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->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_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         if (!(tdb = (struct tdb_context *)calloc(1, sizeof *tdb))) {
 211                 /* Can't log this */
 212                 errno = ENOMEM;
 213                 goto fail;
 214         }
 215         tdb->fd = -1;
 216         tdb->name = NULL;
 217         tdb->map_ptr = NULL;
 218         tdb->flags = tdb_flags;
 219         tdb->log = null_log_fn;
 220         tdb->log_priv = NULL;
 221         tdb->khash = jenkins_hash;
 222         tdb->hash_priv = NULL;
 223         tdb_io_init(tdb);
 224
 225         /* FIXME */
 226         if (attr) {
 227                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 228                          "tdb_open: attributes not yet supported\n");
 229                 errno = EINVAL;
 230                 goto fail;
 231         }
 232
 233         if ((open_flags & O_ACCMODE) == O_WRONLY) {
 234                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 235                          "tdb_open: can't open tdb %s write-only\n", name);
 236                 errno = EINVAL;
 237                 goto fail;
 238         }
 239
 240         if ((open_flags & O_ACCMODE) == O_RDONLY) {
 241                 tdb->read_only = 1;
 242                 /* read only databases don't do locking */
 243                 tdb->flags |= TDB_NOLOCK;
 244         }
 245
 246         /* internal databases don't mmap or lock */
 247         if (tdb->flags & TDB_INTERNAL) {
 248                 tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
 249                 if (tdb_new_database(tdb) != 0) {
 250                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 251                                  "tdb_open: tdb_new_database failed!");
 252                         goto fail;
 253                 }
 254                 TEST_IT(tdb->flags & TDB_CONVERT);
 255                 tdb_convert(tdb, &tdb->header, sizeof(tdb->header));
 256                 goto internal;
 257         }
 258
 259         if ((tdb->fd = open(name, open_flags, mode)) == -1) {
 260                 tdb->log(tdb, TDB_DEBUG_WARNING, tdb->log_priv,
 261                          "tdb_open: could not open file %s: %s\n",
 262                          name, strerror(errno));
 263                 goto fail;      /* errno set by open(2) */
 264         }
 265
 266         /* on exec, don't inherit the fd */
 267         v = fcntl(tdb->fd, F_GETFD, 0);
 268         fcntl(tdb->fd, F_SETFD, v | FD_CLOEXEC);
 269
 270         /* ensure there is only one process initialising at once */
 271         if (tdb_lock_open(tdb) == -1) {
 272                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 273                          "tdb_open: failed to get open lock on %s: %s\n",
 274                          name, strerror(errno));
 275                 goto fail;      /* errno set by tdb_brlock */
 276         }
 277
 278         if (!tdb_pread_all(tdb->fd, &tdb->header, sizeof(tdb->header), 0)
 279             || strcmp(tdb->header.magic_food, TDB_MAGIC_FOOD) != 0) {
 280                 if (!(open_flags & O_CREAT) || tdb_new_database(tdb) == -1) {
 281                         if (errno == 0) {
 282                                 errno = EIO; /* ie bad format or something */
 283                         }
 284                         goto fail;
 285                 }
 286         } else if (tdb->header.version != TDB_VERSION) {
 287                 if (tdb->header.version == bswap_64(TDB_VERSION))
 288                         tdb->flags |= TDB_CONVERT;
 289                 else {
 290                         /* wrong version */
