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

   1 #include "private.h"
   2 #include <ccan/tdb2/tdb2.h>
   3 #include <ccan/hash/hash.h>
   4 #include <ccan/build_assert/build_assert.h>
   5 #include <ccan/likely/likely.h>
   6 #include <assert.h>
   7
   8 /* The null return. */
   9 struct tdb_data tdb_null = { .dptr = NULL, .dsize = 0 };
  10
  11 /* all contexts, to ensure no double-opens (fcntl locks don't nest!) */
  12 static struct tdb_context *tdbs = NULL;
  13
  14 PRINTF_ATTRIBUTE(4, 5) static void
  15 null_log_fn(struct tdb_context *tdb,
  16             enum tdb_debug_level level, void *priv,
  17             const char *fmt, ...)
  18 {
  19 }
  20
  21 /* We do a lot of work assuming our copy of the header volatile area
  22  * is uptodate, and usually it is.  However, once we grab a lock, we have to
  23  * re-check it. */
  24 bool header_changed(struct tdb_context *tdb)
  25 {
  26         uint64_t gen;
  27
  28         if (!(tdb->flags & TDB_NOLOCK) && tdb->header_uptodate) {
  29                 tdb->log(tdb, TDB_DEBUG_WARNING, tdb->log_priv,
  30                          "warning: header uptodate already\n");
  31         }
  32
  33         /* We could get a partial update if we're not holding any locks. */
  34         assert((tdb->flags & TDB_NOLOCK) || tdb_has_locks(tdb));
  35
  36         tdb->header_uptodate = true;
  37         gen = tdb_read_off(tdb, offsetof(struct tdb_header, v.generation));
  38         if (unlikely(gen != tdb->header.v.generation)) {
  39                 tdb_read_convert(tdb, offsetof(struct tdb_header, v),
  40                                  &tdb->header.v, sizeof(tdb->header.v));
  41                 return true;
  42         }
  43         return false;
  44 }
  45
  46 int write_header(struct tdb_context *tdb)
  47 {
  48         assert(tdb_read_off(tdb, offsetof(struct tdb_header, v.generation))
  49                == tdb->header.v.generation);
  50         tdb->header.v.generation++;
  51         return tdb_write_convert(tdb, offsetof(struct tdb_header, v),
  52                                  &tdb->header.v, sizeof(tdb->header.v));
  53 }
  54
  55 static uint64_t jenkins_hash(const void *key, size_t length, uint64_t seed,
  56                              void *arg)
  57 {
  58         return hash64_stable((const unsigned char *)key, length, seed);
  59 }
  60
  61 uint64_t tdb_hash(struct tdb_context *tdb, const void *ptr, size_t len)
  62 {
  63         return tdb->khash(ptr, len, tdb->header.hash_seed, tdb->hash_priv);
  64 }
  65
  66 static bool tdb_already_open(dev_t device, ino_t ino)
  67 {
  68         struct tdb_context *i;
  69
  70         for (i = tdbs; i; i = i->next) {
  71                 if (i->device == device && i->inode == ino) {
  72                         return true;
  73                 }
  74         }
  75
  76         return false;
  77 }
  78
  79 static uint64_t random_number(struct tdb_context *tdb)
  80 {
  81         int fd;
  82         uint64_t ret = 0;
  83         struct timeval now;
  84
  85         fd = open("/dev/urandom", O_RDONLY);
  86         if (fd >= 0) {
  87                 if (tdb_read_all(fd, &ret, sizeof(ret))) {
  88                         tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
  89                                  "tdb_open: random from /dev/urandom\n");
  90                         close(fd);
  91                         return ret;
  92                 }
  93                 close(fd);
  94         }
  95         /* FIXME: Untested!  Based on Wikipedia protocol description! */
  96         fd = open("/dev/egd-pool", O_RDWR);
  97         if (fd >= 0) {
  98                 /* Command is 1, next byte is size we want to read. */
  99                 char cmd[2] = { 1, sizeof(uint64_t) };
 100                 if (write(fd, cmd, sizeof(cmd)) == sizeof(cmd)) {
 101                         char reply[1 + sizeof(uint64_t)];
 102                         int r = read(fd, reply, sizeof(reply));
 103                         if (r > 1) {
 104                                 tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
 105                                          "tdb_open: %u random bytes from"
 106                                          " /dev/egd-pool\n", r-1);
 107                                 /* Copy at least some bytes. */
 108                                 memcpy(&ret, reply+1, r - 1);
 109                                 if (reply[0] == sizeof(uint64_t)
 110                                     && r == sizeof(reply)) {
 111                                         close(fd);
 112                                         return ret;
 113                                 }
 114                         }
 115                 }
 116                 close(fd);
 117         }
 118
 119         /* Fallback: pid and time. */
 120         gettimeofday(&now, NULL);
