unpack-trees.c

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