source3/locking/posix.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Locking functions
   4    Copyright (C) Jeremy Allison 1992-2000
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19
  20    Revision History:
  21
  22    POSIX locking support. Jeremy Allison (jeremy@valinux.com), Apr. 2000.
  23 */
  24
  25 #include "includes.h"
  26
  27 /*
  28  * The POSIX locking database handle.
  29  */
  30
  31 static TDB_CONTEXT *posix_lock_tdb;
  32
  33 /*
  34  * The pending close database handle.
  35  */
  36
  37 static TDB_CONTEXT *posix_pending_close_tdb;
  38
  39 /*
  40  * The data in POSIX lock records is an unsorted linear array of these
  41  * records.  It is unnecessary to store the count as tdb provides the
  42  * size of the record.
  43  */
  44
  45 struct posix_lock {
  46         int fd;
  47         SMB_OFF_T start;
  48         SMB_OFF_T size;
  49         int lock_type;
  50 };
  51
  52 /*
  53  * The data in POSIX pending close records is an unsorted linear array of int
  54  * records.  It is unnecessary to store the count as tdb provides the
  55  * size of the record.
  56  */
  57
  58 /* The key used in both the POSIX databases. */
  59
  60 struct posix_lock_key {
  61         SMB_DEV_T device;
  62         SMB_INO_T inode;
  63 };
  64
  65 /*******************************************************************
  66  Form a static locking key for a dev/inode pair.
  67 ******************************************************************/
  68
  69 static TDB_DATA locking_key(SMB_DEV_T dev, SMB_INO_T inode)
  70 {
  71         static struct posix_lock_key key;
  72         TDB_DATA kbuf;
  73
  74         memset(&key, '\0', sizeof(key));
  75         key.device = dev;
  76         key.inode = inode;
  77         kbuf.dptr = (char *)&key;
  78         kbuf.dsize = sizeof(key);
  79         return kbuf;
  80 }
  81
  82 /*******************************************************************
  83  Convenience function to get a key from an fsp.
  84 ******************************************************************/
  85
  86 static TDB_DATA locking_key_fsp(files_struct *fsp)
  87 {
  88         return locking_key(fsp->dev, fsp->inode);
  89 }
  90
  91 /****************************************************************************
  92  Add an fd to the pending close tdb.
  93 ****************************************************************************/
  94
  95 static BOOL add_fd_to_close_entry(files_struct *fsp)
  96 {
  97         TDB_DATA kbuf = locking_key_fsp(fsp);
  98         TDB_DATA dbuf;
  99         char *tp;
 100
 101         dbuf.dptr = NULL;
 102
 103         dbuf = tdb_fetch(posix_pending_close_tdb, kbuf);
 104
 105         tp = SMB_REALLOC(dbuf.dptr, dbuf.dsize + sizeof(int));
 106         if (!tp) {
 107                 DEBUG(0,("add_fd_to_close_entry: Realloc fail !\n"));
 108                 SAFE_FREE(dbuf.dptr);
 109                 return False;
 110         } else
 111                 dbuf.dptr = tp;
 112
 113         memcpy(dbuf.dptr + dbuf.dsize, &fsp->fd, sizeof(int));
 114         dbuf.dsize += sizeof(int);
 115
 116         if (tdb_store(posix_pending_close_tdb, kbuf, dbuf, TDB_REPLACE) == -1) {
 117                 DEBUG(0,("add_fd_to_close_entry: tdb_store fail !\n"));
 118         }
 119
 120         SAFE_FREE(dbuf.dptr);
 121         return True;
 122 }
 123
 124 /****************************************************************************
 125  Remove all fd entries for a specific dev/inode pair from the tdb.
 126 ****************************************************************************/
 127
 128 static void delete_close_entries(files_struct *fsp)
 129 {
 130         TDB_DATA kbuf = locking_key_fsp(fsp);
 131
 132         if (tdb_delete(posix_pending_close_tdb, kbuf) == -1)
 133                 DEBUG(0,("delete_close_entries: tdb_delete fail !\n"));
 134 }
 135
 136 /****************************************************************************
 137  Get the array of POSIX pending close records for an open fsp. Caller must
 138  free. Returns number of entries.
 139 ****************************************************************************/
 140
 141 static size_t get_posix_pending_close_entries(files_struct *fsp, int **entries)
 142 {
 143         TDB_DATA kbuf = locking_key_fsp(fsp);
 144         TDB_DATA dbuf;
 145         size_t count = 0;
 146
 147         *entries = NULL;
 148         dbuf.dptr = NULL;
 149
 150         dbuf = tdb_fetch(posix_pending_close_tdb, kbuf);
 151
 152         if (!dbuf.dptr) {
 153                 return 0;
 154         }
 155
 156         *entries = (int *)dbuf.dptr;
 157         count = (size_t)(dbuf.dsize / sizeof(int));
 158
 159         return count;
 160 }
 161
 162 /****************************************************************************
 163  Get the array of POSIX locks for an fsp. Caller must free. Returns
 164  number of entries.
 165 ****************************************************************************/
 166
 167 static size_t get_posix_lock_entries(files_struct *fsp, struct posix_lock **entries)
 168 {
 169         TDB_DATA kbuf = locking_key_fsp(fsp);
 170         TDB_DATA dbuf;
 171         size_t count = 0;
 172
 173         *entries = NULL;
 174
 175         dbuf.dptr = NULL;
 176
 177         dbuf = tdb_fetch(posix_lock_tdb, kbuf);
 178
 179         if (!dbuf.dptr) {
 180                 return 0;
 181         }
 182
 183         *entries = (struct posix_lock *)dbuf.dptr;
 184         count = (size_t)(dbuf.dsize / sizeof(struct posix_lock));
 185
 186         return count;
 187 }
 188
 189 /****************************************************************************
 190  Deal with pending closes needed by POSIX locking support.
 191  Note that posix_locking_close_file() is expected to have been called
 192  to delete all locks on this fsp before this function is called.
