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(xstrdup(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 || !strcmp(path, "/dev/null"))
  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         if (prefixcmp(path, "../"))
 233                 return 0;
 234         if (!prefix)
 235                 return 1;
 236         for (i = strlen(prefix); !prefixcmp(path, "../"); ) {
 237                 while (i > 0 && prefix[i - 1] != '/')
 238                         i--;
 239                 if (--i < 0)
 240                         return 1;
 241                 path += 3;
 242         }
 243         return 0;
 244 }
 245
 246 int setup_diff_no_index(struct rev_info *revs,
 247                 int argc, const char ** argv, int nongit, const char *prefix)
 248 {
 249         int i;
 250         for (i = 1; i < argc; i++)
 251                 if (argv[i][0] != '-' || argv[i][1] == '\0')
 252                         break;
 253                 else if (!strcmp(argv[i], "--")) {
 254                         i++;
 255                         break;
 256                 } else if (i < argc - 3 && !strcmp(argv[i], "--no-index")) {
 257                         i = argc - 3;
 258                         revs->diffopt.exit_with_status = 1;
 259                         break;
 260                 }
 261         if (argc != i + 2 || (!is_outside_repo(argv[i + 1], nongit, prefix) &&
 262                                 !is_outside_repo(argv[i], nongit, prefix)))
 263                 return -1;
 264
 265         diff_setup(&revs->diffopt);
 266         for (i = 1; i < argc - 2; )
 267                 if (!strcmp(argv[i], "--no-index"))
 268                         i++;
 269                 else {
 270                         int j = diff_opt_parse(&revs->diffopt,
 271                                         argv + i, argc - i);
 272                         if (!j)
 273                                 die("invalid diff option/value: %s", argv[i]);
 274                         i += j;
 275                 }
 276
 277         if (prefix) {
 278                 int len = strlen(prefix);
 279
 280                 revs->diffopt.paths = xcalloc(2, sizeof(char*));
 281                 for (i = 0; i < 2; i++) {
 282                         const char *p = argv[argc - 2 + i];
 283                         /*
 284                          * stdin should be spelled as '-'; if you have
 285                          * path that is '-', spell it as ./-.
 286                          */
 287                         p = (strcmp(p, "-")
 288                              ? xstrdup(prefix_filename(prefix, len, p))
 289                              : p);
 290                         revs->diffopt.paths[i] = p;
 291                 }
 292         }
 293         else
 294                 revs->diffopt.paths = argv + argc - 2;
 295         revs->diffopt.nr_paths = 2;
 296         revs->max_count = -2;
 297         return 0;
 298 }
 299
 300 int run_diff_files_cmd(struct rev_info *revs, int argc, const char **argv)
 301 {
 302         int silent_on_removed;
 303
 304         if (handle_diff_files_args(revs, argc, argv, &silent_on_removed))
 305                 return -1;
 306
 307         if (revs->max_count == -2) {
 308                 if (revs->diffopt.nr_paths != 2)
 309                         return error("need two files/directories with --no-index");
 310                 if (queue_diff(&revs->diffopt, revs->diffopt.paths[0],
 311                                 revs->diffopt.paths[1]))
 312                         return -1;
 313                 diffcore_std(&revs->diffopt);
 314                 diff_flush(&revs->diffopt);
 315                 /*
 316                  * The return code for --no-index imitates diff(1):
 317                  * 0 = no changes, 1 = changes, else error
 318                  */
 319                 return revs->diffopt.found_changes;
 320         }
 321
 322         if (read_cache() < 0) {
 323                 perror("read_cache");
 324                 return -1;
 325         }
 326         return run_diff_files(revs, silent_on_removed);
 327 }
 328
 329 int run_diff_files(struct rev_info *revs, int silent_on_removed)
 330 {
 331         int entries, i;
 332         int diff_unmerged_stage = revs->max_count;
 333
 334         if (diff_unmerged_stage < 0)
 335                 diff_unmerged_stage = 2;
 336         entries = active_nr;
 337         for (i = 0; i < entries; i++) {
 338                 struct stat st;
 339                 unsigned int oldmode, newmode;
 340                 struct cache_entry *ce = active_cache[i];
 341                 int changed;
 342
 343                 if (revs->diffopt.quiet && revs->diffopt.has_changes)
 344                         break;
 345
 346                 if (!ce_path_match(ce, revs->prune_data))
 347                         continue;
 348
 349                 if (ce_stage(ce)) {
 350                         struct combine_diff_path *dpath;
 351                         int num_compare_stages = 0;
 352                         size_t path_len;
 353
 354                         path_len = ce_namelen(ce);
 355
 356                         dpath = xmalloc(combine_diff_path_size(5, path_len));
 357                         dpath->path = (char *) &(dpath->parent[5]);
 358
 359                         dpath->next = NULL;
 360                         dpath->len = path_len;
 361                         memcpy(dpath->path, ce->name, path_len);
 362                         dpath->path[path_len] = '\0';
 363                         hashclr(dpath->sha1);
 364                         memset(&(dpath->parent[0]), 0,
 365                                sizeof(struct combine_diff_parent)*5);
 366
 367                         if (lstat(ce->name, &st) < 0) {
 368                                 if (errno != ENOENT && errno != ENOTDIR) {
 369                                         perror(ce->name);
 370                                         continue;
 371                                 }
 372                                 if (silent_on_removed)
 373                                         continue;
 374                         }
 375                         else
 376                                 dpath->mode = ntohl(ce_mode_from_stat(ce, st.st_mode));
 377
 378                         while (i < entries) {
 379                                 struct cache_entry *nce = active_cache[i];
 380                                 int stage;
 381
 382                                 if (strcmp(ce->name, nce->name))
 383                                         break;
 384
 385                                 /* Stage #2 (ours) is the first parent,
 386                                  * stage #3 (theirs) is the second.
