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_obj_record_release(r);
 573
 574         REFTABLE_ALLOC_ARRAY(r->hash_prefix, key.len);
 575         memcpy(r->hash_prefix, key.buf, key.len);
 576         r->hash_prefix_len = key.len;
 577
 578         if (val_type == 0) {
 579                 n = get_var_int(&count, &in);
 580                 if (n < 0) {
 581                         return n;
 582                 }
 583
 584                 string_view_consume(&in, n);
 585         }
 586
 587         r->offsets = NULL;
 588         r->offset_len = 0;
 589         if (count == 0)
 590                 return start.len - in.len;
 591
 592         REFTABLE_ALLOC_ARRAY(r->offsets, count);
 593         r->offset_len = count;
 594
 595         n = get_var_int(&r->offsets[0], &in);
 596         if (n < 0)
 597                 return n;
 598         string_view_consume(&in, n);
 599
 600         last = r->offsets[0];
 601         j = 1;
 602         while (j < count) {
 603                 uint64_t delta = 0;
 604                 int n = get_var_int(&delta, &in);
 605                 if (n < 0) {
 606                         return n;
 607                 }
 608                 string_view_consume(&in, n);
 609
 610                 last = r->offsets[j] = (delta + last);
 611                 j++;
 612         }
 613         return start.len - in.len;
 614 }
 615
 616 static int not_a_deletion(const void *p)
 617 {
 618         return 0;
 619 }
 620
 621 static int reftable_obj_record_equal_void(const void *a, const void *b, int hash_size)
 622 {
 623         struct reftable_obj_record *ra = (struct reftable_obj_record *) a;
 624         struct reftable_obj_record *rb = (struct reftable_obj_record *) b;
 625
 626         if (ra->hash_prefix_len != rb->hash_prefix_len
 627             || ra->offset_len != rb->offset_len)
 628                 return 0;
 629
 630         if (ra->hash_prefix_len &&
 631             memcmp(ra->hash_prefix, rb->hash_prefix, ra->hash_prefix_len))
 632                 return 0;
 633         if (ra->offset_len &&
 634             memcmp(ra->offsets, rb->offsets, ra->offset_len * sizeof(uint64_t)))
 635                 return 0;
 636
 637         return 1;
 638 }
 639
 640 static int reftable_obj_record_cmp_void(const void *_a, const void *_b)
 641 {
 642         const struct reftable_obj_record *a = _a;
 643         const struct reftable_obj_record *b = _b;
 644         int cmp;
 645
 646         cmp = memcmp(a->hash_prefix, b->hash_prefix,
 647                      a->hash_prefix_len > b->hash_prefix_len ?
 648                      a->hash_prefix_len : b->hash_prefix_len);
 649         if (cmp)
 650                 return cmp;
 651
 652         /*
 653          * When the prefix is the same then the object record that is longer is
 654          * considered to be bigger.
