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                 /* Zones don't matter for internal db. */
 272                 tdb->last_zone = 0;
 273                 return tdb;
 274         }
 275
 276         if ((tdb->fd = open(name, open_flags, mode)) == -1) {
 277                 tdb->log(tdb, TDB_DEBUG_WARNING, tdb->log_priv,
 278                          "tdb_open: could not open file %s: %s\n",
 279                          name, strerror(errno));
 280                 goto fail;      /* errno set by open(2) */
 281         }
 282
 283         /* on exec, don't inherit the fd */
 284         v = fcntl(tdb->fd, F_GETFD, 0);
 285         fcntl(tdb->fd, F_SETFD, v | FD_CLOEXEC);
 286
 287         /* ensure there is only one process initialising at once */
 288         if (tdb_lock_open(tdb) == -1) {
 289                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 290                          "tdb_open: failed to get open lock on %s: %s\n",
 291                          name, strerror(errno));
 292                 goto fail;      /* errno set by tdb_brlock */
 293         }
 294
 295         if (!tdb_pread_all(tdb->fd, &tdb->header, sizeof(tdb->header), 0)
 296             || strcmp(tdb->header.magic_food, TDB_MAGIC_FOOD) != 0) {
 297                 if (!(open_flags & O_CREAT) || tdb_new_database(tdb) == -1) {
 298                         if (errno == 0) {
 299                                 errno = EIO; /* ie bad format or something */
 300                         }
 301                         goto fail;
 302                 }
 303         } else if (tdb->header.version != TDB_VERSION) {
 304                 if (tdb->header.version == bswap_64(TDB_VERSION))
 305                         tdb->flags |= TDB_CONVERT;
 306                 else {
 307                         /* wrong version */
 308                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 309                                  "tdb_open: %s is unknown version 0x%llx\n",
 310                                  name, (long long)tdb->header.version);
 311                         errno = EIO;
 312                         goto fail;
 313                 }
 314         }
 315
 316         tdb_convert(tdb, &tdb->header, sizeof(tdb->header));
 317         hash_test = TDB_HASH_MAGIC;
 318         hash_test = tdb->khash(&hash_test, sizeof(hash_test),
 319                                tdb->header.hash_seed, tdb->hash_priv);
 320         if (tdb->header.hash_test != hash_test) {
 321                 /* wrong hash variant */
 322                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 323                          "tdb_open: %s uses a different hash function\n",
 324                          name);
 325                 errno = EIO;
 326                 goto fail;
 327         }
 328
 329         if (fstat(tdb->fd, &st) == -1)
 330                 goto fail;
 331
 332         /* Is it already in the open list?  If so, fail. */
 333         if (tdb_already_open(st.st_dev, st.st_ino)) {
 334                 /* FIXME */
 335                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 336                          "tdb_open: %s (%d,%d) is already open in this process\n",
 337                          name, (int)st.st_dev, (int)st.st_ino);
 338                 errno = EBUSY;
 339                 goto fail;
 340         }
 341
 342         tdb->name = strdup(name);
 343         if (!tdb->name) {
 344                 errno = ENOMEM;
 345                 goto fail;
 346         }
 347
 348         tdb->map_size = st.st_size;
 349         tdb->device = st.st_dev;
 350         tdb->inode = st.st_ino;
 351         tdb_mmap(tdb);
 352         tdb_unlock_open(tdb);
 353         tdb_zone_init(tdb);
 354
 355         tdb->next = tdbs;
 356         tdbs = tdb;
 357         return tdb;
 358
 359  fail:
 360         save_errno = errno;
 361
 362         if (!tdb)
 363                 return NULL;
 364
 365 #ifdef TDB_TRACE
 366         close(tdb->tracefd);
 367 #endif
 368         if (tdb->map_ptr) {
 369                 if (tdb->flags & TDB_INTERNAL) {
 370                         free(tdb->map_ptr);
 371                 } else
 372                         tdb_munmap(tdb);
 373         }
 374         free((char *)tdb->name);
 375         if (tdb->fd != -1)
 376                 if (close(tdb->fd) != 0)
 377                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 378                                  "tdb_open: failed to close tdb->fd"
 379                                  " on error!\n");
 380         free(tdb);
 381         errno = save_errno;
 382         return NULL;
 383 }
 384
 385 static tdb_off_t hash_off(struct tdb_context *tdb, uint64_t list)
 386 {
 387         return tdb->header.v.hash_off
 388                 + ((list & ((1ULL << tdb->header.v.hash_bits) - 1))
 389                    * sizeof(tdb_off_t));
 390 }
 391
 392 /* Returns 0 if the entry is a zero (definitely not a match).
