lib/tdb2/tdb.c

   1  /*
   2    Trivial Database 2: fetch, store and misc routines.
   3    Copyright (C) Rusty Russell 2010
   4
   5    This library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 3 of the License, or (at your option) any later version.
   9
  10    This library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  17 */
  18 #include "private.h"
  19 #ifndef HAVE_LIBREPLACE
  20 #include <ccan/asprintf/asprintf.h>
  21 #include <stdarg.h>
  22 #endif
  23
  24 static enum TDB_ERROR update_rec_hdr(struct tdb_context *tdb,
  25                                      tdb_off_t off,
  26                                      tdb_len_t keylen,
  27                                      tdb_len_t datalen,
  28                                      struct tdb_used_record *rec,
  29                                      uint64_t h)
  30 {
  31         uint64_t dataroom = rec_data_length(rec) + rec_extra_padding(rec);
  32         enum TDB_ERROR ecode;
  33
  34         ecode = set_header(tdb, rec, TDB_USED_MAGIC, keylen, datalen,
  35                            keylen + dataroom, h);
  36         if (ecode == TDB_SUCCESS) {
  37                 ecode = tdb_write_convert(tdb, off, rec, sizeof(*rec));
  38         }
  39         return ecode;
  40 }
  41
  42 static enum TDB_ERROR replace_data(struct tdb_context *tdb,
  43                                    struct hash_info *h,
  44                                    struct tdb_data key, struct tdb_data dbuf,
  45                                    tdb_off_t old_off, tdb_len_t old_room,
  46                                    bool growing)
  47 {
  48         tdb_off_t new_off;
  49         enum TDB_ERROR ecode;
  50
  51         /* Allocate a new record. */
  52         new_off = alloc(tdb, key.dsize, dbuf.dsize, h->h, TDB_USED_MAGIC,
  53                         growing);
  54         if (TDB_OFF_IS_ERR(new_off)) {
  55                 return TDB_OFF_TO_ERR(new_off);
  56         }
  57
  58         /* We didn't like the existing one: remove it. */
  59         if (old_off) {
  60                 tdb->stats.frees++;
  61                 ecode = add_free_record(tdb, old_off,
  62                                         sizeof(struct tdb_used_record)
  63                                         + key.dsize + old_room,
  64                                         TDB_LOCK_WAIT, true);
  65                 if (ecode == TDB_SUCCESS)
  66                         ecode = replace_in_hash(tdb, h, new_off);
  67         } else {
  68                 ecode = add_to_hash(tdb, h, new_off);
  69         }
  70         if (ecode != TDB_SUCCESS) {
  71                 return ecode;
  72         }
  73
  74         new_off += sizeof(struct tdb_used_record);
  75         ecode = tdb->tdb2.io->twrite(tdb, new_off, key.dptr, key.dsize);
  76         if (ecode != TDB_SUCCESS) {
  77                 return ecode;
  78         }
  79
  80         new_off += key.dsize;
  81         ecode = tdb->tdb2.io->twrite(tdb, new_off, dbuf.dptr, dbuf.dsize);
  82         if (ecode != TDB_SUCCESS) {
  83                 return ecode;
  84         }
  85
  86         if (tdb->flags & TDB_SEQNUM)
  87                 tdb_inc_seqnum(tdb);
  88
  89         return TDB_SUCCESS;
  90 }
  91
  92 static enum TDB_ERROR update_data(struct tdb_context *tdb,
  93                                   tdb_off_t off,
  94                                   struct tdb_data dbuf,
  95                                   tdb_len_t extra)
  96 {
  97         enum TDB_ERROR ecode;
  98
  99         ecode = tdb->tdb2.io->twrite(tdb, off, dbuf.dptr, dbuf.dsize);
 100         if (ecode == TDB_SUCCESS && extra) {
 101                 /* Put a zero in; future versions may append other data. */
 102                 ecode = tdb->tdb2.io->twrite(tdb, off + dbuf.dsize, "", 1);
 103         }
 104         if (tdb->flags & TDB_SEQNUM)
 105                 tdb_inc_seqnum(tdb);
 106
 107         return ecode;
 108 }
 109
 110 _PUBLIC_ enum TDB_ERROR tdb_store(struct tdb_context *tdb,
 111                          struct tdb_data key, struct tdb_data dbuf, int flag)
 112 {
 113         struct hash_info h;
 114         tdb_off_t off;
 115         tdb_len_t old_room = 0;
