reftable/writer.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 "writer.h"
  10
  11 #include "system.h"
  12
  13 #include "block.h"
  14 #include "constants.h"
  15 #include "record.h"
  16 #include "tree.h"
  17 #include "reftable-error.h"
  18
  19 /* finishes a block, and writes it to storage */
  20 static int writer_flush_block(struct reftable_writer *w);
  21
  22 /* deallocates memory related to the index */
  23 static void writer_clear_index(struct reftable_writer *w);
  24
  25 /* finishes writing a 'r' (refs) or 'g' (reflogs) section */
  26 static int writer_finish_public_section(struct reftable_writer *w);
  27
  28 static struct reftable_block_stats *
  29 writer_reftable_block_stats(struct reftable_writer *w, uint8_t typ)
  30 {
  31         switch (typ) {
  32         case 'r':
  33                 return &w->stats.ref_stats;
  34         case 'o':
  35                 return &w->stats.obj_stats;
  36         case 'i':
  37                 return &w->stats.idx_stats;
  38         case 'g':
  39                 return &w->stats.log_stats;
  40         }
  41         abort();
  42         return NULL;
  43 }
  44
  45 /* write data, queuing the padding for the next write. Returns negative for
  46  * error. */
  47 static int padded_write(struct reftable_writer *w, uint8_t *data, size_t len,
  48                         int padding)
  49 {
  50         int n = 0;
  51         if (w->pending_padding > 0) {
  52                 uint8_t *zeroed = reftable_calloc(w->pending_padding);
  53                 int n = w->write(w->write_arg, zeroed, w->pending_padding);
  54                 if (n < 0)
  55                         return n;
  56
  57                 w->pending_padding = 0;
  58                 reftable_free(zeroed);
  59         }
  60
  61         w->pending_padding = padding;
  62         n = w->write(w->write_arg, data, len);
  63         if (n < 0)
  64                 return n;
  65         n += padding;
  66         return 0;
  67 }
  68
  69 static void options_set_defaults(struct reftable_write_options *opts)
  70 {
  71         if (opts->restart_interval == 0) {
  72                 opts->restart_interval = 16;
  73         }
  74
  75         if (opts->hash_id == 0) {
  76                 opts->hash_id = GIT_SHA1_FORMAT_ID;
  77         }
  78         if (opts->block_size == 0) {
  79                 opts->block_size = DEFAULT_BLOCK_SIZE;
  80         }
  81 }
  82
  83 static int writer_version(struct reftable_writer *w)
  84 {
  85         return (w->opts.hash_id == 0 || w->opts.hash_id == GIT_SHA1_FORMAT_ID) ?
  86                              1 :
  87                              2;
  88 }
  89
  90 static int writer_write_header(struct reftable_writer *w, uint8_t *dest)
  91 {
  92         memcpy(dest, "REFT", 4);
  93
  94         dest[4] = writer_version(w);
  95
  96         put_be24(dest + 5, w->opts.block_size);
  97         put_be64(dest + 8, w->min_update_index);
  98         put_be64(dest + 16, w->max_update_index);
  99         if (writer_version(w) == 2) {
 100                 put_be32(dest + 24, w->opts.hash_id);
 101         }
 102         return header_size(writer_version(w));
 103 }
 104
 105 static void writer_reinit_block_writer(struct reftable_writer *w, uint8_t typ)
 106 {
 107         int block_start = 0;
 108         if (w->next == 0) {
 109                 block_start = header_size(writer_version(w));
 110         }
 111
 112         strbuf_release(&w->last_key);
 113         block_writer_init(&w->block_writer_data, typ, w->block,
 114                           w->opts.block_size, block_start,
 115                           hash_size(w->opts.hash_id));
 116         w->block_writer = &w->block_writer_data;
 117         w->block_writer->restart_interval = w->opts.restart_interval;
 118 }
 119
 120 static struct strbuf reftable_empty_strbuf = STRBUF_INIT;
 121
 122 struct reftable_writer *
 123 reftable_new_writer(ssize_t (*writer_func)(void *, const void *, size_t),
 124                     void *writer_arg, struct reftable_write_options *opts)
 125 {