 393  * Returns a valid entry offset if it's a match.  Fills in rec.
 394  * Otherwise returns TDB_OFF_ERR: keep searching. */
 395 static tdb_off_t entry_matches(struct tdb_context *tdb,
 396                                uint64_t list,
 397                                uint64_t hash,
 398                                const struct tdb_data *key,
 399                                struct tdb_used_record *rec)
 400 {
 401         tdb_off_t off;
 402         uint64_t keylen;
 403         const unsigned char *rkey;
 404
 405         off = tdb_read_off(tdb, tdb->header.v.hash_off
 406                            + list * sizeof(tdb_off_t));
 407         if (off == 0 || off == TDB_OFF_ERR)
 408                 return off;
 409
 410 #if 0 /* FIXME: Check other bits. */
 411         unsigned int bits, bitmask, hoffextra;
 412         /* Bottom three bits show how many extra hash bits. */
 413         bits = (off & ((1 << TDB_EXTRA_HASHBITS_NUM) - 1)) + 1;
 414         bitmask = (1 << bits)-1;
 415         hoffextra = ((off >> TDB_EXTRA_HASHBITS_NUM) & bitmask);
 416         uint64_t hextra = hash >> tdb->header.v.hash_bits;
 417         if ((hextra & bitmask) != hoffextra)
 418                 return TDB_OFF_ERR;
 419         off &= ~...;
 420 #endif
 421
 422         if (tdb_read_convert(tdb, off, rec, sizeof(*rec)) == -1)
 423                 return TDB_OFF_ERR;
 424
 425         /* FIXME: check extra bits in header! */
 426         keylen = rec_key_length(rec);
 427         if (keylen != key->dsize)
 428                 return TDB_OFF_ERR;
 429
 430         rkey = tdb_access_read(tdb, off + sizeof(*rec), keylen, false);
 431         if (!rkey)
 432                 return TDB_OFF_ERR;
 433         if (memcmp(rkey, key->dptr, keylen) != 0)
 434                 off = TDB_OFF_ERR;
 435         tdb_access_release(tdb, rkey);
 436         return off;
 437 }
 438
 439 /* FIXME: Optimize? */
 440 static void unlock_lists(struct tdb_context *tdb,
 441                          tdb_off_t list, tdb_len_t num,
 442                          int ltype)
 443 {
 444         tdb_off_t i;
 445
 446         for (i = list; i < list + num; i++)
 447                 tdb_unlock_list(tdb, i, ltype);
 448 }
 449
 450 /* FIXME: Optimize? */
 451 static int lock_lists(struct tdb_context *tdb,
 452                       tdb_off_t list, tdb_len_t num,
 453                       int ltype)
 454 {
 455         tdb_off_t i;
 456
 457         for (i = list; i < list + num; i++) {
 458                 if (tdb_lock_list(tdb, i, ltype, TDB_LOCK_WAIT) != 0) {
 459                         unlock_lists(tdb, list, i - list, ltype);
 460                         return -1;
 461                 }
 462         }
 463         return 0;
 464 }
 465
 466 /* We lock hashes up to the next empty offset.  We already hold the
 467  * lock on the start bucket, but we may need to release and re-grab
 468  * it.  If we fail, we hold no locks at all! */
 469 static tdb_len_t relock_hash_to_zero(struct tdb_context *tdb,
 470                                      tdb_off_t start, int ltype)
 471 {
 472         tdb_len_t num, len, pre_locks;
 473
 474 again:
 475         num = 1ULL << tdb->header.v.hash_bits;
 476         len = tdb_find_zero_off(tdb, hash_off(tdb, start), num - start);
 477         if (unlikely(len == num - start)) {
 478                 /* We hit the end of the hash range.  Drop lock: we have
 479                    to lock start of hash first. */
 480                 tdb_unlock_list(tdb, start, ltype);
 481                 /* Grab something, so header is stable. */
 482                 if (tdb_lock_list(tdb, 0, ltype, TDB_LOCK_WAIT))
 483                         return TDB_OFF_ERR;
 484                 len = tdb_find_zero_off(tdb, hash_off(tdb, 0), num);
 485                 if (lock_lists(tdb, 1, len, ltype) == -1) {
 486                         tdb_unlock_list(tdb, 0, ltype);
 487                         return TDB_OFF_ERR;
 488                 }
 489                 pre_locks = len;
 490                 len = num - start;
 491         } else {
 492                 /* We already have lock on start. */
 493                 start++;
 494                 pre_locks = 0;
 495         }
 496         if (unlikely(lock_lists(tdb, start, len, ltype) == -1)) {
 497                 if (pre_locks)
 498                         unlock_lists(tdb, 0, pre_locks, ltype);
 499                 else
 500                         tdb_unlock_list(tdb, start, ltype);
 501                 return TDB_OFF_ERR;
