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->methods->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->methods->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->methods->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->methods->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         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 118         if (TDB_OFF_IS_ERR(off)) {
 119                 return tdb->last_error = off;
 120         }
 121
 122         /* Now we have lock on this hash bucket. */
 123         if (flag == TDB_INSERT) {
 124                 if (off) {
 125                         ecode = TDB_ERR_EXISTS;
 126                         goto out;
 127                 }
 128         } else {
 129                 if (off) {
 130                         old_room = rec_data_length(&rec)
 131                                 + rec_extra_padding(&rec);
 132                         if (old_room >= dbuf.dsize) {
 133                                 /* Can modify in-place.  Easy! */
 134                                 ecode = update_rec_hdr(tdb, off,
 135                                                        key.dsize, dbuf.dsize,
 136                                                        &rec, h.h);
 137                                 if (ecode != TDB_SUCCESS) {
 138                                         goto out;
 139                                 }
 140                                 ecode = update_data(tdb,
 141                                                     off + sizeof(rec)
 142                                                     + key.dsize, dbuf,
 143                                                     old_room - dbuf.dsize);
 144                                 if (ecode != TDB_SUCCESS) {
 145                                         goto out;
 146                                 }
 147                                 tdb_unlock_hashes(tdb, h.hlock_start,
 148                                                   h.hlock_range, F_WRLCK);
 149                                 return tdb->last_error = TDB_SUCCESS;
 150                         }
 151                 } else {
 152                         if (flag == TDB_MODIFY) {
 153                                 /* if the record doesn't exist and we
 154                                    are in TDB_MODIFY mode then we should fail
 155                                    the store */
 156                                 ecode = TDB_ERR_NOEXIST;
 157                                 goto out;
 158                         }
 159                 }
 160         }
 161
 162         /* If we didn't use the old record, this implies we're growing. */
 163         ecode = replace_data(tdb, &h, key, dbuf, off, old_room, off);
 164 out:
 165         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 166         return tdb->last_error = ecode;
 167 }
 168
 169 enum TDB_ERROR tdb_append(struct tdb_context *tdb,
 170                           struct tdb_data key, struct tdb_data dbuf)
 171 {
 172         struct hash_info h;
 173         tdb_off_t off;
 174         struct tdb_used_record rec;
 175         tdb_len_t old_room = 0, old_dlen;
 176         unsigned char *newdata;
 177         struct tdb_data new_dbuf;
 178         enum TDB_ERROR ecode;
 179
 180         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 181         if (TDB_OFF_IS_ERR(off)) {
 182                 return tdb->last_error = off;
 183         }
 184
 185         if (off) {
 186                 old_dlen = rec_data_length(&rec);
 187                 old_room = old_dlen + rec_extra_padding(&rec);
 188
 189                 /* Fast path: can append in place. */
 190                 if (rec_extra_padding(&rec) >= dbuf.dsize) {
 191                         ecode = update_rec_hdr(tdb, off, key.dsize,
 192                                                old_dlen + dbuf.dsize, &rec,
 193                                                h.h);
 194                         if (ecode != TDB_SUCCESS) {
 195                                 goto out;
 196                         }
 197
 198                         off += sizeof(rec) + key.dsize + old_dlen;
 199                         ecode = update_data(tdb, off, dbuf,
 200                                             rec_extra_padding(&rec));
 201                         goto out;
 202                 }
 203
 204                 /* Slow path. */
 205                 newdata = malloc(key.dsize + old_dlen + dbuf.dsize);
 206                 if (!newdata) {
 207                         ecode = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
 208                                            "tdb_append:"
 209                                            " failed to allocate %zu bytes",
 210                                            (size_t)(key.dsize + old_dlen
 211                                                     + dbuf.dsize));
