reftable/reader.c

   1 /*
   2 Copyright 2020 Google LLC
   3
   4 Use of this source code is governed by a BSD-style
   5 license that can be found in the LICENSE file or at
   6 https://developers.google.com/open-source/licenses/bsd
   7 */
   8
   9 #include "reader.h"
  10
  11 #include "system.h"
  12 #include "block.h"
  13 #include "constants.h"
  14 #include "generic.h"
  15 #include "iter.h"
  16 #include "record.h"
  17 #include "reftable-error.h"
  18 #include "reftable-generic.h"
  19 #include "tree.h"
  20
  21 uint64_t block_source_size(struct reftable_block_source *source)
  22 {
  23         return source->ops->size(source->arg);
  24 }
  25
  26 int block_source_read_block(struct reftable_block_source *source,
  27                             struct reftable_block *dest, uint64_t off,
  28                             uint32_t size)
  29 {
  30         int result = source->ops->read_block(source->arg, dest, off, size);
  31         dest->source = *source;
  32         return result;
  33 }
  34
  35 void block_source_close(struct reftable_block_source *source)
  36 {
  37         if (!source->ops) {
  38                 return;
  39         }
  40
  41         source->ops->close(source->arg);
  42         source->ops = NULL;
  43 }
  44
  45 static struct reftable_reader_offsets *
  46 reader_offsets_for(struct reftable_reader *r, uint8_t typ)
  47 {
  48         switch (typ) {
  49         case BLOCK_TYPE_REF:
  50                 return &r->ref_offsets;
  51         case BLOCK_TYPE_LOG:
  52                 return &r->log_offsets;
  53         case BLOCK_TYPE_OBJ:
  54                 return &r->obj_offsets;
  55         }
  56         abort();
  57 }
  58
  59 static int reader_get_block(struct reftable_reader *r,
  60                             struct reftable_block *dest, uint64_t off,
  61                             uint32_t sz)
  62 {
  63         if (off >= r->size)
  64                 return 0;
  65
  66         if (off + sz > r->size) {
  67                 sz = r->size - off;
  68         }
  69
  70         return block_source_read_block(&r->source, dest, off, sz);
  71 }
  72
  73 uint32_t reftable_reader_hash_id(struct reftable_reader *r)
  74 {
  75         return r->hash_id;
  76 }
  77
  78 const char *reader_name(struct reftable_reader *r)
  79 {
  80         return r->name;
  81 }
  82
  83 static int parse_footer(struct reftable_reader *r, uint8_t *footer,
  84                         uint8_t *header)
  85 {
  86         uint8_t *f = footer;
  87         uint8_t first_block_typ;
  88         int err = 0;
  89         uint32_t computed_crc;
  90         uint32_t file_crc;
  91
  92         if (memcmp(f, "REFT", 4)) {
  93                 err = REFTABLE_FORMAT_ERROR;
  94                 goto done;
  95         }
  96         f += 4;
  97
  98         if (memcmp(footer, header, header_size(r->version))) {
  99                 err = REFTABLE_FORMAT_ERROR;
 100                 goto done;
 101         }
 102
 103         f++;
 104         r->block_size = get_be24(f);
 105
 106         f += 3;
 107         r->min_update_index = get_be64(f);
 108         f += 8;
 109         r->max_update_index = get_be64(f);
 110         f += 8;
 111
 112         if (r->version == 1) {
 113                 r->hash_id = GIT_SHA1_FORMAT_ID;
 114         } else {
 115                 r->hash_id = get_be32(f);
 116                 switch (r->hash_id) {
 117                 case GIT_SHA1_FORMAT_ID:
 118                         break;
 119                 case GIT_SHA256_FORMAT_ID:
 120                         break;
 121                 default:
 122                         err = REFTABLE_FORMAT_ERROR;
 123                         goto done;
 124                 }
 125                 f += 4;
 126         }
 127
 128         r->ref_offsets.index_offset = get_be64(f);
 129         f += 8;
 130
 131         r->obj_offsets.offset = get_be64(f);
 132         f += 8;
 133
 134         r->object_id_len = r->obj_offsets.offset & ((1 << 5) - 1);
