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         desc.buf = tree->buffer;
  31         desc.size = tree->size;
  32
  33         while (tree_entry(&desc, &one)) {
  34                 struct tree_entry_list *entry;
  35
  36                 entry = xmalloc(sizeof(struct tree_entry_list));
  37                 entry->name = one.path;
  38                 entry->sha1 = one.sha1;
  39                 entry->mode = one.mode;
  40                 entry->directory = S_ISDIR(one.mode) != 0;
  41                 entry->executable = (one.mode & S_IXUSR) != 0;
  42                 entry->symlink = S_ISLNK(one.mode) != 0;
  43                 entry->next = NULL;
  44
  45                 *list_p = entry;
  46                 list_p = &entry->next;
  47         }
  48         return ret;
  49 }
  50
  51 static int entcmp(const char *name1, int dir1, const char *name2, int dir2)
  52 {
  53         int len1 = strlen(name1);
  54         int len2 = strlen(name2);
  55         int len = len1 < len2 ? len1 : len2;
  56         int ret = memcmp(name1, name2, len);
  57         unsigned char c1, c2;
  58         if (ret)
  59                 return ret;
  60         c1 = name1[len];
  61         c2 = name2[len];
  62         if (!c1 && dir1)
  63                 c1 = '/';
  64         if (!c2 && dir2)
  65                 c2 = '/';
  66         ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
  67         if (c1 && c2 && !ret)
  68                 ret = len1 - len2;
  69         return ret;
  70 }
  71
  72 static int unpack_trees_rec(struct tree_entry_list **posns, int len,
  73                             const char *base, struct unpack_trees_options *o,
  74                             int *indpos,
  75                             struct tree_entry_list *df_conflict_list)
  76 {
  77         int baselen = strlen(base);
  78         int src_size = len + 1;
  79         int i_stk = i_stk;
  80         int retval = 0;
  81
  82         if (o->dir)
  83                 i_stk = push_exclude_per_directory(o->dir, base, strlen(base));
  84
  85         do {
  86                 int i;
  87                 const char *first;
  88                 int firstdir = 0;
  89                 int pathlen;
  90                 unsigned ce_size;
  91                 struct tree_entry_list **subposns;
  92                 struct cache_entry **src;
  93                 int any_files = 0;
  94                 int any_dirs = 0;
  95                 char *cache_name;
  96                 int ce_stage;
  97
  98                 /* Find the first name in the input. */
  99
 100                 first = NULL;
 101                 cache_name = NULL;
 102
 103                 /* Check the cache */
 104                 if (o->merge && *indpos < active_nr) {
 105                         /* This is a bit tricky: */
 106                         /* If the index has a subdirectory (with
 107                          * contents) as the first name, it'll get a
 108                          * filename like "foo/bar". But that's after
 109                          * "foo", so the entry in trees will get
 110                          * handled first, at which point we'll go into
 111                          * "foo", and deal with "bar" from the index,
 112                          * because the base will be "foo/". The only
 113                          * way we can actually have "foo/bar" first of
 114                          * all the things is if the trees don't
 115                          * contain "foo" at all, in which case we'll
 116                          * handle "foo/bar" without going into the
 117                          * directory, but that's fine (and will return
 118                          * an error anyway, with the added unknown
 119                          * file case.