 212                         goto out;
 213                 }
 214                 ecode = tdb->methods->tread(tdb, off + sizeof(rec) + key.dsize,
 215                                             newdata, old_dlen);
 216                 if (ecode != TDB_SUCCESS) {
 217                         goto out_free_newdata;
 218                 }
 219                 memcpy(newdata + old_dlen, dbuf.dptr, dbuf.dsize);
 220                 new_dbuf.dptr = newdata;
 221                 new_dbuf.dsize = old_dlen + dbuf.dsize;
 222         } else {
 223                 newdata = NULL;
 224                 new_dbuf = dbuf;
 225         }
 226
 227         /* If they're using tdb_append(), it implies they're growing record. */
 228         ecode = replace_data(tdb, &h, key, new_dbuf, off, old_room, true);
 229
 230 out_free_newdata:
 231         free(newdata);
 232 out:
 233         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 234         return tdb->last_error = ecode;
 235 }
 236
 237 enum TDB_ERROR tdb_fetch(struct tdb_context *tdb, struct tdb_data key,
 238                          struct tdb_data *data)
 239 {
 240         tdb_off_t off;
 241         struct tdb_used_record rec;
 242         struct hash_info h;
 243         enum TDB_ERROR ecode;
 244
 245         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 246         if (TDB_OFF_IS_ERR(off)) {
 247                 return tdb->last_error = off;
 248         }
 249
 250         if (!off) {
 251                 ecode = TDB_ERR_NOEXIST;
 252         } else {
 253                 data->dsize = rec_data_length(&rec);
 254                 data->dptr = tdb_alloc_read(tdb, off + sizeof(rec) + key.dsize,
 255                                             data->dsize);
 256                 if (TDB_PTR_IS_ERR(data->dptr)) {
 257                         ecode = TDB_PTR_ERR(data->dptr);
 258                 } else
 259                         ecode = TDB_SUCCESS;
 260         }
 261
 262         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 263         return tdb->last_error = ecode;
 264 }
 265
 266 bool tdb_exists(struct tdb_context *tdb, TDB_DATA key)
 267 {
 268         tdb_off_t off;
 269         struct tdb_used_record rec;
 270         struct hash_info h;
 271
 272         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 273         if (TDB_OFF_IS_ERR(off)) {
 274                 tdb->last_error = off;
 275                 return false;
 276         }
 277         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 278
 279         tdb->last_error = TDB_SUCCESS;
 280         return off ? true : false;
 281 }
 282
 283 enum TDB_ERROR tdb_delete(struct tdb_context *tdb, struct tdb_data key)
 284 {
 285         tdb_off_t off;
 286         struct tdb_used_record rec;
 287         struct hash_info h;
 288         enum TDB_ERROR ecode;
 289
 290         off = find_and_lock(tdb, key, F_WRLCK, &h, &rec, NULL);
 291         if (TDB_OFF_IS_ERR(off)) {
 292                 return tdb->last_error = off;
 293         }
 294
 295         if (!off) {
 296                 ecode = TDB_ERR_NOEXIST;
 297                 goto unlock;
 298         }
 299
 300         ecode = delete_from_hash(tdb, &h);
 301         if (ecode != TDB_SUCCESS) {
 302                 goto unlock;
 303         }
 304
 305         /* Free the deleted entry. */
 306         tdb->stats.frees++;
 307         ecode = add_free_record(tdb, off,
 308                                 sizeof(struct tdb_used_record)
 309                                 + rec_key_length(&rec)
 310                                 + rec_data_length(&rec)
 311                                 + rec_extra_padding(&rec),
 312                                 TDB_LOCK_WAIT, true);
 313
 314         if (tdb->flags & TDB_SEQNUM)
 315                 tdb_inc_seqnum(tdb);
 316
 317 unlock:
 318         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_WRLCK);
 319         return tdb->last_error = ecode;
 320 }
 321
 322 unsigned int tdb_get_flags(struct tdb_context *tdb)
 323 {
 324         return tdb->flags;
 325 }
 326
 327 static bool readonly_changable(struct tdb_context *tdb, const char *caller)
 328 {
 329         if (tdb->transaction) {
 330                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 331                                              TDB_LOG_USE_ERROR,
 332                                              "%s: can't change"
 333                                              " TDB_RDONLY inside transaction",
 334                                              caller);
 335                 return false;
 336         }
 337
 338         if (tdb->file->allrecord_lock.count != 0
 339             || tdb->file->num_lockrecs != 0) {
 340                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 341                                              TDB_LOG_USE_ERROR,
 342                                              "%s: can't change"
