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_ALLOC_ARRAY(r->hash_prefix, key.len);
 591         memcpy(r->hash_prefix, key.buf, key.len);
 592         r->hash_prefix_len = key.len;
 593
 594         if (val_type == 0) {
 595                 n = get_var_int(&count, &in);
 596                 if (n < 0) {
 597                         return n;
 598                 }
 599
 600                 string_view_consume(&in, n);
 601         }
 602
 603         r->offsets = NULL;
 604         r->offset_len = 0;
 605         if (count == 0)
 606                 return start.len - in.len;
 607
 608         REFTABLE_ALLOC_ARRAY(r->offsets, count);
 609         r->offset_len = count;
 610
 611         n = get_var_int(&r->offsets[0], &in);
 612         if (n < 0)
 613                 return n;
 614         string_view_consume(&in, n);
 615
 616         last = r->offsets[0];
 617         j = 1;
 618         while (j < count) {
 619                 uint64_t delta = 0;
 620                 int n = get_var_int(&delta, &in);
 621                 if (n < 0) {
 622                         return n;
 623                 }
 624                 string_view_consume(&in, n);
 625
 626                 last = r->offsets[j] = (delta + last);
 627                 j++;
 628         }
 629         return start.len - in.len;
 630 }
 631
 632 static int not_a_deletion(const void *p)
 633 {
 634         return 0;
 635 }
 636
 637 static int reftable_obj_record_equal_void(const void *a, const void *b, int hash_size)
 638 {
 639         struct reftable_obj_record *ra = (struct reftable_obj_record *) a;
 640         struct reftable_obj_record *rb = (struct reftable_obj_record *) b;
 641
 642         if (ra->hash_prefix_len != rb->hash_prefix_len
 643             || ra->offset_len != rb->offset_len)
 644                 return 0;
 645
 646         if (ra->hash_prefix_len &&
 647             memcmp(ra->hash_prefix, rb->hash_prefix, ra->hash_prefix_len))
 648                 return 0;
 649         if (ra->offset_len &&
 650             memcmp(ra->offsets, rb->offsets, ra->offset_len * sizeof(uint64_t)))
 651                 return 0;
 652
 653         return 1;
 654 }
 655
 656 static int reftable_obj_record_cmp_void(const void *_a, const void *_b)
 657 {
 658         const struct reftable_obj_record *a = _a;
 659         const struct reftable_obj_record *b = _b;
 660         int cmp;
 661
 662         cmp = memcmp(a->hash_prefix, b->hash_prefix,
 663                      a->hash_prefix_len > b->hash_prefix_len ?
 664                      a->hash_prefix_len : b->hash_prefix_len);
 665         if (cmp)
 666                 return cmp;
 667
 668         /*
 669          * When the prefix is the same then the object record that is longer is
 670          * considered to be bigger.