 655          */
 656         return a->hash_prefix_len - b->hash_prefix_len;
 657 }
 658
 659 static struct reftable_record_vtable reftable_obj_record_vtable = {
 660         .key = &reftable_obj_record_key,
 661         .type = BLOCK_TYPE_OBJ,
 662         .copy_from = &reftable_obj_record_copy_from,
 663         .val_type = &reftable_obj_record_val_type,
 664         .encode = &reftable_obj_record_encode,
 665         .decode = &reftable_obj_record_decode,
 666         .release = &reftable_obj_record_release,
 667         .is_deletion = &not_a_deletion,
 668         .equal = &reftable_obj_record_equal_void,
 669         .cmp = &reftable_obj_record_cmp_void,
 670         .print = &reftable_obj_record_print,
 671 };
 672
 673 static void reftable_log_record_print_sz(struct reftable_log_record *log,
 674                                          int hash_size)
 675 {
 676         char hex[GIT_MAX_HEXSZ + 1] = { 0 };
 677
 678         switch (log->value_type) {
 679         case REFTABLE_LOG_DELETION:
 680                 printf("log{%s(%" PRIu64 ") delete\n", log->refname,
 681                        log->update_index);
 682                 break;
 683         case REFTABLE_LOG_UPDATE:
 684                 printf("log{%s(%" PRIu64 ") %s <%s> %" PRIu64 " %04d\n",
 685                        log->refname, log->update_index,
 686                        log->value.update.name ? log->value.update.name : "",
 687                        log->value.update.email ? log->value.update.email : "",
 688                        log->value.update.time,
 689                        log->value.update.tz_offset);
 690                 hex_format(hex, log->value.update.old_hash, hash_size);
 691                 printf("%s => ", hex);
 692                 hex_format(hex, log->value.update.new_hash, hash_size);
 693                 printf("%s\n\n%s\n}\n", hex,
 694                        log->value.update.message ? log->value.update.message : "");
 695                 break;
 696         }
 697 }
 698
 699 void reftable_log_record_print(struct reftable_log_record *log,
 700                                       uint32_t hash_id)
 701 {
 702         reftable_log_record_print_sz(log, hash_size(hash_id));
 703 }
 704
 705 static void reftable_log_record_key(const void *r, struct strbuf *dest)
 706 {
 707         const struct reftable_log_record *rec =
 708                 (const struct reftable_log_record *)r;
 709         int len = strlen(rec->refname);
 710         uint8_t i64[8];
 711         uint64_t ts = 0;
 712         strbuf_reset(dest);
 713         strbuf_add(dest, (uint8_t *)rec->refname, len + 1);
 714
 715         ts = (~ts) - rec->update_index;
 716         put_be64(&i64[0], ts);
 717         strbuf_add(dest, i64, sizeof(i64));
 718 }
 719
 720 static void reftable_log_record_copy_from(void *rec, const void *src_rec,
 721                                           int hash_size)
 722 {
 723         struct reftable_log_record *dst = rec;
 724         const struct reftable_log_record *src =
 725                 (const struct reftable_log_record *)src_rec;
 726
 727         reftable_log_record_release(dst);
 728         *dst = *src;
 729         if (dst->refname) {
 730                 dst->refname = xstrdup(dst->refname);
 731         }
 732         switch (dst->value_type) {
 733         case REFTABLE_LOG_DELETION:
 734                 break;
 735         case REFTABLE_LOG_UPDATE:
 736                 if (dst->value.update.email) {
 737                         dst->value.update.email =
 738                                 xstrdup(dst->value.update.email);
 739                 }
 740                 if (dst->value.update.name) {
 741                         dst->value.update.name =
 742                                 xstrdup(dst->value.update.name);
 743                 }
 744                 if (dst->value.update.message) {
 745                         dst->value.update.message =
 746                                 xstrdup(dst->value.update.message);
 747                 }
 748
 749                 if (dst->value.update.new_hash) {
 750                         REFTABLE_ALLOC_ARRAY(dst->value.update.new_hash, hash_size);
 751                         memcpy(dst->value.update.new_hash,