 193 ****************************************************************************/
 194
 195 int fd_close_posix(struct connection_struct *conn, files_struct *fsp)
 196 {
 197         int saved_errno = 0;
 198         int ret;
 199         size_t count, i;
 200         struct posix_lock *entries = NULL;
 201         int *fd_array = NULL;
 202         BOOL locks_on_other_fds = False;
 203
 204         if (!lp_posix_locking(SNUM(conn))) {
 205                 /*
 206                  * No POSIX to worry about, just close.
 207                  */
 208                 ret = SMB_VFS_CLOSE(fsp,fsp->fd);
 209                 fsp->fd = -1;
 210                 return ret;
 211         }
 212
 213         /*
 214          * Get the number of outstanding POSIX locks on this dev/inode pair.
 215          */
 216
 217         count = get_posix_lock_entries(fsp, &entries);
 218
 219         /*
 220          * Check if there are any outstanding locks belonging to
 221          * other fd's. This should never be the case if posix_locking_close_file()
 222          * has been called first, but it never hurts to be *sure*.
 223          */
 224
 225         for (i = 0; i < count; i++) {
 226                 if (entries[i].fd != fsp->fd) {
 227                         locks_on_other_fds = True;
 228                         break;
 229                 }
 230         }
 231
 232         if (locks_on_other_fds) {
 233
 234                 /*
 235                  * There are outstanding locks on this dev/inode pair on other fds.
 236                  * Add our fd to the pending close tdb and set fsp->fd to -1.
 237                  */
 238
 239                 if (!add_fd_to_close_entry(fsp)) {
 240                         SAFE_FREE(entries);
 241                         return -1;
 242                 }
 243
 244                 SAFE_FREE(entries);
 245                 fsp->fd = -1;
 246                 return 0;
 247         }
 248
 249         SAFE_FREE(entries);
 250
 251         /*
 252          * No outstanding POSIX locks. Get the pending close fd's
 253          * from the tdb and close them all.
 254          */
 255
 256         count = get_posix_pending_close_entries(fsp, &fd_array);
 257
 258         if (count) {
 259                 DEBUG(10,("fd_close_posix: doing close on %u fd's.\n", (unsigned int)count ));
 260
 261                 for(i = 0; i < count; i++) {
 262                         if (SMB_VFS_CLOSE(fsp,fd_array[i]) == -1) {
 263                                 saved_errno = errno;
 264                         }
 265                 }
 266
 267                 /*
 268                  * Delete all fd's stored in the tdb
 269                  * for this dev/inode pair.
 270                  */
 271
 272                 delete_close_entries(fsp);
 273         }
 274
 275         SAFE_FREE(fd_array);
 276
 277         /*
 278          * Finally close the fd associated with this fsp.
 279          */
 280
 281         ret = SMB_VFS_CLOSE(fsp,fsp->fd);
 282
 283         if (saved_errno != 0) {
 284                 errno = saved_errno;
 285                 ret = -1;
 286         }
 287
 288         fsp->fd = -1;
 289
 290         return ret;
 291 }
 292
 293 /****************************************************************************
 294  Debugging aid :-).
 295 ****************************************************************************/
 296
 297 static const char *posix_lock_type_name(int lock_type)
 298 {
 299         return (lock_type == F_RDLCK) ? "READ" : "WRITE";
 300 }
 301
 302 /****************************************************************************
 303  Delete a POSIX lock entry by index number. Used if the tdb add succeeds, but
 304  then the POSIX fcntl lock fails.
 305 ****************************************************************************/
 306
 307 static BOOL delete_posix_lock_entry_by_index(files_struct *fsp, size_t entry)
 308 {
 309         TDB_DATA kbuf = locking_key_fsp(fsp);
 310         TDB_DATA dbuf;
 311         struct posix_lock *locks;
 312         size_t count;
 313
 314         dbuf.dptr = NULL;
 315
 316         dbuf = tdb_fetch(posix_lock_tdb, kbuf);
 317
 318         if (!dbuf.dptr) {
 319                 DEBUG(10,("delete_posix_lock_entry_by_index: tdb_fetch failed !\n"));
 320                 goto fail;
 321         }
 322
 323         count = (size_t)(dbuf.dsize / sizeof(struct posix_lock));
 324         locks = (struct posix_lock *)dbuf.dptr;
 325
 326         if (count == 1) {
 327                 tdb_delete(posix_lock_tdb, kbuf);
 328         } else {
 329                 if (entry < count-1) {
 330                         memmove(&locks[entry], &locks[entry+1], sizeof(*locks)*((count-1) - entry));
 331                 }
 332                 dbuf.dsize -= sizeof(*locks);
 333                 tdb_store(posix_lock_tdb, kbuf, dbuf, TDB_REPLACE);
 334         }
 335
 336         SAFE_FREE(dbuf.dptr);
 337
 338         return True;
 339
 340  fail:
 341
 342         SAFE_FREE(dbuf.dptr);
 343         return False;
 344 }
 345
 346 /****************************************************************************
 347  Add an entry into the POSIX locking tdb. We return the index number of the
 348  added lock (used in case we need to delete *exactly* this entry). Returns
 349  False on fail, True on success.
 350 ****************************************************************************/
 351
 352 static BOOL add_posix_lock_entry(files_struct *fsp, SMB_OFF_T start, SMB_OFF_T size, int lock_type, size_t *pentry_num)
 353 {
 354         TDB_DATA kbuf = locking_key_fsp(fsp);
 355         TDB_DATA dbuf;
 356         struct posix_lock pl;
 357         char *tp;
 358
 359         dbuf.dptr = NULL;
 360
 361         dbuf = tdb_fetch(posix_lock_tdb, kbuf);
 362
 363         *pentry_num = (size_t)(dbuf.dsize / sizeof(pl));
 364
 365         /*
 366          * Add new record.
