lib/tdb/common/transaction.c

   1  /*
   2    Unix SMB/CIFS implementation.
   3
   4    trivial database library
   5
   6    Copyright (C) Andrew Tridgell              2005
   7
   8      ** NOTE! The following LGPL license applies to the tdb
   9      ** library. This does NOT imply that all of Samba is released
  10      ** under the LGPL
  11
  12    This library is free software; you can redistribute it and/or
  13    modify it under the terms of the GNU Lesser General Public
  14    License as published by the Free Software Foundation; either
  15    version 3 of the License, or (at your option) any later version.
  16
  17    This library is distributed in the hope that it will be useful,
  18    but WITHOUT ANY WARRANTY; without even the implied warranty of
  19    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20    Lesser General Public License for more details.
  21
  22    You should have received a copy of the GNU Lesser General Public
  23    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  24 */
  25
  26 #include "tdb_private.h"
  27
  28 /*
  29   transaction design:
  30
  31   - only allow a single transaction at a time per database. This makes
  32     using the transaction API simpler, as otherwise the caller would
  33     have to cope with temporary failures in transactions that conflict
  34     with other current transactions
  35
  36   - keep the transaction recovery information in the same file as the
  37     database, using a special 'transaction recovery' record pointed at
  38     by the header. This removes the need for extra journal files as
  39     used by some other databases
  40
  41   - dynamically allocated the transaction recover record, re-using it
  42     for subsequent transactions. If a larger record is needed then
  43     tdb_free() the old record to place it on the normal tdb freelist
  44     before allocating the new record
  45
  46   - during transactions, keep a linked list of writes all that have
  47     been performed by intercepting all tdb_write() calls. The hooked
  48     transaction versions of tdb_read() and tdb_write() check this
  49     linked list and try to use the elements of the list in preference
  50     to the real database.
  51
  52   - don't allow any locks to be held when a transaction starts,
  53     otherwise we can end up with deadlock (plus lack of lock nesting
  54     in posix locks would mean the lock is lost)
  55
  56   - if the caller gains a lock during the transaction but doesn't
  57     release it then fail the commit
  58
  59   - allow for nested calls to tdb_transaction_start(), re-using the
  60     existing transaction record. If the inner transaction is cancelled
  61     then a subsequent commit will fail
  62
  63   - keep a mirrored copy of the tdb hash chain heads to allow for the
  64     fast hash heads scan on traverse, updating the mirrored copy in
  65     the transaction version of tdb_write
  66
  67   - allow callers to mix transaction and non-transaction use of tdb,
  68     although once a transaction is started then an exclusive lock is
  69     gained until the transaction is committed or cancelled
  70
  71   - the commit stategy involves first saving away all modified data
  72     into a linearised buffer in the transaction recovery area, then
  73     marking the transaction recovery area with a magic value to
  74     indicate a valid recovery record. In total 4 fsync/msync calls are
  75     needed per commit to prevent race conditions. It might be possible
  76     to reduce this to 3 or even 2 with some more work.
  77
  78   - check for a valid recovery record on open of the tdb, while the
  79     global lock is held. Automatically recover from the transaction
  80     recovery area if needed, then continue with the open as
  81     usual. This allows for smooth crash recovery with no administrator
  82     intervention.
  83
  84   - if TDB_NOSYNC is passed to flags in tdb_open then transactions are
  85     still available, but no transaction recovery area is used and no
  86     fsync/msync calls are made.
  87
  88   - if TDB_ALLOW_NESTING is passed to flags in tdb open, or added using
  89     tdb_add_flags() transaction is enabled.
  90     The default is that transaction nesting is not allowed and an attempt
  91     to create a nested transaction will fail with TDB_ERR_NESTING.
  92
  93     Beware. when transactions are nested a transaction successfully
  94     completed with tdb_transaction_commit() can be silently unrolled later.