 671          */
 672         return a->hash_prefix_len - b->hash_prefix_len;
 673 }
 674
 675 static struct reftable_record_vtable reftable_obj_record_vtable = {
 676         .key = &reftable_obj_record_key,
 677         .type = BLOCK_TYPE_OBJ,
 678         .copy_from = &reftable_obj_record_copy_from,
 679         .val_type = &reftable_obj_record_val_type,
 680         .encode = &reftable_obj_record_encode,
 681         .decode = &reftable_obj_record_decode,
 682         .release = &reftable_obj_record_release,
 683         .is_deletion = &not_a_deletion,
 684         .equal = &reftable_obj_record_equal_void,
 685         .cmp = &reftable_obj_record_cmp_void,
 686         .print = &reftable_obj_record_print,
 687 };
 688
 689 static void reftable_log_record_print_sz(struct reftable_log_record *log,
 690                                          int hash_size)
 691 {
 692         char hex[GIT_MAX_HEXSZ + 1] = { 0 };
 693
 694         switch (log->value_type) {
 695         case REFTABLE_LOG_DELETION:
 696                 printf("log{%s(%" PRIu64 ") delete\n", log->refname,
 697                        log->update_index);
 698                 break;
 699         case REFTABLE_LOG_UPDATE:
 700                 printf("log{%s(%" PRIu64 ") %s <%s> %" PRIu64 " %04d\n",
 701                        log->refname, log->update_index,
 702                        log->value.update.name ? log->value.update.name : "",
 703                        log->value.update.email ? log->value.update.email : "",
 704                        log->value.update.time,
 705                        log->value.update.tz_offset);
 706                 hex_format(hex, log->value.update.old_hash, hash_size);
 707                 printf("%s => ", hex);
 708                 hex_format(hex, log->value.update.new_hash, hash_size);
 709                 printf("%s\n\n%s\n}\n", hex,
 710                        log->value.update.message ? log->value.update.message : "");
 711                 break;
 712         }
 713 }
 714
 715 void reftable_log_record_print(struct reftable_log_record *log,
 716                                       uint32_t hash_id)
 717 {
 718         reftable_log_record_print_sz(log, hash_size(hash_id));
 719 }
 720
 721 static void reftable_log_record_key(const void *r, struct strbuf *dest)
 722 {
 723         const struct reftable_log_record *rec =
 724                 (const struct reftable_log_record *)r;
 725         int len = strlen(rec->refname);
 726         uint8_t i64[8];
 727         uint64_t ts = 0;
 728         strbuf_reset(dest);
 729         strbuf_add(dest, (uint8_t *)rec->refname, len + 1);
 730
 731         ts = (~ts) - rec->update_index;
 732         put_be64(&i64[0], ts);
 733         strbuf_add(dest, i64, sizeof(i64));
 734 }
 735
 736 static void reftable_log_record_copy_from(void *rec, const void *src_rec,
 737                                           int hash_size)
 738 {
 739         struct reftable_log_record *dst = rec;
 740         const struct reftable_log_record *src =
 741                 (const struct reftable_log_record *)src_rec;
 742
 743         reftable_log_record_release(dst);
 744         *dst = *src;
 745         if (dst->refname) {
 746                 dst->refname = xstrdup(dst->refname);
 747         }
 748         switch (dst->value_type) {
 749         case REFTABLE_LOG_DELETION:
 750                 break;
 751         case REFTABLE_LOG_UPDATE:
 752                 if (dst->value.update.email) {
 753                         dst->value.update.email =
 754                                 xstrdup(dst->value.update.email);
 755                 }
 756                 if (dst->value.update.name) {
 757                         dst->value.update.name =
 758                                 xstrdup(dst->value.update.name);
 759                 }
 760                 if (dst->value.update.message) {
 761                         dst->value.update.message =
 762                                 xstrdup(dst->value.update.message);
 763                 }
 764
 765                 memcpy(dst->value.update.new_hash,
 766                        src->value.update.new_hash, hash_size);
 767                 memcpy(dst->value.update.old_hash,
 768                        src->value.update.old_hash, hash_size);
 769                 break;
 770         }
 771 }
 772
 773 static void reftable_log_record_release_void(void *rec)
 774 {
 775         struct reftable_log_record *r = rec;
 776         reftable_log_record_release(r);
 777 }
 778
 779 void reftable_log_record_release(struct reftable_log_record *r)
 780 {
 781         reftable_free(r->refname);