 367          */
 368
 369         pl.fd = fsp->fd;
 370         pl.start = start;
 371         pl.size = size;
 372         pl.lock_type = lock_type;
 373
 374         tp = SMB_REALLOC(dbuf.dptr, dbuf.dsize + sizeof(pl));
 375         if (!tp) {
 376                 DEBUG(0,("add_posix_lock_entry: Realloc fail !\n"));
 377                 goto fail;
 378         } else
 379                 dbuf.dptr = tp;
 380
 381         memcpy(dbuf.dptr + dbuf.dsize, &pl, sizeof(pl));
 382         dbuf.dsize += sizeof(pl);
 383
 384         if (tdb_store(posix_lock_tdb, kbuf, dbuf, TDB_REPLACE) == -1) {
 385                 DEBUG(0,("add_posix_lock: Failed to add lock entry on file %s\n", fsp->fsp_name));
 386                 goto fail;
 387         }
 388
 389         SAFE_FREE(dbuf.dptr);
 390
 391         DEBUG(10,("add_posix_lock: File %s: type = %s: start=%.0f size=%.0f: dev=%.0f inode=%.0f\n",
 392                         fsp->fsp_name, posix_lock_type_name(lock_type), (double)start, (double)size,
 393                         (double)fsp->dev, (double)fsp->inode ));
 394
 395         return True;
 396
 397  fail:
 398
 399         SAFE_FREE(dbuf.dptr);
 400         return False;
 401 }
 402
 403 /****************************************************************************
 404  Calculate if locks have any overlap at all.
 405 ****************************************************************************/
 406
 407 static BOOL does_lock_overlap(SMB_OFF_T start1, SMB_OFF_T size1, SMB_OFF_T start2, SMB_OFF_T size2)
 408 {
 409         if (start1 >= start2 && start1 <= start2 + size2)
 410                 return True;
 411
 412         if (start1 < start2 && start1 + size1 > start2)
 413                 return True;
 414
 415         return False;
 416 }
 417
 418 /****************************************************************************
 419  Delete an entry from the POSIX locking tdb. Returns a copy of the entry being
 420  deleted and the number of records that are overlapped by this one, or -1 on error.
 421 ****************************************************************************/
 422
 423 static int delete_posix_lock_entry(files_struct *fsp, SMB_OFF_T start, SMB_OFF_T size, struct posix_lock *pl)
 424 {
 425         TDB_DATA kbuf = locking_key_fsp(fsp);
 426         TDB_DATA dbuf;
 427         struct posix_lock *locks;
 428         size_t i, count;
 429         BOOL found = False;
 430         int num_overlapping_records = 0;
 431
 432         dbuf.dptr = NULL;
 433
 434         dbuf = tdb_fetch(posix_lock_tdb, kbuf);
 435
 436         if (!dbuf.dptr) {
 437                 DEBUG(10,("delete_posix_lock_entry: tdb_fetch failed !\n"));
 438                 goto fail;
 439         }
 440
 441         /* There are existing locks - find a match. */
 442         locks = (struct posix_lock *)dbuf.dptr;
 443         count = (size_t)(dbuf.dsize / sizeof(*locks));
 444
 445         /*
 446          * Search for and delete the first record that matches the
 447          * unlock criteria.
 448          */
 449
 450         for (i=0; i<count; i++) {
 451                 struct posix_lock *entry = &locks[i];
 452
 453                 if (entry->fd == fsp->fd &&
 454                         entry->start == start &&
 455                         entry->size == size) {
 456
 457                         /* Make a copy if requested. */
 458                         if (pl)
 459                                 *pl = *entry;
 460
 461                         /* Found it - delete it. */
 462                         if (count == 1) {
 463                                 tdb_delete(posix_lock_tdb, kbuf);
 464                         } else {
 465                                 if (i < count-1) {
 466                                         memmove(&locks[i], &locks[i+1], sizeof(*locks)*((count-1) - i));
 467                                 }
 468                                 dbuf.dsize -= sizeof(*locks);
 469                                 tdb_store(posix_lock_tdb, kbuf, dbuf, TDB_REPLACE);
 470                         }
 471                         count--;
 472                         found = True;
 473                         break;
 474                 }
 475         }
 476
 477         if (!found)
 478                 goto fail;
 479
 480         /*
 481          * Count the number of entries that are
 482          * overlapped by this unlock request.
 483          */
 484
 485         for (i = 0; i < count; i++) {
 486                 struct posix_lock *entry = &locks[i];
 487
 488                 if (fsp->fd == entry->fd &&
 489                         does_lock_overlap( start, size, entry->start, entry->size))
 490                                 num_overlapping_records++;
 491         }
 492
 493         DEBUG(10,("delete_posix_lock_entry: type = %s: start=%.0f size=%.0f, num_records = %d\n",
 494                         posix_lock_type_name(pl->lock_type), (double)pl->start, (double)pl->size,
 495                                 (unsigned int)num_overlapping_records ));
 496
 497         SAFE_FREE(dbuf.dptr);
 498
 499         return num_overlapping_records;
 500
 501  fail:
 502
 503         SAFE_FREE(dbuf.dptr);
 504         return -1;
 505 }
 506
 507 /****************************************************************************
 508  Utility function to map a lock type correctly depending on the open
 509  mode of a file.
 510 ****************************************************************************/
 511
 512 static int map_posix_lock_type( files_struct *fsp, enum brl_type lock_type)
 513 {
 514         if((lock_type == WRITE_LOCK) && !fsp->can_write) {
 515                 /*
 516                  * Many UNIX's cannot get a write lock on a file opened read-only.
 517                  * Win32 locking semantics allow this.
 518                  * Do the best we can and attempt a read-only lock.
 519                  */
 520                 DEBUG(10,("map_posix_lock_type: Downgrading write lock to read due to read-only file.\n"));
 521                 return F_RDLCK;
 522         } else if((lock_type == READ_LOCK) && !fsp->can_read) {
 523                 /*
 524                  * Ditto for read locks on write only files.
 525                  */
 526                 DEBUG(10,("map_posix_lock_type: Changing read lock to write due to write-only file.\n"));
 527                 return F_WRLCK;
 528         }
 529
 530   /*
 531    * This return should be the most normal, as we attempt
 532    * to always open files read/write.
