reftable/record.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 /* record.c - methods for different types of records. */
  10
  11 #include "record.h"
  12
  13 #include "system.h"
  14 #include "constants.h"
  15 #include "reftable-error.h"
  16 #include "basics.h"
  17
  18 static struct reftable_record_vtable *
  19 reftable_record_vtable(struct reftable_record *rec);
  20 static void *reftable_record_data(struct reftable_record *rec);
  21
  22 int get_var_int(uint64_t *dest, struct string_view *in)
  23 {
  24         int ptr = 0;
  25         uint64_t val;
  26
  27         if (in->len == 0)
  28                 return -1;
  29         val = in->buf[ptr] & 0x7f;
  30
  31         while (in->buf[ptr] & 0x80) {
  32                 ptr++;
  33                 if (ptr > in->len) {
  34                         return -1;
  35                 }
  36                 val = (val + 1) << 7 | (uint64_t)(in->buf[ptr] & 0x7f);
  37         }
  38
  39         *dest = val;
  40         return ptr + 1;
  41 }
  42
  43 int put_var_int(struct string_view *dest, uint64_t val)
  44 {
  45         uint8_t buf[10] = { 0 };
  46         int i = 9;
  47         int n = 0;
  48         buf[i] = (uint8_t)(val & 0x7f);
  49         i--;
  50         while (1) {
  51                 val >>= 7;
  52                 if (!val) {
  53                         break;
  54                 }
  55                 val--;
  56                 buf[i] = 0x80 | (uint8_t)(val & 0x7f);
  57                 i--;
  58         }
  59
  60         n = sizeof(buf) - i - 1;
  61         if (dest->len < n)
  62                 return -1;
  63         memcpy(dest->buf, &buf[i + 1], n);
  64         return n;
  65 }
  66
  67 int reftable_is_block_type(uint8_t typ)
  68 {
  69         switch (typ) {
  70         case BLOCK_TYPE_REF:
  71         case BLOCK_TYPE_LOG:
  72         case BLOCK_TYPE_OBJ:
  73         case BLOCK_TYPE_INDEX:
  74                 return 1;
  75         }
  76         return 0;
  77 }
  78
  79 const unsigned char *reftable_ref_record_val1(const struct reftable_ref_record *rec)
  80 {
  81         switch (rec->value_type) {
  82         case REFTABLE_REF_VAL1:
  83                 return rec->value.val1;
  84         case REFTABLE_REF_VAL2:
  85                 return rec->value.val2.value;
  86         default:
  87                 return NULL;
  88         }
  89 }
  90
  91 const unsigned char *reftable_ref_record_val2(const struct reftable_ref_record *rec)
  92 {
  93         switch (rec->value_type) {
  94         case REFTABLE_REF_VAL2:
  95                 return rec->value.val2.target_value;
  96         default:
  97                 return NULL;
  98         }
  99 }
 100
 101 static int decode_string(struct strbuf *dest, struct string_view in)
 102 {
 103         int start_len = in.len;
 104         uint64_t tsize = 0;
 105         int n = get_var_int(&tsize, &in);
 106         if (n <= 0)
 107                 return -1;
 108         string_view_consume(&in, n);
 109         if (in.len < tsize)
 110                 return -1;
 111
 112         strbuf_reset(dest);
 113         strbuf_add(dest, in.buf, tsize);
 114         string_view_consume(&in, tsize);
 115
 116         return start_len - in.len;
 117 }
 118
 119 static int encode_string(char *str, struct string_view s)
 120 {
 121         struct string_view start = s;
 122         int l = strlen(str);
 123         int n = put_var_int(&s, l);
 124         if (n < 0)
 125                 return -1;
 126         string_view_consume(&s, n);
 127         if (s.len < l)
 128                 return -1;
 129         memcpy(s.buf, str, l);
 130         string_view_consume(&s, l);
 131
 132         return start.len - s.len;
 133 }
 134
 135 int reftable_encode_key(int *restart, struct string_view dest,
 136                         struct strbuf prev_key, struct strbuf key,
 137                         uint8_t extra)
 138 {
 139         struct string_view start = dest;
 140         int prefix_len = common_prefix_size(&prev_key, &key);
 141         uint64_t suffix_len = key.len - prefix_len;
 142         int n = put_var_int(&dest, (uint64_t)prefix_len);
 143         if (n < 0)
 144                 return -1;
 145         string_view_consume(&dest, n);
 146
 147         *restart = (prefix_len == 0);
 148
 149         n = put_var_int(&dest, suffix_len << 3 | (uint64_t)extra);
 150         if (n < 0)
 151                 return -1;
 152         string_view_consume(&dest, n);
 153
 154         if (dest.len < suffix_len)
 155                 return -1;
 156         memcpy(dest.buf, key.buf + prefix_len, suffix_len);
 157         string_view_consume(&dest, suffix_len);
 158
 159         return start.len - dest.len;
 160 }
 161
 162 int reftable_decode_key(struct strbuf *last_key, uint8_t *extra,
 163                         struct string_view in)
 164 {
 165         int start_len = in.len;
 166         uint64_t prefix_len = 0;
 167         uint64_t suffix_len = 0;
 168         int n;
 169
 170         n = get_var_int(&prefix_len, &in);
 171         if (n < 0)
 172                 return -1;
 173         string_view_consume(&in, n);
 174
 175         n = get_var_int(&suffix_len, &in);
 176         if (n <= 0)
 177                 return -1;
 178         string_view_consume(&in, n);
 179
 180         *extra = (uint8_t)(suffix_len & 0x7);
 181         suffix_len >>= 3;
 182
 183         if (in.len < suffix_len ||
 184             prefix_len > last_key->len)
 185                 return -1;
 186
 187         strbuf_setlen(last_key, prefix_len);
 188         strbuf_add(last_key, in.buf, suffix_len);
 189         string_view_consume(&in, suffix_len);
 190
 191         return start_len - in.len;
 192 }
 193
 194 static void reftable_ref_record_key(const void *r, struct strbuf *dest)
 195 {
 196         const struct reftable_ref_record *rec =
