unpack-trees.c

   1 #include <signal.h>
   2 #include <sys/time.h>
   3 #include "cache.h"
   4 #include "dir.h"
   5 #include "tree.h"
   6 #include "tree-walk.h"
   7 #include "cache-tree.h"
   8 #include "unpack-trees.h"
   9
  10 #define DBRT_DEBUG 1
  11
  12 struct tree_entry_list {
  13         struct tree_entry_list *next;
  14         unsigned directory : 1;
  15         unsigned executable : 1;
  16         unsigned symlink : 1;
  17         unsigned int mode;
  18         const char *name;
  19         const unsigned char *sha1;
  20 };
  21
  22 static struct tree_entry_list *create_tree_entry_list(struct tree *tree)
  23 {
  24         struct tree_desc desc;
  25         struct name_entry one;
  26         struct tree_entry_list *ret = NULL;
  27         struct tree_entry_list **list_p = &ret;
  28
  29         if (!tree->object.parsed)
  30                 parse_tree(tree);
  31
  32         desc.buf = tree->buffer;
  33         desc.size = tree->size;
  34
  35         while (tree_entry(&desc, &one)) {
  36                 struct tree_entry_list *entry;
  37
  38                 entry = xmalloc(sizeof(struct tree_entry_list));
  39                 entry->name = one.path;
  40                 entry->sha1 = one.sha1;
  41                 entry->mode = one.mode;
  42                 entry->directory = S_ISDIR(one.mode) != 0;
  43                 entry->executable = (one.mode & S_IXUSR) != 0;
  44                 entry->symlink = S_ISLNK(one.mode) != 0;
  45                 entry->next = NULL;
  46
  47                 *list_p = entry;
  48                 list_p = &entry->next;
  49         }
  50         return ret;
  51 }
  52
  53 static int entcmp(const char *name1, int dir1, const char *name2, int dir2)
  54 {
  55         int len1 = strlen(name1);
  56         int len2 = strlen(name2);
  57         int len = len1 < len2 ? len1 : len2;
  58         int ret = memcmp(name1, name2, len);
  59         unsigned char c1, c2;
  60         if (ret)
  61                 return ret;
  62         c1 = name1[len];
  63         c2 = name2[len];
  64         if (!c1 && dir1)
  65                 c1 = '/';
  66         if (!c2 && dir2)
  67                 c2 = '/';
  68         ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
  69         if (c1 && c2 && !ret)
  70                 ret = len1 - len2;
  71         return ret;
  72 }
  73
  74 static int unpack_trees_rec(struct tree_entry_list **posns, int len,
  75                             const char *base, struct unpack_trees_options *o,
  76                             int *indpos,
  77                             struct tree_entry_list *df_conflict_list)
  78 {
  79         int baselen = strlen(base);
  80         int src_size = len + 1;
  81         int i_stk = i_stk;
  82         int retval = 0;
  83
  84         if (o->dir)
  85                 i_stk = push_exclude_per_directory(o->dir, base, strlen(base));
  86
  87         do {
  88                 int i;
  89                 const char *first;
  90                 int firstdir = 0;
  91                 int pathlen;
  92                 unsigned ce_size;
  93                 struct tree_entry_list **subposns;
  94                 struct cache_entry **src;
  95                 int any_files = 0;
  96                 int any_dirs = 0;
  97                 char *cache_name;
  98                 int ce_stage;
  99
 100                 /* Find the first name in the input. */
 101
 102                 first = NULL;
 103                 cache_name = NULL;
 104
 105                 /* Check the cache */
 106                 if (o->merge && *indpos < active_nr) {
 107                         /* This is a bit tricky: */
 108                         /* If the index has a subdirectory (with
 109                          * contents) as the first name, it'll get a
 110                          * filename like "foo/bar". But that's after
 111                          * "foo", so the entry in trees will get
 112                          * handled first, at which point we'll go into
 113                          * "foo", and deal with "bar" from the index,
 114                          * because the base will be "foo/". The only
 115                          * way we can actually have "foo/bar" first of
 116                          * all the things is if the trees don't
 117                          * contain "foo" at all, in which case we'll
 118                          * handle "foo/bar" without going into the
 119                          * directory, but that's fine (and will return
 120                          * an error anyway, with the added unknown
 121                          * file case.
