git.oblomov.eu Git - git/blob - diff-lib.c

   1 /*
   2  * Copyright (C) 2005 Junio C Hamano
   3  */
   4 #include "cache.h"
   5 #include "quote.h"
   6 #include "commit.h"
   7 #include "diff.h"
   8 #include "diffcore.h"
   9 #include "revision.h"
  10 #include "cache-tree.h"
  11 #include "unpack-trees.h"
  12 #include "refs.h"
  13 #include "submodule.h"
  14 #include "dir.h"
  15 #include "fsmonitor.h"
  16 #include "commit-reach.h"
  17
  18 /*
  19  * diff-files
  20  */
  21
  22 /*
  23  * Has the work tree entity been removed?
  24  *
  25  * Return 1 if it was removed from the work tree, 0 if an entity to be
  26  * compared with the cache entry ce still exists (the latter includes
  27  * the case where a directory that is not a submodule repository
  28  * exists for ce that is a submodule -- it is a submodule that is not
  29  * checked out).  Return negative for an error.
  30  */
  31 static int check_removed(const struct cache_entry *ce, struct stat *st)
  32 {
  33         if (lstat(ce->name, st) < 0) {
  34                 if (!is_missing_file_error(errno))
  35                         return -1;
  36                 return 1;
  37         }
  38         if (has_symlink_leading_path(ce->name, ce_namelen(ce)))
  39                 return 1;
  40         if (S_ISDIR(st->st_mode)) {
  41                 struct object_id sub;
  42
  43                 /*
  44                  * If ce is already a gitlink, we can have a plain
  45                  * directory (i.e. the submodule is not checked out),
  46                  * or a checked out submodule.  Either case this is not
  47                  * a case where something was removed from the work tree,
  48                  * so we will return 0.
  49                  *
  50                  * Otherwise, if the directory is not a submodule
  51                  * repository, that means ce which was a blob turned into
  52                  * a directory --- the blob was removed!
  53                  */
  54                 if (!S_ISGITLINK(ce->ce_mode) &&
  55                     resolve_gitlink_ref(ce->name, "HEAD", &sub))
  56                         return 1;
  57         }
  58         return 0;
  59 }
  60
  61 /*
  62  * Has a file changed or has a submodule new commits or a dirty work tree?
  63  *
  64  * Return 1 when changes are detected, 0 otherwise. If the DIRTY_SUBMODULES
  65  * option is set, the caller does not only want to know if a submodule is
  66  * modified at all but wants to know all the conditions that are met (new
  67  * commits, untracked content and/or modified content).
  68  */
  69 static int match_stat_with_submodule(struct diff_options *diffopt,
  70                                      const struct cache_entry *ce,
  71                                      struct stat *st, unsigned ce_option,
  72                                      unsigned *dirty_submodule)
  73 {
  74         int changed = ie_match_stat(diffopt->repo->index, ce, st, ce_option);
  75         if (S_ISGITLINK(ce->ce_mode)) {
  76                 struct diff_flags orig_flags = diffopt->flags;
  77                 if (!diffopt->flags.override_submodule_config)
  78                         set_diffopt_flags_from_submodule_config(diffopt, ce->name);
  79                 if (diffopt->flags.ignore_submodules)
  80                         changed = 0;
  81                 else if (!diffopt->flags.ignore_dirty_submodules &&
  82                          (!changed || diffopt->flags.dirty_submodules))
  83                         *dirty_submodule = is_submodule_modified(ce->name,
  84                                                                  diffopt->flags.ignore_untracked_in_submodules);
  85                 diffopt->flags = orig_flags;
  86         }
  87         return changed;
  88 }
  89
  90 int run_diff_files(struct rev_info *revs, unsigned int option)
  91 {
  92         int entries, i;
  93         int diff_unmerged_stage = revs->max_count;
  94         unsigned ce_option = ((option & DIFF_RACY_IS_MODIFIED)
  95                               ? CE_MATCH_RACY_IS_DIRTY : 0);
  96         uint64_t start = getnanotime();
  97         struct index_state *istate = revs->diffopt.repo->index;
  98
  99         diff_set_mnemonic_prefix(&revs->diffopt, "i/", "w/");
 100
 101         refresh_fsmonitor(istate);
 102
 103         if (diff_unmerged_stage < 0)
 104                 diff_unmerged_stage = 2;
 105         entries = istate->cache_nr;
 106         for (i = 0; i < entries; i++) {
 107                 unsigned int oldmode, newmode;
 108                 struct cache_entry *ce = istate->cache[i];
 109                 int changed;
 110                 unsigned dirty_submodule = 0;
 111                 const struct object_id *old_oid, *new_oid;
 112
 113                 if (diff_can_quit_early(&revs->diffopt))
 114                         break;
 115