 502         }
 503
 504         /* Now, did we lose the race, and it's not zero any more? */
 505         if (unlikely(tdb_read_off(tdb, hash_off(tdb, pre_locks + len)) != 0)) {
 506                 unlock_lists(tdb, 0, pre_locks, ltype);
 507                 /* Leave the start locked, as expected. */
 508                 unlock_lists(tdb, start + 1, len - 1, ltype);
 509                 goto again;
 510         }
 511
 512         return pre_locks + len;
 513 }
 514
 515 /* FIXME: modify, don't rewrite! */
 516 static int update_rec_hdr(struct tdb_context *tdb,
 517                           tdb_off_t off,
 518                           tdb_len_t keylen,
 519                           tdb_len_t datalen,
 520                           struct tdb_used_record *rec,
 521                           uint64_t h)
 522 {
 523         uint64_t dataroom = rec_data_length(rec) + rec_extra_padding(rec);
 524
 525         if (set_header(tdb, rec, keylen, datalen, keylen + dataroom, h))
 526                 return -1;
 527
 528         return tdb_write_convert(tdb, off, rec, sizeof(*rec));
 529 }
 530
 531 /* If we fail, others will try after us. */
 532 static void enlarge_hash(struct tdb_context *tdb)
 533 {
 534         tdb_off_t newoff, oldoff, i;
 535         tdb_len_t hlen;
 536         uint64_t h, num = 1ULL << tdb->header.v.hash_bits;
 537         struct tdb_used_record pad, *r;
 538
 539         /* FIXME: We should do this without holding locks throughout. */
 540         if (tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false) == -1)
 541                 return;
 542
 543         /* Someone else enlarged for us?  Nothing to do. */
 544         if ((1ULL << tdb->header.v.hash_bits) != num)
 545                 goto unlock;
 546
 547         /* Allocate our new array. */
 548         hlen = num * sizeof(tdb_off_t) * 2;
 549         newoff = alloc(tdb, 0, hlen, 0, false);
 550         if (unlikely(newoff == TDB_OFF_ERR))
 551                 goto unlock;
 552         if (unlikely(newoff == 0)) {
 553                 if (tdb_expand(tdb, 0, hlen, false) == -1)
 554                         goto unlock;
 555                 newoff = alloc(tdb, 0, hlen, 0, false);
 556                 if (newoff == TDB_OFF_ERR || newoff == 0)
 557                         goto unlock;
 558         }
 559         /* Step over record header! */
 560         newoff += sizeof(struct tdb_used_record);
 561
 562         /* Starts all zero. */
 563         if (zero_out(tdb, newoff, hlen) == -1)
 564                 goto unlock;
 565
 566         /* FIXME: If the space before is empty, we know this is in its ideal
 567          * location.  Or steal a bit from the pointer to avoid rehash. */
 568         for (i = tdb_find_nonzero_off(tdb, hash_off(tdb, 0), num);
 569              i < num;
 570              i += tdb_find_nonzero_off(tdb, hash_off(tdb, i), num - i)) {
 571                 tdb_off_t off;
 572                 off = tdb_read_off(tdb, hash_off(tdb, i));
 573                 if (unlikely(off == TDB_OFF_ERR))
 574                         goto unlock;
 575                 if (unlikely(!off)) {
 576                         tdb->ecode = TDB_ERR_CORRUPT;
 577                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 578                                  "find_bucket_and_lock: zero hash bucket!\n");
 579                         goto unlock;
 580                 }
 581                 h = hash_record(tdb, off);
 582                 /* FIXME: Encode extra hash bits! */
 583                 if (tdb_write_off(tdb, newoff
 584                                   + (h & ((num * 2) - 1)) * sizeof(uint64_t),
 585                                   off) == -1)
 586                         goto unlock;
 587         }
 588
 589         /* Free up old hash. */
 590         oldoff = tdb->header.v.hash_off - sizeof(*r);
 591         r = tdb_get(tdb, oldoff, &pad, sizeof(*r));
 592         if (!r)
 593                 goto unlock;
 594         add_free_record(tdb, oldoff,
 595                         sizeof(*r)+rec_data_length(r)+rec_extra_padding(r));
 596
 597         /* Now we write the modified header. */
 598         tdb->header.v.hash_bits++;
 599         tdb->header.v.hash_off = newoff;
 600         write_header(tdb);
 601 unlock:
 602         tdb_allrecord_unlock(tdb, F_WRLCK);
 603 }
 604
 605 int tdb_store(struct tdb_context *tdb,
 606               struct tdb_data key, struct tdb_data dbuf, int flag)
 607 {
