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

   1  /*
   2    Trivial Database 2: fetch, store and misc routines.
   3    Copyright (C) Rusty Russell 2010
   4
   5    This library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 3 of the License, or (at your option) any later version.
   9
  10    This library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  17 */
  18 #include "private.h"
  19 #include <ccan/asprintf/asprintf.h>
  20 #include <stdarg.h>
  21
  22 static enum TDB_ERROR update_rec_hdr(struct tdb_context *tdb,
  23                                      tdb_off_t off,
  24                                      tdb_len_t keylen,
  25                                      tdb_len_t datalen,
  26                                      struct tdb_used_record *rec,
  27                                      uint64_t h)
  28 {
  29         uint64_t dataroom = rec_data_length(rec) + rec_extra_padding(rec);
  30         enum TDB_ERROR ecode;
  31
  32         ecode = set_header(tdb, rec, TDB_USED_MAGIC, keylen, datalen,
  33                            keylen + dataroom, h);
  34         if (ecode == TDB_SUCCESS) {
  35                 ecode = tdb_write_convert(tdb, off, rec, sizeof(*rec));
  36         }
  37         return ecode;
  38 }
  39
  40 static enum TDB_ERROR replace_data(struct tdb_context *tdb,
  41                                    struct hash_info *h,
  42                                    struct tdb_data key, struct tdb_data dbuf,
  43                                    tdb_off_t old_off, tdb_len_t old_room,
  44                                    bool growing)
  45 {
  46         tdb_off_t new_off;
  47         enum TDB_ERROR ecode;
  48
  49         /* Allocate a new record. */
  50         new_off = alloc(tdb, key.dsize, dbuf.dsize, h->h, TDB_USED_MAGIC,
  51                         growing);
  52         if (TDB_OFF_IS_ERR(new_off)) {
  53                 return new_off;
  54         }
  55
  56         /* We didn't like the existing one: remove it. */
  57         if (old_off) {
  58                 tdb->stats.frees++;
  59                 ecode = add_free_record(tdb, old_off,
  60                                         sizeof(struct tdb_used_record)
  61                                         + key.dsize + old_room,
  62                                         TDB_LOCK_WAIT, true);
  63                 if (ecode == TDB_SUCCESS)
  64                         ecode = replace_in_hash(tdb, h, new_off);
  65         } else {
  66                 ecode = add_to_hash(tdb, h, new_off);
  67         }
  68         if (ecode != TDB_SUCCESS) {
  69                 return ecode;
  70         }
  71
  72         new_off += sizeof(struct tdb_used_record);
  73         ecode = tdb->tdb2.io->twrite(tdb, new_off, key.dptr, key.dsize);
  74         if (ecode != TDB_SUCCESS) {
  75                 return ecode;
  76         }
  77
  78         new_off += key.dsize;
  79         ecode = tdb->tdb2.io->twrite(tdb, new_off, dbuf.dptr, dbuf.dsize);
  80         if (ecode != TDB_SUCCESS) {
  81                 return ecode;
  82         }
  83
  84         if (tdb->flags & TDB_SEQNUM)
  85                 tdb_inc_seqnum(tdb);
  86
  87         return TDB_SUCCESS;
  88 }
  89
  90 static enum TDB_ERROR update_data(struct tdb_context *tdb,
  91                                   tdb_off_t off,
  92                                   struct tdb_data dbuf,
  93                                   tdb_len_t extra)
  94 {
  95         enum TDB_ERROR ecode;
  96
  97         ecode = tdb->tdb2.io->twrite(tdb, off, dbuf.dptr, dbuf.dsize);
  98         if (ecode == TDB_SUCCESS && extra) {
  99                 /* Put a zero in; future versions may append other data. */
 100                 ecode = tdb->tdb2.io->twrite(tdb, off + dbuf.dsize, "", 1);
 101         }
 102         if (tdb->flags & TDB_SEQNUM)
 103                 tdb_inc_seqnum(tdb);
 104
 105         return ecode;
 106 }
 107
 108 enum TDB_ERROR tdb_store(struct tdb_context *tdb,
 109                          struct tdb_data key, struct tdb_data dbuf, int flag)
 110 {
 111         struct hash_info h;
 112         tdb_off_t off;
 113         tdb_len_t old_room = 0;
 114         struct tdb_used_record rec;
 115         enum TDB_ERROR ecode;
 116
 117         if (tdb->flags & TDB_VERSION1) {
 118                 if (tdb1_store(tdb, key, dbuf, flag) == -1)
 119                         return tdb->last_error;
