unpack-trees.c

   1 #include "cache.h"
   2 #include "dir.h"
   3 #include "tree.h"
   4 #include "tree-walk.h"
   5 #include "cache-tree.h"
   6 #include "unpack-trees.h"
   7
   8 #define DBRT_DEBUG 1
   9
  10 struct tree_entry_list {
  11         struct tree_entry_list *next;
  12         unsigned directory : 1;
  13         unsigned executable : 1;
  14         unsigned symlink : 1;
  15         unsigned int mode;
  16         const char *name;
  17         const unsigned char *sha1;
  18 };
  19
  20 static struct tree_entry_list *create_tree_entry_list(struct tree *tree)
  21 {
  22         struct tree_desc desc;
  23         struct name_entry one;
  24         struct tree_entry_list *ret = NULL;
  25         struct tree_entry_list **list_p = &ret;
  26
  27         if (!tree->object.parsed)
  28                 parse_tree(tree);
  29
  30         init_tree_desc(&desc, tree->buffer, tree->size);
  31
  32         while (tree_entry(&desc, &one)) {
  33                 struct tree_entry_list *entry;
  34
  35                 entry = xmalloc(sizeof(struct tree_entry_list));
  36                 entry->name = one.path;
  37                 entry->sha1 = one.sha1;
  38                 entry->mode = one.mode;
  39                 entry->directory = S_ISDIR(one.mode) != 0;
  40                 entry->executable = (one.mode & S_IXUSR) != 0;
  41                 entry->symlink = S_ISLNK(one.mode) != 0;
  42                 entry->next = NULL;
  43
  44                 *list_p = entry;
  45                 list_p = &entry->next;
  46         }
  47         return ret;
  48 }
  49
  50 static int entcmp(const char *name1, int dir1, const char *name2, int dir2)
  51 {
  52         int len1 = strlen(name1);
  53         int len2 = strlen(name2);
  54         int len = len1 < len2 ? len1 : len2;
  55         int ret = memcmp(name1, name2, len);
  56         unsigned char c1, c2;
  57         if (ret)
  58                 return ret;
  59         c1 = name1[len];
  60         c2 = name2[len];
  61         if (!c1 && dir1)
  62                 c1 = '/';
  63         if (!c2 && dir2)
  64                 c2 = '/';
  65         ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
  66         if (c1 && c2 && !ret)
  67                 ret = len1 - len2;
  68         return ret;
  69 }
  70
  71 static int unpack_trees_rec(struct tree_entry_list **posns, int len,
  72                             const char *base, struct unpack_trees_options *o,
  73                             int *indpos,
  74                             struct tree_entry_list *df_conflict_list)
  75 {
  76         int baselen = strlen(base);
  77         int src_size = len + 1;
  78         int i_stk = i_stk;
  79         int retval = 0;
  80
  81         if (o->dir)
  82                 i_stk = push_exclude_per_directory(o->dir, base, strlen(base));
  83
  84         do {
  85                 int i;
  86                 const char *first;
  87                 int firstdir = 0;
  88                 int pathlen;
  89                 unsigned ce_size;
  90                 struct tree_entry_list **subposns;
  91                 struct cache_entry **src;
  92                 int any_files = 0;
  93                 int any_dirs = 0;
  94                 char *cache_name;
  95                 int ce_stage;
  96
  97                 /* Find the first name in the input. */
  98
  99                 first = NULL;
 100                 cache_name = NULL;
 101
 102                 /* Check the cache */
 103                 if (o->merge && *indpos < active_nr) {
 104                         /* This is a bit tricky: */
 105                         /* If the index has a subdirectory (with
 106                          * contents) as the first name, it'll get a
 107                          * filename like "foo/bar". But that's after
 108                          * "foo", so the entry in trees will get
 109                          * handled first, at which point we'll go into
 110                          * "foo", and deal with "bar" from the index,
 111                          * because the base will be "foo/". The only
 112                          * way we can actually have "foo/bar" first of
 113                          * all the things is if the trees don't
 114                          * contain "foo" at all, in which case we'll
 115                          * handle "foo/bar" without going into the
 116                          * directory, but that's fine (and will return
 117                          * an error anyway, with the added unknown
 118                          * file case.
