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, false);
 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_lists(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_lists(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_lists(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_lists(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_lists(tdb, start, len, ltype) == -1)) {
 495                 if (pre_locks)
 496                         unlock_lists(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_lists(tdb, 0, pre_locks, ltype);
 505                 /* Leave the start locked, as expected. */
 506                 unlock_lists(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, oldoff, i;
 533         tdb_len_t hlen;
 534         uint64_t h, num = 1ULL << tdb->header.v.hash_bits;
 535         struct tdb_used_record pad, *r;
 536
 537         /* FIXME: We should do this without holding locks throughout. */
 538         if (tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false) == -1)
 539                 return;
 540
 541         /* Someone else enlarged for us?  Nothing to do. */
 542         if ((1ULL << tdb->header.v.hash_bits) != num)
 543                 goto unlock;
 544
 545         /* Allocate our new array. */
 546         hlen = num * sizeof(tdb_off_t) * 2;
 547         newoff = alloc(tdb, 0, hlen, 0, false);
 548         if (unlikely(newoff == TDB_OFF_ERR))
 549                 goto unlock;
 550         if (unlikely(newoff == 0)) {
 551                 if (tdb_expand(tdb, 0, hlen, false) == -1)
 552                         goto unlock;
 553                 newoff = alloc(tdb, 0, hlen, 0, false);
 554                 if (newoff == TDB_OFF_ERR || newoff == 0)
 555                         goto unlock;
 556         }
 557         /* Step over record header! */
 558         newoff += sizeof(struct tdb_used_record);
 559
 560         /* Starts all zero. */
 561         if (zero_out(tdb, newoff, hlen) == -1)
 562                 goto unlock;
 563
 564         /* FIXME: If the space before is empty, we know this is in its ideal
 565          * location.  Or steal a bit from the pointer to avoid rehash. */
 566         for (i = tdb_find_nonzero_off(tdb, hash_off(tdb, 0), num);
 567              i < num;
 568              i += tdb_find_nonzero_off(tdb, hash_off(tdb, i), num - i)) {
 569                 tdb_off_t off;
 570                 off = tdb_read_off(tdb, hash_off(tdb, i));
 571                 if (unlikely(off == TDB_OFF_ERR))
 572                         goto unlock;
 573                 if (unlikely(!off)) {
 574                         tdb->ecode = TDB_ERR_CORRUPT;
 575                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 576                                  "find_bucket_and_lock: zero hash bucket!\n");
 577                         goto unlock;
 578                 }
 579                 h = hash_record(tdb, off);
 580                 /* FIXME: Encode extra hash bits! */
 581                 if (tdb_write_off(tdb, newoff
 582                                   + (h & ((num * 2) - 1)) * sizeof(uint64_t),
 583                                   off) == -1)
 584                         goto unlock;
 585         }
 586
 587         /* Free up old hash. */
 588         oldoff = tdb->header.v.hash_off - sizeof(*r);
 589         r = tdb_get(tdb, oldoff, &pad, sizeof(*r));
 590         if (!r)
 591                 goto unlock;
 592         add_free_record(tdb, oldoff,
 593                         sizeof(*r)+rec_data_length(r)+rec_extra_padding(r));
 594
 595         /* Now we write the modified header. */
 596         tdb->header.v.hash_bits++;
 597         tdb->header.v.hash_off = newoff;
 598         write_header(tdb);
 599 unlock:
 600         tdb_allrecord_unlock(tdb, F_WRLCK);
 601 }
 602
 603 int tdb_store(struct tdb_context *tdb,
 604               struct tdb_data key, struct tdb_data dbuf, int flag)
 605 {
 606         tdb_off_t new_off, off, old_bucket, start, num_locks = 1;
 607         struct tdb_used_record rec;
 608         uint64_t h;
 609         bool growing = false;
 610
 611         h = tdb_hash(tdb, key.dptr, key.dsize);
 612
 613         /* FIXME: can we avoid locks for some fast paths? */
