git.oblomov.eu Git - git/blob - cache-tree.c

   1 #include "cache.h"
   2 #include "lockfile.h"
   3 #include "tree.h"
   4 #include "tree-walk.h"
   5 #include "cache-tree.h"
   6 #include "object-store.h"
   7 #include "replace-object.h"
   8
   9 #ifndef DEBUG
  10 #define DEBUG 0
  11 #endif
  12
  13 struct cache_tree *cache_tree(void)
  14 {
  15         struct cache_tree *it = xcalloc(1, sizeof(struct cache_tree));
  16         it->entry_count = -1;
  17         return it;
  18 }
  19
  20 void cache_tree_free(struct cache_tree **it_p)
  21 {
  22         int i;
  23         struct cache_tree *it = *it_p;
  24
  25         if (!it)
  26                 return;
  27         for (i = 0; i < it->subtree_nr; i++)
  28                 if (it->down[i]) {
  29                         cache_tree_free(&it->down[i]->cache_tree);
  30                         free(it->down[i]);
  31                 }
  32         free(it->down);
  33         free(it);
  34         *it_p = NULL;
  35 }
  36
  37 static int subtree_name_cmp(const char *one, int onelen,
  38                             const char *two, int twolen)
  39 {
  40         if (onelen < twolen)
  41                 return -1;
  42         if (twolen < onelen)
  43                 return 1;
  44         return memcmp(one, two, onelen);
  45 }
  46
  47 static int subtree_pos(struct cache_tree *it, const char *path, int pathlen)
  48 {
  49         struct cache_tree_sub **down = it->down;
  50         int lo, hi;
  51         lo = 0;
  52         hi = it->subtree_nr;
  53         while (lo < hi) {
  54                 int mi = lo + (hi - lo) / 2;
  55                 struct cache_tree_sub *mdl = down[mi];
  56                 int cmp = subtree_name_cmp(path, pathlen,
  57                                            mdl->name, mdl->namelen);
  58                 if (!cmp)
  59                         return mi;
  60                 if (cmp < 0)
  61                         hi = mi;
  62                 else
  63                         lo = mi + 1;
  64         }
  65         return -lo-1;
  66 }
  67
  68 static struct cache_tree_sub *find_subtree(struct cache_tree *it,
  69                                            const char *path,
  70                                            int pathlen,
  71                                            int create)
  72 {
  73         struct cache_tree_sub *down;
  74         int pos = subtree_pos(it, path, pathlen);
  75         if (0 <= pos)
  76                 return it->down[pos];
  77         if (!create)
  78                 return NULL;
  79
  80         pos = -pos-1;
  81         ALLOC_GROW(it->down, it->subtree_nr + 1, it->subtree_alloc);
  82         it->subtree_nr++;
  83
  84         FLEX_ALLOC_MEM(down, name, path, pathlen);
  85         down->cache_tree = NULL;
  86         down->namelen = pathlen;
  87
  88         if (pos < it->subtree_nr)
  89                 MOVE_ARRAY(it->down + pos + 1, it->down + pos,
  90                            it->subtree_nr - pos - 1);
  91         it->down[pos] = down;
  92         return down;
  93 }
  94
  95 struct cache_tree_sub *cache_tree_sub(struct cache_tree *it, const char *path)
  96 {
  97         int pathlen = strlen(path);
  98         return find_subtree(it, path, pathlen, 1);
  99 }
 100
 101 static int do_invalidate_path(struct cache_tree *it, const char *path)
 102 {
 103         /* a/b/c
 104          * ==> invalidate self
 105          * ==> find "a", have it invalidate "b/c"
 106          * a
 107          * ==> invalidate self
 108          * ==> if "a" exists as a subtree, remove it.