 121         ret = getpid() * 100132289ULL + now.tv_sec * 1000000ULL + now.tv_usec;
 122         tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
 123                  "tdb_open: random from getpid and time\n");
 124         return ret;
 125 }
 126
 127 struct new_database {
 128         struct tdb_header hdr;
 129         struct tdb_used_record hrec;
 130         tdb_off_t hash[1ULL << INITIAL_HASH_BITS];
 131         struct tdb_used_record frec;
 132         tdb_off_t free[INITIAL_FREE_BUCKETS + 1]; /* One overflow bucket */
 133 };
 134
 135 /* initialise a new database */
 136 static int tdb_new_database(struct tdb_context *tdb)
 137 {
 138         /* We make it up in memory, then write it out if not internal */
 139         struct new_database newdb;
 140         unsigned int magic_off = offsetof(struct tdb_header, magic_food);
 141
 142         /* Fill in the header */
 143         newdb.hdr.version = TDB_VERSION;
 144         newdb.hdr.hash_seed = random_number(tdb);
 145         newdb.hdr.hash_test = TDB_HASH_MAGIC;
 146         newdb.hdr.hash_test = tdb->khash(&newdb.hdr.hash_test,
 147                                          sizeof(newdb.hdr.hash_test),
 148                                          newdb.hdr.hash_seed,
 149                                          tdb->hash_priv);
 150
 151         newdb.hdr.v.generation = 0;
 152
 153         /* The initial zone must cover the initial database size! */
 154         BUILD_ASSERT((1ULL << INITIAL_ZONE_BITS) >= sizeof(newdb));
 155
 156         /* Free array has 1 zone, 10 buckets.  All buckets empty. */
 157         newdb.hdr.v.num_zones = 1;
 158         newdb.hdr.v.zone_bits = INITIAL_ZONE_BITS;
 159         newdb.hdr.v.free_buckets = INITIAL_FREE_BUCKETS;
 160         newdb.hdr.v.free_off = offsetof(struct new_database, free);
 161         set_header(tdb, &newdb.frec, 0,
 162                    sizeof(newdb.free), sizeof(newdb.free), 0);
 163         memset(newdb.free, 0, sizeof(newdb.free));
 164
 165         /* Initial hashes are empty. */
 166         newdb.hdr.v.hash_bits = INITIAL_HASH_BITS;
 167         newdb.hdr.v.hash_off = offsetof(struct new_database, hash);
 168         set_header(tdb, &newdb.hrec, 0,
 169                    sizeof(newdb.hash), sizeof(newdb.hash), 0);
 170         memset(newdb.hash, 0, sizeof(newdb.hash));
 171
 172         /* Magic food */
 173         memset(newdb.hdr.magic_food, 0, sizeof(newdb.hdr.magic_food));
 174         strcpy(newdb.hdr.magic_food, TDB_MAGIC_FOOD);
 175
 176         /* This creates an endian-converted database, as if read from disk */
 177         tdb_convert(tdb,
 178                     (char *)&newdb.hdr + magic_off,
 179                     sizeof(newdb) - magic_off);
 180
 181         tdb->header = newdb.hdr;
 182
 183         if (tdb->flags & TDB_INTERNAL) {
 184                 tdb->map_size = sizeof(newdb);
 185                 tdb->map_ptr = malloc(tdb->map_size);
 186                 if (!tdb->map_ptr) {
 187                         tdb->ecode = TDB_ERR_OOM;
 188                         return -1;
 189                 }
 190                 memcpy(tdb->map_ptr, &newdb, tdb->map_size);
 191                 return 0;
 192         }
 193         if (lseek(tdb->fd, 0, SEEK_SET) == -1)
 194                 return -1;
 195
 196         if (ftruncate(tdb->fd, 0) == -1)
 197                 return -1;
 198
 199         if (!tdb_pwrite_all(tdb->fd, &newdb, sizeof(newdb), 0)) {
 200                 tdb->ecode = TDB_ERR_IO;
 201                 return -1;
 202         }
 203         return 0;
 204 }
 205
 206 struct tdb_context *tdb_open(const char *name, int tdb_flags,
 207                              int open_flags, mode_t mode,
 208                              union tdb_attribute *attr)
 209 {
 210         struct tdb_context *tdb;
 211         struct stat st;
 212         int save_errno;
 213         uint64_t hash_test;
 214         unsigned v;
 215
 216         tdb = malloc(sizeof(*tdb));
 217         if (!tdb) {
 218                 /* Can't log this */
 219                 errno = ENOMEM;
 220                 goto fail;
 221         }
 222         tdb->name = NULL;
 223         tdb->map_ptr = NULL;
 224         tdb->fd = -1;
 225         /* map_size will be set below. */
 226         tdb->ecode = TDB_SUCCESS;
 227         /* header will be read in below. */
 228         tdb->header_uptodate = false;
 229         tdb->flags = tdb_flags;
 230         tdb->log = null_log_fn;
 231         tdb->log_priv = NULL;
 232         tdb->khash = jenkins_hash;
 233         tdb->hash_priv = NULL;
 234         tdb->transaction = NULL;
 235         /* last_zone will be set below. */
 236         tdb_io_init(tdb);
 237         tdb_lock_init(tdb);
 238
 239         /* FIXME */
 240         if (attr) {
 241                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 242                          "tdb_open: attributes not yet supported\n");
