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 "path-list.h"
  12
  13 /*
  14  * diff-files
  15  */
  16
  17 static int read_directory(const char *path, struct path_list *list)
  18 {
  19         DIR *dir;
  20         struct dirent *e;
  21
  22         if (!(dir = opendir(path)))
  23                 return error("Could not open directory %s", path);
  24
  25         while ((e = readdir(dir)))
  26                 if (strcmp(".", e->d_name) && strcmp("..", e->d_name))
  27                         path_list_insert(e->d_name, list);
  28
  29         closedir(dir);
  30         return 0;
  31 }
  32
  33 static int get_mode(const char *path, int *mode)
  34 {
  35         struct stat st;
  36
  37         if (!path || is_dev_null(path))
  38                 *mode = 0;
  39         else if (!strcmp(path, "-"))
  40                 *mode = ntohl(create_ce_mode(0666));
  41         else if (stat(path, &st))
  42                 return error("Could not access '%s'", path);
  43         else
  44                 *mode = st.st_mode;
  45         return 0;
  46 }
  47
  48 static int queue_diff(struct diff_options *o,
  49                 const char *name1, const char *name2)
  50 {
  51         int mode1 = 0, mode2 = 0;
  52
  53         if (get_mode(name1, &mode1) || get_mode(name2, &mode2))
  54                 return -1;
  55
  56         if (mode1 && mode2 && S_ISDIR(mode1) != S_ISDIR(mode2))
  57                 return error("file/directory conflict: %s, %s", name1, name2);
  58
  59         if (S_ISDIR(mode1) || S_ISDIR(mode2)) {
  60                 char buffer1[PATH_MAX], buffer2[PATH_MAX];
  61                 struct path_list p1 = {NULL, 0, 0, 1}, p2 = {NULL, 0, 0, 1};
  62                 int len1 = 0, len2 = 0, i1, i2, ret = 0;
  63
  64                 if (name1 && read_directory(name1, &p1))
  65                         return -1;
  66                 if (name2 && read_directory(name2, &p2)) {
  67                         path_list_clear(&p1, 0);
  68                         return -1;
  69                 }
  70
  71                 if (name1) {
  72                         len1 = strlen(name1);
  73                         if (len1 > 0 && name1[len1 - 1] == '/')
  74                                 len1--;
  75                         memcpy(buffer1, name1, len1);
  76                         buffer1[len1++] = '/';
  77                 }
  78
  79                 if (name2) {
  80                         len2 = strlen(name2);
  81                         if (len2 > 0 && name2[len2 - 1] == '/')
  82                                 len2--;
  83                         memcpy(buffer2, name2, len2);
  84                         buffer2[len2++] = '/';
  85                 }
  86
  87                 for (i1 = i2 = 0; !ret && (i1 < p1.nr || i2 < p2.nr); ) {
  88                         const char *n1, *n2;
  89                         int comp;
  90
  91                         if (i1 == p1.nr)
  92                                 comp = 1;
  93                         else if (i2 == p2.nr)
  94                                 comp = -1;
  95                         else
  96                                 comp = strcmp(p1.items[i1].path,
  97                                         p2.items[i2].path);
  98
  99                         if (comp > 0)
 100                                 n1 = NULL;
 101                         else {
 102                                 n1 = buffer1;
 103                                 strncpy(buffer1 + len1, p1.items[i1++].path,
 104                                                 PATH_MAX - len1);
 105                         }
 106
 107                         if (comp < 0)
 108                                 n2 = NULL;
 109                         else {
 110                                 n2 = buffer2;
 111                                 strncpy(buffer2 + len2, p2.items[i2++].path,
 112                                                 PATH_MAX - len2);
 113                         }
 114
 115                         ret = queue_diff(o, n1, n2);
 116                 }
 117                 path_list_clear(&p1, 0);
 118                 path_list_clear(&p2, 0);
 119
 120                 return ret;
 121         } else {
 122                 struct diff_filespec *d1, *d2;
 123
 124                 if (o->reverse_diff) {
 125                         unsigned tmp;
 126                         const char *tmp_c;
 127                         tmp = mode1; mode1 = mode2; mode2 = tmp;
 128                         tmp_c = name1; name1 = name2; name2 = tmp_c;
 129                 }
 130
 131                 if (!name1)
 132                         name1 = "/dev/null";
 133                 if (!name2)
 134                         name2 = "/dev/null";
 135                 d1 = alloc_filespec(name1);
 136                 d2 = alloc_filespec(name2);
 137                 fill_filespec(d1, null_sha1, mode1);
 138                 fill_filespec(d2, null_sha1, mode2);
 139
 140                 diff_queue(&diff_queued_diff, d1, d2);
 141                 return 0;
 142         }
 143 }
 144
 145 /*
 146  * Does the path name a blob in the working tree, or a directory
 147  * in the working tree?