 608         tdb_off_t new_off, off, old_bucket, start, num_locks = 1;
 609         struct tdb_used_record rec;
 610         uint64_t h;
 611         bool growing = false;
 612
 613         h = tdb_hash(tdb, key.dptr, key.dsize);
 614
 615         /* FIXME: can we avoid locks for some fast paths? */
 616         start = tdb_lock_list(tdb, h, F_WRLCK, TDB_LOCK_WAIT);
 617         if (start == TDB_OFF_ERR)
 618                 return -1;
 619
 620         /* Fast path. */
 621         old_bucket = start;
 622         off = entry_matches(tdb, start, h, &key, &rec);
 623         if (unlikely(off == TDB_OFF_ERR)) {
 624                 /* Slow path, need to grab more locks and search. */
 625                 tdb_off_t i;
 626
 627                 /* Warning: this may drop the lock!  Does that on error. */
 628                 num_locks = relock_hash_to_zero(tdb, start, F_WRLCK);
 629                 if (num_locks == TDB_OFF_ERR)
 630                         return -1;
 631
 632                 for (i = start; i < start + num_locks; i++) {
 633                         off = entry_matches(tdb, i, h, &key, &rec);
 634                         /* Empty entry or we found it? */
 635                         if (off == 0 || off != TDB_OFF_ERR) {
 636                                 old_bucket = i;
 637                                 break;
 638                         }
 639                 }
 640                 if (i == start + num_locks)
 641                         off = 0;
 642         }
 643
 644         /* Now we have lock on this hash bucket. */
 645         if (flag == TDB_INSERT) {
 646                 if (off) {
 647                         tdb->ecode = TDB_ERR_EXISTS;
 648                         goto fail;
 649                 }
 650         } else {
 651                 if (off) {
 652                         if (rec_data_length(&rec) + rec_extra_padding(&rec)
 653                             >= dbuf.dsize) {
 654                                 new_off = off;
 655                                 if (update_rec_hdr(tdb, off,
 656                                                    key.dsize, dbuf.dsize,
 657                                                    &rec, h))
 658                                         goto fail;
 659                                 goto write;
 660                         }
 661                         /* FIXME: See if right record is free? */
 662                         /* Hint to allocator that we've realloced. */
 663                         growing = true;
 664                 } else {
 665                         if (flag == TDB_MODIFY) {
 666                                 /* if the record doesn't exist and we
 667                                    are in TDB_MODIFY mode then we should fail
 668                                    the store */
 669                                 tdb->ecode = TDB_ERR_NOEXIST;
 670                                 goto fail;
 671                         }
 672                 }
 673         }
 674
 675         /* Allocate a new record. */
 676         new_off = alloc(tdb, key.dsize, dbuf.dsize, h, growing);
 677         if (new_off == 0) {
 678                 unlock_lists(tdb, start, num_locks, F_WRLCK);
 679                 /* Expand, then try again... */
 680                 if (tdb_expand(tdb, key.dsize, dbuf.dsize, growing) == -1)
 681                         return -1;
 682                 return tdb_store(tdb, key, dbuf, flag);
 683         }
 684
 685         /* We didn't like the existing one: remove it. */
 686         if (off) {
 687                 add_free_record(tdb, off, sizeof(struct tdb_used_record)
 688                                 + rec_key_length(&rec)
 689                                 + rec_data_length(&rec)
 690                                 + rec_extra_padding(&rec));
 691         }
 692
 693         /* FIXME: Encode extra hash bits! */
 694         if (tdb_write_off(tdb, hash_off(tdb, old_bucket), new_off) == -1)
 695                 goto fail;
 696
 697 write:
 698         off = new_off + sizeof(struct tdb_used_record);
 699         if (tdb->methods->write(tdb, off, key.dptr, key.dsize) == -1)
 700                 goto fail;
 701         off += key.dsize;
 702         if (tdb->methods->write(tdb, off, dbuf.dptr, dbuf.dsize) == -1)
 703                 goto fail;
 704
 705         /* FIXME: tdb_increment_seqnum(tdb); */
 706         unlock_lists(tdb, start, num_locks, F_WRLCK);
 707
 708         /* FIXME: by simple simulation, this approximated 60% full.