 533    */
 534
 535   return (lock_type == READ_LOCK) ? F_RDLCK : F_WRLCK;
 536 }
 537
 538 /****************************************************************************
 539  Check to see if the given unsigned lock range is within the possible POSIX
 540  range. Modifies the given args to be in range if possible, just returns
 541  False if not.
 542 ****************************************************************************/
 543
 544 static BOOL posix_lock_in_range(SMB_OFF_T *offset_out, SMB_OFF_T *count_out,
 545                                                                 SMB_BIG_UINT u_offset, SMB_BIG_UINT u_count)
 546 {
 547         SMB_OFF_T offset = (SMB_OFF_T)u_offset;
 548         SMB_OFF_T count = (SMB_OFF_T)u_count;
 549
 550         /*
 551          * For the type of system we are, attempt to
 552          * find the maximum positive lock offset as an SMB_OFF_T.
 553          */
 554
 555 #if defined(MAX_POSITIVE_LOCK_OFFSET) /* Some systems have arbitrary limits. */
 556
 557         SMB_OFF_T max_positive_lock_offset = (MAX_POSITIVE_LOCK_OFFSET);
 558
 559 #elif defined(LARGE_SMB_OFF_T) && !defined(HAVE_BROKEN_FCNTL64_LOCKS)
 560
 561         /*
 562          * In this case SMB_OFF_T is 64 bits,
 563          * and the underlying system can handle 64 bit signed locks.
 564          */
 565
 566     SMB_OFF_T mask2 = ((SMB_OFF_T)0x4) << (SMB_OFF_T_BITS-4);
 567     SMB_OFF_T mask = (mask2<<1);
 568     SMB_OFF_T max_positive_lock_offset = ~mask;
 569
 570 #else /* !LARGE_SMB_OFF_T || HAVE_BROKEN_FCNTL64_LOCKS */
 571
 572         /*
 573          * In this case either SMB_OFF_T is 32 bits,
 574          * or the underlying system cannot handle 64 bit signed locks.
 575          * All offsets & counts must be 2^31 or less.
 576          */
 577
 578     SMB_OFF_T max_positive_lock_offset = 0x7FFFFFFF;
 579
 580 #endif /* !LARGE_SMB_OFF_T || HAVE_BROKEN_FCNTL64_LOCKS */
 581
 582         /*
 583          * POSIX locks of length zero mean lock to end-of-file.
 584          * Win32 locks of length zero are point probes. Ignore
 585          * any Win32 locks of length zero. JRA.
 586          */
 587
 588         if (count == (SMB_OFF_T)0) {
 589                 DEBUG(10,("posix_lock_in_range: count = 0, ignoring.\n"));
 590                 return False;
 591         }
 592
 593         /*
 594          * If the given offset was > max_positive_lock_offset then we cannot map this at all
 595          * ignore this lock.
 596          */
 597
 598         if (u_offset & ~((SMB_BIG_UINT)max_positive_lock_offset)) {
 599                 DEBUG(10,("posix_lock_in_range: (offset = %.0f) offset > %.0f and we cannot handle this. Ignoring lock.\n",
 600                                 (double)u_offset, (double)((SMB_BIG_UINT)max_positive_lock_offset) ));
 601                 return False;
 602         }
 603
 604         /*
 605          * We must truncate the count to less than max_positive_lock_offset.
 606          */
 607
 608         if (u_count & ~((SMB_BIG_UINT)max_positive_lock_offset))
 609                 count = max_positive_lock_offset;
 610
 611         /*
 612          * Truncate count to end at max lock offset.
 613          */
 614
 615         if (offset + count < 0 || offset + count > max_positive_lock_offset)
 616                 count = max_positive_lock_offset - offset;
 617
 618         /*
 619          * If we ate all the count, ignore this lock.
 620          */
 621
 622         if (count == 0) {
 623                 DEBUG(10,("posix_lock_in_range: Count = 0. Ignoring lock u_offset = %.0f, u_count = %.0f\n",
 624                                 (double)u_offset, (double)u_count ));
 625                 return False;
 626         }
 627
 628         /*
 629          * The mapping was successful.
 630          */
 631
 632         DEBUG(10,("posix_lock_in_range: offset_out = %.0f, count_out = %.0f\n",
 633                         (double)offset, (double)count ));
 634
 635         *offset_out = offset;
 636         *count_out = count;
 637
 638         return True;
 639 }
 640
 641 /****************************************************************************
 642  Actual function that does POSIX locks. Copes with 64 -> 32 bit cruft and
 643  broken NFS implementations.
 644 ****************************************************************************/
 645
 646 static BOOL posix_fcntl_lock(files_struct *fsp, int op, SMB_OFF_T offset, SMB_OFF_T count, int type)
 647 {
 648         int ret;
 649
 650         DEBUG(8,("posix_fcntl_lock %d %d %.0f %.0f %d\n",fsp->fd,op,(double)offset,(double)count,type));
 651
 652         ret = SMB_VFS_LOCK(fsp,fsp->fd,op,offset,count,type);
 653
 654         if (!ret && ((errno == EFBIG) || (errno == ENOLCK) || (errno ==  EINVAL))) {
 655
 656                 DEBUG(0,("posix_fcntl_lock: WARNING: lock request at offset %.0f, length %.0f returned\n",
 657                                         (double)offset,(double)count));
 658                 DEBUG(0,("an %s error. This can happen when using 64 bit lock offsets\n", strerror(errno)));
 659                 DEBUG(0,("on 32 bit NFS mounted file systems.\n"));
 660
 661                 /*
 662                  * If the offset is > 0x7FFFFFFF then this will cause problems on
 663                  * 32 bit NFS mounted filesystems. Just ignore it.
 664                  */
 665
 666                 if (offset & ~((SMB_OFF_T)0x7fffffff)) {
 667                         DEBUG(0,("Offset greater than 31 bits. Returning success.\n"));
 668                         return True;
 669                 }
 670
 671                 if (count & ~((SMB_OFF_T)0x7fffffff)) {
 672                         /* 32 bit NFS file system, retry with smaller offset */
 673                         DEBUG(0,("Count greater than 31 bits - retrying with 31 bit truncated length.\n"));
 674                         errno = 0;
 675                         count &= 0x7fffffff;
 676                         ret = SMB_VFS_LOCK(fsp,fsp->fd,op,offset,count,type);
 677                 }
 678         }
 679
 680         DEBUG(8,("posix_fcntl_lock: Lock call %s\n", ret ? "successful" : "failed"));
 681
 682         return ret;
 683 }
 684
 685 /****************************************************************************
 686  POSIX function to see if a file region is locked. Returns True if the
 687  region is locked, False otherwise.