 116         struct tdb_used_record rec;
 117         enum TDB_ERROR ecode;
 118
 119         if (tdb->flags & TDB_VERSION1) {
 120                 if (tdb1_store(tdb, key, dbuf, flag) == -1)
 121                         return tdb->last_error;
 122                 return TDB_SUCCESS;
 123         }
 124
 125         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 126         if (TDB_OFF_IS_ERR(off)) {
 127                 return tdb->last_error = TDB_OFF_TO_ERR(off);
 128         }
 129
 130         /* Now we have lock on this hash bucket. */
 131         if (flag == TDB_INSERT) {
 132                 if (off) {
 133                         ecode = TDB_ERR_EXISTS;
 134                         goto out;
 135                 }
 136         } else {
 137                 if (off) {
 138                         old_room = rec_data_length(&rec)
 139                                 + rec_extra_padding(&rec);
 140                         if (old_room >= dbuf.dsize) {
 141                                 /* Can modify in-place.  Easy! */
 142                                 ecode = update_rec_hdr(tdb, off,
 143                                                        key.dsize, dbuf.dsize,
 144                                                        &rec, h.h);
 145                                 if (ecode != TDB_SUCCESS) {
 146                                         goto out;
 147                                 }
 148                                 ecode = update_data(tdb,
 149                                                     off + sizeof(rec)
 150                                                     + key.dsize, dbuf,
 151                                                     old_room - dbuf.dsize);
 152                                 if (ecode != TDB_SUCCESS) {
 153                                         goto out;
 154                                 }
 155                                 tdb_unlock_hashes(tdb, h.hlock_start,
 156                                                   h.hlock_range, F_WRLCK);
 157                                 return tdb->last_error = TDB_SUCCESS;
 158                         }
 159                 } else {
 160                         if (flag == TDB_MODIFY) {
 161                                 /* if the record doesn't exist and we
 162                                    are in TDB_MODIFY mode then we should fail
 163                                    the store */
 164                                 ecode = TDB_ERR_NOEXIST;
 165                                 goto out;
 166                         }
 167                 }
 168         }
 169
 170         /* If we didn't use the old record, this implies we're growing. */
 171         ecode = replace_data(tdb, &h, key, dbuf, off, old_room, off);
 172 out:
 173         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 174         return tdb->last_error = ecode;
 175 }
 176
 177 _PUBLIC_ enum TDB_ERROR tdb_append(struct tdb_context *tdb,
 178                           struct tdb_data key, struct tdb_data dbuf)
 179 {
 180         struct hash_info h;
 181         tdb_off_t off;
 182         struct tdb_used_record rec;
 183         tdb_len_t old_room = 0, old_dlen;
 184         unsigned char *newdata;
 185         struct tdb_data new_dbuf;
 186         enum TDB_ERROR ecode;
 187
 188         if (tdb->flags & TDB_VERSION1) {
 189                 if (tdb1_append(tdb, key, dbuf) == -1)
 190                         return tdb->last_error;
 191                 return TDB_SUCCESS;
 192         }
 193
 194         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 195         if (TDB_OFF_IS_ERR(off)) {
 196                 return tdb->last_error = TDB_OFF_TO_ERR(off);
 197         }
 198
 199         if (off) {
 200                 old_dlen = rec_data_length(&rec);
 201                 old_room = old_dlen + rec_extra_padding(&rec);
 202
 203                 /* Fast path: can append in place. */
 204                 if (rec_extra_padding(&rec) >= dbuf.dsize) {
 205                         ecode = update_rec_hdr(tdb, off, key.dsize,
 206                                                old_dlen + dbuf.dsize, &rec,
 207                                                h.h);
