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 #include "unpack-trees.h"
  13
  14 /*
  15  * diff-files
  16  */
  17
  18 static int read_directory(const char *path, struct path_list *list)
  19 {
  20         DIR *dir;
  21         struct dirent *e;
  22
  23         if (!(dir = opendir(path)))
  24                 return error("Could not open directory %s", path);
  25
  26         while ((e = readdir(dir)))
  27                 if (strcmp(".", e->d_name) && strcmp("..", e->d_name))
  28                         path_list_insert(e->d_name, list);
  29
  30         closedir(dir);
  31         return 0;
  32 }
  33
  34 static int get_mode(const char *path, int *mode)
  35 {
  36         struct stat st;
  37
  38         if (!path || !strcmp(path, "/dev/null"))
  39                 *mode = 0;
  40         else if (!strcmp(path, "-"))
  41                 *mode = create_ce_mode(0666);
  42         else if (stat(path, &st))
  43                 return error("Could not access '%s'", path);
  44         else
  45                 *mode = st.st_mode;
  46         return 0;
  47 }
  48
  49 static int queue_diff(struct diff_options *o,
  50                 const char *name1, const char *name2)
  51 {
  52         int mode1 = 0, mode2 = 0;
  53
  54         if (get_mode(name1, &mode1) || get_mode(name2, &mode2))
  55                 return -1;
  56
  57         if (mode1 && mode2 && S_ISDIR(mode1) != S_ISDIR(mode2))
  58                 return error("file/directory conflict: %s, %s", name1, name2);
  59
  60         if (S_ISDIR(mode1) || S_ISDIR(mode2)) {
  61                 char buffer1[PATH_MAX], buffer2[PATH_MAX];
  62                 struct path_list p1 = {NULL, 0, 0, 1}, p2 = {NULL, 0, 0, 1};
  63                 int len1 = 0, len2 = 0, i1, i2, ret = 0;
  64
  65                 if (name1 && read_directory(name1, &p1))
  66                         return -1;
  67                 if (name2 && read_directory(name2, &p2)) {
  68                         path_list_clear(&p1, 0);
  69                         return -1;
  70                 }
  71
  72                 if (name1) {
  73                         len1 = strlen(name1);
  74                         if (len1 > 0 && name1[len1 - 1] == '/')
  75                                 len1--;
  76                         memcpy(buffer1, name1, len1);
  77                         buffer1[len1++] = '/';
  78                 }
  79
  80                 if (name2) {
  81                         len2 = strlen(name2);
  82                         if (len2 > 0 && name2[len2 - 1] == '/')
  83                                 len2--;
  84                         memcpy(buffer2, name2, len2);
  85                         buffer2[len2++] = '/';
  86                 }
  87
  88                 for (i1 = i2 = 0; !ret && (i1 < p1.nr || i2 < p2.nr); ) {
  89                         const char *n1, *n2;
  90                         int comp;
  91
  92                         if (i1 == p1.nr)
  93                                 comp = 1;
  94                         else if (i2 == p2.nr)
  95                                 comp = -1;
  96                         else
  97                                 comp = strcmp(p1.items[i1].path,
  98                                         p2.items[i2].path);
  99
 100                         if (comp > 0)
 101                                 n1 = NULL;
 102                         else {
 103                                 n1 = buffer1;
 104                                 strncpy(buffer1 + len1, p1.items[i1++].path,
 105                                                 PATH_MAX - len1);
 106                         }
 107
 108                         if (comp < 0)
 109                                 n2 = NULL;
 110                         else {
 111                                 n2 = buffer2;
 112                                 strncpy(buffer2 + len2, p2.items[i2++].path,
 113                                                 PATH_MAX - len2);
 114                         }
 115
 116                         ret = queue_diff(o, n1, n2);
 117                 }
 118                 path_list_clear(&p1, 0);
 119                 path_list_clear(&p2, 0);
 120
 121                 return ret;
 122         } else {
 123                 struct diff_filespec *d1, *d2;
 124
 125                 if (DIFF_OPT_TST(o, REVERSE_DIFF)) {
 126                         unsigned tmp;
 127                         const char *tmp_c;
 128                         tmp = mode1; mode1 = mode2; mode2 = tmp;
 129                         tmp_c = name1; name1 = name2; name2 = tmp_c;
 130                 }
 131
 132                 if (!name1)
 133                         name1 = "/dev/null";
 134                 if (!name2)
 135                         name2 = "/dev/null";
 136                 d1 = alloc_filespec(name1);
 137                 d2 = alloc_filespec(name2);
 138                 fill_filespec(d1, null_sha1, mode1);
 139                 fill_filespec(d2, null_sha1, mode2);
 140
 141                 diff_queue(&diff_queued_diff, d1, d2);
 142                 return 0;
 143         }
 144 }
 145
 146 /*
 147  * Does the path name a blob in the working tree, or a directory
 148  * in the working tree?
