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         /* sparse_not_uptodate_file */
  37         "Entry '%s' not uptodate. Cannot update sparse checkout.",
  38
  39         /* would_lose_orphaned */
  40         "Working tree file '%s' would be %s by sparse checkout update.",
  41 };
  42
  43 #define ERRORMSG(o,fld) \
  44         ( ((o) && (o)->msgs.fld) \
  45         ? ((o)->msgs.fld) \
  46         : (unpack_plumbing_errors.fld) )
  47
  48 static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
  49         unsigned int set, unsigned int clear)
  50 {
  51         unsigned int size = ce_size(ce);
  52         struct cache_entry *new = xmalloc(size);
  53
  54         clear |= CE_HASHED | CE_UNHASHED;
  55
  56         memcpy(new, ce, size);
  57         new->next = NULL;
  58         new->ce_flags = (new->ce_flags & ~clear) | set;
  59         add_index_entry(&o->result, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
  60 }
  61
  62 /*
  63  * Unlink the last component and schedule the leading directories for
  64  * removal, such that empty directories get removed.
  65  */
  66 static void unlink_entry(struct cache_entry *ce)
  67 {
  68         if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
  69                 return;
  70         if (unlink_or_warn(ce->name))
  71                 return;
  72         schedule_dir_for_removal(ce->name, ce_namelen(ce));
  73 }
  74
  75 static struct checkout state;
  76 static int check_updates(struct unpack_trees_options *o)
  77 {
  78         unsigned cnt = 0, total = 0;
  79         struct progress *progress = NULL;
  80         struct index_state *index = &o->result;
  81         int i;
  82         int errs = 0;
  83
  84         if (o->update && o->verbose_update) {
  85                 for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
  86                         struct cache_entry *ce = index->cache[cnt];
  87                         if (ce->ce_flags & (CE_UPDATE | CE_REMOVE | CE_WT_REMOVE))
  88                                 total++;
  89                 }
  90
  91                 progress = start_progress_delay("Checking out files",
  92                                                 total, 50, 1);
  93                 cnt = 0;
  94         }
  95
  96         if (o->update)
  97                 git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
  98         for (i = 0; i < index->cache_nr; i++) {
  99                 struct cache_entry *ce = index->cache[i];
 100
 101                 if (ce->ce_flags & CE_WT_REMOVE) {
 102                         display_progress(progress, ++cnt);
 103                         if (o->update)
 104                                 unlink_entry(ce);
 105                         continue;
 106                 }
 107
 108                 if (ce->ce_flags & CE_REMOVE) {
 109                         display_progress(progress, ++cnt);
 110                         if (o->update)
 111                                 unlink_entry(ce);
 112                 }
 113         }
 114         remove_marked_cache_entries(&o->result);
 115         remove_scheduled_dirs();
 116
 117         for (i = 0; i < index->cache_nr; i++) {
 118                 struct cache_entry *ce = index->cache[i];
 119
 120                 if (ce->ce_flags & CE_UPDATE) {
 121                         display_progress(progress, ++cnt);
 122                         ce->ce_flags &= ~CE_UPDATE;
 123                         if (o->update) {
 124                                 errs |= checkout_entry(ce, &state, NULL);
 125                         }
 126                 }
 127         }
 128         stop_progress(&progress);
 129         if (o->update)
 130                 git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
 131         return errs != 0;
 132 }
 133
 134 static int verify_uptodate_sparse(struct cache_entry *ce, struct unpack_trees_options *o);
 135 static int verify_absent_sparse(struct cache_entry *ce, const char *action, struct unpack_trees_options *o);
 136
 137 static int will_have_skip_worktree(const struct cache_entry *ce, struct unpack_trees_options *o)
 138 {
 139         const char *basename;
 140
 141         if (ce_stage(ce))
 142                 return 0;
 143
 144         basename = strrchr(ce->name, '/');
 145         basename = basename ? basename+1 : ce->name;
 146         return excluded_from_list(ce->name, ce_namelen(ce), basename, NULL, o->el) <= 0;
 147 }
 148
 149 static int apply_sparse_checkout(struct cache_entry *ce, struct unpack_trees_options *o)
 150 {
 151         int was_skip_worktree = ce_skip_worktree(ce);
 152
 153         if (will_have_skip_worktree(ce, o))
 154                 ce->ce_flags |= CE_SKIP_WORKTREE;
 155         else
 156                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
 157
 158         /*
 159          * We only care about files getting into the checkout area
 160          * If merge strategies want to remove some, go ahead, this
 161          * flag will be removed eventually in unpack_trees() if it's
 162          * outside checkout area.