 148  */
 149 static int is_in_index(const char *path)
 150 {
 151         int len, pos;
 152         struct cache_entry *ce;
 153
 154         len = strlen(path);
 155         while (path[len-1] == '/')
 156                 len--;
 157         if (!len)
 158                 return 1; /* "." */
 159         pos = cache_name_pos(path, len);
 160         if (0 <= pos)
 161                 return 1;
 162         pos = -1 - pos;
 163         while (pos < active_nr) {
 164                 ce = active_cache[pos++];
 165                 if (ce_namelen(ce) <= len ||
 166                     strncmp(ce->name, path, len) ||
 167                     (ce->name[len] > '/'))
 168                         break; /* path cannot be a prefix */
 169                 if (ce->name[len] == '/')
 170                         return 1;
 171         }
 172         return 0;
 173 }
 174
 175 static int handle_diff_files_args(struct rev_info *revs,
 176                 int argc, const char **argv, int *silent)
 177 {
 178         *silent = 0;
 179
 180         /* revs->max_count == -2 means --no-index */
 181         while (1 < argc && argv[1][0] == '-') {
 182                 if (!strcmp(argv[1], "--base"))
 183                         revs->max_count = 1;
 184                 else if (!strcmp(argv[1], "--ours"))
 185                         revs->max_count = 2;
 186                 else if (!strcmp(argv[1], "--theirs"))
 187                         revs->max_count = 3;
 188                 else if (!strcmp(argv[1], "-n") ||
 189                                 !strcmp(argv[1], "--no-index")) {
 190                         revs->max_count = -2;
 191                         revs->diffopt.exit_with_status = 1;
 192                 }
 193                 else if (!strcmp(argv[1], "-q"))
 194                         *silent = 1;
 195                 else
 196                         return error("invalid option: %s", argv[1]);
 197                 argv++; argc--;
 198         }
 199
 200         if (revs->max_count == -1 && revs->diffopt.nr_paths == 2) {
 201                 /*
 202                  * If two files are specified, and at least one is untracked,
 203                  * default to no-index.
 204                  */
 205                 read_cache();
 206                 if (!is_in_index(revs->diffopt.paths[0]) ||
 207                                         !is_in_index(revs->diffopt.paths[1]))
 208                         revs->max_count = -2;
 209         }
 210
 211         /*
 212          * Make sure there are NO revision (i.e. pending object) parameter,
 213          * rev.max_count is reasonable (0 <= n <= 3),
 214          * there is no other revision filtering parameters.
 215          */
 216         if (revs->pending.nr || revs->max_count > 3 ||
 217             revs->min_age != -1 || revs->max_age != -1)
 218                 return error("no revision allowed with diff-files");
 219
 220         if (revs->max_count == -1 &&
 221             (revs->diffopt.output_format & DIFF_FORMAT_PATCH))
 222                 revs->combine_merges = revs->dense_combined_merges = 1;
 223
 224         return 0;
 225 }
 226
 227 static int is_outside_repo(const char *path, int nongit, const char *prefix)
 228 {
 229         int i;
 230         if (nongit || !strcmp(path, "-") || path[0] == '/')
 231                 return 1;
 232 #ifdef __MINGW32__
 233         if (!strcmp(path, "nul"))
 234                 return 1;
 235 #endif
 236         if (prefixcmp(path, "../"))
 237                 return 0;
 238         if (!prefix)
 239                 return 1;
 240         for (i = strlen(prefix); !prefixcmp(path, "../"); ) {
 241                 while (i > 0 && prefix[i - 1] != '/')
 242                         i--;
 243                 if (--i < 0)
 244                         return 1;
 245                 path += 3;
 246         }
 247         return 0;
 248 }
 249
 250 int setup_diff_no_index(struct rev_info *revs,
 251                 int argc, const char ** argv, int nongit, const char *prefix)
 252 {
 253         int i;
 254         for (i = 1; i < argc; i++)
 255                 if (argv[i][0] != '-' || argv[i][1] == '\0')
 256                         break;
 257                 else if (!strcmp(argv[i], "--")) {
 258                         i++;
 259                         break;
 260                 } else if (i < argc - 3 && !strcmp(argv[i], "--no-index")) {
 261                         i = argc - 3;
 262                         revs->diffopt.exit_with_status = 1;
 263                         break;
 264                 }
 265         if (argc != i + 2 || (!is_outside_repo(argv[i + 1], nongit, prefix) &&
 266                                 !is_outside_repo(argv[i], nongit, prefix)))
 267                 return -1;
 268
 269         diff_setup(&revs->diffopt);
 270         for (i = 1; i < argc - 2; )
 271                 if (!strcmp(argv[i], "--no-index"))
 272                         i++;
 273                 else {
