git.ozlabs.org Git - ccan/blob - ccan/tdb2/tdb.c

   1 #include "private.h"
   2 #include <ccan/tdb2/tdb2.h>
   3 #include <ccan/build_assert/build_assert.h>
   4 #include <ccan/likely/likely.h>
   5 #include <assert.h>
   6
   7 /* The null return. */
   8 struct tdb_data tdb_null = { .dptr = NULL, .dsize = 0 };
   9
  10 /* all contexts, to ensure no double-opens (fcntl locks don't nest!) */
  11 static struct tdb_context *tdbs = NULL;
  12
  13 PRINTF_FMT(4, 5) static void
  14 null_log_fn(struct tdb_context *tdb,
  15             enum tdb_debug_level level, void *priv,
  16             const char *fmt, ...)
  17 {
  18 }
  19
  20 static bool tdb_already_open(dev_t device, ino_t ino)
  21 {
  22         struct tdb_context *i;
  23
  24         for (i = tdbs; i; i = i->next) {
  25                 if (i->device == device && i->inode == ino) {
  26                         return true;
  27                 }
  28         }
  29
  30         return false;
  31 }
  32
  33 static uint64_t random_number(struct tdb_context *tdb)
  34 {
  35         int fd;
  36         uint64_t ret = 0;
  37         struct timeval now;
  38
  39         fd = open("/dev/urandom", O_RDONLY);
  40         if (fd >= 0) {
  41                 if (tdb_read_all(fd, &ret, sizeof(ret))) {
  42                         tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
  43                                  "tdb_open: random from /dev/urandom\n");
  44                         close(fd);
  45                         return ret;
  46                 }
  47                 close(fd);
  48         }
  49         /* FIXME: Untested!  Based on Wikipedia protocol description! */
  50         fd = open("/dev/egd-pool", O_RDWR);
  51         if (fd >= 0) {
  52                 /* Command is 1, next byte is size we want to read. */
  53                 char cmd[2] = { 1, sizeof(uint64_t) };
  54                 if (write(fd, cmd, sizeof(cmd)) == sizeof(cmd)) {
  55                         char reply[1 + sizeof(uint64_t)];
  56                         int r = read(fd, reply, sizeof(reply));
  57                         if (r > 1) {
  58                                 tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
  59                                          "tdb_open: %u random bytes from"
  60                                          " /dev/egd-pool\n", r-1);
  61                                 /* Copy at least some bytes. */
  62                                 memcpy(&ret, reply+1, r - 1);
  63                                 if (reply[0] == sizeof(uint64_t)
  64                                     && r == sizeof(reply)) {
  65                                         close(fd);
  66                                         return ret;
  67                                 }
  68                         }
  69                 }
  70                 close(fd);
  71         }
  72
  73         /* Fallback: pid and time. */
  74         gettimeofday(&now, NULL);
  75         ret = getpid() * 100132289ULL + now.tv_sec * 1000000ULL + now.tv_usec;
  76         tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
  77                  "tdb_open: random from getpid and time\n");
  78         return ret;
  79 }
  80
  81 struct new_database {
  82         struct tdb_header hdr;
  83         /* Initial free zone. */
  84         struct free_zone_header zhdr;
  85         tdb_off_t free[BUCKETS_FOR_ZONE(INITIAL_ZONE_BITS) + 1];
  86 };
  87
  88 /* initialise a new database */
  89 static int tdb_new_database(struct tdb_context *tdb,
  90                             struct tdb_attribute_seed *seed,
  91                             struct tdb_header *hdr)
  92 {
  93         /* We make it up in memory, then write it out if not internal */
  94         struct new_database newdb;
  95         unsigned int magic_len;
  96
  97         /* Fill in the header */
  98         newdb.hdr.version = TDB_VERSION;
  99         if (seed)
 100                 newdb.hdr.hash_seed = seed->seed;
 101         else
 102                 newdb.hdr.hash_seed = random_number(tdb);
 103         newdb.hdr.hash_test = TDB_HASH_MAGIC;
 104         newdb.hdr.hash_test = tdb->khash(&newdb.hdr.hash_test,
 105                                          sizeof(newdb.hdr.hash_test),
 106                                          newdb.hdr.hash_seed,
 107                                          tdb->hash_priv);