 163          */
 164         if (ce->ce_flags & CE_REMOVE)
 165                 return 0;
 166
 167         if (!was_skip_worktree && ce_skip_worktree(ce)) {
 168                 /*
 169                  * If CE_UPDATE is set, verify_uptodate() must be called already
 170                  * also stat info may have lost after merged_entry() so calling
 171                  * verify_uptodate() again may fail
 172                  */
 173                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
 174                         return -1;
 175                 ce->ce_flags |= CE_WT_REMOVE;
 176         }
 177         if (was_skip_worktree && !ce_skip_worktree(ce)) {
 178                 if (verify_absent_sparse(ce, "overwritten", o))
 179                         return -1;
 180                 ce->ce_flags |= CE_UPDATE;
 181         }
 182         return 0;
 183 }
 184
 185 static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
 186 {
 187         int ret = o->fn(src, o);
 188         if (ret > 0)
 189                 ret = 0;
 190         return ret;
 191 }
 192
 193 static int unpack_index_entry(struct cache_entry *ce, struct unpack_trees_options *o)
 194 {
 195         struct cache_entry *src[5] = { ce, NULL, };
 196
 197         o->pos++;
 198         if (ce_stage(ce)) {
 199                 if (o->skip_unmerged) {
 200                         add_entry(o, ce, 0, 0);
 201                         return 0;
 202                 }
 203         }
 204         return call_unpack_fn(src, o);
 205 }
 206
 207 static int traverse_trees_recursive(int n, unsigned long dirmask, unsigned long df_conflicts, struct name_entry *names, struct traverse_info *info)
 208 {
 209         int i;
 210         struct tree_desc t[MAX_UNPACK_TREES];
 211         struct traverse_info newinfo;
 212         struct name_entry *p;
 213
 214         p = names;
 215         while (!p->mode)
 216                 p++;
 217
 218         newinfo = *info;
 219         newinfo.prev = info;
 220         newinfo.name = *p;
 221         newinfo.pathlen += tree_entry_len(p->path, p->sha1) + 1;
 222         newinfo.conflicts |= df_conflicts;
 223
 224         for (i = 0; i < n; i++, dirmask >>= 1) {
 225                 const unsigned char *sha1 = NULL;
 226                 if (dirmask & 1)
 227                         sha1 = names[i].sha1;
 228                 fill_tree_descriptor(t+i, sha1);
 229         }
 230         return traverse_trees(n, t, &newinfo);
 231 }
 232
 233 /*
 234  * Compare the traverse-path to the cache entry without actually
 235  * having to generate the textual representation of the traverse
 236  * path.
 237  *
 238  * NOTE! This *only* compares up to the size of the traverse path
 239  * itself - the caller needs to do the final check for the cache
 240  * entry having more data at the end!
 241  */
 242 static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 243 {
 244         int len, pathlen, ce_len;
 245         const char *ce_name;
 246
 247         if (info->prev) {
 248                 int cmp = do_compare_entry(ce, info->prev, &info->name);
 249                 if (cmp)
 250                         return cmp;
 251         }
 252         pathlen = info->pathlen;
 253         ce_len = ce_namelen(ce);
 254
 255         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 256         if (ce_len < pathlen)
 257                 return -1;
 258
 259         ce_len -= pathlen;
 260         ce_name = ce->name + pathlen;
 261
 262         len = tree_entry_len(n->path, n->sha1);
 263         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 264 }
 265
 266 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 267 {
 268         int cmp = do_compare_entry(ce, info, n);
 269         if (cmp)
 270                 return cmp;
 271
 272         /*
 273          * Even if the beginning compared identically, the ce should
 274          * compare as bigger than a directory leading up to it!
