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 *key, uint8_t *extra,
 163                         struct strbuf last_key, 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 = get_var_int(&prefix_len, &in);
 169         if (n < 0)
 170                 return -1;
 171         string_view_consume(&in, n);
 172
 173         if (prefix_len > last_key.len)
 174                 return -1;
 175
 176         n = get_var_int(&suffix_len, &in);
 177         if (n <= 0)
 178                 return -1;
 179         string_view_consume(&in, n);
 180
 181         *extra = (uint8_t)(suffix_len & 0x7);
 182         suffix_len >>= 3;
 183
 184         if (in.len < suffix_len)
 185                 return -1;
 186
 187         strbuf_reset(key);
 188         strbuf_add(key, last_key.buf, prefix_len);
 189         strbuf_add(key, in.buf, suffix_len);
 190         string_view_consume(&in, suffix_len);
 191
 192         return start_len - in.len;
 193 }
 194
 195 static void reftable_ref_record_key(const void *r, struct strbuf *dest)
 196 {
 197         const struct reftable_ref_record *rec =
 198                 (const struct reftable_ref_record *)r;
 199         strbuf_reset(dest);
 200         strbuf_addstr(dest, rec->refname);
 201 }
 202
 203 static void reftable_ref_record_copy_from(void *rec, const void *src_rec,
 204                                           int hash_size)
 205 {
 206         struct reftable_ref_record *ref = rec;
 207         const struct reftable_ref_record *src = src_rec;
 208         assert(hash_size > 0);
 209
 210         /* This is simple and correct, but we could probably reuse the hash
 211          * fields. */
 212         reftable_ref_record_release(ref);
 213         if (src->refname) {
 214                 ref->refname = xstrdup(src->refname);
 215         }
 216         ref->update_index = src->update_index;
 217         ref->value_type = src->value_type;
 218         switch (src->value_type) {
 219         case REFTABLE_REF_DELETION:
 220                 break;
 221         case REFTABLE_REF_VAL1:
 222                 memcpy(ref->value.val1, src->value.val1, hash_size);
 223                 break;
 224         case REFTABLE_REF_VAL2:
 225                 memcpy(ref->value.val2.value, src->value.val2.value, hash_size);
 226                 memcpy(ref->value.val2.target_value,
 227                        src->value.val2.target_value, hash_size);
 228                 break;
 229         case REFTABLE_REF_SYMREF:
 230                 ref->value.symref = xstrdup(src->value.symref);
 231                 break;
 232         }
 233 }
 234
 235 static char hexdigit(int c)
 236 {
 237         if (c <= 9)
 238                 return '0' + c;
 239         return 'a' + (c - 10);
 240 }
 241
 242 static void hex_format(char *dest, const unsigned char *src, int hash_size)
 243 {
 244         assert(hash_size > 0);
 245         if (src) {
 246                 int i = 0;
 247                 for (i = 0; i < hash_size; i++) {
 248                         dest[2 * i] = hexdigit(src[i] >> 4);
 249                         dest[2 * i + 1] = hexdigit(src[i] & 0xf);
 250                 }
 251                 dest[2 * hash_size] = 0;
 252         }
 253 }
 254
 255 static void reftable_ref_record_print_sz(const struct reftable_ref_record *ref,
 256                                          int hash_size)
 257 {
 258         char hex[GIT_MAX_HEXSZ + 1] = { 0 }; /* BUG */
 259         printf("ref{%s(%" PRIu64 ") ", ref->refname, ref->update_index);
 260         switch (ref->value_type) {
 261         case REFTABLE_REF_SYMREF:
 262                 printf("=> %s", ref->value.symref);
 263                 break;
 264         case REFTABLE_REF_VAL2:
 265                 hex_format(hex, ref->value.val2.value, hash_size);
 266                 printf("val 2 %s", hex);
 267                 hex_format(hex, ref->value.val2.target_value,
 268                            hash_size);
 269                 printf("(T %s)", hex);
 270                 break;
 271         case REFTABLE_REF_VAL1:
 272                 hex_format(hex, ref->value.val1, hash_size);
 273                 printf("val 1 %s", hex);
 274                 break;
 275         case REFTABLE_REF_DELETION:
 276                 printf("delete");
 277                 break;
 278         }
 279         printf("}\n");
 280 }
 281
 282 void reftable_ref_record_print(const struct reftable_ref_record *ref,
 283                                uint32_t hash_id) {
 284         reftable_ref_record_print_sz(ref, hash_size(hash_id));
 285 }
 286
 287 static void reftable_ref_record_release_void(void *rec)
 288 {
 289         reftable_ref_record_release(rec);
 290 }
 291
 292 void reftable_ref_record_release(struct reftable_ref_record *ref)
 293 {
 294         switch (ref->value_type) {
 295         case REFTABLE_REF_SYMREF:
 296                 reftable_free(ref->value.symref);
 297                 break;
 298         case REFTABLE_REF_VAL2:
 299                 break;
 300         case REFTABLE_REF_VAL1:
 301                 break;
 302         case REFTABLE_REF_DELETION:
 303                 break;
 304         default:
 305                 abort();
 306         }
 307
 308         reftable_free(ref->refname);
 309         memset(ref, 0, sizeof(struct reftable_ref_record));
 310 }
 311
 312 static uint8_t reftable_ref_record_val_type(const void *rec)
 313 {
 314         const struct reftable_ref_record *r =
 315                 (const struct reftable_ref_record *)rec;
 316         return r->value_type;
 317 }
 318
 319 static int reftable_ref_record_encode(const void *rec, struct string_view s,
 320                                       int hash_size)
 321 {
 322         const struct reftable_ref_record *r =
 323                 (const struct reftable_ref_record *)rec;
 324         struct string_view start = s;
 325         int n = put_var_int(&s, r->update_index);
