unpack-trees.c

   1 #define NO_THE_INDEX_COMPATIBILITY_MACROS
   2 #include "cache.h"
   3 #include "dir.h"
   4 #include "tree.h"
   5 #include "tree-walk.h"
   6 #include "cache-tree.h"
   7 #include "unpack-trees.h"
   8 #include "progress.h"
   9 #include "refs.h"
  10 #include "attr.h"
  11
  12 /*
  13  * Error messages expected by scripts out of plumbing commands such as
  14  * read-tree.  Non-scripted Porcelain is not required to use these messages
  15  * and in fact are encouraged to reword them to better suit their particular
  16  * situation better.  See how "git checkout" replaces not_uptodate_file to
  17  * explain why it does not allow switching between branches when you have
  18  * local changes, for example.
  19  */
  20 static struct unpack_trees_error_msgs unpack_plumbing_errors = {
  21         /* would_overwrite */
  22         "Entry '%s' would be overwritten by merge. Cannot merge.",
  23
  24         /* not_uptodate_file */
  25         "Entry '%s' not uptodate. Cannot merge.",
  26
  27         /* not_uptodate_dir */
  28         "Updating '%s' would lose untracked files in it",
  29
  30         /* would_lose_untracked */
  31         "Untracked working tree file '%s' would be %s by merge.",
  32
  33         /* bind_overlap */
  34         "Entry '%s' overlaps with '%s'.  Cannot bind.",
  35 };
  36
  37 #define ERRORMSG(o,fld) \
  38         ( ((o) && (o)->msgs.fld) \
  39         ? ((o)->msgs.fld) \
  40         : (unpack_plumbing_errors.fld) )
  41
  42 static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
  43         unsigned int set, unsigned int clear)
  44 {
  45         unsigned int size = ce_size(ce);
  46         struct cache_entry *new = xmalloc(size);
  47
  48         clear |= CE_HASHED | CE_UNHASHED;
  49
  50         memcpy(new, ce, size);
  51         new->next = NULL;
  52         new->ce_flags = (new->ce_flags & ~clear) | set;
  53         add_index_entry(&o->result, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
  54 }
  55
  56 /*
  57  * Unlink the last component and schedule the leading directories for
  58  * removal, such that empty directories get removed.
  59  */
  60 static void unlink_entry(struct cache_entry *ce)
  61 {
  62         if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
  63                 return;
  64         if (unlink_or_warn(ce->name))
  65                 return;
  66         schedule_dir_for_removal(ce->name, ce_namelen(ce));
  67 }
  68
  69 static struct checkout state;
  70 static int check_updates(struct unpack_trees_options *o)
  71 {
  72         unsigned cnt = 0, total = 0;
  73         struct progress *progress = NULL;
  74         struct index_state *index = &o->result;
  75         int i;
  76         int errs = 0;
  77
  78         if (o->update && o->verbose_update) {
  79                 for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
  80                         struct cache_entry *ce = index->cache[cnt];
  81                         if (ce->ce_flags & (CE_UPDATE | CE_REMOVE | CE_WT_REMOVE))
  82                                 total++;
  83                 }
  84
  85                 progress = start_progress_delay("Checking out files",
  86                                                 total, 50, 1);
  87                 cnt = 0;
  88         }
  89
  90         if (o->update)
  91                 git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
  92         for (i = 0; i < index->cache_nr; i++) {
  93                 struct cache_entry *ce = index->cache[i];
  94
  95                 if (ce->ce_flags & CE_WT_REMOVE) {
  96                         display_progress(progress, ++cnt);
  97                         if (o->update)
  98                                 unlink_entry(ce);
  99                         continue;
 100                 }
 101
 102                 if (ce->ce_flags & CE_REMOVE) {
 103                         display_progress(progress, ++cnt);
 104                         if (o->update)
 105                                 unlink_entry(ce);
 106                 }
 107         }
 108         remove_marked_cache_entries(&o->result);
 109         remove_scheduled_dirs();
 110
 111         for (i = 0; i < index->cache_nr; i++) {
 112                 struct cache_entry *ce = index->cache[i];
 113
 114                 if (ce->ce_flags & CE_UPDATE) {
 115                         display_progress(progress, ++cnt);
 116                         ce->ce_flags &= ~CE_UPDATE;
 117                         if (o->update) {
 118                                 errs |= checkout_entry(ce, &state, NULL);
 119                         }
 120                 }