 275          */
 276         return ce_namelen(ce) > traverse_path_len(info, n);
 277 }
 278
 279 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
 280 {
 281         int len = traverse_path_len(info, n);
 282         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
 283
 284         ce->ce_mode = create_ce_mode(n->mode);
 285         ce->ce_flags = create_ce_flags(len, stage);
 286         hashcpy(ce->sha1, n->sha1);
 287         make_traverse_path(ce->name, info, n);
 288
 289         return ce;
 290 }
 291
 292 static int unpack_nondirectories(int n, unsigned long mask,
 293                                  unsigned long dirmask,
 294                                  struct cache_entry **src,
 295                                  const struct name_entry *names,
 296                                  const struct traverse_info *info)
 297 {
 298         int i;
 299         struct unpack_trees_options *o = info->data;
 300         unsigned long conflicts;
 301
 302         /* Do we have *only* directories? Nothing to do */
 303         if (mask == dirmask && !src[0])
 304                 return 0;
 305
 306         conflicts = info->conflicts;
 307         if (o->merge)
 308                 conflicts >>= 1;
 309         conflicts |= dirmask;
 310
 311         /*
 312          * Ok, we've filled in up to any potential index entry in src[0],
 313          * now do the rest.
 314          */
 315         for (i = 0; i < n; i++) {
 316                 int stage;
 317                 unsigned int bit = 1ul << i;
 318                 if (conflicts & bit) {
 319                         src[i + o->merge] = o->df_conflict_entry;
 320                         continue;
 321                 }
 322                 if (!(mask & bit))
 323                         continue;
 324                 if (!o->merge)
 325                         stage = 0;
 326                 else if (i + 1 < o->head_idx)
 327                         stage = 1;
 328                 else if (i + 1 > o->head_idx)
 329                         stage = 3;
 330                 else
 331                         stage = 2;
 332                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
 333         }
 334
 335         if (o->merge)
 336                 return call_unpack_fn(src, o);
 337
 338         for (i = 0; i < n; i++)
 339                 if (src[i] && src[i] != o->df_conflict_entry)
 340                         add_entry(o, src[i], 0, 0);
 341         return 0;
 342 }
 343
 344 static int unpack_failed(struct unpack_trees_options *o, const char *message)
 345 {
 346         discard_index(&o->result);
 347         if (!o->gently) {
 348                 if (message)
 349                         return error("%s", message);
 350                 return -1;
 351         }
 352         return -1;
 353 }
 354
 355 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
 356 {
 357         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 358         struct unpack_trees_options *o = info->data;
 359         const struct name_entry *p = names;
 360
 361         /* Find first entry with a real name (we could use "mask" too) */
 362         while (!p->mode)
 363                 p++;
 364
 365         /* Are we supposed to look at the index too? */
 366         if (o->merge) {
 367                 while (o->pos < o->src_index->cache_nr) {
 368                         struct cache_entry *ce = o->src_index->cache[o->pos];
 369                         int cmp = compare_entry(ce, info, p);
 370                         if (cmp < 0) {
 371                                 if (unpack_index_entry(ce, o) < 0)
 372                                         return unpack_failed(o, NULL);
 373                                 continue;
 374                         }
 375                         if (!cmp) {
 376                                 o->pos++;
 377                                 if (ce_stage(ce)) {
 378                                         /*
 379                                          * If we skip unmerged index entries, we'll skip this
 380                                          * entry *and* the tree entries associated with it!
 381                                          */
 382                                         if (o->skip_unmerged) {
 383                                                 add_entry(o, ce, 0, 0);
 384                                                 return mask;
 385                                         }
 386                                 }
 387                                 src[0] = ce;
 388                         }
 389                         break;
 390                 }
 391         }
 392
 393         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
 394                 return -1;
 395
 396         /* Now handle any directories.. */
 397         if (dirmask) {
 398                 unsigned long conflicts = mask & ~dirmask;
 399                 if (o->merge) {
 400                         conflicts <<= 1;
 401                         if (src[0])
 402                                 conflicts |= 1;
 403                 }
 404
 405                 /* special case: "diff-index --cached" looking at a tree */
 406                 if (o->diff_index_cached &&
 407                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
 408                         int matches;
 409                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
 410                                                                names, info);
 411                         /*
 412                          * Everything under the name matches.  Adjust o->pos to
 413                          * skip the entire hierarchy.
 414                          */
 415                         if (matches) {
 416                                 o->pos += matches;
 417                                 return mask;
 418                         }
 419                 }
 420
 421                 if (traverse_trees_recursive(n, dirmask, conflicts,
 422                                              names, info) < 0)
 423                         return -1;
 424                 return mask;
 425         }
 426
 427         return mask;
 428 }
 429
 430 /*
 431  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
 432  * resulting index, -2 on failure to reflect the changes to the work tree.