 149  */
 150 static int is_in_index(const char *path)
 151 {
 152         int len, pos;
 153         struct cache_entry *ce;
 154
 155         len = strlen(path);
 156         while (path[len-1] == '/')
 157                 len--;
 158         if (!len)
 159                 return 1; /* "." */
 160         pos = cache_name_pos(path, len);
 161         if (0 <= pos)
 162                 return 1;
 163         pos = -1 - pos;
 164         while (pos < active_nr) {
 165                 ce = active_cache[pos++];
 166                 if (ce_namelen(ce) <= len ||
 167                     strncmp(ce->name, path, len) ||
 168                     (ce->name[len] > '/'))
 169                         break; /* path cannot be a prefix */
 170                 if (ce->name[len] == '/')
 171                         return 1;
 172         }
 173         return 0;
 174 }
 175
 176 static int handle_diff_files_args(struct rev_info *revs,
 177                                   int argc, const char **argv,
 178                                   unsigned int *options)
 179 {
 180         *options = 0;
 181
 182         /* revs->max_count == -2 means --no-index */
 183         while (1 < argc && argv[1][0] == '-') {
 184                 if (!strcmp(argv[1], "--base"))
 185                         revs->max_count = 1;
 186                 else if (!strcmp(argv[1], "--ours"))
 187                         revs->max_count = 2;
 188                 else if (!strcmp(argv[1], "--theirs"))
 189                         revs->max_count = 3;
 190                 else if (!strcmp(argv[1], "-n") ||
 191                                 !strcmp(argv[1], "--no-index")) {
 192                         revs->max_count = -2;
 193                         DIFF_OPT_SET(&revs->diffopt, EXIT_WITH_STATUS);
 194                         DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
 195                 }
 196                 else if (!strcmp(argv[1], "-q"))
 197                         *options |= DIFF_SILENT_ON_REMOVED;
 198                 else
 199                         return error("invalid option: %s", argv[1]);
 200                 argv++; argc--;
 201         }
 202
 203         if (revs->max_count == -1 && revs->diffopt.nr_paths == 2) {
 204                 /*
 205                  * If two files are specified, and at least one is untracked,
 206                  * default to no-index.
 207                  */
 208                 read_cache();
 209                 if (!is_in_index(revs->diffopt.paths[0]) ||
 210                                         !is_in_index(revs->diffopt.paths[1])) {
 211                         revs->max_count = -2;
 212                         DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
 213                 }
 214         }
 215
 216         /*
 217          * Make sure there are NO revision (i.e. pending object) parameter,
 218          * rev.max_count is reasonable (0 <= n <= 3),
 219          * there is no other revision filtering parameters.
