lib/tdb/common/open.c

   1  /*
   2    Unix SMB/CIFS implementation.
   3
   4    trivial database library
   5
   6    Copyright (C) Andrew Tridgell              1999-2005
   7    Copyright (C) Paul `Rusty' Russell              2000
   8    Copyright (C) Jeremy Allison                    2000-2003
   9
  10      ** NOTE! The following LGPL license applies to the tdb
  11      ** library. This does NOT imply that all of Samba is released
  12      ** under the LGPL
  13
  14    This library is free software; you can redistribute it and/or
  15    modify it under the terms of the GNU Lesser General Public
  16    License as published by the Free Software Foundation; either
  17    version 3 of the License, or (at your option) any later version.
  18
  19    This library is distributed in the hope that it will be useful,
  20    but WITHOUT ANY WARRANTY; without even the implied warranty of
  21    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  22    Lesser General Public License for more details.
  23
  24    You should have received a copy of the GNU Lesser General Public
  25    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  26 */
  27
  28 #include "tdb_private.h"
  29
  30 /* all contexts, to ensure no double-opens (fcntl locks don't nest!) */
  31 static struct tdb_context *tdbs = NULL;
  32
  33 /* We use two hashes to double-check they're using the right hash function. */
  34 void tdb_header_hash(struct tdb_context *tdb,
  35                      uint32_t *magic1_hash, uint32_t *magic2_hash)
  36 {
  37         TDB_DATA hash_key;
  38         uint32_t tdb_magic = TDB_MAGIC;
  39
  40         hash_key.dptr = discard_const_p(unsigned char, TDB_MAGIC_FOOD);
  41         hash_key.dsize = sizeof(TDB_MAGIC_FOOD);
  42         *magic1_hash = tdb->hash_fn(&hash_key);
  43
  44         hash_key.dptr = (unsigned char *)CONVERT(tdb_magic);
  45         hash_key.dsize = sizeof(tdb_magic);
  46         *magic2_hash = tdb->hash_fn(&hash_key);
  47
  48         /* Make sure at least one hash is non-zero! */
  49         if (*magic1_hash == 0 && *magic2_hash == 0)
  50                 *magic1_hash = 1;
  51 }
  52
  53 /* initialise a new database with a specified hash size */
  54 static int tdb_new_database(struct tdb_context *tdb, struct tdb_header *header,
  55                             int hash_size)
  56 {
  57         struct tdb_header *newdb;
  58         size_t size;
  59         int ret = -1;
  60
  61         /* We make it up in memory, then write it out if not internal */
  62         size = sizeof(struct tdb_header) + (hash_size+1)*sizeof(tdb_off_t);
  63         if (!(newdb = (struct tdb_header *)calloc(size, 1))) {
  64                 tdb->ecode = TDB_ERR_OOM;
  65                 return -1;
  66         }
  67
  68         /* Fill in the header */
  69         newdb->version = TDB_VERSION;
  70         newdb->hash_size = hash_size;
  71
  72         tdb_header_hash(tdb, &newdb->magic1_hash, &newdb->magic2_hash);
  73
  74         /* Make sure older tdbs (which don't check the magic hash fields)
  75          * will refuse to open this TDB. */
  76         if (tdb->flags & TDB_INCOMPATIBLE_HASH)
  77                 newdb->rwlocks = TDB_HASH_RWLOCK_MAGIC;
  78
  79         /*
  80          * We create a tdb with TDB_FEATURE_FLAG_MUTEX support,
  81          * the flag combination and runtime feature checks
  82          * are done by the caller already.
  83          */
  84         if (tdb->flags & TDB_MUTEX_LOCKING) {
  85                 newdb->feature_flags |= TDB_FEATURE_FLAG_MUTEX;
  86         }
  87
  88         /*
  89          * If we have any features we add the FEATURE_FLAG_MAGIC, overwriting the
  90          * TDB_HASH_RWLOCK_MAGIC above.
  91          */
  92         if (newdb->feature_flags != 0) {
  93                 newdb->rwlocks = TDB_FEATURE_FLAG_MAGIC;
  94         }
  95
  96         /*
  97          * It's required for some following code pathes
  98          * to have the fields on 'tdb' up-to-date.