 274                         int j = diff_opt_parse(&revs->diffopt,
 275                                         argv + i, argc - i);
 276                         if (!j)
 277                                 die("invalid diff option/value: %s", argv[i]);
 278                         i += j;
 279                 }
 280
 281         if (prefix) {
 282                 int len = strlen(prefix);
 283
 284                 revs->diffopt.paths = xcalloc(2, sizeof(char*));
 285                 for (i = 0; i < 2; i++) {
 286                         const char *p = argv[argc - 2 + i];
 287                         /*
 288                          * stdin should be spelled as '-'; if you have
 289                          * path that is '-', spell it as ./-.
 290                          */
 291                         p = (strcmp(p, "-")
 292                              ? xstrdup(prefix_filename(prefix, len, p))
 293                              : p);
 294                         revs->diffopt.paths[i] = p;
 295                 }
 296         }
 297         else
 298                 revs->diffopt.paths = argv + argc - 2;
 299         revs->diffopt.nr_paths = 2;
 300         revs->max_count = -2;
 301         return 0;
 302 }
 303
 304 int run_diff_files_cmd(struct rev_info *revs, int argc, const char **argv)
 305 {
 306         int silent_on_removed;
 307
 308         if (handle_diff_files_args(revs, argc, argv, &silent_on_removed))
 309                 return -1;
 310
 311         if (revs->max_count == -2) {
 312                 if (revs->diffopt.nr_paths != 2)
 313                         return error("need two files/directories with --no-index");
 314                 if (queue_diff(&revs->diffopt, revs->diffopt.paths[0],
 315                                 revs->diffopt.paths[1]))
 316                         return -1;
 317                 diffcore_std(&revs->diffopt);
 318                 diff_flush(&revs->diffopt);
 319                 /*
 320                  * The return code for --no-index imitates diff(1):
 321                  * 0 = no changes, 1 = changes, else error
 322                  */
 323                 return revs->diffopt.found_changes;
 324         }
 325
 326         if (read_cache() < 0) {
 327                 perror("read_cache");
 328                 return -1;
 329         }
 330         return run_diff_files(revs, silent_on_removed);
 331 }
 332
 333 int run_diff_files(struct rev_info *revs, int silent_on_removed)
 334 {
 335         int entries, i;
 336         int diff_unmerged_stage = revs->max_count;
 337
 338         if (diff_unmerged_stage < 0)
 339                 diff_unmerged_stage = 2;
 340         entries = active_nr;
 341         for (i = 0; i < entries; i++) {
 342                 struct stat st;
 343                 unsigned int oldmode, newmode;
 344                 struct cache_entry *ce = active_cache[i];
 345                 int changed;
 346
 347                 if (revs->diffopt.quiet && revs->diffopt.has_changes)
 348                         break;
 349
 350                 if (!ce_path_match(ce, revs->prune_data))
 351                         continue;
 352
 353                 if (ce_stage(ce)) {
 354                         struct combine_diff_path *dpath;
 355                         int num_compare_stages = 0;
 356                         size_t path_len;
 357
 358                         path_len = ce_namelen(ce);
 359
 360                         dpath = xmalloc(combine_diff_path_size(5, path_len));
 361                         dpath->path = (char *) &(dpath->parent[5]);
 362
 363                         dpath->next = NULL;
 364                         dpath->len = path_len;
 365                         memcpy(dpath->path, ce->name, path_len);
 366                         dpath->path[path_len] = '\0';
 367                         hashclr(dpath->sha1);
 368                         memset(&(dpath->parent[0]), 0,
 369                                sizeof(struct combine_diff_parent)*5);
 370
 371                         if (lstat(ce->name, &st) < 0) {
 372                                 if (errno != ENOENT && errno != ENOTDIR) {
 373                                         perror(ce->name);
 374                                         continue;
 375                                 }
 376                                 if (silent_on_removed)
 377                                         continue;
 378                         }
 379                         else
 380                                 dpath->mode = ntohl(ce_mode_from_stat(ce, st.st_mode));
 381
 382                         while (i < entries) {
 383                                 struct cache_entry *nce = active_cache[i];
 384                                 int stage;
 385
 386                                 if (strcmp(ce->name, nce->name))
 387                                         break;
 388
 389                                 /* Stage #2 (ours) is the first parent,
 390                                  * stage #3 (theirs) is the second.
