livefiles_hfs_plugin/lf_hfs_readwrite_ops.c

   1 //
   2 //  lf_hfs_readwrite_ops.c
   3 //  livefiles_hfs
   4 //
   5 //  Created by Yakov Ben Zaken on 22/03/2018.
   6 //
   7
   8 #include "lf_hfs_readwrite_ops.h"
   9 #include "lf_hfs_rangelist.h"
  10 #include "lf_hfs_vfsutils.h"
  11 #include "lf_hfs_file_extent_mapping.h"
  12 #include "lf_hfs_vfsops.h"
  13 #include "lf_hfs_cnode.h"
  14 #include "lf_hfs_file_mgr_internal.h"
  15 #include "lf_hfs_utils.h"
  16 #include "lf_hfs_vnops.h"
  17 #include "lf_hfs_raw_read_write.h"
  18
  19 #include <assert.h>
  20
  21 static int  do_hfs_truncate(struct vnode *vp, off_t length, int flags, int skip);
  22
  23 static int
  24 do_hfs_truncate(struct vnode *vp, off_t length, int flags, int truncateflags)
  25 {
  26     register struct cnode *cp = VTOC(vp);
  27     struct filefork *fp = VTOF(vp);
  28     int retval;
  29     off_t bytesToAdd;
  30     off_t actualBytesAdded;
  31     off_t filebytes;
  32     u_int32_t fileblocks;
  33     int blksize;
  34     struct hfsmount *hfsmp;
  35     int lockflags;
  36     int suppress_times = (truncateflags & HFS_TRUNCATE_SKIPTIMES);
  37
  38     blksize = VTOVCB(vp)->blockSize;
  39     fileblocks = fp->ff_blocks;
  40     filebytes = (off_t)fileblocks * (off_t)blksize;
  41
  42     if (length < 0)
  43         return (EINVAL);
  44
  45     /* This should only happen with a corrupt filesystem */
  46     if ((off_t)fp->ff_size < 0)
  47         return (EINVAL);
  48
  49     hfsmp = VTOHFS(vp);
  50
  51     retval = E_NONE;
  52     /*
  53      * Lengthen the size of the file. We must ensure that the
  54      * last byte of the file is allocated. Since the smallest
  55      * value of ff_size is 0, length will be at least 1.
  56      */
  57     if (length > (off_t)fp->ff_size) {
  58         /*
  59          * If we don't have enough physical space then
  60          * we need to extend the physical size.
  61          */
  62         if (length > filebytes) {
  63             int eflags = kEFReserveMask;
  64             u_int32_t blockHint = 0;
  65
  66             /* All or nothing and don't round up to clumpsize. */
  67             eflags |= kEFAllMask | kEFNoClumpMask;
  68
  69             if (hfs_start_transaction(hfsmp) != 0) {
  70                 retval = EINVAL;
  71                 goto Err_Exit;
  72             }
  73
  74             /* Protect extents b-tree and allocation bitmap */
  75             lockflags = SFL_BITMAP;
  76             if (overflow_extents(fp))
  77                 lockflags |= SFL_EXTENTS;
  78             lockflags = hfs_systemfile_lock(hfsmp, lockflags, HFS_EXCLUSIVE_LOCK);
  79
  80             /*
  81              * Keep growing the file as long as the current EOF is
  82              * less than the desired value.