 752                                src->value.update.new_hash, hash_size);
 753                 }
 754                 if (dst->value.update.old_hash) {
 755                         REFTABLE_ALLOC_ARRAY(dst->value.update.old_hash, hash_size);
 756                         memcpy(dst->value.update.old_hash,
 757                                src->value.update.old_hash, hash_size);
 758                 }
 759                 break;
 760         }
 761 }
 762
 763 static void reftable_log_record_release_void(void *rec)
 764 {
 765         struct reftable_log_record *r = rec;
 766         reftable_log_record_release(r);
 767 }
 768
 769 void reftable_log_record_release(struct reftable_log_record *r)
 770 {
 771         reftable_free(r->refname);
 772         switch (r->value_type) {
 773         case REFTABLE_LOG_DELETION:
 774                 break;
 775         case REFTABLE_LOG_UPDATE:
 776                 reftable_free(r->value.update.new_hash);
 777                 reftable_free(r->value.update.old_hash);
 778                 reftable_free(r->value.update.name);
 779                 reftable_free(r->value.update.email);
 780                 reftable_free(r->value.update.message);
 781                 break;
 782         }
 783         memset(r, 0, sizeof(struct reftable_log_record));
 784 }
 785
 786 static uint8_t reftable_log_record_val_type(const void *rec)
 787 {
 788         const struct reftable_log_record *log =
 789                 (const struct reftable_log_record *)rec;
 790
 791         return reftable_log_record_is_deletion(log) ? 0 : 1;
 792 }
 793
 794 static uint8_t zero[GIT_SHA256_RAWSZ] = { 0 };
 795
 796 static int reftable_log_record_encode(const void *rec, struct string_view s,
 797                                       int hash_size)
 798 {
 799         const struct reftable_log_record *r = rec;
 800         struct string_view start = s;
 801         int n = 0;
 802         uint8_t *oldh = NULL;
 803         uint8_t *newh = NULL;
 804         if (reftable_log_record_is_deletion(r))
 805                 return 0;
 806
 807         oldh = r->value.update.old_hash;
 808         newh = r->value.update.new_hash;
 809         if (!oldh) {
 810                 oldh = zero;
 811         }
 812         if (!newh) {
 813                 newh = zero;
 814         }
 815
 816         if (s.len < 2 * hash_size)
 817                 return -1;
 818
 819         memcpy(s.buf, oldh, hash_size);
 820         memcpy(s.buf + hash_size, newh, hash_size);
 821         string_view_consume(&s, 2 * hash_size);
 822
 823         n = encode_string(r->value.update.name ? r->value.update.name : "", s);
 824         if (n < 0)
 825                 return -1;
 826         string_view_consume(&s, n);
 827
 828         n = encode_string(r->value.update.email ? r->value.update.email : "",
 829                           s);
 830         if (n < 0)
 831                 return -1;
 832         string_view_consume(&s, n);
 833
 834         n = put_var_int(&s, r->value.update.time);
 835         if (n < 0)
 836                 return -1;
 837         string_view_consume(&s, n);
 838
 839         if (s.len < 2)
 840                 return -1;
 841
 842         put_be16(s.buf, r->value.update.tz_offset);
 843         string_view_consume(&s, 2);
 844
 845         n = encode_string(
 846                 r->value.update.message ? r->value.update.message : "", s);
 847         if (n < 0)
 848                 return -1;
 849         string_view_consume(&s, n);
 850
 851         return start.len - s.len;
 852 }
 853
 854 static int reftable_log_record_decode(void *rec, struct strbuf key,
 855                                       uint8_t val_type, struct string_view in,
 856                                       int hash_size)
 857 {
 858         struct string_view start = in;
 859         struct reftable_log_record *r = rec;
 860         uint64_t max = 0;
 861         uint64_t ts = 0;
 862         struct strbuf dest = STRBUF_INIT;
 863         int n;
 864
 865         if (key.len <= 9 || key.buf[key.len - 9] != 0)
 866                 return REFTABLE_FORMAT_ERROR;
 867
 868         r->refname = reftable_realloc(r->refname, key.len - 8);
 869         memcpy(r->refname, key.buf, key.len - 8);