 109          */
 110         const char *slash;
 111         int namelen;
 112         struct cache_tree_sub *down;
 113
 114 #if DEBUG
 115         fprintf(stderr, "cache-tree invalidate <%s>\n", path);
 116 #endif
 117
 118         if (!it)
 119                 return 0;
 120         slash = strchrnul(path, '/');
 121         namelen = slash - path;
 122         it->entry_count = -1;
 123         if (!*slash) {
 124                 int pos;
 125                 pos = subtree_pos(it, path, namelen);
 126                 if (0 <= pos) {
 127                         cache_tree_free(&it->down[pos]->cache_tree);
 128                         free(it->down[pos]);
 129                         /* 0 1 2 3 4 5
 130                          *       ^     ^subtree_nr = 6
 131                          *       pos
 132                          * move 4 and 5 up one place (2 entries)
 133                          * 2 = 6 - 3 - 1 = subtree_nr - pos - 1
 134                          */
 135                         MOVE_ARRAY(it->down + pos, it->down + pos + 1,
 136                                    it->subtree_nr - pos - 1);
 137                         it->subtree_nr--;
 138                 }
 139                 return 1;
 140         }
 141         down = find_subtree(it, path, namelen, 0);
 142         if (down)
 143                 do_invalidate_path(down->cache_tree, slash + 1);
 144         return 1;
 145 }
 146
 147 void cache_tree_invalidate_path(struct index_state *istate, const char *path)
 148 {
 149         if (do_invalidate_path(istate->cache_tree, path))
 150                 istate->cache_changed |= CACHE_TREE_CHANGED;
 151 }
 152
 153 static int verify_cache(struct cache_entry **cache,
 154                         int entries, int flags)
 155 {
 156         int i, funny;
 157         int silent = flags & WRITE_TREE_SILENT;
 158
 159         /* Verify that the tree is merged */
 160         funny = 0;
 161         for (i = 0; i < entries; i++) {
 162                 const struct cache_entry *ce = cache[i];
 163                 if (ce_stage(ce)) {
 164                         if (silent)
 165                                 return -1;
 166                         if (10 < ++funny) {
 167                                 fprintf(stderr, "...\n");
 168                                 break;
 169                         }
 170                         fprintf(stderr, "%s: unmerged (%s)\n",
 171                                 ce->name, oid_to_hex(&ce->oid));
 172                 }
 173         }
 174         if (funny)
 175                 return -1;
 176
 177         /* Also verify that the cache does not have path and path/file
 178          * at the same time.  At this point we know the cache has only
 179          * stage 0 entries.
 180          */
 181         funny = 0;
 182         for (i = 0; i < entries - 1; i++) {
 183                 /* path/file always comes after path because of the way
 184                  * the cache is sorted.  Also path can appear only once,
 185                  * which means conflicting one would immediately follow.
 186                  */
 187                 const char *this_name = cache[i]->name;
 188                 const char *next_name = cache[i+1]->name;
 189                 int this_len = strlen(this_name);
 190                 if (this_len < strlen(next_name) &&
 191                     strncmp(this_name, next_name, this_len) == 0 &&
 192                     next_name[this_len] == '/') {
 193                         if (10 < ++funny) {
 194                                 fprintf(stderr, "...\n");
 195                                 break;
 196                         }
 197                         fprintf(stderr, "You have both %s and %s\n",
 198                                 this_name, next_name);
 199                 }
 200         }
 201         if (funny)
 202                 return -1;
 203         return 0;
 204 }
 205
 206 static void discard_unused_subtrees(struct cache_tree *it)
 207 {
 208         struct cache_tree_sub **down = it->down;
 209         int nr = it->subtree_nr;
 210         int dst, src;
 211         for (dst = src = 0; src < nr; src++) {
 212                 struct cache_tree_sub *s = down[src];
 213                 if (s->used)
 214                         down[dst++] = s;
 215                 else {
 216                         cache_tree_free(&s->cache_tree);
 217                         free(s);
 218                         it->subtree_nr--;
 219                 }
 220         }
 221 }
 222
 223 int cache_tree_fully_valid(struct cache_tree *it)
 224 {
 225         int i;
 226         if (!it)
 227                 return 0;
 228         if (it->entry_count < 0 || !has_object_file(&it->oid))
 229                 return 0;
 230         for (i = 0; i < it->subtree_nr; i++) {
 231                 if (!cache_tree_fully_valid(it->down[i]->cache_tree))
 232                         return 0;
 233         }
 234         return 1;
 235 }
 236
 237 static int update_one(struct cache_tree *it,
 238                       struct cache_entry **cache,
 239                       int entries,
 240                       const char *base,
 241                       int baselen,
 242                       int *skip_count,
 243                       int flags)
 244 {
 245         struct strbuf buffer;
 246         int missing_ok = flags & WRITE_TREE_MISSING_OK;
 247         int dryrun = flags & WRITE_TREE_DRY_RUN;
 248         int repair = flags & WRITE_TREE_REPAIR;
 249         int to_invalidate = 0;
 250         int i;
 251
 252         assert(!(dryrun && repair));
 253
 254         *skip_count = 0;
 255
 256         if (0 <= it->entry_count && has_object_file(&it->oid))
 257                 return it->entry_count;
 258
 259         /*
 260          * We first scan for subtrees and update them; we start by
 261          * marking existing subtrees -- the ones that are unmarked
 262          * should not be in the result.
