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

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