 243                 errno = EINVAL;
 244                 goto fail;
 245         }
 246
 247         if ((open_flags & O_ACCMODE) == O_WRONLY) {
 248                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 249                          "tdb_open: can't open tdb %s write-only\n", name);
 250                 errno = EINVAL;
 251                 goto fail;
 252         }
 253
 254         if ((open_flags & O_ACCMODE) == O_RDONLY) {
 255                 tdb->read_only = true;
 256                 /* read only databases don't do locking */
 257                 tdb->flags |= TDB_NOLOCK;
 258         } else
 259                 tdb->read_only = false;
 260
 261         /* internal databases don't need any of the rest. */
 262         if (tdb->flags & TDB_INTERNAL) {
 263                 tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
 264                 if (tdb_new_database(tdb) != 0) {
 265                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 266                                  "tdb_open: tdb_new_database failed!");
 267                         goto fail;
 268                 }
 269                 TEST_IT(tdb->flags & TDB_CONVERT);
 270                 tdb_convert(tdb, &tdb->header, sizeof(tdb->header));
 271                 return tdb;
 272         }
 273
 274         if ((tdb->fd = open(name, open_flags, mode)) == -1) {
 275                 tdb->log(tdb, TDB_DEBUG_WARNING, tdb->log_priv,
 276                          "tdb_open: could not open file %s: %s\n",
 277                          name, strerror(errno));
 278                 goto fail;      /* errno set by open(2) */
 279         }
 280
 281         /* on exec, don't inherit the fd */
 282         v = fcntl(tdb->fd, F_GETFD, 0);
 283         fcntl(tdb->fd, F_SETFD, v | FD_CLOEXEC);
 284
 285         /* ensure there is only one process initialising at once */
 286         if (tdb_lock_open(tdb) == -1) {
 287                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 288                          "tdb_open: failed to get open lock on %s: %s\n",
 289                          name, strerror(errno));
 290                 goto fail;      /* errno set by tdb_brlock */
 291         }
 292
 293         if (!tdb_pread_all(tdb->fd, &tdb->header, sizeof(tdb->header), 0)
 294             || strcmp(tdb->header.magic_food, TDB_MAGIC_FOOD) != 0) {
 295                 if (!(open_flags & O_CREAT) || tdb_new_database(tdb) == -1) {
 296                         if (errno == 0) {
 297                                 errno = EIO; /* ie bad format or something */
 298                         }
 299                         goto fail;
 300                 }
 301         } else if (tdb->header.version != TDB_VERSION) {
 302                 if (tdb->header.version == bswap_64(TDB_VERSION))
 303                         tdb->flags |= TDB_CONVERT;
 304                 else {
 305                         /* wrong version */
 306                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 307                                  "tdb_open: %s is unknown version 0x%llx\n",
 308                                  name, (long long)tdb->header.version);
 309                         errno = EIO;
 310                         goto fail;
 311                 }
 312         }
 313
 314         tdb_convert(tdb, &tdb->header, sizeof(tdb->header));
 315         hash_test = TDB_HASH_MAGIC;
 316         hash_test = tdb->khash(&hash_test, sizeof(hash_test),
 317                                tdb->header.hash_seed, tdb->hash_priv);
 318         if (tdb->header.hash_test != hash_test) {
 319                 /* wrong hash variant */
 320                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 321                          "tdb_open: %s uses a different hash function\n",
 322                          name);
 323                 errno = EIO;
 324                 goto fail;
 325         }
 326
 327         if (fstat(tdb->fd, &st) == -1)
 328                 goto fail;
 329
 330         /* Is it already in the open list?  If so, fail. */
 331         if (tdb_already_open(st.st_dev, st.st_ino)) {
 332                 /* FIXME */
 333                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 334                          "tdb_open: %s (%d,%d) is already open in this process\n",
 335                          name, (int)st.st_dev, (int)st.st_ino);
 336                 errno = EBUSY;
 337                 goto fail;
 338         }
 339
 340         tdb->name = strdup(name);
 341         if (!tdb->name) {
 342                 errno = ENOMEM;
 343                 goto fail;
 344         }
 345
 346         tdb->map_size = st.st_size;
 347         tdb->device = st.st_dev;
 348         tdb->inode = st.st_ino;
 349         tdb_mmap(tdb);
 350         tdb_unlock_open(tdb);
