git.ozlabs.org Git - ccan/blob - ccan/tdb/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     open 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 nesting is enabled.
  90     It resets the TDB_DISALLOW_NESTING flag, as both cannot be used together.
  91     The default is that transaction nesting is allowed.
  92     Note: this default may change in future versions of tdb.
  93
  94     Beware. when transactions are nested a transaction successfully
  95     completed with tdb_transaction_commit() can be silently unrolled later.
  96
  97   - if TDB_DISALLOW_NESTING is passed to flags in tdb open, or added using
  98     tdb_add_flags() transaction nesting is disabled.
  99     It resets the TDB_ALLOW_NESTING flag, as both cannot be used together.
 100     An attempt create a nested transaction will fail with TDB_ERR_NESTING.
 101     The default is that transaction nesting is allowed.
 102     Note: this default may change in future versions of tdb.
 103 */
 104
 105
 106 /*
 107   hold the context of any current transaction
 108 */
 109 struct tdb_transaction {
 110         /* we keep a mirrored copy of the tdb hash heads here so
 111            tdb_next_hash_chain() can operate efficiently */
 112         uint32_t *hash_heads;
 113
 114         /* the original io methods - used to do IOs to the real db */
 115         const struct tdb_methods *io_methods;
 116
 117         /* the list of transaction blocks. When a block is first
 118            written to, it gets created in this list */
 119         uint8_t **blocks;
 120         uint32_t num_blocks;
 121         uint32_t block_size;      /* bytes in each block */
 122         uint32_t last_block_size; /* number of valid bytes in the last block */
 123
 124         /* non-zero when an internal transaction error has
 125            occurred. All write operations will then fail until the
 126            transaction is ended */
 127         int transaction_error;
 128
 129         /* when inside a transaction we need to keep track of any
 130            nested tdb_transaction_start() calls, as these are allowed,
 131            but don't create a new transaction */
 132         int nesting;
 133
 134         /* set when a prepare has already occurred */
 135         bool prepared;
 136         tdb_off_t magic_offset;
 137
 138         /* old file size before transaction */
 139         tdb_len_t old_map_size;
 140
 141         /* we should re-pack on commit */
 142         bool need_repack;
 143 };
 144
 145
 146 /*
 147   read while in a transaction. We need to check first if the data is in our list
 148   of transaction elements, then if not do a real read
 149 */
 150 static int transaction_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
 151                             tdb_len_t len, int cv)
 152 {
 153         uint32_t blk;
 154
 155         /* break it down into block sized ops */
 156         while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
 157                 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
 158                 if (transaction_read(tdb, off, buf, len2, cv) != 0) {
 159                         return -1;
 160                 }
 161                 len -= len2;
 162                 off += len2;
 163                 buf = (void *)(len2 + (char *)buf);
 164         }
 165
 166         if (len == 0) {
 167                 return 0;
 168         }
 169
 170         blk = off / tdb->transaction->block_size;
 171
 172         /* see if we have it in the block list */
 173         if (tdb->transaction->num_blocks <= blk ||
 174             tdb->transaction->blocks[blk] == NULL) {
 175                 /* nope, do a real read */
 176                 if (tdb->transaction->io_methods->tdb_read(tdb, off, buf, len, cv) != 0) {
 177                         goto fail;
 178                 }
 179                 return 0;
 180         }
 181
 182         /* it is in the block list. Now check for the last block */
 183         if (blk == tdb->transaction->num_blocks-1) {
 184                 if (len > tdb->transaction->last_block_size) {
 185                         goto fail;
 186                 }
 187         }
 188
 189         /* now copy it out of this block */
 190         memcpy(buf, tdb->transaction->blocks[blk] + (off % tdb->transaction->block_size), len);
 191         if (cv) {
 192                 tdb_convert(buf, len);
 193         }
 194         return 0;
 195
 196 fail:
 197         TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_read: failed at off=%d len=%d\n", off, len));
 198         tdb->ecode = TDB_ERR_IO;
 199         tdb->transaction->transaction_error = 1;
 200         return -1;
 201 }
 202
 203
 204 /*
 205   write while in a transaction
 206 */
 207 static int transaction_write(struct tdb_context *tdb, tdb_off_t off,
 208                              const void *buf, tdb_len_t len)
 209 {
 210         uint32_t blk;
 211
 212         /* Only a commit is allowed on a prepared transaction */
 213         if (tdb->transaction->prepared) {
 214                 tdb->ecode = TDB_ERR_EINVAL;
 215                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: transaction already prepared, write not allowed\n"));
 216                 tdb->transaction->transaction_error = 1;
 217                 return -1;
 218         }
 219
 220         /* if the write is to a hash head, then update the transaction
 221            hash heads */
 222         if (len == sizeof(tdb_off_t) && off >= FREELIST_TOP &&
 223             off < FREELIST_TOP+TDB_HASHTABLE_SIZE(tdb)) {
 224                 uint32_t chain = (off-FREELIST_TOP) / sizeof(tdb_off_t);
 225                 memcpy(&tdb->transaction->hash_heads[chain], buf, len);
 226         }
 227
 228         /* break it up into block sized chunks */
 229         while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
 230                 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
 231                 if (transaction_write(tdb, off, buf, len2) != 0) {
 232                         return -1;
 233                 }
 234                 len -= len2;
 235                 off += len2;
 236                 if (buf != NULL) {
 237                         buf = (const void *)(len2 + (const char *)buf);
 238                 }
 239         }
 240
 241         if (len == 0) {
 242                 return 0;
 243         }
 244