 326         assert(hash_size > 0);
 327         if (n < 0)
 328                 return -1;
 329         string_view_consume(&s, n);
 330
 331         switch (r->value_type) {
 332         case REFTABLE_REF_SYMREF:
 333                 n = encode_string(r->value.symref, s);
 334                 if (n < 0) {
 335                         return -1;
 336                 }
 337                 string_view_consume(&s, n);
 338                 break;
 339         case REFTABLE_REF_VAL2:
 340                 if (s.len < 2 * hash_size) {
 341                         return -1;
 342                 }
 343                 memcpy(s.buf, r->value.val2.value, hash_size);
 344                 string_view_consume(&s, hash_size);
 345                 memcpy(s.buf, r->value.val2.target_value, hash_size);
 346                 string_view_consume(&s, hash_size);
 347                 break;
 348         case REFTABLE_REF_VAL1:
 349                 if (s.len < hash_size) {
 350                         return -1;
 351                 }
 352                 memcpy(s.buf, r->value.val1, hash_size);
 353                 string_view_consume(&s, hash_size);
 354                 break;
 355         case REFTABLE_REF_DELETION:
 356                 break;
 357         default:
 358                 abort();
 359         }
 360
 361         return start.len - s.len;
 362 }
 363
 364 static int reftable_ref_record_decode(void *rec, struct strbuf key,
 365                                       uint8_t val_type, struct string_view in,
 366                                       int hash_size)
 367 {
 368         struct reftable_ref_record *r = rec;
 369         struct string_view start = in;
 370         uint64_t update_index = 0;
 371         int n = get_var_int(&update_index, &in);
 372         if (n < 0)
 373                 return n;
 374         string_view_consume(&in, n);
 375
 376         reftable_ref_record_release(r);
 377
 378         assert(hash_size > 0);
 379
 380         r->refname = reftable_malloc(key.len + 1);
 381         memcpy(r->refname, key.buf, key.len);
 382         r->refname[key.len] = 0;
 383
 384         r->update_index = update_index;
 385         r->value_type = val_type;
 386         switch (val_type) {
 387         case REFTABLE_REF_VAL1:
 388                 if (in.len < hash_size) {
 389                         return -1;
 390                 }
 391
 392                 memcpy(r->value.val1, in.buf, hash_size);
 393                 string_view_consume(&in, hash_size);
 394                 break;
 395
 396         case REFTABLE_REF_VAL2:
 397                 if (in.len < 2 * hash_size) {
 398                         return -1;
 399                 }
 400
 401                 memcpy(r->value.val2.value, in.buf, hash_size);
 402                 string_view_consume(&in, hash_size);
 403
 404                 memcpy(r->value.val2.target_value, in.buf, hash_size);
 405                 string_view_consume(&in, hash_size);
 406                 break;
 407
 408         case REFTABLE_REF_SYMREF: {
 409                 struct strbuf dest = STRBUF_INIT;
 410                 int n = decode_string(&dest, in);
 411                 if (n < 0) {
 412                         return -1;
 413                 }
 414                 string_view_consume(&in, n);
 415                 r->value.symref = dest.buf;
 416         } break;
 417
 418         case REFTABLE_REF_DELETION:
 419                 break;
 420         default:
 421                 abort();
 422                 break;
 423         }
 424
 425         return start.len - in.len;
 426 }
 427
 428 static int reftable_ref_record_is_deletion_void(const void *p)
 429 {
 430         return reftable_ref_record_is_deletion(
 431                 (const struct reftable_ref_record *)p);
 432 }
 433
 434 static int reftable_ref_record_equal_void(const void *a,
 435                                           const void *b, int hash_size)
 436 {
 437         struct reftable_ref_record *ra = (struct reftable_ref_record *) a;
 438         struct reftable_ref_record *rb = (struct reftable_ref_record *) b;
 439         return reftable_ref_record_equal(ra, rb, hash_size);
 440 }
 441
 442 static int reftable_ref_record_cmp_void(const void *_a, const void *_b)
 443 {
 444         const struct reftable_ref_record *a = _a;
 445         const struct reftable_ref_record *b = _b;
 446         return strcmp(a->refname, b->refname);
 447 }
 448
 449 static void reftable_ref_record_print_void(const void *rec,
 450                                            int hash_size)
 451 {
 452         reftable_ref_record_print_sz((struct reftable_ref_record *) rec, hash_size);
 453 }
 454
 455 static struct reftable_record_vtable reftable_ref_record_vtable = {
 456         .key = &reftable_ref_record_key,
 457         .type = BLOCK_TYPE_REF,
 458         .copy_from = &reftable_ref_record_copy_from,
 459         .val_type = &reftable_ref_record_val_type,
 460         .encode = &reftable_ref_record_encode,
 461         .decode = &reftable_ref_record_decode,
 462         .release = &reftable_ref_record_release_void,
 463         .is_deletion = &reftable_ref_record_is_deletion_void,
 464         .equal = &reftable_ref_record_equal_void,
 465         .cmp = &reftable_ref_record_cmp_void,
 466         .print = &reftable_ref_record_print_void,
 467 };
 468
 469 static void reftable_obj_record_key(const void *r, struct strbuf *dest)
 470 {
 471         const struct reftable_obj_record *rec =
 472                 (const struct reftable_obj_record *)r;
 473         strbuf_reset(dest);
 474         strbuf_add(dest, rec->hash_prefix, rec->hash_prefix_len);
 475 }
 476
 477 static void reftable_obj_record_release(void *rec)
 478 {
 479         struct reftable_obj_record *obj = rec;
 480         FREE_AND_NULL(obj->hash_prefix);
 481         FREE_AND_NULL(obj->offsets);
 482         memset(obj, 0, sizeof(struct reftable_obj_record));
 483 }