  95 */
  96
  97
  98 /*
  99   hold the context of any current transaction
 100 */
 101 struct tdb_transaction {
 102         /* we keep a mirrored copy of the tdb hash heads here so
 103            tdb_next_hash_chain() can operate efficiently */
 104         uint32_t *hash_heads;
 105
 106         /* the original io methods - used to do IOs to the real db */
 107         const struct tdb_methods *io_methods;
 108
 109         /* the list of transaction blocks. When a block is first
 110            written to, it gets created in this list */
 111         uint8_t **blocks;
 112         uint32_t num_blocks;
 113         uint32_t block_size;      /* bytes in each block */
 114         uint32_t last_block_size; /* number of valid bytes in the last block */
 115
 116         /* non-zero when an internal transaction error has
 117            occurred. All write operations will then fail until the
 118            transaction is ended */
 119         int transaction_error;
 120
 121         /* when inside a transaction we need to keep track of any
 122            nested tdb_transaction_start() calls, as these are allowed,
 123            but don't create a new transaction */
 124         int nesting;
 125
 126         /* set when a prepare has already occurred */
 127         bool prepared;
 128         tdb_off_t magic_offset;
 129
 130         /* old file size before transaction */
 131         tdb_len_t old_map_size;
 132
 133         /* we should re-pack on commit */
 134         bool need_repack;
 135 };
 136
 137
 138 /*
 139   read while in a transaction. We need to check first if the data is in our list
 140   of transaction elements, then if not do a real read
 141 */
 142 static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
 143                             tdb_len_t len, int cv)
 144 {
 145         uint32_t blk;
 146
 147         /* break it down into block sized ops */
 148         while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
 149                 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
 150                 if (transaction_read(tdb, off, buf, len2, cv) != 0) {
 151                         return -1;
 152                 }
 153                 len -= len2;
 154                 off += len2;
 155                 buf = (void *)(len2 + (char *)buf);
 156         }
 157
 158         if (len == 0) {
 159                 return 0;
 160         }
 161
 162         blk = off / tdb->transaction->block_size;
 163
 164         /* see if we have it in the block list */
 165         if (tdb->transaction->num_blocks <= blk ||
 166             tdb->transaction->blocks[blk] == NULL) {
 167                 /* nope, do a real read */
 168                 if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) {
 169                         goto fail;
 170                 }
 171                 return 0;
 172         }
 173
 174         /* it is in the block list. Now check for the last block */
 175         if (blk == tdb->transaction->num_blocks-1) {
 176                 if (len > tdb->transaction->last_block_size) {
 177                         goto fail;
 178                 }
 179         }
 180
 181         /* now copy it out of this block */
 182         memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
 183         if (cv) {
 184                 tdb_convert(buf, len);
 185         }
 186         return 0;
 187
 188 fail:
 189         TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
 190         tdb->ecode = TDB_ERR_IO;
 191         tdb->transaction->transaction_error = 1;
 192         return -1;
 193 }
 194
 195
 196 /*
 197   write while in a transaction
 198 */
 199 static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
 200                              const void *buf, tdb_len_t len)
 201 {
 202         uint32_t blk;
 203
 204         /* Only a commit is allowed on a prepared transaction */
 205         if (tdb->transaction->prepared) {
 206                 tdb->ecode = TDB_ERR_EINVAL;
 207                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: transaction already prepared, write not allowed\n"));
 208                 tdb->transaction->transaction_error = 1;
 209                 return -1;
 210         }
 211
 212         /* if the write is to a hash head, then update the transaction
 213            hash heads */
 214         if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
 215             off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) {
 216                 uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t);
 217                 memcpy(&tdb->transaction->hash_heads[chain], buf, len);
 218         }
 219
 220         /* break it up into block sized chunks */
 221         while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
 222                 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
 223                 if (transaction_write(tdb, off, buf, len2) != 0) {
 224                         return -1;
 225                 }
 226                 len -= len2;
 227                 off += len2;
 228                 if (buf != NULL) {
 229                         buf = (const void *)(len2 + (const char *)buf);
 230                 }
 231         }
 232
 233         if (len == 0) {
 234                 return 0;
 235         }
 236
 237         blk = off / tdb->transaction->block_size;
 238         off = off % tdb->transaction->block_size;
 239
 240         if (tdb->transaction->num_blocks <= blk) {
 241                 uint8_t **new_blocks;
 242                 /* expand the blocks array */
 243                 if (tdb->transaction->blocks == NULL) {
 244                         new_blocks = (uint8_t **)malloc(
 245                                 (blk+1)*sizeof(uint8_t *));
 246                 } else {
 247                         new_blocks = (uint8_t **)realloc(
 248                                 tdb->transaction->blocks,
 249                                 (blk+1)*sizeof(uint8_t *));
 250                 }
 251                 if (new_blocks == NULL) {
 252                         tdb->ecode = TDB_ERR_OOM;
 253                         goto fail;
 254                 }
 255                 memset(&new_blocks[tdb->transaction->num_blocks], 0,
 256                        (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