 135         r->obj_offsets.offset >>= 5;
 136
 137         r->obj_offsets.index_offset = get_be64(f);
 138         f += 8;
 139         r->log_offsets.offset = get_be64(f);
 140         f += 8;
 141         r->log_offsets.index_offset = get_be64(f);
 142         f += 8;
 143
 144         computed_crc = crc32(0, footer, f - footer);
 145         file_crc = get_be32(f);
 146         f += 4;
 147         if (computed_crc != file_crc) {
 148                 err = REFTABLE_FORMAT_ERROR;
 149                 goto done;
 150         }
 151
 152         first_block_typ = header[header_size(r->version)];
 153         r->ref_offsets.is_present = (first_block_typ == BLOCK_TYPE_REF);
 154         r->ref_offsets.offset = 0;
 155         r->log_offsets.is_present = (first_block_typ == BLOCK_TYPE_LOG ||
 156                                      r->log_offsets.offset > 0);
 157         r->obj_offsets.is_present = r->obj_offsets.offset > 0;
 158         err = 0;
 159 done:
 160         return err;
 161 }
 162
 163 int init_reader(struct reftable_reader *r, struct reftable_block_source *source,
 164                 const char *name)
 165 {
 166         struct reftable_block footer = { NULL };
 167         struct reftable_block header = { NULL };
 168         int err = 0;
 169         uint64_t file_size = block_source_size(source);
 170
 171         /* Need +1 to read type of first block. */
 172         uint32_t read_size = header_size(2) + 1; /* read v2 because it's larger.  */
 173         memset(r, 0, sizeof(struct reftable_reader));
 174
 175         if (read_size > file_size) {
 176                 err = REFTABLE_FORMAT_ERROR;
 177                 goto done;
 178         }
 179
 180         err = block_source_read_block(source, &header, 0, read_size);
 181         if (err != read_size) {
 182                 err = REFTABLE_IO_ERROR;
 183                 goto done;
 184         }
 185
 186         if (memcmp(header.data, "REFT", 4)) {
 187                 err = REFTABLE_FORMAT_ERROR;
 188                 goto done;
 189         }
 190         r->version = header.data[4];
 191         if (r->version != 1 && r->version != 2) {
 192                 err = REFTABLE_FORMAT_ERROR;
 193                 goto done;
 194         }
 195
 196         r->size = file_size - footer_size(r->version);
 197         r->source = *source;
 198         r->name = xstrdup(name);
 199         r->hash_id = 0;
 200
 201         err = block_source_read_block(source, &footer, r->size,
 202                                       footer_size(r->version));
 203         if (err != footer_size(r->version)) {
 204                 err = REFTABLE_IO_ERROR;
 205                 goto done;
 206         }
 207
 208         err = parse_footer(r, footer.data, header.data);
 209 done:
 210         reftable_block_done(&footer);
 211         reftable_block_done(&header);
 212         return err;
 213 }
 214
 215 struct table_iter {
 216         struct reftable_reader *r;
 217         uint8_t typ;
 218         uint64_t block_off;
 219         struct block_iter bi;
 220         int is_finished;
 221 };
 222 #define TABLE_ITER_INIT                          \
 223         {                                        \
 224                 .bi = {.last_key = STRBUF_INIT } \
 225         }
 226
 227 static void table_iter_copy_from(struct table_iter *dest,
 228                                  struct table_iter *src)
 229 {
 230         dest->r = src->r;
 231         dest->typ = src->typ;
 232         dest->block_off = src->block_off;
 233         dest->is_finished = src->is_finished;
 234         block_iter_copy_from(&dest->bi, &src->bi);
 235 }
 236
 237 static int table_iter_next_in_block(struct table_iter *ti,
 238                                     struct reftable_record *rec)
 239 {
 240         int res = block_iter_next(&ti->bi, rec);
 241         if (res == 0 && reftable_record_type(rec) == BLOCK_TYPE_REF) {
 242                 ((struct reftable_ref_record *)rec->data)->update_index +=