 220          */
 221         if (revs->pending.nr || revs->max_count > 3 ||
 222             revs->min_age != -1 || revs->max_age != -1)
 223                 return error("no revision allowed with diff-files");
 224
 225         if (revs->max_count == -1 &&
 226             (revs->diffopt.output_format & DIFF_FORMAT_PATCH))
 227                 revs->combine_merges = revs->dense_combined_merges = 1;
 228
 229         return 0;
 230 }
 231
 232 static int is_outside_repo(const char *path, int nongit, const char *prefix)
 233 {
 234         int i;
 235         if (nongit || !strcmp(path, "-") || is_absolute_path(path))
 236                 return 1;
 237         if (prefixcmp(path, "../"))
 238                 return 0;
 239         if (!prefix)
 240                 return 1;
 241         for (i = strlen(prefix); !prefixcmp(path, "../"); ) {
 242                 while (i > 0 && prefix[i - 1] != '/')
 243                         i--;
 244                 if (--i < 0)
 245                         return 1;
 246                 path += 3;
 247         }
 248         return 0;
 249 }
 250
 251 int setup_diff_no_index(struct rev_info *revs,
 252                 int argc, const char ** argv, int nongit, const char *prefix)
 253 {
 254         int i;
 255         for (i = 1; i < argc; i++)
 256                 if (argv[i][0] != '-' || argv[i][1] == '\0')
 257                         break;
 258                 else if (!strcmp(argv[i], "--")) {
 259                         i++;
 260                         break;
 261                 } else if (i < argc - 3 && !strcmp(argv[i], "--no-index")) {
 262                         i = argc - 3;
 263                         DIFF_OPT_SET(&revs->diffopt, EXIT_WITH_STATUS);
 264                         break;
 265                 }
 266         if (argc != i + 2 || (!is_outside_repo(argv[i + 1], nongit, prefix) &&
 267                                 !is_outside_repo(argv[i], nongit, prefix)))
 268                 return -1;
 269
 270         diff_setup(&revs->diffopt);
 271         for (i = 1; i < argc - 2; )
 272                 if (!strcmp(argv[i], "--no-index"))
 273                         i++;
 274                 else {
 275                         int j = diff_opt_parse(&revs->diffopt,
 276                                         argv + i, argc - i);
 277                         if (!j)
 278                                 die("invalid diff option/value: %s", argv[i]);
 279                         i += j;
 280                 }
 281
 282         if (prefix) {
 283                 int len = strlen(prefix);
 284
 285                 revs->diffopt.paths = xcalloc(2, sizeof(char*));
 286                 for (i = 0; i < 2; i++) {
 287                         const char *p = argv[argc - 2 + i];
 288                         /*
 289                          * stdin should be spelled as '-'; if you have
 290                          * path that is '-', spell it as ./-.
 291                          */
 292                         p = (strcmp(p, "-")
 293                              ? xstrdup(prefix_filename(prefix, len, p))
 294                              : p);
 295                         revs->diffopt.paths[i] = p;
 296                 }
 297         }
 298         else
 299                 revs->diffopt.paths = argv + argc - 2;
 300         revs->diffopt.nr_paths = 2;
 301         DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
 302         revs->max_count = -2;
 303         if (diff_setup_done(&revs->diffopt) < 0)
 304                 die("diff_setup_done failed");
 305         return 0;
 306 }
 307
 308 int run_diff_files_cmd(struct rev_info *revs, int argc, const char **argv)
 309 {
 310         unsigned int options;
 311
 312         if (handle_diff_files_args(revs, argc, argv, &options))
 313                 return -1;
 314
 315         if (DIFF_OPT_TST(&revs->diffopt, NO_INDEX)) {
 316                 if (revs->diffopt.nr_paths != 2)
 317                         return error("need two files/directories with --no-index");
 318                 if (queue_diff(&revs->diffopt, revs->diffopt.paths[0],
 319                                 revs->diffopt.paths[1]))
 320                         return -1;
 321                 diffcore_std(&revs->diffopt);
 322                 diff_flush(&revs->diffopt);
 323                 /*
 324                  * The return code for --no-index imitates diff(1):
 325                  * 0 = no changes, 1 = changes, else error
 326                  */
 327                 return revs->diffopt.found_changes;
 328         }
 329
 330         if (read_cache() < 0) {
 331                 perror("read_cache");
 332                 return -1;
 333         }
 334         return run_diff_files(revs, options);