 245         blk = off / tdb->transaction->block_size;
 246         off = off % tdb->transaction->block_size;
 247
 248         if (tdb->transaction->num_blocks <= blk) {
 249                 uint8_t **new_blocks;
 250                 /* expand the blocks array */
 251                 if (tdb->transaction->blocks == NULL) {
 252                         new_blocks = (uint8_t **)malloc(
 253                                 (blk+1)*sizeof(uint8_t *));
 254                 } else {
 255                         new_blocks = (uint8_t **)realloc(
 256                                 tdb->transaction->blocks,
 257                                 (blk+1)*sizeof(uint8_t *));
 258                 }
 259                 if (new_blocks == NULL) {
 260                         tdb->ecode = TDB_ERR_OOM;
 261                         goto fail;
 262                 }
 263                 memset(&new_blocks[tdb->transaction->num_blocks], 0,
 264                        (1+(blk - tdb->transaction->num_blocks))*sizeof(uint8_t *));
 265                 tdb->transaction->blocks = new_blocks;
 266                 tdb->transaction->num_blocks = blk+1;
 267                 tdb->transaction->last_block_size = 0;
 268         }
 269
 270         /* allocate and fill a block? */
 271         if (tdb->transaction->blocks[blk] == NULL) {
 272                 tdb->transaction->blocks[blk] = (uint8_t *)calloc(tdb->transaction->block_size, 1);
 273                 if (tdb->transaction->blocks[blk] == NULL) {
 274                         tdb->ecode = TDB_ERR_OOM;
 275                         tdb->transaction->transaction_error = 1;
 276                         return -1;
 277                 }
 278                 if (tdb->transaction->old_map_size > blk * tdb->transaction->block_size) {
 279                         tdb_len_t len2 = tdb->transaction->block_size;
 280                         if (len2 + (blk * tdb->transaction->block_size) > tdb->transaction->old_map_size) {
 281                                 len2 = tdb->transaction->old_map_size - (blk * tdb->transaction->block_size);
 282                         }
 283                         if (tdb->transaction->io_methods->tdb_read(tdb, blk * tdb->transaction->block_size,
 284                                                                    tdb->transaction->blocks[blk],
 285                                                                    len2, 0) != 0) {
 286                                 SAFE_FREE(tdb->transaction->blocks[blk]);
 287                                 tdb->ecode = TDB_ERR_IO;
 288                                 goto fail;
 289                         }
 290                         if (blk == tdb->transaction->num_blocks-1) {
 291                                 tdb->transaction->last_block_size = len2;
 292                         }
 293                 }
 294         }
 295
 296         /* overwrite part of an existing block */
 297         if (buf == NULL) {
 298                 memset(tdb->transaction->blocks[blk] + off, 0, len);
 299         } else {
 300                 memcpy(tdb->transaction->blocks[blk] + off, buf, len);
 301         }
 302         if (blk == tdb->transaction->num_blocks-1) {
 303                 if (len + off > tdb->transaction->last_block_size) {
 304                         tdb->transaction->last_block_size = len + off;
 305                 }
 306         }
 307
 308         return 0;
 309
 310 fail:
 311         TDB_LOG((tdb, TDB_DEBUG_FATAL, "transaction_write: failed at off=%d len=%d\n",
 312                  (blk*tdb->transaction->block_size) + off, len));
 313         tdb->transaction->transaction_error = 1;
 314         return -1;
 315 }
 316
 317
 318 /*
 319   write while in a transaction - this varient never expands the transaction blocks, it only
 320   updates existing blocks. This means it cannot change the recovery size
 321 */
 322 static int transaction_write_existing(struct tdb_context *tdb, tdb_off_t off,
 323                                       const void *buf, tdb_len_t len)
 324 {
 325         uint32_t blk;
 326
 327         /* break it up into block sized chunks */
 328         while (len + (off % tdb->transaction->block_size) > tdb->transaction->block_size) {
 329                 tdb_len_t len2 = tdb->transaction->block_size - (off % tdb->transaction->block_size);
 330                 if (transaction_write_existing(tdb, off, buf, len2) != 0) {
 331                         return -1;
 332                 }
 333                 len -= len2;
 334                 off += len2;
 335                 if (buf != NULL) {
 336                         buf = (const void *)(len2 + (const char *)buf);
 337                 }
 338         }
 339
 340         if (len == 0) {
 341                 return 0;
 342         }
 343
 344         blk = off / tdb->transaction->block_size;
 345         off = off % tdb->transaction->block_size;
 346
 347         if (tdb->transaction->num_blocks <= blk ||
 348             tdb->transaction->blocks[blk] == NULL) {
 349                 return 0;
 350         }
 351
 352         if (blk == tdb->transaction->num_blocks-1 &&
 353             off + len > tdb->transaction->last_block_size) {
 354                 if (off >= tdb->transaction->last_block_size) {
 355                         return 0;
 356                 }
 357                 len = tdb->transaction->last_block_size - off;
 358         }
 359
 360         /* overwrite part of an existing block */
 361         memcpy(tdb->transaction->blocks[blk] + off, buf, len);
 362
 363         return 0;
 364 }
 365
 366
 367 /*
 368   accelerated hash chain head search, using the cached hash heads
 369 */
 370 static void transaction_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
 371 {
 372         uint32_t h = *chain;
 373         for (;h < tdb->header.hash_size;h++) {
 374                 /* the +1 takes account of the freelist */
 375                 if (0 != tdb->transaction->hash_heads[h+1]) {
 376                         break;
 377                 }
 378         }
 379         (*chain) = h;
 380 }
 381
 382 /*
 383   out of bounds check during a transaction
 384 */
 385 static int transaction_oob(struct tdb_context *tdb, tdb_off_t len, int probe)
 386 {
 387         if (len <= tdb->map_size) {
 388                 return 0;
 389         }
 390         tdb->ecode = TDB_ERR_IO;
 391         return -1;
 392 }
 393
 394 /*
 395   transaction version of tdb_expand().
