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                 rec->u.ref.update_index += ti->r->min_update_index;
 243         }
 244
 245         return res;
 246 }
 247
 248 static void table_iter_block_done(struct table_iter *ti)
 249 {
 250         if (!ti->bi.br) {
 251                 return;
 252         }
 253         reftable_block_done(&ti->bi.br->block);
 254         FREE_AND_NULL(ti->bi.br);
 255
 256         ti->bi.last_key.len = 0;
 257         ti->bi.next_off = 0;
 258 }
 259
 260 static int32_t extract_block_size(uint8_t *data, uint8_t *typ, uint64_t off,
 261                                   int version)
 262 {
 263         int32_t result = 0;
 264
 265         if (off == 0) {
 266                 data += header_size(version);
 267         }
 268
 269         *typ = data[0];
 270         if (reftable_is_block_type(*typ)) {
 271                 result = get_be24(data + 1);
 272         }
 273         return result;
 274 }
 275
 276 int reader_init_block_reader(struct reftable_reader *r, struct block_reader *br,
 277                              uint64_t next_off, uint8_t want_typ)
 278 {
 279         int32_t guess_block_size = r->block_size ? r->block_size :
 280                                                          DEFAULT_BLOCK_SIZE;
 281         struct reftable_block block = { NULL };
 282         uint8_t block_typ = 0;
 283         int err = 0;
 284         uint32_t header_off = next_off ? 0 : header_size(r->version);
 285         int32_t block_size = 0;
 286
 287         if (next_off >= r->size)
 288                 return 1;
 289
 290         err = reader_get_block(r, &block, next_off, guess_block_size);
 291         if (err < 0)
 292                 goto done;
 293
 294         block_size = extract_block_size(block.data, &block_typ, next_off,
 295                                         r->version);
 296         if (block_size < 0) {
 297                 err = block_size;
 298                 goto done;
 299         }
 300         if (want_typ != BLOCK_TYPE_ANY && block_typ != want_typ) {
 301                 err = 1;
 302                 goto done;
 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                         goto done;
 310                 }
 311         }
 312
 313         err = block_reader_init(br, &block, header_off, r->block_size,
 314                                 hash_size(r->hash_id));
 315 done:
 316         reftable_block_done(&block);
 317
 318         return err;
 319 }
 320
 321 static int table_iter_next_block(struct table_iter *dest,
 322                                  struct table_iter *src)
 323 {
 324         uint64_t next_block_off = src->block_off + src->bi.br->full_block_size;
 325         struct block_reader br = { 0 };
 326         int err = 0;
 327
 328         dest->r = src->r;
 329         dest->typ = src->typ;
 330         dest->block_off = next_block_off;
 331
 332         err = reader_init_block_reader(src->r, &br, next_block_off, src->typ);
 333         if (err > 0) {
 334                 dest->is_finished = 1;
 335                 return 1;
 336         }
 337         if (err != 0)
 338                 return err;
 339         else {
 340                 struct block_reader *brp =
 341                         reftable_malloc(sizeof(struct block_reader));
 342                 *brp = br;
 343
 344                 dest->is_finished = 0;
 345                 block_reader_start(brp, &dest->bi);
 346         }
 347         return 0;
 348 }
 349
 350 static int table_iter_next(struct table_iter *ti, struct reftable_record *rec)
 351 {
 352         if (reftable_record_type(rec) != ti->typ)
 353                 return REFTABLE_API_ERROR;
 354
 355         while (1) {
 356                 struct table_iter next = TABLE_ITER_INIT;
 357                 int err = 0;
 358                 if (ti->is_finished) {
 359                         return 1;
 360                 }
 361
 362                 err = table_iter_next_in_block(ti, rec);
 363                 if (err <= 0) {
 364                         return err;