 335 }
 336
 337 int run_diff_files(struct rev_info *revs, unsigned int option)
 338 {
 339         int entries, i;
 340         int diff_unmerged_stage = revs->max_count;
 341         int silent_on_removed = option & DIFF_SILENT_ON_REMOVED;
 342         unsigned ce_option = ((option & DIFF_RACY_IS_MODIFIED)
 343                               ? CE_MATCH_RACY_IS_DIRTY : 0);
 344
 345         if (diff_unmerged_stage < 0)
 346                 diff_unmerged_stage = 2;
 347         entries = active_nr;
 348         for (i = 0; i < entries; i++) {
 349                 struct stat st;
 350                 unsigned int oldmode, newmode;
 351                 struct cache_entry *ce = active_cache[i];
 352                 int changed;
 353
 354                 if (DIFF_OPT_TST(&revs->diffopt, QUIET) &&
 355                         DIFF_OPT_TST(&revs->diffopt, HAS_CHANGES))
 356                         break;
 357
 358                 if (!ce_path_match(ce, revs->prune_data))
 359                         continue;
 360
 361                 if (ce_stage(ce)) {
 362                         struct combine_diff_path *dpath;
 363                         int num_compare_stages = 0;
 364                         size_t path_len;
 365
 366                         path_len = ce_namelen(ce);
 367
 368                         dpath = xmalloc(combine_diff_path_size(5, path_len));
 369                         dpath->path = (char *) &(dpath->parent[5]);
 370
 371                         dpath->next = NULL;
 372                         dpath->len = path_len;
 373                         memcpy(dpath->path, ce->name, path_len);
 374                         dpath->path[path_len] = '\0';
 375                         hashclr(dpath->sha1);
 376                         memset(&(dpath->parent[0]), 0,
 377                                sizeof(struct combine_diff_parent)*5);
 378
 379                         if (lstat(ce->name, &st) < 0) {
 380                                 if (errno != ENOENT && errno != ENOTDIR) {
 381                                         perror(ce->name);
 382                                         continue;
 383                                 }
 384                                 if (silent_on_removed)
 385                                         continue;
 386                         }
 387                         else
 388                                 dpath->mode = ce_mode_from_stat(ce, st.st_mode);
 389
 390                         while (i < entries) {
 391                                 struct cache_entry *nce = active_cache[i];
 392                                 int stage;
 393
 394                                 if (strcmp(ce->name, nce->name))
 395                                         break;
 396
 397                                 /* Stage #2 (ours) is the first parent,
 398                                  * stage #3 (theirs) is the second.
 399                                  */
 400                                 stage = ce_stage(nce);
 401                                 if (2 <= stage) {
 402                                         int mode = nce->ce_mode;
 403                                         num_compare_stages++;
 404                                         hashcpy(dpath->parent[stage-2].sha1, nce->sha1);
 405                                         dpath->parent[stage-2].mode = ce_mode_from_stat(nce, mode);
 406                                         dpath->parent[stage-2].status =
 407                                                 DIFF_STATUS_MODIFIED;
 408                                 }
 409
 410                                 /* diff against the proper unmerged stage */
 411                                 if (stage == diff_unmerged_stage)
 412                                         ce = nce;
 413                                 i++;
 414                         }
 415                         /*
 416                          * Compensate for loop update
 417                          */
 418                         i--;
 419
 420                         if (revs->combine_merges && num_compare_stages == 2) {
 421                                 show_combined_diff(dpath, 2,
 422                                                    revs->dense_combined_merges,
 423                                                    revs);
 424                                 free(dpath);
 425                                 continue;
 426                         }
 427                         free(dpath);
 428                         dpath = NULL;
 429
 430                         /*
 431                          * Show the diff for the 'ce' if we found the one
 432                          * from the desired stage.
