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/likely/likely.h>
   5 #include <assert.h>
   6
   7 /* The null return. */
   8 struct tdb_data tdb_null = { .dptr = NULL, .dsize = 0 };
   9
  10 /* all contexts, to ensure no double-opens (fcntl locks don't nest!) */
  11 static struct tdb_context *tdbs = NULL;
  12
  13 PRINTF_ATTRIBUTE(4, 5) static void
  14 null_log_fn(struct tdb_context *tdb,
  15             enum tdb_debug_level level, void *priv,
  16             const char *fmt, ...)
  17 {
  18 }
  19
  20 /* We do a lot of work assuming our copy of the header volatile area
  21  * is uptodate, and usually it is.  However, once we grab a lock, we have to
  22  * re-check it. */
  23 bool update_header(struct tdb_context *tdb)
  24 {
  25         struct tdb_header_volatile pad, *v;
  26
  27         if (tdb->header_uptodate) {
  28                 tdb->log(tdb, TDB_DEBUG_WARNING, tdb->log_priv,
  29                          "warning: header uptodate already\n");
  30         }
  31
  32         /* We could get a partial update if we're not holding any locks. */
  33         assert(tdb_has_locks(tdb));
  34
  35         v = tdb_get(tdb, offsetof(struct tdb_header, v), &pad, sizeof(*v));
  36         if (!v) {
  37                 /* On failure, imply we updated header so they retry. */
  38                 return true;
  39         }
  40         tdb->header_uptodate = true;
  41         if (likely(memcmp(&tdb->header.v, v, sizeof(*v)) == 0)) {
  42                 return false;
  43         }
  44         tdb->header.v = *v;
  45         return true;
  46 }
  47
  48 static uint64_t jenkins_hash(const void *key, size_t length, uint64_t seed,
  49                              void *arg)
  50 {
  51         return hash64_any(key, length, seed);
  52 }
  53
  54 uint64_t tdb_hash(struct tdb_context *tdb, const void *ptr, size_t len)
  55 {
  56         return tdb->khash(ptr, len, tdb->header.hash_seed, tdb->hash_priv);
  57 }
  58
  59 static bool tdb_already_open(dev_t device, ino_t ino)
  60 {
  61         struct tdb_context *i;
  62
  63         for (i = tdbs; i; i = i->next) {
  64                 if (i->device == device && i->inode == ino) {
  65                         return true;
  66                 }
  67         }
  68
  69         return false;
  70 }
  71
  72 static uint64_t random_number(struct tdb_context *tdb)
  73 {
  74         int fd;
  75         uint64_t ret = 0;
  76         struct timeval now;
  77
  78         fd = open("/dev/urandom", O_RDONLY);
  79         if (fd >= 0) {
  80                 if (read(fd, &ret, sizeof(ret)) == sizeof(ret)) {
  81                         tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
  82                                  "tdb_open: random from /dev/urandom\n");
  83                         close(fd);
  84                         return ret;
  85                 }
  86                 close(fd);
  87         }
  88         /* FIXME: Untested!  Based on Wikipedia protocol description! */
  89         fd = open("/dev/egd-pool", O_RDWR);
  90         if (fd >= 0) {
  91                 /* Command is 1, next byte is size we want to read. */
  92                 char cmd[2] = { 1, sizeof(uint64_t) };
  93                 if (write(fd, cmd, sizeof(cmd)) == sizeof(cmd)) {
  94                         char reply[1 + sizeof(uint64_t)];
  95                         int r = read(fd, reply, sizeof(reply));
  96                         if (r > 1) {
  97                                 tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
  98                                          "tdb_open: %u random bytes from"
  99                                          " /dev/egd-pool\n", r-1);
 100                                 /* Copy at least some bytes. */
 101                                 memcpy(&ret, reply+1, r - 1);
 102                                 if (reply[0] == sizeof(uint64_t)
 103                                     && r == sizeof(reply)) {
 104                                         close(fd);
 105                                         return ret;
 106                                 }
 107                         }
 108                 }
 109                 close(fd);
 110         }
 111
 112         /* Fallback: pid and time. */
 113         gettimeofday(&now, NULL);
 114         ret = getpid() * 100132289ULL + now.tv_sec * 1000000ULL + now.tv_usec;
 115         tdb->log(tdb, TDB_DEBUG_TRACE, tdb->log_priv,
