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_db_head {
 128         struct tdb_header hdr;
 129         struct free_zone_header zhdr;
 130         tdb_off_t free[BUCKETS_FOR_ZONE(INITIAL_ZONE_BITS) + 1];
 131         struct tdb_used_record hrec;
 132         tdb_off_t hash[1ULL << INITIAL_HASH_BITS];
 133         struct tdb_free_record frec;
 134 };
 135
 136 struct new_database {
 137         struct new_db_head h;
 138         /* Rest up to 1 << INITIAL_ZONE_BITS is empty. */
 139         char space[(1 << INITIAL_ZONE_BITS)
 140                    - (sizeof(struct new_db_head) - sizeof(struct tdb_header))];
 141         uint8_t tailer;
 142         /* Don't count final padding! */
 143 };
 144
 145 /* initialise a new database */
 146 static int tdb_new_database(struct tdb_context *tdb)
 147 {
 148         /* We make it up in memory, then write it out if not internal */
 149         struct new_database newdb;
 150         unsigned int bucket, magic_off, dbsize;
 151
 152         /* Don't want any extra padding! */
 153         dbsize = offsetof(struct new_database, tailer) + sizeof(newdb.tailer);
 154
 155         /* Fill in the header */
 156         newdb.h.hdr.version = TDB_VERSION;
 157         newdb.h.hdr.hash_seed = random_number(tdb);
 158         newdb.h.hdr.hash_test = TDB_HASH_MAGIC;
 159         newdb.h.hdr.hash_test = tdb->khash(&newdb.h.hdr.hash_test,
 160                                            sizeof(newdb.h.hdr.hash_test),
 161                                            newdb.h.hdr.hash_seed,
 162                                            tdb->hash_priv);
 163         memset(newdb.h.hdr.reserved, 0, sizeof(newdb.h.hdr.reserved));
 164         newdb.h.hdr.v.generation = 0;
 165         /* Initial hashes are empty. */
 166         newdb.h.hdr.v.hash_bits = INITIAL_HASH_BITS;
 167         newdb.h.hdr.v.hash_off = offsetof(struct new_database, h.hash);
 168         set_header(tdb, &newdb.h.hrec, 0,
 169                    sizeof(newdb.h.hash), sizeof(newdb.h.hash), 0,
 170                    INITIAL_ZONE_BITS);
 171         memset(newdb.h.hash, 0, sizeof(newdb.h.hash));
 172
 173         /* Create the single free entry. */
 174         newdb.h.frec.magic_and_meta = TDB_FREE_MAGIC | INITIAL_ZONE_BITS;
 175         newdb.h.frec.data_len = (sizeof(newdb.h.frec)
 176                                  - sizeof(struct tdb_used_record)
 177                                  + sizeof(newdb.space));
 178
 179         /* Free is mostly empty... */
 180         newdb.h.zhdr.zone_bits = INITIAL_ZONE_BITS;
 181         memset(newdb.h.free, 0, sizeof(newdb.h.free));
 182
 183         /* ... except for this one bucket. */
 184         bucket = size_to_bucket(INITIAL_ZONE_BITS, newdb.h.frec.data_len);
 185         newdb.h.free[bucket] = offsetof(struct new_database, h.frec);
 186         newdb.h.frec.next = newdb.h.frec.prev = 0;
 187
 188         /* Tailer contains maximum number of free_zone bits. */
 189         newdb.tailer = INITIAL_ZONE_BITS;
 190
 191         /* Magic food */
 192         memset(newdb.h.hdr.magic_food, 0, sizeof(newdb.h.hdr.magic_food));
 193         strcpy(newdb.h.hdr.magic_food, TDB_MAGIC_FOOD);
 194
 195         /* This creates an endian-converted database, as if read from disk */
 196         magic_off = offsetof(struct tdb_header, magic_food);
 197         tdb_convert(tdb,
 198                     (char *)&newdb.h.hdr + magic_off,
 199                     dbsize - 1 - magic_off);
 200
 201         tdb->header = newdb.h.hdr;
 202
 203         if (tdb->flags & TDB_INTERNAL) {
 204                 tdb->map_size = dbsize;
 205                 tdb->map_ptr = malloc(tdb->map_size);
 206                 if (!tdb->map_ptr) {
 207                         tdb->ecode = TDB_ERR_OOM;
 208                         return -1;
 209                 }
 210                 memcpy(tdb->map_ptr, &newdb, tdb->map_size);
 211                 return 0;
 212         }
 213         if (lseek(tdb->fd, 0, SEEK_SET) == -1)
 214                 return -1;
 215
 216         if (ftruncate(tdb->fd, 0) == -1)
 217                 return -1;
 218
 219         if (!tdb_pwrite_all(tdb->fd, &newdb, dbsize, 0)) {
 220                 tdb->ecode = TDB_ERR_IO;
 221                 return -1;
 222         }
 223         return 0;
 224 }
 225
 226 struct tdb_context *tdb_open(const char *name, int tdb_flags,
 227                              int open_flags, mode_t mode,
 228                              union tdb_attribute *attr)
 229 {
 230         struct tdb_context *tdb;
 231         struct stat st;
 232         int save_errno;
 233         uint64_t hash_test;
 234         unsigned v;
 235
 236         tdb = malloc(sizeof(*tdb));
 237         if (!tdb) {
 238                 /* Can't log this */
 239                 errno = ENOMEM;
 240                 goto fail;
 241         }
 242         tdb->name = NULL;
 243         tdb->map_ptr = NULL;
 244         tdb->fd = -1;