 122                          */
 123
 124                         cache_name = active_cache[*indpos]->name;
 125                         if (strlen(cache_name) > baselen &&
 126                             !memcmp(cache_name, base, baselen)) {
 127                                 cache_name += baselen;
 128                                 first = cache_name;
 129                         } else {
 130                                 cache_name = NULL;
 131                         }
 132                 }
 133
 134 #if DBRT_DEBUG > 1
 135                 if (first)
 136                         printf("index %s\n", first);
 137 #endif
 138                 for (i = 0; i < len; i++) {
 139                         if (!posns[i] || posns[i] == df_conflict_list)
 140                                 continue;
 141 #if DBRT_DEBUG > 1
 142                         printf("%d %s\n", i + 1, posns[i]->name);
 143 #endif
 144                         if (!first || entcmp(first, firstdir,
 145                                              posns[i]->name,
 146                                              posns[i]->directory) > 0) {
 147                                 first = posns[i]->name;
 148                                 firstdir = posns[i]->directory;
 149                         }
 150                 }
 151                 /* No name means we're done */
 152                 if (!first)
 153                         goto leave_directory;
 154
 155                 pathlen = strlen(first);
 156                 ce_size = cache_entry_size(baselen + pathlen);
 157
 158                 src = xcalloc(src_size, sizeof(struct cache_entry *));
 159
 160                 subposns = xcalloc(len, sizeof(struct tree_list_entry *));
 161
 162                 if (cache_name && !strcmp(cache_name, first)) {
 163                         any_files = 1;
 164                         src[0] = active_cache[*indpos];
 165                         remove_cache_entry_at(*indpos);
 166                 }
 167
 168                 for (i = 0; i < len; i++) {
 169                         struct cache_entry *ce;
 170
 171                         if (!posns[i] ||
 172                             (posns[i] != df_conflict_list &&
 173                              strcmp(first, posns[i]->name))) {
 174                                 continue;
 175                         }
 176
 177                         if (posns[i] == df_conflict_list) {
 178                                 src[i + o->merge] = o->df_conflict_entry;
 179                                 continue;
 180                         }
 181
 182                         if (posns[i]->directory) {
 183                                 struct tree *tree = lookup_tree(posns[i]->sha1);
 184                                 any_dirs = 1;
 185                                 parse_tree(tree);
 186                                 subposns[i] = create_tree_entry_list(tree);
 187                                 posns[i] = posns[i]->next;
 188                                 src[i + o->merge] = o->df_conflict_entry;
 189                                 continue;
 190                         }
 191
 192                         if (!o->merge)
 193                                 ce_stage = 0;
 194                         else if (i + 1 < o->head_idx)
 195                                 ce_stage = 1;
 196                         else if (i + 1 > o->head_idx)
 197                                 ce_stage = 3;
 198                         else
 199                                 ce_stage = 2;
 200
 201                         ce = xcalloc(1, ce_size);
 202                         ce->ce_mode = create_ce_mode(posns[i]->mode);
 203                         ce->ce_flags = create_ce_flags(baselen + pathlen,
 204                                                        ce_stage);
 205                         memcpy(ce->name, base, baselen);
 206                         memcpy(ce->name + baselen, first, pathlen + 1);
 207
 208                         any_files = 1;
 209
 210                         hashcpy(ce->sha1, posns[i]->sha1);
 211                         src[i + o->merge] = ce;
 212                         subposns[i] = df_conflict_list;
 213                         posns[i] = posns[i]->next;
 214                 }
 215                 if (any_files) {
 216                         if (o->merge) {
 217                                 int ret;
 218
 219 #if DBRT_DEBUG > 1
 220                                 printf("%s:\n", first);
 221                                 for (i = 0; i < src_size; i++) {
 222                                         printf(" %d ", i);
