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