 396 */
 397 static int transaction_expand_file(struct tdb_context *tdb, tdb_off_t size,
 398                                    tdb_off_t addition)
 399 {
 400         /* add a write to the transaction elements, so subsequent
 401            reads see the zero data */
 402         if (transaction_write(tdb, size, NULL, addition) != 0) {
 403                 return -1;
 404         }
 405
 406         tdb->transaction->need_repack = true;
 407
 408         return 0;
 409 }
 410
 411 /*
 412   brlock during a transaction - ignore them
 413 */
 414 static int transaction_brlock(struct tdb_context *tdb,
 415                               int rw_type, tdb_off_t offset, size_t len,
 416                               enum tdb_lock_flags flags)
 417 {
 418         /* FIXME: We actually grab the open lock during a transaction. */
 419         if (offset == OPEN_LOCK)
 420                 return tdb_brlock(tdb, rw_type, offset, len, flags);
 421         return 0;
 422 }
 423
 424 static int transaction_brunlock(struct tdb_context *tdb,
 425                                 int rw_type, tdb_off_t offset, size_t len)
 426 {
 427         return 0;
 428 }
 429
 430 static const struct tdb_methods transaction_methods = {
 431         transaction_read,
 432         transaction_write,
 433         transaction_next_hash_chain,
 434         transaction_oob,
 435         transaction_expand_file,
 436         transaction_brlock,
 437         transaction_brunlock
 438 };
 439
 440 /*
 441   sync to disk
 442 */
 443 static int transaction_sync(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t length)
 444 {
 445         if (tdb->flags & TDB_NOSYNC) {
 446                 return 0;
 447         }
 448
 449         if (fsync(tdb->fd) != 0) {
 450                 tdb->ecode = TDB_ERR_IO;
 451                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: fsync failed\n"));
 452                 return -1;
 453         }
 454 #ifdef MS_SYNC
 455         if (tdb->map_ptr) {
 456                 tdb_off_t moffset = offset & ~(tdb->page_size-1);
 457                 if (msync(moffset + (char *)tdb->map_ptr,
 458                           length + (offset - moffset), MS_SYNC) != 0) {
 459                         tdb->ecode = TDB_ERR_IO;
 460                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction: msync failed - %s\n",
 461                                  strerror(errno)));
 462                         return -1;
 463                 }
 464         }
 465 #endif
 466         return 0;
 467 }
 468
 469
 470 static int _tdb_transaction_cancel(struct tdb_context *tdb)
 471 {
 472         int i, ret = 0;
 473
 474         if (tdb->transaction == NULL) {
 475                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_cancel: no transaction\n"));
 476                 return -1;
 477         }
 478
 479         if (tdb->transaction->nesting != 0) {
 480                 tdb->transaction->transaction_error = 1;
 481                 tdb->transaction->nesting--;
 482                 return 0;
 483         }
 484
 485         tdb->map_size = tdb->transaction->old_map_size;
 486
 487         /* free all the transaction blocks */
 488         for (i=0;i<tdb->transaction->num_blocks;i++) {
 489                 if (tdb->transaction->blocks[i] != NULL) {
 490                         free(tdb->transaction->blocks[i]);
 491                 }
 492         }
 493         SAFE_FREE(tdb->transaction->blocks);
 494
 495         if (tdb->transaction->magic_offset) {
 496                 const struct tdb_methods *methods = tdb->transaction->io_methods;
 497                 uint32_t invalid = TDB_RECOVERY_INVALID_MAGIC;
 498
 499                 /* remove the recovery marker */
 500                 if (methods->tdb_write(tdb, tdb->transaction->magic_offset, &invalid, 4) == -1 ||
 501                 transaction_sync(tdb, tdb->transaction->magic_offset, 4) == -1) {
 502                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_cancel: failed to remove recovery magic\n"));
 503                         ret = -1;
 504                 }
 505         }
 506
 507         /* This also removes the OPEN_LOCK, if we have it. */
 508         tdb_release_extra_locks(tdb);
 509
 510         /* restore the normal io methods */
 511         tdb->methods = tdb->transaction->io_methods;
 512
 513         tdb_transaction_unlock(tdb, F_WRLCK);
 514         SAFE_FREE(tdb->transaction->hash_heads);
 515         SAFE_FREE(tdb->transaction);
 516
 517         return ret;
 518 }
 519
 520 /*
 521   start a tdb transaction. No token is returned, as only a single
 522   transaction is allowed to be pending per tdb_context
 523 */
 524 int tdb_transaction_start(struct tdb_context *tdb)
 525 {
 526         /* some sanity checks */
 527         if (tdb->read_only || (tdb->flags & TDB_INTERNAL) || tdb->traverse_read) {
 528                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction on a read-only or internal db\n"));
 529                 tdb->ecode = TDB_ERR_EINVAL;
 530                 return -1;
 531         }
 532
 533         /* cope with nested tdb_transaction_start() calls */
 534         if (tdb->transaction != NULL) {
 535                 if (!(tdb->flags & TDB_ALLOW_NESTING)) {
 536                         tdb->ecode = TDB_ERR_NESTING;
 537                         return -1;
 538                 }
 539                 tdb_trace(tdb, "tdb_transaction_start");
 540                 tdb->transaction->nesting++;
 541                 TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_start: nesting %d\n",
 542                          tdb->transaction->nesting));
 543                 return 0;
 544         }
 545
 546         if (tdb_have_extra_locks(tdb)) {