  99          *
 100          * E.g. tdb_mutex_size() requires it
 101          */
 102         tdb->feature_flags = newdb->feature_flags;
 103         tdb->hash_size = newdb->hash_size;
 104
 105         if (tdb->flags & TDB_INTERNAL) {
 106                 tdb->map_size = size;
 107                 tdb->map_ptr = (char *)newdb;
 108                 memcpy(header, newdb, sizeof(*header));
 109                 /* Convert the `ondisk' version if asked. */
 110                 CONVERT(*newdb);
 111                 return 0;
 112         }
 113         if (lseek(tdb->fd, 0, SEEK_SET) == -1)
 114                 goto fail;
 115
 116         if (ftruncate(tdb->fd, 0) == -1)
 117                 goto fail;
 118
 119         if (newdb->feature_flags & TDB_FEATURE_FLAG_MUTEX) {
 120                 newdb->mutex_size = tdb_mutex_size(tdb);
 121                 tdb->hdr_ofs = newdb->mutex_size;
 122         }
 123
 124         /* This creates an endian-converted header, as if read from disk */
 125         CONVERT(*newdb);
 126         memcpy(header, newdb, sizeof(*header));
 127         /* Don't endian-convert the magic food! */
 128         memcpy(newdb->magic_food, TDB_MAGIC_FOOD, strlen(TDB_MAGIC_FOOD)+1);
 129
 130         if (!tdb_write_all(tdb->fd, newdb, size))
 131                 goto fail;
 132
 133         if (newdb->feature_flags & TDB_FEATURE_FLAG_MUTEX) {
 134
 135                 /*
 136                  * Now we init the mutex area
 137                  * followed by a second header.
 138                  */
 139
 140                 ret = ftruncate(
 141                         tdb->fd,
 142                         newdb->mutex_size + sizeof(struct tdb_header));
 143                 if (ret == -1) {
 144                         goto fail;
 145                 }
 146                 ret = tdb_mutex_init(tdb);
 147                 if (ret == -1) {
 148                         goto fail;
 149                 }
 150
 151                 /*
 152                  * Write a second header behind the mutexes. That's the area
 153                  * that will be mmapp'ed.
 154                  */
 155                 ret = lseek(tdb->fd, newdb->mutex_size, SEEK_SET);
 156                 if (ret == -1) {
 157                         goto fail;
 158                 }
 159                 if (!tdb_write_all(tdb->fd, newdb, size)) {
 160                         goto fail;
 161                 }
 162         }
 163
 164         ret = 0;
 165   fail:
 166         SAFE_FREE(newdb);
 167         return ret;
 168 }
 169
 170
 171
 172 static int tdb_already_open(dev_t device,
 173                             ino_t ino)
 174 {
 175         struct tdb_context *i;
 176
 177         for (i = tdbs; i; i = i->next) {
 178                 if (i->device == device && i->inode == ino) {
 179                         return 1;
 180                 }
 181         }
 182
 183         return 0;
 184 }
 185
 186 /* open the database, creating it if necessary
 187
 188    The open_flags and mode are passed straight to the open call on the
 189    database file. A flags value of O_WRONLY is invalid. The hash size
 190    is advisory, use zero for a default value.
 191
 192    Return is NULL on error, in which case errno is also set.  Don't
 193    try to call tdb_error or tdb_errname, just do strerror(errno).
 194
 195    @param name may be NULL for internal databases. */
 196 _PUBLIC_ struct tdb_context *tdb_open(const char *name, int hash_size, int tdb_flags,
 197                       int open_flags, mode_t mode)
 198 {
 199         return tdb_open_ex(name, hash_size, tdb_flags, open_flags, mode, NULL, NULL);
 200 }
 201
 202 /* a default logging function */
 203 static void null_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, const char *fmt, ...) PRINTF_ATTRIBUTE(3, 4);
 204 static void null_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, const char *fmt, ...)
 205 {
 206 }
 207
 208 static bool check_header_hash(struct tdb_context *tdb,
 209                               struct tdb_header *header,
 210                               bool default_hash, uint32_t *m1, uint32_t *m2)
 211 {
 212         tdb_header_hash(tdb, m1, m2);
 213         if (header->magic1_hash == *m1 &&
 214             header->magic2_hash == *m2) {
 215                 return true;
 216         }
 217
 218         /* If they explicitly set a hash, always respect it. */
 219         if (!default_hash)
 220                 return false;
 221
 222         /* Otherwise, try the other inbuilt hash. */
 223         if (tdb->hash_fn == tdb_old_hash)
 224                 tdb->hash_fn = tdb_jenkins_hash;
 225         else
 226                 tdb->hash_fn = tdb_old_hash;
 227         return check_header_hash(tdb, header, false, m1, m2);
 228 }
 229
 230 static bool tdb_mutex_open_ok(struct tdb_context *tdb,
 231                               const struct tdb_header *header)
 232 {
 233         if (tdb->flags & TDB_NOLOCK) {
 234                 /*
 235                  * We don't look at locks, so it does not matter to have a
 236                  * compatible mutex implementation. Allow the open.