 116                 if (!ce_path_match(istate, ce, &revs->prune_data, NULL))
 117                         continue;
 118
 119                 if (ce_stage(ce)) {
 120                         struct combine_diff_path *dpath;
 121                         struct diff_filepair *pair;
 122                         unsigned int wt_mode = 0;
 123                         int num_compare_stages = 0;
 124                         size_t path_len;
 125                         struct stat st;
 126
 127                         path_len = ce_namelen(ce);
 128
 129                         dpath = xmalloc(combine_diff_path_size(5, path_len));
 130                         dpath->path = (char *) &(dpath->parent[5]);
 131
 132                         dpath->next = NULL;
 133                         memcpy(dpath->path, ce->name, path_len);
 134                         dpath->path[path_len] = '\0';
 135                         oidclr(&dpath->oid);
 136                         memset(&(dpath->parent[0]), 0,
 137                                sizeof(struct combine_diff_parent)*5);
 138
 139                         changed = check_removed(ce, &st);
 140                         if (!changed)
 141                                 wt_mode = ce_mode_from_stat(ce, st.st_mode);
 142                         else {
 143                                 if (changed < 0) {
 144                                         perror(ce->name);
 145                                         continue;
 146                                 }
 147                                 wt_mode = 0;
 148                         }
 149                         dpath->mode = wt_mode;
 150
 151                         while (i < entries) {
 152                                 struct cache_entry *nce = istate->cache[i];
 153                                 int stage;
 154
 155                                 if (strcmp(ce->name, nce->name))
 156                                         break;
 157
 158                                 /* Stage #2 (ours) is the first parent,
 159                                  * stage #3 (theirs) is the second.
 160                                  */
 161                                 stage = ce_stage(nce);
 162                                 if (2 <= stage) {
 163                                         int mode = nce->ce_mode;
 164                                         num_compare_stages++;
 165                                         oidcpy(&dpath->parent[stage - 2].oid,
 166                                                &nce->oid);
 167                                         dpath->parent[stage-2].mode = ce_mode_from_stat(nce, mode);
 168                                         dpath->parent[stage-2].status =
 169                                                 DIFF_STATUS_MODIFIED;
 170                                 }
 171
 172                                 /* diff against the proper unmerged stage */
 173                                 if (stage == diff_unmerged_stage)
 174                                         ce = nce;
 175                                 i++;
 176                         }
 177                         /*
 178                          * Compensate for loop update
 179                          */
 180                         i--;
 181
 182                         if (revs->combine_merges && num_compare_stages == 2) {
 183                                 show_combined_diff(dpath, 2, revs);
 184                                 free(dpath);
 185                                 continue;
 186                         }
 187                         FREE_AND_NULL(dpath);
 188
 189                         /*
 190                          * Show the diff for the 'ce' if we found the one
 191                          * from the desired stage.
 192                          */
 193                         pair = diff_unmerge(&revs->diffopt, ce->name);
 194                         if (wt_mode)
 195                                 pair->two->mode = wt_mode;
 196                         if (ce_stage(ce) != diff_unmerged_stage)
 197                                 continue;
 198                 }
 199
 200                 if (ce_uptodate(ce) || ce_skip_worktree(ce))
 201                         continue;
 202
 203                 /*
 204                  * When CE_VALID is set (via "update-index --assume-unchanged"
 205                  * or via adding paths while core.ignorestat is set to true),
 206                  * the user has promised that the working tree file for that
 207                  * path will not be modified.  When CE_FSMONITOR_VALID is true,
 208                  * the fsmonitor knows that the path hasn't been modified since
 209                  * we refreshed the cached stat information.  In either case,
 210                  * we do not have to stat to see if the path has been removed
 211                  * or modified.