 433                          */
 434                         diff_unmerge(&revs->diffopt, ce->name, 0, null_sha1);
 435                         if (ce_stage(ce) != diff_unmerged_stage)
 436                                 continue;
 437                 }
 438
 439                 if (ce_uptodate(ce))
 440                         continue;
 441                 if (lstat(ce->name, &st) < 0) {
 442                         if (errno != ENOENT && errno != ENOTDIR) {
 443                                 perror(ce->name);
 444                                 continue;
 445                         }
 446                         if (silent_on_removed)
 447                                 continue;
 448                         diff_addremove(&revs->diffopt, '-', ce->ce_mode,
 449                                        ce->sha1, ce->name, NULL);
 450                         continue;
 451                 }
 452                 changed = ce_match_stat(ce, &st, ce_option);
 453                 if (!changed && !DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER))
 454                         continue;
 455                 oldmode = ce->ce_mode;
 456                 newmode = ce_mode_from_stat(ce, st.st_mode);
 457                 diff_change(&revs->diffopt, oldmode, newmode,
 458                             ce->sha1, (changed ? null_sha1 : ce->sha1),
 459                             ce->name, NULL);
 460
 461         }
 462         diffcore_std(&revs->diffopt);
 463         diff_flush(&revs->diffopt);
 464         return 0;
 465 }
 466
 467 /*
 468  * diff-index
 469  */
 470
 471 /* A file entry went away or appeared */
 472 static void diff_index_show_file(struct rev_info *revs,
 473                                  const char *prefix,
 474                                  struct cache_entry *ce,
 475                                  unsigned char *sha1, unsigned int mode)
 476 {
 477         diff_addremove(&revs->diffopt, prefix[0], mode,
 478                        sha1, ce->name, NULL);
 479 }
 480
 481 static int get_stat_data(struct cache_entry *ce,
 482                          unsigned char **sha1p,
 483                          unsigned int *modep,
 484                          int cached, int match_missing)
 485 {
 486         unsigned char *sha1 = ce->sha1;
 487         unsigned int mode = ce->ce_mode;
 488
 489         if (!cached) {
 490                 static unsigned char no_sha1[20];
 491                 int changed;
 492                 struct stat st;
 493                 if (lstat(ce->name, &st) < 0) {
 494                         if (errno == ENOENT && match_missing) {
 495                                 *sha1p = sha1;
 496                                 *modep = mode;
 497                                 return 0;
 498                         }
 499                         return -1;
 500                 }
 501                 changed = ce_match_stat(ce, &st, 0);
 502                 if (changed) {
 503                         mode = ce_mode_from_stat(ce, st.st_mode);
 504                         sha1 = no_sha1;
 505                 }
 506         }
 507
 508         *sha1p = sha1;
 509         *modep = mode;
 510         return 0;
 511 }
 512
 513 static void show_new_file(struct rev_info *revs,
 514                           struct cache_entry *new,
 515                           int cached, int match_missing)
 516 {
 517         unsigned char *sha1;
 518         unsigned int mode;
 519
 520         /* New file in the index: it might actually be different in
 521          * the working copy.