 237                  */
 238                 return true;
 239         }
 240
 241         if (!(tdb->flags & TDB_MUTEX_LOCKING)) {
 242                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_mutex_open_ok[%s]: "
 243                          "Can use mutexes only with "
 244                          "MUTEX_LOCKING or NOLOCK\n",
 245                          tdb->name));
 246                 return false;
 247         }
 248
 249         if (tdb_mutex_size(tdb) != header->mutex_size) {
 250                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_mutex_open_ok[%s]: "
 251                          "Mutex size changed from %"PRIu32" to %zu\n.",
 252                          tdb->name,
 253                          header->mutex_size,
 254                          tdb_mutex_size(tdb)));
 255                 return false;
 256         }
 257
 258         return true;
 259 }
 260
 261 _PUBLIC_ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
 262                                 int open_flags, mode_t mode,
 263                                 const struct tdb_logging_context *log_ctx,
 264                                 tdb_hash_func hash_fn)
 265 {
 266         int orig_errno = errno;
 267         struct tdb_header header = {
 268                 .version = 0,
 269         };
 270         struct tdb_context *tdb;
 271         struct stat st;
 272         int rev = 0;
 273         bool locked = false;
 274         unsigned char *vp;
 275         uint32_t vertest;
 276         unsigned v;
 277         const char *hash_alg;
 278         uint32_t magic1, magic2;
 279         int ret;
 280
 281         if (!(tdb = (struct tdb_context *)calloc(1, sizeof *tdb))) {
 282                 /* Can't log this */
 283                 errno = ENOMEM;
 284                 goto fail;
 285         }
 286         tdb_io_init(tdb);
 287
 288         if (tdb_flags & TDB_INTERNAL) {
 289                 tdb_flags |= TDB_INCOMPATIBLE_HASH;
 290         }
 291         if (tdb_flags & TDB_MUTEX_LOCKING) {
 292                 tdb_flags |= TDB_INCOMPATIBLE_HASH;
 293         }
 294
 295         tdb->fd = -1;
 296 #ifdef TDB_TRACE
 297         tdb->tracefd = -1;
 298 #endif
 299         tdb->name = NULL;
 300         tdb->map_ptr = NULL;
 301         tdb->flags = tdb_flags;
 302         tdb->open_flags = open_flags;
 303         if (log_ctx) {
 304                 tdb->log = *log_ctx;
 305         } else {
 306                 tdb->log.log_fn = null_log_fn;
 307                 tdb->log.log_private = NULL;
 308         }
 309
 310         if (name == NULL && (tdb_flags & TDB_INTERNAL)) {
 311                 name = "__TDB_INTERNAL__";
 312         }
 313
 314         if (name == NULL) {
 315                 tdb->name = discard_const_p(char, "__NULL__");
 316                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: called with name == NULL\n"));
 317                 tdb->name = NULL;
 318                 errno = EINVAL;
 319                 goto fail;
 320         }
 321
 322         /* now make a copy of the name, as the caller memory might go away */
 323         if (!(tdb->name = (char *)strdup(name))) {
 324                 /*
 325                  * set the name as the given string, so that tdb_name() will
 326                  * work in case of an error.
 327                  */
 328                 tdb->name = discard_const_p(char, name);
 329                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: can't strdup(%s)\n",
 330                          name));
 331                 tdb->name = NULL;
 332                 errno = ENOMEM;
 333                 goto fail;
 334         }
 335
 336         if (hash_fn) {
 337                 tdb->hash_fn = hash_fn;
 338                 hash_alg = "the user defined";
 339         } else {
 340                 /* This controls what we use when creating a tdb. */
 341                 if (tdb->flags & TDB_INCOMPATIBLE_HASH) {
 342                         tdb->hash_fn = tdb_jenkins_hash;
 343                 } else {
 344                         tdb->hash_fn = tdb_old_hash;
 345                 }
 346                 hash_alg = "either default";
 347         }
 348
 349         /* cache the page size */
 350         tdb->page_size = getpagesize();
 351         if (tdb->page_size <= 0) {
 352                 tdb->page_size = 0x2000;
 353         }
 354
 355         tdb->max_dead_records = (tdb_flags & TDB_VOLATILE) ? 5 : 0;
 356
 357         if ((open_flags & O_ACCMODE) == O_WRONLY) {
 358                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: can't open tdb %s write-only\n",
 359                          name));
 360                 errno = EINVAL;
 361                 goto fail;
 362         }
 363
 364         if (hash_size == 0)
 365                 hash_size = DEFAULT_HASH_SIZE;
 366         if ((open_flags & O_ACCMODE) == O_RDONLY) {
 367                 tdb->read_only = 1;
 368                 /* read only databases don't do locking or clear if first */
 369                 tdb->flags |= TDB_NOLOCK;
 370                 tdb->flags &= ~(TDB_CLEAR_IF_FIRST|TDB_MUTEX_LOCKING);
 371         }
 372
 373         if ((tdb->flags & TDB_ALLOW_NESTING) &&
 374             (tdb->flags & TDB_DISALLOW_NESTING)) {
 375                 tdb->ecode = TDB_ERR_NESTING;
 376                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
 377                         "allow_nesting and disallow_nesting are not allowed together!"));
 378                 errno = EINVAL;
 379                 goto fail;
 380         }
 381
 382         if (tdb->flags & TDB_MUTEX_LOCKING) {
 383                 /*
 384                  * Here we catch bugs in the callers,
 385                  * the runtime check for existing tdb's comes later.