 223                                         if (src[i])
 224                                                 printf("%s\n", sha1_to_hex(src[i]->sha1));
 225                                         else
 226                                                 printf("\n");
 227                                 }
 228 #endif
 229                                 ret = o->fn(src, o);
 230
 231 #if DBRT_DEBUG > 1
 232                                 printf("Added %d entries\n", ret);
 233 #endif
 234                                 *indpos += ret;
 235                         } else {
 236                                 for (i = 0; i < src_size; i++) {
 237                                         if (src[i]) {
 238                                                 add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
 239                                         }
 240                                 }
 241                         }
 242                 }
 243                 if (any_dirs) {
 244                         char *newbase = xmalloc(baselen + 2 + pathlen);
 245                         memcpy(newbase, base, baselen);
 246                         memcpy(newbase + baselen, first, pathlen);
 247                         newbase[baselen + pathlen] = '/';
 248                         newbase[baselen + pathlen + 1] = '\0';
 249                         if (unpack_trees_rec(subposns, len, newbase, o,
 250                                              indpos, df_conflict_list)) {
 251                                 retval = -1;
 252                                 goto leave_directory;
 253                         }
 254                         free(newbase);
 255                 }
 256                 free(subposns);
 257                 free(src);
 258         } while (1);
 259
 260  leave_directory:
 261         if (o->dir)
 262                 pop_exclude_per_directory(o->dir, i_stk);
 263         return retval;
 264 }
 265
 266 /* Unlink the last component and attempt to remove leading
 267  * directories, in case this unlink is the removal of the
 268  * last entry in the directory -- empty directories are removed.
 269  */
 270 static void unlink_entry(char *name)
 271 {
 272         char *cp, *prev;
 273
 274         if (unlink(name))
 275                 return;
 276         prev = NULL;
 277         while (1) {
 278                 int status;
 279                 cp = strrchr(name, '/');
 280                 if (prev)
 281                         *prev = '/';
 282                 if (!cp)
 283                         break;
 284
 285                 *cp = 0;
 286                 status = rmdir(name);
 287                 if (status) {
 288                         *cp = '/';
 289                         break;
 290                 }
 291                 prev = cp;
 292         }
 293 }
 294
 295 static volatile sig_atomic_t progress_update;
 296
 297 static void progress_interval(int signum)
 298 {
 299         progress_update = 1;
 300 }
 301
 302 static void setup_progress_signal(void)
 303 {
 304         struct sigaction sa;
 305         struct itimerval v;
 306
 307         memset(&sa, 0, sizeof(sa));
 308         sa.sa_handler = progress_interval;
 309         sigemptyset(&sa.sa_mask);
 310         sa.sa_flags = SA_RESTART;
 311         sigaction(SIGALRM, &sa, NULL);
 312
 313         v.it_interval.tv_sec = 1;
 314         v.it_interval.tv_usec = 0;
 315         v.it_value = v.it_interval;
 316         setitimer(ITIMER_REAL, &v, NULL);
 317 }
 318
 319 static struct checkout state;
 320 static void check_updates(struct cache_entry **src, int nr,
 321                 struct unpack_trees_options *o)
 322 {
 323         unsigned short mask = htons(CE_UPDATE);
 324         unsigned last_percent = 200, cnt = 0, total = 0;
 325
 326         if (o->update && o->verbose_update) {
 327                 for (total = cnt = 0; cnt < nr; cnt++) {
 328                         struct cache_entry *ce = src[cnt];
 329                         if (!ce->ce_mode || ce->ce_flags & mask)
 330                                 total++;
 331                 }
 332
 333                 /* Don't bother doing this for very small updates */
 334                 if (total < 250)
 335                         total = 0;
 336
 337                 if (total) {
 338                         fprintf(stderr, "Checking files out...\n");
 339                         setup_progress_signal();
 340                         progress_update = 1;
 341                 }
 342                 cnt = 0;
 343         }
 344
 345         while (nr--) {
 346                 struct cache_entry *ce = *src++;
 347
 348                 if (total) {