 433  */
 434 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
 435 {
 436         int i, ret;
 437         static struct cache_entry *dfc;
 438         struct exclude_list el;
 439
 440         if (len > MAX_UNPACK_TREES)
 441                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
 442         memset(&state, 0, sizeof(state));
 443         state.base_dir = "";
 444         state.force = 1;
 445         state.quiet = 1;
 446         state.refresh_cache = 1;
 447
 448         memset(&el, 0, sizeof(el));
 449         if (!core_apply_sparse_checkout || !o->update)
 450                 o->skip_sparse_checkout = 1;
 451         if (!o->skip_sparse_checkout) {
 452                 if (add_excludes_from_file_to_list(git_path("info/sparse-checkout"), "", 0, NULL, &el, 0) < 0)
 453                         o->skip_sparse_checkout = 1;
 454                 else
 455                         o->el = &el;
 456         }
 457
 458         memset(&o->result, 0, sizeof(o->result));
 459         o->result.initialized = 1;
 460         if (o->src_index) {
 461                 o->result.timestamp.sec = o->src_index->timestamp.sec;
 462                 o->result.timestamp.nsec = o->src_index->timestamp.nsec;
 463         }
 464         o->merge_size = len;
 465
 466         if (!dfc)
 467                 dfc = xcalloc(1, cache_entry_size(0));
 468         o->df_conflict_entry = dfc;
 469
 470         if (len) {
 471                 const char *prefix = o->prefix ? o->prefix : "";
 472                 struct traverse_info info;
 473
 474                 setup_traverse_info(&info, prefix);
 475                 info.fn = unpack_callback;
 476                 info.data = o;
 477
 478                 if (traverse_trees(len, t, &info) < 0) {
 479                         ret = unpack_failed(o, NULL);
 480                         goto done;
 481                 }
 482         }
 483
 484         /* Any left-over entries in the index? */
 485         if (o->merge) {
 486                 while (o->pos < o->src_index->cache_nr) {
 487                         struct cache_entry *ce = o->src_index->cache[o->pos];
 488                         if (unpack_index_entry(ce, o) < 0) {
 489                                 ret = unpack_failed(o, NULL);
 490                                 goto done;
 491                         }
 492                 }
 493         }
 494
 495         if (o->trivial_merges_only && o->nontrivial_merge) {
 496                 ret = unpack_failed(o, "Merge requires file-level merging");
 497                 goto done;
 498         }
 499
 500         if (!o->skip_sparse_checkout) {
 501                 int empty_worktree = 1;
 502                 for (i = 0;i < o->result.cache_nr;i++) {
 503                         struct cache_entry *ce = o->result.cache[i];
 504
 505                         if (apply_sparse_checkout(ce, o)) {
 506                                 ret = -1;
 507                                 goto done;
 508                         }
 509                         /*
 510                          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
 511                          * area as a result of ce_skip_worktree() shortcuts in
 512                          * verify_absent() and verify_uptodate(). Clear them.
 513                          */
 514                         if (ce_skip_worktree(ce))
 515                                 ce->ce_flags &= ~(CE_UPDATE | CE_REMOVE);
 516                         else
 517                                 empty_worktree = 0;
 518
 519                 }
 520                 if (o->result.cache_nr && empty_worktree) {
 521                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
 522                         goto done;
 523                 }
 524         }
 525
 526         o->src_index = NULL;
 527         ret = check_updates(o) ? (-2) : 0;
 528         if (o->dst_index)
 529                 *o->dst_index = o->result;
 530
 531 done:
 532         for (i = 0;i < el.nr;i++)
 533                 free(el.excludes[i]);
 534         if (el.excludes)
 535                 free(el.excludes);
 536
 537         return ret;
 538 }
 539
 540 /* Here come the merge functions */
 541
 542 static int reject_merge(struct cache_entry *ce, struct unpack_trees_options *o)
 543 {
 544         return error(ERRORMSG(o, would_overwrite), ce->name);
 545 }
 546
 547 static int same(struct cache_entry *a, struct cache_entry *b)
 548 {
 549         if (!!a != !!b)
 550                 return 0;
 551         if (!a && !b)
 552                 return 1;
 553         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
 554                 return 0;
 555         return a->ce_mode == b->ce_mode &&
 556                !hashcmp(a->sha1, b->sha1);
 557 }
 558
 559
 560 /*
 561  * When a CE gets turned into an unmerged entry, we
 562  * want it to be up-to-date
 563  */
 564 static int verify_uptodate_1(struct cache_entry *ce,
 565                                    struct unpack_trees_options *o,
 566                                    const char *error_msg)
 567 {
 568         struct stat st;
 569
 570         if (o->index_only || (!ce_skip_worktree(ce) && (o->reset || ce_uptodate(ce))))
 571                 return 0;
 572
 573         if (!lstat(ce->name, &st)) {
 574                 unsigned changed = ie_match_stat(o->src_index, ce, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
 575                 if (!changed)
 576                         return 0;
 577                 /*
 578                  * NEEDSWORK: the current default policy is to allow
 579                  * submodule to be out of sync wrt the supermodule
 580                  * index.  This needs to be tightened later for
 581                  * submodules that are marked to be automatically
 582                  * checked out.