 119                          */
 120
 121                         cache_name = active_cache[*indpos]->name;
 122                         if (strlen(cache_name) > baselen &&
 123                             !memcmp(cache_name, base, baselen)) {
 124                                 cache_name += baselen;
 125                                 first = cache_name;
 126                         } else {
 127                                 cache_name = NULL;
 128                         }
 129                 }
 130
 131 #if DBRT_DEBUG > 1
 132                 if (first)
 133                         printf("index %s\n", first);
 134 #endif
 135                 for (i = 0; i < len; i++) {
 136                         if (!posns[i] || posns[i] == df_conflict_list)
 137                                 continue;
 138 #if DBRT_DEBUG > 1
 139                         printf("%d %s\n", i + 1, posns[i]->name);
 140 #endif
 141                         if (!first || entcmp(first, firstdir,
 142                                              posns[i]->name,
 143                                              posns[i]->directory) > 0) {
 144                                 first = posns[i]->name;
 145                                 firstdir = posns[i]->directory;
 146                         }
 147                 }
 148                 /* No name means we're done */
 149                 if (!first)
 150                         goto leave_directory;
 151
 152                 pathlen = strlen(first);
 153                 ce_size = cache_entry_size(baselen + pathlen);
 154
 155                 src = xcalloc(src_size, sizeof(struct cache_entry *));
 156
 157                 subposns = xcalloc(len, sizeof(struct tree_list_entry *));
 158
 159                 if (cache_name && !strcmp(cache_name, first)) {
 160                         any_files = 1;
 161                         src[0] = active_cache[*indpos];
 162                         remove_cache_entry_at(*indpos);
 163                 }
 164
 165                 for (i = 0; i < len; i++) {
 166                         struct cache_entry *ce;
 167
 168                         if (!posns[i] ||
 169                             (posns[i] != df_conflict_list &&
 170                              strcmp(first, posns[i]->name))) {
 171                                 continue;
 172                         }
 173
 174                         if (posns[i] == df_conflict_list) {
 175                                 src[i + o->merge] = o->df_conflict_entry;
 176                                 continue;
 177                         }
 178
 179                         if (posns[i]->directory) {
 180                                 struct tree *tree = lookup_tree(posns[i]->sha1);
 181                                 any_dirs = 1;
 182                                 parse_tree(tree);
 183                                 subposns[i] = create_tree_entry_list(tree);
 184                                 posns[i] = posns[i]->next;
 185                                 src[i + o->merge] = o->df_conflict_entry;
 186                                 continue;
 187                         }
 188
 189                         if (!o->merge)
 190                                 ce_stage = 0;
 191                         else if (i + 1 < o->head_idx)
 192                                 ce_stage = 1;
 193                         else if (i + 1 > o->head_idx)
 194                                 ce_stage = 3;
 195                         else
 196                                 ce_stage = 2;
 197
 198                         ce = xcalloc(1, ce_size);
 199                         ce->ce_mode = create_ce_mode(posns[i]->mode);
 200                         ce->ce_flags = create_ce_flags(baselen + pathlen,
 201                                                        ce_stage);
 202                         memcpy(ce->name, base, baselen);
 203                         memcpy(ce->name + baselen, first, pathlen + 1);
 204
 205                         any_files = 1;
 206
 207                         hashcpy(ce->sha1, posns[i]->sha1);
 208                         src[i + o->merge] = ce;
 209                         subposns[i] = df_conflict_list;
 210                         posns[i] = posns[i]->next;
 211                 }
 212                 if (any_files) {
 213                         if (o->merge) {
 214                                 int ret;
 215
 216 #if DBRT_DEBUG > 1
 217                                 printf("%s:\n", first);
 218                                 for (i = 0; i < src_size; i++) {
 219                                         printf(" %d ", i);
