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 (argc != i + 2 || (!is_outside_repo(argv[i + 1], nongit, prefix) &&
 268                                 !is_outside_repo(argv[i], nongit, prefix)))
 269                 return -1;
 270
 271         diff_setup(&revs->diffopt);
 272         for (i = 1; i < argc - 2; )
 273                 if (!strcmp(argv[i], "--no-index"))
 274                         i++;
 275                 else {
 276                         int j = diff_opt_parse(&revs->diffopt,
 277                                         argv + i, argc - i);
 278                         if (!j)
 279                                 die("invalid diff option/value: %s", argv[i]);
 280                         i += j;
 281                 }
 282
 283         if (prefix) {
 284                 int len = strlen(prefix);
 285
 286                 revs->diffopt.paths = xcalloc(2, sizeof(char*));
 287                 for (i = 0; i < 2; i++) {
 288                         const char *p = argv[argc - 2 + i];
 289                         /*
 290                          * stdin should be spelled as '-'; if you have
 291                          * path that is '-', spell it as ./-.
 292                          */
 293                         p = (strcmp(p, "-")
 294                              ? xstrdup(prefix_filename(prefix, len, p))
 295                              : p);
 296                         revs->diffopt.paths[i] = p;
 297                 }
 298         }
 299         else
 300                 revs->diffopt.paths = argv + argc - 2;
 301         revs->diffopt.nr_paths = 2;
 302         DIFF_OPT_SET(&revs->diffopt, NO_INDEX);
 303         revs->max_count = -2;
 304         if (diff_setup_done(&revs->diffopt) < 0)
 305                 die("diff_setup_done failed");
 306         return 0;
 307 }
 308
 309 int run_diff_files_cmd(struct rev_info *revs, int argc, const char **argv)
 310 {
 311         unsigned int options;
 312
 313         if (handle_diff_files_args(revs, argc, argv, &options))
 314                 return -1;
 315
 316         if (DIFF_OPT_TST(&revs->diffopt, NO_INDEX)) {
 317                 if (revs->diffopt.nr_paths != 2)
 318                         return error("need two files/directories with --no-index");
 319                 if (queue_diff(&revs->diffopt, revs->diffopt.paths[0],
 320                                 revs->diffopt.paths[1]))
 321                         return -1;
 322                 diffcore_std(&revs->diffopt);
 323                 diff_flush(&revs->diffopt);
 324                 /*
 325                  * The return code for --no-index imitates diff(1):
 326                  * 0 = no changes, 1 = changes, else error
 327                  */
 328                 return revs->diffopt.found_changes;
 329         }
 330
 331         if (read_cache() < 0) {
 332                 perror("read_cache");
 333                 return -1;
 334         }
 335         return run_diff_files(revs, options);
 336 }
 337 /*
 338  * See if work tree has an entity that can be staged.  Return 0 if so,
 339  * return 1 if not and return -1 if error.
 340  */
 341 static int check_work_tree_entity(const struct cache_entry *ce, struct stat *st, char *symcache)
 342 {
 343         if (lstat(ce->name, st) < 0) {
 344                 if (errno != ENOENT && errno != ENOTDIR)
 345                         return -1;
 346                 return 1;
 347         }
 348         if (has_symlink_leading_path(ce->name, symcache))
 349                 return 1;
 350         if (S_ISDIR(st->st_mode)) {
 351                 unsigned char sub[20];
 352                 if (resolve_gitlink_ref(ce->name, "HEAD", sub))
 353                         return 1;
 354         }
 355         return 0;
 356 }
 357
 358 int run_diff_files(struct rev_info *revs, unsigned int option)
 359 {
 360         int entries, i;
 361         int diff_unmerged_stage = revs->max_count;
 362         int silent_on_removed = option & DIFF_SILENT_ON_REMOVED;
 363         unsigned ce_option = ((option & DIFF_RACY_IS_MODIFIED)
 364                               ? CE_MATCH_RACY_IS_DIRTY : 0);
 365         char symcache[PATH_MAX];
 366
 367         if (diff_unmerged_stage < 0)
 368                 diff_unmerged_stage = 2;
 369         entries = active_nr;