 583                  */
 584                 if (S_ISGITLINK(ce->ce_mode))
 585                         return 0;
 586                 errno = 0;
 587         }
 588         if (errno == ENOENT)
 589                 return 0;
 590         return o->gently ? -1 :
 591                 error(error_msg, ce->name);
 592 }
 593
 594 static int verify_uptodate(struct cache_entry *ce,
 595                            struct unpack_trees_options *o)
 596 {
 597         if (!o->skip_sparse_checkout && will_have_skip_worktree(ce, o))
 598                 return 0;
 599         return verify_uptodate_1(ce, o, ERRORMSG(o, not_uptodate_file));
 600 }
 601
 602 static int verify_uptodate_sparse(struct cache_entry *ce,
 603                                   struct unpack_trees_options *o)
 604 {
 605         return verify_uptodate_1(ce, o, ERRORMSG(o, sparse_not_uptodate_file));
 606 }
 607
 608 static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
 609 {
 610         if (ce)
 611                 cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
 612 }
 613
 614 /*
 615  * Check that checking out ce->sha1 in subdir ce->name is not
 616  * going to overwrite any working files.
 617  *
 618  * Currently, git does not checkout subprojects during a superproject
 619  * checkout, so it is not going to overwrite anything.
 620  */
 621 static int verify_clean_submodule(struct cache_entry *ce, const char *action,
 622                                       struct unpack_trees_options *o)
 623 {
 624         return 0;
 625 }
 626
 627 static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
 628                                       struct unpack_trees_options *o)
 629 {
 630         /*
 631          * we are about to extract "ce->name"; we would not want to lose
 632          * anything in the existing directory there.
 633          */
 634         int namelen;
 635         int i;
 636         struct dir_struct d;
 637         char *pathbuf;
 638         int cnt = 0;
 639         unsigned char sha1[20];
 640
 641         if (S_ISGITLINK(ce->ce_mode) &&
 642             resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
 643                 /* If we are not going to update the submodule, then
 644                  * we don't care.
 645                  */
 646                 if (!hashcmp(sha1, ce->sha1))
 647                         return 0;
 648                 return verify_clean_submodule(ce, action, o);
 649         }
 650
 651         /*
 652          * First let's make sure we do not have a local modification
 653          * in that directory.
 654          */
 655         namelen = strlen(ce->name);
 656         for (i = o->pos; i < o->src_index->cache_nr; i++) {
 657                 struct cache_entry *ce2 = o->src_index->cache[i];
 658                 int len = ce_namelen(ce2);
 659                 if (len < namelen ||
 660                     strncmp(ce->name, ce2->name, namelen) ||
 661                     ce2->name[namelen] != '/')
 662                         break;
 663                 /*
 664                  * ce2->name is an entry in the subdirectory.
 665                  */
 666                 if (!ce_stage(ce2)) {
 667                         if (verify_uptodate(ce2, o))
 668                                 return -1;
 669                         add_entry(o, ce2, CE_REMOVE, 0);
 670                 }
 671                 cnt++;
 672         }
 673
 674         /*
 675          * Then we need to make sure that we do not lose a locally
 676          * present file that is not ignored.