 116                  "tdb_open: random from getpid and time\n");
 117         return ret;
 118 }
 119
 120 struct new_database {
 121         struct tdb_header hdr;
 122         struct tdb_used_record hrec;
 123         tdb_off_t hash[1ULL << INITIAL_HASH_BITS];
 124         struct tdb_used_record frec;
 125         tdb_off_t free[INITIAL_FREE_BUCKETS + 1]; /* One overflow bucket */
 126 };
 127
 128 /* initialise a new database */
 129 static int tdb_new_database(struct tdb_context *tdb)
 130 {
 131         /* We make it up in memory, then write it out if not internal */
 132         struct new_database newdb;
 133
 134         /* Fill in the header */
 135         newdb.hdr.version = TDB_VERSION;
 136         newdb.hdr.hash_seed = random_number(tdb);
 137         newdb.hdr.hash_test = TDB_HASH_MAGIC;
 138         newdb.hdr.hash_test = tdb->khash(&newdb.hdr.hash_test,
 139                                          sizeof(newdb.hdr.hash_test),
 140                                          newdb.hdr.hash_seed,
 141                                          tdb->hash_priv);
 142
 143         newdb.hdr.v.generation = 0;
 144
 145         /* Free array has 1 zone, 10 buckets.  All buckets empty. */
 146         newdb.hdr.v.num_zones = 1;
 147         newdb.hdr.v.zone_bits = INITIAL_ZONE_BITS;
 148         newdb.hdr.v.free_buckets = INITIAL_FREE_BUCKETS;
 149         newdb.hdr.v.free_off = offsetof(struct new_database, free);
 150         set_header(tdb, &newdb.frec, 0,
 151                    sizeof(newdb.free), sizeof(newdb.free), 0);
 152         memset(newdb.free, 0, sizeof(newdb.free));
 153
 154         /* Initial hashes are empty. */
 155         newdb.hdr.v.hash_bits = INITIAL_HASH_BITS;
 156         newdb.hdr.v.hash_off = offsetof(struct new_database, hash);
 157         set_header(tdb, &newdb.hrec, 0,
 158                    sizeof(newdb.hash), sizeof(newdb.hash), 0);
 159         memset(newdb.hash, 0, sizeof(newdb.hash));
 160
 161         if (tdb->flags & TDB_INTERNAL) {
 162                 tdb->map_size = sizeof(newdb);
 163                 tdb->map_ptr = malloc(tdb->map_size);
 164                 if (!tdb->map_ptr) {
 165                         tdb->ecode = TDB_ERR_OOM;
 166                         return -1;
 167                 }
 168                 memcpy(tdb->map_ptr, &newdb, tdb->map_size);
 169                 tdb->header = newdb.hdr;
 170                 /* Convert the `ondisk' version if asked. */
 171                 tdb_convert(tdb, tdb->map_ptr, sizeof(newdb));
 172                 return 0;
 173         }
 174         if (lseek(tdb->fd, 0, SEEK_SET) == -1)
 175                 return -1;
 176
 177         if (ftruncate(tdb->fd, 0) == -1)
 178                 return -1;
 179
 180         /* This creates an endian-converted header, as if read from disk */
 181         tdb->header = newdb.hdr;
 182         tdb_convert(tdb, &tdb->header, sizeof(tdb->header));
 183
 184         /* Don't endian-convert the magic food! */
 185         memset(newdb.hdr.magic_food, 0, sizeof(newdb.hdr.magic_food));
 186         strcpy(newdb.hdr.magic_food, TDB_MAGIC_FOOD);
 187
 188         if (!tdb_pwrite_all(tdb->fd, &newdb, sizeof(newdb), 0)) {
 189                 tdb->ecode = TDB_ERR_IO;
 190                 return -1;
 191         }
 192         return 0;
 193 }
 194
 195 struct tdb_context *tdb_open(const char *name, int tdb_flags,
 196                              int open_flags, mode_t mode,
 197                              union tdb_attribute *attr)
 198 {
 199         struct tdb_context *tdb;
 200         struct stat st;
 201         int save_errno;
 202         uint64_t hash_test;
 203         unsigned v;
 204
 205         if (!(tdb = (struct tdb_context *)calloc(1, sizeof *tdb))) {
 206                 /* Can't log this */
 207                 errno = ENOMEM;
 208                 goto fail;
 209         }
 210         tdb->fd = -1;
 211         tdb->name = NULL;
 212         tdb->map_ptr = NULL;
 213         tdb->flags = tdb_flags;
 214         tdb->log = null_log_fn;
 215         tdb->log_priv = NULL;
 216         tdb->khash = jenkins_hash;
 217         tdb->hash_priv = NULL;
 218
 219         /* FIXME */
 220         if (attr) {
 221                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 222                          "tdb_open: attributes not yet supported\n");
 223                 errno = EINVAL;
 224                 goto fail;
 225         }
 226