 870         ts = get_be64(key.buf + key.len - 8);
 871
 872         r->update_index = (~max) - ts;
 873
 874         if (val_type != r->value_type) {
 875                 switch (r->value_type) {
 876                 case REFTABLE_LOG_UPDATE:
 877                         FREE_AND_NULL(r->value.update.old_hash);
 878                         FREE_AND_NULL(r->value.update.new_hash);
 879                         FREE_AND_NULL(r->value.update.message);
 880                         FREE_AND_NULL(r->value.update.email);
 881                         FREE_AND_NULL(r->value.update.name);
 882                         break;
 883                 case REFTABLE_LOG_DELETION:
 884                         break;
 885                 }
 886         }
 887
 888         r->value_type = val_type;
 889         if (val_type == REFTABLE_LOG_DELETION)
 890                 return 0;
 891
 892         if (in.len < 2 * hash_size)
 893                 return REFTABLE_FORMAT_ERROR;
 894
 895         r->value.update.old_hash =
 896                 reftable_realloc(r->value.update.old_hash, hash_size);
 897         r->value.update.new_hash =
 898                 reftable_realloc(r->value.update.new_hash, hash_size);
 899
 900         memcpy(r->value.update.old_hash, in.buf, hash_size);
 901         memcpy(r->value.update.new_hash, in.buf + hash_size, hash_size);
 902
 903         string_view_consume(&in, 2 * hash_size);
 904
 905         n = decode_string(&dest, in);
 906         if (n < 0)
 907                 goto done;
 908         string_view_consume(&in, n);
 909
 910         r->value.update.name =
 911                 reftable_realloc(r->value.update.name, dest.len + 1);
 912         memcpy(r->value.update.name, dest.buf, dest.len);
 913         r->value.update.name[dest.len] = 0;
 914
 915         strbuf_reset(&dest);
 916         n = decode_string(&dest, in);
 917         if (n < 0)
 918                 goto done;
 919         string_view_consume(&in, n);
 920
 921         r->value.update.email =
 922                 reftable_realloc(r->value.update.email, dest.len + 1);
 923         memcpy(r->value.update.email, dest.buf, dest.len);
 924         r->value.update.email[dest.len] = 0;
 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         strbuf_reset(&dest);
 939         n = decode_string(&dest, in);
 940         if (n < 0)
 941                 goto done;
 942         string_view_consume(&in, n);
 943
 944         r->value.update.message =
 945                 reftable_realloc(r->value.update.message, dest.len + 1);
 946         memcpy(r->value.update.message, dest.buf, dest.len);
 947         r->value.update.message[dest.len] = 0;
 948
 949         strbuf_release(&dest);
 950         return start.len - in.len;
 951
 952 done:
 953         strbuf_release(&dest);
 954         return REFTABLE_FORMAT_ERROR;
 955 }
 956
 957 static int null_streq(char *a, char *b)
 958 {
 959         char *empty = "";
 960         if (!a)
 961                 a = empty;
 962
 963         if (!b)
 964                 b = empty;
 965
 966         return 0 == strcmp(a, b);
 967 }
 968
 969 static int zero_hash_eq(uint8_t *a, uint8_t *b, int sz)
 970 {
 971         if (!a)
 972                 a = zero;
 973
 974         if (!b)
 975                 b = zero;
 976
 977         return !memcmp(a, b, sz);
 978 }
 979
 980 static int reftable_log_record_equal_void(const void *a,
 981                                           const void *b, int hash_size)
 982 {
 983         return reftable_log_record_equal((struct reftable_log_record *) a,
 984                                          (struct reftable_log_record *) b,
 985                                          hash_size);
 986 }
 987
 988 static int reftable_log_record_cmp_void(const void *_a, const void *_b)
 989 {
 990         const struct reftable_log_record *a = _a;
 991         const struct reftable_log_record *b = _b;
 992         int cmp = strcmp(a->refname, b->refname);
 993         if (cmp)
 994                 return cmp;
 995
 996         /*
 997          * Note that the comparison here is reversed. This is because the
 998          * update index is reversed when comparing keys. For reference, see how
 999          * we handle this in reftable_log_record_key()`.