 197                 (const struct reftable_ref_record *)r;
 198         strbuf_reset(dest);
 199         strbuf_addstr(dest, rec->refname);
 200 }
 201
 202 static void reftable_ref_record_copy_from(void *rec, const void *src_rec,
 203                                           int hash_size)
 204 {
 205         struct reftable_ref_record *ref = rec;
 206         const struct reftable_ref_record *src = src_rec;
 207         char *refname = NULL;
 208         size_t refname_cap = 0;
 209
 210         assert(hash_size > 0);
 211
 212         SWAP(refname, ref->refname);
 213         SWAP(refname_cap, ref->refname_cap);
 214         reftable_ref_record_release(ref);
 215         SWAP(ref->refname, refname);
 216         SWAP(ref->refname_cap, refname_cap);
 217
 218         if (src->refname) {
 219                 size_t refname_len = strlen(src->refname);
 220
 221                 REFTABLE_ALLOC_GROW(ref->refname, refname_len + 1,
 222                                     ref->refname_cap);
 223                 memcpy(ref->refname, src->refname, refname_len);
 224                 ref->refname[refname_len] = 0;
 225         }
 226
 227         ref->update_index = src->update_index;
 228         ref->value_type = src->value_type;
 229         switch (src->value_type) {
 230         case REFTABLE_REF_DELETION:
 231                 break;
 232         case REFTABLE_REF_VAL1:
 233                 memcpy(ref->value.val1, src->value.val1, hash_size);
 234                 break;
 235         case REFTABLE_REF_VAL2:
 236                 memcpy(ref->value.val2.value, src->value.val2.value, hash_size);
 237                 memcpy(ref->value.val2.target_value,
 238                        src->value.val2.target_value, hash_size);
 239                 break;
 240         case REFTABLE_REF_SYMREF:
 241                 ref->value.symref = xstrdup(src->value.symref);
 242                 break;
 243         }
 244 }
 245
 246 static char hexdigit(int c)
 247 {
 248         if (c <= 9)
 249                 return '0' + c;
 250         return 'a' + (c - 10);
 251 }
 252
 253 static void hex_format(char *dest, const unsigned char *src, int hash_size)
 254 {
 255         assert(hash_size > 0);
 256         if (src) {
 257                 int i = 0;
 258                 for (i = 0; i < hash_size; i++) {
 259                         dest[2 * i] = hexdigit(src[i] >> 4);
 260                         dest[2 * i + 1] = hexdigit(src[i] & 0xf);
 261                 }
 262                 dest[2 * hash_size] = 0;
 263         }
 264 }
 265
 266 static void reftable_ref_record_print_sz(const struct reftable_ref_record *ref,
 267                                          int hash_size)
 268 {
 269         char hex[GIT_MAX_HEXSZ + 1] = { 0 }; /* BUG */
 270         printf("ref{%s(%" PRIu64 ") ", ref->refname, ref->update_index);
 271         switch (ref->value_type) {
 272         case REFTABLE_REF_SYMREF:
 273                 printf("=> %s", ref->value.symref);
 274                 break;
 275         case REFTABLE_REF_VAL2:
 276                 hex_format(hex, ref->value.val2.value, hash_size);
 277                 printf("val 2 %s", hex);
 278                 hex_format(hex, ref->value.val2.target_value,
 279                            hash_size);
 280                 printf("(T %s)", hex);
 281                 break;
 282         case REFTABLE_REF_VAL1:
 283                 hex_format(hex, ref->value.val1, hash_size);
 284                 printf("val 1 %s", hex);
 285                 break;
 286         case REFTABLE_REF_DELETION:
 287                 printf("delete");
 288                 break;
 289         }
 290         printf("}\n");
 291 }
 292
 293 void reftable_ref_record_print(const struct reftable_ref_record *ref,
 294                                uint32_t hash_id) {
 295         reftable_ref_record_print_sz(ref, hash_size(hash_id));
 296 }
 297
 298 static void reftable_ref_record_release_void(void *rec)
 299 {
 300         reftable_ref_record_release(rec);
 301 }
 302
 303 void reftable_ref_record_release(struct reftable_ref_record *ref)
 304 {
 305         switch (ref->value_type) {
 306         case REFTABLE_REF_SYMREF:
 307                 reftable_free(ref->value.symref);
 308                 break;
 309         case REFTABLE_REF_VAL2:
 310                 break;
 311         case REFTABLE_REF_VAL1:
 312                 break;
 313         case REFTABLE_REF_DELETION:
 314                 break;
 315         default:
 316                 abort();
 317         }
 318
 319         reftable_free(ref->refname);
 320         memset(ref, 0, sizeof(struct reftable_ref_record));
 321 }
 322
 323 static uint8_t reftable_ref_record_val_type(const void *rec)
 324 {
 325         const struct reftable_ref_record *r =
 326                 (const struct reftable_ref_record *)rec;
 327         return r->value_type;
 328 }
 329
 330 static int reftable_ref_record_encode(const void *rec, struct string_view s,
 331                                       int hash_size)
 332 {
 333         const struct reftable_ref_record *r =
 334                 (const struct reftable_ref_record *)rec;
 335         struct string_view start = s;
 336         int n = put_var_int(&s, r->update_index);
 337         assert(hash_size > 0);
 338         if (n < 0)
 339                 return -1;
 340         string_view_consume(&s, n);
 341
 342         switch (r->value_type) {
 343         case REFTABLE_REF_SYMREF:
 344                 n = encode_string(r->value.symref, s);
 345                 if (n < 0) {
 346                         return -1;
 347                 }
 348                 string_view_consume(&s, n);
 349                 break;
 350         case REFTABLE_REF_VAL2:
 351                 if (s.len < 2 * hash_size) {
 352                         return -1;
 353                 }
 354                 memcpy(s.buf, r->value.val2.value, hash_size);