 370         symcache[0] = '\0';
 371         for (i = 0; i < entries; i++) {
 372                 struct stat st;
 373                 unsigned int oldmode, newmode;
 374                 struct cache_entry *ce = active_cache[i];
 375                 int changed;
 376
 377                 if (DIFF_OPT_TST(&revs->diffopt, QUIET) &&
 378                         DIFF_OPT_TST(&revs->diffopt, HAS_CHANGES))
 379                         break;
 380
 381                 if (!ce_path_match(ce, revs->prune_data))
 382                         continue;
 383
 384                 if (ce_stage(ce)) {
 385                         struct combine_diff_path *dpath;
 386                         int num_compare_stages = 0;
 387                         size_t path_len;
 388
 389                         path_len = ce_namelen(ce);
 390
 391                         dpath = xmalloc(combine_diff_path_size(5, path_len));
 392                         dpath->path = (char *) &(dpath->parent[5]);
 393
 394                         dpath->next = NULL;
 395                         dpath->len = path_len;
 396                         memcpy(dpath->path, ce->name, path_len);
 397                         dpath->path[path_len] = '\0';
 398                         hashclr(dpath->sha1);
 399                         memset(&(dpath->parent[0]), 0,
 400                                sizeof(struct combine_diff_parent)*5);
 401
 402                         changed = check_work_tree_entity(ce, &st, symcache);
 403                         if (!changed)
 404                                 dpath->mode = ce_mode_from_stat(ce, st.st_mode);
 405                         else {
 406                                 if (changed < 0) {
 407                                         perror(ce->name);
 408                                         continue;
 409                                 }
 410                                 if (silent_on_removed)
 411                                         continue;
 412                         }
 413
 414                         while (i < entries) {
 415                                 struct cache_entry *nce = active_cache[i];
 416                                 int stage;
 417
 418                                 if (strcmp(ce->name, nce->name))
 419                                         break;
 420
 421                                 /* Stage #2 (ours) is the first parent,
 422                                  * stage #3 (theirs) is the second.
 423                                  */
 424                                 stage = ce_stage(nce);
 425                                 if (2 <= stage) {
 426                                         int mode = nce->ce_mode;
 427                                         num_compare_stages++;
 428                                         hashcpy(dpath->parent[stage-2].sha1, nce->sha1);
 429                                         dpath->parent[stage-2].mode = ce_mode_from_stat(nce, mode);
 430                                         dpath->parent[stage-2].status =
 431                                                 DIFF_STATUS_MODIFIED;
 432                                 }
 433
 434                                 /* diff against the proper unmerged stage */
 435                                 if (stage == diff_unmerged_stage)
 436                                         ce = nce;
 437                                 i++;
 438                         }
 439                         /*
 440                          * Compensate for loop update
 441                          */
 442                         i--;
 443
 444                         if (revs->combine_merges && num_compare_stages == 2) {
 445                                 show_combined_diff(dpath, 2,
 446                                                    revs->dense_combined_merges,
 447                                                    revs);
 448                                 free(dpath);
 449                                 continue;
 450                         }
 451                         free(dpath);
 452                         dpath = NULL;
 453
 454                         /*
 455                          * Show the diff for the 'ce' if we found the one
 456                          * from the desired stage.