 245         tdb->map_size = sizeof(struct tdb_header);
 246         tdb->ecode = TDB_SUCCESS;
 247         /* header will be read in below. */
 248         tdb->header_uptodate = false;
 249         tdb->flags = tdb_flags;
 250         tdb->log = null_log_fn;
 251         tdb->log_priv = NULL;
 252         tdb->khash = jenkins_hash;
 253         tdb->hash_priv = NULL;
 254         tdb->transaction = NULL;
 255         /* last_zone will be set below. */
 256         tdb_io_init(tdb);
 257         tdb_lock_init(tdb);
 258
 259         while (attr) {
 260                 switch (attr->base.attr) {
 261                 case TDB_ATTRIBUTE_LOG:
 262                         tdb->log = attr->log.log_fn;
 263                         tdb->log_priv = attr->log.log_private;
 264                         break;
 265                 case TDB_ATTRIBUTE_HASH:
 266                         tdb->khash = attr->hash.hash_fn;
 267                         tdb->hash_priv = attr->hash.hash_private;
 268                         break;
 269                 default:
 270                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 271                                  "tdb_open: unknown attribute type %u\n",
 272                                  attr->base.attr);
 273                         errno = EINVAL;
 274                         goto fail;
 275                 }
 276                 attr = attr->base.next;
 277         }
 278
 279         if ((open_flags & O_ACCMODE) == O_WRONLY) {
 280                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 281                          "tdb_open: can't open tdb %s write-only\n", name);
 282                 errno = EINVAL;
 283                 goto fail;
 284         }
 285
 286         if ((open_flags & O_ACCMODE) == O_RDONLY) {
 287                 tdb->read_only = true;
 288                 /* read only databases don't do locking */
 289                 tdb->flags |= TDB_NOLOCK;
 290         } else
 291                 tdb->read_only = false;
 292
 293         /* internal databases don't need any of the rest. */
 294         if (tdb->flags & TDB_INTERNAL) {
 295                 tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
 296                 if (tdb_new_database(tdb) != 0) {
 297                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 298                                  "tdb_open: tdb_new_database failed!");
 299                         goto fail;
 300                 }
 301                 TEST_IT(tdb->flags & TDB_CONVERT);
 302                 tdb_convert(tdb, &tdb->header, sizeof(tdb->header));
 303                 tdb_zone_init(tdb);
 304                 return tdb;
 305         }
 306
 307         if ((tdb->fd = open(name, open_flags, mode)) == -1) {
 308                 tdb->log(tdb, TDB_DEBUG_WARNING, tdb->log_priv,
 309                          "tdb_open: could not open file %s: %s\n",
 310                          name, strerror(errno));
 311                 goto fail;      /* errno set by open(2) */
 312         }
 313
 314         /* on exec, don't inherit the fd */
 315         v = fcntl(tdb->fd, F_GETFD, 0);
 316         fcntl(tdb->fd, F_SETFD, v | FD_CLOEXEC);
 317
 318         /* ensure there is only one process initialising at once */
 319         if (tdb_lock_open(tdb) == -1) {
 320                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 321                          "tdb_open: failed to get open lock on %s: %s\n",
 322                          name, strerror(errno));
 323                 goto fail;      /* errno set by tdb_brlock */
 324         }
 325
 326         if (!tdb_pread_all(tdb->fd, &tdb->header, sizeof(tdb->header), 0)
 327             || strcmp(tdb->header.magic_food, TDB_MAGIC_FOOD) != 0) {
 328                 if (!(open_flags & O_CREAT) || tdb_new_database(tdb) == -1) {
 329                         if (errno == 0) {
 330                                 errno = EIO; /* ie bad format or something */
 331                         }
 332                         goto fail;
 333                 }
 334         } else if (tdb->header.version != TDB_VERSION) {
 335                 if (tdb->header.version == bswap_64(TDB_VERSION))
 336                         tdb->flags |= TDB_CONVERT;
 337                 else {
 338                         /* wrong version */
 339                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 340                                  "tdb_open: %s is unknown version 0x%llx\n",
 341                                  name, (long long)tdb->header.version);
 342                         errno = EIO;
 343                         goto fail;
 344                 }
 345         }
 346
 347         tdb_convert(tdb, &tdb->header, sizeof(tdb->header));
 348         hash_test = TDB_HASH_MAGIC;
 349         hash_test = tdb->khash(&hash_test, sizeof(hash_test),
 350                                tdb->header.hash_seed, tdb->hash_priv);
 351         if (tdb->header.hash_test != hash_test) {