 355                 string_view_consume(&s, hash_size);
 356                 memcpy(s.buf, r->value.val2.target_value, hash_size);
 357                 string_view_consume(&s, hash_size);
 358                 break;
 359         case REFTABLE_REF_VAL1:
 360                 if (s.len < hash_size) {
 361                         return -1;
 362                 }
 363                 memcpy(s.buf, r->value.val1, hash_size);
 364                 string_view_consume(&s, hash_size);
 365                 break;
 366         case REFTABLE_REF_DELETION:
 367                 break;
 368         default:
 369                 abort();
 370         }
 371
 372         return start.len - s.len;
 373 }
 374
 375 static int reftable_ref_record_decode(void *rec, struct strbuf key,
 376                                       uint8_t val_type, struct string_view in,
 377                                       int hash_size, struct strbuf *scratch)
 378 {
 379         struct reftable_ref_record *r = rec;
 380         struct string_view start = in;
 381         uint64_t update_index = 0;
 382         const char *refname = NULL;
 383         size_t refname_cap = 0;
 384         int n;
 385
 386         assert(hash_size > 0);
 387
 388         n = get_var_int(&update_index, &in);
 389         if (n < 0)
 390                 return n;
 391         string_view_consume(&in, n);
 392
 393         SWAP(refname, r->refname);
 394         SWAP(refname_cap, r->refname_cap);
 395         reftable_ref_record_release(r);
 396         SWAP(r->refname, refname);
 397         SWAP(r->refname_cap, refname_cap);
 398
 399         REFTABLE_ALLOC_GROW(r->refname, key.len + 1, r->refname_cap);
 400         memcpy(r->refname, key.buf, key.len);
 401         r->refname[key.len] = 0;
 402
 403         r->update_index = update_index;
 404         r->value_type = val_type;
 405         switch (val_type) {
 406         case REFTABLE_REF_VAL1:
 407                 if (in.len < hash_size) {
 408                         return -1;
 409                 }
 410
 411                 memcpy(r->value.val1, in.buf, hash_size);
 412                 string_view_consume(&in, hash_size);
 413                 break;
 414
 415         case REFTABLE_REF_VAL2:
 416                 if (in.len < 2 * hash_size) {
 417                         return -1;
 418                 }
 419
 420                 memcpy(r->value.val2.value, in.buf, hash_size);
 421                 string_view_consume(&in, hash_size);
 422
 423                 memcpy(r->value.val2.target_value, in.buf, hash_size);
 424                 string_view_consume(&in, hash_size);
 425                 break;
 426
 427         case REFTABLE_REF_SYMREF: {
 428                 int n = decode_string(scratch, in);
 429                 if (n < 0) {
 430                         return -1;
 431                 }
 432                 string_view_consume(&in, n);
 433                 r->value.symref = strbuf_detach(scratch, NULL);
 434         } break;
 435
 436         case REFTABLE_REF_DELETION:
 437                 break;
 438         default:
 439                 abort();
 440                 break;
 441         }
 442
 443         return start.len - in.len;
 444 }
 445
 446 static int reftable_ref_record_is_deletion_void(const void *p)
 447 {
 448         return reftable_ref_record_is_deletion(
 449                 (const struct reftable_ref_record *)p);
 450 }
 451
 452 static int reftable_ref_record_equal_void(const void *a,
 453                                           const void *b, int hash_size)
 454 {
 455         struct reftable_ref_record *ra = (struct reftable_ref_record *) a;
 456         struct reftable_ref_record *rb = (struct reftable_ref_record *) b;
 457         return reftable_ref_record_equal(ra, rb, hash_size);
 458 }
 459
 460 static int reftable_ref_record_cmp_void(const void *_a, const void *_b)
 461 {
 462         const struct reftable_ref_record *a = _a;
 463         const struct reftable_ref_record *b = _b;
 464         return strcmp(a->refname, b->refname);
 465 }
 466
 467 static void reftable_ref_record_print_void(const void *rec,
 468                                            int hash_size)
 469 {
 470         reftable_ref_record_print_sz((struct reftable_ref_record *) rec, hash_size);
 471 }
 472
 473 static struct reftable_record_vtable reftable_ref_record_vtable = {
 474         .key = &reftable_ref_record_key,
 475         .type = BLOCK_TYPE_REF,
 476         .copy_from = &reftable_ref_record_copy_from,
 477         .val_type = &reftable_ref_record_val_type,
 478         .encode = &reftable_ref_record_encode,
 479         .decode = &reftable_ref_record_decode,
 480         .release = &reftable_ref_record_release_void,
 481         .is_deletion = &reftable_ref_record_is_deletion_void,
 482         .equal = &reftable_ref_record_equal_void,
 483         .cmp = &reftable_ref_record_cmp_void,
 484         .print = &reftable_ref_record_print_void,
 485 };
 486
 487 static void reftable_obj_record_key(const void *r, struct strbuf *dest)
 488 {
 489         const struct reftable_obj_record *rec =
 490                 (const struct reftable_obj_record *)r;
 491         strbuf_reset(dest);
 492         strbuf_add(dest, rec->hash_prefix, rec->hash_prefix_len);
 493 }
 494
 495 static void reftable_obj_record_release(void *rec)
 496 {
 497         struct reftable_obj_record *obj = rec;
 498         FREE_AND_NULL(obj->hash_prefix);
 499         FREE_AND_NULL(obj->offsets);
 500         memset(obj, 0, sizeof(struct reftable_obj_record));
 501 }
 502
 503 static void reftable_obj_record_print(const void *rec, int hash_size)
 504 {
 505         const struct reftable_obj_record *obj = rec;
 506         char hex[GIT_MAX_HEXSZ + 1] = { 0 };
 507         struct strbuf offset_str = STRBUF_INIT;
 508         int i;
 509
 510         for (i = 0; i < obj->offset_len; i++)
 511                 strbuf_addf(&offset_str, "%" PRIu64 " ", obj->offsets[i]);