 121         }
 122         stop_progress(&progress);
 123         if (o->update)
 124                 git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
 125         return errs != 0;
 126 }
 127
 128 static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
 129 {
 130         int ret = o->fn(src, o);
 131         if (ret > 0)
 132                 ret = 0;
 133         return ret;
 134 }
 135
 136 static int unpack_index_entry(struct cache_entry *ce, struct unpack_trees_options *o)
 137 {
 138         struct cache_entry *src[5] = { ce, NULL, };
 139
 140         o->pos++;
 141         if (ce_stage(ce)) {
 142                 if (o->skip_unmerged) {
 143                         add_entry(o, ce, 0, 0);
 144                         return 0;
 145                 }
 146         }
 147         return call_unpack_fn(src, o);
 148 }
 149
 150 static int traverse_trees_recursive(int n, unsigned long dirmask, unsigned long df_conflicts, struct name_entry *names, struct traverse_info *info)
 151 {
 152         int i;
 153         struct tree_desc t[MAX_UNPACK_TREES];
 154         struct traverse_info newinfo;
 155         struct name_entry *p;
 156
 157         p = names;
 158         while (!p->mode)
 159                 p++;
 160
 161         newinfo = *info;
 162         newinfo.prev = info;
 163         newinfo.name = *p;
 164         newinfo.pathlen += tree_entry_len(p->path, p->sha1) + 1;
 165         newinfo.conflicts |= df_conflicts;
 166
 167         for (i = 0; i < n; i++, dirmask >>= 1) {
 168                 const unsigned char *sha1 = NULL;
 169                 if (dirmask & 1)
 170                         sha1 = names[i].sha1;
 171                 fill_tree_descriptor(t+i, sha1);
 172         }
 173         return traverse_trees(n, t, &newinfo);
 174 }
 175
 176 /*
 177  * Compare the traverse-path to the cache entry without actually
 178  * having to generate the textual representation of the traverse
 179  * path.
 180  *
 181  * NOTE! This *only* compares up to the size of the traverse path
 182  * itself - the caller needs to do the final check for the cache
 183  * entry having more data at the end!
 184  */
 185 static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 186 {
 187         int len, pathlen, ce_len;
 188         const char *ce_name;
 189
 190         if (info->prev) {
 191                 int cmp = do_compare_entry(ce, info->prev, &info->name);
 192                 if (cmp)
 193                         return cmp;
 194         }
 195         pathlen = info->pathlen;
 196         ce_len = ce_namelen(ce);
 197
 198         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 199         if (ce_len < pathlen)
 200                 return -1;
 201
 202         ce_len -= pathlen;
 203         ce_name = ce->name + pathlen;
 204
 205         len = tree_entry_len(n->path, n->sha1);
 206         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 207 }
 208
 209 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 210 {
 211         int cmp = do_compare_entry(ce, info, n);
 212         if (cmp)
 213                 return cmp;
 214
 215         /*
 216          * Even if the beginning compared identically, the ce should
 217          * compare as bigger than a directory leading up to it!
 218          */
 219         return ce_namelen(ce) > traverse_path_len(info, n);
 220 }
 221
 222 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
 223 {
 224         int len = traverse_path_len(info, n);
 225         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
 226
 227         ce->ce_mode = create_ce_mode(n->mode);
 228         ce->ce_flags = create_ce_flags(len, stage);
 229         hashcpy(ce->sha1, n->sha1);
 230         make_traverse_path(ce->name, info, n);
 231
 232         return ce;
 233 }
 234
 235 static int unpack_nondirectories(int n, unsigned long mask,
 236                                  unsigned long dirmask,
 237                                  struct cache_entry **src,
 238                                  const struct name_entry *names,
 239                                  const struct traverse_info *info)
 240 {
 241         int i;
 242         struct unpack_trees_options *o = info->data;
 243         unsigned long conflicts;
 244
 245         /* Do we have *only* directories? Nothing to do */
 246         if (mask == dirmask && !src[0])
 247                 return 0;
 248
 249         conflicts = info->conflicts;
 250         if (o->merge)
 251                 conflicts >>= 1;
 252         conflicts |= dirmask;
 253
 254         /*
 255          * Ok, we've filled in up to any potential index entry in src[0],
 256          * now do the rest.