 126         struct reftable_writer *wp =
 127                 reftable_calloc(sizeof(struct reftable_writer));
 128         strbuf_init(&wp->block_writer_data.last_key, 0);
 129         options_set_defaults(opts);
 130         if (opts->block_size >= (1 << 24)) {
 131                 /* TODO - error return? */
 132                 abort();
 133         }
 134         wp->last_key = reftable_empty_strbuf;
 135         wp->block = reftable_calloc(opts->block_size);
 136         wp->write = writer_func;
 137         wp->write_arg = writer_arg;
 138         wp->opts = *opts;
 139         writer_reinit_block_writer(wp, BLOCK_TYPE_REF);
 140
 141         return wp;
 142 }
 143
 144 void reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,
 145                                 uint64_t max)
 146 {
 147         w->min_update_index = min;
 148         w->max_update_index = max;
 149 }
 150
 151 void reftable_writer_free(struct reftable_writer *w)
 152 {
 153         reftable_free(w->block);
 154         reftable_free(w);
 155 }
 156
 157 struct obj_index_tree_node {
 158         struct strbuf hash;
 159         uint64_t *offsets;
 160         size_t offset_len;
 161         size_t offset_cap;
 162 };
 163
 164 #define OBJ_INDEX_TREE_NODE_INIT    \
 165         {                           \
 166                 .hash = STRBUF_INIT \
 167         }
 168
 169 static int obj_index_tree_node_compare(const void *a, const void *b)
 170 {
 171         return strbuf_cmp(&((const struct obj_index_tree_node *)a)->hash,
 172                           &((const struct obj_index_tree_node *)b)->hash);
 173 }
 174
 175 static void writer_index_hash(struct reftable_writer *w, struct strbuf *hash)
 176 {
 177         uint64_t off = w->next;
 178
 179         struct obj_index_tree_node want = { .hash = *hash };
 180
 181         struct tree_node *node = tree_search(&want, &w->obj_index_tree,
 182                                              &obj_index_tree_node_compare, 0);
 183         struct obj_index_tree_node *key = NULL;
 184         if (node == NULL) {
 185                 struct obj_index_tree_node empty = OBJ_INDEX_TREE_NODE_INIT;
 186                 key = reftable_malloc(sizeof(struct obj_index_tree_node));
 187                 *key = empty;
 188
 189                 strbuf_reset(&key->hash);
 190                 strbuf_addbuf(&key->hash, hash);
 191                 tree_search((void *)key, &w->obj_index_tree,
 192                             &obj_index_tree_node_compare, 1);
 193         } else {
 194                 key = node->key;
 195         }
 196
 197         if (key->offset_len > 0 && key->offsets[key->offset_len - 1] == off) {
 198                 return;
 199         }
 200
 201         if (key->offset_len == key->offset_cap) {
 202                 key->offset_cap = 2 * key->offset_cap + 1;
 203                 key->offsets = reftable_realloc(
 204                         key->offsets, sizeof(uint64_t) * key->offset_cap);
 205         }
 206
 207         key->offsets[key->offset_len++] = off;
 208 }
 209
 210 static int writer_add_record(struct reftable_writer *w,
 211                              struct reftable_record *rec)
 212 {
 213         struct strbuf key = STRBUF_INIT;
 214         int err = -1;
 215         reftable_record_key(rec, &key);
 216         if (strbuf_cmp(&w->last_key, &key) >= 0) {
 217                 err = REFTABLE_API_ERROR;
 218                 goto done;
 219         }
 220
 221         strbuf_reset(&w->last_key);
 222         strbuf_addbuf(&w->last_key, &key);
 223         if (w->block_writer == NULL) {
 224                 writer_reinit_block_writer(w, reftable_record_type(rec));
 225         }
 226
 227         assert(block_writer_type(w->block_writer) == reftable_record_type(rec));
 228
 229         if (block_writer_add(w->block_writer, rec) == 0) {
 230                 err = 0;
 231                 goto done;
 232         }
 233
 234         err = writer_flush_block(w);
 235         if (err < 0) {
 236                 goto done;
 237         }
 238
 239         writer_reinit_block_writer(w, reftable_record_type(rec));