 352                 /* wrong hash variant */
 353                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 354                          "tdb_open: %s uses a different hash function\n",
 355                          name);
 356                 errno = EIO;
 357                 goto fail;
 358         }
 359
 360         if (fstat(tdb->fd, &st) == -1)
 361                 goto fail;
 362
 363         /* Is it already in the open list?  If so, fail. */
 364         if (tdb_already_open(st.st_dev, st.st_ino)) {
 365                 /* FIXME */
 366                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 367                          "tdb_open: %s (%d,%d) is already open in this process\n",
 368                          name, (int)st.st_dev, (int)st.st_ino);
 369                 errno = EBUSY;
 370                 goto fail;
 371         }
 372
 373         tdb->name = strdup(name);
 374         if (!tdb->name) {
 375                 errno = ENOMEM;
 376                 goto fail;
 377         }
 378
 379         tdb->device = st.st_dev;
 380         tdb->inode = st.st_ino;
 381         tdb_unlock_open(tdb);
 382
 383         /* This make sure we have current map_size and mmap. */
 384         tdb->methods->oob(tdb, tdb->map_size + 1, true);
 385
 386         /* Now we can pick a random free zone to start from. */
 387         if (tdb_zone_init(tdb) == -1)
 388                 goto fail;
 389
 390         tdb->next = tdbs;
 391         tdbs = tdb;
 392         return tdb;
 393
 394  fail:
 395         save_errno = errno;
 396
 397         if (!tdb)
 398                 return NULL;
 399
 400 #ifdef TDB_TRACE
 401         close(tdb->tracefd);
 402 #endif
 403         if (tdb->map_ptr) {
 404                 if (tdb->flags & TDB_INTERNAL) {
 405                         free(tdb->map_ptr);
 406                 } else
 407                         tdb_munmap(tdb);
 408         }
 409         free((char *)tdb->name);
 410         if (tdb->fd != -1)
 411                 if (close(tdb->fd) != 0)
 412                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 413                                  "tdb_open: failed to close tdb->fd"
 414                                  " on error!\n");
 415         free(tdb);
 416         errno = save_errno;
 417         return NULL;
 418 }
 419
 420 tdb_off_t hash_off(struct tdb_context *tdb, uint64_t list)
 421 {
 422         return tdb->header.v.hash_off
 423                 + ((list & ((1ULL << tdb->header.v.hash_bits) - 1))
 424                    * sizeof(tdb_off_t));
 425 }
 426
 427 /* Returns 0 if the entry is a zero (definitely not a match).
 428  * Returns a valid entry offset if it's a match.  Fills in rec.
 429  * Otherwise returns TDB_OFF_ERR: keep searching. */
 430 static tdb_off_t entry_matches(struct tdb_context *tdb,
 431                                uint64_t list,
 432                                uint64_t hash,
 433                                const struct tdb_data *key,
 434                                struct tdb_used_record *rec)
 435 {
 436         tdb_off_t off;
 437         uint64_t keylen;
 438         const unsigned char *rkey;
 439
 440         list &= ((1ULL << tdb->header.v.hash_bits) - 1);
 441
 442         off = tdb_read_off(tdb, tdb->header.v.hash_off
 443                            + list * sizeof(tdb_off_t));
 444         if (off == 0 || off == TDB_OFF_ERR)
 445                 return off;
 446
 447 #if 0 /* FIXME: Check other bits. */
 448         unsigned int bits, bitmask, hoffextra;
 449         /* Bottom three bits show how many extra hash bits. */
 450         bits = (off & ((1 << TDB_EXTRA_HASHBITS_NUM) - 1)) + 1;
 451         bitmask = (1 << bits)-1;
 452         hoffextra = ((off >> TDB_EXTRA_HASHBITS_NUM) & bitmask);
 453         uint64_t hextra = hash >> tdb->header.v.hash_bits;
 454         if ((hextra & bitmask) != hoffextra)
 455                 return TDB_OFF_ERR;
 456         off &= ~...;
 457 #endif
 458
 459         if (tdb_read_convert(tdb, off, rec, sizeof(*rec)) == -1)
 460                 return TDB_OFF_ERR;
 461
 462         /* FIXME: check extra bits in header! */
 463         keylen = rec_key_length(rec);
 464         if (keylen != key->dsize)
 465                 return TDB_OFF_ERR;
 466
 467         rkey = tdb_access_read(tdb, off + sizeof(*rec), keylen, false);
 468         if (!rkey)
 469                 return TDB_OFF_ERR;
 470         if (memcmp(rkey, key->dptr, keylen) != 0)
 471                 off = TDB_OFF_ERR;
 472         tdb_access_release(tdb, rkey);
 473         return off;
 474 }
 475
 476 /* FIXME: Optimize? */
 477 static void unlock_lists(struct tdb_context *tdb,
 478                          tdb_off_t list, tdb_len_t num,
 479                          int ltype)
 480 {
 481         tdb_off_t i;
 482
 483         for (i = list; i < list + num; i++)
 484                 tdb_unlock_list(tdb, i, ltype);
 485 }
 486
 487 /* FIXME: Optimize? */