 257          */
 258         for (i = 0; i < n; i++) {
 259                 int stage;
 260                 unsigned int bit = 1ul << i;
 261                 if (conflicts & bit) {
 262                         src[i + o->merge] = o->df_conflict_entry;
 263                         continue;
 264                 }
 265                 if (!(mask & bit))
 266                         continue;
 267                 if (!o->merge)
 268                         stage = 0;
 269                 else if (i + 1 < o->head_idx)
 270                         stage = 1;
 271                 else if (i + 1 > o->head_idx)
 272                         stage = 3;
 273                 else
 274                         stage = 2;
 275                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
 276         }
 277
 278         if (o->merge)
 279                 return call_unpack_fn(src, o);
 280
 281         for (i = 0; i < n; i++)
 282                 if (src[i] && src[i] != o->df_conflict_entry)
 283                         add_entry(o, src[i], 0, 0);
 284         return 0;
 285 }
 286
 287 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
 288 {
 289         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 290         struct unpack_trees_options *o = info->data;
 291         const struct name_entry *p = names;
 292
 293         /* Find first entry with a real name (we could use "mask" too) */
 294         while (!p->mode)
 295                 p++;
 296
 297         /* Are we supposed to look at the index too? */
 298         if (o->merge) {
 299                 while (o->pos < o->src_index->cache_nr) {
 300                         struct cache_entry *ce = o->src_index->cache[o->pos];
 301                         int cmp = compare_entry(ce, info, p);
 302                         if (cmp < 0) {
 303                                 if (unpack_index_entry(ce, o) < 0)
 304                                         return -1;
 305                                 continue;
 306                         }
 307                         if (!cmp) {
 308                                 o->pos++;
 309                                 if (ce_stage(ce)) {
 310                                         /*
 311                                          * If we skip unmerged index entries, we'll skip this
 312                                          * entry *and* the tree entries associated with it!
 313                                          */
 314                                         if (o->skip_unmerged) {
 315                                                 add_entry(o, ce, 0, 0);
 316                                                 return mask;
 317                                         }
 318                                 }
 319                                 src[0] = ce;
 320                         }
 321                         break;
 322                 }
 323         }
 324
 325         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
 326                 return -1;
 327
 328         /* Now handle any directories.. */
 329         if (dirmask) {
 330                 unsigned long conflicts = mask & ~dirmask;
 331                 if (o->merge) {
 332                         conflicts <<= 1;
 333                         if (src[0])
 334                                 conflicts |= 1;
 335                 }
 336
 337                 /* special case: "diff-index --cached" looking at a tree */
 338                 if (o->diff_index_cached &&
 339                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
 340                         int matches;
 341                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
 342                                                                names, info);
 343                         /*
 344                          * Everything under the name matches.  Adjust o->pos to
 345                          * skip the entire hierarchy.
 346                          */
 347                         if (matches) {
 348                                 o->pos += matches;
 349                                 return mask;
 350                         }
 351                 }
 352
 353                 if (traverse_trees_recursive(n, dirmask, conflicts,
 354                                              names, info) < 0)
 355                         return -1;
 356                 return mask;
 357         }
 358
 359         return mask;
 360 }
 361
 362 static int unpack_failed(struct unpack_trees_options *o, const char *message)
 363 {
 364         discard_index(&o->result);
 365         if (!o->gently) {
 366                 if (message)
 367                         return error("%s", message);
 368                 return -1;
 369         }
 370         return -1;
 371 }
 372
 373 /*
 374  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
 375  * resulting index, -2 on failure to reflect the changes to the work tree.