 208                         if (ecode != TDB_SUCCESS) {
 209                                 goto out;
 210                         }
 211
 212                         off += sizeof(rec) + key.dsize + old_dlen;
 213                         ecode = update_data(tdb, off, dbuf,
 214                                             rec_extra_padding(&rec));
 215                         goto out;
 216                 }
 217
 218                 /* Slow path. */
 219                 newdata = malloc(key.dsize + old_dlen + dbuf.dsize);
 220                 if (!newdata) {
 221                         ecode = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
 222                                            "tdb_append:"
 223                                            " failed to allocate %zu bytes",
 224                                            (size_t)(key.dsize + old_dlen
 225                                                     + dbuf.dsize));
 226                         goto out;
 227                 }
 228                 ecode = tdb->tdb2.io->tread(tdb, off + sizeof(rec) + key.dsize,
 229                                             newdata, old_dlen);
 230                 if (ecode != TDB_SUCCESS) {
 231                         goto out_free_newdata;
 232                 }
 233                 memcpy(newdata + old_dlen, dbuf.dptr, dbuf.dsize);
 234                 new_dbuf.dptr = newdata;
 235                 new_dbuf.dsize = old_dlen + dbuf.dsize;
 236         } else {
 237                 newdata = NULL;
 238                 new_dbuf = dbuf;
 239         }
 240
 241         /* If they're using tdb_append(), it implies they're growing record. */
 242         ecode = replace_data(tdb, &h, key, new_dbuf, off, old_room, true);
 243
 244 out_free_newdata:
 245         free(newdata);
 246 out:
 247         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 248         return tdb->last_error = ecode;
 249 }
 250
 251 _PUBLIC_ enum TDB_ERROR tdb_fetch(struct tdb_context *tdb, struct tdb_data key,
 252                          struct tdb_data *data)
 253 {
 254         tdb_off_t off;
 255         struct tdb_used_record rec;
 256         struct hash_info h;
 257         enum TDB_ERROR ecode;
 258
 259         if (tdb->flags & TDB_VERSION1)
 260                 return tdb1_fetch(tdb, key, data);
 261
 262         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 263         if (TDB_OFF_IS_ERR(off)) {
 264                 return tdb->last_error = TDB_OFF_TO_ERR(off);
 265         }
 266
 267         if (!off) {
 268                 ecode = TDB_ERR_NOEXIST;
 269         } else {
 270                 data->dsize = rec_data_length(&rec);
 271                 data->dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
 272                                             data->dsize);
 273                 if (TDB_PTR_IS_ERR(data->dptr)) {
 274                         ecode = TDB_PTR_ERR(data->dptr);
 275                 } else
 276                         ecode = TDB_SUCCESS;
 277         }
 278
 279         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 280         return tdb->last_error = ecode;
 281 }
 282
 283 _PUBLIC_ bool tdb_exists(struct tdb_context *tdb, TDB_DATA key)
 284 {
 285         tdb_off_t off;
 286         struct tdb_used_record rec;
 287         struct hash_info h;
 288
 289         if (tdb->flags & TDB_VERSION1) {
 290                 return tdb1_exists(tdb, key);
 291         }
 292
 293         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 294         if (TDB_OFF_IS_ERR(off)) {
 295                 tdb->last_error = TDB_OFF_TO_ERR(off);
 296                 return false;
 297         }
 298         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 299
 300         tdb->last_error = TDB_SUCCESS;
 301         return off ? true : false;
 302 }
 303
 304 _PUBLIC_ enum TDB_ERROR tdb_delete(struct tdb_context *tdb, struct tdb_data key)
 305 {
 306         tdb_off_t off;
 307         struct tdb_used_record rec;
 308         struct hash_info h;
 309         enum TDB_ERROR ecode;
 310
 311         if (tdb->flags & TDB_VERSION1) {
 312                 if (tdb1_delete(tdb, key) == -1)
 313                         return tdb->last_error;
 314                 return TDB_SUCCESS;