 386                  */
 387
 388                 if (tdb->flags & TDB_INTERNAL) {
 389                         TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
 390                                 "invalid flags for %s - TDB_MUTEX_LOCKING and "
 391                                 "TDB_INTERNAL are not allowed together\n", name));
 392                         errno = EINVAL;
 393                         goto fail;
 394                 }
 395
 396                 if (tdb->flags & TDB_NOMMAP) {
 397                         TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
 398                                 "invalid flags for %s - TDB_MUTEX_LOCKING and "
 399                                 "TDB_NOMMAP are not allowed together\n", name));
 400                         errno = EINVAL;
 401                         goto fail;
 402                 }
 403
 404                 if (tdb->read_only) {
 405                         TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
 406                                 "invalid flags for %s - TDB_MUTEX_LOCKING "
 407                                 "not allowed read only\n", name));
 408                         errno = EINVAL;
 409                         goto fail;
 410                 }
 411
 412                 /*
 413                  * The callers should have called
 414                  * tdb_runtime_check_for_robust_mutexes()
 415                  * before using TDB_MUTEX_LOCKING!
 416                  *
 417                  * This makes sure the caller understands
 418                  * that the locking may behave a bit differently
 419                  * than with pure fcntl locking. E.g. multiple
 420                  * read locks are not supported.
 421                  */
 422                 if (!tdb_runtime_check_for_robust_mutexes()) {
 423                         TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
 424                                 "invalid flags for %s - TDB_MUTEX_LOCKING "
 425                                 "requires support for robust_mutexes\n",
 426                                 name));
 427                         errno = ENOSYS;
 428                         goto fail;
 429                 }
 430         }
 431
 432         if (getenv("TDB_NO_FSYNC")) {
 433                 tdb->flags |= TDB_NOSYNC;
 434         }
 435
 436         /*
 437          * TDB_ALLOW_NESTING is the default behavior.
 438          * Note: this may change in future versions!
 439          */
 440         if (!(tdb->flags & TDB_DISALLOW_NESTING)) {
 441                 tdb->flags |= TDB_ALLOW_NESTING;
 442         }
 443
 444         /* internal databases don't mmap or lock, and start off cleared */
 445         if (tdb->flags & TDB_INTERNAL) {
 446                 tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
 447                 tdb->flags &= ~TDB_CLEAR_IF_FIRST;
 448                 if (tdb_new_database(tdb, &header, hash_size) != 0) {
 449                         TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: tdb_new_database failed!"));
 450                         goto fail;
 451                 }
 452                 tdb->hash_size = hash_size;
 453                 goto internal;
 454         }
 455
 456         if ((tdb->fd = open(name, open_flags, mode)) == -1) {
 457                 TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_open_ex: could not open file %s: %s\n",
 458                          name, strerror(errno)));
 459                 goto fail;      /* errno set by open(2) */
 460         }
 461
 462         /* on exec, don't inherit the fd */
 463         v = fcntl(tdb->fd, F_GETFD, 0);
 464         fcntl(tdb->fd, F_SETFD, v | FD_CLOEXEC);
 465
 466         /* ensure there is only one process initialising at once */
 467         if (tdb_nest_lock(tdb, OPEN_LOCK, F_WRLCK, TDB_LOCK_WAIT) == -1) {
 468                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to get open lock on %s: %s\n",
 469                          name, strerror(errno)));
 470                 goto fail;      /* errno set by tdb_brlock */
 471         }
 472
 473         /* we need to zero database if we are the only one with it open */
 474         if ((tdb_flags & TDB_CLEAR_IF_FIRST) &&
 475             (!tdb->read_only)) {
 476                 ret = tdb_nest_lock(tdb, ACTIVE_LOCK, F_WRLCK,
 477                                     TDB_LOCK_NOWAIT|TDB_LOCK_PROBE);
 478                 locked = (ret == 0);
 479
 480                 if (locked) {
 481                         ret = tdb_brlock(tdb, F_WRLCK, FREELIST_TOP, 0,
 482                                          TDB_LOCK_WAIT);
 483                         if (ret == -1) {
 484                                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
 485                                          "tdb_brlock failed for %s: %s\n",
 486                                          name, strerror(errno)));