 351         tdb_zone_init(tdb);
 352
 353         tdb->next = tdbs;
 354         tdbs = tdb;
 355         return tdb;
 356
 357  fail:
 358         save_errno = errno;
 359
 360         if (!tdb)
 361                 return NULL;
 362
 363 #ifdef TDB_TRACE
 364         close(tdb->tracefd);
 365 #endif
 366         if (tdb->map_ptr) {
 367                 if (tdb->flags & TDB_INTERNAL) {
 368                         free(tdb->map_ptr);
 369                 } else
 370                         tdb_munmap(tdb);
 371         }
 372         free((char *)tdb->name);
 373         if (tdb->fd != -1)
 374                 if (close(tdb->fd) != 0)
 375                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 376                                  "tdb_open: failed to close tdb->fd"
 377                                  " on error!\n");
 378         free(tdb);
 379         errno = save_errno;
 380         return NULL;
 381 }
 382
 383 static tdb_off_t hash_off(struct tdb_context *tdb, uint64_t list)
 384 {
 385         return tdb->header.v.hash_off
 386                 + ((list & ((1ULL << tdb->header.v.hash_bits) - 1))
 387                    * sizeof(tdb_off_t));
 388 }
 389
 390 /* Returns 0 if the entry is a zero (definitely not a match).
 391  * Returns a valid entry offset if it's a match.  Fills in rec.
 392  * Otherwise returns TDB_OFF_ERR: keep searching. */
 393 static tdb_off_t entry_matches(struct tdb_context *tdb,
 394                                uint64_t list,
 395                                uint64_t hash,
 396                                const struct tdb_data *key,
 397                                struct tdb_used_record *rec)
 398 {
 399         tdb_off_t off;
 400         uint64_t keylen;
 401         const unsigned char *rkey;
 402
 403         off = tdb_read_off(tdb, tdb->header.v.hash_off
 404                            + list * sizeof(tdb_off_t));
 405         if (off == 0 || off == TDB_OFF_ERR)
 406                 return off;
 407
 408 #if 0 /* FIXME: Check other bits. */
 409         unsigned int bits, bitmask, hoffextra;
 410         /* Bottom three bits show how many extra hash bits. */
 411         bits = (off & ((1 << TDB_EXTRA_HASHBITS_NUM) - 1)) + 1;
 412         bitmask = (1 << bits)-1;
 413         hoffextra = ((off >> TDB_EXTRA_HASHBITS_NUM) & bitmask);
 414         uint64_t hextra = hash >> tdb->header.v.hash_bits;
 415         if ((hextra & bitmask) != hoffextra)
 416                 return TDB_OFF_ERR;
 417         off &= ~...;
 418 #endif
 419
 420         if (tdb_read_convert(tdb, off, rec, sizeof(*rec)) == -1)
 421                 return TDB_OFF_ERR;
 422
 423         /* FIXME: check extra bits in header! */
 424         keylen = rec_key_length(rec);
 425         if (keylen != key->dsize)
 426                 return TDB_OFF_ERR;
 427
 428         rkey = tdb_access_read(tdb, off + sizeof(*rec), keylen);
 429         if (!rkey)
 430                 return TDB_OFF_ERR;
 431         if (memcmp(rkey, key->dptr, keylen) != 0)
 432                 off = TDB_OFF_ERR;
 433         tdb_access_release(tdb, rkey);
 434         return off;
 435 }
 436
 437 /* FIXME: Optimize? */
 438 static void unlock_range(struct tdb_context *tdb,
 439                          tdb_off_t list, tdb_len_t num,
 440                          int ltype)
 441 {
 442         tdb_off_t i;
 443
 444         for (i = list; i < list + num; i++)
 445                 tdb_unlock_list(tdb, i, ltype);
 446 }
 447
 448 /* FIXME: Optimize? */
 449 static int lock_range(struct tdb_context *tdb,
 450                       tdb_off_t list, tdb_len_t num,
 451                       int ltype)
 452 {
 453         tdb_off_t i;
 454
 455         for (i = list; i < list + num; i++) {
 456                 if (tdb_lock_list(tdb, i, ltype, TDB_LOCK_WAIT) != 0) {
 457                         unlock_range(tdb, list, i - list, ltype);
 458                         return -1;
 459                 }
 460         }
 461         return 0;
 462 }
 463
 464 /* We lock hashes up to the next empty offset.  We already hold the
 465  * lock on the start bucket, but we may need to release and re-grab
 466  * it.  If we fail, we hold no locks at all! */
 467 static tdb_len_t relock_hash_to_zero(struct tdb_context *tdb,
 468                                      tdb_off_t start, int ltype)
 469 {
 470         tdb_len_t num, len, pre_locks;
 471
 472 again:
 473         num = 1ULL << tdb->header.v.hash_bits;
 474         len = tdb_find_zero_off(tdb, hash_off(tdb, start), num - start);
 475         if (unlikely(len == num - start)) {
 476                 /* We hit the end of the hash range.  Drop lock: we have
 477                    to lock start of hash first. */
 478                 tdb_unlock_list(tdb, start, ltype);
 479                 /* Grab something, so header is stable. */
 480                 if (tdb_lock_list(tdb, 0, ltype, TDB_LOCK_WAIT))