 512         hex_format(hex, obj->hash_prefix, obj->hash_prefix_len);
 513         printf("prefix %s (len %d), offsets [%s]\n",
 514                hex, obj->hash_prefix_len, offset_str.buf);
 515         strbuf_release(&offset_str);
 516 }
 517
 518 static void reftable_obj_record_copy_from(void *rec, const void *src_rec,
 519                                           int hash_size)
 520 {
 521         struct reftable_obj_record *obj = rec;
 522         const struct reftable_obj_record *src =
 523                 (const struct reftable_obj_record *)src_rec;
 524
 525         reftable_obj_record_release(obj);
 526
 527         REFTABLE_ALLOC_ARRAY(obj->hash_prefix, src->hash_prefix_len);
 528         obj->hash_prefix_len = src->hash_prefix_len;
 529         if (src->hash_prefix_len)
 530                 memcpy(obj->hash_prefix, src->hash_prefix, obj->hash_prefix_len);
 531
 532         REFTABLE_ALLOC_ARRAY(obj->offsets, src->offset_len);
 533         obj->offset_len = src->offset_len;
 534         COPY_ARRAY(obj->offsets, src->offsets, src->offset_len);
 535 }
 536
 537 static uint8_t reftable_obj_record_val_type(const void *rec)
 538 {
 539         const struct reftable_obj_record *r = rec;
 540         if (r->offset_len > 0 && r->offset_len < 8)
 541                 return r->offset_len;
 542         return 0;
 543 }
 544
 545 static int reftable_obj_record_encode(const void *rec, struct string_view s,
 546                                       int hash_size)
 547 {
 548         const struct reftable_obj_record *r = rec;
 549         struct string_view start = s;
 550         int i = 0;
 551         int n = 0;
 552         uint64_t last = 0;
 553         if (r->offset_len == 0 || r->offset_len >= 8) {
 554                 n = put_var_int(&s, r->offset_len);
 555                 if (n < 0) {
 556                         return -1;
 557                 }
 558                 string_view_consume(&s, n);
 559         }
 560         if (r->offset_len == 0)
 561                 return start.len - s.len;
 562         n = put_var_int(&s, r->offsets[0]);
 563         if (n < 0)
 564                 return -1;
 565         string_view_consume(&s, n);
 566
 567         last = r->offsets[0];
 568         for (i = 1; i < r->offset_len; i++) {
 569                 int n = put_var_int(&s, r->offsets[i] - last);
 570                 if (n < 0) {
 571                         return -1;
 572                 }
 573                 string_view_consume(&s, n);
 574                 last = r->offsets[i];
 575         }
 576         return start.len - s.len;
 577 }
 578
 579 static int reftable_obj_record_decode(void *rec, struct strbuf key,
 580                                       uint8_t val_type, struct string_view in,
 581                                       int hash_size, struct strbuf *scratch UNUSED)
 582 {
 583         struct string_view start = in;
 584         struct reftable_obj_record *r = rec;
 585         uint64_t count = val_type;
 586         int n = 0;
 587         uint64_t last;
 588         int j;
 589
 590         reftable_obj_record_release(r);
 591
 592         REFTABLE_ALLOC_ARRAY(r->hash_prefix, key.len);
 593         memcpy(r->hash_prefix, key.buf, key.len);
 594         r->hash_prefix_len = key.len;
 595
 596         if (val_type == 0) {
 597                 n = get_var_int(&count, &in);
 598                 if (n < 0) {
 599                         return n;
 600                 }
 601
 602                 string_view_consume(&in, n);
 603         }
 604
 605         r->offsets = NULL;
 606         r->offset_len = 0;
 607         if (count == 0)
 608                 return start.len - in.len;
 609
 610         REFTABLE_ALLOC_ARRAY(r->offsets, count);
 611         r->offset_len = count;
 612
 613         n = get_var_int(&r->offsets[0], &in);
 614         if (n < 0)
 615                 return n;
 616         string_view_consume(&in, n);
 617
 618         last = r->offsets[0];
 619         j = 1;
 620         while (j < count) {
 621                 uint64_t delta = 0;
 622                 int n = get_var_int(&delta, &in);
 623                 if (n < 0) {
 624                         return n;
 625                 }
 626                 string_view_consume(&in, n);
 627
 628                 last = r->offsets[j] = (delta + last);
 629                 j++;
 630         }
 631         return start.len - in.len;
 632 }
 633
 634 static int not_a_deletion(const void *p)
 635 {
 636         return 0;
 637 }
 638
 639 static int reftable_obj_record_equal_void(const void *a, const void *b, int hash_size)
 640 {
 641         struct reftable_obj_record *ra = (struct reftable_obj_record *) a;
 642         struct reftable_obj_record *rb = (struct reftable_obj_record *) b;
 643
 644         if (ra->hash_prefix_len != rb->hash_prefix_len
 645             || ra->offset_len != rb->offset_len)
 646                 return 0;
 647
 648         if (ra->hash_prefix_len &&
 649             memcmp(ra->hash_prefix, rb->hash_prefix, ra->hash_prefix_len))
 650                 return 0;
 651         if (ra->offset_len &&
 652             memcmp(ra->offsets, rb->offsets, ra->offset_len * sizeof(uint64_t)))
 653                 return 0;
 654
 655         return 1;
 656 }
 657
 658 static int reftable_obj_record_cmp_void(const void *_a, const void *_b)
 659 {
 660         const struct reftable_obj_record *a = _a;
 661         const struct reftable_obj_record *b = _b;
 662         int cmp;
 663
 664         cmp = memcmp(a->hash_prefix, b->hash_prefix,
 665                      a->hash_prefix_len > b->hash_prefix_len ?
 666                      a->hash_prefix_len : b->hash_prefix_len);
 667         if (cmp)
 668                 return cmp;
 669
 670         /*
 671          * When the prefix is the same then the object record that is longer is
 672          * considered to be bigger.