  83              */
  84             while ((length > filebytes) && (retval == E_NONE)) {
  85                 bytesToAdd = length - filebytes;
  86                 retval = MacToVFSError(ExtendFileC(VTOVCB(vp),
  87                                                    (FCB*)fp,
  88                                                    bytesToAdd,
  89                                                    blockHint,
  90                                                    eflags,
  91                                                    &actualBytesAdded));
  92
  93                 filebytes = (off_t)fp->ff_blocks * (off_t)blksize;
  94                 if (actualBytesAdded == 0 && retval == E_NONE) {
  95                     if (length > filebytes)
  96                         length = filebytes;
  97                     break;
  98                 }
  99             } /* endwhile */
 100
 101             hfs_systemfile_unlock(hfsmp, lockflags);
 102
 103             if (hfsmp->jnl) {
 104                 hfs_update(vp, 0);
 105                 hfs_volupdate(hfsmp, VOL_UPDATE, 0);
 106             }
 107
 108             hfs_end_transaction(hfsmp);
 109
 110             if (retval)
 111                 goto Err_Exit;
 112         }
 113
 114         if (ISSET(flags, IO_NOZEROFILL))
 115         {
 116
 117         }
 118         else
 119         {
 120             if (!vnode_issystem(vp) && retval == E_NONE) {
 121                 if (length > (off_t)fp->ff_size) {
 122                     struct timeval tv;
 123
 124                     /* Extending the file: time to fill out the current last page w. zeroes? */
 125                     retval = raw_readwrite_zero_fill_last_block_suffix(vp);
 126                     if (retval) goto Err_Exit;
 127
 128                     microuptime(&tv);
 129 //                    Currently disabling the rl_add, sice the
 130 //                    data is being filled with 0's and that a valid content for us
 131 //                    rl_add(fp->ff_size, length - 1, &fp->ff_invalidranges);
 132                     cp->c_zftimeout = (uint32_t)tv.tv_sec + ZFTIMELIMIT;
 133                 }
 134             }else{
 135                 LFHFS_LOG(LEVEL_ERROR, "hfs_truncate: invoked on non-UBC object?!");
 136                 hfs_assert(0);
 137             }
 138         }
 139         if (suppress_times == 0) {
 140             cp->c_touch_modtime = TRUE;
 141         }
 142         fp->ff_size = length;
 143
 144     } else { /* Shorten the size of the file */
 145
 146         if ((off_t)fp->ff_size > length) {
 147             /* Any space previously marked as invalid is now irrelevant: */
 148             rl_remove(length, fp->ff_size - 1, &fp->ff_invalidranges);
 149         }
 150
 151         /*
 152          * Account for any unmapped blocks. Note that the new
 153          * file length can still end up with unmapped blocks.
 154          */
 155         if (fp->ff_unallocblocks > 0) {
 156             u_int32_t finalblks;
 157             u_int32_t loanedBlocks;
 158
 159             hfs_lock_mount(hfsmp);
 160             loanedBlocks = fp->ff_unallocblocks;
 161             cp->c_blocks -= loanedBlocks;
 162             fp->ff_blocks -= loanedBlocks;
 163             fp->ff_unallocblocks = 0;
 164
 165             hfsmp->loanedBlocks -= loanedBlocks;
 166
 167             finalblks = (uint32_t)((length + blksize - 1) / blksize);
 168             if (finalblks > fp->ff_blocks) {
 169                 /* calculate required unmapped blocks */
 170                 loanedBlocks = finalblks - fp->ff_blocks;
 171                 hfsmp->loanedBlocks += loanedBlocks;
 172
 173                 fp->ff_unallocblocks = loanedBlocks;
 174                 cp->c_blocks += loanedBlocks;
 175                 fp->ff_blocks += loanedBlocks;
 176             }
 177             hfs_unlock_mount (hfsmp);
 178         }
 179         if (hfs_start_transaction(hfsmp) != 0) {
 180             retval = EINVAL;
 181             goto Err_Exit;
 182         }
 183
 184         if (fp->ff_unallocblocks == 0) {
 185             /* Protect extents b-tree and allocation bitmap */
 186             lockflags = SFL_BITMAP;
 187             if (overflow_extents(fp))
 188                 lockflags |= SFL_EXTENTS;
 189             lockflags = hfs_systemfile_lock(hfsmp, lockflags, HFS_EXCLUSIVE_LOCK);
 190
 191             retval = MacToVFSError(TruncateFileC(VTOVCB(vp), (FCB*)fp, length, 0,
 192                                                  FORK_IS_RSRC (fp), FTOC(fp)->c_fileid, false));
 193
 194             hfs_systemfile_unlock(hfsmp, lockflags);
 195         }
 196         if (hfsmp->jnl) {
 197             if (retval == 0) {
 198                 fp->ff_size = length;
 199             }
 200             hfs_update(vp, 0);
 201             hfs_volupdate(hfsmp, VOL_UPDATE, 0);
 202         }
 203
 204         hfs_end_transaction(hfsmp);
 205
 206         if (retval) goto Err_Exit;
 207
 208         /*
 209          * Only set update flag if the logical length changes & we aren't
 210          * suppressing modtime updates.