 387                                  */
 388                                 stage = ce_stage(nce);
 389                                 if (2 <= stage) {
 390                                         int mode = ntohl(nce->ce_mode);
 391                                         num_compare_stages++;
 392                                         hashcpy(dpath->parent[stage-2].sha1, nce->sha1);
 393                                         dpath->parent[stage-2].mode = ntohl(ce_mode_from_stat(nce, mode));
 394                                         dpath->parent[stage-2].status =
 395                                                 DIFF_STATUS_MODIFIED;
 396                                 }
 397
 398                                 /* diff against the proper unmerged stage */
 399                                 if (stage == diff_unmerged_stage)
 400                                         ce = nce;
 401                                 i++;
 402                         }
 403                         /*
 404                          * Compensate for loop update
 405                          */
 406                         i--;
 407
 408                         if (revs->combine_merges && num_compare_stages == 2) {
 409                                 show_combined_diff(dpath, 2,
 410                                                    revs->dense_combined_merges,
 411                                                    revs);
 412                                 free(dpath);
 413                                 continue;
 414                         }
 415                         free(dpath);
 416                         dpath = NULL;
 417
 418                         /*
 419                          * Show the diff for the 'ce' if we found the one
 420                          * from the desired stage.
 421                          */
 422                         diff_unmerge(&revs->diffopt, ce->name, 0, null_sha1);
 423                         if (ce_stage(ce) != diff_unmerged_stage)
 424                                 continue;
 425                 }
 426
 427                 if (lstat(ce->name, &st) < 0) {
 428                         if (errno != ENOENT && errno != ENOTDIR) {
 429                                 perror(ce->name);
 430                                 continue;
 431                         }
 432                         if (silent_on_removed)
 433                                 continue;
 434                         diff_addremove(&revs->diffopt, '-', ntohl(ce->ce_mode),
 435                                        ce->sha1, ce->name, NULL);
 436                         continue;
 437                 }
 438                 changed = ce_match_stat(ce, &st, 0);
 439                 if (!changed && !revs->diffopt.find_copies_harder)
 440                         continue;
 441                 oldmode = ntohl(ce->ce_mode);
 442                 newmode = ntohl(ce_mode_from_stat(ce, st.st_mode));
 443                 diff_change(&revs->diffopt, oldmode, newmode,
 444                             ce->sha1, (changed ? null_sha1 : ce->sha1),
 445                             ce->name, NULL);
 446
 447         }
 448         diffcore_std(&revs->diffopt);
 449         diff_flush(&revs->diffopt);
 450         return 0;
 451 }
 452
 453 /*
 454  * diff-index
 455  */
 456
 457 /* A file entry went away or appeared */
 458 static void diff_index_show_file(struct rev_info *revs,
 459                                  const char *prefix,
 460                                  struct cache_entry *ce,
 461                                  unsigned char *sha1, unsigned int mode)
 462 {
 463         diff_addremove(&revs->diffopt, prefix[0], ntohl(mode),
 464                        sha1, ce->name, NULL);
 465 }
 466
 467 static int get_stat_data(struct cache_entry *ce,
 468                          unsigned char **sha1p,
 469                          unsigned int *modep,
 470                          int cached, int match_missing)
 471 {
 472         unsigned char *sha1 = ce->sha1;
 473         unsigned int mode = ce->ce_mode;
 474
 475         if (!cached) {
 476                 static unsigned char no_sha1[20];
 477                 int changed;
 478                 struct stat st;
 479                 if (lstat(ce->name, &st) < 0) {
 480                         if (errno == ENOENT && match_missing) {
 481                                 *sha1p = sha1;
 482                                 *modep = mode;
 483                                 return 0;
 484                         }
 485                         return -1;
 486                 }
 487                 changed = ce_match_stat(ce, &st, 0);
 488                 if (changed) {
 489                         mode = ce_mode_from_stat(ce, st.st_mode);
 490                         sha1 = no_sha1;
 491                 }
 492         }
 493
 494         *sha1p = sha1;
 495         *modep = mode;
 496         return 0;
 497 }
 498
 499 static void show_new_file(struct rev_info *revs,
 500                           struct cache_entry *new,
 501                           int cached, int match_missing)
 502 {
 503         unsigned char *sha1;
 504         unsigned int mode;
 505
 506         /* New file in the index: it might actually be different in
 507          * the working copy.