 365                 }
 366
 367                 err = table_iter_next_block(&next, ti);
 368                 if (err != 0) {
 369                         ti->is_finished = 1;
 370                 }
 371                 table_iter_block_done(ti);
 372                 if (err != 0) {
 373                         return err;
 374                 }
 375                 table_iter_copy_from(ti, &next);
 376                 block_iter_close(&next.bi);
 377         }
 378 }
 379
 380 static int table_iter_next_void(void *ti, struct reftable_record *rec)
 381 {
 382         return table_iter_next(ti, rec);
 383 }
 384
 385 static void table_iter_close(void *p)
 386 {
 387         struct table_iter *ti = p;
 388         table_iter_block_done(ti);
 389         block_iter_close(&ti->bi);
 390 }
 391
 392 static struct reftable_iterator_vtable table_iter_vtable = {
 393         .next = &table_iter_next_void,
 394         .close = &table_iter_close,
 395 };
 396
 397 static void iterator_from_table_iter(struct reftable_iterator *it,
 398                                      struct table_iter *ti)
 399 {
 400         assert(!it->ops);
 401         it->iter_arg = ti;
 402         it->ops = &table_iter_vtable;
 403 }
 404
 405 static int reader_table_iter_at(struct reftable_reader *r,
 406                                 struct table_iter *ti, uint64_t off,
 407                                 uint8_t typ)
 408 {
 409         struct block_reader br = { 0 };
 410         struct block_reader *brp = NULL;
 411
 412         int err = reader_init_block_reader(r, &br, off, typ);
 413         if (err != 0)
 414                 return err;
 415
 416         brp = reftable_malloc(sizeof(struct block_reader));
 417         *brp = br;
 418         ti->r = r;
 419         ti->typ = block_reader_type(brp);
 420         ti->block_off = off;
 421         block_reader_start(brp, &ti->bi);
 422         return 0;
 423 }
 424
 425 static int reader_start(struct reftable_reader *r, struct table_iter *ti,
 426                         uint8_t typ, int index)
 427 {
 428         struct reftable_reader_offsets *offs = reader_offsets_for(r, typ);
 429         uint64_t off = offs->offset;
 430         if (index) {
 431                 off = offs->index_offset;
 432                 if (off == 0) {
 433                         return 1;
 434                 }
 435                 typ = BLOCK_TYPE_INDEX;
 436         }
 437
 438         return reader_table_iter_at(r, ti, off, typ);
 439 }
 440
 441 static int reader_seek_linear(struct reftable_reader *r, struct table_iter *ti,
 442                               struct reftable_record *want)
 443 {
 444         struct reftable_record rec =
 445                 reftable_new_record(reftable_record_type(want));
 446         struct strbuf want_key = STRBUF_INIT;
 447         struct strbuf got_key = STRBUF_INIT;
 448         struct table_iter next = TABLE_ITER_INIT;
 449         int err = -1;
 450
 451         reftable_record_key(want, &want_key);
 452
 453         while (1) {
 454                 err = table_iter_next_block(&next, ti);
 455                 if (err < 0)
 456                         goto done;
 457
 458                 if (err > 0) {
 459                         break;
 460                 }
 461
 462                 err = block_reader_first_key(next.bi.br, &got_key);
 463                 if (err < 0)
 464                         goto done;
 465
 466                 if (strbuf_cmp(&got_key, &want_key) > 0) {
 467                         table_iter_block_done(&next);
 468                         break;
 469                 }
 470
 471                 table_iter_block_done(ti);
 472                 table_iter_copy_from(ti, &next);
 473         }
 474
 475         err = block_iter_seek(&ti->bi, &want_key);
 476         if (err < 0)
 477                 goto done;
 478         err = 0;
 479
 480 done:
 481         block_iter_close(&next.bi);
 482         reftable_record_release(&rec);
 483         strbuf_release(&want_key);