 108         memset(newdb.hdr.reserved, 0, sizeof(newdb.hdr.reserved));
 109         /* Initial hashes are empty. */
 110         memset(newdb.hdr.hashtable, 0, sizeof(newdb.hdr.hashtable));
 111
 112         /* Free is empty. */
 113         newdb.zhdr.zone_bits = INITIAL_ZONE_BITS;
 114         memset(newdb.free, 0, sizeof(newdb.free));
 115
 116         /* Magic food */
 117         memset(newdb.hdr.magic_food, 0, sizeof(newdb.hdr.magic_food));
 118         strcpy(newdb.hdr.magic_food, TDB_MAGIC_FOOD);
 119
 120         /* This creates an endian-converted database, as if read from disk */
 121         magic_len = sizeof(newdb.hdr.magic_food);
 122         tdb_convert(tdb,
 123                     (char *)&newdb.hdr + magic_len, sizeof(newdb) - magic_len);
 124
 125         *hdr = newdb.hdr;
 126
 127         if (tdb->flags & TDB_INTERNAL) {
 128                 tdb->map_size = sizeof(newdb);
 129                 tdb->map_ptr = malloc(tdb->map_size);
 130                 if (!tdb->map_ptr) {
 131                         tdb->ecode = TDB_ERR_OOM;
 132                         return -1;
 133                 }
 134                 memcpy(tdb->map_ptr, &newdb, tdb->map_size);
 135                 return 0;
 136         }
 137         if (lseek(tdb->fd, 0, SEEK_SET) == -1)
 138                 return -1;
 139
 140         if (ftruncate(tdb->fd, 0) == -1)
 141                 return -1;
 142
 143         if (!tdb_pwrite_all(tdb->fd, &newdb, sizeof(newdb), 0)) {
 144                 tdb->ecode = TDB_ERR_IO;
 145                 return -1;
 146         }
 147         return 0;
 148 }
 149
 150 struct tdb_context *tdb_open(const char *name, int tdb_flags,
 151                              int open_flags, mode_t mode,
 152                              union tdb_attribute *attr)
 153 {
 154         struct tdb_context *tdb;
 155         struct stat st;
 156         int save_errno;
 157         uint64_t hash_test;
 158         unsigned v;
 159         struct tdb_header hdr;
 160         struct tdb_attribute_seed *seed = NULL;
 161
 162         tdb = malloc(sizeof(*tdb));
 163         if (!tdb) {
 164                 /* Can't log this */
 165                 errno = ENOMEM;
 166                 goto fail;
 167         }
 168         tdb->name = NULL;
 169         tdb->map_ptr = NULL;
 170         tdb->direct_access = 0;
 171         tdb->fd = -1;
 172         tdb->map_size = sizeof(struct tdb_header);
 173         tdb->ecode = TDB_SUCCESS;
 174         tdb->flags = tdb_flags;
 175         tdb->log = null_log_fn;
 176         tdb->log_priv = NULL;
 177         tdb->transaction = NULL;
 178         tdb_hash_init(tdb);
 179         /* last_zone will be set below. */
 180         tdb_io_init(tdb);
 181         tdb_lock_init(tdb);
 182
 183         while (attr) {
 184                 switch (attr->base.attr) {
 185                 case TDB_ATTRIBUTE_LOG:
 186                         tdb->log = attr->log.log_fn;
 187                         tdb->log_priv = attr->log.log_private;
 188                         break;
 189                 case TDB_ATTRIBUTE_HASH:
 190                         tdb->khash = attr->hash.hash_fn;
 191                         tdb->hash_priv = attr->hash.hash_private;
 192                         break;
 193                 case TDB_ATTRIBUTE_SEED:
 194                         seed = &attr->seed;
 195                         break;
 196                 default:
 197                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 198                                  "tdb_open: unknown attribute type %u\n",
 199                                  attr->base.attr);
 200                         errno = EINVAL;
 201                         goto fail;
 202                 }
 203                 attr = attr->base.next;
 204         }
 205
 206         if ((open_flags & O_ACCMODE) == O_WRONLY) {
 207                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 208                          "tdb_open: can't open tdb %s write-only\n", name);
 209                 errno = EINVAL;
 210                 goto fail;
 211         }
 212
 213         if ((open_flags & O_ACCMODE) == O_RDONLY) {
 214                 tdb->read_only = true;
 215                 /* read only databases don't do locking */
 216                 tdb->flags |= TDB_NOLOCK;
 217                 tdb->mmap_flags = PROT_READ;
 218         } else {