 291                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 292                                  "tdb_open: %s is unknown version 0x%llx\n",
 293                                  name, (long long)tdb->header.version);
 294                         errno = EIO;
 295                         goto fail;
 296                 }
 297         }
 298
 299         tdb_convert(tdb, &tdb->header, sizeof(tdb->header));
 300         hash_test = TDB_HASH_MAGIC;
 301         hash_test = tdb->khash(&hash_test, sizeof(hash_test),
 302                                tdb->header.hash_seed, tdb->hash_priv);
 303         if (tdb->header.hash_test != hash_test) {
 304                 /* wrong hash variant */
 305                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 306                          "tdb_open: %s uses a different hash function\n",
 307                          name);
 308                 errno = EIO;
 309                 goto fail;
 310         }
 311
 312         if (fstat(tdb->fd, &st) == -1)
 313                 goto fail;
 314
 315         /* Is it already in the open list?  If so, fail. */
 316         if (tdb_already_open(st.st_dev, st.st_ino)) {
 317                 /* FIXME */
 318                 tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 319                          "tdb_open: %s (%d,%d) is already open in this process\n",
 320                          name, (int)st.st_dev, (int)st.st_ino);
 321                 errno = EBUSY;
 322                 goto fail;
 323         }
 324
 325         tdb->name = strdup(name);
 326         if (!tdb->name) {
 327                 errno = ENOMEM;
 328                 goto fail;
 329         }
 330
 331         tdb->map_size = st.st_size;
 332         tdb->device = st.st_dev;
 333         tdb->inode = st.st_ino;
 334         tdb_io_init(tdb);
 335         tdb_mmap(tdb);
 336
 337  internal:
 338         /* Internal (memory-only) databases skip all the code above to
 339          * do with disk files, and resume here by releasing their
 340          * open lock and hooking into the active list. */
 341         tdb_unlock_open(tdb);
 342         tdb->last_zone = random_free_zone(tdb);
 343         tdb->next = tdbs;
 344         tdbs = tdb;
 345         return tdb;
 346
 347  fail:
 348         save_errno = errno;
 349
 350         if (!tdb)
 351                 return NULL;
 352
 353 #ifdef TDB_TRACE
 354         close(tdb->tracefd);
 355 #endif
 356         if (tdb->map_ptr) {
 357                 if (tdb->flags & TDB_INTERNAL) {
 358                         free(tdb->map_ptr);
 359                 } else
 360                         tdb_munmap(tdb);
 361         }
 362         free((char *)tdb->name);
 363         if (tdb->fd != -1)
 364                 if (close(tdb->fd) != 0)
 365                         tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
 366                                  "tdb_open: failed to close tdb->fd"
 367                                  " on error!\n");
 368         free(tdb);
 369         errno = save_errno;
 370         return NULL;
 371 }
 372
 373 static int tdb_key_compare(TDB_DATA key, TDB_DATA data, void *private_data)
 374 {
 375         return memcmp(data.dptr, key.dptr, data.dsize) == 0;
 376 }
 377
 378 static void unlock_lists(struct tdb_context *tdb,
 379                          uint64_t start, uint64_t end, int ltype)
 380 {
 381         do {
 382                 tdb_unlock_list(tdb, start, ltype);
 383                 start = (start + ((1ULL << tdb->header.v.hash_bits) - 1))
 384                         & ((1ULL << tdb->header.v.hash_bits) - 1);
 385         } while (start != end);
 386 }
 387
 388 /* FIXME: Return header copy? */
 389 /* Returns -1 or offset of entry (0 if not found).