 240         err = block_writer_add(w->block_writer, rec);
 241         if (err < 0) {
 242                 /* we are writing into memory, so an error can only mean it
 243                  * doesn't fit. */
 244                 err = REFTABLE_ENTRY_TOO_BIG_ERROR;
 245                 goto done;
 246         }
 247
 248         err = 0;
 249 done:
 250         strbuf_release(&key);
 251         return err;
 252 }
 253
 254 int reftable_writer_add_ref(struct reftable_writer *w,
 255                             struct reftable_ref_record *ref)
 256 {
 257         struct reftable_record rec = { NULL };
 258         struct reftable_ref_record copy = *ref;
 259         int err = 0;
 260
 261         if (ref->refname == NULL)
 262                 return REFTABLE_API_ERROR;
 263         if (ref->update_index < w->min_update_index ||
 264             ref->update_index > w->max_update_index)
 265                 return REFTABLE_API_ERROR;
 266
 267         reftable_record_from_ref(&rec, &copy);
 268         copy.update_index -= w->min_update_index;
 269
 270         err = writer_add_record(w, &rec);
 271         if (err < 0)
 272                 return err;
 273
 274         if (!w->opts.skip_index_objects && reftable_ref_record_val1(ref)) {
 275                 struct strbuf h = STRBUF_INIT;
 276                 strbuf_add(&h, (char *)reftable_ref_record_val1(ref),
 277                            hash_size(w->opts.hash_id));
 278                 writer_index_hash(w, &h);
 279                 strbuf_release(&h);
 280         }
 281
 282         if (!w->opts.skip_index_objects && reftable_ref_record_val2(ref)) {
 283                 struct strbuf h = STRBUF_INIT;
 284                 strbuf_add(&h, reftable_ref_record_val2(ref),
 285                            hash_size(w->opts.hash_id));
 286                 writer_index_hash(w, &h);
 287                 strbuf_release(&h);
 288         }
 289         return 0;
 290 }
 291
 292 int reftable_writer_add_refs(struct reftable_writer *w,
 293                              struct reftable_ref_record *refs, int n)
 294 {
 295         int err = 0;
 296         int i = 0;
 297         QSORT(refs, n, reftable_ref_record_compare_name);
 298         for (i = 0; err == 0 && i < n; i++) {
 299                 err = reftable_writer_add_ref(w, &refs[i]);
 300         }
 301         return err;
 302 }
 303
 304 static int reftable_writer_add_log_verbatim(struct reftable_writer *w,
 305                                             struct reftable_log_record *log)
 306 {
 307         struct reftable_record rec = { NULL };
 308         if (w->block_writer &&
 309             block_writer_type(w->block_writer) == BLOCK_TYPE_REF) {
 310                 int err = writer_finish_public_section(w);
 311                 if (err < 0)
 312                         return err;
 313         }
 314
 315         w->next -= w->pending_padding;
 316         w->pending_padding = 0;
 317
 318         reftable_record_from_log(&rec, log);
 319         return writer_add_record(w, &rec);
 320 }
 321
 322 int reftable_writer_add_log(struct reftable_writer *w,
 323                             struct reftable_log_record *log)
 324 {
 325         char *input_log_message = NULL;
 326         struct strbuf cleaned_message = STRBUF_INIT;
 327         int err = 0;
 328
 329         if (log->value_type == REFTABLE_LOG_DELETION)
 330                 return reftable_writer_add_log_verbatim(w, log);
 331
 332         if (log->refname == NULL)
 333                 return REFTABLE_API_ERROR;
 334
 335         input_log_message = log->value.update.message;
 336         if (!w->opts.exact_log_message && log->value.update.message) {
 337                 strbuf_addstr(&cleaned_message, log->value.update.message);
 338                 while (cleaned_message.len &&
 339                        cleaned_message.buf[cleaned_message.len - 1] == '\n')
 340                         strbuf_setlen(&cleaned_message,
 341                                       cleaned_message.len - 1);
 342                 if (strchr(cleaned_message.buf, '\n')) {
