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

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