 481                         return TDB_OFF_ERR;
 482                 len = tdb_find_zero_off(tdb, hash_off(tdb, 0), num);
 483                 if (lock_range(tdb, 1, len, ltype) == -1) {
 484                         tdb_unlock_list(tdb, 0, ltype);
 485                         return TDB_OFF_ERR;
 486                 }
 487                 pre_locks = len;
 488                 len = num - start;
 489         } else {
 490                 /* We already have lock on start. */
 491                 start++;
 492                 pre_locks = 0;
 493         }
 494         if (unlikely(lock_range(tdb, start, len, ltype) == -1)) {
 495                 if (pre_locks)
 496                         unlock_range(tdb, 0, pre_locks, ltype);
 497                 else
 498                         tdb_unlock_list(tdb, start, ltype);
 499                 return TDB_OFF_ERR;
 500         }
 501
 502         /* Now, did we lose the race, and it's not zero any more? */
 503         if (unlikely(tdb_read_off(tdb, hash_off(tdb, pre_locks + len)) != 0)) {
 504                 unlock_range(tdb, 0, pre_locks, ltype);
 505                 /* Leave the start locked, as expected. */
 506                 unlock_range(tdb, start + 1, len - 1, ltype);
 507                 goto again;
 508         }
 509
 510         return pre_locks + len;
 511 }
 512
 513 /* FIXME: modify, don't rewrite! */
 514 static int update_rec_hdr(struct tdb_context *tdb,
 515                           tdb_off_t off,
 516                           tdb_len_t keylen,
 517                           tdb_len_t datalen,
 518                           struct tdb_used_record *rec,
 519                           uint64_t h)
 520 {
 521         uint64_t room = rec_data_length(rec) + rec_extra_padding(rec);
 522
 523         if (set_header(tdb, rec, keylen, datalen, room - datalen, h))
 524                 return -1;
 525
 526         return tdb_write_convert(tdb, off, rec, sizeof(*rec));
 527 }
 528
 529 /* If we fail, others will try after us. */
 530 static void enlarge_hash(struct tdb_context *tdb)
 531 {
 532         tdb_off_t newoff, i;
 533         uint64_t h, num = 1ULL << tdb->header.v.hash_bits;
 534         struct tdb_used_record pad, *r;
 535
 536         /* FIXME: We should do this without holding locks throughout. */
 537         if (tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false) == -1)
 538                 return;
 539
 540         /* Someone else enlarged for us?  Nothing to do. */
 541         if ((1ULL << tdb->header.v.hash_bits) != num)
 542                 goto unlock;
 543
 544         newoff = alloc(tdb, 0, num * 2, 0, false);
 545         if (unlikely(newoff == TDB_OFF_ERR))
 546                 goto unlock;
 547         if (unlikely(newoff == 0)) {
 548                 if (tdb_expand(tdb, 0, num * 2, false) == -1)
 549                         goto unlock;
 550                 newoff = alloc(tdb, 0, num * 2, 0, false);
 551                 if (newoff == TDB_OFF_ERR || newoff == 0)
 552                         goto unlock;
 553         }
 554
 555         /* FIXME: If the space before is empty, we know this is in its ideal
 556          * location.  We can steal a bit from the pointer to avoid rehash. */
 557         for (i = tdb_find_nonzero_off(tdb, tdb->header.v.hash_off, num);
 558              i < num;
 559              i += tdb_find_nonzero_off(tdb, tdb->header.v.hash_off
 560                                        + i*sizeof(tdb_off_t), num - i)) {
 561                 tdb_off_t off;
 562                 off = tdb_read_off(tdb, tdb->header.v.hash_off
 563                                    + i*sizeof(tdb_off_t));
 564                 if (unlikely(off == TDB_OFF_ERR))
 565                         goto unlock;
 566                 if (unlikely(!off)) {
 567                         tdb->ecode = TDB_ERR_CORRUPT;
 568                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 569                                  "find_bucket_and_lock: zero hash bucket!\n");
 570                         goto unlock;
 571                 }
 572                 h = hash_record(tdb, off);
 573                 /* FIXME: Encode extra hash bits! */
 574                 if (tdb_write_off(tdb, newoff
 575                                   + (h & ((num * 2) - 1)) * sizeof(uint64_t),
 576                                   off) == -1)
 577                         goto unlock;
 578         }
 579
 580         /* Free up old hash. */
 581         r = tdb_get(tdb, tdb->header.v.hash_off, &pad, sizeof(*r));
 582         if (!r)
 583                 goto unlock;
 584         add_free_record(tdb, tdb->header.v.hash_off,
 585                         rec_data_length(r) + rec_extra_padding(r));
 586
 587         /* Now we write the modified header. */
 588         tdb->header.v.generation++;
 589         tdb->header.v.hash_bits++;
 590         tdb->header.v.hash_off = newoff;