 263          */
 264         for (i = 0; i < it->subtree_nr; i++)
 265                 it->down[i]->used = 0;
 266
 267         /*
 268          * Find the subtrees and update them.
 269          */
 270         i = 0;
 271         while (i < entries) {
 272                 const struct cache_entry *ce = cache[i];
 273                 struct cache_tree_sub *sub;
 274                 const char *path, *slash;
 275                 int pathlen, sublen, subcnt, subskip;
 276
 277                 path = ce->name;
 278                 pathlen = ce_namelen(ce);
 279                 if (pathlen <= baselen || memcmp(base, path, baselen))
 280                         break; /* at the end of this level */
 281
 282                 slash = strchr(path + baselen, '/');
 283                 if (!slash) {
 284                         i++;
 285                         continue;
 286                 }
 287                 /*
 288                  * a/bbb/c (base = a/, slash = /c)
 289                  * ==>
 290                  * path+baselen = bbb/c, sublen = 3
 291                  */
 292                 sublen = slash - (path + baselen);
 293                 sub = find_subtree(it, path + baselen, sublen, 1);
 294                 if (!sub->cache_tree)
 295                         sub->cache_tree = cache_tree();
 296                 subcnt = update_one(sub->cache_tree,
 297                                     cache + i, entries - i,
 298                                     path,
 299                                     baselen + sublen + 1,
 300                                     &subskip,
 301                                     flags);
 302                 if (subcnt < 0)
 303                         return subcnt;
 304                 if (!subcnt)
 305                         die("index cache-tree records empty sub-tree");
 306                 i += subcnt;
 307                 sub->count = subcnt; /* to be used in the next loop */
 308                 *skip_count += subskip;
 309                 sub->used = 1;
 310         }
 311
 312         discard_unused_subtrees(it);
 313
 314         /*
 315          * Then write out the tree object for this level.
 316          */
 317         strbuf_init(&buffer, 8192);
 318
 319         i = 0;
 320         while (i < entries) {
 321                 const struct cache_entry *ce = cache[i];
 322                 struct cache_tree_sub *sub = NULL;
 323                 const char *path, *slash;
 324                 int pathlen, entlen;
 325                 const struct object_id *oid;
 326                 unsigned mode;
 327                 int expected_missing = 0;
 328                 int contains_ita = 0;
 329                 int ce_missing_ok;
 330
 331                 path = ce->name;
 332                 pathlen = ce_namelen(ce);
 333                 if (pathlen <= baselen || memcmp(base, path, baselen))
 334                         break; /* at the end of this level */
 335
 336                 slash = strchr(path + baselen, '/');
 337                 if (slash) {
 338                         entlen = slash - (path + baselen);
 339                         sub = find_subtree(it, path + baselen, entlen, 0);
 340                         if (!sub)
 341                                 die("cache-tree.c: '%.*s' in '%s' not found",
 342                                     entlen, path + baselen, path);
 343                         i += sub->count;
 344                         oid = &sub->cache_tree->oid;
 345                         mode = S_IFDIR;
 346                         contains_ita = sub->cache_tree->entry_count < 0;
 347                         if (contains_ita) {
 348                                 to_invalidate = 1;
 349                                 expected_missing = 1;
 350                         }
 351                 }
 352                 else {
 353                         oid = &ce->oid;
 354                         mode = ce->ce_mode;
 355                         entlen = pathlen - baselen;
 356                         i++;
 357                 }
 358
 359                 ce_missing_ok = mode == S_IFGITLINK || missing_ok ||
 360                         (repository_format_partial_clone &&
 361                          ce_skip_worktree(ce));
 362                 if (is_null_oid(oid) ||
 363                     (!ce_missing_ok && !has_object_file(oid))) {
 364                         strbuf_release(&buffer);
 365                         if (expected_missing)
 366                                 return -1;
 367                         return error("invalid object %06o %s for '%.*s'",
 368                                 mode, oid_to_hex(oid), entlen+baselen, path);
 369                 }
 370
 371                 /*
 372                  * CE_REMOVE entries are removed before the index is
 373                  * written to disk. Skip them to remain consistent
 374                  * with the future on-disk index.