 484         strbuf_release(&got_key);
 485         return err;
 486 }
 487
 488 static int reader_seek_indexed(struct reftable_reader *r,
 489                                struct reftable_iterator *it,
 490                                struct reftable_record *rec)
 491 {
 492         struct reftable_record want_index = {
 493                 .type = BLOCK_TYPE_INDEX, .u.idx = { .last_key = STRBUF_INIT }
 494         };
 495         struct reftable_record index_result = {
 496                 .type = BLOCK_TYPE_INDEX,
 497                 .u.idx = { .last_key = STRBUF_INIT },
 498         };
 499         struct table_iter index_iter = TABLE_ITER_INIT;
 500         struct table_iter next = TABLE_ITER_INIT;
 501         int err = 0;
 502
 503         reftable_record_key(rec, &want_index.u.idx.last_key);
 504         err = reader_start(r, &index_iter, reftable_record_type(rec), 1);
 505         if (err < 0)
 506                 goto done;
 507
 508         err = reader_seek_linear(r, &index_iter, &want_index);
 509         while (1) {
 510                 err = table_iter_next(&index_iter, &index_result);
 511                 table_iter_block_done(&index_iter);
 512                 if (err != 0)
 513                         goto done;
 514
 515                 err = reader_table_iter_at(r, &next, index_result.u.idx.offset,
 516                                            0);
 517                 if (err != 0)
 518                         goto done;
 519
 520                 err = block_iter_seek(&next.bi, &want_index.u.idx.last_key);
 521                 if (err < 0)
 522                         goto done;
 523
 524                 if (next.typ == reftable_record_type(rec)) {
 525                         err = 0;
 526                         break;
 527                 }
 528
 529                 if (next.typ != BLOCK_TYPE_INDEX) {
 530                         err = REFTABLE_FORMAT_ERROR;
 531                         break;
 532                 }
 533
 534                 table_iter_copy_from(&index_iter, &next);
 535         }
 536
 537         if (err == 0) {
 538                 struct table_iter empty = TABLE_ITER_INIT;
 539                 struct table_iter *malloced =
 540                         reftable_calloc(sizeof(struct table_iter));
 541                 *malloced = empty;
 542                 table_iter_copy_from(malloced, &next);
 543                 iterator_from_table_iter(it, malloced);
 544         }
 545 done:
 546         block_iter_close(&next.bi);
 547         table_iter_close(&index_iter);
 548         reftable_record_release(&want_index);
 549         reftable_record_release(&index_result);
 550         return err;
 551 }
 552
 553 static int reader_seek_internal(struct reftable_reader *r,
 554                                 struct reftable_iterator *it,
 555                                 struct reftable_record *rec)
 556 {
 557         struct reftable_reader_offsets *offs =
 558                 reader_offsets_for(r, reftable_record_type(rec));
 559         uint64_t idx = offs->index_offset;
 560         struct table_iter ti = TABLE_ITER_INIT;
 561         int err = 0;
 562         if (idx > 0)
 563                 return reader_seek_indexed(r, it, rec);
 564
 565         err = reader_start(r, &ti, reftable_record_type(rec), 0);
 566         if (err < 0)
 567                 return err;
 568         err = reader_seek_linear(r, &ti, rec);
 569         if (err < 0)
 570                 return err;
 571         else {
 572                 struct table_iter *p =
 573                         reftable_malloc(sizeof(struct table_iter));
 574                 *p = ti;
 575                 iterator_from_table_iter(it, p);
 576         }
 577
 578         return 0;
 579 }
 580
 581 static int reader_seek(struct reftable_reader *r, struct reftable_iterator *it,
 582                        struct reftable_record *rec)
 583 {
 584         uint8_t typ = reftable_record_type(rec);
 585
 586         struct reftable_reader_offsets *offs = reader_offsets_for(r, typ);