 243                         ti->r->min_update_index;
 244         }
 245
 246         return res;
 247 }
 248
 249 static void table_iter_block_done(struct table_iter *ti)
 250 {
 251         if (!ti->bi.br) {
 252                 return;
 253         }
 254         reftable_block_done(&ti->bi.br->block);
 255         FREE_AND_NULL(ti->bi.br);
 256
 257         ti->bi.last_key.len = 0;
 258         ti->bi.next_off = 0;
 259 }
 260
 261 static int32_t extract_block_size(uint8_t *data, uint8_t *typ, uint64_t off,
 262                                   int version)
 263 {
 264         int32_t result = 0;
 265
 266         if (off == 0) {
 267                 data += header_size(version);
 268         }
 269
 270         *typ = data[0];
 271         if (reftable_is_block_type(*typ)) {
 272                 result = get_be24(data + 1);
 273         }
 274         return result;
 275 }
 276
 277 int reader_init_block_reader(struct reftable_reader *r, struct block_reader *br,
 278                              uint64_t next_off, uint8_t want_typ)
 279 {
 280         int32_t guess_block_size = r->block_size ? r->block_size :
 281                                                          DEFAULT_BLOCK_SIZE;
 282         struct reftable_block block = { NULL };
 283         uint8_t block_typ = 0;
 284         int err = 0;
 285         uint32_t header_off = next_off ? 0 : header_size(r->version);
 286         int32_t block_size = 0;
 287
 288         if (next_off >= r->size)
 289                 return 1;
 290
 291         err = reader_get_block(r, &block, next_off, guess_block_size);
 292         if (err < 0)
 293                 return err;
 294
 295         block_size = extract_block_size(block.data, &block_typ, next_off,
 296                                         r->version);
 297         if (block_size < 0)
 298                 return block_size;
 299
 300         if (want_typ != BLOCK_TYPE_ANY && block_typ != want_typ) {
 301                 reftable_block_done(&block);
 302                 return 1;
 303         }
 304
 305         if (block_size > guess_block_size) {
 306                 reftable_block_done(&block);
 307                 err = reader_get_block(r, &block, next_off, block_size);
 308                 if (err < 0) {
 309                         return err;
 310                 }
 311         }
 312
 313         return block_reader_init(br, &block, header_off, r->block_size,
 314                                  hash_size(r->hash_id));
 315 }
 316
 317 static int table_iter_next_block(struct table_iter *dest,
 318                                  struct table_iter *src)
 319 {
 320         uint64_t next_block_off = src->block_off + src->bi.br->full_block_size;
 321         struct block_reader br = { 0 };
 322         int err = 0;
 323
 324         dest->r = src->r;
 325         dest->typ = src->typ;
 326         dest->block_off = next_block_off;
 327
 328         err = reader_init_block_reader(src->r, &br, next_block_off, src->typ);
 329         if (err > 0) {
 330                 dest->is_finished = 1;
 331                 return 1;
 332         }
 333         if (err != 0)
 334                 return err;
 335         else {
 336                 struct block_reader *brp =
 337                         reftable_malloc(sizeof(struct block_reader));
 338                 *brp = br;
 339
 340                 dest->is_finished = 0;
 341                 block_reader_start(brp, &dest->bi);
 342         }
 343         return 0;
 344 }
 345
 346 static int table_iter_next(struct table_iter *ti, struct reftable_record *rec)
 347 {
 348         if (reftable_record_type(rec) != ti->typ)
 349                 return REFTABLE_API_ERROR;
 350
 351         while (1) {
 352                 struct table_iter next = TABLE_ITER_INIT;
 353                 int err = 0;
 354                 if (ti->is_finished) {
 355                         return 1;
 356                 }
 357
 358                 err = table_iter_next_in_block(ti, rec);
 359                 if (err <= 0) {