 120                          */
 121
 122                         cache_name = active_cache[*indpos]->name;
 123                         if (strlen(cache_name) > baselen &&
 124                             !memcmp(cache_name, base, baselen)) {
 125                                 cache_name += baselen;
 126                                 first = cache_name;
 127                         } else {
 128                                 cache_name = NULL;
 129                         }
 130                 }
 131
 132 #if DBRT_DEBUG > 1
 133                 if (first)
 134                         printf("index %s\n", first);
 135 #endif
 136                 for (i = 0; i < len; i++) {
 137                         if (!posns[i] || posns[i] == df_conflict_list)
 138                                 continue;
 139 #if DBRT_DEBUG > 1
 140                         printf("%d %s\n", i + 1, posns[i]->name);
 141 #endif
 142                         if (!first || entcmp(first, firstdir,
 143                                              posns[i]->name,
 144                                              posns[i]->directory) > 0) {
 145                                 first = posns[i]->name;
 146                                 firstdir = posns[i]->directory;
 147                         }
 148                 }
 149                 /* No name means we're done */
 150                 if (!first)
 151                         goto leave_directory;
 152
 153                 pathlen = strlen(first);
 154                 ce_size = cache_entry_size(baselen + pathlen);
 155
 156                 src = xcalloc(src_size, sizeof(struct cache_entry *));
 157
 158                 subposns = xcalloc(len, sizeof(struct tree_list_entry *));
 159
 160                 if (cache_name && !strcmp(cache_name, first)) {
 161                         any_files = 1;
 162                         src[0] = active_cache[*indpos];
 163                         remove_cache_entry_at(*indpos);
 164                 }
 165
 166                 for (i = 0; i < len; i++) {
 167                         struct cache_entry *ce;
 168
 169                         if (!posns[i] ||
 170                             (posns[i] != df_conflict_list &&
 171                              strcmp(first, posns[i]->name))) {
 172                                 continue;
 173                         }
 174
 175                         if (posns[i] == df_conflict_list) {
 176                                 src[i + o->merge] = o->df_conflict_entry;
 177                                 continue;
 178                         }
 179
 180                         if (posns[i]->directory) {
 181                                 struct tree *tree = lookup_tree(posns[i]->sha1);
 182                                 any_dirs = 1;
 183                                 parse_tree(tree);
 184                                 subposns[i] = create_tree_entry_list(tree);
 185                                 posns[i] = posns[i]->next;
 186                                 src[i + o->merge] = o->df_conflict_entry;
 187                                 continue;
 188                         }
 189
 190                         if (!o->merge)
 191                                 ce_stage = 0;
 192                         else if (i + 1 < o->head_idx)
 193                                 ce_stage = 1;
 194                         else if (i + 1 > o->head_idx)
 195                                 ce_stage = 3;
 196                         else
 197                                 ce_stage = 2;
 198
 199                         ce = xcalloc(1, ce_size);
 200                         ce->ce_mode = create_ce_mode(posns[i]->mode);
 201                         ce->ce_flags = create_ce_flags(baselen + pathlen,
 202                                                        ce_stage);
 203                         memcpy(ce->name, base, baselen);
 204                         memcpy(ce->name + baselen, first, pathlen + 1);
 205
 206                         any_files = 1;
 207
 208                         hashcpy(ce->sha1, posns[i]->sha1);
 209                         src[i + o->merge] = ce;
 210                         subposns[i] = df_conflict_list;
 211                         posns[i] = posns[i]->next;
 212                 }
 213                 if (any_files) {
 214                         if (o->merge) {
 215                                 int ret;
 216
 217 #if DBRT_DEBUG > 1
 218                                 printf("%s:\n", first);
 219                                 for (i = 0; i < src_size; i++) {
 220                                         printf(" %d ", i);
 221                                         if (src[i])
 222                                                 printf("%s\n", sha1_to_hex(src[i]->sha1));
 223                                         else
 224                                                 printf("\n");
 225                                 }
 226 #endif
 227                                 ret = o->fn(src, o);
 228
 229 #if DBRT_DEBUG > 1
 230                                 printf("Added %d entries\n", ret);
 231 #endif
 232                                 *indpos += ret;
 233                         } else {
 234                                 for (i = 0; i < src_size; i++) {
 235                                         if (src[i]) {
 236                                                 add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
 237                                         }
 238                                 }
 239                         }
 240                 }
 241                 if (any_dirs) {
 242                         char *newbase = xmalloc(baselen + 2 + pathlen);
 243                         memcpy(newbase, base, baselen);
 244                         memcpy(newbase + baselen, first, pathlen);
 245                         newbase[baselen + pathlen] = '/';
 246                         newbase[baselen + pathlen + 1] = '\0';
 247                         if (unpack_trees_rec(subposns, len, newbase, o,
 248                                              indpos, df_conflict_list)) {
 249                                 retval = -1;
 250                                 goto leave_directory;
 251                         }
 252                         free(newbase);
 253                 }
 254                 free(subposns);
 255                 free(src);
 256         } while (1);
 257
 258  leave_directory:
 259         if (o->dir)
 260                 pop_exclude_per_directory(o->dir, i_stk);
 261         return retval;
 262 }
 263
 264 /* Unlink the last component and attempt to remove leading
 265  * directories, in case this unlink is the removal of the
 266  * last entry in the directory -- empty directories are removed.
