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         newdb.hdr.seqnum = 0;
 111         memset(newdb.hdr.reserved, 0, sizeof(newdb.hdr.reserved));
 112         /* Initial hashes are empty. */
 113         memset(newdb.hdr.hashtable, 0, sizeof(newdb.hdr.hashtable));
 114
 115         /* Free is empty. */
 116         newdb.hdr.free_table = offsetof(struct new_database, ftable);
 117         memset(&newdb.ftable, 0, sizeof(newdb.ftable));
 118         ecode = set_header(NULL, &newdb.ftable.hdr, TDB_FTABLE_MAGIC, 0,
 119                            sizeof(newdb.ftable) - sizeof(newdb.ftable.hdr),
 120                            sizeof(newdb.ftable) - sizeof(newdb.ftable.hdr),
 121                            0);
 122         if (ecode != TDB_SUCCESS) {
 123                 return ecode;
 124         }
 125
 126         /* Magic food */
 127         memset(newdb.hdr.magic_food, 0, sizeof(newdb.hdr.magic_food));
 128         strcpy(newdb.hdr.magic_food, TDB_MAGIC_FOOD);
 129
 130         /* This creates an endian-converted database, as if read from disk */
 131         magic_len = sizeof(newdb.hdr.magic_food);
 132         tdb_convert(tdb,
 133                     (char *)&newdb.hdr + magic_len, sizeof(newdb) - magic_len);
 134
 135         *hdr = newdb.hdr;
 136
 137         if (tdb->flags & TDB_INTERNAL) {
 138                 tdb->file->map_size = sizeof(newdb);
 139                 tdb->file->map_ptr = malloc(tdb->file->map_size);
 140                 if (!tdb->file->map_ptr) {
 141                         return tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
 142                                           "tdb_new_database:"
 143                                           " failed to allocate");
 144                 }
 145                 memcpy(tdb->file->map_ptr, &newdb, tdb->file->map_size);
 146                 return TDB_SUCCESS;
 147         }
 148         if (lseek(tdb->file->fd, 0, SEEK_SET) == -1) {
 149                 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 150                                   "tdb_new_database:"
 151                                   " failed to seek: %s", strerror(errno));
 152         }
 153
 154         if (ftruncate(tdb->file->fd, 0) == -1) {
 155                 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 156                                   "tdb_new_database:"
 157                                   " failed to truncate: %s", strerror(errno));
 158         }
 159
 160         rlen = write(tdb->file->fd, &newdb, sizeof(newdb));
 161         if (rlen != sizeof(newdb)) {
 162                 if (rlen >= 0)
 163                         errno = ENOSPC;
 164                 return tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 165                                   "tdb_new_database: %zi writing header: %s",
 166                                   rlen, strerror(errno));
 167         }
 168         return TDB_SUCCESS;
 169 }
 170
 171 static enum TDB_ERROR tdb_new_file(struct tdb_context *tdb)
 172 {
 173         tdb->file = malloc(sizeof(*tdb->file));
 174         if (!tdb->file)
 175                 return tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
 176                                   "tdb_open: could alloc tdb_file structure");
 177         tdb->file->num_lockrecs = 0;
 178         tdb->file->lockrecs = NULL;
 179         tdb->file->allrecord_lock.count = 0;
 180         tdb->file->refcnt = 1;
 181         return TDB_SUCCESS;
 182 }
 183
 184 struct tdb_context *tdb_open(const char *name, int tdb_flags,
 185                              int open_flags, mode_t mode,
 186                              union tdb_attribute *attr)
 187 {
 188         struct tdb_context *tdb;
 189         struct stat st;
 190         int saved_errno = 0;
 191         uint64_t hash_test;
 192         unsigned v;
 193         ssize_t rlen;
 194         struct tdb_header hdr;
 195         struct tdb_attribute_seed *seed = NULL;
 196         tdb_bool_err berr;
 197         enum TDB_ERROR ecode;
 198
 199         tdb = malloc(sizeof(*tdb));
 200         if (!tdb) {
 201                 /* Can't log this */
 202                 errno = ENOMEM;
 203                 return NULL;
 204         }
 205         tdb->name = NULL;
 206         tdb->direct_access = 0;
 207         tdb->flags = tdb_flags;
 208         tdb->logfn = NULL;
 209         tdb->transaction = NULL;