 315         }
 316
 317         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 318         if (TDB_OFF_IS_ERR(off)) {
 319                 return tdb->last_error = TDB_OFF_TO_ERR(off);
 320         }
 321
 322         if (!off) {
 323                 ecode = TDB_ERR_NOEXIST;
 324                 goto unlock;
 325         }
 326
 327         ecode = delete_from_hash(tdb, &h);
 328         if (ecode != TDB_SUCCESS) {
 329                 goto unlock;
 330         }
 331
 332         /* Free the deleted entry. */
 333         tdb->stats.frees++;
 334         ecode = add_free_record(tdb, off,
 335                                 sizeof(struct tdb_used_record)
 336                                 + rec_key_length(&rec)
 337                                 + rec_data_length(&rec)
 338                                 + rec_extra_padding(&rec),
 339                                 TDB_LOCK_WAIT, true);
 340
 341         if (tdb->flags & TDB_SEQNUM)
 342                 tdb_inc_seqnum(tdb);
 343
 344 unlock:
 345         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 346         return tdb->last_error = ecode;
 347 }
 348
 349 _PUBLIC_ unsigned int tdb_get_flags(struct tdb_context *tdb)
 350 {
 351         return tdb->flags;
 352 }
 353
 354 static bool inside_transaction(const struct tdb_context *tdb)
 355 {
 356         if (tdb->flags & TDB_VERSION1)
 357                 return tdb->tdb1.transaction != NULL;
 358         else
 359                 return tdb->tdb2.transaction != NULL;
 360 }
 361
 362 static bool readonly_changable(struct tdb_context *tdb, const char *caller)
 363 {
 364         if (inside_transaction(tdb)) {
 365                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 366                                              TDB_LOG_USE_ERROR,
 367                                              "%s: can't change"
 368                                              " TDB_RDONLY inside transaction",
 369                                              caller);
 370                 return false;
 371         }
 372         return true;
 373 }
 374
 375 _PUBLIC_ void tdb_add_flag(struct tdb_context *tdb, unsigned flag)
 376 {
 377         if (tdb->flags & TDB_INTERNAL) {
 378                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 379                                              TDB_LOG_USE_ERROR,
 380                                              "tdb_add_flag: internal db");
 381                 return;
 382         }
 383         switch (flag) {
 384         case TDB_NOLOCK:
 385                 tdb->flags |= TDB_NOLOCK;
 386                 break;
 387         case TDB_NOMMAP:
 388                 tdb->flags |= TDB_NOMMAP;
 389 #ifndef HAVE_INCOHERENT_MMAP
 390                 tdb_munmap(tdb->file);
 391 #endif
 392                 break;
 393         case TDB_NOSYNC:
 394                 tdb->flags |= TDB_NOSYNC;
 395                 break;
 396         case TDB_SEQNUM:
 397                 tdb->flags |= TDB_SEQNUM;
 398                 break;
 399         case TDB_ALLOW_NESTING:
 400                 tdb->flags |= TDB_ALLOW_NESTING;
 401                 break;
 402         case TDB_RDONLY:
 403                 if (readonly_changable(tdb, "tdb_add_flag"))
 404                         tdb->flags |= TDB_RDONLY;
 405                 break;
 406         default:
 407                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 408                                              TDB_LOG_USE_ERROR,
 409                                              "tdb_add_flag: Unknown flag %u",
 410                                              flag);
 411         }
 412 }
 413
 414 _PUBLIC_ void tdb_remove_flag(struct tdb_context *tdb, unsigned flag)
 415 {
 416         if (tdb->flags & TDB_INTERNAL) {
 417                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 418                                              TDB_LOG_USE_ERROR,
 419                                              "tdb_remove_flag: internal db");
 420                 return;
 421         }
 422         switch (flag) {
 423         case TDB_NOLOCK:
 424                 tdb->flags &= ~TDB_NOLOCK;
 425                 break;
 426         case TDB_NOMMAP:
 427                 tdb->flags &= ~TDB_NOMMAP;
 428 #ifndef HAVE_INCOHERENT_MMAP
 429                 /* If mmap incoherent, we were mmaping anyway. */
 430                 tdb_mmap(tdb);
 431 #endif
 432                 break;
 433         case TDB_NOSYNC:
 434                 tdb->flags &= ~TDB_NOSYNC;
 435                 break;
 436         case TDB_SEQNUM:
 437                 tdb->flags &= ~TDB_SEQNUM;
 438                 break;
 439         case TDB_ALLOW_NESTING:
 440                 tdb->flags &= ~TDB_ALLOW_NESTING;
 441                 break;
 442         case TDB_RDONLY:
 443                 if ((tdb->open_flags & O_ACCMODE) == O_RDONLY) {
 444                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 445                                                      TDB_LOG_USE_ERROR,
 446                                                      "tdb_remove_flag: can't"
 447                                                      " remove TDB_RDONLY on tdb"
 448                                                      " opened with O_RDONLY");
 449                         break;
 450                 }
 451                 if (readonly_changable(tdb, "tdb_remove_flag"))
 452                         tdb->flags &= ~TDB_RDONLY;
 453                 break;
 454         default:
 455                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 456                                              TDB_LOG_USE_ERROR,
 457                                              "tdb_remove_flag: Unknown flag %u",
 458                                              flag);
 459         }
 460 }
 461
 462 _PUBLIC_ const char *tdb_errorstr(enum TDB_ERROR ecode)
 463 {
 464         /* Gcc warns if you miss a case in the switch, so use that. */
 465         switch (TDB_ERR_TO_OFF(ecode)) {
 466         case TDB_ERR_TO_OFF(TDB_SUCCESS): return "Success";
 467         case TDB_ERR_TO_OFF(TDB_ERR_CORRUPT): return "Corrupt database";
 468         case TDB_ERR_TO_OFF(TDB_ERR_IO): return "IO Error";
 469         case TDB_ERR_TO_OFF(TDB_ERR_LOCK): return "Locking error";
 470         case TDB_ERR_TO_OFF(TDB_ERR_OOM): return "Out of memory";
 471         case TDB_ERR_TO_OFF(TDB_ERR_EXISTS): return "Record exists";
 472         case TDB_ERR_TO_OFF(TDB_ERR_EINVAL): return "Invalid parameter";
 473         case TDB_ERR_TO_OFF(TDB_ERR_NOEXIST): return "Record does not exist";
 474         case TDB_ERR_TO_OFF(TDB_ERR_RDONLY): return "write not permitted";
 475         }
 476         return "Invalid error code";
 477 }
 478
 479 _PUBLIC_ enum TDB_ERROR tdb_error(struct tdb_context *tdb)
 480 {
 481         return tdb->last_error;
 482 }
 483
 484 enum TDB_ERROR COLD tdb_logerr(struct tdb_context *tdb,
 485                                enum TDB_ERROR ecode,
 486                                enum tdb_log_level level,
 487                                const char *fmt, ...)
 488 {
 489         char *message;
 490         va_list ap;
 491         size_t len;
 492         /* tdb_open paths care about errno, so save it. */
 493         int saved_errno = errno;
 494
 495         if (!tdb->log_fn)
 496                 return ecode;
 497
 498         va_start(ap, fmt);
 499         len = vasprintf(&message, fmt, ap);
 500         va_end(ap);
 501
 502         if (len < 0) {
 503                 tdb->log_fn(tdb, TDB_LOG_ERROR, TDB_ERR_OOM,
 504                             "out of memory formatting message:", tdb->log_data);
 505                 tdb->log_fn(tdb, level, ecode, fmt, tdb->log_data);
 506         } else {
 507                 tdb->log_fn(tdb, level, ecode, message, tdb->log_data);
 508                 free(message);
 509         }
 510         errno = saved_errno;
 511         return ecode;
 512 }
 513
 514 _PUBLIC_ enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb,
 515                                  TDB_DATA key,
 516                                  enum TDB_ERROR (*parse)(TDB_DATA k,
 517                                                          TDB_DATA d,
 518                                                          void *data),
 519                                  void *data)
 520 {
 521         tdb_off_t off;
 522         struct tdb_used_record rec;
 523         struct hash_info h;