 219                 tdb->read_only = false;
 220                 tdb->mmap_flags = PROT_READ | PROT_WRITE;
 221         }
 222
 223         /* internal databases don't need any of the rest. */
 224         if (tdb->flags & TDB_INTERNAL) {
 225                 tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
 226                 if (tdb_new_database(tdb, seed, &hdr) != 0) {
 227                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 228                                  "tdb_open: tdb_new_database failed!");
 229                         goto fail;
 230                 }
 231                 tdb_convert(tdb, &hdr.hash_seed, sizeof(hdr.hash_seed));
 232                 tdb->hash_seed = hdr.hash_seed;
 233                 tdb_zone_init(tdb);
 234                 return tdb;
 235         }
 236
 237         if ((tdb->fd = open(name, open_flags, mode)) == -1) {
 238                 tdb->log(tdb, TDB_DEBUG_WARNING, tdb->log_priv,
 239                          "tdb_open: could not open file %s: %s\n",
 240                          name, strerror(errno));
 241                 goto fail;      /* errno set by open(2) */
 242         }
 243
 244         /* on exec, don't inherit the fd */
 245         v = fcntl(tdb->fd, F_GETFD, 0);
 246         fcntl(tdb->fd, F_SETFD, v | FD_CLOEXEC);
 247
 248         /* ensure there is only one process initialising at once */
 249         if (tdb_lock_open(tdb) == -1) {
 250                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 251                          "tdb_open: failed to get open lock on %s: %s\n",
 252                          name, strerror(errno));
 253                 goto fail;      /* errno set by tdb_brlock */
 254         }
 255
 256         if (!tdb_pread_all(tdb->fd, &hdr, sizeof(hdr), 0)
 257             || strcmp(hdr.magic_food, TDB_MAGIC_FOOD) != 0) {
 258                 if (!(open_flags & O_CREAT)
 259                     || tdb_new_database(tdb, seed, &hdr) == -1) {
 260                         if (errno == 0) {
 261                                 errno = EIO; /* ie bad format or something */
 262                         }
 263                         goto fail;
 264                 }
 265         } else if (hdr.version != TDB_VERSION) {
 266                 if (hdr.version == bswap_64(TDB_VERSION))
 267                         tdb->flags |= TDB_CONVERT;
 268                 else {
 269                         /* wrong version */
 270                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 271                                  "tdb_open: %s is unknown version 0x%llx\n",
 272                                  name, (long long)hdr.version);
 273                         errno = EIO;
 274                         goto fail;
 275                 }
 276         }
 277
 278         tdb_convert(tdb, &hdr, sizeof(hdr));
 279         tdb->hash_seed = hdr.hash_seed;
 280         hash_test = TDB_HASH_MAGIC;
 281         hash_test = tdb_hash(tdb, &hash_test, sizeof(hash_test));
 282         if (hdr.hash_test != hash_test) {
 283                 /* wrong hash variant */
 284                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 285                          "tdb_open: %s uses a different hash function\n",
 286                          name);
 287                 errno = EIO;
 288                 goto fail;
 289         }
 290
 291         if (fstat(tdb->fd, &st) == -1)
 292                 goto fail;
 293
 294         /* Is it already in the open list?  If so, fail. */
 295         if (tdb_already_open(st.st_dev, st.st_ino)) {
 296                 /* FIXME */
 297                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 298                          "tdb_open: %s (%d,%d) is already open in this process\n",
 299                          name, (int)st.st_dev, (int)st.st_ino);
 300                 errno = EBUSY;
 301                 goto fail;
 302         }
 303
 304         tdb->name = strdup(name);
 305         if (!tdb->name) {
 306                 errno = ENOMEM;
 307                 goto fail;
 308         }
 309
 310         tdb->device = st.st_dev;
 311         tdb->inode = st.st_ino;
 312         tdb_unlock_open(tdb);
 313
 314         /* This make sure we have current map_size and mmap. */
 315         tdb->methods->oob(tdb, tdb->map_size + 1, true);
 316
 317         /* Now we can pick a random free zone to start from. */