 210         tdb->stats = NULL;
 211         tdb->access = NULL;
 212         tdb->last_error = TDB_SUCCESS;
 213         tdb->file = NULL;
 214         tdb_hash_init(tdb);
 215         tdb_io_init(tdb);
 216
 217         while (attr) {
 218                 switch (attr->base.attr) {
 219                 case TDB_ATTRIBUTE_LOG:
 220                         tdb->logfn = attr->log.log_fn;
 221                         tdb->log_private = attr->log.log_private;
 222                         break;
 223                 case TDB_ATTRIBUTE_HASH:
 224                         tdb->khash = attr->hash.hash_fn;
 225                         tdb->hash_priv = attr->hash.hash_private;
 226                         break;
 227                 case TDB_ATTRIBUTE_SEED:
 228                         seed = &attr->seed;
 229                         break;
 230                 case TDB_ATTRIBUTE_STATS:
 231                         tdb->stats = &attr->stats;
 232                         /* They have stats we don't know about?  Tell them. */
 233                         if (tdb->stats->size > sizeof(attr->stats))
 234                                 tdb->stats->size = sizeof(attr->stats);
 235                         break;
 236                 default:
 237                         ecode = tdb_logerr(tdb, TDB_ERR_EINVAL,
 238                                            TDB_LOG_USE_ERROR,
 239                                            "tdb_open:"
 240                                            " unknown attribute type %u",
 241                                            attr->base.attr);
 242                         goto fail;
 243                 }
 244                 attr = attr->base.next;
 245         }
 246
 247         if (tdb_flags & ~(TDB_INTERNAL | TDB_NOLOCK | TDB_NOMMAP | TDB_CONVERT
 248                           | TDB_NOSYNC | TDB_SEQNUM)) {
 249                 ecode = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
 250                                    "tdb_open: unknown flags %u", tdb_flags);
 251                 goto fail;
 252         }
 253
 254         if ((open_flags & O_ACCMODE) == O_WRONLY) {
 255                 ecode = tdb_logerr(tdb, TDB_ERR_EINVAL, TDB_LOG_USE_ERROR,
 256                                    "tdb_open: can't open tdb %s write-only",
 257                                    name);
 258                 goto fail;
 259         }
 260
 261         if ((open_flags & O_ACCMODE) == O_RDONLY) {
 262                 tdb->read_only = true;
 263                 tdb->mmap_flags = PROT_READ;
 264         } else {
 265                 tdb->read_only = false;
 266                 tdb->mmap_flags = PROT_READ | PROT_WRITE;
 267         }
 268
 269         /* internal databases don't need any of the rest. */
 270         if (tdb->flags & TDB_INTERNAL) {
 271                 tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
 272                 ecode = tdb_new_file(tdb);
 273                 if (ecode != TDB_SUCCESS) {
 274                         goto fail;
 275                 }
 276                 tdb->file->fd = -1;
 277                 ecode = tdb_new_database(tdb, seed, &hdr);
 278                 if (ecode != TDB_SUCCESS) {
 279                         goto fail;
 280                 }
 281                 if (name) {
 282                         tdb->name = strdup(name);
 283                         if (!tdb->name) {
 284                                 ecode = tdb_logerr(tdb, TDB_ERR_OOM,
 285                                                    TDB_LOG_ERROR,
 286                                                    "tdb_open: failed to"
 287                                                    " allocate name");
 288                                 goto fail;
 289                         }
 290                 }
 291                 tdb_convert(tdb, &hdr.hash_seed, sizeof(hdr.hash_seed));
 292                 tdb->hash_seed = hdr.hash_seed;
 293                 tdb_ftable_init(tdb);
 294                 return tdb;
 295         }
 296
 297         if (stat(name, &st) != -1)
 298                 tdb->file = find_file(st.st_dev, st.st_ino);
 299
 300         if (!tdb->file) {
 301                 int fd;
 302
 303                 if ((fd = open(name, open_flags, mode)) == -1) {
 304                         /* errno set by open(2) */
 305                         saved_errno = errno;