 349                         if (!ce->ce_mode || ce->ce_flags & mask) {
 350                                 unsigned percent;
 351                                 cnt++;
 352                                 percent = (cnt * 100) / total;
 353                                 if (percent != last_percent ||
 354                                     progress_update) {
 355                                         fprintf(stderr, "%4u%% (%u/%u) done\r",
 356                                                 percent, cnt, total);
 357                                         last_percent = percent;
 358                                         progress_update = 0;
 359                                 }
 360                         }
 361                 }
 362                 if (!ce->ce_mode) {
 363                         if (o->update)
 364                                 unlink_entry(ce->name);
 365                         continue;
 366                 }
 367                 if (ce->ce_flags & mask) {
 368                         ce->ce_flags &= ~mask;
 369                         if (o->update)
 370                                 checkout_entry(ce, &state, NULL);
 371                 }
 372         }
 373         if (total) {
 374                 signal(SIGALRM, SIG_IGN);
 375                 fputc('\n', stderr);
 376         }
 377 }
 378
 379 int unpack_trees(struct object_list *trees, struct unpack_trees_options *o)
 380 {
 381         int indpos = 0;
 382         unsigned len = object_list_length(trees);
 383         struct tree_entry_list **posns;
 384         int i;
 385         struct object_list *posn = trees;
 386         struct tree_entry_list df_conflict_list;
 387         struct cache_entry df_conflict_entry;
 388
 389         memset(&df_conflict_list, 0, sizeof(df_conflict_list));
 390         df_conflict_list.next = &df_conflict_list;
 391         memset(&state, 0, sizeof(state));
 392         state.base_dir = "";
 393         state.force = 1;
 394         state.quiet = 1;
 395         state.refresh_cache = 1;
 396
 397         o->merge_size = len;
 398         memset(&df_conflict_entry, 0, sizeof(df_conflict_entry));
 399         o->df_conflict_entry = &df_conflict_entry;
 400
 401         if (len) {
 402                 posns = xmalloc(len * sizeof(struct tree_entry_list *));
 403                 for (i = 0; i < len; i++) {
 404                         posns[i] = create_tree_entry_list((struct tree *) posn->item);
 405                         posn = posn->next;
 406                 }
 407                 if (unpack_trees_rec(posns, len, o->prefix ? o->prefix : "",
 408                                      o, &indpos, &df_conflict_list))
 409                         return -1;
 410         }
 411
 412         if (o->trivial_merges_only && o->nontrivial_merge)
 413                 die("Merge requires file-level merging");
 414
 415         check_updates(active_cache, active_nr, o);
 416         return 0;
 417 }
 418
 419 /* Here come the merge functions */
 420
 421 static void reject_merge(struct cache_entry *ce)
 422 {
 423         die("Entry '%s' would be overwritten by merge. Cannot merge.",
 424             ce->name);
 425 }
 426
 427 static int same(struct cache_entry *a, struct cache_entry *b)
 428 {
 429         if (!!a != !!b)
 430                 return 0;
 431         if (!a && !b)
 432                 return 1;
 433         return a->ce_mode == b->ce_mode &&
 434                !hashcmp(a->sha1, b->sha1);
 435 }
 436
 437
 438 /*
 439  * When a CE gets turned into an unmerged entry, we
 440  * want it to be up-to-date
 441  */
 442 static void verify_uptodate(struct cache_entry *ce,
 443                 struct unpack_trees_options *o)
 444 {
 445         struct stat st;
 446
 447         if (o->index_only || o->reset)
 448                 return;
 449
 450         if (!lstat(ce->name, &st)) {
 451                 unsigned changed = ce_match_stat(ce, &st, 1);
 452                 if (!changed)
 453                         return;
 454                 errno = 0;
 455         }
 456         if (o->reset) {
 457                 ce->ce_flags |= htons(CE_UPDATE);
 458                 return;
 459         }
 460         if (errno == ENOENT)
 461                 return;
 462         die("Entry '%s' not uptodate. Cannot merge.", ce->name);
 463 }
 464
 465 static void invalidate_ce_path(struct cache_entry *ce)
 466 {
 467         if (ce)
 468                 cache_tree_invalidate_path(active_cache_tree, ce->name);
 469 }
 470
 471 /*
 472  * We do not want to remove or overwrite a working tree file that
 473  * is not tracked, unless it is ignored.