 782         switch (r->value_type) {
 783         case REFTABLE_LOG_DELETION:
 784                 break;
 785         case REFTABLE_LOG_UPDATE:
 786                 reftable_free(r->value.update.name);
 787                 reftable_free(r->value.update.email);
 788                 reftable_free(r->value.update.message);
 789                 break;
 790         }
 791         memset(r, 0, sizeof(struct reftable_log_record));
 792 }
 793
 794 static uint8_t reftable_log_record_val_type(const void *rec)
 795 {
 796         const struct reftable_log_record *log =
 797                 (const struct reftable_log_record *)rec;
 798
 799         return reftable_log_record_is_deletion(log) ? 0 : 1;
 800 }
 801
 802 static int reftable_log_record_encode(const void *rec, struct string_view s,
 803                                       int hash_size)
 804 {
 805         const struct reftable_log_record *r = rec;
 806         struct string_view start = s;
 807         int n = 0;
 808         if (reftable_log_record_is_deletion(r))
 809                 return 0;
 810
 811         if (s.len < 2 * hash_size)
 812                 return -1;
 813
 814         memcpy(s.buf, r->value.update.old_hash, hash_size);
 815         memcpy(s.buf + hash_size, r->value.update.new_hash, hash_size);
 816         string_view_consume(&s, 2 * hash_size);
 817
 818         n = encode_string(r->value.update.name ? r->value.update.name : "", s);
 819         if (n < 0)
 820                 return -1;
 821         string_view_consume(&s, n);
 822
 823         n = encode_string(r->value.update.email ? r->value.update.email : "",
 824                           s);
 825         if (n < 0)
 826                 return -1;
 827         string_view_consume(&s, n);
 828
 829         n = put_var_int(&s, r->value.update.time);
 830         if (n < 0)
 831                 return -1;
 832         string_view_consume(&s, n);
 833
 834         if (s.len < 2)
 835                 return -1;
 836
 837         put_be16(s.buf, r->value.update.tz_offset);
 838         string_view_consume(&s, 2);
 839
 840         n = encode_string(
 841                 r->value.update.message ? r->value.update.message : "", s);
 842         if (n < 0)
 843                 return -1;
 844         string_view_consume(&s, n);
 845
 846         return start.len - s.len;
 847 }
 848
 849 static int reftable_log_record_decode(void *rec, struct strbuf key,
 850                                       uint8_t val_type, struct string_view in,
 851                                       int hash_size, struct strbuf *scratch)
 852 {
 853         struct string_view start = in;
 854         struct reftable_log_record *r = rec;
 855         uint64_t max = 0;
 856         uint64_t ts = 0;
 857         int n;
 858
 859         if (key.len <= 9 || key.buf[key.len - 9] != 0)
 860                 return REFTABLE_FORMAT_ERROR;
 861
 862         REFTABLE_ALLOC_GROW(r->refname, key.len - 8, r->refname_cap);
 863         memcpy(r->refname, key.buf, key.len - 8);
 864         ts = get_be64(key.buf + key.len - 8);
 865
 866         r->update_index = (~max) - ts;
 867
 868         if (val_type != r->value_type) {
 869                 switch (r->value_type) {
 870                 case REFTABLE_LOG_UPDATE:
 871                         FREE_AND_NULL(r->value.update.message);
 872                         r->value.update.message_cap = 0;
 873                         FREE_AND_NULL(r->value.update.email);
 874                         FREE_AND_NULL(r->value.update.name);
 875                         break;
 876                 case REFTABLE_LOG_DELETION:
 877                         break;
 878                 }
 879         }
 880
 881         r->value_type = val_type;
 882         if (val_type == REFTABLE_LOG_DELETION)
 883                 return 0;
 884
 885         if (in.len < 2 * hash_size)
 886                 return REFTABLE_FORMAT_ERROR;
 887
 888         memcpy(r->value.update.old_hash, in.buf, hash_size);
 889         memcpy(r->value.update.new_hash, in.buf + hash_size, hash_size);
 890
 891         string_view_consume(&in, 2 * hash_size);
 892
 893         n = decode_string(scratch, in);
 894         if (n < 0)
 895                 goto done;
 896         string_view_consume(&in, n);
 897
 898         /*
 899          * In almost all cases we can expect the reflog name to not change for
 900          * reflog entries as they are tied to the local identity, not to the
 901          * target commits. As an optimization for this common case we can thus
 902          * skip copying over the name in case it's accurate already.