 487                                 goto fail;
 488                         }
 489                         ret = tdb_new_database(tdb, &header, hash_size);
 490                         if (ret == -1) {
 491                                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
 492                                          "tdb_new_database failed for "
 493                                          "%s: %s\n", name, strerror(errno)));
 494                                 tdb_unlockall(tdb);
 495                                 goto fail;
 496                         }
 497                         ret = tdb_brunlock(tdb, F_WRLCK, FREELIST_TOP, 0);
 498                         if (ret == -1) {
 499                                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
 500                                          "tdb_unlockall failed for %s: %s\n",
 501                                          name, strerror(errno)));
 502                                 goto fail;
 503                         }
 504                         ret = lseek(tdb->fd, 0, SEEK_SET);
 505                         if (ret == -1) {
 506                                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
 507                                          "lseek failed for %s: %s\n",
 508                                          name, strerror(errno)));
 509                                 goto fail;
 510                         }
 511                 }
 512         }
 513
 514         errno = 0;
 515         if (read(tdb->fd, &header, sizeof(header)) != sizeof(header)
 516             || strcmp(header.magic_food, TDB_MAGIC_FOOD) != 0) {
 517                 if (!(open_flags & O_CREAT) ||
 518                     tdb_new_database(tdb, &header, hash_size) == -1) {
 519                         if (errno == 0) {
 520                                 errno = EIO; /* ie bad format or something */
 521                         }
 522                         goto fail;
 523                 }
 524                 rev = (tdb->flags & TDB_CONVERT);
 525         } else if (header.version != TDB_VERSION
 526                    && !(rev = (header.version==TDB_BYTEREV(TDB_VERSION)))) {
 527                 /* wrong version */
 528                 errno = EIO;
 529                 goto fail;
 530         }
 531         vp = (unsigned char *)&header.version;
 532         vertest = (((uint32_t)vp[0]) << 24) | (((uint32_t)vp[1]) << 16) |
 533                   (((uint32_t)vp[2]) << 8) | (uint32_t)vp[3];
 534         tdb->flags |= (vertest==TDB_VERSION) ? TDB_BIGENDIAN : 0;
 535         if (!rev)
 536                 tdb->flags &= ~TDB_CONVERT;
 537         else {
 538                 tdb->flags |= TDB_CONVERT;
 539                 tdb_convert(&header, sizeof(header));
 540         }
 541
 542         /*
 543          * We only use st.st_dev and st.st_ino from the raw fstat()
 544          * call, everything else needs to use tdb_fstat() in order
 545          * to skip tdb->hdr_ofs!
 546          */
 547         if (fstat(tdb->fd, &st) == -1) {
 548                 goto fail;
 549         }
 550         tdb->device = st.st_dev;
 551         tdb->inode = st.st_ino;
 552         ZERO_STRUCT(st);
 553
 554         if (header.rwlocks != 0 &&
 555             header.rwlocks != TDB_FEATURE_FLAG_MAGIC &&
 556             header.rwlocks != TDB_HASH_RWLOCK_MAGIC) {
 557                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: spinlocks no longer supported\n"));
 558                 errno = ENOSYS;
 559                 goto fail;
 560         }
 561
 562         if (header.hash_size == 0) {
 563                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: invalid database: 0 hash_size\n"));
 564                 errno = ENOSYS;
 565                 goto fail;
 566         }
 567
 568         tdb->hash_size = header.hash_size;
 569
 570         if (header.rwlocks == TDB_FEATURE_FLAG_MAGIC) {
 571                 tdb->feature_flags = header.feature_flags;
 572         }
 573
 574         if (tdb->feature_flags & ~TDB_SUPPORTED_FEATURE_FLAGS) {
 575                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: unsupported "
 576                          "features in tdb %s: 0x%08x (supported: 0x%08x)\n",
 577                          name, (unsigned)tdb->feature_flags,
 578                          (unsigned)TDB_SUPPORTED_FEATURE_FLAGS));
 579                 errno = ENOSYS;
 580                 goto fail;
 581         }
 582
 583         if (tdb->feature_flags & TDB_FEATURE_FLAG_MUTEX) {
 584                 if (!tdb_mutex_open_ok(tdb, &header)) {
 585                         errno = EINVAL;
 586                         goto fail;
 587                 }
 588
 589                 /*
 590                  * We need to remember the hdr_ofs
 591                  * also for the TDB_NOLOCK case
 592                  * if the current library doesn't support
 593                  * mutex locking.