1000          */
1001         return b->update_index - a->update_index;
1002 }
1003
1004 int reftable_log_record_equal(const struct reftable_log_record *a,
1005                               const struct reftable_log_record *b, int hash_size)
1006 {
1007         if (!(null_streq(a->refname, b->refname) &&
1008               a->update_index == b->update_index &&
1009               a->value_type == b->value_type))
1010                 return 0;
1011
1012         switch (a->value_type) {
1013         case REFTABLE_LOG_DELETION:
1014                 return 1;
1015         case REFTABLE_LOG_UPDATE:
1016                 return null_streq(a->value.update.name, b->value.update.name) &&
1017                        a->value.update.time == b->value.update.time &&
1018                        a->value.update.tz_offset == b->value.update.tz_offset &&
1019                        null_streq(a->value.update.email,
1020                                   b->value.update.email) &&
1021                        null_streq(a->value.update.message,
1022                                   b->value.update.message) &&
1023                        zero_hash_eq(a->value.update.old_hash,
1024                                     b->value.update.old_hash, hash_size) &&
1025                        zero_hash_eq(a->value.update.new_hash,
1026                                     b->value.update.new_hash, hash_size);
1027         }
1028
1029         abort();
1030 }
1031
1032 static int reftable_log_record_is_deletion_void(const void *p)
1033 {
1034         return reftable_log_record_is_deletion(
1035                 (const struct reftable_log_record *)p);
1036 }
1037
1038 static void reftable_log_record_print_void(const void *rec, int hash_size)
1039 {
1040         reftable_log_record_print_sz((struct reftable_log_record*)rec, hash_size);
1041 }
1042
1043 static struct reftable_record_vtable reftable_log_record_vtable = {
1044         .key = &reftable_log_record_key,
1045         .type = BLOCK_TYPE_LOG,
1046         .copy_from = &reftable_log_record_copy_from,
1047         .val_type = &reftable_log_record_val_type,
1048         .encode = &reftable_log_record_encode,
1049         .decode = &reftable_log_record_decode,
1050         .release = &reftable_log_record_release_void,
1051         .is_deletion = &reftable_log_record_is_deletion_void,
1052         .equal = &reftable_log_record_equal_void,
1053         .cmp = &reftable_log_record_cmp_void,
1054         .print = &reftable_log_record_print_void,
1055 };
1056
1057 static void reftable_index_record_key(const void *r, struct strbuf *dest)
1058 {
1059         const struct reftable_index_record *rec = r;
1060         strbuf_reset(dest);
1061         strbuf_addbuf(dest, &rec->last_key);
1062 }
1063
1064 static void reftable_index_record_copy_from(void *rec, const void *src_rec,
1065                                             int hash_size)
1066 {
1067         struct reftable_index_record *dst = rec;
1068         const struct reftable_index_record *src = src_rec;
1069
1070         strbuf_reset(&dst->last_key);
1071         strbuf_addbuf(&dst->last_key, &src->last_key);
1072         dst->offset = src->offset;
1073 }
1074
1075 static void reftable_index_record_release(void *rec)
1076 {
1077         struct reftable_index_record *idx = rec;
1078         strbuf_release(&idx->last_key);
1079 }
1080
1081 static uint8_t reftable_index_record_val_type(const void *rec)
1082 {
1083         return 0;
1084 }
1085
1086 static int reftable_index_record_encode(const void *rec, struct string_view out,
1087                                         int hash_size)
1088 {
1089         const struct reftable_index_record *r =
1090                 (const struct reftable_index_record *)rec;
1091         struct string_view start = out;
1092
1093         int n = put_var_int(&out, r->offset);
1094         if (n < 0)
1095                 return n;
1096
1097         string_view_consume(&out, n);
1098
1099         return start.len - out.len;
1100 }
1101
1102 static int reftable_index_record_decode(void *rec, struct strbuf key,
1103                                         uint8_t val_type, struct string_view in,
1104                                         int hash_size)
1105 {
1106         struct string_view start = in;
1107         struct reftable_index_record *r = rec;
1108         int n = 0;
1109