 688 ****************************************************************************/
 689
 690 BOOL is_posix_locked(files_struct *fsp, SMB_BIG_UINT u_offset, SMB_BIG_UINT u_count, enum brl_type lock_type)
 691 {
 692         SMB_OFF_T offset;
 693         SMB_OFF_T count;
 694         int posix_lock_type = map_posix_lock_type(fsp,lock_type);
 695
 696         DEBUG(10,("is_posix_locked: File %s, offset = %.0f, count = %.0f, type = %s\n",
 697                         fsp->fsp_name, (double)u_offset, (double)u_count, posix_lock_type_name(lock_type) ));
 698
 699         /*
 700          * If the requested lock won't fit in the POSIX range, we will
 701          * never set it, so presume it is not locked.
 702          */
 703
 704         if(!posix_lock_in_range(&offset, &count, u_offset, u_count))
 705                 return False;
 706
 707         /*
 708          * Note that most UNIX's can *test* for a write lock on
 709          * a read-only fd, just not *set* a write lock on a read-only
 710          * fd. So we don't need to use map_lock_type here.
 711          */
 712
 713         return posix_fcntl_lock(fsp,SMB_F_GETLK,offset,count,posix_lock_type);
 714 }
 715
 716 /*
 717  * Structure used when splitting a lock range
 718  * into a POSIX lock range. Doubly linked list.
 719  */
 720
 721 struct lock_list {
 722     struct lock_list *next;
 723     struct lock_list *prev;
 724     SMB_OFF_T start;
 725     SMB_OFF_T size;
 726 };
 727
 728 /****************************************************************************
 729  Create a list of lock ranges that don't overlap a given range. Used in calculating
 730  POSIX locks and unlocks. This is a difficult function that requires ASCII art to
 731  understand it :-).
 732 ****************************************************************************/
 733
 734 static struct lock_list *posix_lock_list(TALLOC_CTX *ctx, struct lock_list *lhead, files_struct *fsp)
 735 {
 736         TDB_DATA kbuf = locking_key_fsp(fsp);
 737         TDB_DATA dbuf;
 738         struct posix_lock *locks;
 739         size_t num_locks, i;
 740
 741         dbuf.dptr = NULL;
 742
 743         dbuf = tdb_fetch(posix_lock_tdb, kbuf);
 744
 745         if (!dbuf.dptr)
 746                 return lhead;
 747
 748         locks = (struct posix_lock *)dbuf.dptr;
 749         num_locks = (size_t)(dbuf.dsize / sizeof(*locks));
 750
 751         /*
 752          * Check the current lock list on this dev/inode pair.
 753          * Quit if the list is deleted.
 754          */
 755
 756         DEBUG(10,("posix_lock_list: curr: start=%.0f,size=%.0f\n",
 757                 (double)lhead->start, (double)lhead->size ));
 758
 759         for (i=0; i<num_locks && lhead; i++) {
 760
 761                 struct posix_lock *lock = &locks[i];
 762                 struct lock_list *l_curr;
 763
 764                 /*
 765                  * Walk the lock list, checking for overlaps. Note that
 766                  * the lock list can expand within this loop if the current
 767                  * range being examined needs to be split.
 768                  */
 769
 770                 for (l_curr = lhead; l_curr;) {
 771
 772                         DEBUG(10,("posix_lock_list: lock: fd=%d: start=%.0f,size=%.0f:type=%s", lock->fd,
 773                                 (double)lock->start, (double)lock->size, posix_lock_type_name(lock->lock_type) ));
 774
 775                         if ( (l_curr->start >= (lock->start + lock->size)) ||
 776                                  (lock->start >= (l_curr->start + l_curr->size))) {
 777
 778                                 /* No overlap with this lock - leave this range alone. */
 779 /*********************************************
 780                                              +---------+
 781                                              | l_curr  |
 782                                              +---------+
 783                                 +-------+
 784                                 | lock  |
 785                                 +-------+
 786 OR....
 787              +---------+
 788              |  l_curr |
 789              +---------+
 790 **********************************************/
 791
 792                                 DEBUG(10,("no overlap case.\n" ));
 793
 794                                 l_curr = l_curr->next;
 795
 796                         } else if ( (l_curr->start >= lock->start) &&
 797                                                 (l_curr->start + l_curr->size <= lock->start + lock->size) ) {
 798
 799                                 /*
 800                                  * This unlock is completely overlapped by this existing lock range
 801                                  * and thus should have no effect (not be unlocked). Delete it from the list.
 802                                  */
 803 /*********************************************
 804                 +---------+
 805                 |  l_curr |
 806                 +---------+
 807         +---------------------------+
 808         |       lock                |
 809         +---------------------------+
 810 **********************************************/
 811                                 /* Save the next pointer */
 812                                 struct lock_list *ul_next = l_curr->next;
 813
 814                                 DEBUG(10,("delete case.\n" ));
 815
 816                                 DLIST_REMOVE(lhead, l_curr);
 817                                 if(lhead == NULL)
 818                                         break; /* No more list... */
 819
 820                                 l_curr = ul_next;
 821
 822                         } else if ( (l_curr->start >= lock->start) &&
 823                                                 (l_curr->start < lock->start + lock->size) &&
 824                                                 (l_curr->start + l_curr->size > lock->start + lock->size) ) {
 825
 826                                 /*
 827                                  * This unlock overlaps the existing lock range at the high end.
 828                                  * Truncate by moving start to existing range end and reducing size.