 508          */
 509         if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0)
 510                 return;
 511
 512         diff_index_show_file(revs, "+", new, sha1, mode);
 513 }
 514
 515 static int show_modified(struct rev_info *revs,
 516                          struct cache_entry *old,
 517                          struct cache_entry *new,
 518                          int report_missing,
 519                          int cached, int match_missing)
 520 {
 521         unsigned int mode, oldmode;
 522         unsigned char *sha1;
 523
 524         if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0) {
 525                 if (report_missing)
 526                         diff_index_show_file(revs, "-", old,
 527                                              old->sha1, old->ce_mode);
 528                 return -1;
 529         }
 530
 531         if (revs->combine_merges && !cached &&
 532             (hashcmp(sha1, old->sha1) || hashcmp(old->sha1, new->sha1))) {
 533                 struct combine_diff_path *p;
 534                 int pathlen = ce_namelen(new);
 535
 536                 p = xmalloc(combine_diff_path_size(2, pathlen));
 537                 p->path = (char *) &p->parent[2];
 538                 p->next = NULL;
 539                 p->len = pathlen;
 540                 memcpy(p->path, new->name, pathlen);
 541                 p->path[pathlen] = 0;
 542                 p->mode = ntohl(mode);
 543                 hashclr(p->sha1);
 544                 memset(p->parent, 0, 2 * sizeof(struct combine_diff_parent));
 545                 p->parent[0].status = DIFF_STATUS_MODIFIED;
 546                 p->parent[0].mode = ntohl(new->ce_mode);
 547                 hashcpy(p->parent[0].sha1, new->sha1);
 548                 p->parent[1].status = DIFF_STATUS_MODIFIED;
 549                 p->parent[1].mode = ntohl(old->ce_mode);
 550                 hashcpy(p->parent[1].sha1, old->sha1);
 551                 show_combined_diff(p, 2, revs->dense_combined_merges, revs);
 552                 free(p);
 553                 return 0;
 554         }
 555
 556         oldmode = old->ce_mode;
 557         if (mode == oldmode && !hashcmp(sha1, old->sha1) &&
 558             !revs->diffopt.find_copies_harder)
 559                 return 0;
 560
 561         mode = ntohl(mode);
 562         oldmode = ntohl(oldmode);
 563
 564         diff_change(&revs->diffopt, oldmode, mode,
 565                     old->sha1, sha1, old->name, NULL);
 566         return 0;
 567 }
 568
 569 static int diff_cache(struct rev_info *revs,
 570                       struct cache_entry **ac, int entries,
 571                       const char **pathspec,
 572                       int cached, int match_missing)
 573 {
 574         while (entries) {
 575                 struct cache_entry *ce = *ac;
 576                 int same = (entries > 1) && ce_same_name(ce, ac[1]);
 577
 578                 if (revs->diffopt.quiet && revs->diffopt.has_changes)
 579                         break;
 580
 581                 if (!ce_path_match(ce, pathspec))
 582                         goto skip_entry;
 583
 584                 switch (ce_stage(ce)) {
 585                 case 0:
 586                         /* No stage 1 entry? That means it's a new file */
 587                         if (!same) {
 588                                 show_new_file(revs, ce, cached, match_missing);
 589                                 break;
 590                         }
 591                         /* Show difference between old and new */
 592                         show_modified(revs, ac[1], ce, 1,
 593                                       cached, match_missing);
 594                         break;
 595                 case 1:
 596                         /* No stage 3 (merge) entry?
 597                          * That means it's been deleted.