 488 static int lock_lists(struct tdb_context *tdb,
 489                       tdb_off_t list, tdb_len_t num,
 490                       int ltype)
 491 {
 492         tdb_off_t i;
 493
 494         for (i = list; i < list + num; i++) {
 495                 if (tdb_lock_list(tdb, i, ltype, TDB_LOCK_WAIT)
 496                     == TDB_OFF_ERR) {
 497                         unlock_lists(tdb, list, i - list, ltype);
 498                         return -1;
 499                 }
 500         }
 501         return 0;
 502 }
 503
 504 /* We lock hashes up to the next empty offset.  We already hold the
 505  * lock on the start bucket, but we may need to release and re-grab
 506  * it.  If we fail, we hold no locks at all! */
 507 static tdb_len_t relock_hash_to_zero(struct tdb_context *tdb,
 508                                      tdb_off_t start, int ltype)
 509 {
 510         tdb_len_t num, len;
 511
 512 again:
 513         num = 1ULL << tdb->header.v.hash_bits;
 514         len = tdb_find_zero_off(tdb, hash_off(tdb, start), num - start);
 515         if (unlikely(len == num - start)) {
 516                 /* We hit the end of the hash range.  Drop lock: we have
 517                    to lock start of hash first. */
 518                 tdb_len_t pre_locks;
 519
 520                 tdb_unlock_list(tdb, start, ltype);
 521
 522                 /* Grab something, so header is stable. */
 523                 if (tdb_lock_list(tdb, 0, ltype, TDB_LOCK_WAIT))
 524                         return TDB_OFF_ERR;
 525                 pre_locks = tdb_find_zero_off(tdb, hash_off(tdb, 0), num);
 526                 /* We want to lock the zero entry as well. */
 527                 pre_locks++;
 528                 if (lock_lists(tdb, 1, pre_locks - 1, ltype) == -1) {
 529                         tdb_unlock_list(tdb, 0, ltype);
 530                         return TDB_OFF_ERR;
 531                 }
 532
 533                 /* Now lock later ones. */
 534                 if (unlikely(lock_lists(tdb, start, len, ltype) == -1)) {
 535                         unlock_lists(tdb, 0, pre_locks, ltype);
 536                         return TDB_OFF_ERR;
 537                 }
 538                 len += pre_locks;
 539         } else {
 540                 /* We want to lock the zero entry as well. */
 541                 len++;
 542                 /* But we already have lock on start. */
 543                 if (unlikely(lock_lists(tdb, start+1, len-1, ltype) == -1)) {
 544                         tdb_unlock_list(tdb, start, ltype);
 545                         return TDB_OFF_ERR;
 546                 }
 547         }
 548
 549         /* Now, did we lose the race, and it's not zero any more? */
 550         if (unlikely(tdb_read_off(tdb, hash_off(tdb, start + len - 1)) != 0)) {
 551                 /* Leave the start locked, as expected. */
 552                 unlock_lists(tdb, start + 1, len - 1, ltype);
 553                 goto again;
 554         }
 555
 556         return len;
 557 }
 558
 559 /* FIXME: modify, don't rewrite! */
 560 static int update_rec_hdr(struct tdb_context *tdb,
 561                           tdb_off_t off,
 562                           tdb_len_t keylen,
 563                           tdb_len_t datalen,
 564                           struct tdb_used_record *rec,
 565                           uint64_t h)
 566 {
 567         uint64_t dataroom = rec_data_length(rec) + rec_extra_padding(rec);
 568
 569         if (set_header(tdb, rec, keylen, datalen, keylen + dataroom, h,
 570                        rec_zone_bits(rec)))
 571                 return -1;
 572
 573         return tdb_write_convert(tdb, off, rec, sizeof(*rec));
 574 }
 575
 576 static int hash_add(struct tdb_context *tdb,
 577                     uint64_t hash, tdb_off_t off)
 578 {
 579         tdb_off_t i, hoff, len, num;
 580
 581         /* Look for next space. */
 582         i = (hash & ((1ULL << tdb->header.v.hash_bits) - 1));
 583         len = (1ULL << tdb->header.v.hash_bits) - i;
 584         num = tdb_find_zero_off(tdb, hash_off(tdb, i), len);
 585
 586         if (unlikely(num == len)) {
 587                 /* We wrapped.  Look through start of hash table. */
 588                 i = 0;
 589                 hoff = hash_off(tdb, 0);
 590                 len = (1ULL << tdb->header.v.hash_bits);
 591                 num = tdb_find_zero_off(tdb, hoff, len);
 592                 if (num == len) {
 593                         tdb->ecode = TDB_ERR_CORRUPT;
 594                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 595                                  "hash_add: full hash table!\n");
 596                         return -1;
 597                 }
 598         }
 599         if (tdb_read_off(tdb, hash_off(tdb, i + num)) != 0) {
 600                 tdb->ecode = TDB_ERR_CORRUPT;
 601                 tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 602                          "hash_add: overwriting hash table?\n");