 211          */
 212         if (((off_t)fp->ff_size != length) && (suppress_times == 0)) {
 213             cp->c_touch_modtime = TRUE;
 214         }
 215         fp->ff_size = length;
 216     }
 217
 218     cp->c_flag |= C_MODIFIED;
 219     cp->c_touch_chgtime = TRUE;    /* status changed */
 220     if (suppress_times == 0) {
 221         cp->c_touch_modtime = TRUE;    /* file data was modified */
 222
 223         /*
 224          * If we are not suppressing the modtime update, then
 225          * update the gen count as well.
 226          */
 227         if (S_ISREG(cp->c_attr.ca_mode) || S_ISLNK (cp->c_attr.ca_mode)) {
 228             hfs_incr_gencount(cp);
 229         }
 230     }
 231
 232     retval = hfs_update(vp, 0);
 233
 234 Err_Exit:
 235
 236     return (retval);
 237 }
 238
 239 int
 240 hfs_vnop_blockmap(struct vnop_blockmap_args *ap)
 241 {
 242     struct vnode *vp = ap->a_vp;
 243     struct cnode *cp;
 244     struct filefork *fp;
 245     struct hfsmount *hfsmp;
 246     size_t bytesContAvail = ap->a_size;
 247     int retval = E_NONE;
 248     int syslocks = 0;
 249     int lockflags = 0;
 250     struct rl_entry *invalid_range;
 251     enum rl_overlaptype overlaptype;
 252     int started_tr = 0;
 253     int tooklock = 0;
 254
 255     /* Do not allow blockmap operation on a directory */
 256     if (vnode_isdir(vp)) {
 257         return (ENOTSUP);
 258     }
 259
 260     /*
 261      * Check for underlying vnode requests and ensure that logical
 262      * to physical mapping is requested.
 263      */
 264     if (ap->a_bpn == NULL)
 265         return (0);
 266
 267     hfsmp = VTOHFS(vp);
 268     cp = VTOC(vp);
 269     fp = VTOF(vp);
 270
 271     if ( !vnode_issystem(vp) && !vnode_islnk(vp) ) {
 272         if (cp->c_lockowner != pthread_self()) {
 273             hfs_lock(VTOC(vp), HFS_EXCLUSIVE_LOCK, HFS_LOCK_ALLOW_NOEXISTS);
 274             tooklock = 1;
 275         }
 276
 277         // For reads, check the invalid ranges
 278         if (ISSET(ap->a_flags, VNODE_READ)) {
 279             if (ap->a_foffset >= fp->ff_size) {
 280                 retval = ERANGE;
 281                 goto exit;
 282             }
 283
 284             overlaptype = rl_scan(&fp->ff_invalidranges, ap->a_foffset,
 285                                   ap->a_foffset + (off_t)bytesContAvail - 1,
 286                                   &invalid_range);
 287             switch(overlaptype) {
 288                 case RL_MATCHINGOVERLAP:
 289                 case RL_OVERLAPCONTAINSRANGE:
 290                 case RL_OVERLAPSTARTSBEFORE:
 291                     /* There's no valid block for this byte offset */
 292                     *ap->a_bpn = (daddr64_t)-1;
 293                     /* There's no point limiting the amount to be returned
 294                      * if the invalid range that was hit extends all the way
 295                      * to the EOF (i.e. there's no valid bytes between the
 296                      * end of this range and the file's EOF):
 297                      */
 298                     if (((off_t)fp->ff_size > (invalid_range->rl_end + 1)) &&
 299                         ((size_t)(invalid_range->rl_end + 1 - ap->a_foffset) < bytesContAvail)) {
 300                         bytesContAvail = invalid_range->rl_end + 1 - ap->a_foffset;
 301                     }
 302
 303                     retval = 0;
 304                     goto exit;
 305
 306                 case RL_OVERLAPISCONTAINED:
 307                 case RL_OVERLAPENDSAFTER:
 308                     /* The range of interest hits an invalid block before the end: */
 309                     if (invalid_range->rl_start == ap->a_foffset) {
 310                         /* There's actually no valid information to be had starting here: */
 311                         *ap->a_bpn = (daddr64_t)-1;
 312                         if (((off_t)fp->ff_size > (invalid_range->rl_end + 1)) &&
 313                             ((size_t)(invalid_range->rl_end + 1 - ap->a_foffset) < bytesContAvail)) {
 314                             bytesContAvail = invalid_range->rl_end + 1 - ap->a_foffset;
 315                         }
 316
 317                         retval = 0;
 318                         goto exit;
 319                     } else {
 320                         /*
 321                          * Sadly, the lower layers don't like us to
 322                          * return unaligned ranges, so we skip over
 323                          * any invalid ranges here that are less than
 324                          * a page: zeroing of those bits is not our
 325                          * responsibility (it's dealt with elsewhere).