 390  * Locks hash entried from *start to *end (where the entry was found). */
 391 static tdb_off_t find_bucket_and_lock(struct tdb_context *tdb,
 392                                       const struct tdb_data *key,
 393                                       uint64_t hash,
 394                                       uint64_t *start,
 395                                       uint64_t *end,
 396                                       uint64_t *room,
 397                                       int ltype)
 398 {
 399         uint64_t hextra;
 400         tdb_off_t off;
 401
 402         /* hash_bits might be out of date... */
 403 again:
 404         *start = *end = hash & ((1ULL << tdb->header.v.hash_bits) - 1);
 405         hextra = hash >> tdb->header.v.hash_bits;
 406
 407         /* FIXME: can we avoid locks for some fast paths? */
 408         if (tdb_lock_list(tdb, *end, ltype, TDB_LOCK_WAIT) == -1)
 409                 return TDB_OFF_ERR;
 410
 411         /* We only need to check this for first lock. */
 412         if (unlikely(update_header(tdb))) {
 413                 tdb_unlock_list(tdb, *end, ltype);
 414                 goto again;
 415         }
 416
 417         while ((off = tdb_read_off(tdb, tdb->header.v.hash_off
 418                                    + *end * sizeof(tdb_off_t)))
 419                != TDB_OFF_ERR) {
 420                 struct tdb_used_record pad, *r;
 421                 uint64_t keylen, next;
 422
 423                 /* Didn't find it? */
 424                 if (!off)
 425                         return 0;
 426
 427 #if 0 /* FIXME: Check other bits. */
 428                 unsigned int bits, bitmask, hoffextra;
 429                 /* Bottom three bits show how many extra hash bits. */
 430                 bits = (off & ((1 << TDB_EXTRA_HASHBITS_NUM) - 1)) + 1;
 431                 bitmask = (1 << bits)-1;
 432                 hoffextra = ((off >> TDB_EXTRA_HASHBITS_NUM) & bitmask);
 433                 if ((hextra & bitmask) != hoffextra)
 434                         goto lock_next;
 435 #endif
 436
 437                 r = tdb_get(tdb, off, &pad, sizeof(*r));
 438                 if (!r)
 439                         goto unlock_err;
 440
 441                 if (rec_magic(r) != TDB_MAGIC) {
 442                         tdb->ecode = TDB_ERR_CORRUPT;
 443                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 444                                  "find_bucket_and_lock: bad magic 0x%llx"
 445                                  " at offset %llu!\n",
 446                                  (long long)rec_magic(r), (long long)off);
 447                         goto unlock_err;
 448                 }
 449
 450                 /* FIXME: check extra bits in header! */
 451                 keylen = rec_key_length(r);
 452                 if (keylen != key->dsize)
 453                         goto lock_next;
 454
 455                 switch (tdb_parse_data(tdb, *key, off + sizeof(*r), key->dsize,
 456                                        tdb_key_compare, NULL)) {
 457                 case 1:
 458                         /* Match! */
 459                         *room = rec_data_length(r) + rec_extra_padding(r);
 460                         return off >> TDB_EXTRA_HASHBITS_NUM;
 461                 case 0:
 462                         break;
 463                 default:
 464                         goto unlock_err;
 465                 }
 466
 467         lock_next:
 468                 /* Lock next bucket. */
 469                 /* FIXME: We can deadlock if this wraps! */
 470                 next = (*end + 1) & ((1ULL << tdb->header.v.hash_bits) - 1);
 471                 if (next == *start) {
 472                         tdb->ecode = TDB_ERR_CORRUPT;
 473                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 474                                  "find_bucket_and_lock: full hash table!\n");
 475                         goto unlock_err;
 476                 }
 477                 if (tdb_lock_list(tdb, next, ltype, TDB_LOCK_WAIT) == -1)