 257                 tdb->transaction->blocks = new_blocks;
 258                 tdb->transaction->num_blocks = blk+1;
 259                 tdb->transaction->last_block_size = 0;
 260         }
 261
 262         /* allocate and fill a block? */
 263         if (tdb->transaction->blocks[blk] == NULL) {
 264                 tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
 265                 if (tdb->transaction->blocks[blk] == NULL) {
 266                         tdb->ecode = TDB_ERR_OOM;
 267                         tdb->transaction->transaction_error = 1;
 268                         return -1;
 269                 }
 270                 if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
 271                         tdb_len_t len2 = tdb->transaction->block_size;
 272                         if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
 273                                 len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
 274                         }
 275                         if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size,
 276                                                                    tdb->transaction->blocks[blk],
 277                                                                    len2, 0) != 0) {
 278                                 SAFE_FREE(tdb->transaction->blocks[blk]);
 279                                 tdb->ecode = TDB_ERR_IO;
 280                                 goto fail;
 281                         }
 282                         if (blk == tdb->transaction->num_blocks-1) {
 283                                 tdb->transaction->last_block_size = len2;
 284                         }
 285                 }
 286         }
 287
 288         /* overwrite part of an existing block */
 289         if (buf == NULL) {
 290                 memset(tdb->transaction->blocks[blk] + off, 0, len);
 291         } else {
 292                 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
 293         }
 294         if (blk == tdb->transaction->num_blocks-1) {
 295                 if (len + off > tdb->transaction->last_block_size) {
 296                         tdb->transaction->last_block_size = len + off;
 297                 }
 298         }
 299
 300         return 0;
 301
 302 fail:
 303         TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n",
 304                  (blk*tdb->transaction->block_size) + off, len));
 305         tdb->transaction->transaction_error = 1;
 306         return -1;
 307 }
 308
 309
 310 /*
 311   write while in a transaction - this varient never expands the transaction blocks, it only
 312   updates existing blocks. This means it cannot change the recovery size
 313 */
 314 static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
 315                                       const void *buf, tdb_len_t len)
 316 {
 317         uint32_t blk;
 318
 319         /* break it up into block sized chunks */
 320         while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
 321                 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
 322                 if (transaction_write_existing(tdb, off, buf, len2) != 0) {
 323                         return -1;
 324                 }
 325                 len -= len2;
 326                 off += len2;
 327                 if (buf != NULL) {
 328                         buf = (const void *)(len2 + (const char *)buf);
 329                 }
 330         }
 331
 332         if (len == 0) {
 333                 return 0;
 334         }
 335
 336         blk = off / tdb->transaction->block_size;
 337         off = off % tdb->transaction->block_size;
 338
 339         if (tdb->transaction->num_blocks <= blk ||
 340             tdb->transaction->blocks[blk] == NULL) {
 341                 return 0;
 342         }
 343
 344         if (blk == tdb->transaction->num_blocks-1 &&
 345             off + len > tdb->transaction->last_block_size) {
 346                 if (off >= tdb->transaction->last_block_size) {
 347                         return 0;
 348                 }
 349                 len = tdb->transaction->last_block_size - off;
 350         }
 351
 352         /* overwrite part of an existing block */
 353         memcpy(tdb->transaction->blocks[blk] + off, buf, len);
 354
 355         return 0;
 356 }
 357
 358
 359 /*
 360   accelerated hash chain head search, using the cached hash heads
 361 */
 362 static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
 363 {
 364         uint32_t h = *chain;
 365         for (;h < tdb->header.hash_size;h++) {
 366                 /* the +1 takes account of the freelist */
 367                 if (0 != tdb->transaction->hash_heads[h+1]) {
 368                         break;
 369                 }
 370         }
 371         (*chain) = h;
 372 }
 373
 374 /*
 375   out of bounds check during a transaction
 376 */
 377 static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
 378 {
 379         if (len <= tdb->map_size) {
 380                 return 0;
 381         }
 382         return TDB_ERRCODE(TDB_ERR_IO, -1);
 383 }
 384
 385 /*
 386   transaction version of tdb_expand().
 387 */
 388 static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
 389                                    tdb_off_t addition)
 390 {
 391         /* add a write to the transaction elements, so subsequent
 392            reads see the zero data */
 393         if (transaction_write(tdb, size, NULL, addition) != 0) {
 394                 return -1;
 395         }
 396
 397         tdb->transaction->need_repack = true;
 398
 399         return 0;
 400 }
 401
 402 /*
 403   brlock during a transaction - ignore them
 404 */
 405 static int transaction_brlock(struct tdb_context *tdb, tdb_off_t offset,
 406                               int rw_type, int lck_type, int probe, size_t len)
 407 {
 408         return 0;
 409 }
 410
 411 static const struct tdb_methods transaction_methods = {
 412         transaction_read,
 413         transaction_write,
 414         transaction_next_hash_chain,
 415         transaction_oob,
 416         transaction_expand_file,
 417         transaction_brlock
 418 };
 419
 420
 421 /*
 422   start a tdb transaction. No token is returned, as only a single
 423   transaction is allowed to be pending per tdb_context
 424 */