 829                                  */
 830 /*********************************************
 831                 +---------------+
 832                 |  l_curr       |
 833                 +---------------+
 834         +---------------+
 835         |    lock       |
 836         +---------------+
 837 BECOMES....
 838                         +-------+
 839                         | l_curr|
 840                         +-------+
 841 **********************************************/
 842
 843                                 l_curr->size = (l_curr->start + l_curr->size) - (lock->start + lock->size);
 844                                 l_curr->start = lock->start + lock->size;
 845
 846                                 DEBUG(10,("truncate high case: start=%.0f,size=%.0f\n",
 847                                                                 (double)l_curr->start, (double)l_curr->size ));
 848
 849                                 l_curr = l_curr->next;
 850
 851                         } else if ( (l_curr->start < lock->start) &&
 852                                                 (l_curr->start + l_curr->size > lock->start) &&
 853                                                 (l_curr->start + l_curr->size <= lock->start + lock->size) ) {
 854
 855                                 /*
 856                                  * This unlock overlaps the existing lock range at the low end.
 857                                  * Truncate by reducing size.
 858                                  */
 859 /*********************************************
 860    +---------------+
 861    |  l_curr       |
 862    +---------------+
 863            +---------------+
 864            |    lock       |
 865            +---------------+
 866 BECOMES....
 867    +-------+
 868    | l_curr|
 869    +-------+
 870 **********************************************/
 871
 872                                 l_curr->size = lock->start - l_curr->start;
 873
 874                                 DEBUG(10,("truncate low case: start=%.0f,size=%.0f\n",
 875                                                                 (double)l_curr->start, (double)l_curr->size ));
 876
 877                                 l_curr = l_curr->next;
 878
 879                         } else if ( (l_curr->start < lock->start) &&
 880                                                 (l_curr->start + l_curr->size > lock->start + lock->size) ) {
 881                                 /*
 882                                  * Worst case scenario. Unlock request completely overlaps an existing
 883                                  * lock range. Split the request into two, push the new (upper) request
 884                                  * into the dlink list, and continue with the entry after ul_new (as we
 885                                  * know that ul_new will not overlap with this lock).
 886                                  */
 887 /*********************************************
 888         +---------------------------+
 889         |        l_curr             |
 890         +---------------------------+
 891                 +---------+
 892                 | lock    |
 893                 +---------+
 894 BECOMES.....
 895         +-------+         +---------+
 896         | l_curr|         | l_new   |
 897         +-------+         +---------+
 898 **********************************************/
 899                                 struct lock_list *l_new = TALLOC_P(ctx, struct lock_list);
 900
 901                                 if(l_new == NULL) {
 902                                         DEBUG(0,("posix_lock_list: talloc fail.\n"));
 903                                         return NULL; /* The talloc_destroy takes care of cleanup. */
 904                                 }
 905
 906                                 ZERO_STRUCTP(l_new);
 907                                 l_new->start = lock->start + lock->size;
 908                                 l_new->size = l_curr->start + l_curr->size - l_new->start;
 909
 910                                 /* Truncate the l_curr. */
 911                                 l_curr->size = lock->start - l_curr->start;
 912
 913                                 DEBUG(10,("split case: curr: start=%.0f,size=%.0f \
 914 new: start=%.0f,size=%.0f\n", (double)l_curr->start, (double)l_curr->size,
 915                                                                 (double)l_new->start, (double)l_new->size ));
 916
 917                                 /*
 918                                  * Add into the dlink list after the l_curr point - NOT at lhead.
 919                                  * Note we can't use DLINK_ADD here as this inserts at the head of the given list.
 920                                  */
 921
 922                                 l_new->prev = l_curr;
 923                                 l_new->next = l_curr->next;
 924                                 l_curr->next = l_new;
 925
 926                                 /* And move after the link we added. */
 927                                 l_curr = l_new->next;
 928
 929                         } else {
 930
 931                                 /*
 932                                  * This logic case should never happen. Ensure this is the
 933                                  * case by forcing an abort.... Remove in production.
 934                                  */
 935                                 pstring msg;
 936
 937                                 slprintf(msg, sizeof(msg)-1, "logic flaw in cases: l_curr: start = %.0f, size = %.0f : \
 938 lock: start = %.0f, size = %.0f\n", (double)l_curr->start, (double)l_curr->size, (double)lock->start, (double)lock->size );
 939
 940                                 smb_panic(msg);
 941                         }
 942                 } /* end for ( l_curr = lhead; l_curr;) */
 943         } /* end for (i=0; i<num_locks && ul_head; i++) */
 944
 945         SAFE_FREE(dbuf.dptr);
 946
 947         return lhead;
 948 }
 949
 950 /****************************************************************************
 951  POSIX function to acquire a lock. Returns True if the
 952  lock could be granted, False if not.
 953 ****************************************************************************/
 954
 955 BOOL set_posix_lock(files_struct *fsp, SMB_BIG_UINT u_offset, SMB_BIG_UINT u_count, enum brl_type lock_type)
 956 {
 957         SMB_OFF_T offset;
 958         SMB_OFF_T count;
 959         BOOL ret = True;
 960         size_t entry_num = 0;
 961         size_t lock_count;
 962         TALLOC_CTX *l_ctx = NULL;
 963         struct lock_list *llist = NULL;
 964         struct lock_list *ll = NULL;
 965         int posix_lock_type = map_posix_lock_type(fsp,lock_type);
 966
 967         DEBUG(5,("set_posix_lock: File %s, offset = %.0f, count = %.0f, type = %s\n",
 968                         fsp->fsp_name, (double)u_offset, (double)u_count, posix_lock_type_name(lock_type) ));
 969
 970         /*
 971          * If the requested lock won't fit in the POSIX range, we will
 972          * pretend it was successful.
 973          */
 974
 975         if(!posix_lock_in_range(&offset, &count, u_offset, u_count))
 976                 return True;
 977
 978         /*
 979          * Windows is very strange. It allows read locks to be overlayed
 980          * (even over a write lock), but leaves the write lock in force until the first
 981          * unlock. It also reference counts the locks. This means the following sequence :
 982          *
 983          * process1                                      process2
 984          * ------------------------------------------------------------------------
 985          * WRITE LOCK : start = 2, len = 10
 986          *                                            READ LOCK: start =0, len = 10 - FAIL
 987          * READ LOCK : start = 0, len = 14
 988          *                                            READ LOCK: start =0, len = 10 - FAIL
 989          * UNLOCK : start = 2, len = 10
 990          *                                            READ LOCK: start =0, len = 10 - OK
 991          *
 992          * Under POSIX, the same sequence in steps 1 and 2 would not be reference counted, but
 993          * would leave a single read lock over the 0-14 region. In order to
 994          * re-create Windows semantics mapped to POSIX locks, we create multiple TDB
 995          * entries, one for each overlayed lock request. We are guarenteed by the brlock
 996          * semantics that if a write lock is added, then it will be first in the array.