 547                 /* the caller must not have any locks when starting a
 548                    transaction as otherwise we'll be screwed by lack
 549                    of nested locks in posix */
 550                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction with locks held\n"));
 551                 tdb->ecode = TDB_ERR_LOCK;
 552                 return -1;
 553         }
 554
 555         if (tdb->travlocks.next != NULL) {
 556                 /* you cannot use transactions inside a traverse (although you can use
 557                    traverse inside a transaction) as otherwise you can end up with
 558                    deadlock */
 559                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: cannot start a transaction within a traverse\n"));
 560                 tdb->ecode = TDB_ERR_LOCK;
 561                 return -1;
 562         }
 563
 564         tdb->transaction = (struct tdb_transaction *)
 565                 calloc(sizeof(struct tdb_transaction), 1);
 566         if (tdb->transaction == NULL) {
 567                 tdb->ecode = TDB_ERR_OOM;
 568                 return -1;
 569         }
 570
 571         /* a page at a time seems like a reasonable compromise between compactness and efficiency */
 572         tdb->transaction->block_size = tdb->page_size;
 573
 574         /* get the transaction write lock. This is a blocking lock. As
 575            discussed with Volker, there are a number of ways we could
 576            make this async, which we will probably do in the future */
 577         if (tdb_transaction_lock(tdb, F_WRLCK) == -1) {
 578                 SAFE_FREE(tdb->transaction->blocks);
 579                 SAFE_FREE(tdb->transaction);
 580                 return -1;
 581         }
 582
 583         /* get a read lock from the freelist to the end of file. This
 584            is upgraded to a write lock during the commit */
 585         if (tdb_allrecord_lock(tdb, F_RDLCK, TDB_LOCK_WAIT, true) == -1) {
 586                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_start: failed to get hash locks\n"));
 587                 goto fail_allrecord_lock;
 588         }
 589
 590         /* setup a copy of the hash table heads so the hash scan in
 591            traverse can be fast */
 592         tdb->transaction->hash_heads = (uint32_t *)
 593                 calloc(tdb->header.hash_size+1, sizeof(uint32_t));
 594         if (tdb->transaction->hash_heads == NULL) {
 595                 tdb->ecode = TDB_ERR_OOM;
 596                 goto fail;
 597         }
 598         if (tdb->methods->tdb_read(tdb, FREELIST_TOP, tdb->transaction->hash_heads,
 599                                    TDB_HASHTABLE_SIZE(tdb), 0) != 0) {
 600                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_start: failed to read hash heads\n"));
 601                 tdb->ecode = TDB_ERR_IO;
 602                 goto fail;
 603         }
 604
 605         /* make sure we know about any file expansions already done by
 606            anyone else */
 607         tdb->methods->tdb_oob(tdb, tdb->map_size + 1, 1);
 608         tdb->transaction->old_map_size = tdb->map_size;
 609
 610         /* finally hook the io methods, replacing them with
 611            transaction specific methods */
 612         tdb->transaction->io_methods = tdb->methods;
 613         tdb->methods = &transaction_methods;
 614
 615         /* Trace at the end, so we get sequence number correct. */
 616         tdb_trace(tdb, "tdb_transaction_start");
 617         return 0;
 618
 619 fail:
 620         tdb_allrecord_unlock(tdb, F_RDLCK, false);
 621 fail_allrecord_lock:
 622         tdb_transaction_unlock(tdb, F_WRLCK);
 623         SAFE_FREE(tdb->transaction->blocks);
 624         SAFE_FREE(tdb->transaction->hash_heads);
 625         SAFE_FREE(tdb->transaction);
 626         return -1;
 627 }
 628
 629
 630 /*
 631   cancel the current transaction
 632 */
 633 int tdb_transaction_cancel(struct tdb_context *tdb)
 634 {
 635         tdb_trace(tdb, "tdb_transaction_cancel");
 636         return _tdb_transaction_cancel(tdb);
 637 }
 638
 639 /*
 640   work out how much space the linearised recovery data will consume
 641 */
 642 static tdb_len_t tdb_recovery_size(struct tdb_context *tdb)
 643 {
 644         tdb_len_t recovery_size = 0;
 645         int i;
 646
 647         recovery_size = sizeof(uint32_t);
 648         for (i=0;i<tdb->transaction->num_blocks;i++) {
 649                 if (i * tdb->transaction->block_size >= tdb->transaction->old_map_size) {
 650                         break;
 651                 }
 652                 if (tdb->transaction->blocks[i] == NULL) {
 653                         continue;
 654                 }
 655                 recovery_size += 2*sizeof(tdb_off_t);
 656                 if (i == tdb->transaction->num_blocks-1) {
 657                         recovery_size += tdb->transaction->last_block_size;
 658                 } else {
 659                         recovery_size += tdb->transaction->block_size;
 660                 }
 661         }
 662
 663         return recovery_size;
 664 }
 665
 666 /*
 667   allocate the recovery area, or use an existing recovery area if it is
 668   large enough
 669 */
 670 static int tdb_recovery_allocate(struct tdb_context *tdb,
 671                                  tdb_len_t *recovery_size,
 672                                  tdb_off_t *recovery_offset,
 673                                  tdb_len_t *recovery_max_size)
 674 {
 675         struct tdb_record rec;
 676         const struct tdb_methods *methods = tdb->transaction->io_methods;
 677         tdb_off_t recovery_head;
 678