 474  */
 475 static void verify_absent(const char *path, const char *action,
 476                 struct unpack_trees_options *o)
 477 {
 478         struct stat st;
 479
 480         if (o->index_only || o->reset || !o->update)
 481                 return;
 482         if (!lstat(path, &st) && !(o->dir && excluded(o->dir, path)))
 483                 die("Untracked working tree file '%s' "
 484                     "would be %s by merge.", path, action);
 485 }
 486
 487 static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 488                 struct unpack_trees_options *o)
 489 {
 490         merge->ce_flags |= htons(CE_UPDATE);
 491         if (old) {
 492                 /*
 493                  * See if we can re-use the old CE directly?
 494                  * That way we get the uptodate stat info.
 495                  *
 496                  * This also removes the UPDATE flag on
 497                  * a match.
 498                  */
 499                 if (same(old, merge)) {
 500                         *merge = *old;
 501                 } else {
 502                         verify_uptodate(old, o);
 503                         invalidate_ce_path(old);
 504                 }
 505         }
 506         else {
 507                 verify_absent(merge->name, "overwritten", o);
 508                 invalidate_ce_path(merge);
 509         }
 510
 511         merge->ce_flags &= ~htons(CE_STAGEMASK);
 512         add_cache_entry(merge, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
 513         return 1;
 514 }
 515
 516 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
 517                 struct unpack_trees_options *o)
 518 {
 519         if (old)
 520                 verify_uptodate(old, o);
 521         else
 522                 verify_absent(ce->name, "removed", o);
 523         ce->ce_mode = 0;
 524         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
 525         invalidate_ce_path(ce);
 526         return 1;
 527 }
 528
 529 static int keep_entry(struct cache_entry *ce)
 530 {
 531         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
 532         return 1;
 533 }
 534
 535 #if DBRT_DEBUG
 536 static void show_stage_entry(FILE *o,
 537                              const char *label, const struct cache_entry *ce)
 538 {
 539         if (!ce)
 540                 fprintf(o, "%s (missing)\n", label);
 541         else
 542                 fprintf(o, "%s%06o %s %d\t%s\n",
 543                         label,
 544                         ntohl(ce->ce_mode),
 545                         sha1_to_hex(ce->sha1),
 546                         ce_stage(ce),
 547                         ce->name);
 548 }
 549 #endif
 550
 551 int threeway_merge(struct cache_entry **stages,
 552                 struct unpack_trees_options *o)
 553 {
 554         struct cache_entry *index;
 555         struct cache_entry *head;
 556         struct cache_entry *remote = stages[o->head_idx + 1];
 557         int count;
 558         int head_match = 0;
 559         int remote_match = 0;
 560         const char *path = NULL;
 561
 562         int df_conflict_head = 0;
 563         int df_conflict_remote = 0;
 564
 565         int any_anc_missing = 0;
 566         int no_anc_exists = 1;
 567         int i;
 568
 569         for (i = 1; i < o->head_idx; i++) {
 570                 if (!stages[i])
 571                         any_anc_missing = 1;
 572                 else {
 573                         if (!path)
 574                                 path = stages[i]->name;
 575                         no_anc_exists = 0;
 576                 }
 577         }
 578
 579         index = stages[0];
 580         head = stages[o->head_idx];
 581
 582         if (head == o->df_conflict_entry) {
 583                 df_conflict_head = 1;
 584                 head = NULL;
 585         }
 586
 587         if (remote == o->df_conflict_entry) {
 588                 df_conflict_remote = 1;
 589                 remote = NULL;
 590         }
 591
 592         if (!path && index)
 593                 path = index->name;
 594         if (!path && head)
 595                 path = head->name;
 596         if (!path && remote)
 597                 path = remote->name;
 598
 599         /* First, if there's a #16 situation, note that to prevent #13
 600          * and #14.
