git.ozlabs.org Git - ccan/blob - ccan/tdb2/open.c

   1 #include "private.h"
   2 #include <assert.h>
   3
   4 /* all lock info, to detect double-opens (fcntl file don't nest!) */
   5 static struct tdb_file *files = NULL;
   6
   7 static struct tdb_file *find_file(dev_t device, ino_t ino)
   8 {
   9         struct tdb_file *i;
  10
  11         for (i = files; i; i = i->next) {
  12                 if (i->device == device && i->inode == ino) {
  13                         i->refcnt++;
  14                         break;
  15                 }
  16         }
  17         return i;
  18 }
  19
  20 static bool read_all(int fd, void *buf, size_t len)
  21 {
  22         while (len) {
  23                 ssize_t ret;
  24                 ret = read(fd, buf, len);
  25                 if (ret < 0)
  26                         return false;
  27                 if (ret == 0) {
  28                         /* ETOOSHORT? */
  29                         errno = EWOULDBLOCK;
  30                         return false;
  31                 }
  32                 buf = (char *)buf + ret;
  33                 len -= ret;
  34         }
  35         return true;
  36 }
  37
  38 static uint64_t random_number(struct tdb_context *tdb)
  39 {
  40         int fd;
  41         uint64_t ret = 0;
  42         struct timeval now;
  43
  44         fd = open("/dev/urandom", O_RDONLY);
  45         if (fd >= 0) {
  46                 if (read_all(fd, &ret, sizeof(ret))) {
  47                         close(fd);
  48                         return ret;
  49                 }
  50                 close(fd);
  51         }
  52         /* FIXME: Untested!  Based on Wikipedia protocol description! */
  53         fd = open("/dev/egd-pool", O_RDWR);
  54         if (fd >= 0) {
  55                 /* Command is 1, next byte is size we want to read. */
  56                 char cmd[2] = { 1, sizeof(uint64_t) };
  57                 if (write(fd, cmd, sizeof(cmd)) == sizeof(cmd)) {
  58                         char reply[1 + sizeof(uint64_t)];
  59                         int r = read(fd, reply, sizeof(reply));
  60                         if (r > 1) {
  61                                 /* Copy at least some bytes. */
  62                                 memcpy(&ret, reply+1, r - 1);
  63                                 if (reply[0] == sizeof(uint64_t)
  64                                     && r == sizeof(reply)) {
  65                                         close(fd);
  66                                         return ret;
  67                                 }
  68                         }
  69                 }
  70                 close(fd);
  71         }
  72
  73         /* Fallback: pid and time. */
  74         gettimeofday(&now, NULL);
  75         ret = getpid() * 100132289ULL + now.tv_sec * 1000000ULL + now.tv_usec;
  76         tdb_logerr(tdb, TDB_SUCCESS, TDB_LOG_WARNING,
  77                    "tdb_open: random from getpid and time");
  78         return ret;
  79 }
  80
  81 struct new_database {
  82         struct tdb_header hdr;
  83         struct tdb_freetable ftable;
  84 };
  85
  86 /* initialise a new database */
  87 static enum TDB_ERROR tdb_new_database(struct tdb_context *tdb,
  88                                        struct tdb_attribute_seed *seed,
  89                                        struct tdb_header *hdr)
  90 {
  91         /* We make it up in memory, then write it out if not internal */
  92         struct new_database newdb;
  93         unsigned int magic_len;
  94         ssize_t rlen;
  95         enum TDB_ERROR ecode;
  96
  97         /* Fill in the header */
  98         newdb.hdr.version = TDB_VERSION;
  99         if (seed)
 100                 newdb.hdr.hash_seed = seed->seed;
 101         else
 102                 newdb.hdr.hash_seed = random_number(tdb);
 103         newdb.hdr.hash_test = TDB_HASH_MAGIC;
 104         newdb.hdr.hash_test = tdb->khash(&newdb.hdr.hash_test,
 105                                          sizeof(newdb.hdr.hash_test),
 106                                          newdb.hdr.hash_seed,
 107                                          tdb->hash_priv);
 108         newdb.hdr.recovery = 0;