 478                         goto unlock_err;
 479                 *end = next;
 480         }
 481
 482 unlock_err:
 483         TEST_IT(*end < *start);
 484         unlock_lists(tdb, *start, *end, ltype);
 485         return TDB_OFF_ERR;
 486 }
 487
 488 static int update_rec_hdr(struct tdb_context *tdb,
 489                           tdb_off_t off,
 490                           tdb_len_t keylen,
 491                           tdb_len_t datalen,
 492                           tdb_len_t room,
 493                           uint64_t h)
 494 {
 495         struct tdb_used_record rec;
 496
 497         if (set_header(tdb, &rec, keylen, datalen, room - datalen, h))
 498                 return -1;
 499
 500         return tdb_write_convert(tdb, off, &rec, sizeof(rec));
 501 }
 502
 503 /* If we fail, others will try after us. */
 504 static void enlarge_hash(struct tdb_context *tdb)
 505 {
 506         tdb_off_t newoff, i;
 507         uint64_t h, num = 1ULL << tdb->header.v.hash_bits;
 508         struct tdb_used_record pad, *r;
 509
 510         /* FIXME: We should do this without holding locks throughout. */
 511         if (tdb_allrecord_lock(tdb, F_WRLCK, TDB_LOCK_WAIT, false) == -1)
 512                 return;
 513
 514         if (unlikely(update_header(tdb))) {
 515                 /* Someone else enlarged for us?  Nothing to do. */
 516                 if ((1ULL << tdb->header.v.hash_bits) != num)
 517                         goto unlock;
 518         }
 519
 520         newoff = alloc(tdb, 0, num * 2, 0, false);
 521         if (unlikely(newoff == TDB_OFF_ERR))
 522                 goto unlock;
 523         if (unlikely(newoff == 0)) {
 524                 if (tdb_expand(tdb, 0, num * 2, false) == -1)
 525                         goto unlock;
 526                 newoff = alloc(tdb, 0, num * 2, 0, false);
 527                 if (newoff == TDB_OFF_ERR || newoff == 0)
 528                         goto unlock;
 529         }
 530
 531         /* FIXME: If the space before is empty, we know this is in its ideal
 532          * location.  We can steal a bit from the pointer to avoid rehash. */
 533         for (i = tdb_find_nonzero_off(tdb, tdb->header.v.hash_off, num);
 534              i < num;
 535              i += tdb_find_nonzero_off(tdb, tdb->header.v.hash_off
 536                                        + i*sizeof(tdb_off_t), num - i)) {
 537                 tdb_off_t off;
 538                 off = tdb_read_off(tdb, tdb->header.v.hash_off
 539                                    + i*sizeof(tdb_off_t));
 540                 if (unlikely(off == TDB_OFF_ERR))
 541                         goto unlock;
 542                 if (unlikely(!off)) {
 543                         tdb->ecode = TDB_ERR_CORRUPT;
 544                         tdb->log(tdb, TDB_DEBUG_FATAL, tdb->log_priv,
 545                                  "find_bucket_and_lock: zero hash bucket!\n");
 546                         goto unlock;
 547                 }
 548                 h = hash_record(tdb, off);
 549                 /* FIXME: Encode extra hash bits! */
 550                 if (tdb_write_off(tdb, newoff
 551                                   + (h & ((num * 2) - 1)) * sizeof(uint64_t),
 552                                   off) == -1)
 553                         goto unlock;
 554         }
 555
 556         /* Free up old hash. */
 557         r = tdb_get(tdb, tdb->header.v.hash_off, &pad, sizeof(*r));
 558         if (!r)
 559                 goto unlock;
 560         add_free_record(tdb, tdb->header.v.hash_off,
 561                         rec_data_length(r) + rec_extra_padding(r));
 562
 563         /* Now we write the modified header. */
 564         tdb->header.v.generation++;
 565         tdb->header.v.hash_bits++;
 566         tdb->header.v.hash_off = newoff;
 567         tdb_write_convert(tdb, offsetof(struct tdb_header, v),
 568                           &tdb->header.v, sizeof(tdb->header.v));
 569 unlock:
 570         tdb_allrecord_unlock(tdb, F_WRLCK);
 571 }
 572
 573 int tdb_store(struct tdb_context *tdb,