1110         strbuf_reset(&r->last_key);
1111         strbuf_addbuf(&r->last_key, &key);
1112
1113         n = get_var_int(&r->offset, &in);
1114         if (n < 0)
1115                 return n;
1116
1117         string_view_consume(&in, n);
1118         return start.len - in.len;
1119 }
1120
1121 static int reftable_index_record_equal(const void *a, const void *b, int hash_size)
1122 {
1123         struct reftable_index_record *ia = (struct reftable_index_record *) a;
1124         struct reftable_index_record *ib = (struct reftable_index_record *) b;
1125
1126         return ia->offset == ib->offset && !strbuf_cmp(&ia->last_key, &ib->last_key);
1127 }
1128
1129 static int reftable_index_record_cmp(const void *_a, const void *_b)
1130 {
1131         const struct reftable_index_record *a = _a;
1132         const struct reftable_index_record *b = _b;
1133         return strbuf_cmp(&a->last_key, &b->last_key);
1134 }
1135
1136 static void reftable_index_record_print(const void *rec, int hash_size)
1137 {
1138         const struct reftable_index_record *idx = rec;
1139         /* TODO: escape null chars? */
1140         printf("\"%s\" %" PRIu64 "\n", idx->last_key.buf, idx->offset);
1141 }
1142
1143 static struct reftable_record_vtable reftable_index_record_vtable = {
1144         .key = &reftable_index_record_key,
1145         .type = BLOCK_TYPE_INDEX,
1146         .copy_from = &reftable_index_record_copy_from,
1147         .val_type = &reftable_index_record_val_type,
1148         .encode = &reftable_index_record_encode,
1149         .decode = &reftable_index_record_decode,
1150         .release = &reftable_index_record_release,
1151         .is_deletion = &not_a_deletion,
1152         .equal = &reftable_index_record_equal,
1153         .cmp = &reftable_index_record_cmp,
1154         .print = &reftable_index_record_print,
1155 };
1156
1157 void reftable_record_key(struct reftable_record *rec, struct strbuf *dest)
1158 {
1159         reftable_record_vtable(rec)->key(reftable_record_data(rec), dest);
1160 }
1161
1162 uint8_t reftable_record_type(struct reftable_record *rec)
1163 {
1164         return rec->type;
1165 }
1166
1167 int reftable_record_encode(struct reftable_record *rec, struct string_view dest,
1168                            int hash_size)
1169 {
1170         return reftable_record_vtable(rec)->encode(reftable_record_data(rec),
1171                                                    dest, hash_size);
1172 }
1173
1174 void reftable_record_copy_from(struct reftable_record *rec,
1175                                struct reftable_record *src, int hash_size)
1176 {
1177         assert(src->type == rec->type);
1178
1179         reftable_record_vtable(rec)->copy_from(reftable_record_data(rec),
1180                                                reftable_record_data(src),
1181                                                hash_size);
1182 }
1183
1184 uint8_t reftable_record_val_type(struct reftable_record *rec)
1185 {
1186         return reftable_record_vtable(rec)->val_type(reftable_record_data(rec));
1187 }
1188
1189 int reftable_record_decode(struct reftable_record *rec, struct strbuf key,
1190                            uint8_t extra, struct string_view src, int hash_size)
1191 {
1192         return reftable_record_vtable(rec)->decode(reftable_record_data(rec),
1193                                                    key, extra, src, hash_size);
1194 }
1195
1196 void reftable_record_release(struct reftable_record *rec)
1197 {
1198         reftable_record_vtable(rec)->release(reftable_record_data(rec));
1199 }
1200
1201 int reftable_record_is_deletion(struct reftable_record *rec)
1202 {
1203         return reftable_record_vtable(rec)->is_deletion(
1204                 reftable_record_data(rec));
1205 }
1206
1207 int reftable_record_cmp(struct reftable_record *a, struct reftable_record *b)
1208 {
1209         if (a->type != b->type)
1210                 BUG("cannot compare reftable records of different type");
1211         return reftable_record_vtable(a)->cmp(
1212                 reftable_record_data(a), reftable_record_data(b));
1213 }
1214
1215 int reftable_record_equal(struct reftable_record *a, struct reftable_record *b, int hash_size)
1216 {
1217         if (a->type != b->type)
1218                 return 0;
1219         return reftable_record_vtable(a)->equal(
1220                 reftable_record_data(a), reftable_record_data(b), hash_size);
