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         if (tdb->flags & TDB_VERSION1) {
 187                 if (tdb1_append(tdb, key, dbuf) == -1)
 188                         return tdb->last_error;
 189                 return TDB_SUCCESS;
 190         }
 191
 192         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 193         if (TDB_OFF_IS_ERR(off)) {
 194                 return tdb->last_error = off;
 195         }
 196
 197         if (off) {
 198                 old_dlen = rec_data_length(&rec);
 199                 old_room = old_dlen + rec_extra_padding(&rec);
 200
 201                 /* Fast path: can append in place. */
 202                 if (rec_extra_padding(&rec) >= dbuf.dsize) {
 203                         ecode = update_rec_hdr(tdb, off, key.dsize,
 204                                                old_dlen + dbuf.dsize, &rec,
 205                                                h.h);
 206                         if (ecode != TDB_SUCCESS) {
 207                                 goto out;
 208                         }
 209
 210                         off += sizeof(rec) + key.dsize + old_dlen;
 211                         ecode = update_data(tdb, off, dbuf,
 212                                             rec_extra_padding(&rec));
 213                         goto out;
 214                 }
 215
 216                 /* Slow path. */
 217                 newdata = malloc(key.dsize + old_dlen + dbuf.dsize);
 218                 if (!newdata) {
 219                         ecode = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
 220                                            "tdb_append:"
 221                                            " failed to allocate %zu bytes",
 222                                            (size_t)(key.dsize + old_dlen
 223                                                     + dbuf.dsize));
 224                         goto out;
 225                 }
 226                 ecode = tdb->tdb2.io->tread(tdb, off + sizeof(rec) + key.dsize,
 227                                             newdata, old_dlen);
 228                 if (ecode != TDB_SUCCESS) {
 229                         goto out_free_newdata;
 230                 }
 231                 memcpy(newdata + old_dlen, dbuf.dptr, dbuf.dsize);
 232                 new_dbuf.dptr = newdata;
 233                 new_dbuf.dsize = old_dlen + dbuf.dsize;
 234         } else {
 235                 newdata = NULL;
 236                 new_dbuf = dbuf;
 237         }
 238
 239         /* If they're using tdb_append(), it implies they're growing record. */
 240         ecode = replace_data(tdb, &h, key, new_dbuf, off, old_room, true);
 241
 242 out_free_newdata:
 243         free(newdata);
 244 out:
 245         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 246         return tdb->last_error = ecode;
 247 }
 248
 249 enum TDB_ERROR tdb_fetch(struct tdb_context *tdb, struct tdb_data key,
 250                          struct tdb_data *data)
 251 {
 252         tdb_off_t off;
 253         struct tdb_used_record rec;
 254         struct hash_info h;
 255         enum TDB_ERROR ecode;
 256
 257         if (tdb->flags & TDB_VERSION1)
 258                 return tdb1_fetch(tdb, key, data);
 259
 260         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 261         if (TDB_OFF_IS_ERR(off)) {
 262                 return tdb->last_error = off;
 263         }
 264
 265         if (!off) {
 266                 ecode = TDB_ERR_NOEXIST;
 267         } else {
 268                 data->dsize = rec_data_length(&rec);
 269                 data->dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
 270                                             data->dsize);
 271                 if (TDB_PTR_IS_ERR(data->dptr)) {
 272                         ecode = TDB_PTR_ERR(data->dptr);
 273                 } else
 274                         ecode = TDB_SUCCESS;
 275         }
 276
 277         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 278         return tdb->last_error = ecode;
 279 }
 280
 281 bool tdb_exists(struct tdb_context *tdb, TDB_DATA key)
 282 {
 283         tdb_off_t off;
 284         struct tdb_used_record rec;
 285         struct hash_info h;
 286
 287         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 288         if (TDB_OFF_IS_ERR(off)) {
 289                 tdb->last_error = off;
 290                 return false;
 291         }
 292         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 293
 294         tdb->last_error = TDB_SUCCESS;
 295         return off ? true : false;
 296 }
 297
 298 enum TDB_ERROR tdb_delete(struct tdb_context *tdb, struct tdb_data key)
 299 {
 300         tdb_off_t off;
 301         struct tdb_used_record rec;
 302         struct hash_info h;
 303         enum TDB_ERROR ecode;
 304
 305         if (tdb->flags & TDB_VERSION1) {
 306                 if (tdb1_delete(tdb, key) == -1)
 307                         return tdb->last_error;
 308                 return TDB_SUCCESS;
 309         }
 310