 677          */
 678         pathbuf = xmalloc(namelen + 2);
 679         memcpy(pathbuf, ce->name, namelen);
 680         strcpy(pathbuf+namelen, "/");
 681
 682         memset(&d, 0, sizeof(d));
 683         if (o->dir)
 684                 d.exclude_per_dir = o->dir->exclude_per_dir;
 685         i = read_directory(&d, pathbuf, namelen+1, NULL);
 686         if (i)
 687                 return o->gently ? -1 :
 688                         error(ERRORMSG(o, not_uptodate_dir), ce->name);
 689         free(pathbuf);
 690         return cnt;
 691 }
 692
 693 /*
 694  * This gets called when there was no index entry for the tree entry 'dst',
 695  * but we found a file in the working tree that 'lstat()' said was fine,
 696  * and we're on a case-insensitive filesystem.
 697  *
 698  * See if we can find a case-insensitive match in the index that also
 699  * matches the stat information, and assume it's that other file!
 700  */
 701 static int icase_exists(struct unpack_trees_options *o, struct cache_entry *dst, struct stat *st)
 702 {
 703         struct cache_entry *src;
 704
 705         src = index_name_exists(o->src_index, dst->name, ce_namelen(dst), 1);
 706         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
 707 }
 708
 709 /*
 710  * We do not want to remove or overwrite a working tree file that
 711  * is not tracked, unless it is ignored.
 712  */
 713 static int verify_absent_1(struct cache_entry *ce, const char *action,
 714                                  struct unpack_trees_options *o,
 715                                  const char *error_msg)
 716 {
 717         struct stat st;
 718
 719         if (o->index_only || o->reset || !o->update)
 720                 return 0;
 721
 722         if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
 723                 return 0;
 724
 725         if (!lstat(ce->name, &st)) {
 726                 int ret;
 727                 int dtype = ce_to_dtype(ce);
 728                 struct cache_entry *result;
 729
 730                 /*
 731                  * It may be that the 'lstat()' succeeded even though
 732                  * target 'ce' was absent, because there is an old
 733                  * entry that is different only in case..
 734                  *
 735                  * Ignore that lstat() if it matches.
 736                  */
 737                 if (ignore_case && icase_exists(o, ce, &st))
 738                         return 0;
 739
 740                 if (o->dir && excluded(o->dir, ce->name, &dtype))
 741                         /*
 742                          * ce->name is explicitly excluded, so it is Ok to
 743                          * overwrite it.
 744                          */
 745                         return 0;
 746                 if (S_ISDIR(st.st_mode)) {
 747                         /*
 748                          * We are checking out path "foo" and
 749                          * found "foo/." in the working tree.
 750                          * This is tricky -- if we have modified
 751                          * files that are in "foo/" we would lose
 752                          * them.
 753                          */
 754                         ret = verify_clean_subdirectory(ce, action, o);
 755                         if (ret < 0)
 756                                 return ret;
 757
 758                         /*
 759                          * If this removed entries from the index,
 760                          * what that means is:
 761                          *
 762                          * (1) the caller unpack_callback() saw path/foo
 763                          * in the index, and it has not removed it because
 764                          * it thinks it is handling 'path' as blob with
 765                          * D/F conflict;
 766                          * (2) we will return "ok, we placed a merged entry
 767                          * in the index" which would cause o->pos to be
 768                          * incremented by one;
 769                          * (3) however, original o->pos now has 'path/foo'
 770                          * marked with "to be removed".
 771                          *
 772                          * We need to increment it by the number of
 773                          * deleted entries here.
 774                          */
 775                         o->pos += ret;
 776                         return 0;
 777                 }
 778
 779                 /*
 780                  * The previous round may already have decided to
 781                  * delete this path, which is in a subdirectory that
 782                  * is being replaced with a blob.
 783                  */
 784                 result = index_name_exists(&o->result, ce->name, ce_namelen(ce), 0);
 785                 if (result) {
 786                         if (result->ce_flags & CE_REMOVE)
 787                                 return 0;
 788                 }
 789
 790                 return o->gently ? -1 :
 791                         error(ERRORMSG(o, would_lose_untracked), ce->name, action);
 792         }
 793         return 0;
 794 }
 795 static int verify_absent(struct cache_entry *ce, const char *action,
 796                          struct unpack_trees_options *o)
 797 {
 798         if (!o->skip_sparse_checkout && will_have_skip_worktree(ce, o))
 799                 return 0;
 800         return verify_absent_1(ce, action, o, ERRORMSG(o, would_lose_untracked));
 801 }
 802
 803 static int verify_absent_sparse(struct cache_entry *ce, const char *action,
 804                          struct unpack_trees_options *o)
 805 {
 806         return verify_absent_1(ce, action, o, ERRORMSG(o, would_lose_orphaned));
 807 }
 808
 809 static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 810                 struct unpack_trees_options *o)
 811 {
 812         int update = CE_UPDATE;
 813
 814         if (!old) {
 815                 if (verify_absent(merge, "overwritten", o))
 816                         return -1;
 817                 invalidate_ce_path(merge, o);
 818         } else if (!(old->ce_flags & CE_CONFLICTED)) {
 819                 /*
 820                  * See if we can re-use the old CE directly?