 376  */
 377 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
 378 {
 379         int ret;
 380         static struct cache_entry *dfc;
 381
 382         if (len > MAX_UNPACK_TREES)
 383                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
 384         memset(&state, 0, sizeof(state));
 385         state.base_dir = "";
 386         state.force = 1;
 387         state.quiet = 1;
 388         state.refresh_cache = 1;
 389
 390         memset(&o->result, 0, sizeof(o->result));
 391         o->result.initialized = 1;
 392         if (o->src_index) {
 393                 o->result.timestamp.sec = o->src_index->timestamp.sec;
 394                 o->result.timestamp.nsec = o->src_index->timestamp.nsec;
 395         }
 396         o->merge_size = len;
 397
 398         if (!dfc)
 399                 dfc = xcalloc(1, cache_entry_size(0));
 400         o->df_conflict_entry = dfc;
 401
 402         if (len) {
 403                 const char *prefix = o->prefix ? o->prefix : "";
 404                 struct traverse_info info;
 405
 406                 setup_traverse_info(&info, prefix);
 407                 info.fn = unpack_callback;
 408                 info.data = o;
 409
 410                 if (traverse_trees(len, t, &info) < 0)
 411                         return unpack_failed(o, NULL);
 412         }
 413
 414         /* Any left-over entries in the index? */
 415         if (o->merge) {
 416                 while (o->pos < o->src_index->cache_nr) {
 417                         struct cache_entry *ce = o->src_index->cache[o->pos];
 418                         if (unpack_index_entry(ce, o) < 0)
 419                                 return unpack_failed(o, NULL);
 420                 }
 421         }
 422
 423         if (o->trivial_merges_only && o->nontrivial_merge)
 424                 return unpack_failed(o, "Merge requires file-level merging");
 425
 426         o->src_index = NULL;
 427         ret = check_updates(o) ? (-2) : 0;
 428         if (o->dst_index)
 429                 *o->dst_index = o->result;
 430         return ret;
 431 }
 432
 433 /* Here come the merge functions */
 434
 435 static int reject_merge(struct cache_entry *ce, struct unpack_trees_options *o)
 436 {
 437         return error(ERRORMSG(o, would_overwrite), ce->name);
 438 }
 439
 440 static int same(struct cache_entry *a, struct cache_entry *b)
 441 {
 442         if (!!a != !!b)
 443                 return 0;
 444         if (!a && !b)
 445                 return 1;
 446         return a->ce_mode == b->ce_mode &&
 447                !hashcmp(a->sha1, b->sha1);
 448 }
 449
 450
 451 /*
 452  * When a CE gets turned into an unmerged entry, we
 453  * want it to be up-to-date
 454  */
 455 static int verify_uptodate_1(struct cache_entry *ce,
 456                                    struct unpack_trees_options *o,
 457                                    const char *error_msg)
 458 {
 459         struct stat st;
 460
 461         if (o->index_only || (!ce_skip_worktree(ce) && (o->reset || ce_uptodate(ce))))
 462                 return 0;
 463
 464         if (!lstat(ce->name, &st)) {
 465                 unsigned changed = ie_match_stat(o->src_index, ce, &st, CE_MATCH_IGNORE_VALID);
 466                 if (!changed)
 467                         return 0;
 468                 /*
 469                  * NEEDSWORK: the current default policy is to allow
 470                  * submodule to be out of sync wrt the supermodule
 471                  * index.  This needs to be tightened later for
 472                  * submodules that are marked to be automatically
 473                  * checked out.
 474                  */
 475                 if (S_ISGITLINK(ce->ce_mode))
 476                         return 0;
 477                 errno = 0;
 478         }
 479         if (errno == ENOENT)
 480                 return 0;
 481         return o->gently ? -1 :
 482                 error(error_msg, ce->name);
 483 }
 484
 485 static int verify_uptodate(struct cache_entry *ce,
 486                            struct unpack_trees_options *o)
 487 {
 488         return verify_uptodate_1(ce, o, ERRORMSG(o, not_uptodate_file));
 489 }
 490
 491 static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
 492 {
 493         if (ce)
 494                 cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
 495 }
 496
 497 /*
 498  * Check that checking out ce->sha1 in subdir ce->name is not
 499  * going to overwrite any working files.
 500  *
 501  * Currently, git does not checkout subprojects during a superproject
 502  * checkout, so it is not going to overwrite anything.
 503  */
 504 static int verify_clean_submodule(struct cache_entry *ce, const char *action,
 505                                       struct unpack_trees_options *o)
 506 {
 507         return 0;
 508 }
 509
 510 static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
 511                                       struct unpack_trees_options *o)
 512 {
 513         /*
 514          * we are about to extract "ce->name"; we would not want to lose
 515          * anything in the existing directory there.
 516          */
 517         int namelen;
 518         int i;
 519         struct dir_struct d;
 520         char *pathbuf;
 521         int cnt = 0;
 522         unsigned char sha1[20];
 523
 524         if (S_ISGITLINK(ce->ce_mode) &&
 525             resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
 526                 /* If we are not going to update the submodule, then
 527                  * we don't care.