 425 int tdb_transaction_start(struct tdb_context *tdb)
 426 {
 427         /* some sanity checks */
 428         if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
 429                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
 430                 tdb->ecode = TDB_ERR_EINVAL;
 431                 return -1;
 432         }
 433
 434         /* cope with nested tdb_transaction_start() calls */
 435         if (tdb->transaction != NULL) {
 436                 if (!(tdb->flags & TDB_ALLOW_NESTING)) {
 437                         tdb->ecode = TDB_ERR_NESTING;
 438                         return -1;
 439                 }
 440                 tdb->transaction->nesting++;
 441                 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
 442                          tdb->transaction->nesting));
 443                 return 0;
 444         }
 445
 446         if (tdb->num_locks != 0 || tdb->global_lock.count) {
 447                 /* the caller must not have any locks when starting a
 448                    transaction as otherwise we'll be screwed by lack
 449                    of nested locks in posix */
 450                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
 451                 tdb->ecode = TDB_ERR_LOCK;
 452                 return -1;
 453         }
 454
 455         if (tdb->travlocks.next != NULL) {
 456                 /* you cannot use transactions inside a traverse (although you can use
 457                    traverse inside a transaction) as otherwise you can end up with
 458                    deadlock */
 459                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
 460                 tdb->ecode = TDB_ERR_LOCK;
 461                 return -1;
 462         }
 463
 464         tdb->transaction = (struct tdb_transaction *)
 465                 calloc(sizeof(struct tdb_transaction), 1);
 466         if (tdb->transaction == NULL) {
 467                 tdb->ecode = TDB_ERR_OOM;
 468                 return -1;
 469         }
 470
 471         /* a page at a time seems like a reasonable compromise between compactness and efficiency */
 472         tdb->transaction->block_size = tdb->page_size;
 473
 474         /* get the transaction write lock. This is a blocking lock. As
 475            discussed with Volker, there are a number of ways we could
 476            make this async, which we will probably do in the future */
 477         if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
 478                 SAFE_FREE(tdb->transaction->blocks);
 479                 SAFE_FREE(tdb->transaction);
 480                 return -1;
 481         }
 482
 483         /* get a read lock from the freelist to the end of file. This
 484            is upgraded to a write lock during the commit */
 485         if (tdb_brlock(tdb, FREELIST_TOP, F_RDLCK, F_SETLKW, 0, 0) == -1) {
 486                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
 487                 tdb->ecode = TDB_ERR_LOCK;
 488                 goto fail;
 489         }
 490
 491         /* setup a copy of the hash table heads so the hash scan in
 492            traverse can be fast */
 493         tdb->transaction->hash_heads = (uint32_t *)
 494                 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
 495         if (tdb->transaction->hash_heads == NULL) {
 496                 tdb->ecode = TDB_ERR_OOM;
 497                 goto fail;
 498         }
 499         if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
 500                                    TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
 501                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
 502                 tdb->ecode = TDB_ERR_IO;
 503                 goto fail;
 504         }
 505
 506         /* make sure we know about any file expansions already done by
 507            anyone else */
 508         tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
 509         tdb->transaction->old_map_size = tdb->map_size;
 510
 511         /* finally hook the io methods, replacing them with
 512            transaction specific methods */
 513         tdb->transaction->io_methods = tdb->methods;
 514         tdb->methods = &transaction_methods;
 515
 516         /* Trace at the end, so we get sequence number correct. */
 517         tdb_trace(tdb, "tdb_transaction_start");
 518         return 0;
 519
 520 fail:
 521         tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
 522         tdb_transaction_unlock(tdb);
 523         SAFE_FREE(tdb->transaction->blocks);
 524         SAFE_FREE(tdb->transaction->hash_heads);
 525         SAFE_FREE(tdb->transaction);
 526         return -1;
 527 }
 528
 529
 530 /*
 531   sync to disk
 532 */
 533 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
 534 {
 535         if (tdb->flags & TDB_NOSYNC) {
 536                 return 0;
 537         }
 538
 539         if (fsync(tdb->fd) != 0) {
 540                 tdb->ecode = TDB_ERR_IO;
 541                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
 542                 return -1;
 543         }
 544 #ifdef MS_SYNC
 545         if (tdb->map_ptr) {
 546                 tdb_off_t moffset = offset & ~(tdb->page_size-1);
 547                 if (msync(moffset + (char *)tdb->map_ptr,
 548                           length + (offset - moffset), MS_SYNC) != 0) {
 549                         tdb->ecode = TDB_ERR_IO;
 550                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
 551                                  strerror(errno)));
 552                         return -1;
 553                 }
 554         }
 555 #endif
 556         return 0;
 557 }
 558
 559
 560 int _tdb_transaction_cancel(struct tdb_context *tdb)
 561 {
 562         int i, ret = 0;
 563
 564         if (tdb->transaction == NULL) {
 565                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
 566                 return -1;
 567         }
 568
 569         if (tdb->transaction->nesting != 0) {
 570                 tdb->transaction->transaction_error = 1;
 571                 tdb->transaction->nesting--;
 572                 return 0;
 573         }
 574
 575         tdb->map_size = tdb->transaction->old_map_size;
 576
 577         /* free all the transaction blocks */
 578         for (i=0;i<tdb->transaction->num_blocks;i++) {