 227         if ((open_flags & O_ACCMODE) == O_WRONLY) {
 228                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 229                          "tdb_open: can't open tdb %s write-only\n", name);
 230                 errno = EINVAL;
 231                 goto fail;
 232         }
 233
 234         if ((open_flags & O_ACCMODE) == O_RDONLY) {
 235                 tdb->read_only = 1;
 236                 /* read only databases don't do locking */
 237                 tdb->flags |= TDB_NOLOCK;
 238         }
 239
 240         /* internal databases don't mmap or lock */
 241         if (tdb->flags & TDB_INTERNAL) {
 242                 tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
 243                 if (tdb_new_database(tdb) != 0) {
 244                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 245                                  "tdb_open: tdb_new_database failed!");
 246                         goto fail;
 247                 }
 248                 TEST_IT(tdb->flags & TDB_CONVERT);
 249                 goto internal;
 250         }
 251
 252         if ((tdb->fd = open(name, open_flags, mode)) == -1) {
 253                 tdb->log(tdb, TDB_DEBUG_WARNING, tdb->log_priv,
 254                          "tdb_open: could not open file %s: %s\n",
 255                          name, strerror(errno));
 256                 goto fail;      /* errno set by open(2) */
 257         }
 258
 259         /* on exec, don't inherit the fd */
 260         v = fcntl(tdb->fd, F_GETFD, 0);
 261         fcntl(tdb->fd, F_SETFD, v | FD_CLOEXEC);
 262
 263         /* ensure there is only one process initialising at once */
 264         if (tdb_lock_open(tdb) == -1) {
 265                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 266                          "tdb_open: failed to get open lock on %s: %s\n",
 267                          name, strerror(errno));
 268                 goto fail;      /* errno set by tdb_brlock */
 269         }
 270
 271         errno = 0;
 272         if (read(tdb->fd, &tdb->header, sizeof(tdb->header)) != sizeof(tdb->header)
 273             || strcmp(tdb->header.magic_food, TDB_MAGIC_FOOD) != 0) {
 274                 if (!(open_flags & O_CREAT) || tdb_new_database(tdb) == -1) {
 275                         if (errno == 0) {
 276                                 errno = EIO; /* ie bad format or something */
 277                         }
 278                         goto fail;
 279                 }
 280         } else if (tdb->header.version != TDB_VERSION) {
 281                 if (tdb->header.version == bswap_64(TDB_VERSION))
 282                         tdb->flags |= TDB_CONVERT;
 283                 else {
 284                         /* wrong version */
 285                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 286                                  "tdb_open: %s is unknown version 0x%llx\n",
 287                                  name, (long long)tdb->header.version);
 288                         errno = EIO;
 289                         goto fail;
 290                 }
 291         }
 292
 293         tdb_convert(tdb, &tdb->header, sizeof(tdb->header));
 294         hash_test = TDB_HASH_MAGIC;
 295         hash_test = tdb->khash(&hash_test, sizeof(hash_test),
 296                                tdb->header.hash_seed, tdb->hash_priv);
 297         if (tdb->header.hash_test != hash_test) {
 298                 /* wrong hash variant */
 299                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 300                          "tdb_open: %s uses a different hash function\n",
 301                          name);
 302                 errno = EIO;
 303                 goto fail;
 304         }
 305
 306         if (fstat(tdb->fd, &st) == -1)
 307                 goto fail;
 308
 309         /* Is it already in the open list?  If so, fail. */
 310         if (tdb_already_open(st.st_dev, st.st_ino)) {
 311                 /* FIXME */
 312                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 313                          "tdb_open: %s (%d,%d) is already open in this process\n",
 314                          name, (int)st.st_dev, (int)st.st_ino);
 315                 errno = EBUSY;
 316                 goto fail;
 317         }
 318
 319         tdb->name = strdup(name);
 320         if (!tdb->name) {
 321                 errno = ENOMEM;
 322                 goto fail;
 323         }
 324
 325         tdb->map_size = st.st_size;