 318         if (tdb_zone_init(tdb) == -1)
 319                 goto fail;
 320
 321         tdb->next = tdbs;
 322         tdbs = tdb;
 323         return tdb;
 324
 325  fail:
 326         save_errno = errno;
 327
 328         if (!tdb)
 329                 return NULL;
 330
 331 #ifdef TDB_TRACE
 332         close(tdb->tracefd);
 333 #endif
 334         if (tdb->map_ptr) {
 335                 if (tdb->flags & TDB_INTERNAL) {
 336                         free(tdb->map_ptr);
 337                 } else
 338                         tdb_munmap(tdb);
 339         }
 340         free((char *)tdb->name);
 341         if (tdb->fd != -1)
 342                 if (close(tdb->fd) != 0)
 343                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 344                                  "tdb_open: failed to close tdb->fd"
 345                                  " on error!\n");
 346         free(tdb);
 347         errno = save_errno;
 348         return NULL;
 349 }
 350
 351 /* FIXME: modify, don't rewrite! */
 352 static int update_rec_hdr(struct tdb_context *tdb,
 353                           tdb_off_t off,
 354                           tdb_len_t keylen,
 355                           tdb_len_t datalen,
 356                           struct tdb_used_record *rec,
 357                           uint64_t h)
 358 {
 359         uint64_t dataroom = rec_data_length(rec) + rec_extra_padding(rec);
 360
 361         if (set_header(tdb, rec, keylen, datalen, keylen + dataroom, h,
 362                        rec_zone_bits(rec)))
 363                 return -1;
 364
 365         return tdb_write_convert(tdb, off, rec, sizeof(*rec));
 366 }
 367
 368 /* Returns -1 on error, 0 on OK */
 369 static int replace_data(struct tdb_context *tdb,
 370                         struct hash_info *h,
 371                         struct tdb_data key, struct tdb_data dbuf,
 372                         tdb_off_t old_off, tdb_len_t old_room,
 373                         unsigned old_zone,
 374                         bool growing)
 375 {
 376         tdb_off_t new_off;
 377
 378         /* Allocate a new record. */
 379         new_off = alloc(tdb, key.dsize, dbuf.dsize, h->h, growing);
 380         if (unlikely(new_off == TDB_OFF_ERR))
 381                 return -1;
 382
 383         /* We didn't like the existing one: remove it. */
 384         if (old_off) {
 385                 add_free_record(tdb, old_zone, old_off,
 386                                 sizeof(struct tdb_used_record)
 387                                 + key.dsize + old_room);
 388                 if (replace_in_hash(tdb, h, new_off) == -1)
 389                         return -1;
 390         } else {
 391                 if (add_to_hash(tdb, h, new_off) == -1)
 392                         return -1;
 393         }
 394
 395         new_off += sizeof(struct tdb_used_record);
 396         if (tdb->methods->write(tdb, new_off, key.dptr, key.dsize) == -1)
 397                 return -1;
 398
 399         new_off += key.dsize;
 400         if (tdb->methods->write(tdb, new_off, dbuf.dptr, dbuf.dsize) == -1)
 401                 return -1;
 402
 403         /* FIXME: tdb_increment_seqnum(tdb); */
 404         return 0;
 405 }
 406
 407 int tdb_store(struct tdb_context *tdb,
 408               struct tdb_data key, struct tdb_data dbuf, int flag)
 409 {
 410         struct hash_info h;
 411         tdb_off_t off;
 412         tdb_len_t old_room = 0;
 413         struct tdb_used_record rec;
 414         int ret;
 415
 416         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 417         if (unlikely(off == TDB_OFF_ERR))
 418                 return -1;
 419
 420         /* Now we have lock on this hash bucket. */
 421         if (flag == TDB_INSERT) {
 422                 if (off) {
 423                         tdb->ecode = TDB_ERR_EXISTS;
 424                         goto fail;
 425                 }
 426         } else {
 427                 if (off) {
 428                         old_room = rec_data_length(&rec)
 429                                 + rec_extra_padding(&rec);
 430                         if (old_room >= dbuf.dsize) {
 431                                 /* Can modify in-place.  Easy! */
 432                                 if (update_rec_hdr(tdb, off,
 433                                                    key.dsize, dbuf.dsize,
 434                                                    &rec, h.h))