 679         if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
 680                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery head\n"));
 681                 return -1;
 682         }
 683
 684         rec.rec_len = 0;
 685
 686         if (recovery_head != 0) {
 687                 if (methods->tdb_read(tdb, recovery_head, &rec, sizeof(rec), DOCONV()) == -1) {
 688                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to read recovery record\n"));
 689                         return -1;
 690                 }
 691                 /* ignore invalid recovery regions: can happen in crash */
 692                 if (rec.magic != TDB_RECOVERY_MAGIC &&
 693                     rec.magic != TDB_RECOVERY_INVALID_MAGIC) {
 694                         recovery_head = 0;
 695                 }
 696         }
 697
 698         *recovery_size = tdb_recovery_size(tdb);
 699
 700         if (recovery_head != 0 && *recovery_size <= rec.rec_len) {
 701                 /* it fits in the existing area */
 702                 *recovery_max_size = rec.rec_len;
 703                 *recovery_offset = recovery_head;
 704                 return 0;
 705         }
 706
 707         /* we need to free up the old recovery area, then allocate a
 708            new one at the end of the file. Note that we cannot use
 709            tdb_allocate() to allocate the new one as that might return
 710            us an area that is being currently used (as of the start of
 711            the transaction) */
 712         if (recovery_head != 0) {
 713                 if (tdb_free(tdb, recovery_head, &rec) == -1) {
 714                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to free previous recovery area\n"));
 715                         return -1;
 716                 }
 717         }
 718
 719         /* the tdb_free() call might have increased the recovery size */
 720         *recovery_size = tdb_recovery_size(tdb);
 721
 722         /* round up to a multiple of page size */
 723         *recovery_max_size = TDB_ALIGN(sizeof(rec) + *recovery_size, tdb->page_size) - sizeof(rec);
 724         *recovery_offset = tdb->map_size;
 725         recovery_head = *recovery_offset;
 726
 727         if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
 728                                      (tdb->map_size - tdb->transaction->old_map_size) +
 729                                      sizeof(rec) + *recovery_max_size) == -1) {
 730                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to create recovery area\n"));
 731                 return -1;
 732         }
 733
 734         /* remap the file (if using mmap) */
 735         methods->tdb_oob(tdb, tdb->map_size + 1, 1);
 736
 737         /* we have to reset the old map size so that we don't try to expand the file
 738            again in the transaction commit, which would destroy the recovery area */
 739         tdb->transaction->old_map_size = tdb->map_size;
 740
 741         /* write the recovery header offset and sync - we can sync without a race here
 742            as the magic ptr in the recovery record has not been set */
 743         CONVERT(recovery_head);
 744         if (methods->tdb_write(tdb, TDB_RECOVERY_HEAD,
 745                                &recovery_head, sizeof(tdb_off_t)) == -1) {
 746                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
 747                 return -1;
 748         }
 749         if (transaction_write_existing(tdb, TDB_RECOVERY_HEAD, &recovery_head, sizeof(tdb_off_t)) == -1) {
 750                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_recovery_allocate: failed to write recovery head\n"));
 751                 return -1;
 752         }
 753
 754         return 0;
 755 }
 756
 757
 758 /*
 759   setup the recovery data that will be used on a crash during commit
 760 */
 761 static int transaction_setup_recovery(struct tdb_context *tdb,
 762                                       tdb_off_t *magic_offset)
 763 {
 764         tdb_len_t recovery_size;
 765         unsigned char *data, *p;
 766         const struct tdb_methods *methods = tdb->transaction->io_methods;
 767         struct tdb_record *rec;
 768         tdb_off_t recovery_offset, recovery_max_size;
 769         tdb_off_t old_map_size = tdb->transaction->old_map_size;
 770         uint32_t magic, tailer;
 771         int i;
 772
 773         /*
 774           check that the recovery area has enough space
 775         */
 776         if (tdb_recovery_allocate(tdb, &recovery_size,
 777                                   &recovery_offset, &recovery_max_size) == -1) {
 778                 return -1;
 779         }
 780
 781         data = (unsigned char *)malloc(recovery_size + sizeof(*rec));
 782         if (data == NULL) {
 783                 tdb->ecode = TDB_ERR_OOM;
 784                 return -1;
 785         }
 786
 787         rec = (struct tdb_record *)data;
 788         memset(rec, 0, sizeof(*rec));
 789
 790         rec->magic    = TDB_RECOVERY_INVALID_MAGIC;
 791         rec->data_len = recovery_size;
 792         rec->rec_len  = recovery_max_size;
 793         rec->key_len  = old_map_size;
 794         CONVERT(rec);
 795
 796         /* build the recovery data into a single blob to allow us to do a single
 797            large write, which should be more efficient */
 798         p = data + sizeof(*rec);
 799         for (i=0;i<tdb->transaction->num_blocks;i++) {
 800                 tdb_off_t offset;
 801                 tdb_len_t length;
 802
 803                 if (tdb->transaction->blocks[i] == NULL) {
 804                         continue;
 805                 }
 806
 807                 offset = i * tdb->transaction->block_size;