 326         tdb->device = st.st_dev;
 327         tdb->inode = st.st_ino;
 328         tdb_io_init(tdb);
 329         tdb_mmap(tdb);
 330
 331  internal:
 332         /* Internal (memory-only) databases skip all the code above to
 333          * do with disk files, and resume here by releasing their
 334          * open lock and hooking into the active list. */
 335         tdb_unlock_open(tdb);
 336         tdb->last_zone = random_free_zone(tdb);
 337         tdb->next = tdbs;
 338         tdbs = tdb;
 339         return tdb;
 340
 341  fail:
 342         save_errno = errno;
 343
 344         if (!tdb)
 345                 return NULL;
 346
 347 #ifdef TDB_TRACE
 348         close(tdb->tracefd);
 349 #endif
 350         if (tdb->map_ptr) {
 351                 if (tdb->flags & TDB_INTERNAL) {
 352                         free(tdb->map_ptr);
 353                 } else
 354                         tdb_munmap(tdb);
 355         }
 356         free((char *)tdb->name);
 357         if (tdb->fd != -1)
 358                 if (close(tdb->fd) != 0)
 359                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 360                                  "tdb_open: failed to close tdb->fd"
 361                                  " on error!\n");
 362         free(tdb);
 363         errno = save_errno;
 364         return NULL;
 365 }
 366
 367 static int tdb_key_compare(TDB_DATA key, TDB_DATA data, void *private_data)
 368 {
 369         return memcmp(data.dptr, key.dptr, data.dsize) == 0;
 370 }
 371
 372 static void unlock_lists(struct tdb_context *tdb,
 373                          uint64_t start, uint64_t end, int ltype)
 374 {
 375         do {
 376                 tdb_unlock_list(tdb, start, ltype);
 377                 start = (start + ((1ULL << tdb->header.v.hash_bits) - 1))
 378                         & ((1ULL << tdb->header.v.hash_bits) - 1);
 379         } while (start != end);
 380 }
 381
 382 /* FIXME: Return header copy? */
 383 /* Returns -1 or offset of entry (0 if not found).
 384  * Locks hash entried from *start to *end (where the entry was found). */
 385 static tdb_off_t find_bucket_and_lock(struct tdb_context *tdb,
 386                                       const struct tdb_data *key,
 387                                       uint64_t hash,
 388                                       uint64_t *start,
 389                                       uint64_t *end,
 390                                       uint64_t *room,
 391                                       int ltype)
 392 {
 393         uint64_t hextra;
 394         tdb_off_t off;
 395
 396         /* hash_bits might be out of date... */
 397 again:
 398         *start = *end = hash & ((1ULL << tdb->header.v.hash_bits) - 1);
 399         hextra = hash >> tdb->header.v.hash_bits;
 400
 401         /* FIXME: can we avoid locks for some fast paths? */
 402         if (tdb_lock_list(tdb, *end, ltype, TDB_LOCK_WAIT) == -1)
 403                 return TDB_OFF_ERR;
 404
 405         /* We only need to check this for first lock. */
 406         if (unlikely(update_header(tdb))) {
 407                 tdb_unlock_list(tdb, *end, ltype);
 408                 goto again;
 409         }
 410
 411         while ((off = tdb_read_off(tdb, tdb->header.v.hash_off
 412                                    + *end * sizeof(tdb_off_t)))
 413                != TDB_OFF_ERR) {
 414                 struct tdb_used_record pad, *r;
 415                 uint64_t keylen, next;
 416
 417                 /* Didn't find it? */
 418                 if (!off)
 419                         return 0;
 420
 421 #if 0 /* FIXME: Check other bits. */
 422                 unsigned int bits, bitmask, hoffextra;
 423                 /* Bottom three bits show how many extra hash bits. */
 424                 bits = (off & ((1 << TDB_EXTRA_HASHBITS_NUM) - 1)) + 1;
 425                 bitmask = (1 << bits)-1;
 426                 hoffextra = ((off >> TDB_EXTRA_HASHBITS_NUM) & bitmask);
 427                 if ((hextra & bitmask) != hoffextra)
 428                         goto lock_next;
 429 #endif
 430
 431                 r = tdb_get(tdb, off, &pad, sizeof(*r));
 432                 if (!r)
 433                         goto unlock_err;
 434
 435                 if (rec_magic(r) != TDB_MAGIC) {
 436                         tdb->ecode = TDB_ERR_CORRUPT;
 437                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 438                                  "find_bucket_and_lock: bad magic 0x%llx"