 435                                         goto fail;
 436                                 if (tdb->methods->write(tdb, off + sizeof(rec)
 437                                                         + key.dsize,
 438                                                         dbuf.dptr, dbuf.dsize))
 439                                         goto fail;
 440                                 tdb_unlock_hashes(tdb, h.hlock_start,
 441                                                   h.hlock_range, F_WRLCK);
 442                                 return 0;
 443                         }
 444                         /* FIXME: See if right record is free? */
 445                 } else {
 446                         if (flag == TDB_MODIFY) {
 447                                 /* if the record doesn't exist and we
 448                                    are in TDB_MODIFY mode then we should fail
 449                                    the store */
 450                                 tdb->ecode = TDB_ERR_NOEXIST;
 451                                 goto fail;
 452                         }
 453                 }
 454         }
 455
 456         /* If we didn't use the old record, this implies we're growing. */
 457         ret = replace_data(tdb, &h, key, dbuf, off, old_room,
 458                            rec_zone_bits(&rec), off != 0);
 459         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 460         return ret;
 461
 462 fail:
 463         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 464         return -1;
 465 }
 466
 467 int tdb_append(struct tdb_context *tdb,
 468                struct tdb_data key, struct tdb_data dbuf)
 469 {
 470         struct hash_info h;
 471         tdb_off_t off;
 472         struct tdb_used_record rec;
 473         tdb_len_t old_room = 0, old_dlen;
 474         unsigned char *newdata;
 475         struct tdb_data new_dbuf;
 476         int ret;
 477
 478         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 479         if (unlikely(off == TDB_OFF_ERR))
 480                 return -1;
 481
 482         if (off) {
 483                 old_dlen = rec_data_length(&rec);
 484                 old_room = old_dlen + rec_extra_padding(&rec);
 485
 486                 /* Fast path: can append in place. */
 487                 if (rec_extra_padding(&rec) >= dbuf.dsize) {
 488                         if (update_rec_hdr(tdb, off, key.dsize,
 489                                            old_dlen + dbuf.dsize, &rec, h.h))
 490                                 goto fail;
 491
 492                         off += sizeof(rec) + key.dsize + old_dlen;
 493                         if (tdb->methods->write(tdb, off, dbuf.dptr,
 494                                                 dbuf.dsize) == -1)
 495                                 goto fail;
 496
 497                         /* FIXME: tdb_increment_seqnum(tdb); */
 498                         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range,
 499                                           F_WRLCK);
 500                         return 0;
 501                 }
 502                 /* FIXME: Check right record free? */
 503
 504                 /* Slow path. */
 505                 newdata = malloc(key.dsize + old_dlen + dbuf.dsize);
 506                 if (!newdata) {
 507                         tdb->ecode = TDB_ERR_OOM;
 508                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 509                                  "tdb_append: cannot allocate %llu bytes!\n",
 510                                  (long long)key.dsize + old_dlen + dbuf.dsize);
 511                         goto fail;
 512                 }
 513                 if (tdb->methods->read(tdb, off + sizeof(rec) + key.dsize,
 514                                        newdata, old_dlen) != 0) {
 515                         free(newdata);
 516                         goto fail;
 517                 }
 518                 memcpy(newdata + old_dlen, dbuf.dptr, dbuf.dsize);
 519                 new_dbuf.dptr = newdata;
 520                 new_dbuf.dsize = old_dlen + dbuf.dsize;
 521         } else {
 522                 newdata = NULL;
 523                 new_dbuf = dbuf;
 524         }
 525
 526         /* If they're using tdb_append(), it implies they're growing record. */
 527         ret = replace_data(tdb, &h, key, new_dbuf, off,