 306                         tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 307                                    "tdb_open: could not open file %s: %s",
 308                                    name, strerror(errno));
 309                         goto fail_errno;
 310                 }
 311
 312                 /* on exec, don't inherit the fd */
 313                 v = fcntl(fd, F_GETFD, 0);
 314                 fcntl(fd, F_SETFD, v | FD_CLOEXEC);
 315
 316                 if (fstat(fd, &st) == -1) {
 317                         saved_errno = errno;
 318                         tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 319                                    "tdb_open: could not stat open %s: %s",
 320                                    name, strerror(errno));
 321                         goto fail_errno;
 322                 }
 323
 324                 ecode = tdb_new_file(tdb);
 325                 if (ecode != TDB_SUCCESS)
 326                         goto fail;
 327
 328                 tdb->file->next = files;
 329                 tdb->file->fd = fd;
 330                 tdb->file->device = st.st_dev;
 331                 tdb->file->inode = st.st_ino;
 332                 tdb->file->map_ptr = NULL;
 333                 tdb->file->map_size = sizeof(struct tdb_header);
 334         }
 335
 336         /* ensure there is only one process initialising at once */
 337         ecode = tdb_lock_open(tdb, TDB_LOCK_WAIT|TDB_LOCK_NOCHECK);
 338         if (ecode != TDB_SUCCESS) {
 339                 goto fail;
 340         }
 341
 342         /* If they used O_TRUNC, read will return 0. */
 343         rlen = pread(tdb->file->fd, &hdr, sizeof(hdr), 0);
 344         if (rlen == 0 && (open_flags & O_CREAT)) {
 345                 ecode = tdb_new_database(tdb, seed, &hdr);
 346                 if (ecode != TDB_SUCCESS) {
 347                         goto fail;
 348                 }
 349         } else if (rlen < 0) {
 350                 ecode = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 351                                    "tdb_open: error %s reading %s",
 352                                    strerror(errno), name);
 353                 goto fail;
 354         } else if (rlen < sizeof(hdr)
 355                    || strcmp(hdr.magic_food, TDB_MAGIC_FOOD) != 0) {
 356                 ecode = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 357                                    "tdb_open: %s is not a tdb file", name);
 358                 goto fail;
 359         }
 360
 361         if (hdr.version != TDB_VERSION) {
 362                 if (hdr.version == bswap_64(TDB_VERSION))
 363                         tdb->flags |= TDB_CONVERT;
 364                 else {
 365                         /* wrong version */
 366                         ecode = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 367                                            "tdb_open:"
 368                                            " %s is unknown version 0x%llx",
 369                                            name, (long long)hdr.version);
 370                         goto fail;
 371                 }
 372         }
 373
 374         tdb_convert(tdb, &hdr, sizeof(hdr));
 375         tdb->hash_seed = hdr.hash_seed;
 376         hash_test = TDB_HASH_MAGIC;
 377         hash_test = tdb_hash(tdb, &hash_test, sizeof(hash_test));
 378         if (hdr.hash_test != hash_test) {
 379                 /* wrong hash variant */
 380                 ecode = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 381                                    "tdb_open:"
 382                                    " %s uses a different hash function",
 383                                    name);
 384                 goto fail;
 385         }
 386
 387         tdb->name = strdup(name);
 388         if (!tdb->name) {
 389                 ecode = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
 390                                    "tdb_open: failed to allocate name");
 391                 goto fail;
 392         }
 393
 394         /* Clear any features we don't understand. */
 395         if ((open_flags & O_ACCMODE) != O_RDONLY) {
 396                 hdr.features_used &= TDB_FEATURE_MASK;
 397                 if (tdb_write_convert(tdb, offsetof(struct tdb_header,
 398                                                     features_used),
 399                                       &hdr.features_used,
