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         if (!w)
 154                 return;
 155         reftable_free(w->block);
 156         reftable_free(w);
 157 }
 158
 159 struct obj_index_tree_node {
 160         struct strbuf hash;
 161         uint64_t *offsets;
 162         size_t offset_len;
 163         size_t offset_cap;
 164 };
 165
 166 #define OBJ_INDEX_TREE_NODE_INIT    \
 167         {                           \
 168                 .hash = STRBUF_INIT \
 169         }
 170
 171 static int obj_index_tree_node_compare(const void *a, const void *b)
 172 {
 173         return strbuf_cmp(&((const struct obj_index_tree_node *)a)->hash,
 174                           &((const struct obj_index_tree_node *)b)->hash);
 175 }
 176
 177 static void writer_index_hash(struct reftable_writer *w, struct strbuf *hash)
 178 {
 179         uint64_t off = w->next;
 180
 181         struct obj_index_tree_node want = { .hash = *hash };
 182
 183         struct tree_node *node = tree_search(&want, &w->obj_index_tree,
 184                                              &obj_index_tree_node_compare, 0);
 185         struct obj_index_tree_node *key = NULL;
 186         if (node == NULL) {
 187                 struct obj_index_tree_node empty = OBJ_INDEX_TREE_NODE_INIT;
 188                 key = reftable_malloc(sizeof(struct obj_index_tree_node));
 189                 *key = empty;
 190
 191                 strbuf_reset(&key->hash);
 192                 strbuf_addbuf(&key->hash, hash);
 193                 tree_search((void *)key, &w->obj_index_tree,
 194                             &obj_index_tree_node_compare, 1);
 195         } else {
 196                 key = node->key;
 197         }
 198
 199         if (key->offset_len > 0 && key->offsets[key->offset_len - 1] == off) {
 200                 return;
 201         }
 202
 203         if (key->offset_len == key->offset_cap) {
 204                 key->offset_cap = 2 * key->offset_cap + 1;
 205                 key->offsets = reftable_realloc(
 206                         key->offsets, sizeof(uint64_t) * key->offset_cap);
 207         }
 208
 209         key->offsets[key->offset_len++] = off;
 210 }
 211
 212 static int writer_add_record(struct reftable_writer *w,
 213                              struct reftable_record *rec)
 214 {
 215         struct strbuf key = STRBUF_INIT;
 216         int err = -1;
 217         reftable_record_key(rec, &key);
 218         if (strbuf_cmp(&w->last_key, &key) >= 0) {
 219                 err = REFTABLE_API_ERROR;
 220                 goto done;
 221         }
 222
 223         strbuf_reset(&w->last_key);
 224         strbuf_addbuf(&w->last_key, &key);
 225         if (w->block_writer == NULL) {
 226                 writer_reinit_block_writer(w, reftable_record_type(rec));
 227         }
 228
 229         assert(block_writer_type(w->block_writer) == reftable_record_type(rec));
 230
 231         if (block_writer_add(w->block_writer, rec) == 0) {
 232                 err = 0;
 233                 goto done;
 234         }
 235
 236         err = writer_flush_block(w);
 237         if (err < 0) {
 238                 goto done;
 239         }
 240
 241         writer_reinit_block_writer(w, reftable_record_type(rec));
 242         err = block_writer_add(w->block_writer, rec);
 243         if (err < 0) {
 244                 /* we are writing into memory, so an error can only mean it
 245                  * doesn't fit. */
 246                 err = REFTABLE_ENTRY_TOO_BIG_ERROR;
 247                 goto done;
 248         }
 249
 250         err = 0;
 251 done:
 252         strbuf_release(&key);
 253         return err;
 254 }
 255
 256 int reftable_writer_add_ref(struct reftable_writer *w,
 257                             struct reftable_ref_record *ref)
 258 {
 259         struct reftable_record rec = {
 260                 .type = BLOCK_TYPE_REF,
 261                 .u.ref = *ref,
 262         };