 457                          */
 458                         diff_unmerge(&revs->diffopt, ce->name, 0, null_sha1);
 459                         if (ce_stage(ce) != diff_unmerged_stage)
 460                                 continue;
 461                 }
 462
 463                 if (ce_uptodate(ce))
 464                         continue;
 465
 466                 changed = check_work_tree_entity(ce, &st, symcache);
 467                 if (changed) {
 468                         if (changed < 0) {
 469                                 perror(ce->name);
 470                                 continue;
 471                         }
 472                         if (silent_on_removed)
 473                                 continue;
 474                         diff_addremove(&revs->diffopt, '-', ce->ce_mode,
 475                                        ce->sha1, ce->name, NULL);
 476                         continue;
 477                 }
 478                 changed = ce_match_stat(ce, &st, ce_option);
 479                 if (!changed && !DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER))
 480                         continue;
 481                 oldmode = ce->ce_mode;
 482                 newmode = ce_mode_from_stat(ce, st.st_mode);
 483                 diff_change(&revs->diffopt, oldmode, newmode,
 484                             ce->sha1, (changed ? null_sha1 : ce->sha1),
 485                             ce->name, NULL);
 486
 487         }
 488         diffcore_std(&revs->diffopt);
 489         diff_flush(&revs->diffopt);
 490         return 0;
 491 }
 492
 493 /*
 494  * diff-index
 495  */
 496
 497 struct oneway_unpack_data {
 498         struct rev_info *revs;
 499         char symcache[PATH_MAX];
 500 };
 501
 502 /* A file entry went away or appeared */
 503 static void diff_index_show_file(struct rev_info *revs,
 504                                  const char *prefix,
 505                                  struct cache_entry *ce,
 506                                  const unsigned char *sha1, unsigned int mode)
 507 {
 508         diff_addremove(&revs->diffopt, prefix[0], mode,
 509                        sha1, ce->name, NULL);
 510 }
 511
 512 static int get_stat_data(struct cache_entry *ce,
 513                          const unsigned char **sha1p,
 514                          unsigned int *modep,
 515                          int cached, int match_missing,
 516                          struct oneway_unpack_data *cbdata)
 517 {
 518         const unsigned char *sha1 = ce->sha1;
 519         unsigned int mode = ce->ce_mode;
 520
 521         if (!cached) {
 522                 int changed;
 523                 struct stat st;
 524                 changed = check_work_tree_entity(ce, &st, cbdata->symcache);
 525                 if (changed < 0)
 526                         return -1;
 527                 else if (changed) {
 528                         if (match_missing) {
 529                                 *sha1p = sha1;
 530                                 *modep = mode;
 531                                 return 0;
 532                         }
 533                         return -1;
 534                 }
 535                 changed = ce_match_stat(ce, &st, 0);
 536                 if (changed) {
 537                         mode = ce_mode_from_stat(ce, st.st_mode);
 538                         sha1 = null_sha1;
 539                 }
 540         }
 541
 542         *sha1p = sha1;
 543         *modep = mode;
 544         return 0;
 545 }
 546
 547 static void show_new_file(struct oneway_unpack_data *cbdata,
 548                           struct cache_entry *new,
 549                           int cached, int match_missing)
 550 {
 551         const unsigned char *sha1;
 552         unsigned int mode;
 553         struct rev_info *revs = cbdata->revs;
 554
 555         /*
 556          * New file in the index: it might actually be different in
 557          * the working copy.
 558          */
 559         if (get_stat_data(new, &sha1, &mode, cached, match_missing, cbdata) < 0)
 560                 return;
 561
 562         diff_index_show_file(revs, "+", new, sha1, mode);
 563 }
 564
 565 static int show_modified(struct oneway_unpack_data *cbdata,
 566                          struct cache_entry *old,
 567                          struct cache_entry *new,
 568                          int report_missing,
 569                          int cached, int match_missing)
 570 {
 571         unsigned int mode, oldmode;
 572         const unsigned char *sha1;
 573         struct rev_info *revs = cbdata->revs;
 574
 575         if (get_stat_data(new, &sha1, &mode, cached, match_missing, cbdata) < 0) {
 576                 if (report_missing)
 577                         diff_index_show_file(revs, "-", old,
 578                                              old->sha1, old->ce_mode);
 579                 return -1;
 580         }
 581
 582         if (revs->combine_merges && !cached &&
 583             (hashcmp(sha1, old->sha1) || hashcmp(old->sha1, new->sha1))) {
 584                 struct combine_diff_path *p;
 585                 int pathlen = ce_namelen(new);
 586
 587                 p = xmalloc(combine_diff_path_size(2, pathlen));
 588                 p->path = (char *) &p->parent[2];
 589                 p->next = NULL;
 590                 p->len = pathlen;
 591                 memcpy(p->path, new->name, pathlen);
 592                 p->path[pathlen] = 0;
 593                 p->mode = mode;
 594                 hashclr(p->sha1);
 595                 memset(p->parent, 0, 2 * sizeof(struct combine_diff_parent));
 596                 p->parent[0].status = DIFF_STATUS_MODIFIED;
 597                 p->parent[0].mode = new->ce_mode;
 598                 hashcpy(p->parent[0].sha1, new->sha1);
 599                 p->parent[1].status = DIFF_STATUS_MODIFIED;
 600                 p->parent[1].mode = old->ce_mode;
 601                 hashcpy(p->parent[1].sha1, old->sha1);
 602                 show_combined_diff(p, 2, revs->dense_combined_merges, revs);
 603                 free(p);
 604                 return 0;
 605         }
 606
 607         oldmode = old->ce_mode;
 608         if (mode == oldmode && !hashcmp(sha1, old->sha1) &&
 609             !DIFF_OPT_TST(&revs->diffopt, FIND_COPIES_HARDER))
 610                 return 0;
 611
 612         diff_change(&revs->diffopt, oldmode, mode,
 613                     old->sha1, sha1, old->name, NULL);
 614         return 0;
 615 }
 616
 617 /*
 618  * This turns all merge entries into "stage 3". That guarantees that
 619  * when we read in the new tree (into "stage 1"), we won't lose sight
 620  * of the fact that we had unmerged entries.