 903          */
 904         if (!r->value.update.name ||
 905             strcmp(r->value.update.name, scratch->buf)) {
 906                 r->value.update.name =
 907                         reftable_realloc(r->value.update.name, scratch->len + 1);
 908                 memcpy(r->value.update.name, scratch->buf, scratch->len);
 909                 r->value.update.name[scratch->len] = 0;
 910         }
 911
 912         n = decode_string(scratch, in);
 913         if (n < 0)
 914                 goto done;
 915         string_view_consume(&in, n);
 916
 917         /* Same as above, but for the reflog email. */
 918         if (!r->value.update.email ||
 919             strcmp(r->value.update.email, scratch->buf)) {
 920                 r->value.update.email =
 921                         reftable_realloc(r->value.update.email, scratch->len + 1);
 922                 memcpy(r->value.update.email, scratch->buf, scratch->len);
 923                 r->value.update.email[scratch->len] = 0;
 924         }
 925
 926         ts = 0;
 927         n = get_var_int(&ts, &in);
 928         if (n < 0)
 929                 goto done;
 930         string_view_consume(&in, n);
 931         r->value.update.time = ts;
 932         if (in.len < 2)
 933                 goto done;
 934
 935         r->value.update.tz_offset = get_be16(in.buf);
 936         string_view_consume(&in, 2);
 937
 938         n = decode_string(scratch, in);
 939         if (n < 0)
 940                 goto done;
 941         string_view_consume(&in, n);
 942
 943         REFTABLE_ALLOC_GROW(r->value.update.message, scratch->len + 1,
 944                             r->value.update.message_cap);
 945         memcpy(r->value.update.message, scratch->buf, scratch->len);
 946         r->value.update.message[scratch->len] = 0;
 947
 948         return start.len - in.len;
 949
 950 done:
 951         return REFTABLE_FORMAT_ERROR;
 952 }
 953
 954 static int null_streq(char *a, char *b)
 955 {
 956         char *empty = "";
 957         if (!a)
 958                 a = empty;
 959
 960         if (!b)
 961                 b = empty;
 962
 963         return 0 == strcmp(a, b);
 964 }
 965
 966 static int reftable_log_record_equal_void(const void *a,
 967                                           const void *b, int hash_size)
 968 {
 969         return reftable_log_record_equal((struct reftable_log_record *) a,
 970                                          (struct reftable_log_record *) b,
 971                                          hash_size);
 972 }
 973
 974 static int reftable_log_record_cmp_void(const void *_a, const void *_b)
 975 {
 976         const struct reftable_log_record *a = _a;
 977         const struct reftable_log_record *b = _b;
 978         int cmp = strcmp(a->refname, b->refname);
 979         if (cmp)
 980                 return cmp;
 981
 982         /*
 983          * Note that the comparison here is reversed. This is because the
 984          * update index is reversed when comparing keys. For reference, see how
 985          * we handle this in reftable_log_record_key()`.