 109         newdb.hdr.features_used = newdb.hdr.features_offered = TDB_FEATURE_MASK;
 110         memset(newdb.hdr.reserved, 0, sizeof(newdb.hdr.reserved));
 111         /* Initial hashes are empty. */
 112         memset(newdb.hdr.hashtable, 0, sizeof(newdb.hdr.hashtable));
 113
 114         /* Free is empty. */
 115         newdb.hdr.free_table = offsetof(struct new_database, ftable);
 116         memset(&newdb.ftable, 0, sizeof(newdb.ftable));
 117         ecode = set_header(NULL, &newdb.ftable.hdr, TDB_FTABLE_MAGIC, 0,
 118                            sizeof(newdb.ftable) - sizeof(newdb.ftable.hdr),
 119                            sizeof(newdb.ftable) - sizeof(newdb.ftable.hdr),
 120                            0);
 121         if (ecode != TDB_SUCCESS) {
 122                 return ecode;
 123         }
 124
 125         /* Magic food */
 126         memset(newdb.hdr.magic_food, 0, sizeof(newdb.hdr.magic_food));
 127         strcpy(newdb.hdr.magic_food, TDB_MAGIC_FOOD);
 128
 129         /* This creates an endian-converted database, as if read from disk */
 130         magic_len = sizeof(newdb.hdr.magic_food);
 131         tdb_convert(tdb,
 132                     (char *)&newdb.hdr + magic_len, sizeof(newdb) - magic_len);
 133
 134         *hdr = newdb.hdr;
 135
 136         if (tdb->flags & TDB_INTERNAL) {
 137                 tdb->file->map_size = sizeof(newdb);
 138                 tdb->file->map_ptr = malloc(tdb->file->map_size);
 139                 if (!tdb->file->map_ptr) {
 140                         return tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
 141                                           "tdb_new_database:"
 142                                           " failed to allocate");
 143                 }
 144                 memcpy(tdb->file->map_ptr, &newdb, tdb->file->map_size);
 145                 return TDB_SUCCESS;
 146         }
 147         if (lseek(tdb->file->fd, 0, SEEK_SET) == -1) {
 148                 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 149                                   "tdb_new_database:"
 150                                   " failed to seek: %s", strerror(errno));
 151         }
 152
 153         if (ftruncate(tdb->file->fd, 0) == -1) {
 154                 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 155                                   "tdb_new_database:"
 156                                   " failed to truncate: %s", strerror(errno));
 157         }
 158
 159         rlen = write(tdb->file->fd, &newdb, sizeof(newdb));
 160         if (rlen != sizeof(newdb)) {
 161                 if (rlen >= 0)
 162                         errno = ENOSPC;
 163                 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 164                                   "tdb_new_database: %zi writing header: %s",
 165                                   rlen, strerror(errno));
 166         }
 167         return TDB_SUCCESS;
 168 }
 169
 170 static enum TDB_ERROR tdb_new_file(struct tdb_context *tdb)
 171 {
 172         tdb->file = malloc(sizeof(*tdb->file));
 173         if (!tdb->file)
 174                 return tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
 175                                   "tdb_open: could alloc tdb_file structure");
 176         tdb->file->num_lockrecs = 0;
 177         tdb->file->lockrecs = NULL;
 178         tdb->file->allrecord_lock.count = 0;
 179         tdb->file->refcnt = 1;
 180         return TDB_SUCCESS;
 181 }
 182
 183 struct tdb_context *tdb_open(const char *name, int tdb_flags,
 184                              int open_flags, mode_t mode,
 185                              union tdb_attribute *attr)
 186 {
 187         struct tdb_context *tdb;
 188         struct stat st;
 189         int saved_errno = 0;
 190         uint64_t hash_test;
 191         unsigned v;
 192         ssize_t rlen;
 193         struct tdb_header hdr;
 194         struct tdb_attribute_seed *seed = NULL;
 195         tdb_bool_err berr;
 196         enum TDB_ERROR ecode;
 197
 198         tdb = malloc(sizeof(*tdb));
 199         if (!tdb) {
 200                 /* Can't log this */
 201                 errno = ENOMEM;
 202                 return NULL;
 203         }
 204         tdb->name = NULL;