 484
 485 static void reftable_obj_record_print(const void *rec, int hash_size)
 486 {
 487         const struct reftable_obj_record *obj = rec;
 488         char hex[GIT_MAX_HEXSZ + 1] = { 0 };
 489         struct strbuf offset_str = STRBUF_INIT;
 490         int i;
 491
 492         for (i = 0; i < obj->offset_len; i++)
 493                 strbuf_addf(&offset_str, "%" PRIu64 " ", obj->offsets[i]);
 494         hex_format(hex, obj->hash_prefix, obj->hash_prefix_len);
 495         printf("prefix %s (len %d), offsets [%s]\n",
 496                hex, obj->hash_prefix_len, offset_str.buf);
 497         strbuf_release(&offset_str);
 498 }
 499
 500 static void reftable_obj_record_copy_from(void *rec, const void *src_rec,
 501                                           int hash_size)
 502 {
 503         struct reftable_obj_record *obj = rec;
 504         const struct reftable_obj_record *src =
 505                 (const struct reftable_obj_record *)src_rec;
 506
 507         reftable_obj_record_release(obj);
 508
 509         REFTABLE_ALLOC_ARRAY(obj->hash_prefix, src->hash_prefix_len);
 510         obj->hash_prefix_len = src->hash_prefix_len;
 511         if (src->hash_prefix_len)
 512                 memcpy(obj->hash_prefix, src->hash_prefix, obj->hash_prefix_len);
 513
 514         REFTABLE_ALLOC_ARRAY(obj->offsets, src->offset_len);
 515         obj->offset_len = src->offset_len;
 516         COPY_ARRAY(obj->offsets, src->offsets, src->offset_len);
 517 }
 518
 519 static uint8_t reftable_obj_record_val_type(const void *rec)
 520 {
 521         const struct reftable_obj_record *r = rec;
 522         if (r->offset_len > 0 && r->offset_len < 8)
 523                 return r->offset_len;
 524         return 0;
 525 }
 526
 527 static int reftable_obj_record_encode(const void *rec, struct string_view s,
 528                                       int hash_size)
 529 {
 530         const struct reftable_obj_record *r = rec;
 531         struct string_view start = s;
 532         int i = 0;
 533         int n = 0;
 534         uint64_t last = 0;
 535         if (r->offset_len == 0 || r->offset_len >= 8) {
 536                 n = put_var_int(&s, r->offset_len);
 537                 if (n < 0) {
 538                         return -1;
 539                 }
 540                 string_view_consume(&s, n);
 541         }
 542         if (r->offset_len == 0)
 543                 return start.len - s.len;
 544         n = put_var_int(&s, r->offsets[0]);
 545         if (n < 0)
 546                 return -1;
 547         string_view_consume(&s, n);
 548
 549         last = r->offsets[0];
 550         for (i = 1; i < r->offset_len; i++) {
 551                 int n = put_var_int(&s, r->offsets[i] - last);
 552                 if (n < 0) {
 553                         return -1;
 554                 }
 555                 string_view_consume(&s, n);
 556                 last = r->offsets[i];
 557         }
 558         return start.len - s.len;
 559 }
 560
 561 static int reftable_obj_record_decode(void *rec, struct strbuf key,
 562                                       uint8_t val_type, struct string_view in,
 563                                       int hash_size)
 564 {
 565         struct string_view start = in;
 566         struct reftable_obj_record *r = rec;
 567         uint64_t count = val_type;
 568         int n = 0;
 569         uint64_t last;
 570         int j;
 571
 572         REFTABLE_ALLOC_ARRAY(r->hash_prefix, key.len);
 573         memcpy(r->hash_prefix, key.buf, key.len);
 574         r->hash_prefix_len = key.len;
 575
 576         if (val_type == 0) {
 577                 n = get_var_int(&count, &in);
 578                 if (n < 0) {
 579                         return n;
 580                 }
 581
 582                 string_view_consume(&in, n);
 583         }
 584
 585         r->offsets = NULL;
 586         r->offset_len = 0;
 587         if (count == 0)
 588                 return start.len - in.len;
 589
 590         REFTABLE_ALLOC_ARRAY(r->offsets, count);
 591         r->offset_len = count;
 592
 593         n = get_var_int(&r->offsets[0], &in);
 594         if (n < 0)
 595                 return n;
 596         string_view_consume(&in, n);
 597
 598         last = r->offsets[0];
 599         j = 1;
 600         while (j < count) {
 601                 uint64_t delta = 0;
 602                 int n = get_var_int(&delta, &in);
 603                 if (n < 0) {
 604                         return n;
 605                 }
 606                 string_view_consume(&in, n);
 607
 608                 last = r->offsets[j] = (delta + last);
 609                 j++;
 610         }
 611         return start.len - in.len;
 612 }
 613
 614 static int not_a_deletion(const void *p)
 615 {
 616         return 0;
 617 }
 618
 619 static int reftable_obj_record_equal_void(const void *a, const void *b, int hash_size)
 620 {
 621         struct reftable_obj_record *ra = (struct reftable_obj_record *) a;
 622         struct reftable_obj_record *rb = (struct reftable_obj_record *) b;
 623
 624         if (ra->hash_prefix_len != rb->hash_prefix_len
 625             || ra->offset_len != rb->offset_len)
 626                 return 0;
 627
 628         if (ra->hash_prefix_len &&
 629             memcmp(ra->hash_prefix, rb->hash_prefix, ra->hash_prefix_len))
 630                 return 0;
 631         if (ra->offset_len &&
 632             memcmp(ra->offsets, rb->offsets, ra->offset_len * sizeof(uint64_t)))
 633                 return 0;
 634
 635         return 1;
 636 }
 637
 638 static int reftable_obj_record_cmp_void(const void *_a, const void *_b)
 639 {
 640         const struct reftable_obj_record *a = _a;
 641         const struct reftable_obj_record *b = _b;
 642         int cmp;
 643
 644         cmp = memcmp(a->hash_prefix, b->hash_prefix,
 645                      a->hash_prefix_len > b->hash_prefix_len ?