 997          */
 998
 999         if ((l_ctx = talloc_init("set_posix_lock")) == NULL) {
1000                 DEBUG(0,("set_posix_lock: unable to init talloc context.\n"));
1001                 return True; /* Not a fatal error. */
1002         }
1003
1004         if ((ll = TALLOC_P(l_ctx, struct lock_list)) == NULL) {
1005                 DEBUG(0,("set_posix_lock: unable to talloc unlock list.\n"));
1006                 talloc_destroy(l_ctx);
1007                 return True; /* Not a fatal error. */
1008         }
1009
1010         /*
1011          * Create the initial list entry containing the
1012          * lock we want to add.
1013          */
1014
1015         ZERO_STRUCTP(ll);
1016         ll->start = offset;
1017         ll->size = count;
1018
1019         DLIST_ADD(llist, ll);
1020
1021         /*
1022          * The following call calculates if there are any
1023          * overlapping locks held by this process on
1024          * fd's open on the same file and splits this list
1025          * into a list of lock ranges that do not overlap with existing
1026          * POSIX locks.
1027          */
1028
1029         llist = posix_lock_list(l_ctx, llist, fsp);
1030
1031         /*
1032          * Now we have the list of ranges to lock it is safe to add the
1033          * entry into the POSIX lock tdb. We take note of the entry we
1034          * added here in case we have to remove it on POSIX lock fail.
1035          */
1036
1037         if (!add_posix_lock_entry(fsp,offset,count,posix_lock_type,&entry_num)) {
1038                 DEBUG(0,("set_posix_lock: Unable to create posix lock entry !\n"));
1039                 talloc_destroy(l_ctx);
1040                 return False;
1041         }
1042
1043         /*
1044          * Add the POSIX locks on the list of ranges returned.
1045          * As the lock is supposed to be added atomically, we need to
1046          * back out all the locks if any one of these calls fail.
1047          */
1048
1049         for (lock_count = 0, ll = llist; ll; ll = ll->next, lock_count++) {
1050                 offset = ll->start;
1051                 count = ll->size;
1052
1053                 DEBUG(5,("set_posix_lock: Real lock: Type = %s: offset = %.0f, count = %.0f\n",
1054                         posix_lock_type_name(posix_lock_type), (double)offset, (double)count ));
1055
1056                 if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,posix_lock_type)) {
1057                         DEBUG(5,("set_posix_lock: Lock fail !: Type = %s: offset = %.0f, count = %.0f. Errno = %s\n",
1058                                 posix_lock_type_name(posix_lock_type), (double)offset, (double)count, strerror(errno) ));
1059                         ret = False;
1060                         break;
1061                 }
1062         }
1063
1064         if (!ret) {
1065
1066                 /*
1067                  * Back out all the POSIX locks we have on fail.
1068                  */
1069
1070                 for (ll = llist; lock_count; ll = ll->next, lock_count--) {
1071                         offset = ll->start;
1072                         count = ll->size;
1073
1074                         DEBUG(5,("set_posix_lock: Backing out locks: Type = %s: offset = %.0f, count = %.0f\n",
1075                                 posix_lock_type_name(posix_lock_type), (double)offset, (double)count ));
1076
1077                         posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_UNLCK);
1078                 }
1079
1080                 /*
1081                  * Remove the tdb entry for this lock.
1082                  */
1083
1084                 delete_posix_lock_entry_by_index(fsp,entry_num);
1085         }
1086
1087         talloc_destroy(l_ctx);
1088         return ret;
1089 }
1090
1091 /****************************************************************************
1092  POSIX function to release a lock. Returns True if the
1093  lock could be released, False if not.
1094 ****************************************************************************/
1095
1096 BOOL release_posix_lock(files_struct *fsp, SMB_BIG_UINT u_offset, SMB_BIG_UINT u_count)
1097 {
1098         SMB_OFF_T offset;
1099         SMB_OFF_T count;
1100         BOOL ret = True;
1101         TALLOC_CTX *ul_ctx = NULL;
1102         struct lock_list *ulist = NULL;
1103         struct lock_list *ul = NULL;
1104         struct posix_lock deleted_lock;
1105         int num_overlapped_entries;
1106
1107         DEBUG(5,("release_posix_lock: File %s, offset = %.0f, count = %.0f\n",
1108                 fsp->fsp_name, (double)u_offset, (double)u_count ));
1109
1110         /*
1111          * If the requested lock won't fit in the POSIX range, we will
1112          * pretend it was successful.
1113          */
1114
1115         if(!posix_lock_in_range(&offset, &count, u_offset, u_count))
1116                 return True;
1117
1118         /*
1119          * We treat this as one unlock request for POSIX accounting purposes even
1120          * if it may later be split into multiple smaller POSIX unlock ranges.
1121          * num_overlapped_entries is the number of existing locks that have any
1122          * overlap with this unlock request.
1123          */
1124
1125         num_overlapped_entries = delete_posix_lock_entry(fsp, offset, count, &deleted_lock);
1126
1127         if (num_overlapped_entries == -1) {
1128         smb_panic("release_posix_lock: unable find entry to delete !\n");
1129         }
1130
1131         /*
1132          * If num_overlapped_entries is > 0, and the lock_type we just deleted from the tdb was
1133          * a POSIX write lock, then before doing the unlock we need to downgrade
1134          * the POSIX lock to a read lock. This allows any overlapping read locks
1135          * to be atomically maintained.