 528                  */
 529                 if (!hashcmp(sha1, ce->sha1))
 530                         return 0;
 531                 return verify_clean_submodule(ce, action, o);
 532         }
 533
 534         /*
 535          * First let's make sure we do not have a local modification
 536          * in that directory.
 537          */
 538         namelen = strlen(ce->name);
 539         for (i = o->pos; i < o->src_index->cache_nr; i++) {
 540                 struct cache_entry *ce2 = o->src_index->cache[i];
 541                 int len = ce_namelen(ce2);
 542                 if (len < namelen ||
 543                     strncmp(ce->name, ce2->name, namelen) ||
 544                     ce2->name[namelen] != '/')
 545                         break;
 546                 /*
 547                  * ce2->name is an entry in the subdirectory.
 548                  */
 549                 if (!ce_stage(ce2)) {
 550                         if (verify_uptodate(ce2, o))
 551                                 return -1;
 552                         add_entry(o, ce2, CE_REMOVE, 0);
 553                 }
 554                 cnt++;
 555         }
 556
 557         /*
 558          * Then we need to make sure that we do not lose a locally
 559          * present file that is not ignored.
 560          */
 561         pathbuf = xmalloc(namelen + 2);
 562         memcpy(pathbuf, ce->name, namelen);
 563         strcpy(pathbuf+namelen, "/");
 564
 565         memset(&d, 0, sizeof(d));
 566         if (o->dir)
 567                 d.exclude_per_dir = o->dir->exclude_per_dir;
 568         i = read_directory(&d, pathbuf, namelen+1, NULL);
 569         if (i)
 570                 return o->gently ? -1 :
 571                         error(ERRORMSG(o, not_uptodate_dir), ce->name);
 572         free(pathbuf);
 573         return cnt;
 574 }
 575
 576 /*
 577  * This gets called when there was no index entry for the tree entry 'dst',
 578  * but we found a file in the working tree that 'lstat()' said was fine,
 579  * and we're on a case-insensitive filesystem.
 580  *
 581  * See if we can find a case-insensitive match in the index that also
 582  * matches the stat information, and assume it's that other file!
 583  */
 584 static int icase_exists(struct unpack_trees_options *o, struct cache_entry *dst, struct stat *st)
 585 {
 586         struct cache_entry *src;
 587
 588         src = index_name_exists(o->src_index, dst->name, ce_namelen(dst), 1);
 589         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID);
 590 }
 591
 592 /*
 593  * We do not want to remove or overwrite a working tree file that
 594  * is not tracked, unless it is ignored.
 595  */
 596 static int verify_absent_1(struct cache_entry *ce, const char *action,
 597                                  struct unpack_trees_options *o,
 598                                  const char *error_msg)
 599 {
 600         struct stat st;
 601
 602         if (o->index_only || o->reset || !o->update)
 603                 return 0;
 604
 605         if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
 606                 return 0;
 607
 608         if (!lstat(ce->name, &st)) {
 609                 int ret;
 610                 int dtype = ce_to_dtype(ce);
 611                 struct cache_entry *result;
 612
 613                 /*
 614                  * It may be that the 'lstat()' succeeded even though
 615                  * target 'ce' was absent, because there is an old
 616                  * entry that is different only in case..
 617                  *
 618                  * Ignore that lstat() if it matches.
 619                  */
 620                 if (ignore_case && icase_exists(o, ce, &st))
 621                         return 0;
 622
 623                 if (o->dir && excluded(o->dir, ce->name, &dtype))
 624                         /*
 625                          * ce->name is explicitly excluded, so it is Ok to
 626                          * overwrite it.
 627                          */
 628                         return 0;
 629                 if (S_ISDIR(st.st_mode)) {
 630                         /*
 631                          * We are checking out path "foo" and
 632                          * found "foo/." in the working tree.
 633                          * This is tricky -- if we have modified
 634                          * files that are in "foo/" we would lose
 635                          * it.
 636                          */
 637                         ret = verify_clean_subdirectory(ce, action, o);
 638                         if (ret < 0)
 639                                 return ret;
 640
 641                         /*
 642                          * If this removed entries from the index,
 643                          * what that means is:
 644                          *
 645                          * (1) the caller unpack_callback() saw path/foo
 646                          * in the index, and it has not removed it because
 647                          * it thinks it is handling 'path' as blob with
 648                          * D/F conflict;
 649                          * (2) we will return "ok, we placed a merged entry
 650                          * in the index" which would cause o->pos to be
 651                          * incremented by one;
 652                          * (3) however, original o->pos now has 'path/foo'
 653                          * marked with "to be removed".