 621  */
 622 static void mark_merge_entries(void)
 623 {
 624         int i;
 625         for (i = 0; i < active_nr; i++) {
 626                 struct cache_entry *ce = active_cache[i];
 627                 if (!ce_stage(ce))
 628                         continue;
 629                 ce->ce_flags |= CE_STAGEMASK;
 630         }
 631 }
 632
 633 /*
 634  * This gets a mix of an existing index and a tree, one pathname entry
 635  * at a time. The index entry may be a single stage-0 one, but it could
 636  * also be multiple unmerged entries (in which case idx_pos/idx_nr will
 637  * give you the position and number of entries in the index).
 638  */
 639 static void do_oneway_diff(struct unpack_trees_options *o,
 640         struct cache_entry *idx,
 641         struct cache_entry *tree)
 642 {
 643         struct oneway_unpack_data *cbdata = o->unpack_data;
 644         struct rev_info *revs = cbdata->revs;
 645         int match_missing, cached;
 646
 647         /*
 648          * Backward compatibility wart - "diff-index -m" does
 649          * not mean "do not ignore merges", but "match_missing".
 650          *
 651          * But with the revision flag parsing, that's found in
 652          * "!revs->ignore_merges".
 653          */
 654         cached = o->index_only;
 655         match_missing = !revs->ignore_merges;
 656
 657         if (cached && idx && ce_stage(idx)) {
 658                 if (tree)
 659                         diff_unmerge(&revs->diffopt, idx->name, idx->ce_mode, idx->sha1);
 660                 return;
 661         }
 662
 663         /*
 664          * Something added to the tree?
 665          */
 666         if (!tree) {
 667                 show_new_file(cbdata, idx, cached, match_missing);
 668                 return;
 669         }
 670
 671         /*
 672          * Something removed from the tree?
 673          */
 674         if (!idx) {
 675                 diff_index_show_file(revs, "-", tree, tree->sha1, tree->ce_mode);
 676                 return;
 677         }
 678
 679         /* Show difference between old and new */
 680         show_modified(cbdata, tree, idx, 1, cached, match_missing);
 681 }
 682
 683 static inline void skip_same_name(struct cache_entry *ce, struct unpack_trees_options *o)
 684 {
 685         int len = ce_namelen(ce);
 686         const struct index_state *index = o->src_index;
 687
 688         while (o->pos < index->cache_nr) {
 689                 struct cache_entry *next = index->cache[o->pos];
 690                 if (len != ce_namelen(next))
 691                         break;
 692                 if (memcmp(ce->name, next->name, len))
 693                         break;
 694                 o->pos++;
 695         }
 696 }
 697
 698 /*
 699  * The unpack_trees() interface is designed for merging, so
 700  * the different source entries are designed primarily for
 701  * the source trees, with the old index being really mainly
 702  * used for being replaced by the result.
 703  *
 704  * For diffing, the index is more important, and we only have a
 705  * single tree.
 706  *
 707  * We're supposed to return how many index entries we want to skip.
 708  *
 709  * This wrapper makes it all more readable, and takes care of all
 710  * the fairly complex unpack_trees() semantic requirements, including
 711  * the skipping, the path matching, the type conflict cases etc.