 808                 length = tdb->transaction->block_size;
 809                 if (i == tdb->transaction->num_blocks-1) {
 810                         length = tdb->transaction->last_block_size;
 811                 }
 812
 813                 if (offset >= old_map_size) {
 814                         continue;
 815                 }
 816                 if (offset + length > tdb->transaction->old_map_size) {
 817                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: transaction data over new region boundary\n"));
 818                         free(data);
 819                         tdb->ecode = TDB_ERR_CORRUPT;
 820                         return -1;
 821                 }
 822                 memcpy(p, &offset, 4);
 823                 memcpy(p+4, &length, 4);
 824                 if (DOCONV()) {
 825                         tdb_convert(p, 8);
 826                 }
 827                 /* the recovery area contains the old data, not the
 828                    new data, so we have to call the original tdb_read
 829                    method to get it */
 830                 if (methods->tdb_read(tdb, offset, p + 8, length, 0) != 0) {
 831                         free(data);
 832                         tdb->ecode = TDB_ERR_IO;
 833                         return -1;
 834                 }
 835                 p += 8 + length;
 836         }
 837
 838         /* and the tailer */
 839         tailer = sizeof(*rec) + recovery_max_size;
 840         memcpy(p, &tailer, 4);
 841         CONVERT(p);
 842
 843         /* write the recovery data to the recovery area */
 844         if (methods->tdb_write(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
 845                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery data\n"));
 846                 free(data);
 847                 tdb->ecode = TDB_ERR_IO;
 848                 return -1;
 849         }
 850         if (transaction_write_existing(tdb, recovery_offset, data, sizeof(*rec) + recovery_size) == -1) {
 851                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery data\n"));
 852                 free(data);
 853                 tdb->ecode = TDB_ERR_IO;
 854                 return -1;
 855         }
 856
 857         /* as we don't have ordered writes, we have to sync the recovery
 858            data before we update the magic to indicate that the recovery
 859            data is present */
 860         if (transaction_sync(tdb, recovery_offset, sizeof(*rec) + recovery_size) == -1) {
 861                 free(data);
 862                 return -1;
 863         }
 864
 865         free(data);
 866
 867         magic = TDB_RECOVERY_MAGIC;
 868         CONVERT(magic);
 869
 870         *magic_offset = recovery_offset + offsetof(struct tdb_record, magic);
 871
 872         if (methods->tdb_write(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
 873                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write recovery magic\n"));
 874                 tdb->ecode = TDB_ERR_IO;
 875                 return -1;
 876         }
 877         if (transaction_write_existing(tdb, *magic_offset, &magic, sizeof(magic)) == -1) {
 878                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_setup_recovery: failed to write secondary recovery magic\n"));
 879                 tdb->ecode = TDB_ERR_IO;
 880                 return -1;
 881         }
 882
 883         /* ensure the recovery magic marker is on disk */
 884         if (transaction_sync(tdb, *magic_offset, sizeof(magic)) == -1) {
 885                 return -1;
 886         }
 887
 888         return 0;
 889 }
 890
 891 static int _tdb_transaction_prepare_commit(struct tdb_context *tdb)
 892 {
 893         const struct tdb_methods *methods;
 894
 895         if (tdb->transaction == NULL) {
 896                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: no transaction\n"));
 897                 return -1;
 898         }
 899
 900         if (tdb->transaction->prepared) {
 901                 tdb->ecode = TDB_ERR_EINVAL;
 902                 _tdb_transaction_cancel(tdb);
 903                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction already prepared\n"));
 904                 return -1;
 905         }
 906
 907         if (tdb->transaction->transaction_error) {
 908                 tdb->ecode = TDB_ERR_IO;
 909                 _tdb_transaction_cancel(tdb);
 910                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: transaction error pending\n"));
 911                 return -1;
 912         }
 913
 914
 915         if (tdb->transaction->nesting != 0) {
 916                 tdb->transaction->nesting--;
 917                 return 0;
 918         }
 919
 920         /* check for a null transaction */
 921         if (tdb->transaction->blocks == NULL) {
 922                 return 0;
 923         }
 924
 925         methods = tdb->transaction->io_methods;
 926
 927         /* if there are any locks pending then the caller has not
 928            nested their locks properly, so fail the transaction */
 929         if (tdb_have_extra_locks(tdb)) {
 930                 tdb->ecode = TDB_ERR_LOCK;
 931                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: locks pending on commit\n"));
 932                 _tdb_transaction_cancel(tdb);
 933                 return -1;
 934         }
 935
 936         /* upgrade the main transaction lock region to a write lock */
 937         if (tdb_allrecord_upgrade(tdb) == -1) {
 938                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to upgrade hash locks\n"));
 939                 _tdb_transaction_cancel(tdb);
 940                 return -1;
 941         }
 942