 986          */
 987         return b->update_index - a->update_index;
 988 }
 989
 990 int reftable_log_record_equal(const struct reftable_log_record *a,
 991                               const struct reftable_log_record *b, int hash_size)
 992 {
 993         if (!(null_streq(a->refname, b->refname) &&
 994               a->update_index == b->update_index &&
 995               a->value_type == b->value_type))
 996                 return 0;
 997
 998         switch (a->value_type) {
 999         case REFTABLE_LOG_DELETION:
1000                 return 1;
1001         case REFTABLE_LOG_UPDATE:
1002                 return null_streq(a->value.update.name, b->value.update.name) &&
1003                        a->value.update.time == b->value.update.time &&
1004                        a->value.update.tz_offset == b->value.update.tz_offset &&
1005                        null_streq(a->value.update.email,
1006                                   b->value.update.email) &&
1007                        null_streq(a->value.update.message,
1008                                   b->value.update.message) &&
1009                        !memcmp(a->value.update.old_hash,
1010                                b->value.update.old_hash, hash_size) &&
1011                        !memcmp(a->value.update.new_hash,
1012                                b->value.update.new_hash, hash_size);
1013         }
1014
1015         abort();
1016 }
1017
1018 static int reftable_log_record_is_deletion_void(const void *p)
1019 {
1020         return reftable_log_record_is_deletion(
1021                 (const struct reftable_log_record *)p);
1022 }
1023
1024 static void reftable_log_record_print_void(const void *rec, int hash_size)
1025 {
1026         reftable_log_record_print_sz((struct reftable_log_record*)rec, hash_size);
1027 }
1028
1029 static struct reftable_record_vtable reftable_log_record_vtable = {
1030         .key = &reftable_log_record_key,
1031         .type = BLOCK_TYPE_LOG,
1032         .copy_from = &reftable_log_record_copy_from,
1033         .val_type = &reftable_log_record_val_type,
1034         .encode = &reftable_log_record_encode,
1035         .decode = &reftable_log_record_decode,
1036         .release = &reftable_log_record_release_void,
1037         .is_deletion = &reftable_log_record_is_deletion_void,
1038         .equal = &reftable_log_record_equal_void,
1039         .cmp = &reftable_log_record_cmp_void,
1040         .print = &reftable_log_record_print_void,
1041 };
1042
1043 static void reftable_index_record_key(const void *r, struct strbuf *dest)
1044 {
1045         const struct reftable_index_record *rec = r;
1046         strbuf_reset(dest);
1047         strbuf_addbuf(dest, &rec->last_key);
1048 }
1049
1050 static void reftable_index_record_copy_from(void *rec, const void *src_rec,
1051                                             int hash_size)
1052 {
1053         struct reftable_index_record *dst = rec;
1054         const struct reftable_index_record *src = src_rec;
1055
1056         strbuf_reset(&dst->last_key);
1057         strbuf_addbuf(&dst->last_key, &src->last_key);
1058         dst->offset = src->offset;
1059 }
1060
1061 static void reftable_index_record_release(void *rec)
1062 {
1063         struct reftable_index_record *idx = rec;
1064         strbuf_release(&idx->last_key);
1065 }
1066
1067 static uint8_t reftable_index_record_val_type(const void *rec)
1068 {
1069         return 0;
1070 }
1071
1072 static int reftable_index_record_encode(const void *rec, struct string_view out,
1073                                         int hash_size)
1074 {
1075         const struct reftable_index_record *r =
1076                 (const struct reftable_index_record *)rec;
1077         struct string_view start = out;
1078
1079         int n = put_var_int(&out, r->offset);
1080         if (n < 0)
1081                 return n;
1082
1083         string_view_consume(&out, n);
1084
1085         return start.len - out.len;
1086 }
1087
1088 static int reftable_index_record_decode(void *rec, struct strbuf key,
1089                                         uint8_t val_type, struct string_view in,
1090                                         int hash_size, struct strbuf *scratch UNUSED)
1091 {
1092         struct string_view start = in;
1093         struct reftable_index_record *r = rec;