 522          */
 523         if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0)
 524                 return;
 525
 526         diff_index_show_file(revs, "+", new, sha1, mode);
 527 }
 528
 529 static int show_modified(struct rev_info *revs,
 530                          struct cache_entry *old,
 531                          struct cache_entry *new,
 532                          int report_missing,
 533                          int cached, int match_missing)
 534 {
 535         unsigned int mode, oldmode;
 536         unsigned char *sha1;
 537
 538         if (get_stat_data(new, &sha1, &mode, cached, match_missing) < 0) {
 539                 if (report_missing)
 540                         diff_index_show_file(revs, "-", old,
 541                                              old->sha1, old->ce_mode);
 542                 return -1;
 543         }
 544
 545         if (revs->combine_merges && !cached &&
 546             (hashcmp(sha1, old->sha1) || hashcmp(old->sha1, new->sha1))) {
 547                 struct combine_diff_path *p;
 548                 int pathlen = ce_namelen(new);
 549
 550                 p = xmalloc(combine_diff_path_size(2, pathlen));
 551                 p->path = (char *) &p->parent[2];
 552                 p->next = NULL;
 553                 p->len = pathlen;
 554                 memcpy(p->path, new->name, pathlen);
 555                 p->path[pathlen] = 0;
 556                 p->mode = mode;
 557                 hashclr(p->sha1);
 558                 memset(p->parent, 0, 2 * sizeof(struct combine_diff_parent));
 559                 p->parent[0].status = DIFF_STATUS_MODIFIED;
 560                 p->parent[0].mode = new->ce_mode;
 561                 hashcpy(p->parent[0].sha1, new->sha1);
 562                 p->parent[1].status = DIFF_STATUS_MODIFIED;
 563                 p->parent[1].mode = old->ce_mode;
 564                 hashcpy(p->parent[1].sha1, old->sha1);
 565                 show_combined_diff(p, 2, revs->dense_combined_merges, revs);
 566                 free(p);
 567                 return 0;
 568         }
 569
 570         oldmode = old->ce_mode;
 571         if (mode == oldmode && !hashcmp(sha1, old->sha1) &&
 572             !DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER))
 573                 return 0;
 574
 575         diff_change(&revs->diffopt, oldmode, mode,
 576                     old->sha1, sha1, old->name, NULL);
 577         return 0;
 578 }
 579
 580 static int diff_cache(struct rev_info *revs,
 581                       struct cache_entry **ac, int entries,
 582                       const char **pathspec,
 583                       int cached, int match_missing)
 584 {
 585         while (entries) {
 586                 struct cache_entry *ce = *ac;
 587                 int same = (entries > 1) && ce_same_name(ce, ac[1]);
 588
 589                 if (DIFF_OPT_TST(&revs->diffopt, QUIET) &&
 590                         DIFF_OPT_TST(&revs->diffopt, HAS_CHANGES))
 591                         break;
 592
 593                 if (!ce_path_match(ce, pathspec))
 594                         goto skip_entry;
 595
 596                 switch (ce_stage(ce)) {
 597                 case 0:
 598                         /* No stage 1 entry? That means it's a new file */
 599                         if (!same) {
 600                                 show_new_file(revs, ce, cached, match_missing);
 601                                 break;
 602                         }
 603                         /* Show difference between old and new */
 604                         show_modified(revs, ac[1], ce, 1,
 605                                       cached, match_missing);
 606                         break;
 607                 case 1:
 608                         /* No stage 3 (merge) entry?
 609                          * That means it's been deleted.
 610                          */
 611                         if (!same) {
 612                                 diff_index_show_file(revs, "-", ce,
 613                                                      ce->sha1, ce->ce_mode);
 614                                 break;
 615                         }
 616                         /* We come here with ce pointing at stage 1
 617                          * (original tree) and ac[1] pointing at stage
 618                          * 3 (unmerged).  show-modified with
 619                          * report-missing set to false does not say the
 620                          * file is deleted but reports true if work
 621                          * tree does not have it, in which case we
 622                          * fall through to report the unmerged state.
 623                          * Otherwise, we show the differences between
 624                          * the original tree and the work tree.
 625                          */
 626                         if (!cached &&
 627                             !show_modified(revs, ce, ac[1], 0,
 628                                            cached, match_missing))
 629                                 break;
 630                         diff_unmerge(&revs->diffopt, ce->name,
 631                                      ce->ce_mode, ce->sha1);
 632                         break;
 633                 case 3:
 634                         diff_unmerge(&revs->diffopt, ce->name,
 635                                      0, null_sha1);
 636                         break;
 637
 638                 default:
 639                         die("impossible cache entry stage");
 640                 }
 641
 642 skip_entry:
 643                 /*
 644                  * Ignore all the different stages for this file,
 645                  * we've handled the relevant cases now.