 263         int err = 0;
 264
 265         if (ref->refname == NULL)
 266                 return REFTABLE_API_ERROR;
 267         if (ref->update_index < w->min_update_index ||
 268             ref->update_index > w->max_update_index)
 269                 return REFTABLE_API_ERROR;
 270
 271         rec.u.ref.update_index -= w->min_update_index;
 272
 273         err = writer_add_record(w, &rec);
 274         if (err < 0)
 275                 return err;
 276
 277         if (!w->opts.skip_index_objects && reftable_ref_record_val1(ref)) {
 278                 struct strbuf h = STRBUF_INIT;
 279                 strbuf_add(&h, (char *)reftable_ref_record_val1(ref),
 280                            hash_size(w->opts.hash_id));
 281                 writer_index_hash(w, &h);
 282                 strbuf_release(&h);
 283         }
 284
 285         if (!w->opts.skip_index_objects && reftable_ref_record_val2(ref)) {
 286                 struct strbuf h = STRBUF_INIT;
 287                 strbuf_add(&h, reftable_ref_record_val2(ref),
 288                            hash_size(w->opts.hash_id));
 289                 writer_index_hash(w, &h);
 290                 strbuf_release(&h);
 291         }
 292         return 0;
 293 }
 294
 295 int reftable_writer_add_refs(struct reftable_writer *w,
 296                              struct reftable_ref_record *refs, int n)
 297 {
 298         int err = 0;
 299         int i = 0;
 300         QSORT(refs, n, reftable_ref_record_compare_name);
 301         for (i = 0; err == 0 && i < n; i++) {
 302                 err = reftable_writer_add_ref(w, &refs[i]);
 303         }
 304         return err;
 305 }
 306
 307 static int reftable_writer_add_log_verbatim(struct reftable_writer *w,
 308                                             struct reftable_log_record *log)
 309 {
 310         struct reftable_record rec = {
 311                 .type = BLOCK_TYPE_LOG,
 312                 .u.log = *log,
 313         };
 314         if (w->block_writer &&
 315             block_writer_type(w->block_writer) == BLOCK_TYPE_REF) {
 316                 int err = writer_finish_public_section(w);
 317                 if (err < 0)
 318                         return err;
 319         }
 320
 321         w->next -= w->pending_padding;
 322         w->pending_padding = 0;
 323         return writer_add_record(w, &rec);
 324 }
 325
 326 int reftable_writer_add_log(struct reftable_writer *w,
 327                             struct reftable_log_record *log)
 328 {
 329         char *input_log_message = NULL;
 330         struct strbuf cleaned_message = STRBUF_INIT;
 331         int err = 0;
 332
 333         if (log->value_type == REFTABLE_LOG_DELETION)
 334                 return reftable_writer_add_log_verbatim(w, log);
 335
 336         if (log->refname == NULL)
 337                 return REFTABLE_API_ERROR;
 338
 339         input_log_message = log->value.update.message;
 340         if (!w->opts.exact_log_message && log->value.update.message) {
 341                 strbuf_addstr(&cleaned_message, log->value.update.message);
 342                 while (cleaned_message.len &&
 343                        cleaned_message.buf[cleaned_message.len - 1] == '\n')
 344                         strbuf_setlen(&cleaned_message,
 345                                       cleaned_message.len - 1);
 346                 if (strchr(cleaned_message.buf, '\n')) {
 347                         /* multiple lines not allowed. */
 348                         err = REFTABLE_API_ERROR;
 349                         goto done;
 350                 }
 351                 strbuf_addstr(&cleaned_message, "\n");
 352                 log->value.update.message = cleaned_message.buf;
 353         }
 354
 355         err = reftable_writer_add_log_verbatim(w, log);
 356         log->value.update.message = input_log_message;
 357 done:
 358         strbuf_release(&cleaned_message);
 359         return err;
 360 }
 361