 205         tdb->direct_access = 0;
 206         tdb->flags = tdb_flags;
 207         tdb->logfn = NULL;
 208         tdb->transaction = NULL;
 209         tdb->stats = NULL;
 210         tdb->access = NULL;
 211         tdb->file = NULL;
 212         tdb_hash_init(tdb);
 213         tdb_io_init(tdb);
 214
 215         while (attr) {
 216                 switch (attr->base.attr) {
 217                 case TDB_ATTRIBUTE_LOG:
 218                         tdb->logfn = attr->log.log_fn;
 219                         tdb->log_private = attr->log.log_private;
 220                         break;
 221                 case TDB_ATTRIBUTE_HASH:
 222                         tdb->khash = attr->hash.hash_fn;
 223                         tdb->hash_priv = attr->hash.hash_private;
 224                         break;
 225                 case TDB_ATTRIBUTE_SEED:
 226                         seed = &attr->seed;
 227                         break;
 228                 case TDB_ATTRIBUTE_STATS:
 229                         tdb->stats = &attr->stats;
 230                         /* They have stats we don't know about?  Tell them. */
 231                         if (tdb->stats->size > sizeof(attr->stats))
 232                                 tdb->stats->size = sizeof(attr->stats);
 233                         break;
 234                 default:
 235                         ecode = tdb_logerr(tdb, TDB_ERR_EINVAL,
 236                                            TDB_LOG_USE_ERROR,
 237                                            "tdb_open:"
 238                                            " unknown attribute type %u",
 239                                            attr->base.attr);
 240                         goto fail;
 241                 }
 242                 attr = attr->base.next;
 243         }
 244
 245         if (tdb_flags & ~(TDB_INTERNAL | TDB_NOLOCK | TDB_NOMMAP | TDB_CONVERT
 246                           | TDB_NOSYNC)) {
 247                 ecode = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
 248                                    "tdb_open: unknown flags %u", tdb_flags);
 249                 goto fail;
 250         }
 251
 252         if ((open_flags & O_ACCMODE) == O_WRONLY) {
 253                 ecode = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
 254                                    "tdb_open: can't open tdb %s write-only",
 255                                    name);
 256                 goto fail;
 257         }
 258
 259         if ((open_flags & O_ACCMODE) == O_RDONLY) {
 260                 tdb->read_only = true;
 261                 tdb->mmap_flags = PROT_READ;
 262         } else {
 263                 tdb->read_only = false;
 264                 tdb->mmap_flags = PROT_READ | PROT_WRITE;
 265         }
 266
 267         /* internal databases don't need any of the rest. */
 268         if (tdb->flags & TDB_INTERNAL) {
 269                 tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
 270                 ecode = tdb_new_file(tdb);
 271                 if (ecode != TDB_SUCCESS) {
 272                         goto fail;
 273                 }
 274                 tdb->file->fd = -1;
 275                 ecode = tdb_new_database(tdb, seed, &hdr);
 276                 if (ecode != TDB_SUCCESS) {
 277                         goto fail;
 278                 }
 279                 tdb_convert(tdb, &hdr.hash_seed, sizeof(hdr.hash_seed));
 280                 tdb->hash_seed = hdr.hash_seed;
 281                 tdb_ftable_init(tdb);
 282                 return tdb;
 283         }
 284
 285         if (stat(name, &st) != -1)
 286                 tdb->file = find_file(st.st_dev, st.st_ino);
 287
 288         if (!tdb->file) {
 289                 int fd;
 290
 291                 if ((fd = open(name, open_flags, mode)) == -1) {
 292                         /* errno set by open(2) */
 293                         saved_errno = errno;
 294                         tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 295                                    "tdb_open: could not open file %s: %s",
 296                                    name, strerror(errno));
 297                         goto fail_errno;
 298                 }
 299
 300                 /* on exec, don't inherit the fd */