 646                      a->hash_prefix_len : b->hash_prefix_len);
 647         if (cmp)
 648                 return cmp;
 649
 650         /*
 651          * When the prefix is the same then the object record that is longer is
 652          * considered to be bigger.
 653          */
 654         return a->hash_prefix_len - b->hash_prefix_len;
 655 }
 656
 657 static struct reftable_record_vtable reftable_obj_record_vtable = {
 658         .key = &reftable_obj_record_key,
 659         .type = BLOCK_TYPE_OBJ,
 660         .copy_from = &reftable_obj_record_copy_from,
 661         .val_type = &reftable_obj_record_val_type,
 662         .encode = &reftable_obj_record_encode,
 663         .decode = &reftable_obj_record_decode,
 664         .release = &reftable_obj_record_release,
 665         .is_deletion = &not_a_deletion,
 666         .equal = &reftable_obj_record_equal_void,
 667         .cmp = &reftable_obj_record_cmp_void,
 668         .print = &reftable_obj_record_print,
 669 };
 670
 671 static void reftable_log_record_print_sz(struct reftable_log_record *log,
 672                                          int hash_size)
 673 {
 674         char hex[GIT_MAX_HEXSZ + 1] = { 0 };
 675
 676         switch (log->value_type) {
 677         case REFTABLE_LOG_DELETION:
 678                 printf("log{%s(%" PRIu64 ") delete\n", log->refname,
 679                        log->update_index);
 680                 break;
 681         case REFTABLE_LOG_UPDATE:
 682                 printf("log{%s(%" PRIu64 ") %s <%s> %" PRIu64 " %04d\n",
 683                        log->refname, log->update_index,
 684                        log->value.update.name ? log->value.update.name : "",
 685                        log->value.update.email ? log->value.update.email : "",
 686                        log->value.update.time,
 687                        log->value.update.tz_offset);
 688                 hex_format(hex, log->value.update.old_hash, hash_size);
 689                 printf("%s => ", hex);
 690                 hex_format(hex, log->value.update.new_hash, hash_size);
 691                 printf("%s\n\n%s\n}\n", hex,
 692                        log->value.update.message ? log->value.update.message : "");
 693                 break;
 694         }
 695 }
 696
 697 void reftable_log_record_print(struct reftable_log_record *log,
 698                                       uint32_t hash_id)
 699 {
 700         reftable_log_record_print_sz(log, hash_size(hash_id));
 701 }
 702
 703 static void reftable_log_record_key(const void *r, struct strbuf *dest)
 704 {
 705         const struct reftable_log_record *rec =
 706                 (const struct reftable_log_record *)r;
 707         int len = strlen(rec->refname);
 708         uint8_t i64[8];
 709         uint64_t ts = 0;
 710         strbuf_reset(dest);
 711         strbuf_add(dest, (uint8_t *)rec->refname, len + 1);
 712
 713         ts = (~ts) - rec->update_index;
 714         put_be64(&i64[0], ts);
 715         strbuf_add(dest, i64, sizeof(i64));
 716 }
 717
 718 static void reftable_log_record_copy_from(void *rec, const void *src_rec,
 719                                           int hash_size)
 720 {
 721         struct reftable_log_record *dst = rec;
 722         const struct reftable_log_record *src =
 723                 (const struct reftable_log_record *)src_rec;
 724
 725         reftable_log_record_release(dst);
 726         *dst = *src;
 727         if (dst->refname) {
 728                 dst->refname = xstrdup(dst->refname);
 729         }
 730         switch (dst->value_type) {
 731         case REFTABLE_LOG_DELETION:
 732                 break;
 733         case REFTABLE_LOG_UPDATE:
 734                 if (dst->value.update.email) {
 735                         dst->value.update.email =
 736                                 xstrdup(dst->value.update.email);
 737                 }
 738                 if (dst->value.update.name) {
 739                         dst->value.update.name =
 740                                 xstrdup(dst->value.update.name);
 741                 }
 742                 if (dst->value.update.message) {
 743                         dst->value.update.message =
 744                                 xstrdup(dst->value.update.message);
 745                 }
 746
 747                 if (dst->value.update.new_hash) {
 748                         REFTABLE_ALLOC_ARRAY(dst->value.update.new_hash, hash_size);
 749                         memcpy(dst->value.update.new_hash,
 750                                src->value.update.new_hash, hash_size);
 751                 }
 752                 if (dst->value.update.old_hash) {
 753                         REFTABLE_ALLOC_ARRAY(dst->value.update.old_hash, hash_size);
 754                         memcpy(dst->value.update.old_hash,
 755                                src->value.update.old_hash, hash_size);
 756                 }
 757                 break;
 758         }
 759 }
 760
 761 static void reftable_log_record_release_void(void *rec)
 762 {
 763         struct reftable_log_record *r = rec;
 764         reftable_log_record_release(r);
 765 }
 766
 767 void reftable_log_record_release(struct reftable_log_record *r)
 768 {
 769         reftable_free(r->refname);
 770         switch (r->value_type) {