 591         tdb_write_convert(tdb, offsetof(struct tdb_header, v),
 592                           &tdb->header.v, sizeof(tdb->header.v));
 593 unlock:
 594         tdb_allrecord_unlock(tdb, F_WRLCK);
 595 }
 596
 597 int tdb_store(struct tdb_context *tdb,
 598               struct tdb_data key, struct tdb_data dbuf, int flag)
 599 {
 600         tdb_off_t new_off, off, old_bucket, start, num_locks = 1;
 601         struct tdb_used_record rec;
 602         uint64_t h;
 603         bool growing = false;
 604
 605         h = tdb_hash(tdb, key.dptr, key.dsize);
 606
 607         /* FIXME: can we avoid locks for some fast paths? */
 608         start = tdb_lock_list(tdb, h, F_WRLCK, TDB_LOCK_WAIT);
 609         if (start == TDB_OFF_ERR)
 610                 return -1;
 611
 612         /* Fast path. */
 613         old_bucket = start;
 614         off = entry_matches(tdb, start, h, &key, &rec);
 615         if (unlikely(off == TDB_OFF_ERR)) {
 616                 /* Slow path, need to grab more locks and search. */
 617                 tdb_off_t i;
 618
 619                 /* Warning: this may drop the lock!  Does that on error. */
 620                 num_locks = relock_hash_to_zero(tdb, start, F_WRLCK);
 621                 if (num_locks == TDB_OFF_ERR)
 622                         return -1;
 623
 624                 for (i = start; i < start + num_locks; i++) {
 625                         off = entry_matches(tdb, i, h, &key, &rec);
 626                         /* Empty entry or we found it? */
 627                         if (off == 0 || off != TDB_OFF_ERR) {
 628                                 old_bucket = i;
 629                                 break;
 630                         }
 631                 }
 632                 if (i == start + num_locks)
 633                         off = 0;
 634         }
 635
 636         /* Now we have lock on this hash bucket. */
 637         if (flag == TDB_INSERT) {
 638                 if (off) {
 639                         tdb->ecode = TDB_ERR_EXISTS;
 640                         goto fail;
 641                 }
 642         } else {
 643                 if (off) {
 644                         if (rec_data_length(&rec) + rec_extra_padding(&rec)
 645                             >= dbuf.dsize) {
 646                                 new_off = off;
 647                                 if (update_rec_hdr(tdb, off,
 648                                                    key.dsize, dbuf.dsize,
 649                                                    &rec, h))
 650                                         goto fail;
 651                                 goto write;
 652                         }
 653                         /* FIXME: See if right record is free? */
 654                         /* Hint to allocator that we've realloced. */
 655                         growing = true;
 656                 } else {
 657                         if (flag == TDB_MODIFY) {
 658                                 /* if the record doesn't exist and we
 659                                    are in TDB_MODIFY mode then we should fail
 660                                    the store */
 661                                 tdb->ecode = TDB_ERR_NOEXIST;
 662                                 goto fail;
 663                         }
 664                 }
 665         }
 666
 667         /* Allocate a new record. */
 668         new_off = alloc(tdb, key.dsize, dbuf.dsize, h, growing);
 669         if (new_off == 0) {
 670                 unlock_range(tdb, start, num_locks, F_WRLCK);
 671                 /* Expand, then try again... */
 672                 if (tdb_expand(tdb, key.dsize, dbuf.dsize, growing) == -1)
 673                         return -1;
 674                 return tdb_store(tdb, key, dbuf, flag);
 675         }
 676
 677         /* We didn't like the existing one: remove it. */
 678         if (off) {
 679                 add_free_record(tdb, off, sizeof(struct tdb_used_record)
 680                                 + rec_key_length(&rec)
 681                                 + rec_data_length(&rec)
 682                                 + rec_extra_padding(&rec));
 683         }
 684
 685 write:
 686         /* FIXME: Encode extra hash bits! */
 687         if (tdb_write_off(tdb, hash_off(tdb, old_bucket), new_off) == -1)
 688                 goto fail;
 689
 690         off = new_off + sizeof(struct tdb_used_record);
 691         if (tdb->methods->write(tdb, off, key.dptr, key.dsize) == -1)
 692                 goto fail;
 693         off += key.dsize;
 694         if (tdb->methods->write(tdb, off, dbuf.dptr, dbuf.dsize) == -1)
 695                 goto fail;
 696
 697         /* FIXME: tdb_increment_seqnum(tdb); */
 698         unlock_range(tdb, start, num_locks, F_WRLCK);
 699
 700         /* FIXME: by simple simulation, this approximated 60% full.