 528                            old_room, rec_zone_bits(&rec), true);
 529         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 530         free(newdata);
 531
 532         return ret;
 533
 534 fail:
 535         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 536         return -1;
 537 }
 538
 539 struct tdb_data tdb_fetch(struct tdb_context *tdb, struct tdb_data key)
 540 {
 541         tdb_off_t off;
 542         struct tdb_used_record rec;
 543         struct hash_info h;
 544         struct tdb_data ret;
 545
 546         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 547         if (unlikely(off == TDB_OFF_ERR))
 548                 return tdb_null;
 549
 550         if (!off) {
 551                 tdb->ecode = TDB_ERR_NOEXIST;
 552                 ret = tdb_null;
 553         } else {
 554                 ret.dsize = rec_data_length(&rec);
 555                 ret.dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
 556                                           ret.dsize);
 557         }
 558
 559         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 560         return ret;
 561 }
 562
 563 int tdb_delete(struct tdb_context *tdb, struct tdb_data key)
 564 {
 565         tdb_off_t off;
 566         struct tdb_used_record rec;
 567         struct hash_info h;
 568
 569         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 570         if (unlikely(off == TDB_OFF_ERR))
 571                 return -1;
 572
 573         if (!off) {
 574                 tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 575                 tdb->ecode = TDB_ERR_NOEXIST;
 576                 return -1;
 577         }
 578
 579         if (delete_from_hash(tdb, &h) == -1)
 580                 goto unlock_err;
 581
 582         /* Free the deleted entry. */
 583         if (add_free_record(tdb, rec_zone_bits(&rec), off,
 584                             sizeof(struct tdb_used_record)
 585                             + rec_key_length(&rec)
 586                             + rec_data_length(&rec)
 587                             + rec_extra_padding(&rec)) != 0)
 588                 goto unlock_err;
 589
 590         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 591         return 0;
 592
 593 unlock_err:
 594         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 595         return -1;
 596 }
 597
 598 int tdb_close(struct tdb_context *tdb)
 599 {
 600         struct tdb_context **i;
 601         int ret = 0;
 602
 603         /* FIXME:
 604         if (tdb->transaction) {
 605                 tdb_transaction_cancel(tdb);
 606         }
 607         */
 608         tdb_trace(tdb, "tdb_close");
 609
 610         if (tdb->map_ptr) {
 611                 if (tdb->flags & TDB_INTERNAL)
 612                         free(tdb->map_ptr);
 613                 else
 614                         tdb_munmap(tdb);
 615         }
 616         free((char *)tdb->name);
 617         if (tdb->fd != -1) {
 618                 ret = close(tdb->fd);
 619                 tdb->fd = -1;
 620         }
 621         free(tdb->lockrecs);
 622
 623         /* Remove from contexts list */
 624         for (i = &tdbs; *i; i = &(*i)->next) {
 625                 if (*i == tdb) {
 626                         *i = tdb->next;
 627                         break;
 628                 }
 629         }
 630
 631 #ifdef TDB_TRACE
 632         close(tdb->tracefd);
 633 #endif
 634         free(tdb);
 635
 636         return ret;
 637 }
 638
 639 enum TDB_ERROR tdb_error(struct tdb_context *tdb)
 640 {
 641         return tdb->ecode;
 642 }
 643
 644 const char *tdb_errorstr(struct tdb_context *tdb)
 645 {
 646         /* Gcc warns if you miss a case in the switch, so use that. */
 647         switch (tdb->ecode) {
 648         case TDB_SUCCESS: return "Success";
 649         case TDB_ERR_CORRUPT: return "Corrupt database";
 650         case TDB_ERR_IO: return "IO Error";
 651         case TDB_ERR_LOCK: return "Locking error";
 652         case TDB_ERR_OOM: return "Out of memory";
 653         case TDB_ERR_EXISTS: return "Record exists";
 654         case TDB_ERR_NESTING: return "Transaction already started";
 655         case TDB_ERR_EINVAL: return "Invalid parameter";
 656         case TDB_ERR_NOEXIST: return "Record does not exist";
 657         case TDB_ERR_RDONLY: return "write not permitted";
 658         }
 659         return "Invalid error code";
 660 }