 326                          */
 327                         do {
 328                             off_t rounded_start = (((uint64_t)(invalid_range->rl_start) + (off_t)PAGE_MASK) & ~((off_t)PAGE_MASK));
 329                             if ((off_t)bytesContAvail < rounded_start - ap->a_foffset)
 330                                 break;
 331                             if (rounded_start < invalid_range->rl_end + 1) {
 332                                 bytesContAvail = rounded_start - ap->a_foffset;
 333                                 break;
 334                             }
 335                         } while ((invalid_range = TAILQ_NEXT(invalid_range,
 336                                                              rl_link)));
 337                     }
 338                     break;
 339
 340                 case RL_NOOVERLAP:
 341                     break;
 342             } // switch
 343         }
 344     }
 345
 346 retry:
 347
 348     /* Check virtual blocks only when performing write operation */
 349     if ((ap->a_flags & VNODE_WRITE) && (fp->ff_unallocblocks != 0)) {
 350         if (hfs_start_transaction(hfsmp) != 0) {
 351             retval = EINVAL;
 352             goto exit;
 353         } else {
 354             started_tr = 1;
 355         }
 356         syslocks = SFL_EXTENTS | SFL_BITMAP;
 357
 358     } else if (overflow_extents(fp)) {
 359         syslocks = SFL_EXTENTS;
 360     }
 361
 362     if (syslocks)
 363         lockflags = hfs_systemfile_lock(hfsmp, syslocks, HFS_EXCLUSIVE_LOCK);
 364
 365     /*
 366      * Check for any delayed allocations.
 367      */
 368     if ((ap->a_flags & VNODE_WRITE) && (fp->ff_unallocblocks != 0)) {
 369         int64_t actbytes;
 370         u_int32_t loanedBlocks;
 371
 372         //
 373         // Make sure we have a transaction.  It's possible
 374         // that we came in and fp->ff_unallocblocks was zero
 375         // but during the time we blocked acquiring the extents
 376         // btree, ff_unallocblocks became non-zero and so we
 377         // will need to start a transaction.
 378         //
 379         if (started_tr == 0) {
 380             if (syslocks) {
 381                 hfs_systemfile_unlock(hfsmp, lockflags);
 382                 syslocks = 0;
 383             }
 384             goto retry;
 385         }
 386
 387         /*
 388          * Note: ExtendFileC will Release any blocks on loan and
 389          * aquire real blocks.  So we ask to extend by zero bytes
 390          * since ExtendFileC will account for the virtual blocks.