 391                                  */
 392                                 stage = ce_stage(nce);
 393                                 if (2 <= stage) {
 394                                         int mode = ntohl(nce->ce_mode);
 395                                         num_compare_stages++;
 396                                         hashcpy(dpath->parent[stage-2].sha1, nce->sha1);
 397                                         dpath->parent[stage-2].mode = ntohl(ce_mode_from_stat(nce, mode));
 398                                         dpath->parent[stage-2].status =
 399                                                 DIFF_STATUS_MODIFIED;
 400                                 }
 401
 402                                 /* diff against the proper unmerged stage */
 403                                 if (stage == diff_unmerged_stage)
 404                                         ce = nce;
 405                                 i++;
 406                         }
 407                         /*
 408                          * Compensate for loop update
 409                          */
 410                         i--;
 411
 412                         if (revs->combine_merges && num_compare_stages == 2) {
 413                                 show_combined_diff(dpath, 2,
 414                                                    revs->dense_combined_merges,
 415                                                    revs);
 416                                 free(dpath);
 417                                 continue;
 418                         }
 419                         free(dpath);
 420                         dpath = NULL;
 421
 422                         /*
 423                          * Show the diff for the 'ce' if we found the one
 424                          * from the desired stage.
 425                          */
 426                         diff_unmerge(&revs->diffopt, ce->name, 0, null_sha1);
 427                         if (ce_stage(ce) != diff_unmerged_stage)
 428                                 continue;
 429                 }
 430
 431                 if (lstat(ce->name, &st) < 0) {
 432                         if (errno != ENOENT && errno != ENOTDIR) {
 433                                 perror(ce->name);
 434                                 continue;
 435                         }
 436                         if (silent_on_removed)
 437                                 continue;
 438                         diff_addremove(&revs->diffopt, '-', ntohl(ce->ce_mode),
 439                                        ce->sha1, ce->name, NULL);
 440                         continue;
 441                 }
 442                 changed = ce_match_stat(ce, &st, 0);
 443                 if (!changed && !revs->diffopt.find_copies_harder)
 444                         continue;
 445                 oldmode = ntohl(ce->ce_mode);
 446                 newmode = ntohl(ce_mode_from_stat(ce, st.st_mode));
 447                 diff_change(&revs->diffopt, oldmode, newmode,
 448                             ce->sha1, (changed ? null_sha1 : ce->sha1),
 449                             ce->name, NULL);
 450
 451         }
 452         diffcore_std(&revs->diffopt);
 453         diff_flush(&revs->diffopt);
 454         return 0;
 455 }
 456
 457 /*
 458  * diff-index
 459  */
 460
 461 /* A file entry went away or appeared */
 462 static void diff_index_show_file(struct rev_info *revs,
 463                                  const char *prefix,
 464                                  struct cache_entry *ce,
 465                                  unsigned char *sha1, unsigned int mode)
 466 {
 467         diff_addremove(&revs->diffopt, prefix[0], ntohl(mode),
 468                        sha1, ce->name, NULL);
 469 }
 470
 471 static int get_stat_data(struct cache_entry *ce,
 472                          unsigned char **sha1p,
 473                          unsigned int *modep,
 474                          int cached, int match_missing)
 475 {
 476         unsigned char *sha1 = ce->sha1;
 477         unsigned int mode = ce->ce_mode;
 478
 479         if (!cached) {
 480                 static unsigned char no_sha1[20];
 481                 int changed;
 482                 struct stat st;
 483                 if (lstat(ce->name, &st) < 0) {
 484                         if (errno == ENOENT && match_missing) {
 485                                 *sha1p = sha1;
 486                                 *modep = mode;
 487                                 return 0;
 488                         }
 489                         return -1;
 490                 }
 491                 changed = ce_match_stat(ce, &st, 0);
 492                 if (changed) {
 493                         mode = ce_mode_from_stat(ce, st.st_mode);
 494                         sha1 = no_sha1;
 495                 }
 496         }
 497
 498         *sha1p = sha1;
 499         *modep = mode;
 500         return 0;
 501 }
 502
 503 static void show_new_file(struct rev_info *revs,
 504                           struct cache_entry *new,
 505                           int cached, int match_missing)
 506 {
 507         unsigned char *sha1;
 508         unsigned int mode;
 509
 510         /* New file in the index: it might actually be different in
 511          * the working copy.