1094         int n = 0;
1095
1096         strbuf_reset(&r->last_key);
1097         strbuf_addbuf(&r->last_key, &key);
1098
1099         n = get_var_int(&r->offset, &in);
1100         if (n < 0)
1101                 return n;
1102
1103         string_view_consume(&in, n);
1104         return start.len - in.len;
1105 }
1106
1107 static int reftable_index_record_equal(const void *a, const void *b, int hash_size)
1108 {
1109         struct reftable_index_record *ia = (struct reftable_index_record *) a;
1110         struct reftable_index_record *ib = (struct reftable_index_record *) b;
1111
1112         return ia->offset == ib->offset && !strbuf_cmp(&ia->last_key, &ib->last_key);
1113 }
1114
1115 static int reftable_index_record_cmp(const void *_a, const void *_b)
1116 {
1117         const struct reftable_index_record *a = _a;
1118         const struct reftable_index_record *b = _b;
1119         return strbuf_cmp(&a->last_key, &b->last_key);
1120 }
1121
1122 static void reftable_index_record_print(const void *rec, int hash_size)
1123 {
1124         const struct reftable_index_record *idx = rec;
1125         /* TODO: escape null chars? */
1126         printf("\"%s\" %" PRIu64 "\n", idx->last_key.buf, idx->offset);
1127 }
1128
1129 static struct reftable_record_vtable reftable_index_record_vtable = {
1130         .key = &reftable_index_record_key,
1131         .type = BLOCK_TYPE_INDEX,
1132         .copy_from = &reftable_index_record_copy_from,
1133         .val_type = &reftable_index_record_val_type,
1134         .encode = &reftable_index_record_encode,
1135         .decode = &reftable_index_record_decode,
1136         .release = &reftable_index_record_release,
1137         .is_deletion = &not_a_deletion,
1138         .equal = &reftable_index_record_equal,
1139         .cmp = &reftable_index_record_cmp,
1140         .print = &reftable_index_record_print,
1141 };
1142
1143 void reftable_record_key(struct reftable_record *rec, struct strbuf *dest)
1144 {
1145         reftable_record_vtable(rec)->key(reftable_record_data(rec), dest);
1146 }
1147
1148 int reftable_record_encode(struct reftable_record *rec, struct string_view dest,
1149                            int hash_size)
1150 {
1151         return reftable_record_vtable(rec)->encode(reftable_record_data(rec),
1152                                                    dest, hash_size);
1153 }
1154
1155 void reftable_record_copy_from(struct reftable_record *rec,
1156                                struct reftable_record *src, int hash_size)
1157 {
1158         assert(src->type == rec->type);
1159
1160         reftable_record_vtable(rec)->copy_from(reftable_record_data(rec),
1161                                                reftable_record_data(src),
1162                                                hash_size);
1163 }
1164
1165 uint8_t reftable_record_val_type(struct reftable_record *rec)
1166 {
1167         return reftable_record_vtable(rec)->val_type(reftable_record_data(rec));
1168 }
1169
1170 int reftable_record_decode(struct reftable_record *rec, struct strbuf key,
1171                            uint8_t extra, struct string_view src, int hash_size,
1172                            struct strbuf *scratch)
1173 {
1174         return reftable_record_vtable(rec)->decode(reftable_record_data(rec),
1175                                                    key, extra, src, hash_size,
1176                                                    scratch);
1177 }
1178
1179 void reftable_record_release(struct reftable_record *rec)
1180 {
1181         reftable_record_vtable(rec)->release(reftable_record_data(rec));
1182 }
1183
1184 int reftable_record_is_deletion(struct reftable_record *rec)
1185 {
1186         return reftable_record_vtable(rec)->is_deletion(
1187                 reftable_record_data(rec));
1188 }
1189
1190 int reftable_record_cmp(struct reftable_record *a, struct reftable_record *b)
1191 {
1192         if (a->type != b->type)
1193                 BUG("cannot compare reftable records of different type");
1194         return reftable_record_vtable(a)->cmp(
1195                 reftable_record_data(a), reftable_record_data(b));
1196 }
1197
1198 int reftable_record_equal(struct reftable_record *a, struct reftable_record *b, int hash_size)
1199 {
1200         if (a->type != b->type)
1201                 return 0;
