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         if (tdb->flags & TDB_VERSION1) {
 288                 return tdb1_exists(tdb, key);
 289         }
 290
 291         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 292         if (TDB_OFF_IS_ERR(off)) {
 293                 tdb->last_error = off;
 294                 return false;
 295         }
 296         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 297
 298         tdb->last_error = TDB_SUCCESS;
 299         return off ? true : false;
 300 }
 301
 302 enum TDB_ERROR tdb_delete(struct tdb_context *tdb, struct tdb_data key)
 303 {
 304         tdb_off_t off;
 305         struct tdb_used_record rec;
 306         struct hash_info h;
 307         enum TDB_ERROR ecode;
 308
 309         if (tdb->flags & TDB_VERSION1) {
 310                 if (tdb1_delete(tdb, key) == -1)
 311                         return tdb->last_error;
 312                 return TDB_SUCCESS;
 313         }
 314
 315         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 316         if (TDB_OFF_IS_ERR(off)) {
 317                 return tdb->last_error = off;
 318         }
 319
 320         if (!off) {
 321                 ecode = TDB_ERR_NOEXIST;
 322                 goto unlock;
 323         }
 324
 325         ecode = delete_from_hash(tdb, &h);
 326         if (ecode != TDB_SUCCESS) {
 327                 goto unlock;
 328         }
 329
 330         /* Free the deleted entry. */
 331         tdb->stats.frees++;
 332         ecode = add_free_record(tdb, off,
 333                                 sizeof(struct tdb_used_record)
 334                                 + rec_key_length(&rec)
 335                                 + rec_data_length(&rec)
 336                                 + rec_extra_padding(&rec),
 337                                 TDB_LOCK_WAIT, true);
 338
 339         if (tdb->flags & TDB_SEQNUM)
 340                 tdb_inc_seqnum(tdb);
 341
 342 unlock:
 343         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 344         return tdb->last_error = ecode;
 345 }
 346
 347 unsigned int tdb_get_flags(struct tdb_context *tdb)
 348 {
 349         return tdb->flags;
 350 }
 351
 352 static bool inside_transaction(const struct tdb_context *tdb)
 353 {
 354         if (tdb->flags & TDB_VERSION1)
 355                 return tdb->tdb1.transaction != NULL;
 356         else
 357                 return tdb->tdb2.transaction != NULL;
 358 }
 359
 360 static bool readonly_changable(struct tdb_context *tdb, const char *caller)
 361 {
 362         if (inside_transaction(tdb)) {
 363                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 364                                              TDB_LOG_USE_ERROR,
 365                                              "%s: can't change"
 366                                              " TDB_RDONLY inside transaction",
 367                                              caller);
 368                 return false;
 369         }
 370
 371         if (tdb->file->allrecord_lock.count != 0
 372             || tdb->file->num_lockrecs != 0) {
 373                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 374                                              TDB_LOG_USE_ERROR,
 375                                              "%s: can't change"
 376                                              " TDB_RDONLY holding locks",
 377                                              caller);
 378                 return false;
 379         }
 380         return true;
 381 }
 382
 383 void tdb_add_flag(struct tdb_context *tdb, unsigned flag)
 384 {
 385         if (tdb->flags & TDB_INTERNAL) {
 386                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 387                                              TDB_LOG_USE_ERROR,
 388                                              "tdb_add_flag: internal db");
 389                 return;
 390         }
 391         switch (flag) {
 392         case TDB_NOLOCK:
 393                 tdb->flags |= TDB_NOLOCK;
 394                 break;
 395         case TDB_NOMMAP:
 396                 tdb->flags |= TDB_NOMMAP;
 397                 tdb_munmap(tdb->file);
 398                 break;
 399         case TDB_NOSYNC:
 400                 tdb->flags |= TDB_NOSYNC;
 401                 break;
 402         case TDB_SEQNUM:
 403                 tdb->flags |= TDB_SEQNUM;
 404                 break;
 405         case TDB_ALLOW_NESTING:
 406                 tdb->flags |= TDB_ALLOW_NESTING;
 407                 break;
 408         case TDB_RDONLY:
 409                 if (readonly_changable(tdb, "tdb_add_flag"))
 410                         tdb->flags |= TDB_RDONLY;
 411                 break;
 412         default:
 413                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 414                                              TDB_LOG_USE_ERROR,
 415                                              "tdb_add_flag: Unknown flag %u",
 416                                              flag);
 417         }
 418 }
 419
 420 void tdb_remove_flag(struct tdb_context *tdb, unsigned flag)
 421 {
 422         if (tdb->flags & TDB_INTERNAL) {
 423                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 424                                              TDB_LOG_USE_ERROR,
 425                                              "tdb_remove_flag: internal db");
 426                 return;
 427         }
 428         switch (flag) {
 429         case TDB_NOLOCK:
 430                 tdb->flags &= ~TDB_NOLOCK;
 431                 break;
 432         case TDB_NOMMAP:
 433                 tdb->flags &= ~TDB_NOMMAP;
 434                 tdb_mmap(tdb);
 435                 break;
 436         case TDB_NOSYNC:
 437                 tdb->flags &= ~TDB_NOSYNC;
 438                 break;
 439         case TDB_SEQNUM:
 440                 tdb->flags &= ~TDB_SEQNUM;
 441                 break;
 442         case TDB_ALLOW_NESTING:
 443                 tdb->flags &= ~TDB_ALLOW_NESTING;
 444                 break;
 445         case TDB_RDONLY:
 446                 if ((tdb->open_flags & O_ACCMODE) == O_RDONLY) {
 447                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 448                                                      TDB_LOG_USE_ERROR,
 449                                                      "tdb_remove_flag: can't"
 450                                                      " remove TDB_RDONLY on tdb"
 451                                                      " opened with O_RDONLY");
 452                         break;
 453                 }
 454                 if (readonly_changable(tdb, "tdb_remove_flag"))
 455                         tdb->flags &= ~TDB_RDONLY;
 456                 break;
 457         default:
 458                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 459                                              TDB_LOG_USE_ERROR,
 460                                              "tdb_remove_flag: Unknown flag %u",
 461                                              flag);
 462         }
 463 }
 464
 465 const char *tdb_errorstr(enum TDB_ERROR ecode)
 466 {
 467         /* Gcc warns if you miss a case in the switch, so use that. */
 468         switch (ecode) {
 469         case TDB_SUCCESS: return "Success";
 470         case TDB_ERR_CORRUPT: return "Corrupt database";
 471         case TDB_ERR_IO: return "IO Error";
 472         case TDB_ERR_LOCK: return "Locking error";
 473         case TDB_ERR_OOM: return "Out of memory";
 474         case TDB_ERR_EXISTS: return "Record exists";
 475         case TDB_ERR_EINVAL: return "Invalid parameter";
 476         case TDB_ERR_NOEXIST: return "Record does not exist";
 477         case TDB_ERR_RDONLY: return "write not permitted";
 478         }
 479         return "Invalid error code";
 480 }
 481
 482 enum TDB_ERROR tdb_error(struct tdb_context *tdb)
 483 {
 484         return tdb->last_error;
 485 }
 486
 487 enum TDB_ERROR COLD tdb_logerr(struct tdb_context *tdb,
 488                                enum TDB_ERROR ecode,
 489                                enum tdb_log_level level,
 490                                const char *fmt, ...)
 491 {
 492         char *message;
 493         va_list ap;
 494         size_t len;
 495         /* tdb_open paths care about errno, so save it. */
 496         int saved_errno = errno;
 497
 498         if (!tdb->log_fn)
 499                 return ecode;
 500
 501         va_start(ap, fmt);
 502         len = vasprintf(&message, fmt, ap);
 503         va_end(ap);
 504
 505         if (len < 0) {
 506                 tdb->log_fn(tdb, TDB_LOG_ERROR, TDB_ERR_OOM,
 507                             "out of memory formatting message:", tdb->log_data);
 508                 tdb->log_fn(tdb, level, ecode, fmt, tdb->log_data);
 509         } else {
 510                 tdb->log_fn(tdb, level, ecode, message, tdb->log_data);
 511                 free(message);
 512         }
 513         errno = saved_errno;
 514         return ecode;
 515 }
 516
 517 enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb,
 518                                  TDB_DATA key,
 519                                  enum TDB_ERROR (*parse)(TDB_DATA k,
 520                                                          TDB_DATA d,
 521                                                          void *data),
 522                                  void *data)
 523 {
 524         tdb_off_t off;
 525         struct tdb_used_record rec;
 526         struct hash_info h;
 527         enum TDB_ERROR ecode;
 528
 529         if (tdb->flags & TDB_VERSION1) {
 530                 return tdb->last_error = tdb1_parse_record(tdb, key, parse,
 531                                                            data);
 532         }
 533
 534         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 535         if (TDB_OFF_IS_ERR(off)) {
 536                 return tdb->last_error = off;
 537         }
 538
 539         if (!off) {
 540                 ecode = TDB_ERR_NOEXIST;
 541         } else {
 542                 const void *dptr;
 543                 dptr = tdb_access_read(tdb, off + sizeof(rec) + key.dsize,
 544                                        rec_data_length(&rec), false);
 545                 if (TDB_PTR_IS_ERR(dptr)) {
 546                         ecode = TDB_PTR_ERR(dptr);
 547                 } else {
 548                         TDB_DATA d = tdb_mkdata(dptr, rec_data_length(&rec));
 549
 550                         ecode = parse(key, d, data);
 551                         tdb_access_release(tdb, dptr);
 552                 }
 553         }
 554
 555         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 556         return tdb->last_error = ecode;
 557 }
 558
 559 const char *tdb_name(const struct tdb_context *tdb)
 560 {
 561         return tdb->name;
 562 }
 563
 564 int64_t tdb_get_seqnum(struct tdb_context *tdb)
 565 {
 566         tdb_off_t off;
 567
 568         if (tdb->flags & TDB_VERSION1) {
 569                 tdb1_off_t val;
 570                 tdb->last_error = TDB_SUCCESS;
 571                 val = tdb1_get_seqnum(tdb);
 572
 573                 if (tdb->last_error != TDB_SUCCESS)
 574                         return tdb->last_error;
 575                 else
 576                         return val;
 577         }
 578
 579         off = tdb_read_off(tdb, offsetof(struct tdb_header, seqnum));
 580         if (TDB_OFF_IS_ERR(off))
 581                 tdb->last_error = off;
 582         else
 583                 tdb->last_error = TDB_SUCCESS;
 584         return off;
 585 }
 586
 587
 588 int tdb_fd(const struct tdb_context *tdb)
 589 {
 590         return tdb->file->fd;
 591 }