 220                                         if (src[i])
 221                                                 printf("%s\n", sha1_to_hex(src[i]->sha1));
 222                                         else
 223                                                 printf("\n");
 224                                 }
 225 #endif
 226                                 ret = o->fn(src, o);
 227
 228 #if DBRT_DEBUG > 1
 229                                 printf("Added %d entries\n", ret);
 230 #endif
 231                                 *indpos += ret;
 232                         } else {
 233                                 for (i = 0; i < src_size; i++) {
 234                                         if (src[i]) {
 235                                                 add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
 236                                         }
 237                                 }
 238                         }
 239                 }
 240                 if (any_dirs) {
 241                         char *newbase = xmalloc(baselen + 2 + pathlen);
 242                         memcpy(newbase, base, baselen);
 243                         memcpy(newbase + baselen, first, pathlen);
 244                         newbase[baselen + pathlen] = '/';
 245                         newbase[baselen + pathlen + 1] = '\0';
 246                         if (unpack_trees_rec(subposns, len, newbase, o,
 247                                              indpos, df_conflict_list)) {
 248                                 retval = -1;
 249                                 goto leave_directory;
 250                         }
 251                         free(newbase);
 252                 }
 253                 free(subposns);
 254                 free(src);
 255         } while (1);
 256
 257  leave_directory:
 258         if (o->dir)
 259                 pop_exclude_per_directory(o->dir, i_stk);
 260         return retval;
 261 }
 262
 263 /* Unlink the last component and attempt to remove leading
 264  * directories, in case this unlink is the removal of the
 265  * last entry in the directory -- empty directories are removed.
 266  */
 267 static void unlink_entry(char *name)
 268 {
 269         char *cp, *prev;
 270
 271         if (unlink(name))
 272                 return;
 273         prev = NULL;
 274         while (1) {
 275                 int status;
 276                 cp = strrchr(name, '/');
 277                 if (prev)
 278                         *prev = '/';
 279                 if (!cp)
 280                         break;
 281
 282                 *cp = 0;
 283                 status = rmdir(name);
 284                 if (status) {
 285                         *cp = '/';
 286                         break;
 287                 }
 288                 prev = cp;
 289         }
 290 }
 291
 292 static volatile sig_atomic_t progress_update;
 293
 294 static void progress_interval(int signum)
 295 {
 296         progress_update = 1;
 297 }
 298
 299 static void setup_progress_signal(void)
 300 {
 301         struct sigaction sa;
 302         struct itimerval v;
 303
 304         memset(&sa, 0, sizeof(sa));
 305         sa.sa_handler = progress_interval;
 306         sigemptyset(&sa.sa_mask);
 307         sa.sa_flags = SA_RESTART;
 308         sigaction(SIGALRM, &sa, NULL);
 309
 310         v.it_interval.tv_sec = 1;
 311         v.it_interval.tv_usec = 0;
 312         v.it_value = v.it_interval;
 313         setitimer(ITIMER_REAL, &v, NULL);
 314 }
 315
 316 static struct checkout state;
 317 static void check_updates(struct cache_entry **src, int nr,
 318                 struct unpack_trees_options *o)
 319 {
 320         unsigned short mask = htons(CE_UPDATE);
 321         unsigned last_percent = 200, cnt = 0, total = 0;
 322
 323         if (o->update && o->verbose_update) {
 324                 for (total = cnt = 0; cnt < nr; cnt++) {
 325                         struct cache_entry *ce = src[cnt];
 326                         if (!ce->ce_mode || ce->ce_flags & mask)
 327                                 total++;
 328                 }
 329
 330                 /* Don't bother doing this for very small updates */
 331                 if (total < 250)
 332                         total = 0;
 333
 334                 if (total) {
 335                         fprintf(stderr, "Checking files out...\n");
 336                         setup_progress_signal();
 337                         progress_update = 1;
 338                 }
 339                 cnt = 0;
 340         }
 341
 342         while (nr--) {
 343                 struct cache_entry *ce = *src++;
 344
 345                 if (total) {