 709          * Check in real case! */
 710         if (unlikely(num_locks > 4 * tdb->header.v.hash_bits - 31))
 711                 enlarge_hash(tdb);
 712
 713         return 0;
 714
 715 fail:
 716         unlock_lists(tdb, start, num_locks, F_WRLCK);
 717         return -1;
 718 }
 719
 720 struct tdb_data tdb_fetch(struct tdb_context *tdb, struct tdb_data key)
 721 {
 722         tdb_off_t off, start, num_locks = 1;
 723         struct tdb_used_record rec;
 724         uint64_t h;
 725         struct tdb_data ret;
 726
 727         h = tdb_hash(tdb, key.dptr, key.dsize);
 728
 729         /* FIXME: can we avoid locks for some fast paths? */
 730         start = tdb_lock_list(tdb, h, F_RDLCK, TDB_LOCK_WAIT);
 731         if (start == TDB_OFF_ERR)
 732                 return tdb_null;
 733
 734         /* Fast path. */
 735         off = entry_matches(tdb, start, h, &key, &rec);
 736         if (unlikely(off == TDB_OFF_ERR)) {
 737                 /* Slow path, need to grab more locks and search. */
 738                 tdb_off_t i;
 739
 740                 /* Warning: this may drop the lock!  Does that on error. */
 741                 num_locks = relock_hash_to_zero(tdb, start, F_RDLCK);
 742                 if (num_locks == TDB_OFF_ERR)
 743                         return tdb_null;
 744
 745                 for (i = start; i < start + num_locks; i++) {
 746                         off = entry_matches(tdb, i, h, &key, &rec);
 747                         /* Empty entry or we found it? */
 748                         if (off == 0 || off != TDB_OFF_ERR)
 749                                 break;
 750                 }
 751                 if (i == start + num_locks)
 752                         off = 0;
 753         }
 754
 755         if (!off) {
 756                 unlock_lists(tdb, start, num_locks, F_RDLCK);
 757                 tdb->ecode = TDB_ERR_NOEXIST;
 758                 return tdb_null;
 759         }
 760
 761         ret.dsize = rec_data_length(&rec);
 762         ret.dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
 763                                   ret.dsize);
 764         unlock_lists(tdb, start, num_locks, F_RDLCK);
 765         return ret;
 766 }
 767
 768 static int hash_add(struct tdb_context *tdb, uint64_t h, tdb_off_t off)
 769 {
 770         tdb_off_t i, hoff, len, num;
 771
 772         /* Look for next space. */
 773         i = (h & ((1ULL << tdb->header.v.hash_bits) - 1));
 774         len = (1ULL << tdb->header.v.hash_bits) - i;
 775         num = tdb_find_zero_off(tdb, hash_off(tdb, i), len);
 776
 777         if (unlikely(num == len)) {
 778                 /* We wrapped.  Look through start of hash table. */
 779                 hoff = hash_off(tdb, 0);
 780                 len = (1ULL << tdb->header.v.hash_bits);
 781                 num = tdb_find_zero_off(tdb, hoff, len);
 782                 if (i == len) {
 783                         tdb->ecode = TDB_ERR_CORRUPT;
 784                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 785                                  "hash_add: full hash table!\n");
 786                         return -1;
 787                 }
 788         }
 789         /* FIXME: Encode extra hash bits! */
 790         return tdb_write_off(tdb, hash_off(tdb, i + num), off);
 791 }
 792
 793 int tdb_delete(struct tdb_context *tdb, struct tdb_data key)
 794 {
 795         tdb_off_t i, old_bucket, off, start, num_locks = 1;
 796         struct tdb_used_record rec;
 797         uint64_t h;
 798
 799         h = tdb_hash(tdb, key.dptr, key.dsize);
 800
 801         /* FIXME: can we avoid locks for some fast paths? */
 802         start = tdb_lock_list(tdb, h, F_WRLCK, TDB_LOCK_WAIT);
 803         if (start == TDB_OFF_ERR)
 804                 return -1;
 805
 806         /* Fast path. */
 807         old_bucket = start;
 808         off = entry_matches(tdb, start, h, &key, &rec);
 809         if (off && off != TDB_OFF_ERR) {
 810                 /* We can only really fastpath delete if next bucket
 811                  * is 0.  Note that we haven't locked it, but our lock
 812                  * on this bucket stops anyone overflowing into it
 813                  * while we look. */
 814                 if (tdb_read_off(tdb, hash_off(tdb, h+1)) == 0)