 574               struct tdb_data key, struct tdb_data dbuf, int flag)
 575 {
 576         tdb_off_t new_off, off, start, end, room;
 577         uint64_t h;
 578         bool growing = false;
 579
 580         h = tdb_hash(tdb, key.dptr, key.dsize);
 581         off = find_bucket_and_lock(tdb, &key, h, &start, &end, &room, F_WRLCK);
 582         if (off == TDB_OFF_ERR)
 583                 return -1;
 584
 585         /* Now we have lock on this hash bucket. */
 586         if (flag == TDB_INSERT) {
 587                 if (off) {
 588                         tdb->ecode = TDB_ERR_EXISTS;
 589                         goto fail;
 590                 }
 591         } else {
 592                 if (off) {
 593                         if (room >= key.dsize + dbuf.dsize) {
 594                                 new_off = off;
 595                                 if (update_rec_hdr(tdb, off,
 596                                                    key.dsize, dbuf.dsize,
 597                                                    room, h))
 598                                         goto fail;
 599                                 goto write;
 600                         }
 601                         /* FIXME: See if right record is free? */
 602                         /* Hint to allocator that we've realloced. */
 603                         growing = true;
 604                 } else {
 605                         if (flag == TDB_MODIFY) {
 606                                 /* if the record doesn't exist and we
 607                                    are in TDB_MODIFY mode then we should fail
 608                                    the store */
 609                                 tdb->ecode = TDB_ERR_NOEXIST;
 610                                 goto fail;
 611                         }
 612                 }
 613         }
 614
 615         /* Allocate a new record. */
 616         new_off = alloc(tdb, key.dsize, dbuf.dsize, h, growing);
 617         if (new_off == 0) {
 618                 unlock_lists(tdb, start, end, F_WRLCK);
 619                 /* Expand, then try again... */
 620                 if (tdb_expand(tdb, key.dsize, dbuf.dsize, growing) == -1)
 621                         return -1;
 622                 return tdb_store(tdb, key, dbuf, flag);
 623         }
 624
 625         /* We didn't like the existing one: remove it. */
 626         if (off) {
 627                 add_free_record(tdb, off, sizeof(struct tdb_used_record)
 628                                 + key.dsize + room);
 629         }
 630
 631 write:
 632         off = tdb->header.v.hash_off + end * sizeof(tdb_off_t);
 633         /* FIXME: Encode extra hash bits! */
 634         if (tdb_write_off(tdb, off, new_off) == -1)
 635                 goto fail;
 636
 637         off = new_off + sizeof(struct tdb_used_record);
 638         if (tdb->methods->write(tdb, off, key.dptr, key.dsize) == -1)
 639                 goto fail;
 640         off += key.dsize;
 641         if (tdb->methods->write(tdb, off, dbuf.dptr, dbuf.dsize) == -1)
 642                 goto fail;
 643
 644         /* FIXME: tdb_increment_seqnum(tdb); */
 645         unlock_lists(tdb, start, end, F_WRLCK);
 646
 647         /* By simple trial and error, this roughly approximates a 60%
 648          * full measure. */
 649         if (unlikely(end - start > 4 * tdb->header.v.hash_bits - 32))
 650                 enlarge_hash(tdb);
 651
 652         return 0;
 653
 654 fail:
 655         unlock_lists(tdb, start, end, F_WRLCK);
 656         return -1;
 657 }
 658
 659 struct tdb_data tdb_fetch(struct tdb_context *tdb, struct tdb_data key)
 660 {
 661         tdb_off_t off, start, end, room;
 662         uint64_t h;
 663         struct tdb_used_record pad, *r;
 664         struct tdb_data ret;
 665
 666         h = tdb_hash(tdb, key.dptr, key.dsize);
 667         off = find_bucket_and_lock(tdb, &key, h, &start, &end, &room, F_RDLCK);
 668         if (off == TDB_OFF_ERR)
 669                 return tdb_null;
 670
 671         if (!off) {