 360                         return err;
 361                 }
 362
 363                 err = table_iter_next_block(&next, ti);
 364                 if (err != 0) {
 365                         ti->is_finished = 1;
 366                 }
 367                 table_iter_block_done(ti);
 368                 if (err != 0) {
 369                         return err;
 370                 }
 371                 table_iter_copy_from(ti, &next);
 372                 block_iter_close(&next.bi);
 373         }
 374 }
 375
 376 static int table_iter_next_void(void *ti, struct reftable_record *rec)
 377 {
 378         return table_iter_next(ti, rec);
 379 }
 380
 381 static void table_iter_close(void *p)
 382 {
 383         struct table_iter *ti = p;
 384         table_iter_block_done(ti);
 385         block_iter_close(&ti->bi);
 386 }
 387
 388 static struct reftable_iterator_vtable table_iter_vtable = {
 389         .next = &table_iter_next_void,
 390         .close = &table_iter_close,
 391 };
 392
 393 static void iterator_from_table_iter(struct reftable_iterator *it,
 394                                      struct table_iter *ti)
 395 {
 396         assert(!it->ops);
 397         it->iter_arg = ti;
 398         it->ops = &table_iter_vtable;
 399 }
 400
 401 static int reader_table_iter_at(struct reftable_reader *r,
 402                                 struct table_iter *ti, uint64_t off,
 403                                 uint8_t typ)
 404 {
 405         struct block_reader br = { 0 };
 406         struct block_reader *brp = NULL;
 407
 408         int err = reader_init_block_reader(r, &br, off, typ);
 409         if (err != 0)
 410                 return err;
 411
 412         brp = reftable_malloc(sizeof(struct block_reader));
 413         *brp = br;
 414         ti->r = r;
 415         ti->typ = block_reader_type(brp);
 416         ti->block_off = off;
 417         block_reader_start(brp, &ti->bi);
 418         return 0;
 419 }
 420
 421 static int reader_start(struct reftable_reader *r, struct table_iter *ti,
 422                         uint8_t typ, int index)
 423 {
 424         struct reftable_reader_offsets *offs = reader_offsets_for(r, typ);
 425         uint64_t off = offs->offset;
 426         if (index) {
 427                 off = offs->index_offset;
 428                 if (off == 0) {
 429                         return 1;
 430                 }
 431                 typ = BLOCK_TYPE_INDEX;
 432         }
 433
 434         return reader_table_iter_at(r, ti, off, typ);
 435 }
 436
 437 static int reader_seek_linear(struct reftable_reader *r, struct table_iter *ti,
 438                               struct reftable_record *want)
 439 {
 440         struct reftable_record rec =
 441                 reftable_new_record(reftable_record_type(want));
 442         struct strbuf want_key = STRBUF_INIT;
 443         struct strbuf got_key = STRBUF_INIT;
 444         struct table_iter next = TABLE_ITER_INIT;
 445         int err = -1;
 446
 447         reftable_record_key(want, &want_key);
 448
 449         while (1) {
 450                 err = table_iter_next_block(&next, ti);
 451                 if (err < 0)
 452                         goto done;
 453
 454                 if (err > 0) {
 455                         break;
 456                 }
 457
 458                 err = block_reader_first_key(next.bi.br, &got_key);
 459                 if (err < 0)
 460                         goto done;
 461
 462                 if (strbuf_cmp(&got_key, &want_key) > 0) {
 463                         table_iter_block_done(&next);
 464                         break;
 465                 }
 466
 467                 table_iter_block_done(ti);
 468                 table_iter_copy_from(ti, &next);
 469         }
 470
 471         err = block_iter_seek(&ti->bi, &want_key);
 472         if (err < 0)
 473                 goto done;
 474         err = 0;
 475
 476 done:
 477         block_iter_close(&next.bi);
 478         reftable_record_destroy(&rec);