 375                  */
 376                 if (ce->ce_flags & CE_REMOVE) {
 377                         *skip_count = *skip_count + 1;
 378                         continue;
 379                 }
 380
 381                 /*
 382                  * CE_INTENT_TO_ADD entries exist on on-disk index but
 383                  * they are not part of generated trees. Invalidate up
 384                  * to root to force cache-tree users to read elsewhere.
 385                  */
 386                 if (!sub && ce_intent_to_add(ce)) {
 387                         to_invalidate = 1;
 388                         continue;
 389                 }
 390
 391                 /*
 392                  * "sub" can be an empty tree if all subentries are i-t-a.
 393                  */
 394                 if (contains_ita && is_empty_tree_oid(oid))
 395                         continue;
 396
 397                 strbuf_grow(&buffer, entlen + 100);
 398                 strbuf_addf(&buffer, "%o %.*s%c", mode, entlen, path + baselen, '\0');
 399                 strbuf_add(&buffer, oid->hash, the_hash_algo->rawsz);
 400
 401 #if DEBUG
 402                 fprintf(stderr, "cache-tree update-one %o %.*s\n",
 403                         mode, entlen, path + baselen);
 404 #endif
 405         }
 406
 407         if (repair) {
 408                 struct object_id oid;
 409                 hash_object_file(buffer.buf, buffer.len, tree_type, &oid);
 410                 if (has_object_file(&oid))
 411                         oidcpy(&it->oid, &oid);
 412                 else
 413                         to_invalidate = 1;
 414         } else if (dryrun) {
 415                 hash_object_file(buffer.buf, buffer.len, tree_type, &it->oid);
 416         } else if (write_object_file(buffer.buf, buffer.len, tree_type,
 417                                      &it->oid)) {
 418                 strbuf_release(&buffer);
 419                 return -1;
 420         }
 421
 422         strbuf_release(&buffer);
 423         it->entry_count = to_invalidate ? -1 : i - *skip_count;
 424 #if DEBUG
 425         fprintf(stderr, "cache-tree update-one (%d ent, %d subtree) %s\n",
 426                 it->entry_count, it->subtree_nr,
 427                 oid_to_hex(&it->oid));
 428 #endif
 429         return i;
 430 }
 431
 432 int cache_tree_update(struct index_state *istate, int flags)
 433 {
 434         struct cache_tree *it = istate->cache_tree;
 435         struct cache_entry **cache = istate->cache;
 436         int entries = istate->cache_nr;
 437         int skip, i = verify_cache(cache, entries, flags);
 438
 439         if (i)
 440                 return i;
 441         trace_performance_enter();
 442         i = update_one(it, cache, entries, "", 0, &skip, flags);
 443         trace_performance_leave("cache_tree_update");
 444         if (i < 0)
 445                 return i;
 446         istate->cache_changed |= CACHE_TREE_CHANGED;
 447         return 0;
 448 }
 449
 450 static void write_one(struct strbuf *buffer, struct cache_tree *it,
 451                       const char *path, int pathlen)
 452 {
 453         int i;
 454
 455         /* One "cache-tree" entry consists of the following:
 456          * path (NUL terminated)
 457          * entry_count, subtree_nr ("%d %d\n")
 458          * tree-sha1 (missing if invalid)
 459          * subtree_nr "cache-tree" entries for subtrees.