 587         if (!offs->is_present) {
 588                 iterator_set_empty(it);
 589                 return 0;
 590         }
 591
 592         return reader_seek_internal(r, it, rec);
 593 }
 594
 595 int reftable_reader_seek_ref(struct reftable_reader *r,
 596                              struct reftable_iterator *it, const char *name)
 597 {
 598         struct reftable_record rec = {
 599                 .type = BLOCK_TYPE_REF,
 600                 .u.ref = {
 601                         .refname = (char *)name,
 602                 },
 603         };
 604         return reader_seek(r, it, &rec);
 605 }
 606
 607 int reftable_reader_seek_log_at(struct reftable_reader *r,
 608                                 struct reftable_iterator *it, const char *name,
 609                                 uint64_t update_index)
 610 {
 611         struct reftable_record rec = { .type = BLOCK_TYPE_LOG,
 612                                        .u.log = {
 613                                                .refname = (char *)name,
 614                                                .update_index = update_index,
 615                                        } };
 616         return reader_seek(r, it, &rec);
 617 }
 618
 619 int reftable_reader_seek_log(struct reftable_reader *r,
 620                              struct reftable_iterator *it, const char *name)
 621 {
 622         uint64_t max = ~((uint64_t)0);
 623         return reftable_reader_seek_log_at(r, it, name, max);
 624 }
 625
 626 void reader_close(struct reftable_reader *r)
 627 {
 628         block_source_close(&r->source);
 629         FREE_AND_NULL(r->name);
 630 }
 631
 632 int reftable_new_reader(struct reftable_reader **p,
 633                         struct reftable_block_source *src, char const *name)
 634 {
 635         struct reftable_reader *rd =
 636                 reftable_calloc(sizeof(struct reftable_reader));
 637         int err = init_reader(rd, src, name);
 638         if (err == 0) {
 639                 *p = rd;
 640         } else {
 641                 block_source_close(src);
 642                 reftable_free(rd);
 643         }
 644         return err;
 645 }
 646
 647 void reftable_reader_free(struct reftable_reader *r)
 648 {
 649         if (!r)
 650                 return;
 651         reader_close(r);
 652         reftable_free(r);
 653 }
 654
 655 static int reftable_reader_refs_for_indexed(struct reftable_reader *r,
 656                                             struct reftable_iterator *it,
 657                                             uint8_t *oid)
 658 {
 659         struct reftable_record want = {
 660                 .type = BLOCK_TYPE_OBJ,
 661                 .u.obj = {
 662                         .hash_prefix = oid,
 663                         .hash_prefix_len = r->object_id_len,
 664                 },
 665         };
 666         struct reftable_iterator oit = { NULL };
 667         struct reftable_record got = {
 668                 .type = BLOCK_TYPE_OBJ,
 669                 .u.obj = { 0 },
 670         };
 671         int err = 0;
 672         struct indexed_table_ref_iter *itr = NULL;
 673
 674         /* Look through the reverse index. */
 675         err = reader_seek(r, &oit, &want);
 676         if (err != 0)
 677                 goto done;
 678
 679         /* read out the reftable_obj_record */
 680         err = iterator_next(&oit, &got);
 681         if (err < 0)
 682                 goto done;
 683
 684         if (err > 0 || memcmp(want.u.obj.hash_prefix, got.u.obj.hash_prefix,
 685                               r->object_id_len)) {
 686                 /* didn't find it; return empty iterator */
 687                 iterator_set_empty(it);
 688                 err = 0;
 689                 goto done;
 690         }
 691
 692         err = new_indexed_table_ref_iter(&itr, r, oid, hash_size(r->hash_id),
 693                                          got.u.obj.offsets,
 694                                          got.u.obj.offset_len);
 695         if (err < 0)