 673          */
 674         return a->hash_prefix_len - b->hash_prefix_len;
 675 }
 676
 677 static struct reftable_record_vtable reftable_obj_record_vtable = {
 678         .key = &reftable_obj_record_key,
 679         .type = BLOCK_TYPE_OBJ,
 680         .copy_from = &reftable_obj_record_copy_from,
 681         .val_type = &reftable_obj_record_val_type,
 682         .encode = &reftable_obj_record_encode,
 683         .decode = &reftable_obj_record_decode,
 684         .release = &reftable_obj_record_release,
 685         .is_deletion = &not_a_deletion,
 686         .equal = &reftable_obj_record_equal_void,
 687         .cmp = &reftable_obj_record_cmp_void,
 688         .print = &reftable_obj_record_print,
 689 };
 690
 691 static void reftable_log_record_print_sz(struct reftable_log_record *log,
 692                                          int hash_size)
 693 {
 694         char hex[GIT_MAX_HEXSZ + 1] = { 0 };
 695
 696         switch (log->value_type) {
 697         case REFTABLE_LOG_DELETION:
 698                 printf("log{%s(%" PRIu64 ") delete\n", log->refname,
 699                        log->update_index);
 700                 break;
 701         case REFTABLE_LOG_UPDATE:
 702                 printf("log{%s(%" PRIu64 ") %s <%s> %" PRIu64 " %04d\n",
 703                        log->refname, log->update_index,
 704                        log->value.update.name ? log->value.update.name : "",
 705                        log->value.update.email ? log->value.update.email : "",
 706                        log->value.update.time,
 707                        log->value.update.tz_offset);
 708                 hex_format(hex, log->value.update.old_hash, hash_size);
 709                 printf("%s => ", hex);
 710                 hex_format(hex, log->value.update.new_hash, hash_size);
 711                 printf("%s\n\n%s\n}\n", hex,
 712                        log->value.update.message ? log->value.update.message : "");
 713                 break;
 714         }
 715 }
 716
 717 void reftable_log_record_print(struct reftable_log_record *log,
 718                                       uint32_t hash_id)
 719 {
 720         reftable_log_record_print_sz(log, hash_size(hash_id));
 721 }
 722
 723 static void reftable_log_record_key(const void *r, struct strbuf *dest)
 724 {
 725         const struct reftable_log_record *rec =
 726                 (const struct reftable_log_record *)r;
 727         int len = strlen(rec->refname);
 728         uint8_t i64[8];
 729         uint64_t ts = 0;
 730         strbuf_reset(dest);
 731         strbuf_add(dest, (uint8_t *)rec->refname, len + 1);
 732
 733         ts = (~ts) - rec->update_index;
 734         put_be64(&i64[0], ts);
 735         strbuf_add(dest, i64, sizeof(i64));
 736 }
 737
 738 static void reftable_log_record_copy_from(void *rec, const void *src_rec,
 739                                           int hash_size)
 740 {
 741         struct reftable_log_record *dst = rec;
 742         const struct reftable_log_record *src =
 743                 (const struct reftable_log_record *)src_rec;
 744
 745         reftable_log_record_release(dst);
 746         *dst = *src;
 747         if (dst->refname) {
 748                 dst->refname = xstrdup(dst->refname);
 749         }
 750         switch (dst->value_type) {
 751         case REFTABLE_LOG_DELETION:
 752                 break;
 753         case REFTABLE_LOG_UPDATE:
 754                 if (dst->value.update.email) {
 755                         dst->value.update.email =
 756                                 xstrdup(dst->value.update.email);
 757                 }
 758                 if (dst->value.update.name) {
 759                         dst->value.update.name =
 760                                 xstrdup(dst->value.update.name);
 761                 }
 762                 if (dst->value.update.message) {
 763                         dst->value.update.message =
 764                                 xstrdup(dst->value.update.message);
 765                 }
 766
 767                 memcpy(dst->value.update.new_hash,
 768                        src->value.update.new_hash, hash_size);
 769                 memcpy(dst->value.update.old_hash,
 770                        src->value.update.old_hash, hash_size);
 771                 break;
 772         }
 773 }
 774
 775 static void reftable_log_record_release_void(void *rec)
 776 {
 777         struct reftable_log_record *r = rec;
 778         reftable_log_record_release(r);
 779 }
 780
 781 void reftable_log_record_release(struct reftable_log_record *r)
 782 {
 783         reftable_free(r->refname);
 784         switch (r->value_type) {
 785         case REFTABLE_LOG_DELETION:
 786                 break;
 787         case REFTABLE_LOG_UPDATE:
 788                 reftable_free(r->value.update.name);
 789                 reftable_free(r->value.update.email);
 790                 reftable_free(r->value.update.message);
 791                 break;
 792         }
 793         memset(r, 0, sizeof(struct reftable_log_record));
 794 }
 795
 796 static uint8_t reftable_log_record_val_type(const void *rec)
 797 {
 798         const struct reftable_log_record *log =
 799                 (const struct reftable_log_record *)rec;
 800
 801         return reftable_log_record_is_deletion(log) ? 0 : 1;
 802 }
 803
 804 static int reftable_log_record_encode(const void *rec, struct string_view s,
 805                                       int hash_size)
 806 {
 807         const struct reftable_log_record *r = rec;
 808         struct string_view start = s;
 809         int n = 0;
 810         if (reftable_log_record_is_deletion(r))
 811                 return 0;
 812
 813         if (s.len < 2 * hash_size)
 814                 return -1;
 815
 816         memcpy(s.buf, r->value.update.old_hash, hash_size);
 817         memcpy(s.buf + hash_size, r->value.update.new_hash, hash_size);
 818         string_view_consume(&s, 2 * hash_size);
 819
 820         n = encode_string(r->value.update.name ? r->value.update.name : "", s);
 821         if (n < 0)
 822                 return -1;
 823         string_view_consume(&s, n);
 824
