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