 696                 goto done;
 697         got.u.obj.offsets = NULL;
 698         iterator_from_indexed_table_ref_iter(it, itr);
 699
 700 done:
 701         reftable_iterator_destroy(&oit);
 702         reftable_record_release(&got);
 703         return err;
 704 }
 705
 706 static int reftable_reader_refs_for_unindexed(struct reftable_reader *r,
 707                                               struct reftable_iterator *it,
 708                                               uint8_t *oid)
 709 {
 710         struct table_iter ti_empty = TABLE_ITER_INIT;
 711         struct table_iter *ti = reftable_calloc(sizeof(struct table_iter));
 712         struct filtering_ref_iterator *filter = NULL;
 713         struct filtering_ref_iterator empty = FILTERING_REF_ITERATOR_INIT;
 714         int oid_len = hash_size(r->hash_id);
 715         int err;
 716
 717         *ti = ti_empty;
 718         err = reader_start(r, ti, BLOCK_TYPE_REF, 0);
 719         if (err < 0) {
 720                 reftable_free(ti);
 721                 return err;
 722         }
 723
 724         filter = reftable_malloc(sizeof(struct filtering_ref_iterator));
 725         *filter = empty;
 726
 727         strbuf_add(&filter->oid, oid, oid_len);
 728         reftable_table_from_reader(&filter->tab, r);
 729         filter->double_check = 0;
 730         iterator_from_table_iter(&filter->it, ti);
 731
 732         iterator_from_filtering_ref_iterator(it, filter);
 733         return 0;
 734 }
 735
 736 int reftable_reader_refs_for(struct reftable_reader *r,
 737                              struct reftable_iterator *it, uint8_t *oid)
 738 {
 739         if (r->obj_offsets.is_present)
 740                 return reftable_reader_refs_for_indexed(r, it, oid);
 741         return reftable_reader_refs_for_unindexed(r, it, oid);
 742 }
 743
 744 uint64_t reftable_reader_max_update_index(struct reftable_reader *r)
 745 {
 746         return r->max_update_index;
 747 }
 748
 749 uint64_t reftable_reader_min_update_index(struct reftable_reader *r)
 750 {
 751         return r->min_update_index;
 752 }
 753
 754 /* generic table interface. */
 755
 756 static int reftable_reader_seek_void(void *tab, struct reftable_iterator *it,
 757                                      struct reftable_record *rec)
 758 {
 759         return reader_seek(tab, it, rec);
 760 }
 761
 762 static uint32_t reftable_reader_hash_id_void(void *tab)
 763 {
 764         return reftable_reader_hash_id(tab);
 765 }
 766
 767 static uint64_t reftable_reader_min_update_index_void(void *tab)
 768 {
 769         return reftable_reader_min_update_index(tab);
 770 }
 771
 772 static uint64_t reftable_reader_max_update_index_void(void *tab)
 773 {
 774         return reftable_reader_max_update_index(tab);
 775 }
 776
 777 static struct reftable_table_vtable reader_vtable = {
 778         .seek_record = reftable_reader_seek_void,
 779         .hash_id = reftable_reader_hash_id_void,
 780         .min_update_index = reftable_reader_min_update_index_void,
 781         .max_update_index = reftable_reader_max_update_index_void,
 782 };
 783
 784 void reftable_table_from_reader(struct reftable_table *tab,
 785                                 struct reftable_reader *reader)
 786 {
 787         assert(!tab->ops);
 788         tab->ops = &reader_vtable;
 789         tab->table_arg = reader;
 790 }
 791
 792
 793 int reftable_reader_print_file(const char *tablename)
 794 {
 795         struct reftable_block_source src = { NULL };
 796         int err = reftable_block_source_from_file(&src, tablename);
 797         struct reftable_reader *r = NULL;
 798         struct reftable_table tab = { NULL };
 799         if (err < 0)
 800                 goto done;
 801
 802         err = reftable_new_reader(&r, &src, tablename);
 803         if (err < 0)
 804                 goto done;
 805
 806         reftable_table_from_reader(&tab, r);
 807         err = reftable_table_print(&tab);
 808 done:
 809         reftable_reader_free(r);
 810         return err;
 811 }