 614         start = tdb_lock_list(tdb, h, F_WRLCK, TDB_LOCK_WAIT);
 615         if (start == TDB_OFF_ERR)
 616                 return -1;
 617
 618         /* Fast path. */
 619         old_bucket = start;
 620         off = entry_matches(tdb, start, h, &key, &rec);
 621         if (unlikely(off == TDB_OFF_ERR)) {
 622                 /* Slow path, need to grab more locks and search. */
 623                 tdb_off_t i;
 624
 625                 /* Warning: this may drop the lock!  Does that on error. */
 626                 num_locks = relock_hash_to_zero(tdb, start, F_WRLCK);
 627                 if (num_locks == TDB_OFF_ERR)
 628                         return -1;
 629
 630                 for (i = start; i < start + num_locks; i++) {
 631                         off = entry_matches(tdb, i, h, &key, &rec);
 632                         /* Empty entry or we found it? */
 633                         if (off == 0 || off != TDB_OFF_ERR) {
 634                                 old_bucket = i;
 635                                 break;
 636                         }
 637                 }
 638                 if (i == start + num_locks)
 639                         off = 0;
 640         }
 641
 642         /* Now we have lock on this hash bucket. */
 643         if (flag == TDB_INSERT) {
 644                 if (off) {
 645                         tdb->ecode = TDB_ERR_EXISTS;
 646                         goto fail;
 647                 }
 648         } else {
 649                 if (off) {
 650                         if (rec_data_length(&rec) + rec_extra_padding(&rec)
 651                             >= dbuf.dsize) {
 652                                 new_off = off;
 653                                 if (update_rec_hdr(tdb, off,
 654                                                    key.dsize, dbuf.dsize,
 655                                                    &rec, h))
 656                                         goto fail;
 657                                 goto write;
 658                         }
 659                         /* FIXME: See if right record is free? */
 660                         /* Hint to allocator that we've realloced. */
 661                         growing = true;
 662                 } else {
 663                         if (flag == TDB_MODIFY) {
 664                                 /* if the record doesn't exist and we
 665                                    are in TDB_MODIFY mode then we should fail
 666                                    the store */
 667                                 tdb->ecode = TDB_ERR_NOEXIST;
 668                                 goto fail;
 669                         }
 670                 }
 671         }
 672
 673         /* Allocate a new record. */
 674         new_off = alloc(tdb, key.dsize, dbuf.dsize, h, growing);
 675         if (new_off == 0) {
 676                 unlock_lists(tdb, start, num_locks, F_WRLCK);
 677                 /* Expand, then try again... */
 678                 if (tdb_expand(tdb, key.dsize, dbuf.dsize, growing) == -1)
 679                         return -1;
 680                 return tdb_store(tdb, key, dbuf, flag);
 681         }
 682
 683         /* We didn't like the existing one: remove it. */
 684         if (off) {
 685                 add_free_record(tdb, off, sizeof(struct tdb_used_record)
 686                                 + rec_key_length(&rec)
 687                                 + rec_data_length(&rec)
 688                                 + rec_extra_padding(&rec));
 689         }
 690
 691 write:
 692         /* FIXME: Encode extra hash bits! */
 693         if (tdb_write_off(tdb, hash_off(tdb, old_bucket), new_off) == -1)
 694                 goto fail;
 695
 696         off = new_off + sizeof(struct tdb_used_record);
 697         if (tdb->methods->write(tdb, off, key.dptr, key.dsize) == -1)
 698                 goto fail;
 699         off += key.dsize;
 700         if (tdb->methods->write(tdb, off, dbuf.dptr, dbuf.dsize) == -1)
 701                 goto fail;
 702
 703         /* FIXME: tdb_increment_seqnum(tdb); */
 704         unlock_lists(tdb, start, num_locks, F_WRLCK);
 705
 706         /* FIXME: by simple simulation, this approximated 60% full.