 479         strbuf_release(&want_key);
 480         strbuf_release(&got_key);
 481         return err;
 482 }
 483
 484 static int reader_seek_indexed(struct reftable_reader *r,
 485                                struct reftable_iterator *it,
 486                                struct reftable_record *rec)
 487 {
 488         struct reftable_index_record want_index = { .last_key = STRBUF_INIT };
 489         struct reftable_record want_index_rec = { NULL };
 490         struct reftable_index_record index_result = { .last_key = STRBUF_INIT };
 491         struct reftable_record index_result_rec = { NULL };
 492         struct table_iter index_iter = TABLE_ITER_INIT;
 493         struct table_iter next = TABLE_ITER_INIT;
 494         int err = 0;
 495
 496         reftable_record_key(rec, &want_index.last_key);
 497         reftable_record_from_index(&want_index_rec, &want_index);
 498         reftable_record_from_index(&index_result_rec, &index_result);
 499
 500         err = reader_start(r, &index_iter, reftable_record_type(rec), 1);
 501         if (err < 0)
 502                 goto done;
 503
 504         err = reader_seek_linear(r, &index_iter, &want_index_rec);
 505         while (1) {
 506                 err = table_iter_next(&index_iter, &index_result_rec);
 507                 table_iter_block_done(&index_iter);
 508                 if (err != 0)
 509                         goto done;
 510
 511                 err = reader_table_iter_at(r, &next, index_result.offset, 0);
 512                 if (err != 0)
 513                         goto done;
 514
 515                 err = block_iter_seek(&next.bi, &want_index.last_key);
 516                 if (err < 0)
 517                         goto done;
 518
 519                 if (next.typ == reftable_record_type(rec)) {
 520                         err = 0;
 521                         break;
 522                 }
 523
 524                 if (next.typ != BLOCK_TYPE_INDEX) {
 525                         err = REFTABLE_FORMAT_ERROR;
 526                         break;
 527                 }
 528
 529                 table_iter_copy_from(&index_iter, &next);
 530         }
 531
 532         if (err == 0) {
 533                 struct table_iter empty = TABLE_ITER_INIT;
 534                 struct table_iter *malloced =
 535                         reftable_calloc(sizeof(struct table_iter));
 536                 *malloced = empty;
 537                 table_iter_copy_from(malloced, &next);
 538                 iterator_from_table_iter(it, malloced);
 539         }
 540 done:
 541         block_iter_close(&next.bi);
 542         table_iter_close(&index_iter);
 543         reftable_record_release(&want_index_rec);
 544         reftable_record_release(&index_result_rec);
 545         return err;
 546 }
 547
 548 static int reader_seek_internal(struct reftable_reader *r,
 549                                 struct reftable_iterator *it,
 550                                 struct reftable_record *rec)
 551 {
 552         struct reftable_reader_offsets *offs =
 553                 reader_offsets_for(r, reftable_record_type(rec));
 554         uint64_t idx = offs->index_offset;
 555         struct table_iter ti = TABLE_ITER_INIT;
 556         int err = 0;
 557         if (idx > 0)
 558                 return reader_seek_indexed(r, it, rec);
 559
 560         err = reader_start(r, &ti, reftable_record_type(rec), 0);
 561         if (err < 0)
 562                 return err;
 563         err = reader_seek_linear(r, &ti, rec);
 564         if (err < 0)
 565                 return err;
 566         else {
 567                 struct table_iter *p =
 568                         reftable_malloc(sizeof(struct table_iter));
 569                 *p = ti;
 570                 iterator_from_table_iter(it, p);
 571         }
 572
 573         return 0;
 574 }
 575
 576 static int reader_seek(struct reftable_reader *r, struct reftable_iterator *it,
 577                        struct reftable_record *rec)
 578 {
