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