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