 825         n = encode_string(r->value.update.email ? r->value.update.email : "",
 826                           s);
 827         if (n < 0)
 828                 return -1;
 829         string_view_consume(&s, n);
 830
 831         n = put_var_int(&s, r->value.update.time);
 832         if (n < 0)
 833                 return -1;
 834         string_view_consume(&s, n);
 835
 836         if (s.len < 2)
 837                 return -1;
 838
 839         put_be16(s.buf, r->value.update.tz_offset);
 840         string_view_consume(&s, 2);
 841
 842         n = encode_string(
 843                 r->value.update.message ? r->value.update.message : "", s);
 844         if (n < 0)
 845                 return -1;
 846         string_view_consume(&s, n);
 847
 848         return start.len - s.len;
 849 }
 850
 851 static int reftable_log_record_decode(void *rec, struct strbuf key,
 852                                       uint8_t val_type, struct string_view in,
 853                                       int hash_size, struct strbuf *scratch)
 854 {
 855         struct string_view start = in;
 856         struct reftable_log_record *r = rec;
 857         uint64_t max = 0;
 858         uint64_t ts = 0;
 859         int n;
 860
 861         if (key.len <= 9 || key.buf[key.len - 9] != 0)
 862                 return REFTABLE_FORMAT_ERROR;
 863
 864         REFTABLE_ALLOC_GROW(r->refname, key.len - 8, r->refname_cap);
 865         memcpy(r->refname, key.buf, key.len - 8);
 866         ts = get_be64(key.buf + key.len - 8);
 867
 868         r->update_index = (~max) - ts;
 869
 870         if (val_type != r->value_type) {
 871                 switch (r->value_type) {
 872                 case REFTABLE_LOG_UPDATE:
 873                         FREE_AND_NULL(r->value.update.message);
 874                         r->value.update.message_cap = 0;
 875                         FREE_AND_NULL(r->value.update.email);
 876                         FREE_AND_NULL(r->value.update.name);
 877                         break;
 878                 case REFTABLE_LOG_DELETION:
 879                         break;
 880                 }
 881         }
 882
 883         r->value_type = val_type;
 884         if (val_type == REFTABLE_LOG_DELETION)
 885                 return 0;
 886
 887         if (in.len < 2 * hash_size)
 888                 return REFTABLE_FORMAT_ERROR;
 889
 890         memcpy(r->value.update.old_hash, in.buf, hash_size);
 891         memcpy(r->value.update.new_hash, in.buf + hash_size, hash_size);
 892
 893         string_view_consume(&in, 2 * hash_size);
 894
 895         n = decode_string(scratch, in);
 896         if (n < 0)
 897                 goto done;
 898         string_view_consume(&in, n);
 899
 900         /*
 901          * In almost all cases we can expect the reflog name to not change for
 902          * reflog entries as they are tied to the local identity, not to the
 903          * target commits. As an optimization for this common case we can thus
 904          * skip copying over the name in case it's accurate already.
 905          */
 906         if (!r->value.update.name ||
 907             strcmp(r->value.update.name, scratch->buf)) {
 908                 r->value.update.name =
 909                         reftable_realloc(r->value.update.name, scratch->len + 1);
 910                 memcpy(r->value.update.name, scratch->buf, scratch->len);
 911                 r->value.update.name[scratch->len] = 0;
 912         }
 913
 914         n = decode_string(scratch, in);
 915         if (n < 0)
 916                 goto done;
 917         string_view_consume(&in, n);
 918
 919         /* Same as above, but for the reflog email. */
 920         if (!r->value.update.email ||
 921             strcmp(r->value.update.email, scratch->buf)) {
 922                 r->value.update.email =
 923                         reftable_realloc(r->value.update.email, scratch->len + 1);
 924                 memcpy(r->value.update.email, scratch->buf, scratch->len);
 925                 r->value.update.email[scratch->len] = 0;
 926         }
 927
 928         ts = 0;
 929         n = get_var_int(&ts, &in);
 930         if (n < 0)
 931                 goto done;
 932         string_view_consume(&in, n);
 933         r->value.update.time = ts;
 934         if (in.len < 2)
 935                 goto done;
 936
 937         r->value.update.tz_offset = get_be16(in.buf);
 938         string_view_consume(&in, 2);
 939
 940         n = decode_string(scratch, in);
 941         if (n < 0)
 942                 goto done;
 943         string_view_consume(&in, n);
 944
 945         REFTABLE_ALLOC_GROW(r->value.update.message, scratch->len + 1,
 946                             r->value.update.message_cap);
 947         memcpy(r->value.update.message, scratch->buf, scratch->len);
 948         r->value.update.message[scratch->len] = 0;
 949
 950         return start.len - in.len;
 951
 952 done:
 953         return REFTABLE_FORMAT_ERROR;
 954 }
 955
 956 static int null_streq(char *a, char *b)
 957 {
 958         char *empty = "";
 959         if (!a)
 960                 a = empty;
 961
 962         if (!b)
 963                 b = empty;
 964
 965         return 0 == strcmp(a, b);
 966 }
 967
 968 static int reftable_log_record_equal_void(const void *a,
 969                                           const void *b, int hash_size)
 970 {
 971         return reftable_log_record_equal((struct reftable_log_record *) a,
 972                                          (struct reftable_log_record *) b,
 973                                          hash_size);
 974 }
 975
 976 static int reftable_log_record_cmp_void(const void *_a, const void *_b)
 977 {
 978         const struct reftable_log_record *a = _a;
 979         const struct reftable_log_record *b = _b;
 980         int cmp = strcmp(a->refname, b->refname);
 981         if (cmp)
 982                 return cmp;
 983
 984         /*
 985          * Note that the comparison here is reversed. This is because the
 986          * update index is reversed when comparing keys. For reference, see how
 987          * we handle this in reftable_log_record_key()`.