 601          */
 602         if (!same(remote, head)) {
 603                 for (i = 1; i < o->head_idx; i++) {
 604                         if (same(stages[i], head)) {
 605                                 head_match = i;
 606                         }
 607                         if (same(stages[i], remote)) {
 608                                 remote_match = i;
 609                         }
 610                 }
 611         }
 612
 613         /* We start with cases where the index is allowed to match
 614          * something other than the head: #14(ALT) and #2ALT, where it
 615          * is permitted to match the result instead.
 616          */
 617         /* #14, #14ALT, #2ALT */
 618         if (remote && !df_conflict_head && head_match && !remote_match) {
 619                 if (index && !same(index, remote) && !same(index, head))
 620                         reject_merge(index);
 621                 return merged_entry(remote, index, o);
 622         }
 623         /*
 624          * If we have an entry in the index cache, then we want to
 625          * make sure that it matches head.
 626          */
 627         if (index && !same(index, head)) {
 628                 reject_merge(index);
 629         }
 630
 631         if (head) {
 632                 /* #5ALT, #15 */
 633                 if (same(head, remote))
 634                         return merged_entry(head, index, o);
 635                 /* #13, #3ALT */
 636                 if (!df_conflict_remote && remote_match && !head_match)
 637                         return merged_entry(head, index, o);
 638         }
 639
 640         /* #1 */
 641         if (!head && !remote && any_anc_missing)
 642                 return 0;
 643
 644         /* Under the new "aggressive" rule, we resolve mostly trivial
 645          * cases that we historically had git-merge-one-file resolve.
 646          */
 647         if (o->aggressive) {
 648                 int head_deleted = !head && !df_conflict_head;
 649                 int remote_deleted = !remote && !df_conflict_remote;
 650                 /*
 651                  * Deleted in both.
 652                  * Deleted in one and unchanged in the other.
 653                  */
 654                 if ((head_deleted && remote_deleted) ||
 655                     (head_deleted && remote && remote_match) ||
 656                     (remote_deleted && head && head_match)) {
 657                         if (index)
 658                                 return deleted_entry(index, index, o);
 659                         else if (path && !head_deleted)
 660                                 verify_absent(path, "removed", o);
 661                         return 0;
 662                 }
 663                 /*
 664                  * Added in both, identically.
 665                  */
 666                 if (no_anc_exists && head && remote && same(head, remote))
 667                         return merged_entry(head, index, o);
 668
 669         }
 670
 671         /* Below are "no merge" cases, which require that the index be
 672          * up-to-date to avoid the files getting overwritten with
 673          * conflict resolution files.
 674          */
 675         if (index) {
 676                 verify_uptodate(index, o);
 677         }
 678
 679         o->nontrivial_merge = 1;
 680
 681         /* #2, #3, #4, #6, #7, #9, #11. */
 682         count = 0;
 683         if (!head_match || !remote_match) {
 684                 for (i = 1; i < o->head_idx; i++) {
 685                         if (stages[i]) {
 686                                 keep_entry(stages[i]);
 687                                 count++;
 688                                 break;
 689                         }
 690                 }
 691         }
 692 #if DBRT_DEBUG
 693         else {
 694                 fprintf(stderr, "read-tree: warning #16 detected\n");
 695                 show_stage_entry(stderr, "head   ", stages[head_match]);
 696                 show_stage_entry(stderr, "remote ", stages[remote_match]);
 697         }
 698 #endif
 699         if (head) { count += keep_entry(head); }
 700         if (remote) { count += keep_entry(remote); }
 701         return count;
 702 }
 703
 704 /*
 705  * Two-way merge.