 267  */
 268 static void unlink_entry(char *name)
 269 {
 270         char *cp, *prev;
 271
 272         if (unlink(name))
 273                 return;
 274         prev = NULL;
 275         while (1) {
 276                 int status;
 277                 cp = strrchr(name, '/');
 278                 if (prev)
 279                         *prev = '/';
 280                 if (!cp)
 281                         break;
 282
 283                 *cp = 0;
 284                 status = rmdir(name);
 285                 if (status) {
 286                         *cp = '/';
 287                         break;
 288                 }
 289                 prev = cp;
 290         }
 291 }
 292
 293 static volatile sig_atomic_t progress_update;
 294
 295 static void progress_interval(int signum)
 296 {
 297         progress_update = 1;
 298 }
 299
 300 static void setup_progress_signal(void)
 301 {
 302         struct sigaction sa;
 303         struct itimerval v;
 304
 305         memset(&sa, 0, sizeof(sa));
 306         sa.sa_handler = progress_interval;
 307         sigemptyset(&sa.sa_mask);
 308         sa.sa_flags = SA_RESTART;
 309         sigaction(SIGALRM, &sa, NULL);
 310
 311         v.it_interval.tv_sec = 1;
 312         v.it_interval.tv_usec = 0;
 313         v.it_value = v.it_interval;
 314         setitimer(ITIMER_REAL, &v, NULL);
 315 }
 316
 317 static struct checkout state;
 318 static void check_updates(struct cache_entry **src, int nr,
 319                 struct unpack_trees_options *o)
 320 {
 321         unsigned short mask = htons(CE_UPDATE);
 322         unsigned last_percent = 200, cnt = 0, total = 0;
 323
 324         if (o->update && o->verbose_update) {
 325                 for (total = cnt = 0; cnt < nr; cnt++) {
 326                         struct cache_entry *ce = src[cnt];
 327                         if (!ce->ce_mode || ce->ce_flags & mask)
 328                                 total++;
 329                 }
 330
 331                 /* Don't bother doing this for very small updates */
 332                 if (total < 250)
 333                         total = 0;
 334
 335                 if (total) {
 336                         fprintf(stderr, "Checking files out...\n");
 337                         setup_progress_signal();
 338                         progress_update = 1;
 339                 }
 340                 cnt = 0;
 341         }
 342
 343         while (nr--) {
 344                 struct cache_entry *ce = *src++;
 345
 346                 if (total) {
 347                         if (!ce->ce_mode || ce->ce_flags & mask) {
 348                                 unsigned percent;
 349                                 cnt++;
 350                                 percent = (cnt * 100) / total;
 351                                 if (percent != last_percent ||
 352                                     progress_update) {
 353                                         fprintf(stderr, "%4u%% (%u/%u) done\r",
 354                                                 percent, cnt, total);
 355                                         last_percent = percent;
 356                                         progress_update = 0;
 357                                 }
 358                         }
 359                 }
 360                 if (!ce->ce_mode) {
 361                         if (o->update)
 362                                 unlink_entry(ce->name);
 363                         continue;
 364                 }
 365                 if (ce->ce_flags & mask) {
 366                         ce->ce_flags &= ~mask;
 367                         if (o->update)
 368                                 checkout_entry(ce, &state, NULL);
 369                 }
 370         }
 371         if (total) {
 372                 signal(SIGALRM, SIG_IGN);
 373                 fputc('\n', stderr);
 374         }
 375 }
 376
 377 int unpack_trees(struct object_list *trees, struct unpack_trees_options *o)
 378 {
 379         int indpos = 0;
 380         unsigned len = object_list_length(trees);
 381         struct tree_entry_list **posns;
 382         int i;
 383         struct object_list *posn = trees;
 384         struct tree_entry_list df_conflict_list;
 385         static struct cache_entry *dfc;
 386
 387         memset(&df_conflict_list, 0, sizeof(df_conflict_list));
 388         df_conflict_list.next = &df_conflict_list;
 389         memset(&state, 0, sizeof(state));
 390         state.base_dir = "";
 391         state.force = 1;
 392         state.quiet = 1;
 393         state.refresh_cache = 1;
 394
 395         o->merge_size = len;
 396
 397         if (!dfc)
 398                 dfc = xcalloc(1, sizeof(struct cache_entry) + 1);
 399         o->df_conflict_entry = dfc;
 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 }