 701          * Check in real case! */
 702         if (unlikely(num_locks > 4 * tdb->header.v.hash_bits - 31))
 703                 enlarge_hash(tdb);
 704
 705         return 0;
 706
 707 fail:
 708         unlock_range(tdb, start, num_locks, F_WRLCK);
 709         return -1;
 710 }
 711
 712 struct tdb_data tdb_fetch(struct tdb_context *tdb, struct tdb_data key)
 713 {
 714         tdb_off_t off, start, num_locks = 1;
 715         struct tdb_used_record rec;
 716         uint64_t h;
 717         struct tdb_data ret;
 718
 719         h = tdb_hash(tdb, key.dptr, key.dsize);
 720
 721         /* FIXME: can we avoid locks for some fast paths? */
 722         start = tdb_lock_list(tdb, h, F_RDLCK, TDB_LOCK_WAIT);
 723         if (start == TDB_OFF_ERR)
 724                 return tdb_null;
 725
 726         /* Fast path. */
 727         off = entry_matches(tdb, start, h, &key, &rec);
 728         if (unlikely(off == TDB_OFF_ERR)) {
 729                 /* Slow path, need to grab more locks and search. */
 730                 tdb_off_t i;
 731
 732                 /* Warning: this may drop the lock!  Does that on error. */
 733                 num_locks = relock_hash_to_zero(tdb, start, F_RDLCK);
 734                 if (num_locks == TDB_OFF_ERR)
 735                         return tdb_null;
 736
 737                 for (i = start; i < start + num_locks; i++) {
 738                         off = entry_matches(tdb, i, h, &key, &rec);
 739                         /* Empty entry or we found it? */
 740                         if (off == 0 || off != TDB_OFF_ERR)
 741                                 break;
 742                 }
 743                 if (i == start + num_locks)
 744                         off = 0;
 745         }
 746
 747         if (!off) {
 748                 unlock_range(tdb, start, num_locks, F_RDLCK);
 749                 tdb->ecode = TDB_ERR_NOEXIST;
 750                 return tdb_null;
 751         }
 752
 753         ret.dsize = rec_data_length(&rec);
 754         ret.dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
 755                                   ret.dsize);
 756         unlock_range(tdb, start, num_locks, F_RDLCK);
 757         return ret;
 758 }
 759
 760 static int hash_add(struct tdb_context *tdb, uint64_t h, tdb_off_t off)
 761 {
 762         tdb_off_t i, hoff, len, num;
 763
 764         /* Look for next space. */
 765         i = (h & ((1ULL << tdb->header.v.hash_bits) - 1));
 766         len = (1ULL << tdb->header.v.hash_bits) - i;
 767         num = tdb_find_zero_off(tdb, hash_off(tdb, i), len);
 768
 769         if (unlikely(num == len)) {
 770                 /* We wrapped.  Look through start of hash table. */
 771                 hoff = hash_off(tdb, 0);
 772                 len = (1ULL << tdb->header.v.hash_bits);
 773                 num = tdb_find_zero_off(tdb, hoff, len);
 774                 if (i == len) {
 775                         tdb->ecode = TDB_ERR_CORRUPT;
 776                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 777                                  "hash_add: full hash table!\n");
 778                         return -1;
 779                 }
 780         }
 781         /* FIXME: Encode extra hash bits! */
 782         return tdb_write_off(tdb, hash_off(tdb, i + num), off);
 783 }
 784
 785 int tdb_delete(struct tdb_context *tdb, struct tdb_data key)
 786 {
 787         tdb_off_t i, old_bucket, off, start, num_locks = 1;
 788         struct tdb_used_record rec;
 789         uint64_t h;
 790
 791         h = tdb_hash(tdb, key.dptr, key.dsize);
 792
 793         /* FIXME: can we avoid locks for some fast paths? */
 794         start = tdb_lock_list(tdb, h, F_WRLCK, TDB_LOCK_WAIT);
 795         if (start == TDB_OFF_ERR)
 796                 return -1;
 797
 798         /* Fast path. */
 799         old_bucket = start;
 800         off = entry_matches(tdb, start, h, &key, &rec);
 801         if (off && off != TDB_OFF_ERR) {
 802                 /* We can only really fastpath delete if next bucket
 803                  * is 0.  Note that we haven't locked it, but our lock
 804                  * on this bucket stops anyone overflowing into it
 805                  * while we look. */
 806                 if (tdb_read_off(tdb, hash_off(tdb, h+1)) == 0)