 212                  */
 213                 if (ce->ce_flags & (CE_VALID | CE_FSMONITOR_VALID)) {
 214                         changed = 0;
 215                         newmode = ce->ce_mode;
 216                 } else {
 217                         struct stat st;
 218
 219                         changed = check_removed(ce, &st);
 220                         if (changed) {
 221                                 if (changed < 0) {
 222                                         perror(ce->name);
 223                                         continue;
 224                                 }
 225                                 diff_addremove(&revs->diffopt, '-', ce->ce_mode,
 226                                                &ce->oid,
 227                                                !is_null_oid(&ce->oid),
 228                                                ce->name, 0);
 229                                 continue;
 230                         } else if (revs->diffopt.ita_invisible_in_index &&
 231                                    ce_intent_to_add(ce)) {
 232                                 newmode = ce_mode_from_stat(ce, st.st_mode);
 233                                 diff_addremove(&revs->diffopt, '+', newmode,
 234                                                &null_oid, 0, ce->name, 0);
 235                                 continue;
 236                         }
 237
 238                         changed = match_stat_with_submodule(&revs->diffopt, ce, &st,
 239                                                             ce_option, &dirty_submodule);
 240                         newmode = ce_mode_from_stat(ce, st.st_mode);
 241                 }
 242
 243                 if (!changed && !dirty_submodule) {
 244                         ce_mark_uptodate(ce);
 245                         mark_fsmonitor_valid(istate, ce);
 246                         if (!revs->diffopt.flags.find_copies_harder)
 247                                 continue;
 248                 }
 249                 oldmode = ce->ce_mode;
 250                 old_oid = &ce->oid;
 251                 new_oid = changed ? &null_oid : &ce->oid;
 252                 diff_change(&revs->diffopt, oldmode, newmode,
 253                             old_oid, new_oid,
 254                             !is_null_oid(old_oid),
 255                             !is_null_oid(new_oid),
 256                             ce->name, 0, dirty_submodule);
 257
 258         }
 259         diffcore_std(&revs->diffopt);
 260         diff_flush(&revs->diffopt);
 261         trace_performance_since(start, "diff-files");
 262         return 0;
 263 }
 264
 265 /*
 266  * diff-index
 267  */
 268
 269 /* A file entry went away or appeared */
 270 static void diff_index_show_file(struct rev_info *revs,
 271                                  const char *prefix,
 272                                  const struct cache_entry *ce,
 273                                  const struct object_id *oid, int oid_valid,
 274                                  unsigned int mode,
 275                                  unsigned dirty_submodule)
 276 {
 277         diff_addremove(&revs->diffopt, prefix[0], mode,
 278                        oid, oid_valid, ce->name, dirty_submodule);
 279 }
 280
 281 static int get_stat_data(const struct cache_entry *ce,
 282                          const struct object_id **oidp,
 283                          unsigned int *modep,
 284                          int cached, int match_missing,
 285                          unsigned *dirty_submodule, struct diff_options *diffopt)
 286 {
 287         const struct object_id *oid = &ce->oid;
 288         unsigned int mode = ce->ce_mode;
 289
 290         if (!cached && !ce_uptodate(ce)) {
 291                 int changed;
 292                 struct stat st;
 293                 changed = check_removed(ce, &st);
 294                 if (changed < 0)
 295                         return -1;
 296                 else if (changed) {
 297                         if (match_missing) {
 298                                 *oidp = oid;
 299                                 *modep = mode;
 300                                 return 0;
 301                         }
 302                         return -1;
 303                 }
 304                 changed = match_stat_with_submodule(diffopt, ce, &st,
 305                                                     0, dirty_submodule);
 306                 if (changed) {
 307                         mode = ce_mode_from_stat(ce, st.st_mode);
 308                         oid = &null_oid;
 309                 }
 310         }
 311
 312         *oidp = oid;
 313         *modep = mode;
 314         return 0;
 315 }
 316
 317 static void show_new_file(struct rev_info *revs,
 318                           const struct cache_entry *new_file,
 319                           int cached, int match_missing)
 320 {
 321         const struct object_id *oid;
 322         unsigned int mode;
 323         unsigned dirty_submodule = 0;
 324
 325         /*
 326          * New file in the index: it might actually be different in
 327          * the working tree.