 579         uint8_t typ = reftable_record_type(rec);
 580
 581         struct reftable_reader_offsets *offs = reader_offsets_for(r, typ);
 582         if (!offs->is_present) {
 583                 iterator_set_empty(it);
 584                 return 0;
 585         }
 586
 587         return reader_seek_internal(r, it, rec);
 588 }
 589
 590 int reftable_reader_seek_ref(struct reftable_reader *r,
 591                              struct reftable_iterator *it, const char *name)
 592 {
 593         struct reftable_ref_record ref = {
 594                 .refname = (char *)name,
 595         };
 596         struct reftable_record rec = { NULL };
 597         reftable_record_from_ref(&rec, &ref);
 598         return reader_seek(r, it, &rec);
 599 }
 600
 601 int reftable_reader_seek_log_at(struct reftable_reader *r,
 602                                 struct reftable_iterator *it, const char *name,
 603                                 uint64_t update_index)
 604 {
 605         struct reftable_log_record log = {
 606                 .refname = (char *)name,
 607                 .update_index = update_index,
 608         };
 609         struct reftable_record rec = { NULL };
 610         reftable_record_from_log(&rec, &log);
 611         return reader_seek(r, it, &rec);
 612 }
 613
 614 int reftable_reader_seek_log(struct reftable_reader *r,
 615                              struct reftable_iterator *it, const char *name)
 616 {
 617         uint64_t max = ~((uint64_t)0);
 618         return reftable_reader_seek_log_at(r, it, name, max);
 619 }
 620
 621 void reader_close(struct reftable_reader *r)
 622 {
 623         block_source_close(&r->source);
 624         FREE_AND_NULL(r->name);
 625 }
 626
 627 int reftable_new_reader(struct reftable_reader **p,
 628                         struct reftable_block_source *src, char const *name)
 629 {
 630         struct reftable_reader *rd =
 631                 reftable_calloc(sizeof(struct reftable_reader));
 632         int err = init_reader(rd, src, name);
 633         if (err == 0) {
 634                 *p = rd;
 635         } else {
 636                 block_source_close(src);
 637                 reftable_free(rd);
 638         }
 639         return err;
 640 }
 641
 642 void reftable_reader_free(struct reftable_reader *r)
 643 {
 644         reader_close(r);
 645         reftable_free(r);
 646 }
 647
 648 static int reftable_reader_refs_for_indexed(struct reftable_reader *r,
 649                                             struct reftable_iterator *it,
 650                                             uint8_t *oid)
 651 {
 652         struct reftable_obj_record want = {
 653                 .hash_prefix = oid,
 654                 .hash_prefix_len = r->object_id_len,
 655         };
 656         struct reftable_record want_rec = { NULL };
 657         struct reftable_iterator oit = { NULL };
 658         struct reftable_obj_record got = { NULL };
 659         struct reftable_record got_rec = { NULL };
 660         int err = 0;
 661         struct indexed_table_ref_iter *itr = NULL;
 662
 663         /* Look through the reverse index. */
 664         reftable_record_from_obj(&want_rec, &want);
 665         err = reader_seek(r, &oit, &want_rec);
 666         if (err != 0)
 667                 goto done;
 668
 669         /* read out the reftable_obj_record */
 670         reftable_record_from_obj(&got_rec, &got);
 671         err = iterator_next(&oit, &got_rec);
 672         if (err < 0)
 673                 goto done;
 674
 675         if (err > 0 ||
 676             memcmp(want.hash_prefix, got.hash_prefix, r->object_id_len)) {
 677                 /* didn't find it; return empty iterator */
 678                 iterator_set_empty(it);
 679                 err = 0;
 680                 goto done;
 681         }
 682
 683         err = new_indexed_table_ref_iter(&itr, r, oid, hash_size(r->hash_id),
 684                                          got.offsets, got.offset_len);
 685         if (err < 0)
 686                 goto done;