 943         /* get the open lock - this prevents new users attaching to the database
 944            during the commit */
 945         if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
 946                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_prepare_commit: failed to get open lock\n"));
 947                 _tdb_transaction_cancel(tdb);
 948                 return -1;
 949         }
 950
 951         if (!(tdb->flags & TDB_NOSYNC)) {
 952                 /* write the recovery data to the end of the file */
 953                 if (transaction_setup_recovery(tdb, &tdb->transaction->magic_offset) == -1) {
 954                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: failed to setup recovery data\n"));
 955                         _tdb_transaction_cancel(tdb);
 956                         return -1;
 957                 }
 958         }
 959
 960         tdb->transaction->prepared = true;
 961
 962         /* expand the file to the new size if needed */
 963         if (tdb->map_size != tdb->transaction->old_map_size) {
 964                 if (methods->tdb_expand_file(tdb, tdb->transaction->old_map_size,
 965                                              tdb->map_size -
 966                                              tdb->transaction->old_map_size) == -1) {
 967                         tdb->ecode = TDB_ERR_IO;
 968                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_prepare_commit: expansion failed\n"));
 969                         _tdb_transaction_cancel(tdb);
 970                         return -1;
 971                 }
 972                 tdb->map_size = tdb->transaction->old_map_size;
 973                 methods->tdb_oob(tdb, tdb->map_size + 1, 1);
 974         }
 975
 976         /* Keep the open lock until the actual commit */
 977
 978         return 0;
 979 }
 980
 981 /*
 982    prepare to commit the current transaction
 983 */
 984 int tdb_transaction_prepare_commit(struct tdb_context *tdb)
 985 {
 986         tdb_trace(tdb, "tdb_transaction_prepare_commit");
 987         return _tdb_transaction_prepare_commit(tdb);
 988 }
 989
 990 /*
 991   commit the current transaction
 992 */
 993 int tdb_transaction_commit(struct tdb_context *tdb)
 994 {
 995         const struct tdb_methods *methods;
 996         int i;
 997         bool need_repack;
 998
 999         if (tdb->transaction == NULL) {
1000                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: no transaction\n"));
1001                 return -1;
1002         }
1003
1004         tdb_trace(tdb, "tdb_transaction_commit");
1005
1006         if (tdb->transaction->transaction_error) {
1007                 tdb->ecode = TDB_ERR_IO;
1008                 tdb_transaction_cancel(tdb);
1009                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_transaction_commit: transaction error pending\n"));
1010                 return -1;
1011         }
1012
1013
1014         if (tdb->transaction->nesting != 0) {
1015                 tdb->transaction->nesting--;
1016                 return 0;
1017         }
1018
1019         /* check for a null transaction */
1020         if (tdb->transaction->blocks == NULL) {
1021                 _tdb_transaction_cancel(tdb);
1022                 return 0;
1023         }
1024
1025         if (!tdb->transaction->prepared) {
1026                 int ret = _tdb_transaction_prepare_commit(tdb);
1027                 if (ret)
1028                         return ret;
1029         }
1030
1031         methods = tdb->transaction->io_methods;
1032
1033         /* perform all the writes */
1034         for (i=0;i<tdb->transaction->num_blocks;i++) {
1035                 tdb_off_t offset;
1036                 tdb_len_t length;
1037
1038                 if (tdb->transaction->blocks[i] == NULL) {
1039                         continue;
1040                 }
1041
1042                 offset = i * tdb->transaction->block_size;
1043                 length = tdb->transaction->block_size;
1044                 if (i == tdb->transaction->num_blocks-1) {
1045                         length = tdb->transaction->last_block_size;
1046                 }
1047
1048                 if (methods->tdb_write(tdb, offset, tdb->transaction->blocks[i], length) == -1) {
1049                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed during commit\n"));
1050
1051                         /* we've overwritten part of the data and
1052                            possibly expanded the file, so we need to
1053                            run the crash recovery code */
1054                         tdb->methods = methods;
1055                         tdb_transaction_recover(tdb);
1056
1057                         _tdb_transaction_cancel(tdb);
1058
1059                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_commit: write failed\n"));
1060                         return -1;
1061                 }
1062                 SAFE_FREE(tdb->transaction->blocks[i]);
1063         }
1064
1065         SAFE_FREE(tdb->transaction->blocks);
1066         tdb->transaction->num_blocks = 0;
1067
1068         /* ensure the new data is on disk */
1069         if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1070                 return -1;
1071         }
1072
1073         /*
1074           TODO: maybe write to some dummy hdr field, or write to magic
1075           offset without mmap, before the last sync, instead of the
1076           utime() call
1077         */
1078
1079         /* on some systems (like Linux 2.6.x) changes via mmap/msync
1080            don't change the mtime of the file, this means the file may
1081            not be backed up (as tdb rounding to block sizes means that