 771         case REFTABLE_LOG_DELETION:
 772                 break;
 773         case REFTABLE_LOG_UPDATE:
 774                 reftable_free(r->value.update.new_hash);
 775                 reftable_free(r->value.update.old_hash);
 776                 reftable_free(r->value.update.name);
 777                 reftable_free(r->value.update.email);
 778                 reftable_free(r->value.update.message);
 779                 break;
 780         }
 781         memset(r, 0, sizeof(struct reftable_log_record));
 782 }
 783
 784 static uint8_t reftable_log_record_val_type(const void *rec)
 785 {
 786         const struct reftable_log_record *log =
 787                 (const struct reftable_log_record *)rec;
 788
 789         return reftable_log_record_is_deletion(log) ? 0 : 1;
 790 }
 791
 792 static uint8_t zero[GIT_SHA256_RAWSZ] = { 0 };
 793
 794 static int reftable_log_record_encode(const void *rec, struct string_view s,
 795                                       int hash_size)
 796 {
 797         const struct reftable_log_record *r = rec;
 798         struct string_view start = s;
 799         int n = 0;
 800         uint8_t *oldh = NULL;
 801         uint8_t *newh = NULL;
 802         if (reftable_log_record_is_deletion(r))
 803                 return 0;
 804
 805         oldh = r->value.update.old_hash;
 806         newh = r->value.update.new_hash;
 807         if (!oldh) {
 808                 oldh = zero;
 809         }
 810         if (!newh) {
 811                 newh = zero;
 812         }
 813
 814         if (s.len < 2 * hash_size)
 815                 return -1;
 816
 817         memcpy(s.buf, oldh, hash_size);
 818         memcpy(s.buf + hash_size, newh, hash_size);
 819         string_view_consume(&s, 2 * hash_size);
 820
 821         n = encode_string(r->value.update.name ? r->value.update.name : "", s);
 822         if (n < 0)
 823                 return -1;
 824         string_view_consume(&s, n);
 825
 826         n = encode_string(r->value.update.email ? r->value.update.email : "",
 827                           s);
 828         if (n < 0)
 829                 return -1;
 830         string_view_consume(&s, n);
 831
 832         n = put_var_int(&s, r->value.update.time);
 833         if (n < 0)
 834                 return -1;
 835         string_view_consume(&s, n);
 836
 837         if (s.len < 2)
 838                 return -1;
 839
 840         put_be16(s.buf, r->value.update.tz_offset);
 841         string_view_consume(&s, 2);
 842
 843         n = encode_string(
 844                 r->value.update.message ? r->value.update.message : "", s);
 845         if (n < 0)
 846                 return -1;
 847         string_view_consume(&s, n);
 848
 849         return start.len - s.len;
 850 }
 851
 852 static int reftable_log_record_decode(void *rec, struct strbuf key,
 853                                       uint8_t val_type, struct string_view in,
 854                                       int hash_size)
 855 {
 856         struct string_view start = in;
 857         struct reftable_log_record *r = rec;
 858         uint64_t max = 0;
 859         uint64_t ts = 0;
 860         struct strbuf dest = STRBUF_INIT;
 861         int n;
 862
 863         if (key.len <= 9 || key.buf[key.len - 9] != 0)
 864                 return REFTABLE_FORMAT_ERROR;
 865
 866         r->refname = reftable_realloc(r->refname, key.len - 8);
 867         memcpy(r->refname, key.buf, key.len - 8);
 868         ts = get_be64(key.buf + key.len - 8);
 869
 870         r->update_index = (~max) - ts;
 871
 872         if (val_type != r->value_type) {
 873                 switch (r->value_type) {
 874                 case REFTABLE_LOG_UPDATE:
 875                         FREE_AND_NULL(r->value.update.old_hash);
 876                         FREE_AND_NULL(r->value.update.new_hash);
 877                         FREE_AND_NULL(r->value.update.message);
 878                         FREE_AND_NULL(r->value.update.email);
 879                         FREE_AND_NULL(r->value.update.name);
 880                         break;
 881                 case REFTABLE_LOG_DELETION:
 882                         break;
 883                 }
 884         }
 885
 886         r->value_type = val_type;
 887         if (val_type == REFTABLE_LOG_DELETION)
 888                 return 0;
 889
 890         if (in.len < 2 * hash_size)
 891                 return REFTABLE_FORMAT_ERROR;
 892
 893         r->value.update.old_hash =
 894                 reftable_realloc(r->value.update.old_hash, hash_size);
 895         r->value.update.new_hash =
 896                 reftable_realloc(r->value.update.new_hash, hash_size);
 897
 898         memcpy(r->value.update.old_hash, in.buf, hash_size);
 899         memcpy(r->value.update.new_hash, in.buf + hash_size, hash_size);
 900
 901         string_view_consume(&in, 2 * hash_size);
 902
 903         n = decode_string(&dest, in);
 904         if (n < 0)
 905                 goto done;
 906         string_view_consume(&in, n);
 907
 908         r->value.update.name =
 909                 reftable_realloc(r->value.update.name, dest.len + 1);
 910         memcpy(r->value.update.name, dest.buf, dest.len);
 911         r->value.update.name[dest.len] = 0;
 912
 913         strbuf_reset(&dest);