 460          */
 461         strbuf_grow(buffer, pathlen + 100);
 462         strbuf_add(buffer, path, pathlen);
 463         strbuf_addf(buffer, "%c%d %d\n", 0, it->entry_count, it->subtree_nr);
 464
 465 #if DEBUG
 466         if (0 <= it->entry_count)
 467                 fprintf(stderr, "cache-tree <%.*s> (%d ent, %d subtree) %s\n",
 468                         pathlen, path, it->entry_count, it->subtree_nr,
 469                         oid_to_hex(&it->oid));
 470         else
 471                 fprintf(stderr, "cache-tree <%.*s> (%d subtree) invalid\n",
 472                         pathlen, path, it->subtree_nr);
 473 #endif
 474
 475         if (0 <= it->entry_count) {
 476                 strbuf_add(buffer, it->oid.hash, the_hash_algo->rawsz);
 477         }
 478         for (i = 0; i < it->subtree_nr; i++) {
 479                 struct cache_tree_sub *down = it->down[i];
 480                 if (i) {
 481                         struct cache_tree_sub *prev = it->down[i-1];
 482                         if (subtree_name_cmp(down->name, down->namelen,
 483                                              prev->name, prev->namelen) <= 0)
 484                                 die("fatal - unsorted cache subtree");
 485                 }
 486                 write_one(buffer, down->cache_tree, down->name, down->namelen);
 487         }
 488 }
 489
 490 void cache_tree_write(struct strbuf *sb, struct cache_tree *root)
 491 {
 492         write_one(sb, root, "", 0);
 493 }
 494
 495 static struct cache_tree *read_one(const char **buffer, unsigned long *size_p)
 496 {
 497         const char *buf = *buffer;
 498         unsigned long size = *size_p;
 499         const char *cp;
 500         char *ep;
 501         struct cache_tree *it;
 502         int i, subtree_nr;
 503         const unsigned rawsz = the_hash_algo->rawsz;
 504
 505         it = NULL;
 506         /* skip name, but make sure name exists */
 507         while (size && *buf) {
 508                 size--;
 509                 buf++;
 510         }
 511         if (!size)
 512                 goto free_return;
 513         buf++; size--;
 514         it = cache_tree();
 515
 516         cp = buf;
 517         it->entry_count = strtol(cp, &ep, 10);
 518         if (cp == ep)
 519                 goto free_return;
 520         cp = ep;
 521         subtree_nr = strtol(cp, &ep, 10);
 522         if (cp == ep)
 523                 goto free_return;
 524         while (size && *buf && *buf != '\n') {
 525                 size--;
 526                 buf++;
 527         }
 528         if (!size)
 529                 goto free_return;
 530         buf++; size--;
 531         if (0 <= it->entry_count) {
 532                 if (size < rawsz)
 533                         goto free_return;
 534                 oidread(&it->oid, (const unsigned char *)buf);
 535                 buf += rawsz;
 536                 size -= rawsz;
 537         }
 538
 539 #if DEBUG
 540         if (0 <= it->entry_count)
 541                 fprintf(stderr, "cache-tree <%s> (%d ent, %d subtree) %s\n",
 542                         *buffer, it->entry_count, subtree_nr,
 543                         oid_to_hex(&it->oid));
 544         else
 545                 fprintf(stderr, "cache-tree <%s> (%d subtrees) invalid\n",
 546                         *buffer, subtree_nr);
 547 #endif
 548
 549         /*
 550          * Just a heuristic -- we do not add directories that often but
 551          * we do not want to have to extend it immediately when we do,
 552          * hence +2.
 553          */
 554         it->subtree_alloc = subtree_nr + 2;
 555         it->down = xcalloc(it->subtree_alloc, sizeof(struct cache_tree_sub *));
 556         for (i = 0; i < subtree_nr; i++) {
 557                 /* read each subtree */
 558                 struct cache_tree *sub;
 559                 struct cache_tree_sub *subtree;
 560                 const char *name = buf;
 561
 562                 sub = read_one(&buf, &size);
 563                 if (!sub)
 564                         goto free_return;
 565                 subtree = cache_tree_sub(it, name);
 566                 subtree->cache_tree = sub;
 567         }
 568         if (subtree_nr != it->subtree_nr)
 569                 die("cache-tree: internal error");
 570         *buffer = buf;
 571         *size_p = size;
 572         return it;
 573
 574  free_return:
 575         cache_tree_free(&it);
 576         return NULL;
 577 }
 578
 579 struct cache_tree *cache_tree_read(const char *buffer, unsigned long size)
 580 {
 581         if (buffer[0])
 582                 return NULL; /* not the whole tree */
 583         return read_one(&buffer, &size);
 584 }
 585
 586 static struct cache_tree *cache_tree_find(struct cache_tree *it, const char *path)
 587 {
 588         if (!it)
 589                 return NULL;
 590         while (*path) {
 591                 const char *slash;
 592                 struct cache_tree_sub *sub;
 593
 594                 slash = strchrnul(path, '/');
 595                 /*
 596                  * Between path and slash is the name of the subtree
 597                  * to look for.
