_fc[FC_LASTFC].fc_fsrcn; 990 while (count > 0) { 991 /* 992 * Allocate a new cluster chain and cat onto the end of the 993 * file. If the file is empty we make de_StartCluster point 994 * to the new block. Note that de_StartCluster being 0 is 995 * sufficient to be sure the file is empty since we exclude 996 * attempts to extend the root directory above, and the root 997 * dir is the only file with a startcluster of 0 that has 998 * blocks allocated (sort of). 999 */ 1000 if (dep->de_StartCluster == 0) 1001 cn = 0; 1002 else 1003 cn = dep->de_fc[FC_LASTFC].fc_fsrcn + 1; 1004 error = clusteralloc(pmp, cn, count, CLUST_EOFE, &cn, &got); 1005 if (error) 1006 return (error); 1007 1008 count -= got; 1009 1010 /* 1011 * Give them the filesystem relative cluster number if they want 1012 * it. 1013 */ 1014 if (ncp) { 1015 *ncp = cn; 1016 ncp = NULL; 1017 } 1018 1019 if (dep->de_StartCluster == 0) { 1020 dep->de_StartCluster = cn; 1021 frcn = 0; 1022 } else { 1023 error = fatentry(FAT_SET, pmp, 1024 dep->de_fc[FC_LASTFC].fc_fsrcn, 1025 0, cn); 1026 if (error) { 1027 clusterfree(pmp, cn, NULL); 1028 return (error); 1029 } 1030 frcn = dep->de_fc[FC_LASTFC].fc_frcn + 1; 1031 } 1032 1033 /* 1034 * Update the "last cluster of the file" entry in the 1035 * denode's FAT cache. 1036 */ 1037 fc_setcache(dep, FC_LASTFC, frcn + got - 1, cn + got - 1); 1038 1039 if ((flags & DE_CLEAR) && 1040 (dep->de_Attributes & ATTR_DIRECTORY)) { 1041 while (got-- > 0) { 1042 bp = getblk((void *)pmp->pm_devvp, 1043 cntobn(pmp, cn++), 1044 pmp->pm_bpcluster, 0, 0, 0); 1045 clrbuf(bp); 1046 if (bpp) { 1047 *bpp = bp; 1048 bpp = NULL; 1049 } else { 1050 bdwrite(bp); 1051 } 1052 } 1053 } 1054 } 1055 1056 return (0); 1057 } 1058