 301                 v = fcntl(fd, F_GETFD, 0);
 302                 fcntl(fd, F_SETFD, v | FD_CLOEXEC);
 303
 304                 if (fstat(fd, &st) == -1) {
 305                         saved_errno = errno;
 306                         tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 307                                    "tdb_open: could not stat open %s: %s",
 308                                    name, strerror(errno));
 309                         goto fail_errno;
 310                 }
 311
 312                 ecode = tdb_new_file(tdb);
 313                 if (ecode != TDB_SUCCESS)
 314                         goto fail;
 315
 316                 tdb->file->next = files;
 317                 tdb->file->fd = fd;
 318                 tdb->file->device = st.st_dev;
 319                 tdb->file->inode = st.st_ino;
 320                 tdb->file->map_ptr = NULL;
 321                 tdb->file->map_size = sizeof(struct tdb_header);
 322         }
 323
 324         /* ensure there is only one process initialising at once */
 325         ecode = tdb_lock_open(tdb, TDB_LOCK_WAIT|TDB_LOCK_NOCHECK);
 326         if (ecode != TDB_SUCCESS) {
 327                 goto fail;
 328         }
 329
 330         /* If they used O_TRUNC, read will return 0. */
 331         rlen = pread(tdb->file->fd, &hdr, sizeof(hdr), 0);
 332         if (rlen == 0 && (open_flags & O_CREAT)) {
 333                 ecode = tdb_new_database(tdb, seed, &hdr);
 334                 if (ecode != TDB_SUCCESS) {
 335                         goto fail;
 336                 }
 337         } else if (rlen < 0) {
 338                 ecode = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 339                                    "tdb_open: error %s reading %s",
 340                                    strerror(errno), name);
 341                 goto fail;
 342         } else if (rlen < sizeof(hdr)
 343                    || strcmp(hdr.magic_food, TDB_MAGIC_FOOD) != 0) {
 344                 ecode = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 345                                    "tdb_open: %s is not a tdb file", name);
 346                 goto fail;
 347         }
 348
 349         if (hdr.version != TDB_VERSION) {
 350                 if (hdr.version == bswap_64(TDB_VERSION))
 351                         tdb->flags |= TDB_CONVERT;
 352                 else {
 353                         /* wrong version */
 354                         ecode = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 355                                            "tdb_open:"
 356                                            " %s is unknown version 0x%llx",
 357                                            name, (long long)hdr.version);
 358                         goto fail;
 359                 }
 360         }
 361
 362         tdb_convert(tdb, &hdr, sizeof(hdr));
 363         tdb->hash_seed = hdr.hash_seed;
 364         hash_test = TDB_HASH_MAGIC;
 365         hash_test = tdb_hash(tdb, &hash_test, sizeof(hash_test));
 366         if (hdr.hash_test != hash_test) {
 367                 /* wrong hash variant */
 368                 ecode = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 369                                    "tdb_open:"
 370                                    " %s uses a different hash function",
 371                                    name);
 372                 goto fail;
 373         }
 374
 375         tdb->name = strdup(name);
 376         if (!tdb->name) {
 377                 ecode = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
 378                                    "tdb_open: failed to allocate name");
 379                 goto fail;
 380         }
 381
 382         /* Clear any features we don't understand. */
 383         if ((open_flags & O_ACCMODE) != O_RDONLY) {
 384                 hdr.features_used &= TDB_FEATURE_MASK;
 385                 if (tdb_write_convert(tdb, offsetof(struct tdb_header,
 386                                                     features_used),
 387                                       &hdr.features_used,
 388                                       sizeof(hdr.features_used)) == -1)
 389                         goto fail;