 400                                       sizeof(hdr.features_used)) == -1)
 401                         goto fail;
 402         }
 403
 404         tdb_unlock_open(tdb);
 405
 406         /* This make sure we have current map_size and mmap. */
 407         tdb->methods->oob(tdb, tdb->file->map_size + 1, true);
 408
 409         /* Now it's fully formed, recover if necessary. */
 410         berr = tdb_needs_recovery(tdb);
 411         if (unlikely(berr != false)) {
 412                 if (berr < 0) {
 413                         ecode = berr;
 414                         goto fail;
 415                 }
 416                 ecode = tdb_lock_and_recover(tdb);
 417                 if (ecode != TDB_SUCCESS) {
 418                         goto fail;
 419                 }
 420         }
 421
 422         ecode = tdb_ftable_init(tdb);
 423         if (ecode != TDB_SUCCESS) {
 424                 goto fail;
 425         }
 426
 427         /* Add to linked list if we're new. */
 428         if (tdb->file->refcnt == 1)
 429                 files = tdb->file;
 430         return tdb;
 431
 432  fail:
 433         /* Map ecode to some logical errno. */
 434         switch (ecode) {
 435         case TDB_ERR_CORRUPT:
 436         case TDB_ERR_IO:
 437                 saved_errno = EIO;
 438                 break;
 439         case TDB_ERR_LOCK:
 440                 saved_errno = EWOULDBLOCK;
 441                 break;
 442         case TDB_ERR_OOM:
 443                 saved_errno = ENOMEM;
 444                 break;
 445         case TDB_ERR_EINVAL:
 446                 saved_errno = EINVAL;
 447                 break;
 448         default:
 449                 saved_errno = EINVAL;
 450                 break;
 451         }
 452
 453 fail_errno:
 454 #ifdef TDB_TRACE
 455         close(tdb->tracefd);
 456 #endif
 457         free(cast_const(char *, tdb->name));
 458         if (tdb->file) {
 459                 tdb_unlock_all(tdb);
 460                 if (--tdb->file->refcnt == 0) {
 461                         assert(tdb->file->num_lockrecs == 0);
 462                         if (tdb->file->map_ptr) {
 463                                 if (tdb->flags & TDB_INTERNAL) {
 464                                         free(tdb->file->map_ptr);
 465                                 } else
 466                                         tdb_munmap(tdb->file);
 467                         }
 468                         if (close(tdb->file->fd) != 0)
 469                                 tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 470                                            "tdb_open: failed to close tdb fd"
 471                                            " on error: %s", strerror(errno));
 472                         free(tdb->file->lockrecs);
 473                         free(tdb->file);
 474                 }
 475         }
 476
 477         free(tdb);
 478         errno = saved_errno;
 479         return NULL;
 480 }
 481
 482 int tdb_close(struct tdb_context *tdb)
 483 {
 484         int ret = 0;
 485
 486         tdb_trace(tdb, "tdb_close");
 487
 488         if (tdb->transaction) {
 489                 tdb_transaction_cancel(tdb);
 490         }
 491
 492         if (tdb->file->map_ptr) {
 493                 if (tdb->flags & TDB_INTERNAL)
 494                         free(tdb->file->map_ptr);
 495                 else
 496                         tdb_munmap(tdb->file);
 497         }
 498         free(cast_const(char *, tdb->name));
 499         if (tdb->file) {
 500                 struct tdb_file **i;
 501
 502                 tdb_unlock_all(tdb);
 503                 if (--tdb->file->refcnt == 0) {
 504                         ret = close(tdb->file->fd);
 505
 506                         /* Remove from files list */
 507                         for (i = &files; *i; i = &(*i)->next) {
 508                                 if (*i == tdb->file) {
 509                                         *i = tdb->file->next;
 510                                         break;
 511                                 }
 512                         }
 513                         free(tdb->file->lockrecs);
 514                         free(tdb->file);
 515                 }
 516         }
 517
 518 #ifdef TDB_TRACE
 519         close(tdb->tracefd);
 520 #endif
 521         free(tdb);
 522
 523         return ret;
 524 }