 362 int reftable_writer_add_logs(struct reftable_writer *w,
 363                              struct reftable_log_record *logs, int n)
 364 {
 365         int err = 0;
 366         int i = 0;
 367         QSORT(logs, n, reftable_log_record_compare_key);
 368
 369         for (i = 0; err == 0 && i < n; i++) {
 370                 err = reftable_writer_add_log(w, &logs[i]);
 371         }
 372         return err;
 373 }
 374
 375 static int writer_finish_section(struct reftable_writer *w)
 376 {
 377         uint8_t typ = block_writer_type(w->block_writer);
 378         uint64_t index_start = 0;
 379         int max_level = 0;
 380         int threshold = w->opts.unpadded ? 1 : 3;
 381         int before_blocks = w->stats.idx_stats.blocks;
 382         int err = writer_flush_block(w);
 383         int i = 0;
 384         struct reftable_block_stats *bstats = NULL;
 385         if (err < 0)
 386                 return err;
 387
 388         while (w->index_len > threshold) {
 389                 struct reftable_index_record *idx = NULL;
 390                 int idx_len = 0;
 391
 392                 max_level++;
 393                 index_start = w->next;
 394                 writer_reinit_block_writer(w, BLOCK_TYPE_INDEX);
 395
 396                 idx = w->index;
 397                 idx_len = w->index_len;
 398
 399                 w->index = NULL;
 400                 w->index_len = 0;
 401                 w->index_cap = 0;
 402                 for (i = 0; i < idx_len; i++) {
 403                         struct reftable_record rec = {
 404                                 .type = BLOCK_TYPE_INDEX,
 405                                 .u.idx = idx[i],
 406                         };
 407                         if (block_writer_add(w->block_writer, &rec) == 0) {
 408                                 continue;
 409                         }
 410
 411                         err = writer_flush_block(w);
 412                         if (err < 0)
 413                                 return err;
 414
 415                         writer_reinit_block_writer(w, BLOCK_TYPE_INDEX);
 416
 417                         err = block_writer_add(w->block_writer, &rec);
 418                         if (err != 0) {
 419                                 /* write into fresh block should always succeed
 420                                  */
 421                                 abort();
 422                         }
 423                 }
 424                 for (i = 0; i < idx_len; i++) {
 425                         strbuf_release(&idx[i].last_key);
 426                 }
 427                 reftable_free(idx);
 428         }
 429
 430         writer_clear_index(w);
 431
 432         err = writer_flush_block(w);
 433         if (err < 0)
 434                 return err;
 435
 436         bstats = writer_reftable_block_stats(w, typ);
 437         bstats->index_blocks = w->stats.idx_stats.blocks - before_blocks;
 438         bstats->index_offset = index_start;
 439         bstats->max_index_level = max_level;
 440
 441         /* Reinit lastKey, as the next section can start with any key. */
 442         w->last_key.len = 0;
 443
 444         return 0;
 445 }
 446
 447 struct common_prefix_arg {
 448         struct strbuf *last;
 449         int max;
 450 };
 451
 452 static void update_common(void *void_arg, void *key)
 453 {
 454         struct common_prefix_arg *arg = void_arg;
 455         struct obj_index_tree_node *entry = key;
 456         if (arg->last) {
 457                 int n = common_prefix_size(&entry->hash, arg->last);
 458                 if (n > arg->max) {
 459                         arg->max = n;
 460                 }
 461         }
 462         arg->last = &entry->hash;
 463 }
 464
 465 struct write_record_arg {
 466         struct reftable_writer *w;
 467         int err;
 468 };
 469
 470 static void write_object_record(void *void_arg, void *key)
 471 {
 472         struct write_record_arg *arg = void_arg;