 120                 return TDB_SUCCESS;
 121         }
 122
 123         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 124         if (TDB_OFF_IS_ERR(off)) {
 125                 return tdb->last_error = off;
 126         }
 127
 128         /* Now we have lock on this hash bucket. */
 129         if (flag == TDB_INSERT) {
 130                 if (off) {
 131                         ecode = TDB_ERR_EXISTS;
 132                         goto out;
 133                 }
 134         } else {
 135                 if (off) {
 136                         old_room = rec_data_length(&rec)
 137                                 + rec_extra_padding(&rec);
 138                         if (old_room >= dbuf.dsize) {
 139                                 /* Can modify in-place.  Easy! */
 140                                 ecode = update_rec_hdr(tdb, off,
 141                                                        key.dsize, dbuf.dsize,
 142                                                        &rec, h.h);
 143                                 if (ecode != TDB_SUCCESS) {
 144                                         goto out;
 145                                 }
 146                                 ecode = update_data(tdb,
 147                                                     off + sizeof(rec)
 148                                                     + key.dsize, dbuf,
 149                                                     old_room - dbuf.dsize);
 150                                 if (ecode != TDB_SUCCESS) {
 151                                         goto out;
 152                                 }
 153                                 tdb_unlock_hashes(tdb, h.hlock_start,
 154                                                   h.hlock_range, F_WRLCK);
 155                                 return tdb->last_error = TDB_SUCCESS;
 156                         }
 157                 } else {
 158                         if (flag == TDB_MODIFY) {
 159                                 /* if the record doesn't exist and we
 160                                    are in TDB_MODIFY mode then we should fail
 161                                    the store */
 162                                 ecode = TDB_ERR_NOEXIST;
 163                                 goto out;
 164                         }
 165                 }
 166         }
 167
 168         /* If we didn't use the old record, this implies we're growing. */
 169         ecode = replace_data(tdb, &h, key, dbuf, off, old_room, off);
 170 out:
 171         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 172         return tdb->last_error = ecode;
 173 }
 174
 175 enum TDB_ERROR tdb_append(struct tdb_context *tdb,
 176                           struct tdb_data key, struct tdb_data dbuf)
 177 {
 178         struct hash_info h;
 179         tdb_off_t off;
 180         struct tdb_used_record rec;
 181         tdb_len_t old_room = 0, old_dlen;
 182         unsigned char *newdata;
 183         struct tdb_data new_dbuf;
 184         enum TDB_ERROR ecode;
 185
 186         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 187         if (TDB_OFF_IS_ERR(off)) {
 188                 return tdb->last_error = off;
 189         }
 190
 191         if (off) {
 192                 old_dlen = rec_data_length(&rec);
 193                 old_room = old_dlen + rec_extra_padding(&rec);
 194
 195                 /* Fast path: can append in place. */
 196                 if (rec_extra_padding(&rec) >= dbuf.dsize) {
 197                         ecode = update_rec_hdr(tdb, off, key.dsize,
 198                                                old_dlen + dbuf.dsize, &rec,
 199                                                h.h);
 200                         if (ecode != TDB_SUCCESS) {
 201                                 goto out;
 202                         }
 203
 204                         off += sizeof(rec) + key.dsize + old_dlen;
 205                         ecode = update_data(tdb, off, dbuf,
 206                                             rec_extra_padding(&rec));
 207                         goto out;
 208                 }
 209
 210                 /* Slow path. */
 211                 newdata = malloc(key.dsize + old_dlen + dbuf.dsize);
 212                 if (!newdata) {
 213                         ecode = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
 214                                            "tdb_append:"