 988          */
 989         return b->update_index - a->update_index;
 990 }
 991
 992 int reftable_log_record_equal(const struct reftable_log_record *a,
 993                               const struct reftable_log_record *b, int hash_size)
 994 {
 995         if (!(null_streq(a->refname, b->refname) &&
 996               a->update_index == b->update_index &&
 997               a->value_type == b->value_type))
 998                 return 0;
 999
1000         switch (a->value_type) {
1001         case REFTABLE_LOG_DELETION:
1002                 return 1;
1003         case REFTABLE_LOG_UPDATE:
1004                 return null_streq(a->value.update.name, b->value.update.name) &&
1005                        a->value.update.time == b->value.update.time &&
1006                        a->value.update.tz_offset == b->value.update.tz_offset &&
1007                        null_streq(a->value.update.email,
1008                                   b->value.update.email) &&
1009                        null_streq(a->value.update.message,
1010                                   b->value.update.message) &&
1011                        !memcmp(a->value.update.old_hash,
1012                                b->value.update.old_hash, hash_size) &&
1013                        !memcmp(a->value.update.new_hash,
1014                                b->value.update.new_hash, hash_size);
1015         }
1016
1017         abort();
1018 }
1019
1020 static int reftable_log_record_is_deletion_void(const void *p)
1021 {
1022         return reftable_log_record_is_deletion(
1023                 (const struct reftable_log_record *)p);
1024 }
1025
1026 static void reftable_log_record_print_void(const void *rec, int hash_size)
1027 {
1028         reftable_log_record_print_sz((struct reftable_log_record*)rec, hash_size);
1029 }
1030
1031 static struct reftable_record_vtable reftable_log_record_vtable = {
1032         .key = &reftable_log_record_key,
1033         .type = BLOCK_TYPE_LOG,
1034         .copy_from = &reftable_log_record_copy_from,
1035         .val_type = &reftable_log_record_val_type,
1036         .encode = &reftable_log_record_encode,
1037         .decode = &reftable_log_record_decode,
1038         .release = &reftable_log_record_release_void,
1039         .is_deletion = &reftable_log_record_is_deletion_void,
1040         .equal = &reftable_log_record_equal_void,
1041         .cmp = &reftable_log_record_cmp_void,
1042         .print = &reftable_log_record_print_void,
1043 };
1044
1045 static void reftable_index_record_key(const void *r, struct strbuf *dest)
1046 {
1047         const struct reftable_index_record *rec = r;
1048         strbuf_reset(dest);
1049         strbuf_addbuf(dest, &rec->last_key);
1050 }
1051
1052 static void reftable_index_record_copy_from(void *rec, const void *src_rec,
1053                                             int hash_size)
1054 {
1055         struct reftable_index_record *dst = rec;
1056         const struct reftable_index_record *src = src_rec;
1057
1058         strbuf_reset(&dst->last_key);
1059         strbuf_addbuf(&dst->last_key, &src->last_key);
1060         dst->offset = src->offset;
1061 }
1062
1063 static void reftable_index_record_release(void *rec)
1064 {
1065         struct reftable_index_record *idx = rec;
1066         strbuf_release(&idx->last_key);
1067 }
1068
1069 static uint8_t reftable_index_record_val_type(const void *rec)
1070 {
1071         return 0;
1072 }
1073
1074 static int reftable_index_record_encode(const void *rec, struct string_view out,
1075                                         int hash_size)
1076 {
1077         const struct reftable_index_record *r =
1078                 (const struct reftable_index_record *)rec;
1079         struct string_view start = out;
1080
1081         int n = put_var_int(&out, r->offset);
1082         if (n < 0)
1083                 return n;
1084
1085         string_view_consume(&out, n);
1086
1087         return start.len - out.len;
1088 }
1089
1090 static int reftable_index_record_decode(void *rec, struct strbuf key,
1091                                         uint8_t val_type, struct string_view in,
1092                                         int hash_size, struct strbuf *scratch UNUSED)
1093 {
1094         struct string_view start = in;
1095         struct reftable_index_record *r = rec;
1096         int n = 0;
1097
1098         strbuf_reset(&r->last_key);
1099         strbuf_addbuf(&r->last_key, &key);
1100
1101         n = get_var_int(&r->offset, &in);
1102         if (n < 0)
1103                 return n;
1104
1105         string_view_consume(&in, n);
1106         return start.len - in.len;
1107 }
1108
1109 static int reftable_index_record_equal(const void *a, const void *b, int hash_size)
1110 {
1111         struct reftable_index_record *ia = (struct reftable_index_record *) a;
1112         struct reftable_index_record *ib = (struct reftable_index_record *) b;
1113
1114         return ia->offset == ib->offset && !strbuf_cmp(&ia->last_key, &ib->last_key);
1115 }
1116
1117 static int reftable_index_record_cmp(const void *_a, const void *_b)
1118 {
1119         const struct reftable_index_record *a = _a;
1120         const struct reftable_index_record *b = _b;
1121         return strbuf_cmp(&a->last_key, &b->last_key);
1122 }
1123
1124 static void reftable_index_record_print(const void *rec, int hash_size)
1125 {
1126         const struct reftable_index_record *idx = rec;
1127         /* TODO: escape null chars? */
1128         printf("\"%s\" %" PRIu64 "\n", idx->last_key.buf, idx->offset);
1129 }
1130
1131 static struct reftable_record_vtable reftable_index_record_vtable = {
1132         .key = &reftable_index_record_key,
1133         .type = BLOCK_TYPE_INDEX,
1134         .copy_from = &reftable_index_record_copy_from,
1135         .val_type = &reftable_index_record_val_type,
1136         .encode = &reftable_index_record_encode,
1137         .decode = &reftable_index_record_decode,
1138         .release = &reftable_index_record_release,
1139         .is_deletion = &not_a_deletion,
1140         .equal = &reftable_index_record_equal,
1141         .cmp = &reftable_index_record_cmp,
1142         .print = &reftable_index_record_print,
1143 };
1144
1145 void reftable_record_key(struct reftable_record *rec, struct strbuf *dest)
1146 {
1147         reftable_record_vtable(rec)->key(reftable_record_data(rec), dest);
1148 }
1149
1150 int reftable_record_encode(struct reftable_record *rec, struct string_view dest,
