unpack-trees.c

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