 215                                            " failed to allocate %zu bytes",
 216                                            (size_t)(key.dsize + old_dlen
 217                                                     + dbuf.dsize));
 218                         goto out;
 219                 }
 220                 ecode = tdb->tdb2.io->tread(tdb, off + sizeof(rec) + key.dsize,
 221                                             newdata, old_dlen);
 222                 if (ecode != TDB_SUCCESS) {
 223                         goto out_free_newdata;
 224                 }
 225                 memcpy(newdata + old_dlen, dbuf.dptr, dbuf.dsize);
 226                 new_dbuf.dptr = newdata;
 227                 new_dbuf.dsize = old_dlen + dbuf.dsize;
 228         } else {
 229                 newdata = NULL;
 230                 new_dbuf = dbuf;
 231         }
 232
 233         /* If they're using tdb_append(), it implies they're growing record. */
 234         ecode = replace_data(tdb, &h, key, new_dbuf, off, old_room, true);
 235
 236 out_free_newdata:
 237         free(newdata);
 238 out:
 239         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 240         return tdb->last_error = ecode;
 241 }
 242
 243 enum TDB_ERROR tdb_fetch(struct tdb_context *tdb, struct tdb_data key,
 244                          struct tdb_data *data)
 245 {
 246         tdb_off_t off;
 247         struct tdb_used_record rec;
 248         struct hash_info h;
 249         enum TDB_ERROR ecode;
 250
 251         if (tdb->flags & TDB_VERSION1)
 252                 return tdb1_fetch(tdb, key, data);
 253
 254         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 255         if (TDB_OFF_IS_ERR(off)) {
 256                 return tdb->last_error = off;
 257         }
 258
 259         if (!off) {
 260                 ecode = TDB_ERR_NOEXIST;
 261         } else {
 262                 data->dsize = rec_data_length(&rec);
 263                 data->dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
 264                                             data->dsize);
 265                 if (TDB_PTR_IS_ERR(data->dptr)) {
 266                         ecode = TDB_PTR_ERR(data->dptr);
 267                 } else
 268                         ecode = TDB_SUCCESS;
 269         }
 270
 271         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 272         return tdb->last_error = ecode;
 273 }
 274
 275 bool tdb_exists(struct tdb_context *tdb, TDB_DATA key)
 276 {
 277         tdb_off_t off;
 278         struct tdb_used_record rec;
 279         struct hash_info h;
 280
 281         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 282         if (TDB_OFF_IS_ERR(off)) {
 283                 tdb->last_error = off;
 284                 return false;
 285         }
 286         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 287
 288         tdb->last_error = TDB_SUCCESS;
 289         return off ? true : false;
 290 }
 291
 292 enum TDB_ERROR tdb_delete(struct tdb_context *tdb, struct tdb_data key)
 293 {
 294         tdb_off_t off;
 295         struct tdb_used_record rec;
 296         struct hash_info h;
 297         enum TDB_ERROR ecode;
 298
 299         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 300         if (TDB_OFF_IS_ERR(off)) {
 301                 return tdb->last_error = off;
 302         }
 303
 304         if (!off) {
 305                 ecode = TDB_ERR_NOEXIST;
 306                 goto unlock;
 307         }
 308
 309         ecode = delete_from_hash(tdb, &h);
 310         if (ecode != TDB_SUCCESS) {
 311                 goto unlock;
 312         }
 313
 314         /* Free the deleted entry. */
 315         tdb->stats.frees++;
 316         ecode = add_free_record(tdb, off,
 317                                 sizeof(struct tdb_used_record)
 318                                 + rec_key_length(&rec)
 319                                 + rec_data_length(&rec)
 320                                 + rec_extra_padding(&rec),
 321                                 TDB_LOCK_WAIT, true);
 322
 323         if (tdb->flags & TDB_SEQNUM)
 324                 tdb_inc_seqnum(tdb);
 325
 326 unlock:
 327         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 328         return tdb->last_error = ecode;
 329 }
 330
 331 unsigned int tdb_get_flags(struct tdb_context *tdb)
 332 {
 333         return tdb->flags;
 334 }
 335