 524         enum TDB_ERROR ecode;
 525
 526         if (tdb->flags & TDB_VERSION1) {
 527                 return tdb->last_error = tdb1_parse_record(tdb, key, parse,
 528                                                            data);
 529         }
 530
 531         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 532         if (TDB_OFF_IS_ERR(off)) {
 533                 return tdb->last_error = TDB_OFF_TO_ERR(off);
 534         }
 535
 536         if (!off) {
 537                 ecode = TDB_ERR_NOEXIST;
 538         } else {
 539                 const void *dptr;
 540                 dptr = tdb_access_read(tdb, off + sizeof(rec) + key.dsize,
 541                                        rec_data_length(&rec), false);
 542                 if (TDB_PTR_IS_ERR(dptr)) {
 543                         ecode = TDB_PTR_ERR(dptr);
 544                 } else {
 545                         TDB_DATA d = tdb_mkdata(dptr, rec_data_length(&rec));
 546
 547                         ecode = parse(key, d, data);
 548                         tdb_access_release(tdb, dptr);
 549                 }
 550         }
 551
 552         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 553         return tdb->last_error = ecode;
 554 }
 555
 556 _PUBLIC_ const char *tdb_name(const struct tdb_context *tdb)
 557 {
 558         return tdb->name;
 559 }
 560
 561 _PUBLIC_ int64_t tdb_get_seqnum(struct tdb_context *tdb)
 562 {
 563         tdb_off_t off;
 564
 565         if (tdb->flags & TDB_VERSION1) {
 566                 tdb1_off_t val;
 567                 tdb->last_error = TDB_SUCCESS;
 568                 val = tdb1_get_seqnum(tdb);
 569
 570                 if (tdb->last_error != TDB_SUCCESS)
 571                         return TDB_ERR_TO_OFF(tdb->last_error);
 572                 else
 573                         return val;
 574         }
 575
 576         off = tdb_read_off(tdb, offsetof(struct tdb_header, seqnum));
 577         if (TDB_OFF_IS_ERR(off))
 578                 tdb->last_error = TDB_OFF_TO_ERR(off);
 579         else
 580                 tdb->last_error = TDB_SUCCESS;
 581         return off;
 582 }
 583
 584
 585 _PUBLIC_ int tdb_fd(const struct tdb_context *tdb)
 586 {
 587         return tdb->file->fd;
 588 }
 589
 590 struct traverse_state {
 591         enum TDB_ERROR error;
 592         struct tdb_context *dest_db;
 593 };
 594
 595 /*
 596   traverse function for repacking
 597  */
 598 static int repack_traverse(struct tdb_context *tdb, TDB_DATA key, TDB_DATA data,
 599                            struct traverse_state *state)
 600 {
 601         state->error = tdb_store(state->dest_db, key, data, TDB_INSERT);
 602         if (state->error != TDB_SUCCESS) {
 603                 return -1;
 604         }
 605         return 0;
 606 }
 607
 608 _PUBLIC_ enum TDB_ERROR tdb_repack(struct tdb_context *tdb)
 609 {
 610         struct tdb_context *tmp_db;
 611         struct traverse_state state;
 612
 613         state.error = tdb_transaction_start(tdb);
 614         if (state.error != TDB_SUCCESS) {
 615                 return state.error;
 616         }
 617
 618         tmp_db = tdb_open("tmpdb", TDB_INTERNAL, O_RDWR|O_CREAT, 0, NULL);
 619         if (tmp_db == NULL) {
 620                 state.error = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
 621                                          __location__
 622                                          " Failed to create tmp_db");
 623                 tdb_transaction_cancel(tdb);
 624                 return tdb->last_error = state.error;
 625         }
 626
 627         state.dest_db = tmp_db;
 628         if (tdb_traverse(tdb, repack_traverse, &state) < 0) {
 629                 goto fail;
 630         }
 631
 632         state.error = tdb_wipe_all(tdb);
 633         if (state.error != TDB_SUCCESS) {
 634                 goto fail;
 635         }
 636
 637         state.dest_db = tdb;
 638         if (tdb_traverse(tmp_db, repack_traverse, &state) < 0) {
 639                 goto fail;
 640         }
 641
 642         tdb_close(tmp_db);
 643         return tdb_transaction_commit(tdb);
 644
 645 fail:
 646         tdb_transaction_cancel(tdb);
 647         tdb_close(tmp_db);
 648         return state.error;
 649 }