 654                          *
 655                          * We need to increment it by the number of
 656                          * deleted entries here.
 657                          */
 658                         o->pos += ret;
 659                         return 0;
 660                 }
 661
 662                 /*
 663                  * The previous round may already have decided to
 664                  * delete this path, which is in a subdirectory that
 665                  * is being replaced with a blob.
 666                  */
 667                 result = index_name_exists(&o->result, ce->name, ce_namelen(ce), 0);
 668                 if (result) {
 669                         if (result->ce_flags & CE_REMOVE)
 670                                 return 0;
 671                 }
 672
 673                 return o->gently ? -1 :
 674                         error(ERRORMSG(o, would_lose_untracked), ce->name, action);
 675         }
 676         return 0;
 677 }
 678 static int verify_absent(struct cache_entry *ce, const char *action,
 679                          struct unpack_trees_options *o)
 680 {
 681         return verify_absent_1(ce, action, o, ERRORMSG(o, would_lose_untracked));
 682 }
 683
 684 static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 685                 struct unpack_trees_options *o)
 686 {
 687         int update = CE_UPDATE;
 688
 689         if (old) {
 690                 /*
 691                  * See if we can re-use the old CE directly?
 692                  * That way we get the uptodate stat info.
 693                  *
 694                  * This also removes the UPDATE flag on a match; otherwise
 695                  * we will end up overwriting local changes in the work tree.
 696                  */
 697                 if (same(old, merge)) {
 698                         copy_cache_entry(merge, old);
 699                         update = 0;
 700                 } else {
 701                         if (verify_uptodate(old, o))
 702                                 return -1;
 703                         if (ce_skip_worktree(old))
 704                                 update |= CE_SKIP_WORKTREE;
 705                         invalidate_ce_path(old, o);
 706                 }
 707         }
 708         else {
 709                 if (verify_absent(merge, "overwritten", o))
 710                         return -1;
 711                 invalidate_ce_path(merge, o);
 712         }
 713
 714         add_entry(o, merge, update, CE_STAGEMASK);
 715         return 1;
 716 }
 717
 718 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
 719                 struct unpack_trees_options *o)
 720 {
 721         /* Did it exist in the index? */
 722         if (!old) {
 723                 if (verify_absent(ce, "removed", o))
 724                         return -1;
 725                 return 0;
 726         }
 727         if (verify_uptodate(old, o))
 728                 return -1;
 729         add_entry(o, ce, CE_REMOVE, 0);
 730         invalidate_ce_path(ce, o);
 731         return 1;
 732 }
 733
 734 static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
 735 {
 736         add_entry(o, ce, 0, 0);
 737         return 1;
 738 }
 739
 740 #if DBRT_DEBUG
 741 static void show_stage_entry(FILE *o,
 742                              const char *label, const struct cache_entry *ce)
 743 {
 744         if (!ce)
 745                 fprintf(o, "%s (missing)\n", label);
 746         else
 747                 fprintf(o, "%s%06o %s %d\t%s\n",
 748                         label,
 749                         ce->ce_mode,
 750                         sha1_to_hex(ce->sha1),
 751                         ce_stage(ce),
 752                         ce->name);
 753 }
 754 #endif
 755
 756 int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
 757 {
 758         struct cache_entry *index;
 759         struct cache_entry *head;
 760         struct cache_entry *remote = stages[o->head_idx + 1];
 761         int count;
 762         int head_match = 0;
 763         int remote_match = 0;
 764
 765         int df_conflict_head = 0;
 766         int df_conflict_remote = 0;
 767
 768         int any_anc_missing = 0;
 769         int no_anc_exists = 1;
 770         int i;
 771
 772         for (i = 1; i < o->head_idx; i++) {
 773                 if (!stages[i] || stages[i] == o->df_conflict_entry)
 774                         any_anc_missing = 1;
 775                 else
 776                         no_anc_exists = 0;
 777         }
 778
 779         index = stages[0];
 780         head = stages[o->head_idx];
 781
 782         if (head == o->df_conflict_entry) {
 783                 df_conflict_head = 1;
 784                 head = NULL;
 785         }
 786
 787         if (remote == o->df_conflict_entry) {
 788                 df_conflict_remote = 1;
 789                 remote = NULL;
 790         }
 791
 792         /* First, if there's a #16 situation, note that to prevent #13
 793          * and #14.