 328          */
 329         if (get_stat_data(new_file, &oid, &mode, cached, match_missing,
 330             &dirty_submodule, &revs->diffopt) < 0)
 331                 return;
 332
 333         diff_index_show_file(revs, "+", new_file, oid, !is_null_oid(oid), mode, dirty_submodule);
 334 }
 335
 336 static int show_modified(struct rev_info *revs,
 337                          const struct cache_entry *old_entry,
 338                          const struct cache_entry *new_entry,
 339                          int report_missing,
 340                          int cached, int match_missing)
 341 {
 342         unsigned int mode, oldmode;
 343         const struct object_id *oid;
 344         unsigned dirty_submodule = 0;
 345
 346         if (get_stat_data(new_entry, &oid, &mode, cached, match_missing,
 347                           &dirty_submodule, &revs->diffopt) < 0) {
 348                 if (report_missing)
 349                         diff_index_show_file(revs, "-", old_entry,
 350                                              &old_entry->oid, 1, old_entry->ce_mode,
 351                                              0);
 352                 return -1;
 353         }
 354
 355         if (revs->combine_merges && !cached &&
 356             (!oideq(oid, &old_entry->oid) || !oideq(&old_entry->oid, &new_entry->oid))) {
 357                 struct combine_diff_path *p;
 358                 int pathlen = ce_namelen(new_entry);
 359
 360                 p = xmalloc(combine_diff_path_size(2, pathlen));
 361                 p->path = (char *) &p->parent[2];
 362                 p->next = NULL;
 363                 memcpy(p->path, new_entry->name, pathlen);
 364                 p->path[pathlen] = 0;
 365                 p->mode = mode;
 366                 oidclr(&p->oid);
 367                 memset(p->parent, 0, 2 * sizeof(struct combine_diff_parent));
 368                 p->parent[0].status = DIFF_STATUS_MODIFIED;
 369                 p->parent[0].mode = new_entry->ce_mode;
 370                 oidcpy(&p->parent[0].oid, &new_entry->oid);
 371                 p->parent[1].status = DIFF_STATUS_MODIFIED;
 372                 p->parent[1].mode = old_entry->ce_mode;
 373                 oidcpy(&p->parent[1].oid, &old_entry->oid);
 374                 show_combined_diff(p, 2, revs);
 375                 free(p);
 376                 return 0;
 377         }
 378
 379         oldmode = old_entry->ce_mode;
 380         if (mode == oldmode && oideq(oid, &old_entry->oid) && !dirty_submodule &&
 381             !revs->diffopt.flags.find_copies_harder)
 382                 return 0;
 383
 384         diff_change(&revs->diffopt, oldmode, mode,
 385                     &old_entry->oid, oid, 1, !is_null_oid(oid),
 386                     old_entry->name, 0, dirty_submodule);
 387         return 0;
 388 }
 389
 390 /*
 391  * This gets a mix of an existing index and a tree, one pathname entry
 392  * at a time. The index entry may be a single stage-0 one, but it could
 393  * also be multiple unmerged entries (in which case idx_pos/idx_nr will
 394  * give you the position and number of entries in the index).
 395  */
 396 static void do_oneway_diff(struct unpack_trees_options *o,
 397                            const struct cache_entry *idx,
 398                            const struct cache_entry *tree)
 399 {
 400         struct rev_info *revs = o->unpack_data;
 401         int match_missing, cached;
 402
 403         /*
 404          * i-t-a entries do not actually exist in the index (if we're
 405          * looking at its content)
 406          */
 407         if (o->index_only &&
 408             revs->diffopt.ita_invisible_in_index &&
 409             idx && ce_intent_to_add(idx)) {
 410                 idx = NULL;
 411                 if (!tree)
 412                         return; /* nothing to diff.. */
 413         }
 414
 415         /* if the entry is not checked out, don't examine work tree */
 416         cached = o->index_only ||
 417                 (idx && ((idx->ce_flags & CE_VALID) || ce_skip_worktree(idx)));
 418
 419         match_missing = revs->match_missing;
 420
 421         if (cached && idx && ce_stage(idx)) {
 422                 struct diff_filepair *pair;
 423                 pair = diff_unmerge(&revs->diffopt, idx->name);
 424                 if (tree)
 425                         fill_filespec(pair->one, &tree->oid, 1,
 426                                       tree->ce_mode);
 427                 return;
 428         }
 429
 430         /*
 431          * Something added to the tree?
 432          */
 433         if (!tree) {
 434                 show_new_file(revs, idx, cached, match_missing);
 435                 return;
 436         }
 437
 438         /*
 439          * Something removed from the tree?