 646                  */
 647                 do {
 648                         ac++;
 649                         entries--;
 650                 } while (entries && ce_same_name(ce, ac[0]));
 651         }
 652         return 0;
 653 }
 654
 655 /*
 656  * This turns all merge entries into "stage 3". That guarantees that
 657  * when we read in the new tree (into "stage 1"), we won't lose sight
 658  * of the fact that we had unmerged entries.
 659  */
 660 static void mark_merge_entries(void)
 661 {
 662         int i;
 663         for (i = 0; i < active_nr; i++) {
 664                 struct cache_entry *ce = active_cache[i];
 665                 if (!ce_stage(ce))
 666                         continue;
 667                 ce->ce_flags |= CE_STAGEMASK;
 668         }
 669 }
 670
 671 /*
 672  * This gets a mix of an existing index and a tree, one pathname entry
 673  * at a time. The index entry may be a single stage-0 one, but it could
 674  * also be multiple unmerged entries (in which case idx_pos/idx_nr will
 675  * give you the position and number of entries in the index).
 676  */
 677 static void do_oneway_diff(struct unpack_trees_options *o,
 678         struct cache_entry *idx,
 679         struct cache_entry *tree,
 680         int idx_pos, int idx_nr)
 681 {
 682         struct rev_info *revs = o->unpack_data;
 683         int match_missing, cached;
 684
 685         /*
 686          * Backward compatibility wart - "diff-index -m" does
 687          * not mean "do not ignore merges", but "match_missing".
 688          *
 689          * But with the revision flag parsing, that's found in
 690          * "!revs->ignore_merges".
 691          */
 692         cached = o->index_only;
 693         match_missing = !revs->ignore_merges;
 694
 695         if (cached && idx && ce_stage(idx)) {
 696                 if (tree)
 697                         diff_unmerge(&revs->diffopt, idx->name, idx->ce_mode, idx->sha1);
 698                 return;
 699         }
 700
 701         /*
 702          * Something added to the tree?
 703          */
 704         if (!tree) {
 705                 show_new_file(revs, idx, cached, match_missing);
 706                 return;
 707         }
 708
 709         /*
 710          * Something removed from the tree?
 711          */
 712         if (!idx) {
 713                 diff_index_show_file(revs, "-", tree, tree->sha1, tree->ce_mode);
 714                 return;
 715         }
 716
 717         /* Show difference between old and new */
 718         show_modified(revs, tree, idx, 1, cached, match_missing);
 719 }
 720
 721 /*
 722  * Count how many index entries go with the first one
 723  */
 724 static inline int count_skip(const struct cache_entry *src, int pos)
 725 {
 726         int skip = 1;
 727
 728         /* We can only have multiple entries if the first one is not stage-0 */
 729         if (ce_stage(src)) {
 730                 struct cache_entry **p = active_cache + pos;
 731                 int namelen = ce_namelen(src);
 732
 733                 for (;;) {
 734                         const struct cache_entry *ce;
 735                         pos++;
 736                         if (pos >= active_nr)
 737                                 break;
 738                         ce = *++p;
 739                         if (ce_namelen(ce) != namelen)
 740                                 break;
 741                         if (memcmp(ce->name, src->name, namelen))
 742                                 break;
 743                         skip++;
 744                 }
 745         }
 746         return skip;
 747 }
 748
 749 /*
 750  * The unpack_trees() interface is designed for merging, so
 751  * the different source entries are designed primarily for
 752  * the source trees, with the old index being really mainly
 753  * used for being replaced by the result.
 754  *
 755  * For diffing, the index is more important, and we only have a
 756  * single tree.