 821                  * That way we get the uptodate stat info.
 822                  *
 823                  * This also removes the UPDATE flag on a match; otherwise
 824                  * we will end up overwriting local changes in the work tree.
 825                  */
 826                 if (same(old, merge)) {
 827                         copy_cache_entry(merge, old);
 828                         update = 0;
 829                 } else {
 830                         if (verify_uptodate(old, o))
 831                                 return -1;
 832                         if (ce_skip_worktree(old))
 833                                 update |= CE_SKIP_WORKTREE;
 834                         invalidate_ce_path(old, o);
 835                 }
 836         } else {
 837                 /*
 838                  * Previously unmerged entry left as an existence
 839                  * marker by read_index_unmerged();
 840                  */
 841                 invalidate_ce_path(old, o);
 842         }
 843
 844         add_entry(o, merge, update, CE_STAGEMASK);
 845         return 1;
 846 }
 847
 848 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
 849                 struct unpack_trees_options *o)
 850 {
 851         /* Did it exist in the index? */
 852         if (!old) {
 853                 if (verify_absent(ce, "removed", o))
 854                         return -1;
 855                 return 0;
 856         }
 857         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
 858                 return -1;
 859         add_entry(o, ce, CE_REMOVE, 0);
 860         invalidate_ce_path(ce, o);
 861         return 1;
 862 }
 863
 864 static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
 865 {
 866         add_entry(o, ce, 0, 0);
 867         return 1;
 868 }
 869
 870 #if DBRT_DEBUG
 871 static void show_stage_entry(FILE *o,
 872                              const char *label, const struct cache_entry *ce)
 873 {
 874         if (!ce)
 875                 fprintf(o, "%s (missing)\n", label);
 876         else
 877                 fprintf(o, "%s%06o %s %d\t%s\n",
 878                         label,
 879                         ce->ce_mode,
 880                         sha1_to_hex(ce->sha1),
 881                         ce_stage(ce),
 882                         ce->name);
 883 }
 884 #endif
 885
 886 int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
 887 {
 888         struct cache_entry *index;
 889         struct cache_entry *head;
 890         struct cache_entry *remote = stages[o->head_idx + 1];
 891         int count;
 892         int head_match = 0;
 893         int remote_match = 0;
 894
 895         int df_conflict_head = 0;
 896         int df_conflict_remote = 0;
 897
 898         int any_anc_missing = 0;
 899         int no_anc_exists = 1;
 900         int i;
 901
 902         for (i = 1; i < o->head_idx; i++) {
 903                 if (!stages[i] || stages[i] == o->df_conflict_entry)
 904                         any_anc_missing = 1;
 905                 else
 906                         no_anc_exists = 0;
 907         }
 908
 909         index = stages[0];
 910         head = stages[o->head_idx];
 911
 912         if (head == o->df_conflict_entry) {
 913                 df_conflict_head = 1;
 914                 head = NULL;
 915         }
 916
 917         if (remote == o->df_conflict_entry) {
 918                 df_conflict_remote = 1;
 919                 remote = NULL;
 920         }
 921
 922         /* First, if there's a #16 situation, note that to prevent #13
 923          * and #14.
 924          */
 925         if (!same(remote, head)) {
 926                 for (i = 1; i < o->head_idx; i++) {
 927                         if (same(stages[i], head)) {
 928                                 head_match = i;
 929                         }
 930                         if (same(stages[i], remote)) {
 931                                 remote_match = i;
 932                         }
 933                 }
 934         }
 935
 936         /* We start with cases where the index is allowed to match
 937          * something other than the head: #14(ALT) and #2ALT, where it
 938          * is permitted to match the result instead.
 939          */
 940         /* #14, #14ALT, #2ALT */
 941         if (remote && !df_conflict_head && head_match && !remote_match) {
 942                 if (index && !same(index, remote) && !same(index, head))
 943                         return o->gently ? -1 : reject_merge(index, o);
 944                 return merged_entry(remote, index, o);
 945         }
 946         /*
 947          * If we have an entry in the index cache, then we want to
 948          * make sure that it matches head.