 346                         if (!ce->ce_mode || ce->ce_flags & mask) {
 347                                 unsigned percent;
 348                                 cnt++;
 349                                 percent = (cnt * 100) / total;
 350                                 if (percent != last_percent ||
 351                                     progress_update) {
 352                                         fprintf(stderr, "%4u%% (%u/%u) done\r",
 353                                                 percent, cnt, total);
 354                                         last_percent = percent;
 355                                         progress_update = 0;
 356                                 }
 357                         }
 358                 }
 359                 if (!ce->ce_mode) {
 360                         if (o->update)
 361                                 unlink_entry(ce->name);
 362                         continue;
 363                 }
 364                 if (ce->ce_flags & mask) {
 365                         ce->ce_flags &= ~mask;
 366                         if (o->update)
 367                                 checkout_entry(ce, &state, NULL);
 368                 }
 369         }
 370         if (total) {
 371                 signal(SIGALRM, SIG_IGN);
 372                 fputc('\n', stderr);
 373         }
 374 }
 375
 376 int unpack_trees(struct object_list *trees, struct unpack_trees_options *o)
 377 {
 378         int indpos = 0;
 379         unsigned len = object_list_length(trees);
 380         struct tree_entry_list **posns;
 381         int i;
 382         struct object_list *posn = trees;
 383         struct tree_entry_list df_conflict_list;
 384         static struct cache_entry *dfc;
 385
 386         memset(&df_conflict_list, 0, sizeof(df_conflict_list));
 387         df_conflict_list.next = &df_conflict_list;
 388         memset(&state, 0, sizeof(state));
 389         state.base_dir = "";
 390         state.force = 1;
 391         state.quiet = 1;
 392         state.refresh_cache = 1;
 393
 394         o->merge_size = len;
 395
 396         if (!dfc)
 397                 dfc = xcalloc(1, sizeof(struct cache_entry) + 1);
 398         o->df_conflict_entry = dfc;
 399
 400         if (len) {
 401                 posns = xmalloc(len * sizeof(struct tree_entry_list *));
 402                 for (i = 0; i < len; i++) {
 403                         posns[i] = create_tree_entry_list((struct tree *) posn->item);
 404                         posn = posn->next;
 405                 }
 406                 if (unpack_trees_rec(posns, len, o->prefix ? o->prefix : "",
 407                                      o, &indpos, &df_conflict_list))
 408                         return -1;
 409         }
 410
 411         if (o->trivial_merges_only && o->nontrivial_merge)
 412                 die("Merge requires file-level merging");
 413
 414         check_updates(active_cache, active_nr, o);
 415         return 0;
 416 }
 417
 418 /* Here come the merge functions */
 419
 420 static void reject_merge(struct cache_entry *ce)
 421 {
 422         die("Entry '%s' would be overwritten by merge. Cannot merge.",
 423             ce->name);
 424 }
 425
 426 static int same(struct cache_entry *a, struct cache_entry *b)
 427 {
 428         if (!!a != !!b)
 429                 return 0;
 430         if (!a && !b)
 431                 return 1;
 432         return a->ce_mode == b->ce_mode &&
 433                !hashcmp(a->sha1, b->sha1);
 434 }
 435
 436
 437 /*
 438  * When a CE gets turned into an unmerged entry, we
 439  * want it to be up-to-date
 440  */
 441 static void verify_uptodate(struct cache_entry *ce,
 442                 struct unpack_trees_options *o)
 443 {
 444         struct stat st;
 445
 446         if (o->index_only || o->reset)
 447                 return;
 448
 449         if (!lstat(ce->name, &st)) {
 450                 unsigned changed = ce_match_stat(ce, &st, 1);
 451                 if (!changed)
 452                         return;
 453                 errno = 0;
 454         }
 455         if (o->reset) {
 456                 ce->ce_flags |= htons(CE_UPDATE);
 457                 return;
 458         }
 459         if (errno == ENOENT)
 460                 return;
 461         die("Entry '%s' not uptodate. Cannot merge.", ce->name);
 462 }
 463
 464 static void invalidate_ce_path(struct cache_entry *ce)
 465 {
 466         if (ce)
 467                 cache_tree_invalidate_path(active_cache_tree, ce->name);
 468 }
 469
 470 /*
 471  * We do not want to remove or overwrite a working tree file that
 472  * is not tracked, unless it is ignored.