 439                                  " at offset %llu!\n",
 440                                  (long long)rec_magic(r), (long long)off);
 441                         goto unlock_err;
 442                 }
 443
 444                 /* FIXME: check extra bits in header! */
 445                 keylen = rec_key_length(r);
 446                 if (keylen != key->dsize)
 447                         goto lock_next;
 448
 449                 switch (tdb_parse_data(tdb, *key, off + sizeof(*r), key->dsize,
 450                                        tdb_key_compare, NULL)) {
 451                 case 1:
 452                         /* Match! */
 453                         *room = rec_data_length(r) + rec_extra_padding(r);
 454                         return off >> TDB_EXTRA_HASHBITS_NUM;
 455                 case 0:
 456                         break;
 457                 default:
 458                         goto unlock_err;
 459                 }
 460
 461         lock_next:
 462                 /* Lock next bucket. */
 463                 /* FIXME: We can deadlock if this wraps! */
 464                 next = (*end + 1) & ((1ULL << tdb->header.v.hash_bits) - 1);
 465                 if (next == *start) {
 466                         tdb->ecode = TDB_ERR_CORRUPT;
 467                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 468                                  "find_bucket_and_lock: full hash table!\n");
 469                         goto unlock_err;
 470                 }
 471                 if (tdb_lock_list(tdb, next, ltype, TDB_LOCK_WAIT) == -1)
 472                         goto unlock_err;
 473                 *end = next;
 474         }
 475
 476 unlock_err:
 477         TEST_IT(*end < *start);
 478         unlock_lists(tdb, *start, *end, ltype);
 479         return TDB_OFF_ERR;
 480 }
 481
 482 static int update_rec_hdr(struct tdb_context *tdb,
 483                           tdb_off_t off,
 484                           tdb_len_t keylen,
 485                           tdb_len_t datalen,
 486                           tdb_len_t room,
 487                           uint64_t h)
 488 {
 489         struct tdb_used_record rec;
 490
 491         if (set_header(tdb, &rec, keylen, datalen, room - datalen, h))
 492                 return -1;
 493
 494         return tdb_write_convert(tdb, off, &rec, sizeof(rec));
 495 }
 496
 497 /* If we fail, others will try after us. */
 498 static void enlarge_hash(struct tdb_context *tdb)
 499 {
 500         tdb_off_t newoff, i;
 501         uint64_t h, num = 1ULL << tdb->header.v.hash_bits;
 502         struct tdb_used_record pad, *r;
 503
 504         /* FIXME: We should do this without holding locks throughout. */
 505         if (tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false) == -1)
 506                 return;
 507
 508         if (unlikely(update_header(tdb))) {
 509                 /* Someone else enlarged for us?  Nothing to do. */
 510                 if ((1ULL << tdb->header.v.hash_bits) != num)
 511                         goto unlock;
 512         }
 513
 514         newoff = alloc(tdb, 0, num * 2, 0, false);
 515         if (unlikely(newoff == TDB_OFF_ERR))
 516                 goto unlock;
 517         if (unlikely(newoff == 0)) {
 518                 if (tdb_expand(tdb, 0, num * 2, false) == -1)
 519                         goto unlock;
 520                 newoff = alloc(tdb, 0, num * 2, 0, false);
 521                 if (newoff == TDB_OFF_ERR || newoff == 0)
 522                         goto unlock;
 523         }
 524
 525         /* FIXME: If the space before is empty, we know this is in its ideal
 526          * location.  We can steal a bit from the pointer to avoid rehash. */
 527         for (i = tdb_find_nonzero_off(tdb, tdb->header.v.hash_off, num);
 528              i < num;
 529              i += tdb_find_nonzero_off(tdb, tdb->header.v.hash_off
 530                                        + i*sizeof(tdb_off_t), num - i)) {
 531                 tdb_off_t off;
 532                 off = tdb_read_off(tdb, tdb->header.v.hash_off
 533                                    + i*sizeof(tdb_off_t));
 534                 if (unlikely(off == TDB_OFF_ERR))
 535                         goto unlock;
 536                 if (unlikely(!off)) {
 537                         tdb->ecode = TDB_ERR_CORRUPT;