 815                         goto delete;
 816                 /* Slow path. */
 817                 off = TDB_OFF_ERR;
 818         }
 819
 820         if (unlikely(off == TDB_OFF_ERR)) {
 821                 /* Slow path, need to grab more locks and search. */
 822                 tdb_off_t i;
 823
 824                 /* Warning: this may drop the lock!  Does that on error. */
 825                 num_locks = relock_hash_to_zero(tdb, start, F_WRLCK);
 826                 if (num_locks == TDB_OFF_ERR)
 827                         return -1;
 828
 829                 for (i = start; i < start + num_locks; i++) {
 830                         off = entry_matches(tdb, i, h, &key, &rec);
 831                         /* Empty entry or we found it? */
 832                         if (off == 0 || off != TDB_OFF_ERR) {
 833                                 old_bucket = i;
 834                                 break;
 835                         }
 836                 }
 837                 if (i == start + num_locks)
 838                         off = 0;
 839         }
 840
 841         if (!off) {
 842                 unlock_lists(tdb, start, num_locks, F_WRLCK);
 843                 tdb->ecode = TDB_ERR_NOEXIST;
 844                 return -1;
 845         }
 846
 847 delete:
 848         /* This actually unlinks it. */
 849         if (tdb_write_off(tdb, hash_off(tdb, old_bucket), 0) == -1)
 850                 goto unlock_err;
 851
 852         /* Rehash anything following. */
 853         for (i = hash_off(tdb, old_bucket+1);
 854              i != hash_off(tdb, h + num_locks);
 855              i += sizeof(tdb_off_t)) {
 856                 tdb_off_t off2;
 857                 uint64_t h2;
 858
 859                 off2 = tdb_read_off(tdb, i);
 860                 if (unlikely(off2 == TDB_OFF_ERR))
 861                         goto unlock_err;
 862
 863                 /* Maybe use a bit to indicate it is in ideal place? */
 864                 h2 = hash_record(tdb, off2);
 865                 /* Is it happy where it is? */
 866                 if (hash_off(tdb, h2) == i)
 867                         continue;
 868
 869                 /* Remove it. */
 870                 if (tdb_write_off(tdb, i, 0) == -1)
 871                         goto unlock_err;
 872
 873                 /* Rehash it. */
 874                 if (hash_add(tdb, h2, off2) == -1)
 875                         goto unlock_err;
 876         }
 877
 878         /* Free the deleted entry. */
 879         if (add_free_record(tdb, off,
 880                             sizeof(struct tdb_used_record)
 881                             + rec_key_length(&rec)
 882                             + rec_data_length(&rec)
 883                             + rec_extra_padding(&rec)) != 0)
 884                 goto unlock_err;
 885
 886         unlock_lists(tdb, start, num_locks, F_WRLCK);
 887         return 0;
 888
 889 unlock_err:
 890         unlock_lists(tdb, start, num_locks, F_WRLCK);
 891         return -1;
 892 }
 893
 894 int tdb_close(struct tdb_context *tdb)
 895 {
 896         struct tdb_context **i;
 897         int ret = 0;
 898
 899         /* FIXME:
 900         if (tdb->transaction) {
 901                 tdb_transaction_cancel(tdb);
 902         }
 903         */
 904         tdb_trace(tdb, "tdb_close");
 905
 906         if (tdb->map_ptr) {
 907                 if (tdb->flags & TDB_INTERNAL)
 908                         free(tdb->map_ptr);
 909                 else
 910                         tdb_munmap(tdb);
 911         }
 912         free((char *)tdb->name);
 913         if (tdb->fd != -1) {
 914                 ret = close(tdb->fd);
 915                 tdb->fd = -1;
 916         }
 917         free(tdb->lockrecs);
 918
 919         /* Remove from contexts list */
 920         for (i = &tdbs; *i; i = &(*i)->next) {
 921                 if (*i == tdb) {
 922                         *i = tdb->next;
 923                         break;
 924                 }
 925         }
 926
 927 #ifdef TDB_TRACE
 928         close(tdb->tracefd);
 929 #endif
 930         free(tdb);
 931
 932         return ret;
 933 }
 934
 935 enum TDB_ERROR tdb_error(struct tdb_context *tdb)
 936 {
 937         return tdb->ecode;
 938 }