 914         n = decode_string(&dest, in);
 915         if (n < 0)
 916                 goto done;
 917         string_view_consume(&in, n);
 918
 919         r->value.update.email =
 920                 reftable_realloc(r->value.update.email, dest.len + 1);
 921         memcpy(r->value.update.email, dest.buf, dest.len);
 922         r->value.update.email[dest.len] = 0;
 923
 924         ts = 0;
 925         n = get_var_int(&ts, &in);
 926         if (n < 0)
 927                 goto done;
 928         string_view_consume(&in, n);
 929         r->value.update.time = ts;
 930         if (in.len < 2)
 931                 goto done;
 932
 933         r->value.update.tz_offset = get_be16(in.buf);
 934         string_view_consume(&in, 2);
 935
 936         strbuf_reset(&dest);
 937         n = decode_string(&dest, in);
 938         if (n < 0)
 939                 goto done;
 940         string_view_consume(&in, n);
 941
 942         r->value.update.message =
 943                 reftable_realloc(r->value.update.message, dest.len + 1);
 944         memcpy(r->value.update.message, dest.buf, dest.len);
 945         r->value.update.message[dest.len] = 0;
 946
 947         strbuf_release(&dest);
 948         return start.len - in.len;
 949
 950 done:
 951         strbuf_release(&dest);
 952         return REFTABLE_FORMAT_ERROR;
 953 }
 954
 955 static int null_streq(char *a, char *b)
 956 {
 957         char *empty = "";
 958         if (!a)
 959                 a = empty;
 960
 961         if (!b)
 962                 b = empty;
 963
 964         return 0 == strcmp(a, b);
 965 }
 966
 967 static int zero_hash_eq(uint8_t *a, uint8_t *b, int sz)
 968 {
 969         if (!a)
 970                 a = zero;
 971
 972         if (!b)
 973                 b = zero;
 974
 975         return !memcmp(a, b, sz);
 976 }
 977
 978 static int reftable_log_record_equal_void(const void *a,
 979                                           const void *b, int hash_size)
 980 {
 981         return reftable_log_record_equal((struct reftable_log_record *) a,
 982                                          (struct reftable_log_record *) b,
 983                                          hash_size);
 984 }
 985
 986 static int reftable_log_record_cmp_void(const void *_a, const void *_b)
 987 {
 988         const struct reftable_log_record *a = _a;
 989         const struct reftable_log_record *b = _b;
 990         int cmp = strcmp(a->refname, b->refname);
 991         if (cmp)
 992                 return cmp;
 993
 994         /*
 995          * Note that the comparison here is reversed. This is because the
 996          * update index is reversed when comparing keys. For reference, see how
 997          * we handle this in reftable_log_record_key()`.
 998          */
 999         return b->update_index - a->update_index;
1000 }
1001
1002 int reftable_log_record_equal(const struct reftable_log_record *a,
1003                               const struct reftable_log_record *b, int hash_size)
1004 {
1005         if (!(null_streq(a->refname, b->refname) &&
1006               a->update_index == b->update_index &&
1007               a->value_type == b->value_type))
1008                 return 0;
1009
1010         switch (a->value_type) {
1011         case REFTABLE_LOG_DELETION:
1012                 return 1;
1013         case REFTABLE_LOG_UPDATE:
1014                 return null_streq(a->value.update.name, b->value.update.name) &&
1015                        a->value.update.time == b->value.update.time &&
1016                        a->value.update.tz_offset == b->value.update.tz_offset &&
1017                        null_streq(a->value.update.email,
1018                                   b->value.update.email) &&
1019                        null_streq(a->value.update.message,
1020                                   b->value.update.message) &&
1021                        zero_hash_eq(a->value.update.old_hash,
1022                                     b->value.update.old_hash, hash_size) &&
1023                        zero_hash_eq(a->value.update.new_hash,
1024                                     b->value.update.new_hash, hash_size);
1025         }
1026
1027         abort();
1028 }
1029
1030 static int reftable_log_record_is_deletion_void(const void *p)
1031 {
1032         return reftable_log_record_is_deletion(
1033                 (const struct reftable_log_record *)p);
1034 }
1035
1036 static void reftable_log_record_print_void(const void *rec, int hash_size)
1037 {
1038         reftable_log_record_print_sz((struct reftable_log_record*)rec, hash_size);
1039 }
1040
1041 static struct reftable_record_vtable reftable_log_record_vtable = {
1042         .key = &reftable_log_record_key,
1043         .type = BLOCK_TYPE_LOG,
1044         .copy_from = &reftable_log_record_copy_from,
1045         .val_type = &reftable_log_record_val_type,
1046         .encode = &reftable_log_record_encode,
1047         .decode = &reftable_log_record_decode,
1048         .release = &reftable_log_record_release_void,
1049         .is_deletion = &reftable_log_record_is_deletion_void,
1050         .equal = &reftable_log_record_equal_void,
1051         .cmp = &reftable_log_record_cmp_void,
1052         .print = &reftable_log_record_print_void,
1053 };
1054