 538                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 539                                  "find_bucket_and_lock: zero hash bucket!\n");
 540                         goto unlock;
 541                 }
 542                 h = hash_record(tdb, off);
 543                 /* FIXME: Encode extra hash bits! */
 544                 if (tdb_write_off(tdb, newoff
 545                                   + (h & ((num * 2) - 1)) * sizeof(uint64_t),
 546                                   off) == -1)
 547                         goto unlock;
 548         }
 549
 550         /* Free up old hash. */
 551         r = tdb_get(tdb, tdb->header.v.hash_off, &pad, sizeof(*r));
 552         if (!r)
 553                 goto unlock;
 554         add_free_record(tdb, tdb->header.v.hash_off,
 555                         rec_data_length(r) + rec_extra_padding(r));
 556
 557         /* Now we write the modified header. */
 558         tdb->header.v.generation++;
 559         tdb->header.v.hash_bits++;
 560         tdb->header.v.hash_off = newoff;
 561         tdb_write_convert(tdb, offsetof(struct tdb_header, v),
 562                           &tdb->header.v, sizeof(tdb->header.v));
 563 unlock:
 564         tdb_allrecord_unlock(tdb, F_WRLCK);
 565 }
 566
 567 int tdb_store(struct tdb_context *tdb,
 568               struct tdb_data key, struct tdb_data dbuf, int flag)
 569 {
 570         tdb_off_t new_off, off, start, end, room;
 571         uint64_t h;
 572         bool growing = false;
 573
 574         h = tdb_hash(tdb, key.dptr, key.dsize);
 575         off = find_bucket_and_lock(tdb, &key, h, &start, &end, &room, F_WRLCK);
 576         if (off == TDB_OFF_ERR)
 577                 return -1;
 578
 579         /* Now we have lock on this hash bucket. */
 580         if (flag == TDB_INSERT) {
 581                 if (off) {
 582                         tdb->ecode = TDB_ERR_EXISTS;
 583                         goto fail;
 584                 }
 585         } else {
 586                 if (off) {
 587                         if (room >= key.dsize + dbuf.dsize) {
 588                                 new_off = off;
 589                                 if (update_rec_hdr(tdb, off,
 590                                                    key.dsize, dbuf.dsize,
 591                                                    room, h))
 592                                         goto fail;
 593                                 goto write;
 594                         }
 595                         /* FIXME: See if right record is free? */
 596                         /* Hint to allocator that we've realloced. */
 597                         growing = true;
 598                 } else {
 599                         if (flag == TDB_MODIFY) {
 600                                 /* if the record doesn't exist and we
 601                                    are in TDB_MODIFY mode then we should fail
 602                                    the store */
 603                                 tdb->ecode = TDB_ERR_NOEXIST;
 604                                 goto fail;
 605                         }
 606                 }
 607         }
 608
 609         /* Allocate a new record. */
 610         new_off = alloc(tdb, key.dsize, dbuf.dsize, h, growing);
 611         if (new_off == 0) {
 612                 unlock_lists(tdb, start, end, F_WRLCK);
 613                 /* Expand, then try again... */
 614                 if (tdb_expand(tdb, key.dsize, dbuf.dsize, growing) == -1)
 615                         return -1;
 616                 return tdb_store(tdb, key, dbuf, flag);
 617         }
 618
 619         /* We didn't like the existing one: remove it. */
 620         if (off) {
 621                 add_free_record(tdb, off, sizeof(struct tdb_used_record)
 622                                 + key.dsize + room);
 623         }
 624
 625 write:
 626         off = tdb->header.v.hash_off + end * sizeof(tdb_off_t);
 627         /* FIXME: Encode extra hash bits! */
 628         if (tdb_write_off(tdb, off, new_off) == -1)
 629                 goto fail;
 630
 631         off = new_off + sizeof(struct tdb_used_record);
 632         if (tdb->methods->write(tdb, off, key.dptr, key.dsize) == -1)
 633                 goto fail;
 634         off += key.dsize;
 635         if (tdb->methods->write(tdb, off, dbuf.dptr, dbuf.dsize) == -1)
 636                 goto fail;
 637
 638         /* FIXME: tdb_increment_seqnum(tdb); */
 639         unlock_lists(tdb, start, end, F_WRLCK);
 640