 794          */
 795         if (!same(remote, head)) {
 796                 for (i = 1; i < o->head_idx; i++) {
 797                         if (same(stages[i], head)) {
 798                                 head_match = i;
 799                         }
 800                         if (same(stages[i], remote)) {
 801                                 remote_match = i;
 802                         }
 803                 }
 804         }
 805
 806         /* We start with cases where the index is allowed to match
 807          * something other than the head: #14(ALT) and #2ALT, where it
 808          * is permitted to match the result instead.
 809          */
 810         /* #14, #14ALT, #2ALT */
 811         if (remote && !df_conflict_head && head_match && !remote_match) {
 812                 if (index && !same(index, remote) && !same(index, head))
 813                         return o->gently ? -1 : reject_merge(index, o);
 814                 return merged_entry(remote, index, o);
 815         }
 816         /*
 817          * If we have an entry in the index cache, then we want to
 818          * make sure that it matches head.
 819          */
 820         if (index && !same(index, head))
 821                 return o->gently ? -1 : reject_merge(index, o);
 822
 823         if (head) {
 824                 /* #5ALT, #15 */
 825                 if (same(head, remote))
 826                         return merged_entry(head, index, o);
 827                 /* #13, #3ALT */
 828                 if (!df_conflict_remote && remote_match && !head_match)
 829                         return merged_entry(head, index, o);
 830         }
 831
 832         /* #1 */
 833         if (!head && !remote && any_anc_missing)
 834                 return 0;
 835
 836         /* Under the new "aggressive" rule, we resolve mostly trivial
 837          * cases that we historically had git-merge-one-file resolve.
 838          */
 839         if (o->aggressive) {
 840                 int head_deleted = !head && !df_conflict_head;
 841                 int remote_deleted = !remote && !df_conflict_remote;
 842                 struct cache_entry *ce = NULL;
 843
 844                 if (index)
 845                         ce = index;
 846                 else if (head)
 847                         ce = head;
 848                 else if (remote)
 849                         ce = remote;
 850                 else {
 851                         for (i = 1; i < o->head_idx; i++) {
 852                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
 853                                         ce = stages[i];
 854                                         break;
 855                                 }
 856                         }
 857                 }
 858
 859                 /*
 860                  * Deleted in both.
 861                  * Deleted in one and unchanged in the other.
 862                  */
 863                 if ((head_deleted && remote_deleted) ||
 864                     (head_deleted && remote && remote_match) ||
 865                     (remote_deleted && head && head_match)) {
 866                         if (index)
 867                                 return deleted_entry(index, index, o);
 868                         if (ce && !head_deleted) {
 869                                 if (verify_absent(ce, "removed", o))
 870                                         return -1;
 871                         }
 872                         return 0;
 873                 }
 874                 /*
 875                  * Added in both, identically.
 876                  */
 877                 if (no_anc_exists && head && remote && same(head, remote))
 878                         return merged_entry(head, index, o);
 879
 880         }
 881
 882         /* Below are "no merge" cases, which require that the index be
 883          * up-to-date to avoid the files getting overwritten with
 884          * conflict resolution files.
 885          */
 886         if (index) {
 887                 if (verify_uptodate(index, o))
 888                         return -1;
 889         }
 890
 891         o->nontrivial_merge = 1;
 892
 893         /* #2, #3, #4, #6, #7, #9, #10, #11. */
 894         count = 0;
 895         if (!head_match || !remote_match) {
 896                 for (i = 1; i < o->head_idx; i++) {
 897                         if (stages[i] && stages[i] != o->df_conflict_entry) {
 898                                 keep_entry(stages[i], o);
 899                                 count++;
 900                                 break;
 901                         }
 902                 }
 903         }
 904 #if DBRT_DEBUG
 905         else {
 906                 fprintf(stderr, "read-tree: warning #16 detected\n");
 907                 show_stage_entry(stderr, "head   ", stages[head_match]);
 908                 show_stage_entry(stderr, "remote ", stages[remote_match]);
 909         }
 910 #endif
 911         if (head) { count += keep_entry(head, o); }
 912         if (remote) { count += keep_entry(remote, o); }
 913         return count;
 914 }
 915
 916 /*
 917  * Two-way merge.