 594                  */
 595                 tdb->hdr_ofs = header.mutex_size;
 596
 597                 if ((!(tdb_flags & TDB_CLEAR_IF_FIRST)) && (!tdb->read_only)) {
 598                         /*
 599                          * Open an existing mutexed tdb, but without
 600                          * CLEAR_IF_FIRST. We need to initialize the
 601                          * mutex array and keep the CLEAR_IF_FIRST
 602                          * lock locked.
 603                          */
 604                         ret = tdb_nest_lock(tdb, ACTIVE_LOCK, F_WRLCK,
 605                                             TDB_LOCK_NOWAIT|TDB_LOCK_PROBE);
 606                         locked = (ret == 0);
 607
 608                         if (locked) {
 609                                 ret = tdb_mutex_init(tdb);
 610                                 if (ret == -1) {
 611                                         TDB_LOG((tdb,
 612                                                  TDB_DEBUG_FATAL,
 613                                                  "tdb_open_ex: tdb_mutex_init "
 614                                                  "failed for ""%s: %s\n",
 615                                                  name, strerror(errno)));
 616                                         goto fail;
 617                                 }
 618                         }
 619                 }
 620         }
 621
 622         if ((header.magic1_hash == 0) && (header.magic2_hash == 0)) {
 623                 /* older TDB without magic hash references */
 624                 tdb->hash_fn = tdb_old_hash;
 625         } else if (!check_header_hash(tdb, &header, !hash_fn,
 626                                       &magic1, &magic2)) {
 627                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
 628                          "%s was not created with %s hash function we are using\n"
 629                          "magic1_hash[0x%08X %s 0x%08X] "
 630                          "magic2_hash[0x%08X %s 0x%08X]\n",
 631                          name, hash_alg,
 632                          header.magic1_hash,
 633                          (header.magic1_hash == magic1) ? "==" : "!=",
 634                          magic1,
 635                          header.magic2_hash,
 636                          (header.magic2_hash == magic2) ? "==" : "!=",
 637                          magic2));
 638                 errno = EINVAL;
 639                 goto fail;
 640         }
 641
 642         /* Is it already in the open list?  If so, fail. */
 643         if (tdb_already_open(tdb->device, tdb->inode)) {
 644                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
 645                          "%s (%d,%d) is already open in this process\n",
 646                          name, (int)tdb->device, (int)tdb->inode));
 647                 errno = EBUSY;
 648                 goto fail;
 649         }
 650
 651         /*
 652          * We had tdb_mmap(tdb) here before,
 653          * but we need to use tdb_fstat(),
 654          * which is triggered from tdb_oob() before calling tdb_mmap().
 655          * As this skips tdb->hdr_ofs.
 656          */
 657         tdb->map_size = 0;
 658         ret = tdb->methods->tdb_oob(tdb, 0, 1, 0);
 659         if (ret == -1) {
 660                 errno = EIO;
 661                 goto fail;
 662         }
 663
 664         if (tdb->feature_flags & TDB_FEATURE_FLAG_MUTEX) {
 665                 if (!(tdb->flags & TDB_NOLOCK)) {
 666                         ret = tdb_mutex_mmap(tdb);
 667                         if (ret != 0) {
 668                                 goto fail;
 669                         }
 670                 }
 671         }
 672
 673         if (tdb->hash_size > UINT32_MAX/4) {
 674                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
 675                          "hash size %"PRIu32" too large\n", tdb->hash_size));
 676                 errno = EINVAL;
 677                 goto fail;
 678         }
 679
 680         ret = tdb->methods->tdb_oob(tdb, FREELIST_TOP, 4*tdb->hash_size, 1);
 681         if (ret == -1) {
 682                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
 683                          "hash size %"PRIu32" does not fit\n", tdb->hash_size));
 684                 errno = EINVAL;
 685                 goto fail;
 686         }
 687
 688         if (locked) {
 689                 if (tdb_nest_unlock(tdb, ACTIVE_LOCK, F_WRLCK, false) == -1) {
 690                         TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: "
 691                                  "failed to release ACTIVE_LOCK on %s: %s\n",
 692                                  name, strerror(errno)));
 693                         goto fail;
 694                 }
 695
 696
 697         }
 698
 699         if (locked || (tdb_flags & TDB_CLEAR_IF_FIRST)) {
 700                 /*
 701                  * We always need to do this if the CLEAR_IF_FIRST
 702                  * flag is set, even if we didn't get the initial
 703                  * exclusive lock as we need to let all other users
 704                  * know we're using it.