 311         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 312         if (TDB_OFF_IS_ERR(off)) {
 313                 return tdb->last_error = off;
 314         }
 315
 316         if (!off) {
 317                 ecode = TDB_ERR_NOEXIST;
 318                 goto unlock;
 319         }
 320
 321         ecode = delete_from_hash(tdb, &h);
 322         if (ecode != TDB_SUCCESS) {
 323                 goto unlock;
 324         }
 325
 326         /* Free the deleted entry. */
 327         tdb->stats.frees++;
 328         ecode = add_free_record(tdb, off,
 329                                 sizeof(struct tdb_used_record)
 330                                 + rec_key_length(&rec)
 331                                 + rec_data_length(&rec)
 332                                 + rec_extra_padding(&rec),
 333                                 TDB_LOCK_WAIT, true);
 334
 335         if (tdb->flags & TDB_SEQNUM)
 336                 tdb_inc_seqnum(tdb);
 337
 338 unlock:
 339         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 340         return tdb->last_error = ecode;
 341 }
 342
 343 unsigned int tdb_get_flags(struct tdb_context *tdb)
 344 {
 345         return tdb->flags;
 346 }
 347
 348 static bool inside_transaction(const struct tdb_context *tdb)
 349 {
 350         if (tdb->flags & TDB_VERSION1)
 351                 return tdb->tdb1.transaction != NULL;
 352         else
 353                 return tdb->tdb2.transaction != NULL;
 354 }
 355
 356 static bool readonly_changable(struct tdb_context *tdb, const char *caller)
 357 {
 358         if (inside_transaction(tdb)) {
 359                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 360                                              TDB_LOG_USE_ERROR,
 361                                              "%s: can't change"
 362                                              " TDB_RDONLY inside transaction",
 363                                              caller);
 364                 return false;
 365         }
 366
 367         if (tdb->file->allrecord_lock.count != 0
 368             || tdb->file->num_lockrecs != 0) {
 369                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 370                                              TDB_LOG_USE_ERROR,
 371                                              "%s: can't change"
 372                                              " TDB_RDONLY holding locks",
 373                                              caller);
 374                 return false;
 375         }
 376         return true;
 377 }
 378
 379 void tdb_add_flag(struct tdb_context *tdb, unsigned flag)
 380 {
 381         if (tdb->flags & TDB_INTERNAL) {
 382                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 383                                              TDB_LOG_USE_ERROR,
 384                                              "tdb_add_flag: internal db");
 385                 return;
 386         }
 387         switch (flag) {
 388         case TDB_NOLOCK:
 389                 tdb->flags |= TDB_NOLOCK;
 390                 break;
 391         case TDB_NOMMAP:
 392                 tdb->flags |= TDB_NOMMAP;
 393                 tdb_munmap(tdb->file);
 394                 break;
 395         case TDB_NOSYNC:
 396                 tdb->flags |= TDB_NOSYNC;
 397                 break;
 398         case TDB_SEQNUM:
 399                 tdb->flags |= TDB_SEQNUM;
 400                 break;
 401         case TDB_ALLOW_NESTING:
 402                 tdb->flags |= TDB_ALLOW_NESTING;
 403                 break;
 404         case TDB_RDONLY:
 405                 if (readonly_changable(tdb, "tdb_add_flag"))
 406                         tdb->flags |= TDB_RDONLY;
 407                 break;
 408         default:
 409                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 410                                              TDB_LOG_USE_ERROR,
 411                                              "tdb_add_flag: Unknown flag %u",
 412                                              flag);
 413         }
 414 }
 415
 416 void tdb_remove_flag(struct tdb_context *tdb, unsigned flag)
 417 {
 418         if (tdb->flags & TDB_INTERNAL) {
 419                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 420                                              TDB_LOG_USE_ERROR,
 421                                              "tdb_remove_flag: internal db");
 422                 return;
 423         }
 424         switch (flag) {
 425         case TDB_NOLOCK:
 426                 tdb->flags &= ~TDB_NOLOCK;
 427                 break;
 428         case TDB_NOMMAP:
 429                 tdb->flags &= ~TDB_NOMMAP;
 430                 tdb_mmap(tdb);
 431                 break;
 432         case TDB_NOSYNC:
 433                 tdb->flags &= ~TDB_NOSYNC;
 434                 break;
 435         case TDB_SEQNUM:
 436                 tdb->flags &= ~TDB_SEQNUM;
 437                 break;
 438         case TDB_ALLOW_NESTING:
 439                 tdb->flags &= ~TDB_ALLOW_NESTING;
 440                 break;