 603                 return -1;
 604         }
 605
 606         /* FIXME: Encode extra hash bits! */
 607         return tdb_write_off(tdb, hash_off(tdb, i + num), off);
 608 }
 609
 610 /* If we fail, others will try after us. */
 611 static void enlarge_hash(struct tdb_context *tdb)
 612 {
 613         tdb_off_t newoff, oldoff, i;
 614         tdb_len_t hlen;
 615         uint64_t num = 1ULL << tdb->header.v.hash_bits;
 616         struct tdb_used_record pad, *r;
 617         unsigned int records = 0;
 618
 619         /* FIXME: We should do this without holding locks throughout. */
 620         if (tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false) == -1)
 621                 return;
 622
 623         /* Someone else enlarged for us?  Nothing to do. */
 624         if ((1ULL << tdb->header.v.hash_bits) != num)
 625                 goto unlock;
 626
 627 again:
 628         /* Allocate our new array. */
 629         hlen = num * sizeof(tdb_off_t) * 2;
 630         newoff = alloc(tdb, 0, hlen, 0, false);
 631         if (unlikely(newoff == TDB_OFF_ERR))
 632                 goto unlock;
 633         if (unlikely(newoff == 0)) {
 634                 if (tdb_expand(tdb, 0, hlen, false) == -1)
 635                         goto unlock;
 636                 goto again;
 637         }
 638         /* Step over record header! */
 639         newoff += sizeof(struct tdb_used_record);
 640
 641         /* Starts all zero. */
 642         if (zero_out(tdb, newoff, hlen) == -1)
 643                 goto unlock;
 644
 645         /* Update header now so we can use normal routines. */
 646         oldoff = tdb->header.v.hash_off;
 647
 648         tdb->header.v.hash_bits++;
 649         tdb->header.v.hash_off = newoff;
 650
 651         /* FIXME: If the space before is empty, we know this is in its ideal
 652          * location.  Or steal a bit from the pointer to avoid rehash. */
 653         for (i = 0; i < num; i++) {
 654                 tdb_off_t off;
 655                 off = tdb_read_off(tdb, oldoff + i * sizeof(tdb_off_t));
 656                 if (unlikely(off == TDB_OFF_ERR))
 657                         goto oldheader;
 658                 if (off && hash_add(tdb, hash_record(tdb, off), off) == -1)
 659                         goto oldheader;
 660                 if (off)
 661                         records++;
 662         }
 663
 664         tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
 665                  "enlarge_hash: moved %u records from %llu buckets.\n",
 666                  records, (long long)num);
 667
 668         /* Free up old hash. */
 669         r = tdb_get(tdb, oldoff - sizeof(*r), &pad, sizeof(*r));
 670         if (!r)
 671                 goto oldheader;
 672         add_free_record(tdb, rec_zone_bits(r), oldoff - sizeof(*r),
 673                         sizeof(*r)+rec_data_length(r)+rec_extra_padding(r));
 674
 675         /* Now we write the modified header. */
 676         write_header(tdb);
 677 unlock:
 678         tdb_allrecord_unlock(tdb, F_WRLCK);
 679         return;
 680
 681 oldheader:
 682         tdb->header.v.hash_bits--;
 683         tdb->header.v.hash_off = oldoff;
 684         goto unlock;
 685 }
 686
 687
 688 /* This is the slow version of the routine which searches the
 689  * hashtable for an entry.
 690  * We lock every hash bucket up to and including the next zero one.
 691  */
 692 static tdb_off_t find_and_lock_slow(struct tdb_context *tdb,
 693                                     struct tdb_data key,
 694                                     uint64_t h,
 695                                     int ltype,
 696                                     tdb_off_t *start_lock,
 697                                     tdb_len_t *num_locks,
 698                                     tdb_off_t *bucket,
 699                                     struct tdb_used_record *rec)
 700 {
 701         /* Warning: this may drop the lock on *bucket! */
 702         *num_locks = relock_hash_to_zero(tdb, *start_lock, ltype);
 703         if (*num_locks == TDB_OFF_ERR)
 704                 return TDB_OFF_ERR;
 705
 706         for (*bucket = *start_lock;
 707              *bucket < *start_lock + *num_locks;
 708              (*bucket)++) {
 709                 tdb_off_t off = entry_matches(tdb, *bucket, h, &key, rec);
 710                 /* Empty entry or we found it? */
 711                 if (off == 0 || off != TDB_OFF_ERR)
 712                         return off;
 713         }
 714
 715         /* We didn't find a zero entry?  Something went badly wrong... */
 716         unlock_lists(tdb, *start_lock, *start_lock + *num_locks, ltype);
 717         tdb->ecode = TDB_ERR_CORRUPT;
 718         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 719                  "find_and_lock: expected to find an empty hash bucket!\n");
 720         return TDB_OFF_ERR;
 721 }
 722
 723 /* This is the core routine which searches the hashtable for an entry.