1055 static void reftable_index_record_key(const void *r, struct strbuf *dest)
1056 {
1057         const struct reftable_index_record *rec = r;
1058         strbuf_reset(dest);
1059         strbuf_addbuf(dest, &rec->last_key);
1060 }
1061
1062 static void reftable_index_record_copy_from(void *rec, const void *src_rec,
1063                                             int hash_size)
1064 {
1065         struct reftable_index_record *dst = rec;
1066         const struct reftable_index_record *src = src_rec;
1067
1068         strbuf_reset(&dst->last_key);
1069         strbuf_addbuf(&dst->last_key, &src->last_key);
1070         dst->offset = src->offset;
1071 }
1072
1073 static void reftable_index_record_release(void *rec)
1074 {
1075         struct reftable_index_record *idx = rec;
1076         strbuf_release(&idx->last_key);
1077 }
1078
1079 static uint8_t reftable_index_record_val_type(const void *rec)
1080 {
1081         return 0;
1082 }
1083
1084 static int reftable_index_record_encode(const void *rec, struct string_view out,
1085                                         int hash_size)
1086 {
1087         const struct reftable_index_record *r =
1088                 (const struct reftable_index_record *)rec;
1089         struct string_view start = out;
1090
1091         int n = put_var_int(&out, r->offset);
1092         if (n < 0)
1093                 return n;
1094
1095         string_view_consume(&out, n);
1096
1097         return start.len - out.len;
1098 }
1099
1100 static int reftable_index_record_decode(void *rec, struct strbuf key,
1101                                         uint8_t val_type, struct string_view in,
1102                                         int hash_size)
1103 {
1104         struct string_view start = in;
1105         struct reftable_index_record *r = rec;
1106         int n = 0;
1107
1108         strbuf_reset(&r->last_key);
1109         strbuf_addbuf(&r->last_key, &key);
1110
1111         n = get_var_int(&r->offset, &in);
1112         if (n < 0)
1113                 return n;
1114
1115         string_view_consume(&in, n);
1116         return start.len - in.len;
1117 }
1118
1119 static int reftable_index_record_equal(const void *a, const void *b, int hash_size)
1120 {
1121         struct reftable_index_record *ia = (struct reftable_index_record *) a;
1122         struct reftable_index_record *ib = (struct reftable_index_record *) b;
1123
1124         return ia->offset == ib->offset && !strbuf_cmp(&ia->last_key, &ib->last_key);
1125 }
1126
1127 static int reftable_index_record_cmp(const void *_a, const void *_b)
1128 {
1129         const struct reftable_index_record *a = _a;
1130         const struct reftable_index_record *b = _b;
1131         return strbuf_cmp(&a->last_key, &b->last_key);
1132 }
1133
1134 static void reftable_index_record_print(const void *rec, int hash_size)
1135 {
1136         const struct reftable_index_record *idx = rec;
1137         /* TODO: escape null chars? */
1138         printf("\"%s\" %" PRIu64 "\n", idx->last_key.buf, idx->offset);
1139 }
1140
1141 static struct reftable_record_vtable reftable_index_record_vtable = {
1142         .key = &reftable_index_record_key,
1143         .type = BLOCK_TYPE_INDEX,
1144         .copy_from = &reftable_index_record_copy_from,
1145         .val_type = &reftable_index_record_val_type,
1146         .encode = &reftable_index_record_encode,
1147         .decode = &reftable_index_record_decode,
1148         .release = &reftable_index_record_release,
1149         .is_deletion = &not_a_deletion,
1150         .equal = &reftable_index_record_equal,
1151         .cmp = &reftable_index_record_cmp,
1152         .print = &reftable_index_record_print,
1153 };
1154
1155 void reftable_record_key(struct reftable_record *rec, struct strbuf *dest)
1156 {
1157         reftable_record_vtable(rec)->key(reftable_record_data(rec), dest);
1158 }
1159
1160 uint8_t reftable_record_type(struct reftable_record *rec)
1161 {
1162         return rec->type;
1163 }
1164
1165 int reftable_record_encode(struct reftable_record *rec, struct string_view dest,
1166                            int hash_size)
1167 {
1168         return reftable_record_vtable(rec)->encode(reftable_record_data(rec),
1169                                                    dest, hash_size);
1170 }
1171
1172 void reftable_record_copy_from(struct reftable_record *rec,
1173                                struct reftable_record *src, int hash_size)
1174 {
1175         assert(src->type == rec->type);
1176
1177         reftable_record_vtable(rec)->copy_from(reftable_record_data(rec),
1178                                                reftable_record_data(src),
1179                                                hash_size);
1180 }
1181
1182 uint8_t reftable_record_val_type(struct reftable_record *rec)
1183 {
1184         return reftable_record_vtable(rec)->val_type(reftable_record_data(rec));
1185 }
1186
1187 int reftable_record_decode(struct reftable_record *rec, struct strbuf key,
1188                            uint8_t extra, struct string_view src, int hash_size)
1189 {
1190         return reftable_record_vtable(rec)->decode(reftable_record_data(rec),
1191                                                    key, extra, src, hash_size);
1192 }
1193
1194 void reftable_record_release(struct reftable_record *rec)