 441         case TDB_RDONLY:
 442                 if ((tdb->open_flags & O_ACCMODE) == O_RDONLY) {
 443                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 444                                                      TDB_LOG_USE_ERROR,
 445                                                      "tdb_remove_flag: can't"
 446                                                      " remove TDB_RDONLY on tdb"
 447                                                      " opened with O_RDONLY");
 448                         break;
 449                 }
 450                 if (readonly_changable(tdb, "tdb_remove_flag"))
 451                         tdb->flags &= ~TDB_RDONLY;
 452                 break;
 453         default:
 454                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 455                                              TDB_LOG_USE_ERROR,
 456                                              "tdb_remove_flag: Unknown flag %u",
 457                                              flag);
 458         }
 459 }
 460
 461 const char *tdb_errorstr(enum TDB_ERROR ecode)
 462 {
 463         /* Gcc warns if you miss a case in the switch, so use that. */
 464         switch (ecode) {
 465         case TDB_SUCCESS: return "Success";
 466         case TDB_ERR_CORRUPT: return "Corrupt database";
 467         case TDB_ERR_IO: return "IO Error";
 468         case TDB_ERR_LOCK: return "Locking error";
 469         case TDB_ERR_OOM: return "Out of memory";
 470         case TDB_ERR_EXISTS: return "Record exists";
 471         case TDB_ERR_EINVAL: return "Invalid parameter";
 472         case TDB_ERR_NOEXIST: return "Record does not exist";
 473         case TDB_ERR_RDONLY: return "write not permitted";
 474         }
 475         return "Invalid error code";
 476 }
 477
 478 enum TDB_ERROR tdb_error(struct tdb_context *tdb)
 479 {
 480         return tdb->last_error;
 481 }
 482
 483 enum TDB_ERROR COLD tdb_logerr(struct tdb_context *tdb,
 484                                enum TDB_ERROR ecode,
 485                                enum tdb_log_level level,
 486                                const char *fmt, ...)
 487 {
 488         char *message;
 489         va_list ap;
 490         size_t len;
 491         /* tdb_open paths care about errno, so save it. */
 492         int saved_errno = errno;
 493
 494         if (!tdb->log_fn)
 495                 return ecode;
 496
 497         va_start(ap, fmt);
 498         len = vasprintf(&message, fmt, ap);
 499         va_end(ap);
 500
 501         if (len < 0) {
 502                 tdb->log_fn(tdb, TDB_LOG_ERROR, TDB_ERR_OOM,
 503                             "out of memory formatting message:", tdb->log_data);
 504                 tdb->log_fn(tdb, level, ecode, fmt, tdb->log_data);
 505         } else {
 506                 tdb->log_fn(tdb, level, ecode, message, tdb->log_data);
 507                 free(message);
 508         }
 509         errno = saved_errno;
 510         return ecode;
 511 }
 512
 513 enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb,
 514                                  TDB_DATA key,
 515                                  enum TDB_ERROR (*parse)(TDB_DATA k,
 516                                                          TDB_DATA d,
 517                                                          void *data),
 518                                  void *data)
 519 {
 520         tdb_off_t off;
 521         struct tdb_used_record rec;
 522         struct hash_info h;
 523         enum TDB_ERROR ecode;
 524
 525         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 526         if (TDB_OFF_IS_ERR(off)) {
 527                 return tdb->last_error = off;
 528         }
 529
 530         if (!off) {
 531                 ecode = TDB_ERR_NOEXIST;
 532         } else {
 533                 const void *dptr;
 534                 dptr = tdb_access_read(tdb, off + sizeof(rec) + key.dsize,
 535                                        rec_data_length(&rec), false);
 536                 if (TDB_PTR_IS_ERR(dptr)) {
 537                         ecode = TDB_PTR_ERR(dptr);
 538                 } else {
 539                         TDB_DATA d = tdb_mkdata(dptr, rec_data_length(&rec));
 540
 541                         ecode = parse(key, d, data);
 542                         tdb_access_release(tdb, dptr);
 543                 }
 544         }
 545
 546         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 547         return tdb->last_error = ecode;
 548 }
 549
 550 const char *tdb_name(const struct tdb_context *tdb)
 551 {
 552         return tdb->name;
 553 }
 554
 555 int64_t tdb_get_seqnum(struct tdb_context *tdb)
 556 {
 557         tdb_off_t off = tdb_read_off(tdb, offsetof(struct tdb_header, seqnum));
 558         if (TDB_OFF_IS_ERR(off))
 559                 tdb->last_error = off;
 560         else
 561                 tdb->last_error = TDB_SUCCESS;
 562         return off;
 563 }
 564
 565
 566 int tdb_fd(const struct tdb_context *tdb)
 567 {
 568         return tdb->file->fd;
 569 }