 579                 if (tdb->transaction->blocks[i] != NULL) {
 580                         free(tdb->transaction->blocks[i]);
 581                 }
 582         }
 583         SAFE_FREE(tdb->transaction->blocks);
 584
 585         if (tdb->transaction->magic_offset) {
 586                 const struct tdb_methods *methods = tdb->transaction->io_methods;
 587                 uint32_t zero = 0;
 588
 589                 /* remove the recovery marker */
 590                 if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &zero, 4) == -1 ||
 591                 transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
 592                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
 593                         ret = -1;
 594                 }
 595         }
 596
 597         /* remove any global lock created during the transaction */
 598         if (tdb->global_lock.count != 0) {
 599                 tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 4*tdb->header.hash_size);
 600                 tdb->global_lock.count = 0;
 601         }
 602
 603         /* remove any locks created during the transaction */
 604         if (tdb->num_locks != 0) {
 605                 for (i=0;i<tdb->num_lockrecs;i++) {
 606                         tdb_brlock(tdb,FREELIST_TOP+4*tdb->lockrecs[i].list,
 607                                    F_UNLCK,F_SETLKW, 0, 1);
 608                 }
 609                 tdb->num_locks = 0;
 610                 tdb->num_lockrecs = 0;
 611                 SAFE_FREE(tdb->lockrecs);
 612         }
 613
 614         /* restore the normal io methods */
 615         tdb->methods = tdb->transaction->io_methods;
 616
 617         tdb_brlock(tdb, FREELIST_TOP, F_UNLCK, F_SETLKW, 0, 0);
 618         tdb_transaction_unlock(tdb);
 619         SAFE_FREE(tdb->transaction->hash_heads);
 620         SAFE_FREE(tdb->transaction);
 621
 622         return ret;
 623 }
 624
 625 /*
 626   cancel the current transaction
 627 */
 628 int tdb_transaction_cancel(struct tdb_context *tdb)
 629 {
 630         tdb_trace(tdb, "tdb_transaction_cancel");
 631         return _tdb_transaction_cancel(tdb);
 632 }
 633
 634 /*
 635   work out how much space the linearised recovery data will consume
 636 */
 637 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
 638 {
 639         tdb_len_t recovery_size = 0;
 640         int i;
 641
 642         recovery_size = sizeof(uint32_t);
 643         for (i=0;i<tdb->transaction->num_blocks;i++) {
 644                 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
 645                         break;
 646                 }
 647                 if (tdb->transaction->blocks[i] == NULL) {
 648                         continue;
 649                 }
 650                 recovery_size += 2*sizeof(tdb_off_t);
 651                 if (i == tdb->transaction->num_blocks-1) {
 652                         recovery_size += tdb->transaction->last_block_size;
 653                 } else {
 654                         recovery_size += tdb->transaction->block_size;
 655                 }
 656         }
 657
 658         return recovery_size;
 659 }
 660
 661 /*
 662   allocate the recovery area, or use an existing recovery area if it is
 663   large enough
 664 */
 665 static int tdb_recovery_allocate(struct tdb_context *tdb,
 666                                  tdb_len_t *recovery_size,
 667                                  tdb_off_t *recovery_offset,
 668                                  tdb_len_t *recovery_max_size)
 669 {
 670         struct list_struct rec;
 671         const struct tdb_methods *methods = tdb->transaction->io_methods;
 672         tdb_off_t recovery_head;
 673
 674         if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
 675                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
 676                 return -1;
 677         }
 678
 679         rec.rec_len = 0;
 680
 681         if (recovery_head != 0 &&
 682             methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
 683                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
 684                 return -1;
 685         }
 686
 687         *recovery_size = tdb_recovery_size(tdb);
 688
 689         if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
 690                 /* it fits in the existing area */
 691                 *recovery_max_size = rec.rec_len;
 692                 *recovery_offset = recovery_head;
 693                 return 0;
 694         }
 695
 696         /* we need to free up the old recovery area, then allocate a
 697            new one at the end of the file. Note that we cannot use
 698            tdb_allocate() to allocate the new one as that might return
 699            us an area that is being currently used (as of the start of
 700            the transaction) */
 701         if (recovery_head != 0) {
 702                 if (tdb_free(tdb, recovery_head, &rec) == -1) {
 703                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
 704                         return -1;
 705                 }
 706         }
 707
 708         /* the tdb_free() call might have increased the recovery size */
 709         *recovery_size = tdb_recovery_size(tdb);
 710
 711         /* round up to a multiple of page size */
 712         *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
 713         *recovery_offset = tdb->map_size;
 714         recovery_head = *recovery_offset;
 715
 716         if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
 717                                      (tdb->map_size - tdb->transaction->old_map_size) +
 718                                      sizeof(rec) + *recovery_max_size) == -1) {
 719                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
 720                 return -1;
 721         }
 722
 723         /* remap the file (if using mmap) */
 724         methods->tdb_oob(tdb, tdb->map_size + 1, 1);
 725
 726         /* we have to reset the old map size so that we don't try to expand the file
 727            again in the transaction commit, which would destroy the recovery area */
 728         tdb->transaction->old_map_size = tdb->map_size;
 729
 730         /* write the recovery header offset and sync - we can sync without a race here