1195 {
1196         reftable_record_vtable(rec)->release(reftable_record_data(rec));
1197 }
1198
1199 int reftable_record_is_deletion(struct reftable_record *rec)
1200 {
1201         return reftable_record_vtable(rec)->is_deletion(
1202                 reftable_record_data(rec));
1203 }
1204
1205 int reftable_record_cmp(struct reftable_record *a, struct reftable_record *b)
1206 {
1207         if (a->type != b->type)
1208                 BUG("cannot compare reftable records of different type");
1209         return reftable_record_vtable(a)->cmp(
1210                 reftable_record_data(a), reftable_record_data(b));
1211 }
1212
1213 int reftable_record_equal(struct reftable_record *a, struct reftable_record *b, int hash_size)
1214 {
1215         if (a->type != b->type)
1216                 return 0;
1217         return reftable_record_vtable(a)->equal(
1218                 reftable_record_data(a), reftable_record_data(b), hash_size);
1219 }
1220
1221 static int hash_equal(const unsigned char *a, const unsigned char *b, int hash_size)
1222 {
1223         if (a && b)
1224                 return !memcmp(a, b, hash_size);
1225
1226         return a == b;
1227 }
1228
1229 int reftable_ref_record_equal(const struct reftable_ref_record *a,
1230                               const struct reftable_ref_record *b, int hash_size)
1231 {
1232         assert(hash_size > 0);
1233         if (!null_streq(a->refname, b->refname))
1234                 return 0;
1235
1236         if (a->update_index != b->update_index ||
1237             a->value_type != b->value_type)
1238                 return 0;
1239
1240         switch (a->value_type) {
1241         case REFTABLE_REF_SYMREF:
1242                 return !strcmp(a->value.symref, b->value.symref);
1243         case REFTABLE_REF_VAL2:
1244                 return hash_equal(a->value.val2.value, b->value.val2.value,
1245                                   hash_size) &&
1246                        hash_equal(a->value.val2.target_value,
1247                                   b->value.val2.target_value, hash_size);
1248         case REFTABLE_REF_VAL1:
1249                 return hash_equal(a->value.val1, b->value.val1, hash_size);
1250         case REFTABLE_REF_DELETION:
1251                 return 1;
1252         default:
1253                 abort();
1254         }
1255 }
1256
1257 int reftable_ref_record_compare_name(const void *a, const void *b)
1258 {
1259         return strcmp(((struct reftable_ref_record *)a)->refname,
1260                       ((struct reftable_ref_record *)b)->refname);
1261 }
1262
1263 int reftable_ref_record_is_deletion(const struct reftable_ref_record *ref)
1264 {
1265         return ref->value_type == REFTABLE_REF_DELETION;
1266 }
1267
1268 int reftable_log_record_compare_key(const void *a, const void *b)
1269 {
1270         const struct reftable_log_record *la = a;
1271         const struct reftable_log_record *lb = b;
1272
1273         int cmp = strcmp(la->refname, lb->refname);
1274         if (cmp)
1275                 return cmp;
1276         if (la->update_index > lb->update_index)
1277                 return -1;
1278         return (la->update_index < lb->update_index) ? 1 : 0;
1279 }
1280
1281 int reftable_log_record_is_deletion(const struct reftable_log_record *log)
1282 {
1283         return (log->value_type == REFTABLE_LOG_DELETION);
1284 }
1285
1286 void string_view_consume(struct string_view *s, int n)
1287 {
1288         s->buf += n;
1289         s->len -= n;
1290 }
1291
1292 static void *reftable_record_data(struct reftable_record *rec)
1293 {
1294         switch (rec->type) {
1295         case BLOCK_TYPE_REF:
1296                 return &rec->u.ref;
1297         case BLOCK_TYPE_LOG:
1298                 return &rec->u.log;
1299         case BLOCK_TYPE_INDEX:
1300                 return &rec->u.idx;
1301         case BLOCK_TYPE_OBJ:
1302                 return &rec->u.obj;
1303         }
1304         abort();
1305 }
1306
1307 static struct reftable_record_vtable *
1308 reftable_record_vtable(struct reftable_record *rec)
1309 {
1310         switch (rec->type) {
1311         case BLOCK_TYPE_REF:
1312                 return &reftable_ref_record_vtable;
1313         case BLOCK_TYPE_LOG:
1314                 return &reftable_log_record_vtable;
1315         case BLOCK_TYPE_INDEX:
1316                 return &reftable_index_record_vtable;
1317         case BLOCK_TYPE_OBJ:
1318                 return &reftable_obj_record_vtable;
1319         }
1320         abort();
1321 }
1322
1323 void reftable_record_init(struct reftable_record *rec, uint8_t typ)
1324 {
1325         memset(rec, 0, sizeof(*rec));
1326         rec->type = typ;
1327
1328         switch (typ) {
1329         case BLOCK_TYPE_REF:
1330         case BLOCK_TYPE_LOG:
1331         case BLOCK_TYPE_OBJ:
1332                 return;
1333         case BLOCK_TYPE_INDEX:
1334                 strbuf_init(&rec->u.idx.last_key, 0);
1335                 return;
1336         default:
1337                 BUG("unhandled record type");
1338         }
1339 }
1340
1341 void reftable_record_print(struct reftable_record *rec, int hash_size)
1342 {
1343         printf("'%c': ", rec->type);
1344         reftable_record_vtable(rec)->print(reftable_record_data(rec), hash_size);
1345 }