 707          * Check in real case! */
 708         if (unlikely(num_locks > 4 * tdb->header.v.hash_bits - 31))
 709                 enlarge_hash(tdb);
 710
 711         return 0;
 712
 713 fail:
 714         unlock_lists(tdb, start, num_locks, F_WRLCK);
 715         return -1;
 716 }
 717
 718 struct tdb_data tdb_fetch(struct tdb_context *tdb, struct tdb_data key)
 719 {
 720         tdb_off_t off, start, num_locks = 1;
 721         struct tdb_used_record rec;
 722         uint64_t h;
 723         struct tdb_data ret;
 724
 725         h = tdb_hash(tdb, key.dptr, key.dsize);
 726
 727         /* FIXME: can we avoid locks for some fast paths? */
 728         start = tdb_lock_list(tdb, h, F_RDLCK, TDB_LOCK_WAIT);
 729         if (start == TDB_OFF_ERR)
 730                 return tdb_null;
 731
 732         /* Fast path. */
 733         off = entry_matches(tdb, start, h, &key, &rec);
 734         if (unlikely(off == TDB_OFF_ERR)) {
 735                 /* Slow path, need to grab more locks and search. */
 736                 tdb_off_t i;
 737
 738                 /* Warning: this may drop the lock!  Does that on error. */
 739                 num_locks = relock_hash_to_zero(tdb, start, F_RDLCK);
 740                 if (num_locks == TDB_OFF_ERR)
 741                         return tdb_null;
 742
 743                 for (i = start; i < start + num_locks; i++) {
 744                         off = entry_matches(tdb, i, h, &key, &rec);
 745                         /* Empty entry or we found it? */
 746                         if (off == 0 || off != TDB_OFF_ERR)
 747                                 break;
 748                 }
 749                 if (i == start + num_locks)
 750                         off = 0;
 751         }
 752
 753         if (!off) {
 754                 unlock_lists(tdb, start, num_locks, F_RDLCK);
 755                 tdb->ecode = TDB_ERR_NOEXIST;
 756                 return tdb_null;
 757         }
 758
 759         ret.dsize = rec_data_length(&rec);
 760         ret.dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
 761                                   ret.dsize);
 762         unlock_lists(tdb, start, num_locks, F_RDLCK);
 763         return ret;
 764 }
 765
 766 static int hash_add(struct tdb_context *tdb, uint64_t h, tdb_off_t off)
 767 {
 768         tdb_off_t i, hoff, len, num;
 769
 770         /* Look for next space. */
 771         i = (h & ((1ULL << tdb->header.v.hash_bits) - 1));
 772         len = (1ULL << tdb->header.v.hash_bits) - i;
 773         num = tdb_find_zero_off(tdb, hash_off(tdb, i), len);
 774
 775         if (unlikely(num == len)) {
 776                 /* We wrapped.  Look through start of hash table. */
 777                 hoff = hash_off(tdb, 0);
 778                 len = (1ULL << tdb->header.v.hash_bits);
 779                 num = tdb_find_zero_off(tdb, hoff, len);
 780                 if (i == len) {
 781                         tdb->ecode = TDB_ERR_CORRUPT;
 782                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 783                                  "hash_add: full hash table!\n");
 784                         return -1;
 785                 }
 786         }
 787         /* FIXME: Encode extra hash bits! */
 788         return tdb_write_off(tdb, hash_off(tdb, i + num), off);
 789 }
 790
 791 int tdb_delete(struct tdb_context *tdb, struct tdb_data key)
 792 {
 793         tdb_off_t i, old_bucket, off, start, num_locks = 1;
 794         struct tdb_used_record rec;
 795         uint64_t h;
 796
 797         h = tdb_hash(tdb, key.dptr, key.dsize);
 798
 799         /* FIXME: can we avoid locks for some fast paths? */
 800         start = tdb_lock_list(tdb, h, F_WRLCK, TDB_LOCK_WAIT);
 801         if (start == TDB_OFF_ERR)
 802                 return -1;
 803
 804         /* Fast path. */
 805         old_bucket = start;
 806         off = entry_matches(tdb, start, h, &key, &rec);
 807         if (off && off != TDB_OFF_ERR) {
 808                 /* We can only really fastpath delete if next bucket
 809                  * is 0.  Note that we haven't locked it, but our lock
 810                  * on this bucket stops anyone overflowing into it
 811                  * while we look. */
 812                 if (tdb_read_off(tdb, hash_off(tdb, h+1)) == 0)