 641         /* By simple trial and error, this roughly approximates a 60%
 642          * full measure. */
 643         if (unlikely(end - start > 4 * tdb->header.v.hash_bits - 32))
 644                 enlarge_hash(tdb);
 645
 646         return 0;
 647
 648 fail:
 649         unlock_lists(tdb, start, end, F_WRLCK);
 650         return -1;
 651 }
 652
 653 struct tdb_data tdb_fetch(struct tdb_context *tdb, struct tdb_data key)
 654 {
 655         tdb_off_t off, start, end, room;
 656         uint64_t h;
 657         struct tdb_used_record pad, *r;
 658         struct tdb_data ret;
 659
 660         h = tdb_hash(tdb, key.dptr, key.dsize);
 661         off = find_bucket_and_lock(tdb, &key, h, &start, &end, &room, F_RDLCK);
 662         if (off == TDB_OFF_ERR)
 663                 return tdb_null;
 664
 665         if (!off) {
 666                 unlock_lists(tdb, start, end, F_RDLCK);
 667                 tdb->ecode = TDB_SUCCESS;
 668                 return tdb_null;
 669         }
 670
 671         r = tdb_get(tdb, off, &pad, sizeof(*r));
 672         if (!r) {
 673                 unlock_lists(tdb, start, end, F_RDLCK);
 674                 return tdb_null;
 675         }
 676
 677         ret.dsize = rec_data_length(r);
 678         ret.dptr = tdb_alloc_read(tdb, off + sizeof(*r) + key.dsize,
 679                                   ret.dsize);
 680         unlock_lists(tdb, start, end, F_RDLCK);
 681         return ret;
 682 }
 683
 684 static int hash_add(struct tdb_context *tdb, uint64_t h, tdb_off_t off)
 685 {
 686         tdb_off_t i, hoff, len, num;
 687
 688         i = (h & ((1ULL << tdb->header.v.hash_bits) - 1));
 689         hoff = tdb->header.v.hash_off + i * sizeof(tdb_off_t);
 690         len = (1ULL << tdb->header.v.hash_bits) - i;
 691
 692         /* Look for next space. */
 693         num = tdb_find_zero_off(tdb, hoff, len);
 694         if (unlikely(num == len)) {
 695                 hoff = tdb->header.v.hash_off;
 696                 len = (1ULL << tdb->header.v.hash_bits);
 697                 num = tdb_find_zero_off(tdb, hoff, len);
 698                 if (i == len)
 699                         return -1;
 700         }
 701         /* FIXME: Encode extra hash bits! */
 702         return tdb_write_off(tdb, hoff + num * sizeof(tdb_off_t), off);
 703 }
 704
 705 static int unlink_used_record(struct tdb_context *tdb, tdb_off_t chain,
 706                               uint64_t *extra_locks)
 707 {
 708         tdb_off_t num, len, i, hoff;
 709
 710         /* FIXME: Maybe lock more in search?  Maybe don't lock if scan
 711          * finds none? */
 712 again:
 713         len = (1ULL << tdb->header.v.hash_bits) - (chain + 1);
 714         hoff = tdb->header.v.hash_off + (chain + 1) * sizeof(tdb_off_t);
 715         num = tdb_find_zero_off(tdb, hoff, len);
 716
 717         /* We want to lock the zero entry, too.  In the wrap case,
 718          * this locks one extra.  That's harmless. */
 719         num++;
 720
 721         for (i = chain + 1; i < chain + 1 + num; i++) {
 722                 if (tdb_lock_list(tdb, i, F_WRLCK, TDB_LOCK_WAIT) == -1) {
 723                         if (i != chain + 1)
 724                                 unlock_lists(tdb, chain + 1, i-1, F_WRLCK);
 725                         return -1;
 726                 }
 727         }
 728
 729         /* The wrap case: we need those locks out of order! */
 730         if (unlikely(num == len + 1)) {
 731                 *extra_locks = tdb_find_zero_off(tdb, tdb->header.v.hash_off,
 732                                                  1ULL << tdb->header.v.hash_bits);
 733                 (*extra_locks)++;
 734                 for (i = 0; i < *extra_locks; i++) {
 735                         if (tdb_lock_list(tdb, i, F_WRLCK, TDB_LOCK_NOWAIT)) {
 736                                 /* Failed.  Caller must lock in order. */
 737                                 if (i)
 738                                         unlock_lists(tdb, 0, i-1, F_WRLCK);
 739                                 unlock_lists(tdb, chain + 1, chain + num,
 740                                              F_WRLCK);
 741                                 return 1;
 742                         }
 743                 }
 744                 num += *extra_locks;
 745         }
 746
 747         /* Now we have the locks, be certain that offset is still 0! */
 748         hoff = tdb->header.v.hash_off
 749                 + (((chain + num) * sizeof(tdb_off_t))