 672                 unlock_lists(tdb, start, end, F_RDLCK);
 673                 tdb->ecode = TDB_SUCCESS;
 674                 return tdb_null;
 675         }
 676
 677         r = tdb_get(tdb, off, &pad, sizeof(*r));
 678         if (!r) {
 679                 unlock_lists(tdb, start, end, F_RDLCK);
 680                 return tdb_null;
 681         }
 682
 683         ret.dsize = rec_data_length(r);
 684         ret.dptr = tdb_alloc_read(tdb, off + sizeof(*r) + key.dsize,
 685                                   ret.dsize);
 686         unlock_lists(tdb, start, end, F_RDLCK);
 687         return ret;
 688 }
 689
 690 static int hash_add(struct tdb_context *tdb, uint64_t h, tdb_off_t off)
 691 {
 692         tdb_off_t i, hoff, len, num;
 693
 694         i = (h & ((1ULL << tdb->header.v.hash_bits) - 1));
 695         hoff = tdb->header.v.hash_off + i * sizeof(tdb_off_t);
 696         len = (1ULL << tdb->header.v.hash_bits) - i;
 697
 698         /* Look for next space. */
 699         num = tdb_find_zero_off(tdb, hoff, len);
 700         if (unlikely(num == len)) {
 701                 hoff = tdb->header.v.hash_off;
 702                 len = (1ULL << tdb->header.v.hash_bits);
 703                 num = tdb_find_zero_off(tdb, hoff, len);
 704                 if (i == len)
 705                         return -1;
 706         }
 707         /* FIXME: Encode extra hash bits! */
 708         return tdb_write_off(tdb, hoff + num * sizeof(tdb_off_t), off);
 709 }
 710
 711 static int unlink_used_record(struct tdb_context *tdb, tdb_off_t chain,
 712                               uint64_t *extra_locks)
 713 {
 714         tdb_off_t num, len, i, hoff;
 715
 716         /* FIXME: Maybe lock more in search?  Maybe don't lock if scan
 717          * finds none? */
 718 again:
 719         len = (1ULL << tdb->header.v.hash_bits) - (chain + 1);
 720         hoff = tdb->header.v.hash_off + (chain + 1) * sizeof(tdb_off_t);
 721         num = tdb_find_zero_off(tdb, hoff, len);
 722
 723         /* We want to lock the zero entry, too.  In the wrap case,
 724          * this locks one extra.  That's harmless. */
 725         num++;
 726
 727         for (i = chain + 1; i < chain + 1 + num; i++) {
 728                 if (tdb_lock_list(tdb, i, F_WRLCK, TDB_LOCK_WAIT) == -1) {
 729                         if (i != chain + 1)
 730                                 unlock_lists(tdb, chain + 1, i-1, F_WRLCK);
 731                         return -1;
 732                 }
 733         }
 734
 735         /* The wrap case: we need those locks out of order! */
 736         if (unlikely(num == len + 1)) {
 737                 *extra_locks = tdb_find_zero_off(tdb, tdb->header.v.hash_off,
 738                                                  1ULL << tdb->header.v.hash_bits);
 739                 (*extra_locks)++;
 740                 for (i = 0; i < *extra_locks; i++) {
 741                         if (tdb_lock_list(tdb, i, F_WRLCK, TDB_LOCK_NOWAIT)) {
 742                                 /* Failed.  Caller must lock in order. */
 743                                 if (i)
 744                                         unlock_lists(tdb, 0, i-1, F_WRLCK);
 745                                 unlock_lists(tdb, chain + 1, chain + num,
 746                                              F_WRLCK);
 747                                 return 1;
 748                         }
 749                 }
 750                 num += *extra_locks;
 751         }
 752
 753         /* Now we have the locks, be certain that offset is still 0! */
 754         hoff = tdb->header.v.hash_off
 755                 + (((chain + num) * sizeof(tdb_off_t))
 756                    & ((1ULL << tdb->header.v.hash_bits) - 1));
 757
 758         if (unlikely(tdb_read_off(tdb, hoff) != 0)) {
 759                 unlock_lists(tdb, chain + 1, chain + num, F_WRLCK);
 760                 goto again;
 761         }
 762
 763         /* OK, all locked.  Unlink first one. */
 764         hoff = tdb->header.v.hash_off + chain * sizeof(tdb_off_t);