 336 static bool inside_transaction(const struct tdb_context *tdb)
 337 {
 338         if (tdb->flags & TDB_VERSION1)
 339                 return tdb->tdb1.transaction != NULL;
 340         else
 341                 return tdb->tdb2.transaction != NULL;
 342 }
 343
 344 static bool readonly_changable(struct tdb_context *tdb, const char *caller)
 345 {
 346         if (inside_transaction(tdb)) {
 347                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 348                                              TDB_LOG_USE_ERROR,
 349                                              "%s: can't change"
 350                                              " TDB_RDONLY inside transaction",
 351                                              caller);
 352                 return false;
 353         }
 354
 355         if (tdb->file->allrecord_lock.count != 0
 356             || tdb->file->num_lockrecs != 0) {
 357                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 358                                              TDB_LOG_USE_ERROR,
 359                                              "%s: can't change"
 360                                              " TDB_RDONLY holding locks",
 361                                              caller);
 362                 return false;
 363         }
 364         return true;
 365 }
 366
 367 void tdb_add_flag(struct tdb_context *tdb, unsigned flag)
 368 {
 369         if (tdb->flags & TDB_INTERNAL) {
 370                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 371                                              TDB_LOG_USE_ERROR,
 372                                              "tdb_add_flag: internal db");
 373                 return;
 374         }
 375         switch (flag) {
 376         case TDB_NOLOCK:
 377                 tdb->flags |= TDB_NOLOCK;
 378                 break;
 379         case TDB_NOMMAP:
 380                 tdb->flags |= TDB_NOMMAP;
 381                 tdb_munmap(tdb->file);
 382                 break;
 383         case TDB_NOSYNC:
 384                 tdb->flags |= TDB_NOSYNC;
 385                 break;
 386         case TDB_SEQNUM:
 387                 tdb->flags |= TDB_SEQNUM;
 388                 break;
 389         case TDB_ALLOW_NESTING:
 390                 tdb->flags |= TDB_ALLOW_NESTING;
 391                 break;
 392         case TDB_RDONLY:
 393                 if (readonly_changable(tdb, "tdb_add_flag"))
 394                         tdb->flags |= TDB_RDONLY;
 395                 break;
 396         default:
 397                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 398                                              TDB_LOG_USE_ERROR,
 399                                              "tdb_add_flag: Unknown flag %u",
 400                                              flag);
 401         }
 402 }
 403
 404 void tdb_remove_flag(struct tdb_context *tdb, unsigned flag)
 405 {
 406         if (tdb->flags & TDB_INTERNAL) {
 407                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 408                                              TDB_LOG_USE_ERROR,
 409                                              "tdb_remove_flag: internal db");
 410                 return;
 411         }
 412         switch (flag) {
 413         case TDB_NOLOCK:
 414                 tdb->flags &= ~TDB_NOLOCK;
 415                 break;
 416         case TDB_NOMMAP:
 417                 tdb->flags &= ~TDB_NOMMAP;
 418                 tdb_mmap(tdb);
 419                 break;
 420         case TDB_NOSYNC:
 421                 tdb->flags &= ~TDB_NOSYNC;
 422                 break;
 423         case TDB_SEQNUM:
 424                 tdb->flags &= ~TDB_SEQNUM;
 425                 break;
 426         case TDB_ALLOW_NESTING:
 427                 tdb->flags &= ~TDB_ALLOW_NESTING;
 428                 break;
 429         case TDB_RDONLY:
 430                 if ((tdb->open_flags & O_ACCMODE) == O_RDONLY) {
 431                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 432                                                      TDB_LOG_USE_ERROR,
 433                                                      "tdb_remove_flag: can't"
 434                                                      " remove TDB_RDONLY on tdb"
 435                                                      " opened with O_RDONLY");
 436                         break;
 437                 }
 438                 if (readonly_changable(tdb, "tdb_remove_flag"))