1221 }
1222
1223 static int hash_equal(const unsigned char *a, const unsigned char *b, int hash_size)
1224 {
1225         if (a && b)
1226                 return !memcmp(a, b, hash_size);
1227
1228         return a == b;
1229 }
1230
1231 int reftable_ref_record_equal(const struct reftable_ref_record *a,
1232                               const struct reftable_ref_record *b, int hash_size)
1233 {
1234         assert(hash_size > 0);
1235         if (!null_streq(a->refname, b->refname))
1236                 return 0;
1237
1238         if (a->update_index != b->update_index ||
1239             a->value_type != b->value_type)
1240                 return 0;
1241
1242         switch (a->value_type) {
1243         case REFTABLE_REF_SYMREF:
1244                 return !strcmp(a->value.symref, b->value.symref);
1245         case REFTABLE_REF_VAL2:
1246                 return hash_equal(a->value.val2.value, b->value.val2.value,
1247                                   hash_size) &&
1248                        hash_equal(a->value.val2.target_value,
1249                                   b->value.val2.target_value, hash_size);
1250         case REFTABLE_REF_VAL1:
1251                 return hash_equal(a->value.val1, b->value.val1, hash_size);
1252         case REFTABLE_REF_DELETION:
1253                 return 1;
1254         default:
1255                 abort();
1256         }
1257 }
1258
1259 int reftable_ref_record_compare_name(const void *a, const void *b)
1260 {
1261         return strcmp(((struct reftable_ref_record *)a)->refname,
1262                       ((struct reftable_ref_record *)b)->refname);
1263 }
1264
1265 int reftable_ref_record_is_deletion(const struct reftable_ref_record *ref)
1266 {
1267         return ref->value_type == REFTABLE_REF_DELETION;
1268 }
1269
1270 int reftable_log_record_compare_key(const void *a, const void *b)
1271 {
1272         const struct reftable_log_record *la = a;
1273         const struct reftable_log_record *lb = b;
1274
1275         int cmp = strcmp(la->refname, lb->refname);
1276         if (cmp)
1277                 return cmp;
1278         if (la->update_index > lb->update_index)
1279                 return -1;
1280         return (la->update_index < lb->update_index) ? 1 : 0;
1281 }
1282
1283 int reftable_log_record_is_deletion(const struct reftable_log_record *log)
1284 {
1285         return (log->value_type == REFTABLE_LOG_DELETION);
1286 }
1287
1288 void string_view_consume(struct string_view *s, int n)
1289 {
1290         s->buf += n;
1291         s->len -= n;
1292 }
1293
1294 static void *reftable_record_data(struct reftable_record *rec)
1295 {
1296         switch (rec->type) {
1297         case BLOCK_TYPE_REF:
1298                 return &rec->u.ref;
1299         case BLOCK_TYPE_LOG:
1300                 return &rec->u.log;
1301         case BLOCK_TYPE_INDEX:
1302                 return &rec->u.idx;
1303         case BLOCK_TYPE_OBJ:
1304                 return &rec->u.obj;
1305         }
1306         abort();
1307 }
1308
1309 static struct reftable_record_vtable *
1310 reftable_record_vtable(struct reftable_record *rec)
1311 {
1312         switch (rec->type) {
1313         case BLOCK_TYPE_REF:
1314                 return &reftable_ref_record_vtable;
1315         case BLOCK_TYPE_LOG:
1316                 return &reftable_log_record_vtable;
1317         case BLOCK_TYPE_INDEX:
1318                 return &reftable_index_record_vtable;
1319         case BLOCK_TYPE_OBJ:
1320                 return &reftable_obj_record_vtable;
1321         }
1322         abort();
1323 }
1324
1325 void reftable_record_init(struct reftable_record *rec, uint8_t typ)
1326 {
1327         memset(rec, 0, sizeof(*rec));
1328         rec->type = typ;
1329
1330         switch (typ) {
1331         case BLOCK_TYPE_REF:
1332         case BLOCK_TYPE_LOG:
1333         case BLOCK_TYPE_OBJ:
1334                 return;
1335         case BLOCK_TYPE_INDEX:
1336                 strbuf_init(&rec->u.idx.last_key, 0);
1337                 return;
1338         default:
1339                 BUG("unhandled record type");
1340         }
1341 }
1342
1343 void reftable_record_print(struct reftable_record *rec, int hash_size)
1344 {
1345         printf("'%c': ", rec->type);
1346         reftable_record_vtable(rec)->print(reftable_record_data(rec), hash_size);
1347 }