 440          */
 441         if (!idx) {
 442                 diff_index_show_file(revs, "-", tree, &tree->oid, 1,
 443                                      tree->ce_mode, 0);
 444                 return;
 445         }
 446
 447         /* Show difference between old and new */
 448         show_modified(revs, tree, idx, 1, cached, match_missing);
 449 }
 450
 451 /*
 452  * The unpack_trees() interface is designed for merging, so
 453  * the different source entries are designed primarily for
 454  * the source trees, with the old index being really mainly
 455  * used for being replaced by the result.
 456  *
 457  * For diffing, the index is more important, and we only have a
 458  * single tree.
 459  *
 460  * We're supposed to advance o->pos to skip what we have already processed.
 461  *
 462  * This wrapper makes it all more readable, and takes care of all
 463  * the fairly complex unpack_trees() semantic requirements, including
 464  * the skipping, the path matching, the type conflict cases etc.
 465  */
 466 static int oneway_diff(const struct cache_entry * const *src,
 467                        struct unpack_trees_options *o)
 468 {
 469         const struct cache_entry *idx = src[0];
 470         const struct cache_entry *tree = src[1];
 471         struct rev_info *revs = o->unpack_data;
 472
 473         /*
 474          * Unpack-trees generates a DF/conflict entry if
 475          * there was a directory in the index and a tree
 476          * in the tree. From a diff standpoint, that's a
 477          * delete of the tree and a create of the file.
 478          */
 479         if (tree == o->df_conflict_entry)
 480                 tree = NULL;
 481
 482         if (ce_path_match(revs->diffopt.repo->index,
 483                           idx ? idx : tree,
 484                           &revs->prune_data, NULL)) {
 485                 do_oneway_diff(o, idx, tree);
 486                 if (diff_can_quit_early(&revs->diffopt)) {
 487                         o->exiting_early = 1;
 488                         return -1;
 489                 }
 490         }
 491
 492         return 0;
 493 }
 494
 495 static int diff_cache(struct rev_info *revs,
 496                       const struct object_id *tree_oid,
 497                       const char *tree_name,
 498                       int cached)
 499 {
 500         struct tree *tree;
 501         struct tree_desc t;
 502         struct unpack_trees_options opts;
 503
 504         tree = parse_tree_indirect(tree_oid);
 505         if (!tree)
 506                 return error("bad tree object %s",
 507                              tree_name ? tree_name : oid_to_hex(tree_oid));
 508         memset(&opts, 0, sizeof(opts));
 509         opts.head_idx = 1;
 510         opts.index_only = cached;
 511         opts.diff_index_cached = (cached &&
 512                                   !revs->diffopt.flags.find_copies_harder);
 513         opts.merge = 1;
 514         opts.fn = oneway_diff;
 515         opts.unpack_data = revs;
 516         opts.src_index = revs->diffopt.repo->index;
 517         opts.dst_index = NULL;
 518         opts.pathspec = &revs->diffopt.pathspec;
 519         opts.pathspec->recursive = 1;
 520
 521         init_tree_desc(&t, tree->buffer, tree->size);
 522         return unpack_trees(1, &t, &opts);
 523 }
 524
 525 void diff_get_merge_base(const struct rev_info *revs, struct object_id *mb)
 526 {
 527         int i;
 528         struct commit *mb_child[2] = {0};
 529         struct commit_list *merge_bases;
 530
 531         for (i = 0; i < revs->pending.nr; i++) {
 532                 struct object *obj = revs->pending.objects[i].item;
 533                 if (obj->flags)
 534                         die(_("--merge-base does not work with ranges"));
 535                 if (obj->type != OBJ_COMMIT)
 536                         die(_("--merge-base only works with commits"));
 537         }
 538
 539         /*
 540          * This check must go after the for loop above because A...B
 541          * ranges produce three pending commits, resulting in a
 542          * misleading error message.