 705                  */
 706
 707                 ret = tdb_nest_lock(tdb, ACTIVE_LOCK, F_RDLCK, TDB_LOCK_WAIT);
 708                 if (ret == -1) {
 709                         goto fail;
 710                 }
 711         }
 712
 713         /* if needed, run recovery */
 714         if (tdb_transaction_recover(tdb) == -1) {
 715                 goto fail;
 716         }
 717
 718 #ifdef TDB_TRACE
 719         {
 720                 char tracefile[strlen(name) + 32];
 721
 722                 snprintf(tracefile, sizeof(tracefile),
 723                          "%s.trace.%li", name, (long)getpid());
 724                 tdb->tracefd = open(tracefile, O_WRONLY|O_CREAT|O_EXCL, 0600);
 725                 if (tdb->tracefd >= 0) {
 726                         tdb_enable_seqnum(tdb);
 727                         tdb_trace_open(tdb, "tdb_open", hash_size, tdb_flags,
 728                                        open_flags);
 729                 } else
 730                         TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to open trace file %s!\n", tracefile));
 731         }
 732 #endif
 733
 734  internal:
 735         /* Internal (memory-only) databases skip all the code above to
 736          * do with disk files, and resume here by releasing their
 737          * open lock and hooking into the active list. */
 738         if (tdb_nest_unlock(tdb, OPEN_LOCK, F_WRLCK, false) == -1) {
 739                 goto fail;
 740         }
 741         tdb->next = tdbs;
 742         tdbs = tdb;
 743         errno = orig_errno;
 744         return tdb;
 745
 746  fail:
 747         { int save_errno = errno;
 748
 749         if (!tdb)
 750                 return NULL;
 751
 752 #ifdef TDB_TRACE
 753         close(tdb->tracefd);
 754 #endif
 755         if (tdb->map_ptr) {
 756                 if (tdb->flags & TDB_INTERNAL)
 757                         SAFE_FREE(tdb->map_ptr);
 758                 else
 759                         tdb_munmap(tdb);
 760         }
 761         if (tdb->fd != -1)
 762                 if (close(tdb->fd) != 0)
 763                         TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: failed to close tdb->fd on error!\n"));
 764         SAFE_FREE(tdb->lockrecs);
 765         SAFE_FREE(tdb->name);
 766         SAFE_FREE(tdb);
 767         errno = save_errno;
 768         return NULL;
 769         }
 770 }
 771
 772 /*
 773  * Set the maximum number of dead records per hash chain
 774  */
 775
 776 _PUBLIC_ void tdb_set_max_dead(struct tdb_context *tdb, int max_dead)
 777 {
 778         tdb->max_dead_records = max_dead;
 779 }
 780
 781 /**
 782  * Close a database.
 783  *
 784  * @returns -1 for error; 0 for success.
 785  **/
 786 _PUBLIC_ int tdb_close(struct tdb_context *tdb)
 787 {
 788         struct tdb_context **i;
 789         int ret = 0;
 790
 791         if (tdb->transaction) {
 792                 tdb_transaction_cancel(tdb);
 793         }
 794         tdb_trace(tdb, "tdb_close");
 795
 796         if (tdb->map_ptr) {
 797                 if (tdb->flags & TDB_INTERNAL)
 798                         SAFE_FREE(tdb->map_ptr);
 799                 else
 800                         tdb_munmap(tdb);
 801         }
 802
 803         tdb_mutex_munmap(tdb);
 804
 805         SAFE_FREE(tdb->name);
 806         if (tdb->fd != -1) {
 807                 ret = close(tdb->fd);
 808                 tdb->fd = -1;
 809         }
 810         SAFE_FREE(tdb->lockrecs);
 811
 812         /* Remove from contexts list */
 813         for (i = &tdbs; *i; i = &(*i)->next) {
 814                 if (*i == tdb) {
 815                         *i = tdb->next;
 816                         break;
 817                 }
 818         }
 819
 820 #ifdef TDB_TRACE
 821         close(tdb->tracefd);
 822 #endif
 823         memset(tdb, 0, sizeof(*tdb));
 824         SAFE_FREE(tdb);
 825
 826         return ret;
 827 }
 828
 829 /* register a loging function */
 830 _PUBLIC_ void tdb_set_logging_function(struct tdb_context *tdb,
 831                                        const struct tdb_logging_context *log_ctx)
 832 {
 833         tdb->log = *log_ctx;
 834 }
 835
 836 _PUBLIC_ void *tdb_get_logging_private(struct tdb_context *tdb)
 837 {
 838         return tdb->log.log_private;
 839 }
 840
 841 static int tdb_reopen_internal(struct tdb_context *tdb, bool active_lock)
 842 {
 843 #if !defined(LIBREPLACE_PREAD_NOT_REPLACED) || \
 844         !defined(LIBREPLACE_PWRITE_NOT_REPLACED)
 845         struct stat st;
 846 #endif
 847
 848         if (tdb->flags & TDB_INTERNAL) {
 849                 return 0; /* Nothing to do. */