 512          */
 513         if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0)
 514                 return;
 515
 516         diff_index_show_file(revs, "+", new, sha1, mode);
 517 }
 518
 519 static int show_modified(struct rev_info *revs,
 520                          struct cache_entry *old,
 521                          struct cache_entry *new,
 522                          int report_missing,
 523                          int cached, int match_missing)
 524 {
 525         unsigned int mode, oldmode;
 526         unsigned char *sha1;
 527
 528         if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0) {
 529                 if (report_missing)
 530                         diff_index_show_file(revs, "-", old,
 531                                              old->sha1, old->ce_mode);
 532                 return -1;
 533         }
 534
 535         if (revs->combine_merges && !cached &&
 536             (hashcmp(sha1, old->sha1) || hashcmp(old->sha1, new->sha1))) {
 537                 struct combine_diff_path *p;
 538                 int pathlen = ce_namelen(new);
 539
 540                 p = xmalloc(combine_diff_path_size(2, pathlen));
 541                 p->path = (char *) &p->parent[2];
 542                 p->next = NULL;
 543                 p->len = pathlen;
 544                 memcpy(p->path, new->name, pathlen);
 545                 p->path[pathlen] = 0;
 546                 p->mode = ntohl(mode);
 547                 hashclr(p->sha1);
 548                 memset(p->parent, 0, 2 * sizeof(struct combine_diff_parent));
 549                 p->parent[0].status = DIFF_STATUS_MODIFIED;
 550                 p->parent[0].mode = ntohl(new->ce_mode);
 551                 hashcpy(p->parent[0].sha1, new->sha1);
 552                 p->parent[1].status = DIFF_STATUS_MODIFIED;
 553                 p->parent[1].mode = ntohl(old->ce_mode);
 554                 hashcpy(p->parent[1].sha1, old->sha1);
 555                 show_combined_diff(p, 2, revs->dense_combined_merges, revs);
 556                 free(p);
 557                 return 0;
 558         }
 559
 560         oldmode = old->ce_mode;
 561         if (mode == oldmode && !hashcmp(sha1, old->sha1) &&
 562             !revs->diffopt.find_copies_harder)
 563                 return 0;
 564
 565         mode = ntohl(mode);
 566         oldmode = ntohl(oldmode);
 567
 568         diff_change(&revs->diffopt, oldmode, mode,
 569                     old->sha1, sha1, old->name, NULL);
 570         return 0;
 571 }
 572
 573 static int diff_cache(struct rev_info *revs,
 574                       struct cache_entry **ac, int entries,
 575                       const char **pathspec,
 576                       int cached, int match_missing)
 577 {
 578         while (entries) {
 579                 struct cache_entry *ce = *ac;
 580                 int same = (entries > 1) && ce_same_name(ce, ac[1]);
 581
 582                 if (revs->diffopt.quiet && revs->diffopt.has_changes)
 583                         break;
 584
 585                 if (!ce_path_match(ce, pathspec))
 586                         goto skip_entry;
 587
 588                 switch (ce_stage(ce)) {
 589                 case 0:
 590                         /* No stage 1 entry? That means it's a new file */
 591                         if (!same) {
 592                                 show_new_file(revs, ce, cached, match_missing);
 593                                 break;
 594                         }
 595                         /* Show difference between old and new */
 596                         show_modified(revs, ac[1], ce, 1,
 597                                       cached, match_missing);
 598                         break;
 599                 case 1:
 600                         /* No stage 3 (merge) entry?
 601                          * That means it's been deleted.
 602                          */
 603                         if (!same) {
 604                                 diff_index_show_file(revs, "-", ce,
 605                                                      ce->sha1, ce->ce_mode);
 606                                 break;
 607                         }
 608                         /* We come here with ce pointing at stage 1
 609                          * (original tree) and ac[1] pointing at stage
 610                          * 3 (unmerged).  show-modified with
 611                          * report-missing set to false does not say the
 612                          * file is deleted but reports true if work
 613                          * tree does not have it, in which case we
 614                          * fall through to report the unmerged state.