 343                                              " TDB_RDONLY holding locks",
 344                                              caller);
 345                 return false;
 346         }
 347         return true;
 348 }
 349
 350 void tdb_add_flag(struct tdb_context *tdb, unsigned flag)
 351 {
 352         if (tdb->flags & TDB_INTERNAL) {
 353                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 354                                              TDB_LOG_USE_ERROR,
 355                                              "tdb_add_flag: internal db");
 356                 return;
 357         }
 358         switch (flag) {
 359         case TDB_NOLOCK:
 360                 tdb->flags |= TDB_NOLOCK;
 361                 break;
 362         case TDB_NOMMAP:
 363                 tdb->flags |= TDB_NOMMAP;
 364                 tdb_munmap(tdb->file);
 365                 break;
 366         case TDB_NOSYNC:
 367                 tdb->flags |= TDB_NOSYNC;
 368                 break;
 369         case TDB_SEQNUM:
 370                 tdb->flags |= TDB_SEQNUM;
 371                 break;
 372         case TDB_ALLOW_NESTING:
 373                 tdb->flags |= TDB_ALLOW_NESTING;
 374                 break;
 375         case TDB_RDONLY:
 376                 if (readonly_changable(tdb, "tdb_add_flag"))
 377                         tdb->flags |= TDB_RDONLY;
 378                 break;
 379         default:
 380                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 381                                              TDB_LOG_USE_ERROR,
 382                                              "tdb_add_flag: Unknown flag %u",
 383                                              flag);
 384         }
 385 }
 386
 387 void tdb_remove_flag(struct tdb_context *tdb, unsigned flag)
 388 {
 389         if (tdb->flags & TDB_INTERNAL) {
 390                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 391                                              TDB_LOG_USE_ERROR,
 392                                              "tdb_remove_flag: internal db");
 393                 return;
 394         }
 395         switch (flag) {
 396         case TDB_NOLOCK:
 397                 tdb->flags &= ~TDB_NOLOCK;
 398                 break;
 399         case TDB_NOMMAP:
 400                 tdb->flags &= ~TDB_NOMMAP;
 401                 tdb_mmap(tdb);
 402                 break;
 403         case TDB_NOSYNC:
 404                 tdb->flags &= ~TDB_NOSYNC;
 405                 break;
 406         case TDB_SEQNUM:
 407                 tdb->flags &= ~TDB_SEQNUM;
 408                 break;
 409         case TDB_ALLOW_NESTING:
 410                 tdb->flags &= ~TDB_ALLOW_NESTING;
 411                 break;
 412         case TDB_RDONLY:
 413                 if ((tdb->open_flags & O_ACCMODE) == O_RDONLY) {
 414                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 415                                                      TDB_LOG_USE_ERROR,
 416                                                      "tdb_remove_flag: can't"
 417                                                      " remove TDB_RDONLY on tdb"
 418                                                      " opened with O_RDONLY");
 419                         break;
 420                 }
 421                 if (readonly_changable(tdb, "tdb_remove_flag"))
 422                         tdb->flags &= ~TDB_RDONLY;
 423                 break;
 424         default:
 425                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_EINVAL,
 426                                              TDB_LOG_USE_ERROR,
 427                                              "tdb_remove_flag: Unknown flag %u",
 428                                              flag);
 429         }
 430 }
 431
 432 const char *tdb_errorstr(enum TDB_ERROR ecode)
 433 {
 434         /* Gcc warns if you miss a case in the switch, so use that. */
 435         switch (ecode) {
 436         case TDB_SUCCESS: return "Success";
 437         case TDB_ERR_CORRUPT: return "Corrupt database";
 438         case TDB_ERR_IO: return "IO Error";
 439         case TDB_ERR_LOCK: return "Locking error";
 440         case TDB_ERR_OOM: return "Out of memory";
 441         case TDB_ERR_EXISTS: return "Record exists";
 442         case TDB_ERR_EINVAL: return "Invalid parameter";
 443         case TDB_ERR_NOEXIST: return "Record does not exist";
 444         case TDB_ERR_RDONLY: return "write not permitted";
 445         }
 446         return "Invalid error code";
 447 }
 448
 449 enum TDB_ERROR tdb_error(struct tdb_context *tdb)
 450 {
 451         return tdb->last_error;
 452 }
 453
 454 enum TDB_ERROR COLD tdb_logerr(struct tdb_context *tdb,
 455                                enum TDB_ERROR ecode,
 456                                enum tdb_log_level level,
 457                                const char *fmt, ...)