 390         }
 391
 392         tdb_unlock_open(tdb);
 393
 394         /* This make sure we have current map_size and mmap. */
 395         tdb->methods->oob(tdb, tdb->file->map_size + 1, true);
 396
 397         /* Now it's fully formed, recover if necessary. */
 398         berr = tdb_needs_recovery(tdb);
 399         if (unlikely(berr != false)) {
 400                 if (berr < 0) {
 401                         ecode = berr;
 402                         goto fail;
 403                 }
 404                 ecode = tdb_lock_and_recover(tdb);
 405                 if (ecode != TDB_SUCCESS) {
 406                         goto fail;
 407                 }
 408         }
 409
 410         ecode = tdb_ftable_init(tdb);
 411         if (ecode != TDB_SUCCESS) {
 412                 goto fail;
 413         }
 414
 415         /* Add to linked list if we're new. */
 416         if (tdb->file->refcnt == 1)
 417                 files = tdb->file;
 418         return tdb;
 419
 420  fail:
 421         /* Map ecode to some logical errno. */
 422         switch (ecode) {
 423         case TDB_ERR_CORRUPT:
 424         case TDB_ERR_IO:
 425                 saved_errno = EIO;
 426                 break;
 427         case TDB_ERR_LOCK:
 428                 saved_errno = EWOULDBLOCK;
 429                 break;
 430         case TDB_ERR_OOM:
 431                 saved_errno = ENOMEM;
 432                 break;
 433         case TDB_ERR_EINVAL:
 434                 saved_errno = EINVAL;
 435                 break;
 436         default:
 437                 saved_errno = EINVAL;
 438                 break;
 439         }
 440
 441 fail_errno:
 442 #ifdef TDB_TRACE
 443         close(tdb->tracefd);
 444 #endif
 445         free((char *)tdb->name);
 446         if (tdb->file) {
 447                 tdb_unlock_all(tdb);
 448                 if (--tdb->file->refcnt == 0) {
 449                         assert(tdb->file->num_lockrecs == 0);
 450                         if (tdb->file->map_ptr) {
 451                                 if (tdb->flags & TDB_INTERNAL) {
 452                                         free(tdb->file->map_ptr);
 453                                 } else
 454                                         tdb_munmap(tdb->file);
 455                         }
 456                         if (close(tdb->file->fd) != 0)
 457                                 tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 458                                            "tdb_open: failed to close tdb fd"
 459                                            " on error: %s", strerror(errno));
 460                         free(tdb->file->lockrecs);
 461                         free(tdb->file);
 462                 }
 463         }
 464
 465         free(tdb);
 466         errno = saved_errno;
 467         return NULL;
 468 }
 469
 470 int tdb_close(struct tdb_context *tdb)
 471 {
 472         int ret = 0;
 473
 474         tdb_trace(tdb, "tdb_close");
 475
 476         if (tdb->transaction) {
 477                 tdb_transaction_cancel(tdb);
 478         }
 479
 480         if (tdb->file->map_ptr) {
 481                 if (tdb->flags & TDB_INTERNAL)
 482                         free(tdb->file->map_ptr);
 483                 else
 484                         tdb_munmap(tdb->file);
 485         }
 486         free((char *)tdb->name);
 487         if (tdb->file) {
 488                 struct tdb_file **i;
 489
 490                 tdb_unlock_all(tdb);
 491                 if (--tdb->file->refcnt == 0) {
 492                         ret = close(tdb->file->fd);
 493
 494                         /* Remove from files list */
 495                         for (i = &files; *i; i = &(*i)->next) {
 496                                 if (*i == tdb->file) {
 497                                         *i = tdb->file->next;
 498                                         break;
 499                                 }
 500                         }
 501                         free(tdb->file->lockrecs);
 502                         free(tdb->file);
 503                 }
 504         }
 505
 506 #ifdef TDB_TRACE
 507         close(tdb->tracefd);
 508 #endif
 509         free(tdb);
 510
 511         return ret;
 512 }