1202         return reftable_record_vtable(a)->equal(
1203                 reftable_record_data(a), reftable_record_data(b), hash_size);
1204 }
1205
1206 static int hash_equal(const unsigned char *a, const unsigned char *b, int hash_size)
1207 {
1208         if (a && b)
1209                 return !memcmp(a, b, hash_size);
1210
1211         return a == b;
1212 }
1213
1214 int reftable_ref_record_equal(const struct reftable_ref_record *a,
1215                               const struct reftable_ref_record *b, int hash_size)
1216 {
1217         assert(hash_size > 0);
1218         if (!null_streq(a->refname, b->refname))
1219                 return 0;
1220
1221         if (a->update_index != b->update_index ||
1222             a->value_type != b->value_type)
1223                 return 0;
1224
1225         switch (a->value_type) {
1226         case REFTABLE_REF_SYMREF:
1227                 return !strcmp(a->value.symref, b->value.symref);
1228         case REFTABLE_REF_VAL2:
1229                 return hash_equal(a->value.val2.value, b->value.val2.value,
1230                                   hash_size) &&
1231                        hash_equal(a->value.val2.target_value,
1232                                   b->value.val2.target_value, hash_size);
1233         case REFTABLE_REF_VAL1:
1234                 return hash_equal(a->value.val1, b->value.val1, hash_size);
1235         case REFTABLE_REF_DELETION:
1236                 return 1;
1237         default:
1238                 abort();
1239         }
1240 }
1241
1242 int reftable_ref_record_compare_name(const void *a, const void *b)
1243 {
1244         return strcmp(((struct reftable_ref_record *)a)->refname,
1245                       ((struct reftable_ref_record *)b)->refname);
1246 }
1247
1248 int reftable_ref_record_is_deletion(const struct reftable_ref_record *ref)
1249 {
1250         return ref->value_type == REFTABLE_REF_DELETION;
1251 }
1252
1253 int reftable_log_record_compare_key(const void *a, const void *b)
1254 {
1255         const struct reftable_log_record *la = a;
1256         const struct reftable_log_record *lb = b;
1257
1258         int cmp = strcmp(la->refname, lb->refname);
1259         if (cmp)
1260                 return cmp;
1261         if (la->update_index > lb->update_index)
1262                 return -1;
1263         return (la->update_index < lb->update_index) ? 1 : 0;
1264 }
1265
1266 int reftable_log_record_is_deletion(const struct reftable_log_record *log)
1267 {
1268         return (log->value_type == REFTABLE_LOG_DELETION);
1269 }
1270
1271 static void *reftable_record_data(struct reftable_record *rec)
1272 {
1273         switch (rec->type) {
1274         case BLOCK_TYPE_REF:
1275                 return &rec->u.ref;
1276         case BLOCK_TYPE_LOG:
1277                 return &rec->u.log;
1278         case BLOCK_TYPE_INDEX:
1279                 return &rec->u.idx;
1280         case BLOCK_TYPE_OBJ:
1281                 return &rec->u.obj;
1282         }
1283         abort();
1284 }
1285
1286 static struct reftable_record_vtable *
1287 reftable_record_vtable(struct reftable_record *rec)
1288 {
1289         switch (rec->type) {
1290         case BLOCK_TYPE_REF:
1291                 return &reftable_ref_record_vtable;
1292         case BLOCK_TYPE_LOG:
1293                 return &reftable_log_record_vtable;
1294         case BLOCK_TYPE_INDEX:
1295                 return &reftable_index_record_vtable;
1296         case BLOCK_TYPE_OBJ:
1297                 return &reftable_obj_record_vtable;
1298         }
1299         abort();
1300 }
1301
1302 void reftable_record_init(struct reftable_record *rec, uint8_t typ)
1303 {
1304         memset(rec, 0, sizeof(*rec));
1305         rec->type = typ;
1306
1307         switch (typ) {
1308         case BLOCK_TYPE_REF:
1309         case BLOCK_TYPE_LOG:
1310         case BLOCK_TYPE_OBJ:
1311                 return;
1312         case BLOCK_TYPE_INDEX:
1313                 strbuf_init(&rec->u.idx.last_key, 0);
1314                 return;
1315         default:
1316                 BUG("unhandled record type");
1317         }
1318 }
1319
1320 void reftable_record_print(struct reftable_record *rec, int hash_size)
1321 {
1322         printf("'%c': ", rec->type);
1323         reftable_record_vtable(rec)->print(reftable_record_data(rec), hash_size);
1324 }