 458 {
 459         char *message;
 460         va_list ap;
 461         size_t len;
 462         /* tdb_open paths care about errno, so save it. */
 463         int saved_errno = errno;
 464
 465         if (!tdb->log_fn)
 466                 return ecode;
 467
 468         va_start(ap, fmt);
 469         len = vasprintf(&message, fmt, ap);
 470         va_end(ap);
 471
 472         if (len < 0) {
 473                 tdb->log_fn(tdb, TDB_LOG_ERROR, TDB_ERR_OOM,
 474                             "out of memory formatting message:", tdb->log_data);
 475                 tdb->log_fn(tdb, level, ecode, fmt, tdb->log_data);
 476         } else {
 477                 tdb->log_fn(tdb, level, ecode, message, tdb->log_data);
 478                 free(message);
 479         }
 480         errno = saved_errno;
 481         return ecode;
 482 }
 483
 484 enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb,
 485                                  TDB_DATA key,
 486                                  enum TDB_ERROR (*parse)(TDB_DATA k,
 487                                                          TDB_DATA d,
 488                                                          void *data),
 489                                  void *data)
 490 {
 491         tdb_off_t off;
 492         struct tdb_used_record rec;
 493         struct hash_info h;
 494         enum TDB_ERROR ecode;
 495
 496         off = find_and_lock(tdb, key, F_RDLCK, &h, &rec, NULL);
 497         if (TDB_OFF_IS_ERR(off)) {
 498                 return tdb->last_error = off;
 499         }
 500
 501         if (!off) {
 502                 ecode = TDB_ERR_NOEXIST;
 503         } else {
 504                 const void *dptr;
 505                 dptr = tdb_access_read(tdb, off + sizeof(rec) + key.dsize,
 506                                        rec_data_length(&rec), false);
 507                 if (TDB_PTR_IS_ERR(dptr)) {
 508                         ecode = TDB_PTR_ERR(dptr);
 509                 } else {
 510                         TDB_DATA d = tdb_mkdata(dptr, rec_data_length(&rec));
 511
 512                         ecode = parse(key, d, data);
 513                         tdb_access_release(tdb, dptr);
 514                 }
 515         }
 516
 517         tdb_unlock_hashes(tdb, h.hlock_start, h.hlock_range, F_RDLCK);
 518         return tdb->last_error = ecode;
 519 }
 520
 521 const char *tdb_name(const struct tdb_context *tdb)
 522 {
 523         return tdb->name;
 524 }
 525
 526 int64_t tdb_get_seqnum(struct tdb_context *tdb)
 527 {
 528         tdb_off_t off = tdb_read_off(tdb, offsetof(struct tdb_header, seqnum));
 529         if (TDB_OFF_IS_ERR(off))
 530                 tdb->last_error = off;
 531         else
 532                 tdb->last_error = TDB_SUCCESS;
 533         return off;
 534 }
 535
 536
 537 int tdb_fd(const struct tdb_context *tdb)
 538 {
 539         return tdb->file->fd;
 540 }