 473  */
 474 static void verify_absent(const char *path, const char *action,
 475                 struct unpack_trees_options *o)
 476 {
 477         struct stat st;
 478
 479         if (o->index_only || o->reset || !o->update)
 480                 return;
 481         if (!lstat(path, &st) && !(o->dir && excluded(o->dir, path)))
 482                 die("Untracked working tree file '%s' "
 483                     "would be %s by merge.", path, action);
 484 }
 485
 486 static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 487                 struct unpack_trees_options *o)
 488 {
 489         merge->ce_flags |= htons(CE_UPDATE);
 490         if (old) {
 491                 /*
 492                  * See if we can re-use the old CE directly?
 493                  * That way we get the uptodate stat info.
 494                  *
 495                  * This also removes the UPDATE flag on
 496                  * a match.
 497                  */
 498                 if (same(old, merge)) {
 499                         *merge = *old;
 500                 } else {
 501                         verify_uptodate(old, o);
 502                         invalidate_ce_path(old);
 503                 }
 504         }
 505         else {
 506                 verify_absent(merge->name, "overwritten", o);
 507                 invalidate_ce_path(merge);
 508         }
 509
 510         merge->ce_flags &= ~htons(CE_STAGEMASK);
 511         add_cache_entry(merge, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
 512         return 1;
 513 }
 514
 515 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
 516                 struct unpack_trees_options *o)
 517 {
 518         if (old)
 519                 verify_uptodate(old, o);
 520         else
 521                 verify_absent(ce->name, "removed", o);
 522         ce->ce_mode = 0;
 523         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
 524         invalidate_ce_path(ce);
 525         return 1;
 526 }
 527
 528 static int keep_entry(struct cache_entry *ce)
 529 {
 530         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
 531         return 1;
 532 }
 533
 534 #if DBRT_DEBUG
 535 static void show_stage_entry(FILE *o,
 536                              const char *label, const struct cache_entry *ce)
 537 {
 538         if (!ce)
 539                 fprintf(o, "%s (missing)\n", label);
 540         else
 541                 fprintf(o, "%s%06o %s %d\t%s\n",
 542                         label,
 543                         ntohl(ce->ce_mode),
 544                         sha1_to_hex(ce->sha1),
 545                         ce_stage(ce),
 546                         ce->name);
 547 }
 548 #endif
 549
 550 int threeway_merge(struct cache_entry **stages,
 551                 struct unpack_trees_options *o)
 552 {
 553         struct cache_entry *index;
 554         struct cache_entry *head;
 555         struct cache_entry *remote = stages[o->head_idx + 1];
 556         int count;
 557         int head_match = 0;
 558         int remote_match = 0;
 559         const char *path = NULL;
 560
 561         int df_conflict_head = 0;
 562         int df_conflict_remote = 0;
 563
 564         int any_anc_missing = 0;
 565         int no_anc_exists = 1;
 566         int i;
 567
 568         for (i = 1; i < o->head_idx; i++) {
 569                 if (!stages[i])
 570                         any_anc_missing = 1;
 571                 else {
 572                         if (!path)
 573                                 path = stages[i]->name;
 574                         no_anc_exists = 0;
 575                 }
 576         }
 577
 578         index = stages[0];
 579         head = stages[o->head_idx];
 580
 581         if (head == o->df_conflict_entry) {
 582                 df_conflict_head = 1;
 583                 head = NULL;
 584         }
 585
 586         if (remote == o->df_conflict_entry) {
 587                 df_conflict_remote = 1;
 588                 remote = NULL;
 589         }
 590
 591         if (!path && index)
 592                 path = index->name;
 593         if (!path && head)
 594                 path = head->name;
 595         if (!path && remote)
 596                 path = remote->name;
 597
 598         /* First, if there's a #16 situation, note that to prevent #13
 599          * and #14.