1082            file size changes are quite rare too). The following forces
1083            mtime changes when a transaction completes */
1084 #if HAVE_UTIME
1085         utime(tdb->name, NULL);
1086 #endif
1087
1088         need_repack = tdb->transaction->need_repack;
1089
1090         /* use a transaction cancel to free memory and remove the
1091            transaction locks */
1092         _tdb_transaction_cancel(tdb);
1093
1094         if (need_repack) {
1095                 return tdb_repack(tdb);
1096         }
1097
1098         return 0;
1099 }
1100
1101
1102 /*
1103   recover from an aborted transaction. Must be called with exclusive
1104   database write access already established (including the open
1105   lock to prevent new processes attaching)
1106 */
1107 int tdb_transaction_recover(struct tdb_context *tdb)
1108 {
1109         tdb_off_t recovery_head, recovery_eof;
1110         unsigned char *data, *p;
1111         uint32_t zero = 0;
1112         struct tdb_record rec;
1113
1114         /* find the recovery area */
1115         if (tdb_ofs_read(tdb, TDB_RECOVERY_HEAD, &recovery_head) == -1) {
1116                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery head\n"));
1117                 tdb->ecode = TDB_ERR_IO;
1118                 return -1;
1119         }
1120
1121         if (recovery_head == 0) {
1122                 /* we have never allocated a recovery record */
1123                 return 0;
1124         }
1125
1126         /* read the recovery record */
1127         if (tdb->methods->tdb_read(tdb, recovery_head, &rec,
1128                                    sizeof(rec), DOCONV()) == -1) {
1129                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery record\n"));
1130                 tdb->ecode = TDB_ERR_IO;
1131                 return -1;
1132         }
1133
1134         if (rec.magic != TDB_RECOVERY_MAGIC) {
1135                 /* there is no valid recovery data */
1136                 return 0;
1137         }
1138
1139         if (tdb->read_only) {
1140                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: attempt to recover read only database\n"));
1141                 tdb->ecode = TDB_ERR_CORRUPT;
1142                 return -1;
1143         }
1144
1145         recovery_eof = rec.key_len;
1146
1147         data = (unsigned char *)malloc(rec.data_len);
1148         if (data == NULL) {
1149                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to allocate recovery data\n"));
1150                 tdb->ecode = TDB_ERR_OOM;
1151                 return -1;
1152         }
1153
1154         /* read the full recovery data */
1155         if (tdb->methods->tdb_read(tdb, recovery_head + sizeof(rec), data,
1156                                    rec.data_len, 0) == -1) {
1157                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to read recovery data\n"));
1158                 tdb->ecode = TDB_ERR_IO;
1159                 return -1;
1160         }
1161
1162         /* recover the file data */
1163         p = data;
1164         while (p+8 < data + rec.data_len) {
1165                 uint32_t ofs, len;
1166                 if (DOCONV()) {
1167                         tdb_convert(p, 8);
1168                 }
1169                 memcpy(&ofs, p, 4);
1170                 memcpy(&len, p+4, 4);
1171
1172                 if (tdb->methods->tdb_write(tdb, ofs, p+8, len) == -1) {
1173                         free(data);
1174                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to recover %d bytes at offset %d\n", len, ofs));
1175                         tdb->ecode = TDB_ERR_IO;
1176                         return -1;
1177                 }
1178                 p += 8 + len;
1179         }
1180
1181         free(data);
1182
1183         if (transaction_sync(tdb, 0, tdb->map_size) == -1) {
1184                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync recovery\n"));
1185                 tdb->ecode = TDB_ERR_IO;
1186                 return -1;
1187         }
1188
1189         /* if the recovery area is after the recovered eof then remove it */
1190         if (recovery_eof <= recovery_head) {
1191                 if (tdb_ofs_write(tdb, TDB_RECOVERY_HEAD, &zero) == -1) {
1192                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery head\n"));
1193                         tdb->ecode = TDB_ERR_IO;
1194                         return -1;
1195                 }
1196         }
1197
1198         /* remove the recovery magic */
1199         if (tdb_ofs_write(tdb, recovery_head + offsetof(struct tdb_record, magic),
1200                           &zero) == -1) {
1201                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to remove recovery magic\n"));
1202                 tdb->ecode = TDB_ERR_IO;
1203                 return -1;
1204         }
1205
1206         /* reduce the file size to the old size */
1207         tdb_munmap(tdb);
1208         if (ftruncate(tdb->fd, recovery_eof) != 0) {
1209                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to reduce to recovery size\n"));
1210                 tdb->ecode = TDB_ERR_IO;
1211                 return -1;
1212         }
1213         tdb->map_size = recovery_eof;
1214         tdb_mmap(tdb);
1215
1216         if (transaction_sync(tdb, 0, recovery_eof) == -1) {
1217                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_transaction_recover: failed to sync2 recovery\n"));
1218                 tdb->ecode = TDB_ERR_IO;
1219                 return -1;
1220         }
1221
1222         TDB_LOG((tdb, TDB_DEBUG_TRACE, "tdb_transaction_recover: recovered %d byte database\n",
1223                  recovery_eof));
1224
1225         /* all done */
1226         return 0;
1227 }