 724  * On error, no locks are held and TDB_OFF_ERR is returned.
 725  * Otherwise, *num_locks locks of type ltype from *start_lock are held.
 726  * The bucket where the entry is (or would be) is in *bucket.
 727  * If not found, the return value is 0.
 728  * If found, the return value is the offset, and *rec is the record. */
 729 static tdb_off_t find_and_lock(struct tdb_context *tdb,
 730                                struct tdb_data key,
 731                                uint64_t h,
 732                                int ltype,
 733                                tdb_off_t *start_lock,
 734                                tdb_len_t *num_locks,
 735                                tdb_off_t *bucket,
 736                                struct tdb_used_record *rec)
 737 {
 738         tdb_off_t off;
 739
 740         /* FIXME: can we avoid locks for some fast paths? */
 741         *start_lock = tdb_lock_list(tdb, h, ltype, TDB_LOCK_WAIT);
 742         if (*start_lock == TDB_OFF_ERR)
 743                 return TDB_OFF_ERR;
 744
 745         /* Fast path. */
 746         off = entry_matches(tdb, *start_lock, h, &key, rec);
 747         if (likely(off != TDB_OFF_ERR)) {
 748                 *bucket = *start_lock;
 749                 *num_locks = 1;
 750                 return off;
 751         }
 752
 753         /* Slow path, need to grab more locks and search. */
 754         return find_and_lock_slow(tdb, key, h, ltype, start_lock, num_locks,
 755                                   bucket, rec);
 756 }
 757
 758 /* Returns -1 on error, 0 on OK, 1 on "expand and retry." */
 759 static int replace_data(struct tdb_context *tdb,
 760                         uint64_t h, struct tdb_data key, struct tdb_data dbuf,
 761                         tdb_off_t bucket,
 762                         tdb_off_t old_off, tdb_len_t old_room,
 763                         unsigned old_zone,
 764                         bool growing)
 765 {
 766         tdb_off_t new_off;
 767
 768         /* Allocate a new record. */
 769         new_off = alloc(tdb, key.dsize, dbuf.dsize, h, growing);
 770         if (unlikely(new_off == TDB_OFF_ERR))
 771                 return -1;
 772
 773         if (unlikely(new_off == 0))
 774                 return 1;
 775
 776         /* We didn't like the existing one: remove it. */
 777         if (old_off)
 778                 add_free_record(tdb, old_zone, old_off,
 779                                 sizeof(struct tdb_used_record)
 780                                 + key.dsize + old_room);
 781
 782         /* FIXME: Encode extra hash bits! */
 783         if (tdb_write_off(tdb, hash_off(tdb, bucket), new_off) == -1)
 784                 return -1;
 785
 786         new_off += sizeof(struct tdb_used_record);
 787         if (tdb->methods->write(tdb, new_off, key.dptr, key.dsize) == -1)
 788                 return -1;
 789
 790         new_off += key.dsize;
 791         if (tdb->methods->write(tdb, new_off, dbuf.dptr, dbuf.dsize) == -1)
 792                 return -1;
 793
 794         /* FIXME: tdb_increment_seqnum(tdb); */
 795         return 0;
 796 }
 797
 798 int tdb_store(struct tdb_context *tdb,
 799               struct tdb_data key, struct tdb_data dbuf, int flag)
 800 {
 801         tdb_off_t off, bucket, start, num;
 802         tdb_len_t old_room = 0;
 803         struct tdb_used_record rec;
 804         uint64_t h;
 805         int ret;
 806
 807         h = tdb_hash(tdb, key.dptr, key.dsize);
 808         off = find_and_lock(tdb, key, h, F_WRLCK, &start, &num, &bucket, &rec);
 809         if (unlikely(off == TDB_OFF_ERR))
 810                 return -1;
 811
 812         /* Now we have lock on this hash bucket. */
 813         if (flag == TDB_INSERT) {
 814                 if (off) {
 815                         tdb->ecode = TDB_ERR_EXISTS;
 816                         goto fail;
 817                 }
 818         } else {
 819                 if (off) {
 820                         old_room = rec_data_length(&rec)
 821                                 + rec_extra_padding(&rec);
 822                         if (old_room >= dbuf.dsize) {
 823                                 /* Can modify in-place.  Easy! */
 824                                 if (update_rec_hdr(tdb, off,
 825                                                    key.dsize, dbuf.dsize,
 826                                                    &rec, h))
 827                                         goto fail;
 828                                 if (tdb->methods->write(tdb, off + sizeof(rec)
 829                                                         + key.dsize,
 830                                                         dbuf.dptr, dbuf.dsize))
 831                                         goto fail;
 832                                 unlock_lists(tdb, start, num, F_WRLCK);
 833                                 return 0;
 834                         }
 835                         /* FIXME: See if right record is free? */
 836                 } else {
 837                         if (flag == TDB_MODIFY) {
 838                                 /* if the record doesn't exist and we
 839                                    are in TDB_MODIFY mode then we should fail
 840                                    the store */
 841                                 tdb->ecode = TDB_ERR_NOEXIST;
 842                                 goto fail;
 843                         }
 844                 }
 845         }
 846
 847         /* If we didn't use the old record, this implies we're growing. */
 848         ret = replace_data(tdb, h, key, dbuf, bucket, off, old_room,
 849                            rec_zone_bits(&rec), off != 0);
 850         unlock_lists(tdb, start, num, F_WRLCK);
 851
 852         if (unlikely(ret == 1)) {
 853                 /* Expand, then try again... */
 854                 if (tdb_expand(tdb, key.dsize, dbuf.dsize, off != 0) == -1)
 855                         return -1;
 856                 return tdb_store(tdb, key, dbuf, flag);
 857         }
 858
 859         /* FIXME: by simple simulation, this approximated 60% full.