 543          */
 544         if (revs->pending.nr < 1 || revs->pending.nr > 2)
 545                 BUG("unexpected revs->pending.nr: %d", revs->pending.nr);
 546
 547         for (i = 0; i < revs->pending.nr; i++)
 548                 mb_child[i] = lookup_commit_reference(the_repository, &revs->pending.objects[i].item->oid);
 549         if (revs->pending.nr == 1) {
 550                 struct object_id oid;
 551
 552                 if (get_oid("HEAD", &oid))
 553                         die(_("unable to get HEAD"));
 554
 555                 mb_child[1] = lookup_commit_reference(the_repository, &oid);
 556         }
 557
 558         merge_bases = repo_get_merge_bases(the_repository, mb_child[0], mb_child[1]);
 559         if (!merge_bases)
 560                 die(_("no merge base found"));
 561         if (merge_bases->next)
 562                 die(_("multiple merge bases found"));
 563
 564         oidcpy(mb, &merge_bases->item->object.oid);
 565
 566         free_commit_list(merge_bases);
 567 }
 568
 569 int run_diff_index(struct rev_info *revs, unsigned int option)
 570 {
 571         struct object_array_entry *ent;
 572         int cached = !!(option & DIFF_INDEX_CACHED);
 573         int merge_base = !!(option & DIFF_INDEX_MERGE_BASE);
 574         struct object_id oid;
 575         const char *name;
 576         char merge_base_hex[GIT_MAX_HEXSZ + 1];
 577
 578         if (revs->pending.nr != 1)
 579                 BUG("run_diff_index must be passed exactly one tree");
 580
 581         trace_performance_enter();
 582         ent = revs->pending.objects;
 583
 584         if (merge_base) {
 585                 diff_get_merge_base(revs, &oid);
 586                 name = oid_to_hex_r(merge_base_hex, &oid);
 587         } else {
 588                 oidcpy(&oid, &ent->item->oid);
 589                 name = ent->name;
 590         }
 591
 592         if (diff_cache(revs, &oid, name, cached))
 593                 exit(128);
 594
 595         diff_set_mnemonic_prefix(&revs->diffopt, "c/", cached ? "i/" : "w/");
 596         diffcore_fix_diff_index();
 597         diffcore_std(&revs->diffopt);
 598         diff_flush(&revs->diffopt);
 599         trace_performance_leave("diff-index");
 600         return 0;
 601 }
 602
 603 int do_diff_cache(const struct object_id *tree_oid, struct diff_options *opt)
 604 {
 605         struct rev_info revs;
 606
 607         repo_init_revisions(opt->repo, &revs, NULL);
 608         copy_pathspec(&revs.prune_data, &opt->pathspec);
 609         diff_setup_done(&revs.diffopt);
 610         revs.diffopt = *opt;
 611
 612         if (diff_cache(&revs, tree_oid, NULL, 1))
 613                 exit(128);
 614         clear_pathspec(&revs.prune_data);
 615         return 0;
 616 }
 617
 618 int index_differs_from(struct repository *r,
 619                        const char *def, const struct diff_flags *flags,
 620                        int ita_invisible_in_index)
 621 {
 622         struct rev_info rev;
 623         struct setup_revision_opt opt;
 624
 625         repo_init_revisions(r, &rev, NULL);
 626         memset(&opt, 0, sizeof(opt));
 627         opt.def = def;
 628         setup_revisions(0, NULL, &rev, &opt);
 629         rev.diffopt.flags.quick = 1;
 630         rev.diffopt.flags.exit_with_status = 1;
 631         if (flags)
 632                 diff_flags_or(&rev.diffopt.flags, flags);
 633         rev.diffopt.ita_invisible_in_index = ita_invisible_in_index;
 634         run_diff_index(&rev, 1);
 635         object_array_clear(&rev.pending);
 636         return (rev.diffopt.flags.has_changes != 0);
 637 }
 638
 639 static struct strbuf *idiff_prefix_cb(struct diff_options *opt, void *data)
 640 {
 641         return data;
 642 }
 643
 644 void show_interdiff(const struct object_id *oid1, const struct object_id *oid2,
 645                     int indent, struct diff_options *diffopt)
 646 {
 647         struct diff_options opts;
 648         struct strbuf prefix = STRBUF_INIT;
 649
 650         memcpy(&opts, diffopt, sizeof(opts));
 651         opts.output_format = DIFF_FORMAT_PATCH;
 652         opts.output_prefix = idiff_prefix_cb;
 653         strbuf_addchars(&prefix, ' ', indent);
 654         opts.output_prefix_data = &prefix;
 655         diff_setup_done(&opts);
 656
 657         diff_tree_oid(oid1, oid2, "", &opts);
 658         diffcore_std(&opts);
 659         diff_flush(&opts);
 660
 661         strbuf_release(&prefix);
 662 }