 343                         /* multiple lines not allowed. */
 344                         err = REFTABLE_API_ERROR;
 345                         goto done;
 346                 }
 347                 strbuf_addstr(&cleaned_message, "\n");
 348                 log->value.update.message = cleaned_message.buf;
 349         }
 350
 351         err = reftable_writer_add_log_verbatim(w, log);
 352         log->value.update.message = input_log_message;
 353 done:
 354         strbuf_release(&cleaned_message);
 355         return err;
 356 }
 357
 358 int reftable_writer_add_logs(struct reftable_writer *w,
 359                              struct reftable_log_record *logs, int n)
 360 {
 361         int err = 0;
 362         int i = 0;
 363         QSORT(logs, n, reftable_log_record_compare_key);
 364
 365         for (i = 0; err == 0 && i < n; i++) {
 366                 err = reftable_writer_add_log(w, &logs[i]);
 367         }
 368         return err;
 369 }
 370
 371 static int writer_finish_section(struct reftable_writer *w)
 372 {
 373         uint8_t typ = block_writer_type(w->block_writer);
 374         uint64_t index_start = 0;
 375         int max_level = 0;
 376         int threshold = w->opts.unpadded ? 1 : 3;
 377         int before_blocks = w->stats.idx_stats.blocks;
 378         int err = writer_flush_block(w);
 379         int i = 0;
 380         struct reftable_block_stats *bstats = NULL;
 381         if (err < 0)
 382                 return err;
 383
 384         while (w->index_len > threshold) {
 385                 struct reftable_index_record *idx = NULL;
 386                 int idx_len = 0;
 387
 388                 max_level++;
 389                 index_start = w->next;
 390                 writer_reinit_block_writer(w, BLOCK_TYPE_INDEX);
 391
 392                 idx = w->index;
 393                 idx_len = w->index_len;
 394
 395                 w->index = NULL;
 396                 w->index_len = 0;
 397                 w->index_cap = 0;
 398                 for (i = 0; i < idx_len; i++) {
 399                         struct reftable_record rec = { NULL };
 400                         reftable_record_from_index(&rec, idx + i);
 401                         if (block_writer_add(w->block_writer, &rec) == 0) {
 402                                 continue;
 403                         }
 404
 405                         err = writer_flush_block(w);
 406                         if (err < 0)
 407                                 return err;
 408
 409                         writer_reinit_block_writer(w, BLOCK_TYPE_INDEX);
 410
 411                         err = block_writer_add(w->block_writer, &rec);
 412                         if (err != 0) {
 413                                 /* write into fresh block should always succeed
 414                                  */
 415                                 abort();
 416                         }
 417                 }
 418                 for (i = 0; i < idx_len; i++) {
 419                         strbuf_release(&idx[i].last_key);
 420                 }
 421                 reftable_free(idx);
 422         }
 423
 424         writer_clear_index(w);
 425
 426         err = writer_flush_block(w);
 427         if (err < 0)
 428                 return err;
 429
 430         bstats = writer_reftable_block_stats(w, typ);
 431         bstats->index_blocks = w->stats.idx_stats.blocks - before_blocks;
 432         bstats->index_offset = index_start;
 433         bstats->max_index_level = max_level;
 434
 435         /* Reinit lastKey, as the next section can start with any key. */
 436         w->last_key.len = 0;
 437
 438         return 0;
 439 }
 440
 441 struct common_prefix_arg {
 442         struct strbuf *last;
 443         int max;
 444 };
 445
 446 static void update_common(void *void_arg, void *key)
 447 {
 448         struct common_prefix_arg *arg = void_arg;
 449         struct obj_index_tree_node *entry = key;
 450         if (arg->last) {
 451                 int n = common_prefix_size(&entry->hash, arg->last);
 452                 if (n > arg->max) {
 453                         arg->max = n;