 600          */
 601         if (!same(remote, head)) {
 602                 for (i = 1; i < o->head_idx; i++) {
 603                         if (same(stages[i], head)) {
 604                                 head_match = i;
 605                         }
 606                         if (same(stages[i], remote)) {
 607                                 remote_match = i;
 608                         }
 609                 }
 610         }
 611
 612         /* We start with cases where the index is allowed to match
 613          * something other than the head: #14(ALT) and #2ALT, where it
 614          * is permitted to match the result instead.
 615          */
 616         /* #14, #14ALT, #2ALT */
 617         if (remote && !df_conflict_head && head_match && !remote_match) {
 618                 if (index && !same(index, remote) && !same(index, head))
 619                         reject_merge(index);
 620                 return merged_entry(remote, index, o);
 621         }
 622         /*
 623          * If we have an entry in the index cache, then we want to
 624          * make sure that it matches head.
 625          */
 626         if (index && !same(index, head)) {
 627                 reject_merge(index);
 628         }
 629
 630         if (head) {
 631                 /* #5ALT, #15 */
 632                 if (same(head, remote))
 633                         return merged_entry(head, index, o);
 634                 /* #13, #3ALT */
 635                 if (!df_conflict_remote && remote_match && !head_match)
 636                         return merged_entry(head, index, o);
 637         }
 638
 639         /* #1 */
 640         if (!head && !remote && any_anc_missing)
 641                 return 0;
 642
 643         /* Under the new "aggressive" rule, we resolve mostly trivial
 644          * cases that we historically had git-merge-one-file resolve.
 645          */
 646         if (o->aggressive) {
 647                 int head_deleted = !head && !df_conflict_head;
 648                 int remote_deleted = !remote && !df_conflict_remote;
 649                 /*
 650                  * Deleted in both.
 651                  * Deleted in one and unchanged in the other.
 652                  */
 653                 if ((head_deleted && remote_deleted) ||
 654                     (head_deleted && remote && remote_match) ||
 655                     (remote_deleted && head && head_match)) {
 656                         if (index)
 657                                 return deleted_entry(index, index, o);
 658                         else if (path && !head_deleted)
 659                                 verify_absent(path, "removed", o);
 660                         return 0;
 661                 }
 662                 /*
 663                  * Added in both, identically.
 664                  */
 665                 if (no_anc_exists && head && remote && same(head, remote))
 666                         return merged_entry(head, index, o);
 667
 668         }
 669
 670         /* Below are "no merge" cases, which require that the index be
 671          * up-to-date to avoid the files getting overwritten with
 672          * conflict resolution files.
 673          */
 674         if (index) {
 675                 verify_uptodate(index, o);
 676         }
 677
 678         o->nontrivial_merge = 1;
 679
 680         /* #2, #3, #4, #6, #7, #9, #11. */
 681         count = 0;
 682         if (!head_match || !remote_match) {
 683                 for (i = 1; i < o->head_idx; i++) {
 684                         if (stages[i]) {
 685                                 keep_entry(stages[i]);
 686                                 count++;
 687                                 break;
 688                         }
 689                 }
 690         }
 691 #if DBRT_DEBUG
 692         else {
 693                 fprintf(stderr, "read-tree: warning #16 detected\n");
 694                 show_stage_entry(stderr, "head   ", stages[head_match]);
 695                 show_stage_entry(stderr, "remote ", stages[remote_match]);
 696         }
 697 #endif
 698         if (head) { count += keep_entry(head); }
 699         if (remote) { count += keep_entry(remote); }
 700         return count;
 701 }
 702
 703 /*
 704  * Two-way merge.