 731            as the magic ptr in the recovery record has not been set */
 732         CONVERT(recovery_head);
 733         if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
 734                                &recovery_head, sizeof(tdb_off_t)) == -1) {
 735                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
 736                 return -1;
 737         }
 738         if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
 739                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
 740                 return -1;
 741         }
 742
 743         return 0;
 744 }
 745
 746
 747 /*
 748   setup the recovery data that will be used on a crash during commit
 749 */
 750 static int transaction_setup_recovery(struct tdb_context *tdb,
 751                                       tdb_off_t *magic_offset)
 752 {
 753         tdb_len_t recovery_size;
 754         unsigned char *data, *p;
 755         const struct tdb_methods *methods = tdb->transaction->io_methods;
 756         struct list_struct *rec;
 757         tdb_off_t recovery_offset, recovery_max_size;
 758         tdb_off_t old_map_size = tdb->transaction->old_map_size;
 759         uint32_t magic, tailer;
 760         int i;
 761
 762         /*
 763           check that the recovery area has enough space
 764         */
 765         if (tdb_recovery_allocate(tdb, &recovery_size,
 766                                   &recovery_offset, &recovery_max_size) == -1) {
 767                 return -1;
 768         }
 769
 770         data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
 771         if (data == NULL) {
 772                 tdb->ecode = TDB_ERR_OOM;
 773                 return -1;
 774         }
 775
 776         rec = (struct list_struct *)data;
 777         memset(rec, 0, sizeof(*rec));
 778
 779         rec->magic    = 0;
 780         rec->data_len = recovery_size;
 781         rec->rec_len  = recovery_max_size;
 782         rec->key_len  = old_map_size;
 783         CONVERT(rec);
 784
 785         /* build the recovery data into a single blob to allow us to do a single
 786            large write, which should be more efficient */
 787         p = data + sizeof(*rec);
 788         for (i=0;i<tdb->transaction->num_blocks;i++) {
 789                 tdb_off_t offset;
 790                 tdb_len_t length;
 791
 792                 if (tdb->transaction->blocks[i] == NULL) {
 793                         continue;
 794                 }
 795
 796                 offset = i * tdb->transaction->block_size;
 797                 length = tdb->transaction->block_size;
 798                 if (i == tdb->transaction->num_blocks-1) {
 799                         length = tdb->transaction->last_block_size;
 800                 }
 801
 802                 if (offset >= old_map_size) {
 803                         continue;
 804                 }
 805                 if (offset + length > tdb->transaction->old_map_size) {
 806                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
 807                         free(data);
 808                         tdb->ecode = TDB_ERR_CORRUPT;
 809                         return -1;
 810                 }
 811                 memcpy(p, &offset, 4);
 812                 memcpy(p+4, &length, 4);
 813                 if (DOCONV()) {
 814                         tdb_convert(p, 8);
 815                 }
 816                 /* the recovery area contains the old data, not the
 817                    new data, so we have to call the original tdb_read
 818                    method to get it */
 819                 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
 820                         free(data);
 821                         tdb->ecode = TDB_ERR_IO;
 822                         return -1;
 823                 }
 824                 p += 8 + length;
 825         }
 826
 827         /* and the tailer */
 828         tailer = sizeof(*rec) + recovery_max_size;
 829         memcpy(p, &tailer, 4);
 830         CONVERT(p);
 831
 832         /* write the recovery data to the recovery area */
 833         if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
 834                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
 835                 free(data);
 836                 tdb->ecode = TDB_ERR_IO;
 837                 return -1;
 838         }
 839         if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
 840                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
 841                 free(data);
 842                 tdb->ecode = TDB_ERR_IO;
 843                 return -1;
 844         }
 845
 846         /* as we don't have ordered writes, we have to sync the recovery
 847            data before we update the magic to indicate that the recovery
 848            data is present */
 849         if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
 850                 free(data);
 851                 return -1;
 852         }
 853
 854         free(data);
 855
 856         magic = TDB_RECOVERY_MAGIC;
 857         CONVERT(magic);
 858
 859         *magic_offset = recovery_offset + offsetof(struct list_struct, magic);
 860
 861         if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
 862                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
 863                 tdb->ecode = TDB_ERR_IO;
 864                 return -1;
 865         }
 866         if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
 867                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
 868                 tdb->ecode = TDB_ERR_IO;
 869                 return -1;
 870         }
 871
 872         /* ensure the recovery magic marker is on disk */
 873         if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
 874                 return -1;
 875         }
 876
 877         return 0;
 878 }
 879
 880 static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
 881 {
 882         const struct tdb_methods *methods;
 883
 884         if (tdb->transaction == NULL) {
 885                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
 886                 return -1;
 887         }
 888
 889         if (tdb->transaction->prepared) {
 890                 tdb->ecode = TDB_ERR_EINVAL;
 891                 _tdb_transaction_cancel(tdb);
 892                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