 473         struct obj_index_tree_node *entry = key;
 474         struct reftable_record
 475                 rec = { .type = BLOCK_TYPE_OBJ,
 476                         .u.obj = {
 477                                 .hash_prefix = (uint8_t *)entry->hash.buf,
 478                                 .hash_prefix_len = arg->w->stats.object_id_len,
 479                                 .offsets = entry->offsets,
 480                                 .offset_len = entry->offset_len,
 481                         } };
 482         if (arg->err < 0)
 483                 goto done;
 484
 485         arg->err = block_writer_add(arg->w->block_writer, &rec);
 486         if (arg->err == 0)
 487                 goto done;
 488
 489         arg->err = writer_flush_block(arg->w);
 490         if (arg->err < 0)
 491                 goto done;
 492
 493         writer_reinit_block_writer(arg->w, BLOCK_TYPE_OBJ);
 494         arg->err = block_writer_add(arg->w->block_writer, &rec);
 495         if (arg->err == 0)
 496                 goto done;
 497
 498         rec.u.obj.offset_len = 0;
 499         arg->err = block_writer_add(arg->w->block_writer, &rec);
 500
 501         /* Should be able to write into a fresh block. */
 502         assert(arg->err == 0);
 503
 504 done:;
 505 }
 506
 507 static void object_record_free(void *void_arg, void *key)
 508 {
 509         struct obj_index_tree_node *entry = key;
 510
 511         FREE_AND_NULL(entry->offsets);
 512         strbuf_release(&entry->hash);
 513         reftable_free(entry);
 514 }
 515
 516 static int writer_dump_object_index(struct reftable_writer *w)
 517 {
 518         struct write_record_arg closure = { .w = w };
 519         struct common_prefix_arg common = { NULL };
 520         if (w->obj_index_tree) {
 521                 infix_walk(w->obj_index_tree, &update_common, &common);
 522         }
 523         w->stats.object_id_len = common.max + 1;
 524
 525         writer_reinit_block_writer(w, BLOCK_TYPE_OBJ);
 526
 527         if (w->obj_index_tree) {
 528                 infix_walk(w->obj_index_tree, &write_object_record, &closure);
 529         }
 530
 531         if (closure.err < 0)
 532                 return closure.err;
 533         return writer_finish_section(w);
 534 }
 535
 536 static int writer_finish_public_section(struct reftable_writer *w)
 537 {
 538         uint8_t typ = 0;
 539         int err = 0;
 540
 541         if (w->block_writer == NULL)
 542                 return 0;
 543
 544         typ = block_writer_type(w->block_writer);
 545         err = writer_finish_section(w);
 546         if (err < 0)
 547                 return err;
 548         if (typ == BLOCK_TYPE_REF && !w->opts.skip_index_objects &&
 549             w->stats.ref_stats.index_blocks > 0) {
 550                 err = writer_dump_object_index(w);
 551                 if (err < 0)
 552                         return err;
 553         }
 554
 555         if (w->obj_index_tree) {
 556                 infix_walk(w->obj_index_tree, &object_record_free, NULL);
 557                 tree_free(w->obj_index_tree);
 558                 w->obj_index_tree = NULL;
 559         }
 560
 561         w->block_writer = NULL;
 562         return 0;
 563 }
 564
 565 int reftable_writer_close(struct reftable_writer *w)
 566 {
 567         uint8_t footer[72];
 568         uint8_t *p = footer;
 569         int err = writer_finish_public_section(w);
 570         int empty_table = w->next == 0;
 571         if (err != 0)
 572                 goto done;
 573         w->pending_padding = 0;
 574         if (empty_table) {
 575                 /* Empty tables need a header anyway. */
 576                 uint8_t header[28];
 577                 int n = writer_write_header(w, header);
 578                 err = padded_write(w, header, n, 0);
 579                 if (err < 0)
 580                         goto done;
 581         }
 582
 583         p += writer_write_header(w, footer);