 705  *
 706  * The rule is to "carry forward" what is in the index without losing
 707  * information across a "fast forward", favoring a successful merge
 708  * over a merge failure when it makes sense.  For details of the
 709  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
 710  *
 711  */
 712 int twoway_merge(struct cache_entry **src,
 713                 struct unpack_trees_options *o)
 714 {
 715         struct cache_entry *current = src[0];
 716         struct cache_entry *oldtree = src[1], *newtree = src[2];
 717
 718         if (o->merge_size != 2)
 719                 return error("Cannot do a twoway merge of %d trees",
 720                              o->merge_size);
 721
 722         if (current) {
 723                 if ((!oldtree && !newtree) || /* 4 and 5 */
 724                     (!oldtree && newtree &&
 725                      same(current, newtree)) || /* 6 and 7 */
 726                     (oldtree && newtree &&
 727                      same(oldtree, newtree)) || /* 14 and 15 */
 728                     (oldtree && newtree &&
 729                      !same(oldtree, newtree) && /* 18 and 19*/
 730                      same(current, newtree))) {
 731                         return keep_entry(current);
 732                 }
 733                 else if (oldtree && !newtree && same(current, oldtree)) {
 734                         /* 10 or 11 */
 735                         return deleted_entry(oldtree, current, o);
 736                 }
 737                 else if (oldtree && newtree &&
 738                          same(current, oldtree) && !same(current, newtree)) {
 739                         /* 20 or 21 */
 740                         return merged_entry(newtree, current, o);
 741                 }
 742                 else {
 743                         /* all other failures */
 744                         if (oldtree)
 745                                 reject_merge(oldtree);
 746                         if (current)
 747                                 reject_merge(current);
 748                         if (newtree)
 749                                 reject_merge(newtree);
 750                         return -1;
 751                 }
 752         }
 753         else if (newtree)
 754                 return merged_entry(newtree, current, o);
 755         else
 756                 return deleted_entry(oldtree, current, o);
 757 }
 758
 759 /*
 760  * Bind merge.
 761  *
 762  * Keep the index entries at stage0, collapse stage1 but make sure
 763  * stage0 does not have anything there.
 764  */
 765 int bind_merge(struct cache_entry **src,
 766                 struct unpack_trees_options *o)
 767 {
 768         struct cache_entry *old = src[0];
 769         struct cache_entry *a = src[1];
 770
 771         if (o->merge_size != 1)
 772                 return error("Cannot do a bind merge of %d trees\n",
 773                              o->merge_size);
 774         if (a && old)
 775                 die("Entry '%s' overlaps.  Cannot bind.", a->name);
 776         if (!a)
 777                 return keep_entry(old);
 778         else
 779                 return merged_entry(a, NULL, o);
 780 }
 781
 782 /*
 783  * One-way merge.
 784  *
 785  * The rule is:
 786  * - take the stat information from stage0, take the data from stage1
 787  */
 788 int oneway_merge(struct cache_entry **src,
 789                 struct unpack_trees_options *o)
 790 {
 791         struct cache_entry *old = src[0];
 792         struct cache_entry *a = src[1];
 793
 794         if (o->merge_size != 1)
 795                 return error("Cannot do a oneway merge of %d trees",
 796                              o->merge_size);
 797
 798         if (!a)
 799                 return deleted_entry(old, old, o);
 800         if (old && same(old, a)) {
 801                 if (o->reset) {
 802                         struct stat st;
 803                         if (lstat(old->name, &st) ||
 804                             ce_match_stat(old, &st, 1))
 805                                 old->ce_flags |= htons(CE_UPDATE);
 806                 }
 807                 return keep_entry(old);
 808         }
 809         return merged_entry(a, old, o);
 810 }