 750                    & ((1ULL << tdb->header.v.hash_bits) - 1));
 751
 752         if (unlikely(tdb_read_off(tdb, hoff) != 0)) {
 753                 unlock_lists(tdb, chain + 1, chain + num, F_WRLCK);
 754                 goto again;
 755         }
 756
 757         /* OK, all locked.  Unlink first one. */
 758         hoff = tdb->header.v.hash_off + chain * sizeof(tdb_off_t);
 759         if (tdb_write_off(tdb, hoff, 0) == -1)
 760                 goto unlock_err;
 761
 762         /* Rehash the rest. */
 763         for (i = 1; i < num; i++) {
 764                 tdb_off_t off;
 765                 uint64_t h;
 766
 767                 hoff = tdb->header.v.hash_off
 768                         + (((chain + i) * sizeof(tdb_off_t))
 769                            & ((1ULL << tdb->header.v.hash_bits) - 1));
 770                 off = tdb_read_off(tdb, hoff);
 771                 if (unlikely(off == TDB_OFF_ERR))
 772                         goto unlock_err;
 773
 774                 /* Maybe use a bit to indicate it is in ideal place? */
 775                 h = hash_record(tdb, off);
 776                 /* Is it happy where it is? */
 777                 if ((h & ((1ULL << tdb->header.v.hash_bits)-1)) == (chain + i))
 778                         continue;
 779
 780                 /* Remove it. */
 781                 if (tdb_write_off(tdb, hoff, 0) == -1)
 782                         goto unlock_err;
 783
 784                 /* Rehash it. */
 785                 if (hash_add(tdb, h, off) == -1)
 786                         goto unlock_err;
 787         }
 788         unlock_lists(tdb, chain + 1, chain + num, F_WRLCK);
 789         return 0;
 790
 791 unlock_err:
 792         unlock_lists(tdb, chain + 1, chain + num, F_WRLCK);
 793         return -1;
 794 }
 795
 796 int tdb_delete(struct tdb_context *tdb, struct tdb_data key)
 797 {
 798         tdb_off_t off, start, end, room, extra_locks = 0;
 799         uint64_t h;
 800         int ret;
 801
 802         h = tdb_hash(tdb, key.dptr, key.dsize);
 803         off = find_bucket_and_lock(tdb, &key, h, &start, &end, &room, F_WRLCK);
 804         if (off == TDB_OFF_ERR)
 805                 return -1;
 806
 807         if (off == 0) {
 808                 unlock_lists(tdb, start, end, F_WRLCK);
 809                 tdb->ecode = TDB_ERR_NOEXIST;
 810                 return -1;
 811         }
 812
 813         ret = unlink_used_record(tdb, end, &extra_locks);
 814         if (unlikely(ret == 1)) {
 815                 unsigned int i;
 816
 817                 unlock_lists(tdb, start, end, F_WRLCK);
 818
 819                 /* We need extra locks at the start. */
 820                 for (i = 0; i < extra_locks; i++) {
 821                         if (tdb_lock_list(tdb, i, F_WRLCK, TDB_LOCK_WAIT)) {
 822                                 if (i)
 823                                         unlock_lists(tdb, 0, i-1, F_WRLCK);
 824                                 return -1;
 825                         }
 826                 }
 827                 /* Try again now we're holding more locks. */
 828                 ret = tdb_delete(tdb, key);
 829                 unlock_lists(tdb, 0, i, F_WRLCK);
 830                 return ret;
 831         }
 832         unlock_lists(tdb, start, end, F_WRLCK);
 833         return ret;
 834 }
 835
 836 int tdb_close(struct tdb_context *tdb)
 837 {
 838         struct tdb_context **i;
 839         int ret = 0;
 840
 841         /* FIXME:
 842         if (tdb->transaction) {
 843                 tdb_transaction_cancel(tdb);
 844         }
 845         */
 846         tdb_trace(tdb, "tdb_close");
 847
 848         if (tdb->map_ptr) {
 849                 if (tdb->flags & TDB_INTERNAL)
 850                         free(tdb->map_ptr);
 851                 else
 852                         tdb_munmap(tdb);
 853         }
 854         free((char *)tdb->name);
 855         if (tdb->fd != -1) {
 856                 ret = close(tdb->fd);
 857                 tdb->fd = -1;
 858         }
 859         free(tdb->lockrecs);
 860
 861         /* Remove from contexts list */
 862         for (i = &tdbs; *i; i = &(*i)->next) {
 863                 if (*i == tdb) {
 864                         *i = tdb->next;
 865                         break;
 866                 }
 867         }
 868
 869 #ifdef TDB_TRACE
 870         close(tdb->tracefd);
 871 #endif
 872         free(tdb);
 873
 874         return ret;
 875 }