1136          */
1137
1138         if (num_overlapped_entries > 0 && deleted_lock.lock_type == F_WRLCK) {
1139                 if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_RDLCK)) {
1140                         DEBUG(0,("release_posix_lock: downgrade of lock failed with error %s !\n", strerror(errno) ));
1141                         return False;
1142                 }
1143         }
1144
1145         if ((ul_ctx = talloc_init("release_posix_lock")) == NULL) {
1146                 DEBUG(0,("release_posix_lock: unable to init talloc context.\n"));
1147                 return True; /* Not a fatal error. */
1148         }
1149
1150         if ((ul = TALLOC_P(ul_ctx, struct lock_list)) == NULL) {
1151                 DEBUG(0,("release_posix_lock: unable to talloc unlock list.\n"));
1152                 talloc_destroy(ul_ctx);
1153                 return True; /* Not a fatal error. */
1154         }
1155
1156         /*
1157          * Create the initial list entry containing the
1158          * lock we want to remove.
1159          */
1160
1161         ZERO_STRUCTP(ul);
1162         ul->start = offset;
1163         ul->size = count;
1164
1165         DLIST_ADD(ulist, ul);
1166
1167         /*
1168          * The following call calculates if there are any
1169          * overlapping locks held by this process on
1170          * fd's open on the same file and creates a
1171          * list of unlock ranges that will allow
1172          * POSIX lock ranges to remain on the file whilst the
1173          * unlocks are performed.
1174          */
1175
1176         ulist = posix_lock_list(ul_ctx, ulist, fsp);
1177
1178         /*
1179          * Release the POSIX locks on the list of ranges returned.
1180          */
1181
1182         for(; ulist; ulist = ulist->next) {
1183                 offset = ulist->start;
1184                 count = ulist->size;
1185
1186                 DEBUG(5,("release_posix_lock: Real unlock: offset = %.0f, count = %.0f\n",
1187                         (double)offset, (double)count ));
1188
1189                 if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_UNLCK))
1190                         ret = False;
1191         }
1192
1193         talloc_destroy(ul_ctx);
1194
1195         return ret;
1196 }
1197
1198 /****************************************************************************
1199  Remove all lock entries for a specific dev/inode pair from the tdb.
1200 ****************************************************************************/
1201
1202 static void delete_posix_lock_entries(files_struct *fsp)
1203 {
1204         TDB_DATA kbuf = locking_key_fsp(fsp);
1205
1206         if (tdb_delete(posix_lock_tdb, kbuf) == -1)
1207                 DEBUG(0,("delete_close_entries: tdb_delete fail !\n"));
1208 }
1209
1210 /****************************************************************************
1211  Debug function.
1212 ****************************************************************************/
1213
1214 static void dump_entry(struct posix_lock *pl)
1215 {
1216         DEBUG(10,("entry: start=%.0f, size=%.0f, type=%d, fd=%i\n",
1217                 (double)pl->start, (double)pl->size, (int)pl->lock_type, pl->fd ));
1218 }
1219
1220 /****************************************************************************
1221  Remove any locks on this fd. Called from file_close().
1222 ****************************************************************************/
1223
1224 void posix_locking_close_file(files_struct *fsp)
1225 {
1226         struct posix_lock *entries = NULL;
1227         size_t count, i;
1228
1229         /*
1230          * Optimization for the common case where we are the only
1231          * opener of a file. If all fd entries are our own, we don't
1232          * need to explicitly release all the locks via the POSIX functions,
1233          * we can just remove all the entries in the tdb and allow the
1234          * close to remove the real locks.
1235          */
1236
1237         count = get_posix_lock_entries(fsp, &entries);
1238
1239         if (count == 0) {
1240                 DEBUG(10,("posix_locking_close_file: file %s has no outstanding locks.\n", fsp->fsp_name ));
1241                 return;
1242         }
1243
1244         for (i = 0; i < count; i++) {
1245                 if (entries[i].fd != fsp->fd )
1246                         break;
1247
1248                 dump_entry(&entries[i]);
1249         }
1250
1251         if (i == count) {
1252                 /* All locks are ours. */
1253                 DEBUG(10,("posix_locking_close_file: file %s has %u outstanding locks, but all on one fd.\n",
1254                         fsp->fsp_name, (unsigned int)count ));
1255                 SAFE_FREE(entries);
1256                 delete_posix_lock_entries(fsp);
1257                 return;
1258         }
1259
1260         /*
1261          * Difficult case. We need to delete all our locks, whilst leaving
1262          * all other POSIX locks in place.
1263          */
1264
1265         for (i = 0; i < count; i++) {
1266                 struct posix_lock *pl = &entries[i];
1267                 if (pl->fd == fsp->fd)
1268                         release_posix_lock(fsp, (SMB_BIG_UINT)pl->start, (SMB_BIG_UINT)pl->size );
1269         }
1270         SAFE_FREE(entries);
1271 }
1272
1273 /*******************************************************************
1274  Create the in-memory POSIX lock databases.
1275 ********************************************************************/
1276
1277 BOOL posix_locking_init(int read_only)
1278 {
1279         if (posix_lock_tdb && posix_pending_close_tdb)
1280                 return True;
1281
1282         if (!posix_lock_tdb)
1283                 posix_lock_tdb = tdb_open_log(NULL, 0, TDB_INTERNAL,
1284                                           read_only?O_RDONLY:(O_RDWR|O_CREAT), 0644);
1285         if (!posix_lock_tdb) {
1286                 DEBUG(0,("Failed to open POSIX byte range locking database.\n"));
1287                 return False;
1288         }
1289         if (!posix_pending_close_tdb)
1290                 posix_pending_close_tdb = tdb_open_log(NULL, 0, TDB_INTERNAL,
1291                                                    read_only?O_RDONLY:(O_RDWR|O_CREAT), 0644);
1292         if (!posix_pending_close_tdb) {
1293                 DEBUG(0,("Failed to open POSIX pending close database.\n"));
1294                 return False;
1295         }
1296
1297         return True;
1298 }
1299
1300 /*******************************************************************
1301  Delete the in-memory POSIX lock databases.
1302 ********************************************************************/
1303
1304 BOOL posix_locking_end(void)
1305 {
1306     if (posix_lock_tdb && tdb_close(posix_lock_tdb) != 0)
1307                 return False;
1308     if (posix_pending_close_tdb && tdb_close(posix_pending_close_tdb) != 0)
1309                 return False;
1310         return True;
1311 }