 615                          * Otherwise, we show the differences between
 616                          * the original tree and the work tree.
 617                          */
 618                         if (!cached &&
 619                             !show_modified(revs, ce, ac[1], 0,
 620                                            cached, match_missing))
 621                                 break;
 622                         diff_unmerge(&revs->diffopt, ce->name,
 623                                      ntohl(ce->ce_mode), ce->sha1);
 624                         break;
 625                 case 3:
 626                         diff_unmerge(&revs->diffopt, ce->name,
 627                                      0, null_sha1);
 628                         break;
 629
 630                 default:
 631                         die("impossible cache entry stage");
 632                 }
 633
 634 skip_entry:
 635                 /*
 636                  * Ignore all the different stages for this file,
 637                  * we've handled the relevant cases now.
 638                  */
 639                 do {
 640                         ac++;
 641                         entries--;
 642                 } while (entries && ce_same_name(ce, ac[0]));
 643         }
 644         return 0;
 645 }
 646
 647 /*
 648  * This turns all merge entries into "stage 3". That guarantees that
 649  * when we read in the new tree (into "stage 1"), we won't lose sight
 650  * of the fact that we had unmerged entries.
 651  */
 652 static void mark_merge_entries(void)
 653 {
 654         int i;
 655         for (i = 0; i < active_nr; i++) {
 656                 struct cache_entry *ce = active_cache[i];
 657                 if (!ce_stage(ce))
 658                         continue;
 659                 ce->ce_flags |= htons(CE_STAGEMASK);
 660         }
 661 }
 662
 663 int run_diff_index(struct rev_info *revs, int cached)
 664 {
 665         int ret;
 666         struct object *ent;
 667         struct tree *tree;
 668         const char *tree_name;
 669         int match_missing = 0;
 670
 671         /*
 672          * Backward compatibility wart - "diff-index -m" does
 673          * not mean "do not ignore merges", but totally different.
 674          */
 675         if (!revs->ignore_merges)
 676                 match_missing = 1;
 677
 678         mark_merge_entries();
 679
 680         ent = revs->pending.objects[0].item;
 681         tree_name = revs->pending.objects[0].name;
 682         tree = parse_tree_indirect(ent->sha1);
 683         if (!tree)
 684                 return error("bad tree object %s", tree_name);
 685         if (read_tree(tree, 1, revs->prune_data))
 686                 return error("unable to read tree object %s", tree_name);
 687         ret = diff_cache(revs, active_cache, active_nr, revs->prune_data,
 688                          cached, match_missing);
 689         diffcore_std(&revs->diffopt);
 690         diff_flush(&revs->diffopt);
 691         return ret;
 692 }
 693
 694 int do_diff_cache(const unsigned char *tree_sha1, struct diff_options *opt)
 695 {
 696         struct tree *tree;
 697         struct rev_info revs;
 698         int i;
 699         struct cache_entry **dst;
 700         struct cache_entry *last = NULL;
 701
 702         /*
 703          * This is used by git-blame to run diff-cache internally;
 704          * it potentially needs to repeatedly run this, so we will
 705          * start by removing the higher order entries the last round
 706          * left behind.
 707          */
 708         dst = active_cache;
 709         for (i = 0; i < active_nr; i++) {
 710                 struct cache_entry *ce = active_cache[i];
 711                 if (ce_stage(ce)) {
 712                         if (last && !strcmp(ce->name, last->name))
 713                                 continue;
 714                         cache_tree_invalidate_path(active_cache_tree,
 715                                                    ce->name);
 716                         last = ce;
 717                         ce->ce_mode = 0;
 718                         ce->ce_flags &= ~htons(CE_STAGEMASK);
 719                 }
 720                 *dst++ = ce;
 721         }
 722         active_nr = dst - active_cache;
 723
 724         init_revisions(&revs, NULL);
 725         revs.prune_data = opt->paths;
 726         tree = parse_tree_indirect(tree_sha1);
 727         if (!tree)
 728                 die("bad tree object %s", sha1_to_hex(tree_sha1));
 729         if (read_tree(tree, 1, opt->paths))
 730                 return error("unable to read tree %s", sha1_to_hex(tree_sha1));
 731         return diff_cache(&revs, active_cache, active_nr, revs.prune_data,
 732                           1, 0);
 733 }