 860          * Check in real case! */
 861         if (unlikely(num > 4 * tdb->header.v.hash_bits - 30))
 862                 enlarge_hash(tdb);
 863
 864         return ret;
 865
 866 fail:
 867         unlock_lists(tdb, start, num, F_WRLCK);
 868         return -1;
 869 }
 870
 871 int tdb_append(struct tdb_context *tdb,
 872                struct tdb_data key, struct tdb_data dbuf)
 873 {
 874         tdb_off_t off, bucket, start, num;
 875         struct tdb_used_record rec;
 876         tdb_len_t old_room = 0, old_dlen;
 877         uint64_t h;
 878         unsigned char *newdata;
 879         struct tdb_data new_dbuf;
 880         int ret;
 881
 882         h = tdb_hash(tdb, key.dptr, key.dsize);
 883         off = find_and_lock(tdb, key, h, F_WRLCK, &start, &num, &bucket, &rec);
 884         if (unlikely(off == TDB_OFF_ERR))
 885                 return -1;
 886
 887         if (off) {
 888                 old_dlen = rec_data_length(&rec);
 889                 old_room = old_dlen + rec_extra_padding(&rec);
 890
 891                 /* Fast path: can append in place. */
 892                 if (rec_extra_padding(&rec) >= dbuf.dsize) {
 893                         if (update_rec_hdr(tdb, off, key.dsize,
 894                                            old_dlen + dbuf.dsize, &rec, h))
 895                                 goto fail;
 896
 897                         off += sizeof(rec) + key.dsize + old_dlen;
 898                         if (tdb->methods->write(tdb, off, dbuf.dptr,
 899                                                 dbuf.dsize) == -1)
 900                                 goto fail;
 901
 902                         /* FIXME: tdb_increment_seqnum(tdb); */
 903                         unlock_lists(tdb, start, num, F_WRLCK);
 904                         return 0;
 905                 }
 906                 /* FIXME: Check right record free? */
 907
 908                 /* Slow path. */
 909                 newdata = malloc(key.dsize + old_dlen + dbuf.dsize);
 910                 if (!newdata) {
 911                         tdb->ecode = TDB_ERR_OOM;
 912                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 913                                  "tdb_append: cannot allocate %llu bytes!\n",
 914                                  (long long)key.dsize + old_dlen + dbuf.dsize);
 915                         goto fail;
 916                 }
 917                 if (tdb->methods->read(tdb, off + sizeof(rec) + key.dsize,
 918                                        newdata, old_dlen) != 0) {
 919                         free(newdata);
 920                         goto fail;
 921                 }
 922                 memcpy(newdata + old_dlen, dbuf.dptr, dbuf.dsize);
 923                 new_dbuf.dptr = newdata;
 924                 new_dbuf.dsize = old_dlen + dbuf.dsize;
 925         } else {
 926                 newdata = NULL;
 927                 new_dbuf = dbuf;
 928         }
 929
 930         /* If they're using tdb_append(), it implies they're growing record. */
 931         ret = replace_data(tdb, h, key, new_dbuf, bucket, off, old_room,
 932                            rec_zone_bits(&rec), true);
 933         unlock_lists(tdb, start, num, F_WRLCK);
 934         free(newdata);
 935
 936         if (unlikely(ret == 1)) {
 937                 /* Expand, then try again. */
 938                 if (tdb_expand(tdb, key.dsize, dbuf.dsize, true) == -1)
 939                         return -1;
 940                 return tdb_append(tdb, key, dbuf);
 941         }
 942
 943         /* FIXME: by simple simulation, this approximated 60% full.