 439                         tdb->flags &= ~TDB_RDONLY;
 440                 break;
 441         default:
 442                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 443                                              TDB_LOG_USE_ERROR,
 444                                              "tdb_remove_flag: Unknown flag %u",
 445                                              flag);
 446         }
 447 }
 448
 449 const char *tdb_errorstr(enum TDB_ERROR ecode)
 450 {
 451         /* Gcc warns if you miss a case in the switch, so use that. */
 452         switch (ecode) {
 453         case TDB_SUCCESS: return "Success";
 454         case TDB_ERR_CORRUPT: return "Corrupt database";
 455         case TDB_ERR_IO: return "IO Error";
 456         case TDB_ERR_LOCK: return "Locking error";
 457         case TDB_ERR_OOM: return "Out of memory";
 458         case TDB_ERR_EXISTS: return "Record exists";
 459         case TDB_ERR_EINVAL: return "Invalid parameter";
 460         case TDB_ERR_NOEXIST: return "Record does not exist";
 461         case TDB_ERR_RDONLY: return "write not permitted";
 462         }
 463         return "Invalid error code";
 464 }
 465
 466 enum TDB_ERROR tdb_error(struct tdb_context *tdb)
 467 {
 468         return tdb->last_error;
 469 }
 470
 471 enum TDB_ERROR COLD tdb_logerr(struct tdb_context *tdb,
 472                                enum TDB_ERROR ecode,
 473                                enum tdb_log_level level,
 474                                const char *fmt, ...)
 475 {
 476         char *message;
 477         va_list ap;
 478         size_t len;
 479         /* tdb_open paths care about errno, so save it. */
 480         int saved_errno = errno;
 481
 482         if (!tdb->log_fn)
 483                 return ecode;
 484
 485         va_start(ap, fmt);
 486         len = vasprintf(&message, fmt, ap);
 487         va_end(ap);
 488
 489         if (len < 0) {
 490                 tdb->log_fn(tdb, TDB_LOG_ERROR, TDB_ERR_OOM,
 491                             "out of memory formatting message:", tdb->log_data);
 492                 tdb->log_fn(tdb, level, ecode, fmt, tdb->log_data);
 493         } else {
 494                 tdb->log_fn(tdb, level, ecode, message, tdb->log_data);
 495                 free(message);
 496         }
 497         errno = saved_errno;
 498         return ecode;
 499 }
 500
 501 enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb,
 502                                  TDB_DATA key,
 503                                  enum TDB_ERROR (*parse)(TDB_DATA k,
 504                                                          TDB_DATA d,
 505                                                          void *data),
 506                                  void *data)
 507 {
 508         tdb_off_t off;
 509         struct tdb_used_record rec;
 510         struct hash_info h;
 511         enum TDB_ERROR ecode;
 512
 513         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 514         if (TDB_OFF_IS_ERR(off)) {
 515                 return tdb->last_error = off;
 516         }
 517
 518         if (!off) {
 519                 ecode = TDB_ERR_NOEXIST;
 520         } else {
 521                 const void *dptr;
 522                 dptr = tdb_access_read(tdb, off + sizeof(rec) + key.dsize,
 523                                        rec_data_length(&rec), false);
 524                 if (TDB_PTR_IS_ERR(dptr)) {
 525                         ecode = TDB_PTR_ERR(dptr);
 526                 } else {
 527                         TDB_DATA d = tdb_mkdata(dptr, rec_data_length(&rec));
 528
 529                         ecode = parse(key, d, data);
 530                         tdb_access_release(tdb, dptr);
 531                 }
 532         }
 533
 534         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 535         return tdb->last_error = ecode;
 536 }
 537
 538 const char *tdb_name(const struct tdb_context *tdb)
 539 {
 540         return tdb->name;
 541 }
 542
 543 int64_t tdb_get_seqnum(struct tdb_context *tdb)
 544 {
 545         tdb_off_t off = tdb_read_off(tdb, offsetof(struct tdb_header, seqnum));
 546         if (TDB_OFF_IS_ERR(off))
 547                 tdb->last_error = off;
 548         else
 549                 tdb->last_error = TDB_SUCCESS;
 550         return off;
 551 }
 552
 553
 554 int tdb_fd(const struct tdb_context *tdb)
 555 {
 556         return tdb->file->fd;
 557 }