1151                            int hash_size)
1152 {
1153         return reftable_record_vtable(rec)->encode(reftable_record_data(rec),
1154                                                    dest, hash_size);
1155 }
1156
1157 void reftable_record_copy_from(struct reftable_record *rec,
1158                                struct reftable_record *src, int hash_size)
1159 {
1160         assert(src->type == rec->type);
1161
1162         reftable_record_vtable(rec)->copy_from(reftable_record_data(rec),
1163                                                reftable_record_data(src),
1164                                                hash_size);
1165 }
1166
1167 uint8_t reftable_record_val_type(struct reftable_record *rec)
1168 {
1169         return reftable_record_vtable(rec)->val_type(reftable_record_data(rec));
1170 }
1171
1172 int reftable_record_decode(struct reftable_record *rec, struct strbuf key,
1173                            uint8_t extra, struct string_view src, int hash_size,
1174                            struct strbuf *scratch)
1175 {
1176         return reftable_record_vtable(rec)->decode(reftable_record_data(rec),
1177                                                    key, extra, src, hash_size,
1178                                                    scratch);
1179 }
1180
1181 void reftable_record_release(struct reftable_record *rec)
1182 {
1183         reftable_record_vtable(rec)->release(reftable_record_data(rec));
1184 }
1185
1186 int reftable_record_is_deletion(struct reftable_record *rec)
1187 {
1188         return reftable_record_vtable(rec)->is_deletion(
1189                 reftable_record_data(rec));
1190 }
1191
1192 int reftable_record_cmp(struct reftable_record *a, struct reftable_record *b)
1193 {
1194         if (a->type != b->type)
1195                 BUG("cannot compare reftable records of different type");
1196         return reftable_record_vtable(a)->cmp(
1197                 reftable_record_data(a), reftable_record_data(b));
1198 }
1199
1200 int reftable_record_equal(struct reftable_record *a, struct reftable_record *b, int hash_size)
1201 {
1202         if (a->type != b->type)
1203                 return 0;
1204         return reftable_record_vtable(a)->equal(
1205                 reftable_record_data(a), reftable_record_data(b), hash_size);
1206 }
1207
1208 static int hash_equal(const unsigned char *a, const unsigned char *b, int hash_size)
1209 {
1210         if (a && b)
1211                 return !memcmp(a, b, hash_size);
1212
1213         return a == b;
1214 }
1215
1216 int reftable_ref_record_equal(const struct reftable_ref_record *a,
1217                               const struct reftable_ref_record *b, int hash_size)
1218 {
1219         assert(hash_size > 0);
1220         if (!null_streq(a->refname, b->refname))
1221                 return 0;
1222
1223         if (a->update_index != b->update_index ||
1224             a->value_type != b->value_type)
1225                 return 0;
1226
1227         switch (a->value_type) {
1228         case REFTABLE_REF_SYMREF:
1229                 return !strcmp(a->value.symref, b->value.symref);
1230         case REFTABLE_REF_VAL2:
1231                 return hash_equal(a->value.val2.value, b->value.val2.value,
1232                                   hash_size) &&
1233                        hash_equal(a->value.val2.target_value,
1234                                   b->value.val2.target_value, hash_size);
1235         case REFTABLE_REF_VAL1:
1236                 return hash_equal(a->value.val1, b->value.val1, hash_size);
1237         case REFTABLE_REF_DELETION:
1238                 return 1;
1239         default:
1240                 abort();
1241         }
1242 }
1243
1244 int reftable_ref_record_compare_name(const void *a, const void *b)
1245 {
1246         return strcmp(((struct reftable_ref_record *)a)->refname,
1247                       ((struct reftable_ref_record *)b)->refname);
1248 }
1249
1250 int reftable_ref_record_is_deletion(const struct reftable_ref_record *ref)
1251 {
1252         return ref->value_type == REFTABLE_REF_DELETION;
1253 }
1254
1255 int reftable_log_record_compare_key(const void *a, const void *b)
1256 {
1257         const struct reftable_log_record *la = a;
1258         const struct reftable_log_record *lb = b;
1259
1260         int cmp = strcmp(la->refname, lb->refname);
1261         if (cmp)
1262                 return cmp;
1263         if (la->update_index > lb->update_index)
1264                 return -1;
1265         return (la->update_index < lb->update_index) ? 1 : 0;
1266 }
1267
1268 int reftable_log_record_is_deletion(const struct reftable_log_record *log)
1269 {
1270         return (log->value_type == REFTABLE_LOG_DELETION);
1271 }
1272
1273 static void *reftable_record_data(struct reftable_record *rec)
1274 {
1275         switch (rec->type) {
1276         case BLOCK_TYPE_REF:
1277                 return &rec->u.ref;
1278         case BLOCK_TYPE_LOG:
1279                 return &rec->u.log;
1280         case BLOCK_TYPE_INDEX:
1281                 return &rec->u.idx;
1282         case BLOCK_TYPE_OBJ:
1283                 return &rec->u.obj;
1284         }
1285         abort();
1286 }
1287
1288 static struct reftable_record_vtable *
1289 reftable_record_vtable(struct reftable_record *rec)
1290 {
1291         switch (rec->type) {
1292         case BLOCK_TYPE_REF:
1293                 return &reftable_ref_record_vtable;
1294         case BLOCK_TYPE_LOG:
1295                 return &reftable_log_record_vtable;
1296         case BLOCK_TYPE_INDEX:
1297                 return &reftable_index_record_vtable;
1298         case BLOCK_TYPE_OBJ:
1299                 return &reftable_obj_record_vtable;
1300         }
1301         abort();
1302 }
1303
1304 void reftable_record_init(struct reftable_record *rec, uint8_t typ)
1305 {
1306         memset(rec, 0, sizeof(*rec));
1307         rec->type = typ;
1308
1309         switch (typ) {
1310         case BLOCK_TYPE_REF:
1311         case BLOCK_TYPE_LOG:
1312         case BLOCK_TYPE_OBJ:
1313                 return;
1314         case BLOCK_TYPE_INDEX:
1315                 strbuf_init(&rec->u.idx.last_key, 0);
1316                 return;
1317         default:
1318                 BUG("unhandled record type");
1319         }
1320 }
1321
1322 void reftable_record_print(struct reftable_record *rec, int hash_size)
1323 {
1324         printf("'%c': ", rec->type);
1325         reftable_record_vtable(rec)->print(reftable_record_data(rec), hash_size);
1326 }