 391          */
 392
 393         loanedBlocks = fp->ff_unallocblocks;
 394         retval = ExtendFileC(hfsmp, (FCB*)fp, 0, 0,
 395                              kEFAllMask | kEFNoClumpMask, &actbytes);
 396
 397         if (retval) {
 398             fp->ff_unallocblocks = loanedBlocks;
 399             cp->c_blocks += loanedBlocks;
 400             fp->ff_blocks += loanedBlocks;
 401
 402             hfs_lock_mount (hfsmp);
 403             hfsmp->loanedBlocks += loanedBlocks;
 404             hfs_unlock_mount (hfsmp);
 405
 406             hfs_systemfile_unlock(hfsmp, lockflags);
 407             cp->c_flag |= C_MODIFIED;
 408             if (started_tr) {
 409                 (void) hfs_update(vp, 0);
 410                 (void) hfs_volupdate(hfsmp, VOL_UPDATE, 0);
 411
 412                 hfs_end_transaction(hfsmp);
 413                 started_tr = 0;
 414             }
 415             goto exit;
 416         }
 417     }
 418
 419     retval = MapFileBlockC(hfsmp, (FCB *)fp, bytesContAvail, ap->a_foffset,
 420                            ap->a_bpn, &bytesContAvail);
 421     if (syslocks) {
 422         hfs_systemfile_unlock(hfsmp, lockflags);
 423     }
 424
 425     if (retval) {
 426         /* On write, always return error because virtual blocks, if any,
 427          * should have been allocated in ExtendFileC().  We do not
 428          * allocate virtual blocks on read, therefore return error
 429          * only if no virtual blocks are allocated.  Otherwise we search
 430          * rangelist for zero-fills
 431          */
 432         if ((MacToVFSError(retval) != ERANGE) ||
 433             (ap->a_flags & VNODE_WRITE) ||
 434             ((ap->a_flags & VNODE_READ) && (fp->ff_unallocblocks == 0))) {
 435             goto exit;
 436         }
 437
 438         /* Validate if the start offset is within logical file size */
 439         if (ap->a_foffset >= fp->ff_size) {
 440             goto exit;
 441         }
 442
 443         /*
 444          * At this point, we have encountered a failure during
 445          * MapFileBlockC that resulted in ERANGE, and we are not
 446          * servicing a write, and there are borrowed blocks.
 447          *
 448          * However, the cluster layer will not call blockmap for
 449          * blocks that are borrowed and in-cache.  We have to assume
 450          * that because we observed ERANGE being emitted from
 451          * MapFileBlockC, this extent range is not valid on-disk.  So
 452          * we treat this as a mapping that needs to be zero-filled
 453          * prior to reading.
 454          */
 455
 456         if (fp->ff_size - ap->a_foffset < (off_t)bytesContAvail)
 457             bytesContAvail = fp->ff_size - ap->a_foffset;
 458
 459         *ap->a_bpn = (daddr64_t) -1;
 460         retval = 0;
 461
 462         goto exit;
 463     }
 464
 465 exit:
 466     if (retval == 0) {
 467         if (ISSET(ap->a_flags, VNODE_WRITE)) {
 468             struct rl_entry *r = TAILQ_FIRST(&fp->ff_invalidranges);
 469
 470             // See if we might be overlapping invalid ranges...
 471             if (r && (ap->a_foffset + (off_t)bytesContAvail) > r->rl_start) {
 472                 /*
 473                  * Mark the file as needing an update if we think the
 474                  * on-disk EOF has changed.
 475                  */
 476                 if (ap->a_foffset <= r->rl_start)
 477                     SET(cp->c_flag, C_MODIFIED);
 478
 479                 /*
 480                  * This isn't the ideal place to put this.  Ideally, we
 481                  * should do something *after* we have successfully
 482                  * written to the range, but that's difficult to do
 483                  * because we cannot take locks in the callback.  At
 484                  * present, the cluster code will call us with VNODE_WRITE
 485                  * set just before it's about to write the data so we know
 486                  * that data is about to be written.  If we get an I/O
 487                  * error at this point then chances are the metadata
 488                  * update to follow will also have an I/O error so the
 489                  * risk here is small.
 490                  */
 491                 rl_remove(ap->a_foffset, ap->a_foffset + bytesContAvail - 1,
 492                           &fp->ff_invalidranges);
 493
 494                 if (!TAILQ_FIRST(&fp->ff_invalidranges)) {
 495                     cp->c_flag &= ~C_ZFWANTSYNC;
 496                     cp->c_zftimeout = 0;
 497                 }
 498             }
 499         }
 500
 501         if (ap->a_run)
 502             *ap->a_run = bytesContAvail;
 503
 504         if (ap->a_poff)
 505             *(int *)ap->a_poff = 0;
 506     }
 507
 508     if (started_tr) {
 509         hfs_update(vp, TRUE);
 510         hfs_volupdate(hfsmp, VOL_UPDATE, 0);
 511         hfs_end_transaction(hfsmp);
 512     }
 513
 514     if (tooklock)
 515         hfs_unlock(cp);
 516
 517     return (MacToVFSError(retval));
 518 }
 519
 520 int
 521 hfs_prepare_release_storage (struct hfsmount *hfsmp, struct vnode *vp) {
 522
 523     struct filefork *fp = VTOF(vp);
 524     struct cnode *cp = VTOC(vp);
 525
 526     /* Cannot truncate an HFS directory! */
 527     if (IS_DIR(vp))
 528     {
 529         return (EISDIR);
 530     }
 531
 532     /* This should only happen with a corrupt filesystem */
 533     if ((off_t)fp->ff_size < 0)
 534         return (EINVAL);
 535
 536     /*
 537      * We cannot just check if fp->ff_size == length (as an optimization)
 538      * since there may be extra physical blocks that also need truncation.