 598                          */
 599                         if (!same) {
 600                                 diff_index_show_file(revs, "-", ce,
 601                                                      ce->sha1, ce->ce_mode);
 602                                 break;
 603                         }
 604                         /* We come here with ce pointing at stage 1
 605                          * (original tree) and ac[1] pointing at stage
 606                          * 3 (unmerged).  show-modified with
 607                          * report-missing set to false does not say the
 608                          * file is deleted but reports true if work
 609                          * tree does not have it, in which case we
 610                          * fall through to report the unmerged state.
 611                          * Otherwise, we show the differences between
 612                          * the original tree and the work tree.
 613                          */
 614                         if (!cached &&
 615                             !show_modified(revs, ce, ac[1], 0,
 616                                            cached, match_missing))
 617                                 break;
 618                         diff_unmerge(&revs->diffopt, ce->name,
 619                                      ntohl(ce->ce_mode), ce->sha1);
 620                         break;
 621                 case 3:
 622                         diff_unmerge(&revs->diffopt, ce->name,
 623                                      0, null_sha1);
 624                         break;
 625
 626                 default:
 627                         die("impossible cache entry stage");
 628                 }
 629
 630 skip_entry:
 631                 /*
 632                  * Ignore all the different stages for this file,
 633                  * we've handled the relevant cases now.
 634                  */
 635                 do {
 636                         ac++;
 637                         entries--;
 638                 } while (entries && ce_same_name(ce, ac[0]));
 639         }
 640         return 0;
 641 }
 642
 643 /*
 644  * This turns all merge entries into "stage 3". That guarantees that
 645  * when we read in the new tree (into "stage 1"), we won't lose sight
 646  * of the fact that we had unmerged entries.
 647  */
 648 static void mark_merge_entries(void)
 649 {
 650         int i;
 651         for (i = 0; i < active_nr; i++) {
 652                 struct cache_entry *ce = active_cache[i];
 653                 if (!ce_stage(ce))
 654                         continue;
 655                 ce->ce_flags |= htons(CE_STAGEMASK);
 656         }
 657 }
 658
 659 int run_diff_index(struct rev_info *revs, int cached)
 660 {
 661         int ret;
 662         struct object *ent;
 663         struct tree *tree;
 664         const char *tree_name;
 665         int match_missing = 0;
 666
 667         /*
 668          * Backward compatibility wart - "diff-index -m" does
 669          * not mean "do not ignore merges", but totally different.
 670          */
 671         if (!revs->ignore_merges)
 672                 match_missing = 1;
 673
 674         mark_merge_entries();
 675
 676         ent = revs->pending.objects[0].item;
 677         tree_name = revs->pending.objects[0].name;
 678         tree = parse_tree_indirect(ent->sha1);
 679         if (!tree)
 680                 return error("bad tree object %s", tree_name);
 681         if (read_tree(tree, 1, revs->prune_data))
 682                 return error("unable to read tree object %s", tree_name);
 683         ret = diff_cache(revs, active_cache, active_nr, revs->prune_data,
 684                          cached, match_missing);
 685         diffcore_std(&revs->diffopt);
 686         diff_flush(&revs->diffopt);
 687         return ret;
 688 }
 689
 690 int do_diff_cache(const unsigned char *tree_sha1, struct diff_options *opt)
 691 {
 692         struct tree *tree;
 693         struct rev_info revs;
 694         int i;
 695         struct cache_entry **dst;
 696         struct cache_entry *last = NULL;
 697
 698         /*
 699          * This is used by git-blame to run diff-cache internally;
 700          * it potentially needs to repeatedly run this, so we will
 701          * start by removing the higher order entries the last round
 702          * left behind.
 703          */
 704         dst = active_cache;
 705         for (i = 0; i < active_nr; i++) {
 706                 struct cache_entry *ce = active_cache[i];
 707                 if (ce_stage(ce)) {
 708                         if (last && !strcmp(ce->name, last->name))
 709                                 continue;
 710                         cache_tree_invalidate_path(active_cache_tree,
 711                                                    ce->name);
 712                         last = ce;
 713                         ce->ce_mode = 0;
 714                         ce->ce_flags &= ~htons(CE_STAGEMASK);
 715                 }
 716                 *dst++ = ce;
 717         }
 718         active_nr = dst - active_cache;
 719
 720         init_revisions(&revs, NULL);
 721         revs.prune_data = opt->paths;
 722         tree = parse_tree_indirect(tree_sha1);
 723         if (!tree)
 724                 die("bad tree object %s", sha1_to_hex(tree_sha1));
 725         if (read_tree(tree, 1, opt->paths))
 726                 return error("unable to read tree %s", sha1_to_hex(tree_sha1));
 727         return diff_cache(&revs, active_cache, active_nr, revs.prune_data,
 728                           1, 0);
 729 }