 813                         goto delete;
 814                 /* Slow path. */
 815                 off = TDB_OFF_ERR;
 816         }
 817
 818         if (unlikely(off == TDB_OFF_ERR)) {
 819                 /* Slow path, need to grab more locks and search. */
 820                 tdb_off_t i;
 821
 822                 /* Warning: this may drop the lock!  Does that on error. */
 823                 num_locks = relock_hash_to_zero(tdb, start, F_WRLCK);
 824                 if (num_locks == TDB_OFF_ERR)
 825                         return -1;
 826
 827                 for (i = start; i < start + num_locks; i++) {
 828                         off = entry_matches(tdb, i, h, &key, &rec);
 829                         /* Empty entry or we found it? */
 830                         if (off == 0 || off != TDB_OFF_ERR) {
 831                                 old_bucket = i;
 832                                 break;
 833                         }
 834                 }
 835                 if (i == start + num_locks)
 836                         off = 0;
 837         }
 838
 839         if (!off) {
 840                 unlock_lists(tdb, start, num_locks, F_WRLCK);
 841                 tdb->ecode = TDB_ERR_NOEXIST;
 842                 return -1;
 843         }
 844
 845 delete:
 846         /* This actually unlinks it. */
 847         if (tdb_write_off(tdb, hash_off(tdb, old_bucket), 0) == -1)
 848                 goto unlock_err;
 849
 850         /* Rehash anything following. */
 851         for (i = hash_off(tdb, old_bucket+1);
 852              i != hash_off(tdb, h + num_locks);
 853              i += sizeof(tdb_off_t)) {
 854                 tdb_off_t off2;
 855                 uint64_t h2;
 856
 857                 off2 = tdb_read_off(tdb, i);
 858                 if (unlikely(off2 == TDB_OFF_ERR))
 859                         goto unlock_err;
 860
 861                 /* Maybe use a bit to indicate it is in ideal place? */
 862                 h2 = hash_record(tdb, off2);
 863                 /* Is it happy where it is? */
 864                 if (hash_off(tdb, h2) == i)
 865                         continue;
 866
 867                 /* Remove it. */
 868                 if (tdb_write_off(tdb, i, 0) == -1)
 869                         goto unlock_err;
 870
 871                 /* Rehash it. */
 872                 if (hash_add(tdb, h2, off2) == -1)
 873                         goto unlock_err;
 874         }
 875
 876         /* Free the deleted entry. */
 877         if (add_free_record(tdb, off,
 878                             sizeof(struct tdb_used_record)
 879                             + rec_key_length(&rec)
 880                             + rec_data_length(&rec)
 881                             + rec_extra_padding(&rec)) != 0)
 882                 goto unlock_err;
 883
 884         unlock_lists(tdb, start, num_locks, F_WRLCK);
 885         return 0;
 886
 887 unlock_err:
 888         unlock_lists(tdb, start, num_locks, F_WRLCK);
 889         return -1;
 890 }
 891
 892 int tdb_close(struct tdb_context *tdb)
 893 {
 894         struct tdb_context **i;
 895         int ret = 0;
 896
 897         /* FIXME:
 898         if (tdb->transaction) {
 899                 tdb_transaction_cancel(tdb);
 900         }
 901         */
 902         tdb_trace(tdb, "tdb_close");
 903
 904         if (tdb->map_ptr) {
 905                 if (tdb->flags & TDB_INTERNAL)
 906                         free(tdb->map_ptr);
 907                 else
 908                         tdb_munmap(tdb);
 909         }
 910         free((char *)tdb->name);
 911         if (tdb->fd != -1) {
 912                 ret = close(tdb->fd);
 913                 tdb->fd = -1;
 914         }
 915         free(tdb->lockrecs);
 916
 917         /* Remove from contexts list */
 918         for (i = &tdbs; *i; i = &(*i)->next) {
 919                 if (*i == tdb) {
 920                         *i = tdb->next;
 921                         break;
 922                 }
 923         }
 924
 925 #ifdef TDB_TRACE
 926         close(tdb->tracefd);
 927 #endif
 928         free(tdb);
 929
 930         return ret;
 931 }
 932
 933 enum TDB_ERROR tdb_error(struct tdb_context *tdb)
 934 {
 935         return tdb->ecode;
 936 }