 807                         goto delete;
 808                 /* Slow path. */
 809                 off = TDB_OFF_ERR;
 810         }
 811
 812         if (unlikely(off == TDB_OFF_ERR)) {
 813                 /* Slow path, need to grab more locks and search. */
 814                 tdb_off_t i;
 815
 816                 /* Warning: this may drop the lock!  Does that on error. */
 817                 num_locks = relock_hash_to_zero(tdb, start, F_WRLCK);
 818                 if (num_locks == TDB_OFF_ERR)
 819                         return -1;
 820
 821                 for (i = start; i < start + num_locks; i++) {
 822                         off = entry_matches(tdb, i, h, &key, &rec);
 823                         /* Empty entry or we found it? */
 824                         if (off == 0 || off != TDB_OFF_ERR) {
 825                                 old_bucket = i;
 826                                 break;
 827                         }
 828                 }
 829                 if (i == start + num_locks)
 830                         off = 0;
 831         }
 832
 833         if (!off) {
 834                 unlock_range(tdb, start, num_locks, F_WRLCK);
 835                 tdb->ecode = TDB_ERR_NOEXIST;
 836                 return -1;
 837         }
 838
 839 delete:
 840         /* This actually unlinks it. */
 841         if (tdb_write_off(tdb, hash_off(tdb, old_bucket), 0) == -1)
 842                 goto unlock_err;
 843
 844         /* Rehash anything following. */
 845         for (i = old_bucket+1; i < h + num_locks; i++) {
 846                 tdb_off_t off2;
 847                 uint64_t h2;
 848
 849                 off2 = tdb_read_off(tdb, hash_off(tdb, i));
 850                 if (unlikely(off2 == TDB_OFF_ERR))
 851                         goto unlock_err;
 852
 853                 /* Maybe use a bit to indicate it is in ideal place? */
 854                 h2 = hash_record(tdb, off2);
 855                 /* Is it happy where it is? */
 856                 if ((h2 & ((1ULL << tdb->header.v.hash_bits)-1))
 857                     == (i & ((1ULL << tdb->header.v.hash_bits)-1)))
 858                         continue;
 859
 860                 /* Remove it. */
 861                 if (tdb_write_off(tdb, hash_off(tdb, i), 0) == -1)
 862                         goto unlock_err;
 863
 864                 /* Rehash it. */
 865                 if (hash_add(tdb, h2, off2) == -1)
 866                         goto unlock_err;
 867         }
 868
 869         /* Free the deleted entry. */
 870         if (add_free_record(tdb, off,
 871                             sizeof(struct tdb_used_record)
 872                             + rec_key_length(&rec)
 873                             + rec_data_length(&rec)
 874                             + rec_extra_padding(&rec)) != 0)
 875                 goto unlock_err;
 876
 877         unlock_range(tdb, start, num_locks, F_WRLCK);
 878         return 0;
 879
 880 unlock_err:
 881         unlock_range(tdb, start, num_locks, F_WRLCK);
 882         return -1;
 883 }
 884
 885 int tdb_close(struct tdb_context *tdb)
 886 {
 887         struct tdb_context **i;
 888         int ret = 0;
 889
 890         /* FIXME:
 891         if (tdb->transaction) {
 892                 tdb_transaction_cancel(tdb);
 893         }
 894         */
 895         tdb_trace(tdb, "tdb_close");
 896
 897         if (tdb->map_ptr) {
 898                 if (tdb->flags & TDB_INTERNAL)
 899                         free(tdb->map_ptr);
 900                 else
 901                         tdb_munmap(tdb);
 902         }
 903         free((char *)tdb->name);
 904         if (tdb->fd != -1) {
 905                 ret = close(tdb->fd);
 906                 tdb->fd = -1;
 907         }
 908         free(tdb->lockrecs);
 909
 910         /* Remove from contexts list */
 911         for (i = &tdbs; *i; i = &(*i)->next) {
 912                 if (*i == tdb) {
 913                         *i = tdb->next;
 914                         break;
 915                 }
 916         }
 917
 918 #ifdef TDB_TRACE
 919         close(tdb->tracefd);
 920 #endif
 921         free(tdb);
 922
 923         return ret;
 924 }
 925
 926 enum TDB_ERROR tdb_error(struct tdb_context *tdb)
 927 {
 928         return tdb->ecode;
 929 }