 850         }
 851
 852         if (tdb_have_extra_locks(tdb)) {
 853                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_reopen: reopen not allowed with locks held\n"));
 854                 goto fail;
 855         }
 856
 857         if (tdb->transaction != 0) {
 858                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_reopen: reopen not allowed inside a transaction\n"));
 859                 goto fail;
 860         }
 861
 862 /* If we have real pread & pwrite, we can skip reopen. */
 863 #if !defined(LIBREPLACE_PREAD_NOT_REPLACED) || \
 864         !defined(LIBREPLACE_PWRITE_NOT_REPLACED)
 865         if (tdb_munmap(tdb) != 0) {
 866                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: munmap failed (%s)\n", strerror(errno)));
 867                 goto fail;
 868         }
 869         if (close(tdb->fd) != 0)
 870                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: WARNING closing tdb->fd failed!\n"));
 871         tdb->fd = open(tdb->name, tdb->open_flags & ~(O_CREAT|O_TRUNC), 0);
 872         if (tdb->fd == -1) {
 873                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: open failed (%s)\n", strerror(errno)));
 874                 goto fail;
 875         }
 876         /*
 877          * We only use st.st_dev and st.st_ino from the raw fstat()
 878          * call, everything else needs to use tdb_fstat() in order
 879          * to skip tdb->hdr_ofs!
 880          */
 881         if (fstat(tdb->fd, &st) != 0) {
 882                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: fstat failed (%s)\n", strerror(errno)));
 883                 goto fail;
 884         }
 885         if (st.st_ino != tdb->inode || st.st_dev != tdb->device) {
 886                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: file dev/inode has changed!\n"));
 887                 goto fail;
 888         }
 889         ZERO_STRUCT(st);
 890
 891         /*
 892          * We had tdb_mmap(tdb) here before,
 893          * but we need to use tdb_fstat(),
 894          * which is triggered from tdb_oob() before calling tdb_mmap().
 895          * As this skips tdb->hdr_ofs.
 896          */
 897         tdb->map_size = 0;
 898         if (tdb->methods->tdb_oob(tdb, 0, 1, 0) != 0) {
 899                 goto fail;
 900         }
 901 #endif /* fake pread or pwrite */
 902
 903         /* We may still think we hold the active lock. */
 904         tdb->num_lockrecs = 0;
 905         SAFE_FREE(tdb->lockrecs);
 906         tdb->lockrecs_array_length = 0;
 907
 908         if (active_lock && tdb_nest_lock(tdb, ACTIVE_LOCK, F_RDLCK, TDB_LOCK_WAIT) == -1) {
 909                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_reopen: failed to obtain active lock\n"));
 910                 goto fail;
 911         }
 912
 913         return 0;
 914
 915 fail:
 916         tdb_close(tdb);
 917         return -1;
 918 }
 919
 920 /* reopen a tdb - this can be used after a fork to ensure that we have an independent
 921    seek pointer from our parent and to re-establish locks */
 922 _PUBLIC_ int tdb_reopen(struct tdb_context *tdb)
 923 {
 924         bool active_lock;
 925         active_lock = (tdb->flags & (TDB_CLEAR_IF_FIRST|TDB_MUTEX_LOCKING));
 926
 927         return tdb_reopen_internal(tdb, active_lock);
 928 }
 929
 930 /* reopen all tdb's */
 931 _PUBLIC_ int tdb_reopen_all(int parent_longlived)
 932 {
 933         struct tdb_context *tdb;
 934
 935         for (tdb=tdbs; tdb; tdb = tdb->next) {
 936                 bool active_lock;
 937
 938                 active_lock =
 939                         (tdb->flags & (TDB_CLEAR_IF_FIRST|TDB_MUTEX_LOCKING));
 940
 941                 /*
 942                  * If the parent is longlived (ie. a
 943                  * parent daemon architecture), we know
 944                  * it will keep it's active lock on a
 945                  * tdb opened with CLEAR_IF_FIRST. Thus
 946                  * for child processes we don't have to
 947                  * add an active lock. This is essential
 948                  * to improve performance on systems that
 949                  * keep POSIX locks as a non-scalable data
 950                  * structure in the kernel.
 951                  */
 952                 if (parent_longlived) {
 953                         /* Ensure no clear-if-first. */
 954                         active_lock = false;
 955                 }
 956
 957                 if (tdb_reopen_internal(tdb, active_lock) != 0)
 958                         return -1;
 959         }
 960
 961         return 0;
 962 }