 757  *
 758  * We're supposed to return how many index entries we want to skip.
 759  *
 760  * This wrapper makes it all more readable, and takes care of all
 761  * the fairly complex unpack_trees() semantic requirements, including
 762  * the skipping, the path matching, the type conflict cases etc.
 763  */
 764 static int oneway_diff(struct cache_entry **src,
 765         struct unpack_trees_options *o,
 766         int index_pos)
 767 {
 768         int skip = 0;
 769         struct cache_entry *idx = src[0];
 770         struct cache_entry *tree = src[1];
 771         struct rev_info *revs = o->unpack_data;
 772
 773         if (index_pos >= 0)
 774                 skip = count_skip(idx, index_pos);
 775
 776         /*
 777          * Unpack-trees generates a DF/conflict entry if
 778          * there was a directory in the index and a tree
 779          * in the tree. From a diff standpoint, that's a
 780          * delete of the tree and a create of the file.
 781          */
 782         if (tree == o->df_conflict_entry)
 783                 tree = NULL;
 784
 785         if (ce_path_match(idx ? idx : tree, revs->prune_data))
 786                 do_oneway_diff(o, idx, tree, index_pos, skip);
 787
 788         return skip;
 789 }
 790
 791 int run_diff_index(struct rev_info *revs, int cached)
 792 {
 793         struct object *ent;
 794         struct tree *tree;
 795         const char *tree_name;
 796         struct unpack_trees_options opts;
 797         struct tree_desc t;
 798
 799         mark_merge_entries();
 800
 801         ent = revs->pending.objects[0].item;
 802         tree_name = revs->pending.objects[0].name;
 803         tree = parse_tree_indirect(ent->sha1);
 804         if (!tree)
 805                 return error("bad tree object %s", tree_name);
 806
 807         memset(&opts, 0, sizeof(opts));
 808         opts.head_idx = 1;
 809         opts.index_only = cached;
 810         opts.merge = 1;
 811         opts.fn = oneway_diff;
 812         opts.unpack_data = revs;
 813
 814         init_tree_desc(&t, tree->buffer, tree->size);
 815         unpack_trees(1, &t, &opts);
 816
 817         diffcore_std(&revs->diffopt);
 818         diff_flush(&revs->diffopt);
 819         return 0;
 820 }
 821
 822 int do_diff_cache(const unsigned char *tree_sha1, struct diff_options *opt)
 823 {
 824         struct tree *tree;
 825         struct rev_info revs;
 826         int i;
 827         struct cache_entry **dst;
 828         struct cache_entry *last = NULL;
 829
 830         /*
 831          * This is used by git-blame to run diff-cache internally;
 832          * it potentially needs to repeatedly run this, so we will
 833          * start by removing the higher order entries the last round
 834          * left behind.
 835          */
 836         dst = active_cache;
 837         for (i = 0; i < active_nr; i++) {
 838                 struct cache_entry *ce = active_cache[i];
 839                 if (ce_stage(ce)) {
 840                         if (last && !strcmp(ce->name, last->name))
 841                                 continue;
 842                         cache_tree_invalidate_path(active_cache_tree,
 843                                                    ce->name);
 844                         last = ce;
 845                         ce->ce_flags |= CE_REMOVE;
 846                 }
 847                 *dst++ = ce;
 848         }
 849         active_nr = dst - active_cache;
 850
 851         init_revisions(&revs, NULL);
 852         revs.prune_data = opt->paths;
 853         tree = parse_tree_indirect(tree_sha1);
 854         if (!tree)
 855                 die("bad tree object %s", sha1_to_hex(tree_sha1));
 856         if (read_tree(tree, 1, opt->paths))
 857                 return error("unable to read tree %s", sha1_to_hex(tree_sha1));
 858         return diff_cache(&revs, active_cache, active_nr, revs.prune_data,
 859                           1, 0);
 860 }