 765         if (tdb_write_off(tdb, hoff, 0) == -1)
 766                 goto unlock_err;
 767
 768         /* Rehash the rest. */
 769         for (i = 1; i < num; i++) {
 770                 tdb_off_t off;
 771                 uint64_t h;
 772
 773                 hoff = tdb->header.v.hash_off
 774                         + (((chain + i) * sizeof(tdb_off_t))
 775                            & ((1ULL << tdb->header.v.hash_bits) - 1));
 776                 off = tdb_read_off(tdb, hoff);
 777                 if (unlikely(off == TDB_OFF_ERR))
 778                         goto unlock_err;
 779
 780                 /* Maybe use a bit to indicate it is in ideal place? */
 781                 h = hash_record(tdb, off);
 782                 /* Is it happy where it is? */
 783                 if ((h & ((1ULL << tdb->header.v.hash_bits)-1)) == (chain + i))
 784                         continue;
 785
 786                 /* Remove it. */
 787                 if (tdb_write_off(tdb, hoff, 0) == -1)
 788                         goto unlock_err;
 789
 790                 /* Rehash it. */
 791                 if (hash_add(tdb, h, off) == -1)
 792                         goto unlock_err;
 793         }
 794         unlock_lists(tdb, chain + 1, chain + num, F_WRLCK);
 795         return 0;
 796
 797 unlock_err:
 798         unlock_lists(tdb, chain + 1, chain + num, F_WRLCK);
 799         return -1;
 800 }
 801
 802 int tdb_delete(struct tdb_context *tdb, struct tdb_data key)
 803 {
 804         tdb_off_t off, start, end, room, extra_locks = 0;
 805         uint64_t h;
 806         int ret;
 807
 808         h = tdb_hash(tdb, key.dptr, key.dsize);
 809         off = find_bucket_and_lock(tdb, &key, h, &start, &end, &room, F_WRLCK);
 810         if (off == TDB_OFF_ERR)
 811                 return -1;
 812
 813         if (off == 0) {
 814                 unlock_lists(tdb, start, end, F_WRLCK);
 815                 tdb->ecode = TDB_ERR_NOEXIST;
 816                 return -1;
 817         }
 818
 819         ret = unlink_used_record(tdb, end, &extra_locks);
 820         if (unlikely(ret == 1)) {
 821                 unsigned int i;
 822
 823                 unlock_lists(tdb, start, end, F_WRLCK);
 824
 825                 /* We need extra locks at the start. */
 826                 for (i = 0; i < extra_locks; i++) {
 827                         if (tdb_lock_list(tdb, i, F_WRLCK, TDB_LOCK_WAIT)) {
 828                                 if (i)
 829                                         unlock_lists(tdb, 0, i-1, F_WRLCK);
 830                                 return -1;
 831                         }
 832                 }
 833                 /* Try again now we're holding more locks. */
 834                 ret = tdb_delete(tdb, key);
 835                 unlock_lists(tdb, 0, i, F_WRLCK);
 836                 return ret;
 837         }
 838         unlock_lists(tdb, start, end, F_WRLCK);
 839         return ret;
 840 }
 841
 842 int tdb_close(struct tdb_context *tdb)
 843 {
 844         struct tdb_context **i;
 845         int ret = 0;
 846
 847         /* FIXME:
 848         if (tdb->transaction) {
 849                 tdb_transaction_cancel(tdb);
 850         }
 851         */
 852         tdb_trace(tdb, "tdb_close");
 853
 854         if (tdb->map_ptr) {
 855                 if (tdb->flags & TDB_INTERNAL)
 856                         free(tdb->map_ptr);
 857                 else
 858                         tdb_munmap(tdb);
 859         }
 860         free((char *)tdb->name);
 861         if (tdb->fd != -1) {
 862                 ret = close(tdb->fd);
 863                 tdb->fd = -1;
 864         }
 865         free(tdb->lockrecs);
 866
 867         /* Remove from contexts list */
 868         for (i = &tdbs; *i; i = &(*i)->next) {
 869                 if (*i == tdb) {
 870                         *i = tdb->next;
 871                         break;
 872                 }
 873         }
 874
 875 #ifdef TDB_TRACE
 876         close(tdb->tracefd);
 877 #endif
 878         free(tdb);
 879
 880         return ret;
 881 }