 539      */
 540
 541     /* Wipe out any invalid ranges which have yet to be backed by disk */
 542     rl_remove(0, fp->ff_size - 1, &fp->ff_invalidranges);
 543
 544     /*
 545      * Account for any unmapped blocks. Since we're deleting the
 546      * entire file, we don't have to worry about just shrinking
 547      * to a smaller number of borrowed blocks.
 548      */
 549     if (fp->ff_unallocblocks > 0)
 550     {
 551         u_int32_t loanedBlocks;
 552
 553         hfs_lock_mount (hfsmp);
 554         loanedBlocks = fp->ff_unallocblocks;
 555         cp->c_blocks -= loanedBlocks;
 556         fp->ff_blocks -= loanedBlocks;
 557         fp->ff_unallocblocks = 0;
 558
 559         hfsmp->loanedBlocks -= loanedBlocks;
 560
 561         hfs_unlock_mount (hfsmp);
 562     }
 563
 564     return 0;
 565 }
 566
 567 int
 568 hfs_release_storage (struct hfsmount *hfsmp, struct filefork *datafork, struct filefork *rsrcfork, u_int32_t fileid)
 569 {
 570     int error = 0;
 571     int blksize = hfsmp->blockSize;
 572
 573     /* Data Fork */
 574     if (datafork)
 575     {
 576         datafork->ff_size = 0;
 577
 578         u_int32_t fileblocks = datafork->ff_blocks;
 579         off_t filebytes = (off_t)fileblocks * (off_t)blksize;
 580
 581         /* We killed invalid ranges and loaned blocks before we removed the catalog entry */
 582
 583         while (filebytes > 0) {
 584             if (filebytes > HFS_BIGFILE_SIZE) {
 585                 filebytes -= HFS_BIGFILE_SIZE;
 586             } else {
 587                 filebytes = 0;
 588             }
 589
 590             /* Start a transaction, and wipe out as many blocks as we can in this iteration */
 591             if (hfs_start_transaction(hfsmp) != 0) {
 592                 error = EINVAL;
 593                 break;
 594             }
 595
 596             if (datafork->ff_unallocblocks == 0)
 597             {
 598                 /* Protect extents b-tree and allocation bitmap */
 599                 int lockflags = SFL_BITMAP;
 600                 if (overflow_extents(datafork))
 601                     lockflags |= SFL_EXTENTS;
 602                 lockflags = hfs_systemfile_lock(hfsmp, lockflags, HFS_EXCLUSIVE_LOCK);
 603
 604                 error = MacToVFSError(TruncateFileC(HFSTOVCB(hfsmp), datafork, filebytes, 1, 0, fileid, false));
 605
 606                 hfs_systemfile_unlock(hfsmp, lockflags);
 607             }
 608             (void) hfs_volupdate(hfsmp, VOL_UPDATE, 0);
 609
 610             /* Finish the transaction and start over if necessary */
 611             hfs_end_transaction(hfsmp);
 612
 613             if (error) {
 614                 break;
 615             }
 616         }
 617     }
 618
 619     /* Resource fork */
 620     if (error == 0 && rsrcfork)
 621     {
 622         rsrcfork->ff_size = 0;
 623
 624         u_int32_t fileblocks = rsrcfork->ff_blocks;
 625         off_t filebytes = (off_t)fileblocks * (off_t)blksize;
 626
 627         /* We killed invalid ranges and loaned blocks before we removed the catalog entry */
 628
 629         while (filebytes > 0)
 630         {
 631             if (filebytes > HFS_BIGFILE_SIZE)
 632             {
 633                 filebytes -= HFS_BIGFILE_SIZE;
 634             }
 635             else
 636             {
 637                 filebytes = 0;
 638             }
 639
 640             /* Start a transaction, and wipe out as many blocks as we can in this iteration */
 641             if (hfs_start_transaction(hfsmp) != 0)
 642             {
 643                 error = EINVAL;
 644                 break;
 645             }
 646
 647             if (rsrcfork->ff_unallocblocks == 0)