 893                 return -1;
 894         }
 895
 896         if (tdb->transaction->transaction_error) {
 897                 tdb->ecode = TDB_ERR_IO;
 898                 _tdb_transaction_cancel(tdb);
 899                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
 900                 return -1;
 901         }
 902
 903
 904         if (tdb->transaction->nesting != 0) {
 905                 return 0;
 906         }
 907
 908         /* check for a null transaction */
 909         if (tdb->transaction->blocks == NULL) {
 910                 return 0;
 911         }
 912
 913         methods = tdb->transaction->io_methods;
 914
 915         /* if there are any locks pending then the caller has not
 916            nested their locks properly, so fail the transaction */
 917         if (tdb->num_locks || tdb->global_lock.count) {
 918                 tdb->ecode = TDB_ERR_LOCK;
 919                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
 920                 _tdb_transaction_cancel(tdb);
 921                 return -1;
 922         }
 923
 924         /* upgrade the main transaction lock region to a write lock */
 925         if (tdb_brlock_upgrade(tdb, FREELIST_TOP, 0) == -1) {
 926                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
 927                 tdb->ecode = TDB_ERR_LOCK;
 928                 _tdb_transaction_cancel(tdb);
 929                 return -1;
 930         }
 931
 932         /* get the global lock - this prevents new users attaching to the database
 933            during the commit */
 934         if (tdb_brlock(tdb, GLOBAL_LOCK, F_WRLCK, F_SETLKW, 0, 1) == -1) {
 935                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get global lock\n"));
 936                 tdb->ecode = TDB_ERR_LOCK;
 937                 _tdb_transaction_cancel(tdb);
 938                 return -1;
 939         }
 940
 941         if (!(tdb->flags & TDB_NOSYNC)) {
 942                 /* write the recovery data to the end of the file */
 943                 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
 944                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
 945                         tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
 946                         _tdb_transaction_cancel(tdb);
 947                         return -1;
 948                 }
 949         }
 950
 951         tdb->transaction->prepared = true;
 952
 953         /* expand the file to the new size if needed */
 954         if (tdb->map_size != tdb->transaction->old_map_size) {
 955                 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
 956                                              tdb->map_size -
 957                                              tdb->transaction->old_map_size) == -1) {
 958                         tdb->ecode = TDB_ERR_IO;
 959                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
 960                         tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
 961                         _tdb_transaction_cancel(tdb);
 962                         return -1;
 963                 }
 964                 tdb->map_size = tdb->transaction->old_map_size;
 965                 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
 966         }
 967
 968         /* Keep the global lock until the actual commit */
 969
 970         return 0;
 971 }
 972
 973 /*
 974    prepare to commit the current transaction
 975 */
 976 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
 977 {
 978         tdb_trace(tdb, "tdb_transaction_prepare_commit");
 979         return _tdb_transaction_prepare_commit(tdb);
 980 }
 981
 982 /*
 983   commit the current transaction
 984 */
 985 int tdb_transaction_commit(struct tdb_context *tdb)
 986 {
 987         const struct tdb_methods *methods;
 988         int i;
 989         bool need_repack;
 990
 991         if (tdb->transaction == NULL) {
 992                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
 993                 return -1;
 994         }
 995
 996         tdb_trace(tdb, "tdb_transaction_commit");
 997
 998         if (tdb->transaction->transaction_error) {
 999                 tdb->ecode = TDB_ERR_IO;
1000                 _tdb_transaction_cancel(tdb);
1001                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
1002                 return -1;
1003         }
1004
1005
1006         if (tdb->transaction->nesting != 0) {
1007                 tdb->transaction->nesting--;
1008                 return 0;
1009         }
1010
1011         /* check for a null transaction */
1012         if (tdb->transaction->blocks == NULL) {
1013                 _tdb_transaction_cancel(tdb);
1014                 return 0;
1015         }
1016
1017         if (!tdb->transaction->prepared) {
1018                 int ret = _tdb_transaction_prepare_commit(tdb);
1019                 if (ret)
1020                         return ret;
1021         }
1022
1023         methods = tdb->transaction->io_methods;
1024
1025         /* perform all the writes */
1026         for (i=0;i<tdb->transaction->num_blocks;i++) {
1027                 tdb_off_t offset;
1028                 tdb_len_t length;
1029
1030                 if (tdb->transaction->blocks[i] == NULL) {
1031                         continue;
1032                 }
1033
1034                 offset = i * tdb->transaction->block_size;
1035                 length = tdb->transaction->block_size;
1036                 if (i == tdb->transaction->num_blocks-1) {
1037                         length = tdb->transaction->last_block_size;
1038                 }
1039
1040                 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1041                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
1042
1043                         /* we've overwritten part of the data and
1044                            possibly expanded the file, so we need to
1045                            run the crash recovery code */
1046                         tdb->methods = methods;
1047                         tdb_transaction_recover(tdb);
1048
1049                         _tdb_transaction_cancel(tdb);
1050                         tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
1051
1052                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