 584         put_be64(p, w->stats.ref_stats.index_offset);
 585         p += 8;
 586         put_be64(p, (w->stats.obj_stats.offset) << 5 | w->stats.object_id_len);
 587         p += 8;
 588         put_be64(p, w->stats.obj_stats.index_offset);
 589         p += 8;
 590
 591         put_be64(p, w->stats.log_stats.offset);
 592         p += 8;
 593         put_be64(p, w->stats.log_stats.index_offset);
 594         p += 8;
 595
 596         put_be32(p, crc32(0, footer, p - footer));
 597         p += 4;
 598
 599         err = padded_write(w, footer, footer_size(writer_version(w)), 0);
 600         if (err < 0)
 601                 goto done;
 602
 603         if (empty_table) {
 604                 err = REFTABLE_EMPTY_TABLE_ERROR;
 605                 goto done;
 606         }
 607
 608 done:
 609         /* free up memory. */
 610         block_writer_release(&w->block_writer_data);
 611         writer_clear_index(w);
 612         strbuf_release(&w->last_key);
 613         return err;
 614 }
 615
 616 static void writer_clear_index(struct reftable_writer *w)
 617 {
 618         int i = 0;
 619         for (i = 0; i < w->index_len; i++) {
 620                 strbuf_release(&w->index[i].last_key);
 621         }
 622
 623         FREE_AND_NULL(w->index);
 624         w->index_len = 0;
 625         w->index_cap = 0;
 626 }
 627
 628 static const int debug = 0;
 629
 630 static int writer_flush_nonempty_block(struct reftable_writer *w)
 631 {
 632         uint8_t typ = block_writer_type(w->block_writer);
 633         struct reftable_block_stats *bstats =
 634                 writer_reftable_block_stats(w, typ);
 635         uint64_t block_typ_off = (bstats->blocks == 0) ? w->next : 0;
 636         int raw_bytes = block_writer_finish(w->block_writer);
 637         int padding = 0;
 638         int err = 0;
 639         struct reftable_index_record ir = { .last_key = STRBUF_INIT };
 640         if (raw_bytes < 0)
 641                 return raw_bytes;
 642
 643         if (!w->opts.unpadded && typ != BLOCK_TYPE_LOG) {
 644                 padding = w->opts.block_size - raw_bytes;
 645         }
 646
 647         if (block_typ_off > 0) {
 648                 bstats->offset = block_typ_off;
 649         }
 650
 651         bstats->entries += w->block_writer->entries;
 652         bstats->restarts += w->block_writer->restart_len;
 653         bstats->blocks++;
 654         w->stats.blocks++;
 655
 656         if (debug) {
 657                 fprintf(stderr, "block %c off %" PRIu64 " sz %d (%d)\n", typ,
 658                         w->next, raw_bytes,
 659                         get_be24(w->block + w->block_writer->header_off + 1));
 660         }
 661
 662         if (w->next == 0) {
 663                 writer_write_header(w, w->block);
 664         }
 665
 666         err = padded_write(w, w->block, raw_bytes, padding);
 667         if (err < 0)
 668                 return err;
 669
 670         if (w->index_cap == w->index_len) {
 671                 w->index_cap = 2 * w->index_cap + 1;
 672                 w->index = reftable_realloc(
 673                         w->index,
 674                         sizeof(struct reftable_index_record) * w->index_cap);
 675         }
 676
 677         ir.offset = w->next;
 678         strbuf_reset(&ir.last_key);
 679         strbuf_addbuf(&ir.last_key, &w->block_writer->last_key);
 680         w->index[w->index_len] = ir;
 681
 682         w->index_len++;
 683         w->next += padding + raw_bytes;
 684         w->block_writer = NULL;
 685         return 0;
 686 }
 687
 688 static int writer_flush_block(struct reftable_writer *w)
 689 {
 690         if (w->block_writer == NULL)
 691                 return 0;
 692         if (w->block_writer->entries == 0)
 693                 return 0;
 694         return writer_flush_nonempty_block(w);
 695 }
 696
 697 const struct reftable_stats *writer_stats(struct reftable_writer *w)
 698 {
 699         return &w->stats;
 700 }