 648             {
 649                 /* Protect extents b-tree and allocation bitmap */
 650                 int lockflags = SFL_BITMAP;
 651                 if (overflow_extents(rsrcfork))
 652                     lockflags |= SFL_EXTENTS;
 653                 lockflags = hfs_systemfile_lock(hfsmp, lockflags, HFS_EXCLUSIVE_LOCK);
 654
 655                 error = MacToVFSError(TruncateFileC(HFSTOVCB(hfsmp), rsrcfork, filebytes, 1, 1, fileid, false));
 656
 657                 hfs_systemfile_unlock(hfsmp, lockflags);
 658             }
 659             (void) hfs_volupdate(hfsmp, VOL_UPDATE, 0);
 660
 661             /* Finish the transaction and start over if necessary */
 662             hfs_end_transaction(hfsmp);
 663
 664             if (error)
 665             {
 666                 break;
 667             }
 668         }
 669     }
 670
 671     return error;
 672 }
 673
 674 /*
 675  * Truncate a cnode to at most length size, freeing (or adding) the
 676  * disk blocks.
 677  */
 678 int
 679 hfs_truncate(struct vnode *vp, off_t length, int flags, int truncateflags)
 680 {
 681     struct filefork *fp = VTOF(vp);
 682     off_t filebytes;
 683     u_int32_t fileblocks;
 684     int blksize;
 685     errno_t error = 0;
 686     struct cnode *cp = VTOC(vp);
 687     hfsmount_t *hfsmp = VTOHFS(vp);
 688
 689     /* Cannot truncate an HFS directory! */
 690     if (vnode_isdir(vp)) {
 691         return (EISDIR);
 692     }
 693
 694     blksize = hfsmp->blockSize;
 695     fileblocks = fp->ff_blocks;
 696     filebytes = (off_t)fileblocks * (off_t)blksize;
 697
 698     bool caller_has_cnode_lock = (cp->c_lockowner == pthread_self());
 699
 700     if (!caller_has_cnode_lock) {
 701         error = hfs_lock(cp, HFS_EXCLUSIVE_LOCK, HFS_LOCK_DEFAULT);
 702         if (error)
 703             return error;
 704     }
 705
 706     if (vnode_islnk(vp) && cp->c_datafork->ff_symlinkptr) {
 707         hfs_free(cp->c_datafork->ff_symlinkptr);
 708         cp->c_datafork->ff_symlinkptr = NULL;
 709     }
 710
 711     // have to loop truncating or growing files that are
 712     // really big because otherwise transactions can get
 713     // enormous and consume too many kernel resources.
 714
 715     if (length < filebytes) {
 716         while (filebytes > length) {
 717             if ((filebytes - length) > HFS_BIGFILE_SIZE) {
 718                 filebytes -= HFS_BIGFILE_SIZE;
 719             } else {
 720                 filebytes = length;
 721             }
 722             error = do_hfs_truncate(vp, filebytes, flags, truncateflags);
 723             if (error)
 724                 break;
 725         }
 726     } else if (length > filebytes) {
 727         const bool keep_reserve = false; //cred && suser(cred, NULL) != 0;
 728
 729         if (hfs_freeblks(hfsmp, keep_reserve) < howmany(length - filebytes, blksize))
 730         {
 731             error = ENOSPC;
 732         }
 733         else
 734         {
 735             while (filebytes < length) {
 736                 if ((length - filebytes) > HFS_BIGFILE_SIZE) {
 737                     filebytes += HFS_BIGFILE_SIZE;
 738                 } else {
 739                     filebytes = length;
 740                 }
 741                 error = do_hfs_truncate(vp, filebytes, flags, truncateflags);
 742                 if (error)
 743                     break;
 744             }
 745         }
 746     } else /* Same logical size */ {
 747
 748         error = do_hfs_truncate(vp, length, flags, truncateflags);
 749     }
 750
 751     if (!caller_has_cnode_lock)
 752         hfs_unlock(cp);
 753
 754     return error;
 755 }