 687         got.offsets = NULL;
 688         iterator_from_indexed_table_ref_iter(it, itr);
 689
 690 done:
 691         reftable_iterator_destroy(&oit);
 692         reftable_record_release(&got_rec);
 693         return err;
 694 }
 695
 696 static int reftable_reader_refs_for_unindexed(struct reftable_reader *r,
 697                                               struct reftable_iterator *it,
 698                                               uint8_t *oid)
 699 {
 700         struct table_iter ti_empty = TABLE_ITER_INIT;
 701         struct table_iter *ti = reftable_calloc(sizeof(struct table_iter));
 702         struct filtering_ref_iterator *filter = NULL;
 703         struct filtering_ref_iterator empty = FILTERING_REF_ITERATOR_INIT;
 704         int oid_len = hash_size(r->hash_id);
 705         int err;
 706
 707         *ti = ti_empty;
 708         err = reader_start(r, ti, BLOCK_TYPE_REF, 0);
 709         if (err < 0) {
 710                 reftable_free(ti);
 711                 return err;
 712         }
 713
 714         filter = reftable_malloc(sizeof(struct filtering_ref_iterator));
 715         *filter = empty;
 716
 717         strbuf_add(&filter->oid, oid, oid_len);
 718         reftable_table_from_reader(&filter->tab, r);
 719         filter->double_check = 0;
 720         iterator_from_table_iter(&filter->it, ti);
 721
 722         iterator_from_filtering_ref_iterator(it, filter);
 723         return 0;
 724 }
 725
 726 int reftable_reader_refs_for(struct reftable_reader *r,
 727                              struct reftable_iterator *it, uint8_t *oid)
 728 {
 729         if (r->obj_offsets.is_present)
 730                 return reftable_reader_refs_for_indexed(r, it, oid);
 731         return reftable_reader_refs_for_unindexed(r, it, oid);
 732 }
 733
 734 uint64_t reftable_reader_max_update_index(struct reftable_reader *r)
 735 {
 736         return r->max_update_index;
 737 }
 738
 739 uint64_t reftable_reader_min_update_index(struct reftable_reader *r)
 740 {
 741         return r->min_update_index;
 742 }
 743
 744 /* generic table interface. */
 745
 746 static int reftable_reader_seek_void(void *tab, struct reftable_iterator *it,
 747                                      struct reftable_record *rec)
 748 {
 749         return reader_seek(tab, it, rec);
 750 }
 751
 752 static uint32_t reftable_reader_hash_id_void(void *tab)
 753 {
 754         return reftable_reader_hash_id(tab);
 755 }
 756
 757 static uint64_t reftable_reader_min_update_index_void(void *tab)
 758 {
 759         return reftable_reader_min_update_index(tab);
 760 }
 761
 762 static uint64_t reftable_reader_max_update_index_void(void *tab)
 763 {
 764         return reftable_reader_max_update_index(tab);
 765 }
 766
 767 static struct reftable_table_vtable reader_vtable = {
 768         .seek_record = reftable_reader_seek_void,
 769         .hash_id = reftable_reader_hash_id_void,
 770         .min_update_index = reftable_reader_min_update_index_void,
 771         .max_update_index = reftable_reader_max_update_index_void,
 772 };
 773
 774 void reftable_table_from_reader(struct reftable_table *tab,
 775                                 struct reftable_reader *reader)
 776 {
 777         assert(!tab->ops);
 778         tab->ops = &reader_vtable;
 779         tab->table_arg = reader;
 780 }
 781
 782
 783 int reftable_reader_print_file(const char *tablename)
 784 {
 785         struct reftable_block_source src = { NULL };
 786         int err = reftable_block_source_from_file(&src, tablename);
 787         struct reftable_reader *r = NULL;
 788         struct reftable_table tab = { NULL };
 789         if (err < 0)
 790                 goto done;
 791
 792         err = reftable_new_reader(&r, &src, tablename);
 793         if (err < 0)
 794                 goto done;
 795
 796         reftable_table_from_reader(&tab, r);
 797         err = reftable_table_print(&tab);
 798 done:
 799         reftable_reader_free(r);
 800         return err;
 801 }