 598                  */
 599                 sub = find_subtree(it, path, slash - path, 0);
 600                 if (!sub)
 601                         return NULL;
 602                 it = sub->cache_tree;
 603
 604                 path = slash;
 605                 while (*path == '/')
 606                         path++;
 607         }
 608         return it;
 609 }
 610
 611 int write_index_as_tree(struct object_id *oid, struct index_state *index_state, const char *index_path, int flags, const char *prefix)
 612 {
 613         int entries, was_valid;
 614         struct lock_file lock_file = LOCK_INIT;
 615         int ret = 0;
 616
 617         hold_lock_file_for_update(&lock_file, index_path, LOCK_DIE_ON_ERROR);
 618
 619         entries = read_index_from(index_state, index_path, get_git_dir());
 620         if (entries < 0) {
 621                 ret = WRITE_TREE_UNREADABLE_INDEX;
 622                 goto out;
 623         }
 624         if (flags & WRITE_TREE_IGNORE_CACHE_TREE)
 625                 cache_tree_free(&index_state->cache_tree);
 626
 627         if (!index_state->cache_tree)
 628                 index_state->cache_tree = cache_tree();
 629
 630         was_valid = cache_tree_fully_valid(index_state->cache_tree);
 631         if (!was_valid) {
 632                 if (cache_tree_update(index_state, flags) < 0) {
 633                         ret = WRITE_TREE_UNMERGED_INDEX;
 634                         goto out;
 635                 }
 636                 write_locked_index(index_state, &lock_file, COMMIT_LOCK);
 637                 /* Not being able to write is fine -- we are only interested
 638                  * in updating the cache-tree part, and if the next caller
 639                  * ends up using the old index with unupdated cache-tree part
 640                  * it misses the work we did here, but that is just a
 641                  * performance penalty and not a big deal.
 642                  */
 643         }
 644
 645         if (prefix) {
 646                 struct cache_tree *subtree;
 647                 subtree = cache_tree_find(index_state->cache_tree, prefix);
 648                 if (!subtree) {
 649                         ret = WRITE_TREE_PREFIX_ERROR;
 650                         goto out;
 651                 }
 652                 oidcpy(oid, &subtree->oid);
 653         }
 654         else
 655                 oidcpy(oid, &index_state->cache_tree->oid);
 656
 657 out:
 658         rollback_lock_file(&lock_file);
 659         return ret;
 660 }
 661
 662 static void prime_cache_tree_rec(struct repository *r,
 663                                  struct cache_tree *it,
 664                                  struct tree *tree)
 665 {
 666         struct tree_desc desc;
 667         struct name_entry entry;
 668         int cnt;
 669
 670         oidcpy(&it->oid, &tree->object.oid);
 671         init_tree_desc(&desc, tree->buffer, tree->size);
 672         cnt = 0;
 673         while (tree_entry(&desc, &entry)) {
 674                 if (!S_ISDIR(entry.mode))
 675                         cnt++;
 676                 else {
 677                         struct cache_tree_sub *sub;
 678                         struct tree *subtree = lookup_tree(r, &entry.oid);
 679                         if (!subtree->object.parsed)
 680                                 parse_tree(subtree);
 681                         sub = cache_tree_sub(it, entry.path);
 682                         sub->cache_tree = cache_tree();
 683                         prime_cache_tree_rec(r, sub->cache_tree, subtree);
 684                         cnt += sub->cache_tree->entry_count;
 685                 }
 686         }
 687         it->entry_count = cnt;
 688 }
 689
 690 void prime_cache_tree(struct repository *r,
 691                       struct index_state *istate,
 692                       struct tree *tree)
 693 {
 694         cache_tree_free(&istate->cache_tree);
 695         istate->cache_tree = cache_tree();
 696         prime_cache_tree_rec(r, istate->cache_tree, tree);
 697         istate->cache_changed |= CACHE_TREE_CHANGED;
 698 }
 699
 700 /*
 701  * find the cache_tree that corresponds to the current level without
 702  * exploding the full path into textual form.  The root of the
 703  * cache tree is given as "root", and our current level is "info".
 704  * (1) When at root level, info->prev is NULL, so it is "root" itself.