 454                 }
 455         }
 456         arg->last = &entry->hash;
 457 }
 458
 459 struct write_record_arg {
 460         struct reftable_writer *w;
 461         int err;
 462 };
 463
 464 static void write_object_record(void *void_arg, void *key)
 465 {
 466         struct write_record_arg *arg = void_arg;
 467         struct obj_index_tree_node *entry = key;
 468         struct reftable_obj_record obj_rec = {
 469                 .hash_prefix = (uint8_t *)entry->hash.buf,
 470                 .hash_prefix_len = arg->w->stats.object_id_len,
 471                 .offsets = entry->offsets,
 472                 .offset_len = entry->offset_len,
 473         };
 474         struct reftable_record rec = { NULL };
 475         if (arg->err < 0)
 476                 goto done;
 477
 478         reftable_record_from_obj(&rec, &obj_rec);
 479         arg->err = block_writer_add(arg->w->block_writer, &rec);
 480         if (arg->err == 0)
 481                 goto done;
 482
 483         arg->err = writer_flush_block(arg->w);
 484         if (arg->err < 0)
 485                 goto done;
 486
 487         writer_reinit_block_writer(arg->w, BLOCK_TYPE_OBJ);
 488         arg->err = block_writer_add(arg->w->block_writer, &rec);
 489         if (arg->err == 0)
 490                 goto done;
 491         obj_rec.offset_len = 0;
 492         arg->err = block_writer_add(arg->w->block_writer, &rec);
 493
 494         /* Should be able to write into a fresh block. */
 495         assert(arg->err == 0);
 496
 497 done:;
 498 }
 499
 500 static void object_record_free(void *void_arg, void *key)
 501 {
 502         struct obj_index_tree_node *entry = key;
 503
 504         FREE_AND_NULL(entry->offsets);
 505         strbuf_release(&entry->hash);
 506         reftable_free(entry);
 507 }
 508
 509 static int writer_dump_object_index(struct reftable_writer *w)
 510 {
 511         struct write_record_arg closure = { .w = w };
 512         struct common_prefix_arg common = { NULL };
 513         if (w->obj_index_tree) {
 514                 infix_walk(w->obj_index_tree, &update_common, &common);
 515         }
 516         w->stats.object_id_len = common.max + 1;
 517
 518         writer_reinit_block_writer(w, BLOCK_TYPE_OBJ);
 519
 520         if (w->obj_index_tree) {
 521                 infix_walk(w->obj_index_tree, &write_object_record, &closure);
 522         }
 523
 524         if (closure.err < 0)
 525                 return closure.err;
 526         return writer_finish_section(w);
 527 }
 528
 529 static int writer_finish_public_section(struct reftable_writer *w)
 530 {
 531         uint8_t typ = 0;
 532         int err = 0;
 533
 534         if (w->block_writer == NULL)
 535                 return 0;
 536
 537         typ = block_writer_type(w->block_writer);
 538         err = writer_finish_section(w);
 539         if (err < 0)
 540                 return err;
 541         if (typ == BLOCK_TYPE_REF && !w->opts.skip_index_objects &&
 542             w->stats.ref_stats.index_blocks > 0) {
 543                 err = writer_dump_object_index(w);
 544                 if (err < 0)
 545                         return err;
 546         }
 547
 548         if (w->obj_index_tree) {
 549                 infix_walk(w->obj_index_tree, &object_record_free, NULL);
 550                 tree_free(w->obj_index_tree);
 551                 w->obj_index_tree = NULL;
 552         }
 553
 554         w->block_writer = NULL;
 555         return 0;
 556 }
 557
 558 int reftable_writer_close(struct reftable_writer *w)
 559 {
 560         uint8_t footer[72];
 561         uint8_t *p = footer;
 562         int err = writer_finish_public_section(w);
 563         int empty_table = w->next == 0;
 564         if (err != 0)
 565                 goto done;
 566         w->pending_padding = 0;
 567         if (empty_table) {
 568                 /* Empty tables need a header anyway. */
 569                 uint8_t header[28];
 570                 int n = writer_write_header(w, header);
 571                 err = padded_write(w, header, n, 0);