 918  *
 919  * The rule is to "carry forward" what is in the index without losing
 920  * information across a "fast forward", favoring a successful merge
 921  * over a merge failure when it makes sense.  For details of the
 922  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
 923  *
 924  */
 925 int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
 926 {
 927         struct cache_entry *current = src[0];
 928         struct cache_entry *oldtree = src[1];
 929         struct cache_entry *newtree = src[2];
 930
 931         if (o->merge_size != 2)
 932                 return error("Cannot do a twoway merge of %d trees",
 933                              o->merge_size);
 934
 935         if (oldtree == o->df_conflict_entry)
 936                 oldtree = NULL;
 937         if (newtree == o->df_conflict_entry)
 938                 newtree = NULL;
 939
 940         if (current) {
 941                 if ((!oldtree && !newtree) || /* 4 and 5 */
 942                     (!oldtree && newtree &&
 943                      same(current, newtree)) || /* 6 and 7 */
 944                     (oldtree && newtree &&
 945                      same(oldtree, newtree)) || /* 14 and 15 */
 946                     (oldtree && newtree &&
 947                      !same(oldtree, newtree) && /* 18 and 19 */
 948                      same(current, newtree))) {
 949                         return keep_entry(current, o);
 950                 }
 951                 else if (oldtree && !newtree && same(current, oldtree)) {
 952                         /* 10 or 11 */
 953                         return deleted_entry(oldtree, current, o);
 954                 }
 955                 else if (oldtree && newtree &&
 956                          same(current, oldtree) && !same(current, newtree)) {
 957                         /* 20 or 21 */
 958                         return merged_entry(newtree, current, o);
 959                 }
 960                 else {
 961                         /* all other failures */
 962                         if (oldtree)
 963                                 return o->gently ? -1 : reject_merge(oldtree, o);
 964                         if (current)
 965                                 return o->gently ? -1 : reject_merge(current, o);
 966                         if (newtree)
 967                                 return o->gently ? -1 : reject_merge(newtree, o);
 968                         return -1;
 969                 }
 970         }
 971         else if (newtree) {
 972                 if (oldtree && !o->initial_checkout) {
 973                         /*
 974                          * deletion of the path was staged;
 975                          */
 976                         if (same(oldtree, newtree))
 977                                 return 1;
 978                         return reject_merge(oldtree, o);
 979                 }
 980                 return merged_entry(newtree, current, o);
 981         }
 982         return deleted_entry(oldtree, current, o);
 983 }
 984
 985 /*
 986  * Bind merge.
 987  *
 988  * Keep the index entries at stage0, collapse stage1 but make sure
 989  * stage0 does not have anything there.
 990  */
 991 int bind_merge(struct cache_entry **src,
 992                 struct unpack_trees_options *o)
 993 {
 994         struct cache_entry *old = src[0];
 995         struct cache_entry *a = src[1];
 996
 997         if (o->merge_size != 1)
 998                 return error("Cannot do a bind merge of %d trees\n",
 999                              o->merge_size);
1000         if (a && old)
1001                 return o->gently ? -1 :
1002                         error(ERRORMSG(o, bind_overlap), a->name, old->name);
1003         if (!a)
1004                 return keep_entry(old, o);
1005         else
1006                 return merged_entry(a, NULL, o);
1007 }
1008
1009 /*
1010  * One-way merge.
1011  *
1012  * The rule is:
1013  * - take the stat information from stage0, take the data from stage1
1014  */
1015 int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1016 {
1017         struct cache_entry *old = src[0];
1018         struct cache_entry *a = src[1];
1019
1020         if (o->merge_size != 1)
1021                 return error("Cannot do a oneway merge of %d trees",
1022                              o->merge_size);
1023
1024         if (!a || a == o->df_conflict_entry)
1025                 return deleted_entry(old, old, o);
1026
1027         if (old && same(old, a)) {
1028                 int update = 0;
1029                 if (o->reset && !ce_uptodate(old) && !ce_skip_worktree(old)) {
1030                         struct stat st;
1031                         if (lstat(old->name, &st) ||
1032                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID))
1033                                 update |= CE_UPDATE;
1034                 }
1035                 add_entry(o, old, update, 0);
1036                 return 0;
1037         }
1038         return merged_entry(a, old, o);
1039 }