 944          * Check in real case! */
 945         if (unlikely(num > 4 * tdb->header.v.hash_bits - 30))
 946                 enlarge_hash(tdb);
 947
 948         return ret;
 949
 950 fail:
 951         unlock_lists(tdb, start, num, F_WRLCK);
 952         return -1;
 953 }
 954
 955 struct tdb_data tdb_fetch(struct tdb_context *tdb, struct tdb_data key)
 956 {
 957         tdb_off_t off, start, num, bucket;
 958         struct tdb_used_record rec;
 959         uint64_t h;
 960         struct tdb_data ret;
 961
 962         h = tdb_hash(tdb, key.dptr, key.dsize);
 963         off = find_and_lock(tdb, key, h, F_RDLCK, &start, &num, &bucket, &rec);
 964         if (unlikely(off == TDB_OFF_ERR))
 965                 return tdb_null;
 966
 967         if (!off) {
 968                 tdb->ecode = TDB_ERR_NOEXIST;
 969                 ret = tdb_null;
 970         } else {
 971                 ret.dsize = rec_data_length(&rec);
 972                 ret.dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
 973                                           ret.dsize);
 974         }
 975
 976         unlock_lists(tdb, start, num, F_RDLCK);
 977         return ret;
 978 }
 979
 980 int tdb_delete(struct tdb_context *tdb, struct tdb_data key)
 981 {
 982         tdb_off_t i, bucket, off, start, num;
 983         struct tdb_used_record rec;
 984         uint64_t h;
 985
 986         h = tdb_hash(tdb, key.dptr, key.dsize);
 987         start = tdb_lock_list(tdb, h, F_WRLCK, TDB_LOCK_WAIT);
 988         if (unlikely(start == TDB_OFF_ERR))
 989                 return -1;
 990
 991         /* FIXME: Fastpath: if next is zero, we can delete without lock,
 992          * since this lock protects us. */
 993         off = find_and_lock_slow(tdb, key, h, F_WRLCK,
 994                                  &start, &num, &bucket, &rec);
 995         if (unlikely(off == TDB_OFF_ERR))
 996                 return -1;
 997
 998         if (!off) {
 999                 /* FIXME: We could optimize not found case if it mattered, by
1000                  * reading offset after first lock: if it's zero, goto here. */
1001                 unlock_lists(tdb, start, num, F_WRLCK);
1002                 tdb->ecode = TDB_ERR_NOEXIST;
1003                 return -1;
1004         }
1005         /* Since we found the entry, we must have locked it and a zero. */
1006         assert(num >= 2);
1007
1008         /* This actually unlinks it. */
1009         if (tdb_write_off(tdb, hash_off(tdb, bucket), 0) == -1)
1010                 goto unlock_err;
1011
1012         /* Rehash anything following. */
1013         for (i = bucket+1; i != bucket + num - 1; i++) {
1014                 tdb_off_t hoff, off2;
1015                 uint64_t h2;
1016
1017                 hoff = hash_off(tdb, i);
1018                 off2 = tdb_read_off(tdb, hoff);
1019                 if (unlikely(off2 == TDB_OFF_ERR))
1020                         goto unlock_err;
1021
1022                 /* This can happen if we raced. */
1023                 if (unlikely(off2 == 0))
1024                         break;
1025
1026                 /* Maybe use a bit to indicate it is in ideal place? */
1027                 h2 = hash_record(tdb, off2);
1028                 /* Is it happy where it is? */
1029                 if (hash_off(tdb, h2) == hoff)
1030                         continue;
1031
1032                 /* Remove it. */
1033                 if (tdb_write_off(tdb, hoff, 0) == -1)
1034                         goto unlock_err;
1035
1036                 /* Rehash it. */
1037                 if (hash_add(tdb, h2, off2) == -1)
1038                         goto unlock_err;
1039         }
1040
1041         /* Free the deleted entry. */
1042         if (add_free_record(tdb, rec_zone_bits(&rec), off,
1043                             sizeof(struct tdb_used_record)
1044                             + rec_key_length(&rec)
1045                             + rec_data_length(&rec)
1046                             + rec_extra_padding(&rec)) != 0)
1047                 goto unlock_err;
1048
1049         unlock_lists(tdb, start, num, F_WRLCK);
1050         return 0;
1051
1052 unlock_err:
1053         unlock_lists(tdb, start, num, F_WRLCK);
1054         return -1;
1055 }
1056
1057 int tdb_close(struct tdb_context *tdb)
1058 {
1059         struct tdb_context **i;
1060         int ret = 0;
1061
1062         /* FIXME:
1063         if (tdb->transaction) {
1064                 tdb_transaction_cancel(tdb);
1065         }
1066         */
1067         tdb_trace(tdb, "tdb_close");
1068
1069         if (tdb->map_ptr) {
1070                 if (tdb->flags & TDB_INTERNAL)
1071                         free(tdb->map_ptr);
1072                 else
1073                         tdb_munmap(tdb);
1074         }
1075         free((char *)tdb->name);
1076         if (tdb->fd != -1) {
1077                 ret = close(tdb->fd);
1078                 tdb->fd = -1;
1079         }
1080         free(tdb->lockrecs);
1081
1082         /* Remove from contexts list */
1083         for (i = &tdbs; *i; i = &(*i)->next) {
1084                 if (*i == tdb) {
1085                         *i = tdb->next;
1086                         break;
1087                 }
1088         }
1089
1090 #ifdef TDB_TRACE
1091         close(tdb->tracefd);
1092 #endif
1093         free(tdb);
1094
1095         return ret;
1096 }
1097
1098 enum TDB_ERROR tdb_error(struct tdb_context *tdb)
1099 {
1100         return tdb->ecode;
1101 }