1053                         return -1;
1054                 }
1055                 SAFE_FREE(tdb->transaction->blocks[i]);
1056         }
1057
1058         SAFE_FREE(tdb->transaction->blocks);
1059         tdb->transaction->num_blocks = 0;
1060
1061         /* ensure the new data is on disk */
1062         if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1063                 return -1;
1064         }
1065
1066         tdb_brlock(tdb, GLOBAL_LOCK, F_UNLCK, F_SETLKW, 0, 1);
1067
1068         /*
1069           TODO: maybe write to some dummy hdr field, or write to magic
1070           offset without mmap, before the last sync, instead of the
1071           utime() call
1072         */
1073
1074         /* on some systems (like Linux 2.6.x) changes via mmap/msync
1075            don't change the mtime of the file, this means the file may
1076            not be backed up (as tdb rounding to block sizes means that
1077            file size changes are quite rare too). The following forces
1078            mtime changes when a transaction completes */
1079 #ifdef HAVE_UTIME
1080         utime(tdb->name, NULL);
1081 #endif
1082
1083         need_repack = tdb->transaction->need_repack;
1084
1085         /* use a transaction cancel to free memory and remove the
1086            transaction locks */
1087         _tdb_transaction_cancel(tdb);
1088
1089         if (need_repack) {
1090                 return tdb_repack(tdb);
1091         }
1092
1093         return 0;
1094 }
1095
1096
1097 /*
1098   recover from an aborted transaction. Must be called with exclusive
1099   database write access already established (including the global
1100   lock to prevent new processes attaching)
1101 */
1102 int tdb_transaction_recover(struct tdb_context *tdb)
1103 {
1104         tdb_off_t recovery_head, recovery_eof;
1105         unsigned char *data, *p;
1106         uint32_t zero = 0;
1107         struct list_struct rec;
1108
1109         /* find the recovery area */
1110         if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1111                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1112                 tdb->ecode = TDB_ERR_IO;
1113                 return -1;
1114         }
1115
1116         if (recovery_head == 0) {
1117                 /* we have never allocated a recovery record */
1118                 return 0;
1119         }
1120
1121         /* read the recovery record */
1122         if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1123                                    sizeof(rec), DOCONV()) == -1) {
1124                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1125                 tdb->ecode = TDB_ERR_IO;
1126                 return -1;
1127         }
1128
1129         if (rec.magic != TDB_RECOVERY_MAGIC) {
1130                 /* there is no valid recovery data */
1131                 return 0;
1132         }
1133
1134         if (tdb->read_only) {
1135                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1136                 tdb->ecode = TDB_ERR_CORRUPT;
1137                 return -1;
1138         }
1139
1140         recovery_eof = rec.key_len;
1141
1142         data = (unsigned char *)malloc(rec.data_len);
1143         if (data == NULL) {
1144                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1145                 tdb->ecode = TDB_ERR_OOM;
1146                 return -1;
1147         }
1148
1149         /* read the full recovery data */
1150         if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1151                                    rec.data_len, 0) == -1) {
1152                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1153                 tdb->ecode = TDB_ERR_IO;
1154                 return -1;
1155         }
1156
1157         /* recover the file data */
1158         p = data;
1159         while (p+8 < data + rec.data_len) {
1160                 uint32_t ofs, len;
1161                 if (DOCONV()) {
1162                         tdb_convert(p, 8);
1163                 }
1164                 memcpy(&ofs, p, 4);
1165                 memcpy(&len, p+4, 4);
1166
1167                 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1168                         free(data);
1169                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1170                         tdb->ecode = TDB_ERR_IO;
1171                         return -1;
1172                 }
1173                 p += 8 + len;
1174         }
1175
1176         free(data);
1177
1178         if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1179                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1180                 tdb->ecode = TDB_ERR_IO;
1181                 return -1;
1182         }
1183
1184         /* if the recovery area is after the recovered eof then remove it */
1185         if (recovery_eof <= recovery_head) {
1186                 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1187                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1188                         tdb->ecode = TDB_ERR_IO;
1189                         return -1;
1190                 }
1191         }
1192
1193         /* remove the recovery magic */
1194         if (tdb_ofs_write(tdb, recovery_head + offsetof(struct list_struct, magic),
1195                           &zero) == -1) {
1196                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1197                 tdb->ecode = TDB_ERR_IO;
1198                 return -1;
1199         }
1200
1201         /* reduce the file size to the old size */
1202         tdb_munmap(tdb);
1203         if (ftruncate(tdb->fd, recovery_eof) != 0) {
1204                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
1205                 tdb->ecode = TDB_ERR_IO;
1206                 return -1;
1207         }
1208         tdb->map_size = recovery_eof;
1209         tdb_mmap(tdb);
1210
1211         if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1212                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1213                 tdb->ecode = TDB_ERR_IO;
1214                 return -1;
1215         }
1216
1217         TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",
1218                  recovery_eof));
1219
1220         /* all done */
1221         return 0;
1222 }