 572                 if (err < 0)
 573                         goto done;
 574         }
 575
 576         p += writer_write_header(w, footer);
 577         put_be64(p, w->stats.ref_stats.index_offset);
 578         p += 8;
 579         put_be64(p, (w->stats.obj_stats.offset) << 5 | w->stats.object_id_len);
 580         p += 8;
 581         put_be64(p, w->stats.obj_stats.index_offset);
 582         p += 8;
 583
 584         put_be64(p, w->stats.log_stats.offset);
 585         p += 8;
 586         put_be64(p, w->stats.log_stats.index_offset);
 587         p += 8;
 588
 589         put_be32(p, crc32(0, footer, p - footer));
 590         p += 4;
 591
 592         err = padded_write(w, footer, footer_size(writer_version(w)), 0);
 593         if (err < 0)
 594                 goto done;
 595
 596         if (empty_table) {
 597                 err = REFTABLE_EMPTY_TABLE_ERROR;
 598                 goto done;
 599         }
 600
 601 done:
 602         /* free up memory. */
 603         block_writer_release(&w->block_writer_data);
 604         writer_clear_index(w);
 605         strbuf_release(&w->last_key);
 606         return err;
 607 }
 608
 609 static void writer_clear_index(struct reftable_writer *w)
 610 {
 611         int i = 0;
 612         for (i = 0; i < w->index_len; i++) {
 613                 strbuf_release(&w->index[i].last_key);
 614         }
 615
 616         FREE_AND_NULL(w->index);
 617         w->index_len = 0;
 618         w->index_cap = 0;
 619 }
 620
 621 static const int debug = 0;
 622
 623 static int writer_flush_nonempty_block(struct reftable_writer *w)
 624 {
 625         uint8_t typ = block_writer_type(w->block_writer);
 626         struct reftable_block_stats *bstats =
 627                 writer_reftable_block_stats(w, typ);
 628         uint64_t block_typ_off = (bstats->blocks == 0) ? w->next : 0;
 629         int raw_bytes = block_writer_finish(w->block_writer);
 630         int padding = 0;
 631         int err = 0;
 632         struct reftable_index_record ir = { .last_key = STRBUF_INIT };
 633         if (raw_bytes < 0)
 634                 return raw_bytes;
 635
 636         if (!w->opts.unpadded && typ != BLOCK_TYPE_LOG) {
 637                 padding = w->opts.block_size - raw_bytes;
 638         }
 639
 640         if (block_typ_off > 0) {
 641                 bstats->offset = block_typ_off;
 642         }
 643
 644         bstats->entries += w->block_writer->entries;
 645         bstats->restarts += w->block_writer->restart_len;
 646         bstats->blocks++;
 647         w->stats.blocks++;
 648
 649         if (debug) {
 650                 fprintf(stderr, "block %c off %" PRIu64 " sz %d (%d)\n", typ,
 651                         w->next, raw_bytes,
 652                         get_be24(w->block + w->block_writer->header_off + 1));
 653         }
 654
 655         if (w->next == 0) {
 656                 writer_write_header(w, w->block);
 657         }
 658
 659         err = padded_write(w, w->block, raw_bytes, padding);
 660         if (err < 0)
 661                 return err;
 662
 663         if (w->index_cap == w->index_len) {
 664                 w->index_cap = 2 * w->index_cap + 1;
 665                 w->index = reftable_realloc(
 666                         w->index,
 667                         sizeof(struct reftable_index_record) * w->index_cap);
 668         }
 669
 670         ir.offset = w->next;
 671         strbuf_reset(&ir.last_key);
 672         strbuf_addbuf(&ir.last_key, &w->block_writer->last_key);
 673         w->index[w->index_len] = ir;
 674
 675         w->index_len++;
 676         w->next += padding + raw_bytes;
 677         w->block_writer = NULL;
 678         return 0;
 679 }
 680
 681 static int writer_flush_block(struct reftable_writer *w)
 682 {
 683         if (w->block_writer == NULL)
 684                 return 0;
 685         if (w->block_writer->entries == 0)
 686                 return 0;
 687         return writer_flush_nonempty_block(w);
 688 }
 689
 690 const struct reftable_stats *writer_stats(struct reftable_writer *w)
 691 {
 692         return &w->stats;
 693 }