 705  * (2) Otherwise, find the cache_tree that corresponds to one level
 706  *     above us, and find ourselves in there.
 707  */
 708 static struct cache_tree *find_cache_tree_from_traversal(struct cache_tree *root,
 709                                                          struct traverse_info *info)
 710 {
 711         struct cache_tree *our_parent;
 712
 713         if (!info->prev)
 714                 return root;
 715         our_parent = find_cache_tree_from_traversal(root, info->prev);
 716         return cache_tree_find(our_parent, info->name.path);
 717 }
 718
 719 int cache_tree_matches_traversal(struct cache_tree *root,
 720                                  struct name_entry *ent,
 721                                  struct traverse_info *info)
 722 {
 723         struct cache_tree *it;
 724
 725         it = find_cache_tree_from_traversal(root, info);
 726         it = cache_tree_find(it, ent->path);
 727         if (it && it->entry_count > 0 && oideq(&ent->oid, &it->oid))
 728                 return it->entry_count;
 729         return 0;
 730 }
 731
 732 static void verify_one(struct repository *r,
 733                        struct index_state *istate,
 734                        struct cache_tree *it,
 735                        struct strbuf *path)
 736 {
 737         int i, pos, len = path->len;
 738         struct strbuf tree_buf = STRBUF_INIT;
 739         struct object_id new_oid;
 740
 741         for (i = 0; i < it->subtree_nr; i++) {
 742                 strbuf_addf(path, "%s/", it->down[i]->name);
 743                 verify_one(r, istate, it->down[i]->cache_tree, path);
 744                 strbuf_setlen(path, len);
 745         }
 746
 747         if (it->entry_count < 0 ||
 748             /* no verification on tests (t7003) that replace trees */
 749             lookup_replace_object(r, &it->oid) != &it->oid)
 750                 return;
 751
 752         if (path->len) {
 753                 pos = index_name_pos(istate, path->buf, path->len);
 754                 pos = -pos - 1;
 755         } else {
 756                 pos = 0;
 757         }
 758
 759         i = 0;
 760         while (i < it->entry_count) {
 761                 struct cache_entry *ce = istate->cache[pos + i];
 762                 const char *slash;
 763                 struct cache_tree_sub *sub = NULL;
 764                 const struct object_id *oid;
 765                 const char *name;
 766                 unsigned mode;
 767                 int entlen;
 768
 769                 if (ce->ce_flags & (CE_STAGEMASK | CE_INTENT_TO_ADD | CE_REMOVE))
 770                         BUG("%s with flags 0x%x should not be in cache-tree",
 771                             ce->name, ce->ce_flags);
 772                 name = ce->name + path->len;
 773                 slash = strchr(name, '/');
 774                 if (slash) {
 775                         entlen = slash - name;
 776                         sub = find_subtree(it, ce->name + path->len, entlen, 0);
 777                         if (!sub || sub->cache_tree->entry_count < 0)
 778                                 BUG("bad subtree '%.*s'", entlen, name);
 779                         oid = &sub->cache_tree->oid;
 780                         mode = S_IFDIR;
 781                         i += sub->cache_tree->entry_count;
 782                 } else {
 783                         oid = &ce->oid;
 784                         mode = ce->ce_mode;
 785                         entlen = ce_namelen(ce) - path->len;
 786                         i++;
 787                 }
 788                 strbuf_addf(&tree_buf, "%o %.*s%c", mode, entlen, name, '\0');
 789                 strbuf_add(&tree_buf, oid->hash, the_hash_algo->rawsz);
 790         }
 791         hash_object_file(tree_buf.buf, tree_buf.len, tree_type, &new_oid);
 792         if (!oideq(&new_oid, &it->oid))
 793                 BUG("cache-tree for path %.*s does not match. "
 794                     "Expected %s got %s", len, path->buf,
 795                     oid_to_hex(&new_oid), oid_to_hex(&it->oid));
 796         strbuf_setlen(path, len);
 797         strbuf_release(&tree_buf);
 798 }
 799
 800 void cache_tree_verify(struct repository *r, struct index_state *istate)
 801 {
 802         struct strbuf path = STRBUF_INIT;
 803
 804         if (!istate->cache_tree)
 805                 return;
 806         verify_one(r, istate, istate->cache_tree, &path);
 807         strbuf_release(&path);
 808 }