 712  */
 713 static int oneway_diff(struct cache_entry **src, struct unpack_trees_options *o)
 714 {
 715         struct cache_entry *idx = src[0];
 716         struct cache_entry *tree = src[1];
 717         struct oneway_unpack_data *cbdata = o->unpack_data;
 718         struct rev_info *revs = cbdata->revs;
 719
 720         if (idx && ce_stage(idx))
 721                 skip_same_name(idx, o);
 722
 723         /*
 724          * Unpack-trees generates a DF/conflict entry if
 725          * there was a directory in the index and a tree
 726          * in the tree. From a diff standpoint, that's a
 727          * delete of the tree and a create of the file.
 728          */
 729         if (tree == o->df_conflict_entry)
 730                 tree = NULL;
 731
 732         if (ce_path_match(idx ? idx : tree, revs->prune_data))
 733                 do_oneway_diff(o, idx, tree);
 734
 735         return 0;
 736 }
 737
 738 int run_diff_index(struct rev_info *revs, int cached)
 739 {
 740         struct object *ent;
 741         struct tree *tree;
 742         const char *tree_name;
 743         struct unpack_trees_options opts;
 744         struct tree_desc t;
 745         struct oneway_unpack_data unpack_cb;
 746
 747         mark_merge_entries();
 748
 749         ent = revs->pending.objects[0].item;
 750         tree_name = revs->pending.objects[0].name;
 751         tree = parse_tree_indirect(ent->sha1);
 752         if (!tree)
 753                 return error("bad tree object %s", tree_name);
 754
 755         unpack_cb.revs = revs;
 756         unpack_cb.symcache[0] = '\0';
 757         memset(&opts, 0, sizeof(opts));
 758         opts.head_idx = 1;
 759         opts.index_only = cached;
 760         opts.merge = 1;
 761         opts.fn = oneway_diff;
 762         opts.unpack_data = &unpack_cb;
 763         opts.src_index = &the_index;
 764         opts.dst_index = NULL;
 765
 766         init_tree_desc(&t, tree->buffer, tree->size);
 767         if (unpack_trees(1, &t, &opts))
 768                 exit(128);
 769
 770         diffcore_std(&revs->diffopt);
 771         diff_flush(&revs->diffopt);
 772         return 0;
 773 }
 774
 775 int do_diff_cache(const unsigned char *tree_sha1, struct diff_options *opt)
 776 {
 777         struct tree *tree;
 778         struct rev_info revs;
 779         int i;
 780         struct cache_entry **dst;
 781         struct cache_entry *last = NULL;
 782         struct unpack_trees_options opts;
 783         struct tree_desc t;
 784         struct oneway_unpack_data unpack_cb;
 785
 786         /*
 787          * This is used by git-blame to run diff-cache internally;
 788          * it potentially needs to repeatedly run this, so we will
 789          * start by removing the higher order entries the last round
 790          * left behind.
 791          */
 792         dst = active_cache;
 793         for (i = 0; i < active_nr; i++) {
 794                 struct cache_entry *ce = active_cache[i];
 795                 if (ce_stage(ce)) {
 796                         if (last && !strcmp(ce->name, last->name))
 797                                 continue;
 798                         cache_tree_invalidate_path(active_cache_tree,
 799                                                    ce->name);
 800                         last = ce;
 801                         ce->ce_flags |= CE_REMOVE;
 802                 }
 803                 *dst++ = ce;
 804         }
 805         active_nr = dst - active_cache;
 806
 807         init_revisions(&revs, NULL);
 808         revs.prune_data = opt->paths;
 809         tree = parse_tree_indirect(tree_sha1);
 810         if (!tree)
 811                 die("bad tree object %s", sha1_to_hex(tree_sha1));
 812
 813         unpack_cb.revs = &revs;
 814         unpack_cb.symcache[0] = '\0';
 815         memset(&opts, 0, sizeof(opts));
 816         opts.head_idx = 1;
 817         opts.index_only = 1;
 818         opts.merge = 1;
 819         opts.fn = oneway_diff;
 820         opts.unpack_data = &unpack_cb;
 821         opts.src_index = &the_index;
 822         opts.dst_index = &the_index;
 823
 824         init_tree_desc(&t, tree->buffer, tree->size);
 825         if (unpack_trees(1, &t, &opts))
 826                 exit(128);
 827         return 0;
 828 }