 706  *
 707  * The rule is to "carry forward" what is in the index without losing
 708  * information across a "fast forward", favoring a successful merge
 709  * over a merge failure when it makes sense.  For details of the
 710  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
 711  *
 712  */
 713 int twoway_merge(struct cache_entry **src,
 714                 struct unpack_trees_options *o)
 715 {
 716         struct cache_entry *current = src[0];
 717         struct cache_entry *oldtree = src[1], *newtree = src[2];
 718
 719         if (o->merge_size != 2)
 720                 return error("Cannot do a twoway merge of %d trees",
 721                              o->merge_size);
 722
 723         if (current) {
 724                 if ((!oldtree && !newtree) || /* 4 and 5 */
 725                     (!oldtree && newtree &&
 726                      same(current, newtree)) || /* 6 and 7 */
 727                     (oldtree && newtree &&
 728                      same(oldtree, newtree)) || /* 14 and 15 */
 729                     (oldtree && newtree &&
 730                      !same(oldtree, newtree) && /* 18 and 19*/
 731                      same(current, newtree))) {
 732                         return keep_entry(current);
 733                 }
 734                 else if (oldtree && !newtree && same(current, oldtree)) {
 735                         /* 10 or 11 */
 736                         return deleted_entry(oldtree, current, o);
 737                 }
 738                 else if (oldtree && newtree &&
 739                          same(current, oldtree) && !same(current, newtree)) {
 740                         /* 20 or 21 */
 741                         return merged_entry(newtree, current, o);
 742                 }
 743                 else {
 744                         /* all other failures */
 745                         if (oldtree)
 746                                 reject_merge(oldtree);
 747                         if (current)
 748                                 reject_merge(current);
 749                         if (newtree)
 750                                 reject_merge(newtree);
 751                         return -1;
 752                 }
 753         }
 754         else if (newtree)
 755                 return merged_entry(newtree, current, o);
 756         else
 757                 return deleted_entry(oldtree, current, o);
 758 }
 759
 760 /*
 761  * Bind merge.
 762  *
 763  * Keep the index entries at stage0, collapse stage1 but make sure
 764  * stage0 does not have anything there.
 765  */
 766 int bind_merge(struct cache_entry **src,
 767                 struct unpack_trees_options *o)
 768 {
 769         struct cache_entry *old = src[0];
 770         struct cache_entry *a = src[1];
 771
 772         if (o->merge_size != 1)
 773                 return error("Cannot do a bind merge of %d trees\n",
 774                              o->merge_size);
 775         if (a && old)
 776                 die("Entry '%s' overlaps.  Cannot bind.", a->name);
 777         if (!a)
 778                 return keep_entry(old);
 779         else
 780                 return merged_entry(a, NULL, o);
 781 }
 782
 783 /*
 784  * One-way merge.
 785  *
 786  * The rule is:
 787  * - take the stat information from stage0, take the data from stage1
 788  */
 789 int oneway_merge(struct cache_entry **src,
 790                 struct unpack_trees_options *o)
 791 {
 792         struct cache_entry *old = src[0];
 793         struct cache_entry *a = src[1];
 794
 795         if (o->merge_size != 1)
 796                 return error("Cannot do a oneway merge of %d trees",
 797                              o->merge_size);
 798
 799         if (!a)
 800                 return deleted_entry(old, old, o);
 801         if (old && same(old, a)) {
 802                 if (o->reset) {
 803                         struct stat st;
 804                         if (lstat(old->name, &st) ||
 805                             ce_match_stat(old, &st, 1))
 806                                 old->ce_flags |= htons(CE_UPDATE);
 807                 }
 808                 return keep_entry(old);
 809         }
 810         return merged_entry(a, old, o);
 811 }