 949          */
 950         if (index && !same(index, head))
 951                 return o->gently ? -1 : reject_merge(index, o);
 952
 953         if (head) {
 954                 /* #5ALT, #15 */
 955                 if (same(head, remote))
 956                         return merged_entry(head, index, o);
 957                 /* #13, #3ALT */
 958                 if (!df_conflict_remote && remote_match && !head_match)
 959                         return merged_entry(head, index, o);
 960         }
 961
 962         /* #1 */
 963         if (!head && !remote && any_anc_missing)
 964                 return 0;
 965
 966         /* Under the new "aggressive" rule, we resolve mostly trivial
 967          * cases that we historically had git-merge-one-file resolve.
 968          */
 969         if (o->aggressive) {
 970                 int head_deleted = !head && !df_conflict_head;
 971                 int remote_deleted = !remote && !df_conflict_remote;
 972                 struct cache_entry *ce = NULL;
 973
 974                 if (index)
 975                         ce = index;
 976                 else if (head)
 977                         ce = head;
 978                 else if (remote)
 979                         ce = remote;
 980                 else {
 981                         for (i = 1; i < o->head_idx; i++) {
 982                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
 983                                         ce = stages[i];
 984                                         break;
 985                                 }
 986                         }
 987                 }
 988
 989                 /*
 990                  * Deleted in both.
 991                  * Deleted in one and unchanged in the other.
 992                  */
 993                 if ((head_deleted && remote_deleted) ||
 994                     (head_deleted && remote && remote_match) ||
 995                     (remote_deleted && head && head_match)) {
 996                         if (index)
 997                                 return deleted_entry(index, index, o);
 998                         if (ce && !head_deleted) {
 999                                 if (verify_absent(ce, "removed", o))
1000                                         return -1;
1001                         }
1002                         return 0;
1003                 }
1004                 /*
1005                  * Added in both, identically.
1006                  */
1007                 if (no_anc_exists && head && remote && same(head, remote))
1008                         return merged_entry(head, index, o);
1009
1010         }
1011
1012         /* Below are "no merge" cases, which require that the index be
1013          * up-to-date to avoid the files getting overwritten with
1014          * conflict resolution files.
1015          */
1016         if (index) {
1017                 if (verify_uptodate(index, o))
1018                         return -1;
1019         }
1020
1021         o->nontrivial_merge = 1;
1022
1023         /* #2, #3, #4, #6, #7, #9, #10, #11. */
1024         count = 0;
1025         if (!head_match || !remote_match) {
1026                 for (i = 1; i < o->head_idx; i++) {
1027                         if (stages[i] && stages[i] != o->df_conflict_entry) {
1028                                 keep_entry(stages[i], o);
1029                                 count++;
1030                                 break;
1031                         }
1032                 }
1033         }
1034 #if DBRT_DEBUG
1035         else {
1036                 fprintf(stderr, "read-tree: warning #16 detected\n");
1037                 show_stage_entry(stderr, "head   ", stages[head_match]);
1038                 show_stage_entry(stderr, "remote ", stages[remote_match]);
1039         }
1040 #endif
1041         if (head) { count += keep_entry(head, o); }
1042         if (remote) { count += keep_entry(remote, o); }
1043         return count;
1044 }
1045
1046 /*
1047  * Two-way merge.
1048  *
1049  * The rule is to "carry forward" what is in the index without losing
1050  * information across a "fast-forward", favoring a successful merge
1051  * over a merge failure when it makes sense.  For details of the
1052  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
1053  *
1054  */
1055 int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1056 {
1057         struct cache_entry *current = src[0];
1058         struct cache_entry *oldtree = src[1];
1059         struct cache_entry *newtree = src[2];
1060
1061         if (o->merge_size != 2)
1062                 return error("Cannot do a twoway merge of %d trees",
1063                              o->merge_size);
1064
1065         if (oldtree == o->df_conflict_entry)
1066                 oldtree = NULL;
1067         if (newtree == o->df_conflict_entry)
1068                 newtree = NULL;
1069
1070         if (current) {
1071                 if ((!oldtree && !newtree) || /* 4 and 5 */
1072                     (!oldtree && newtree &&
1073                      same(current, newtree)) || /* 6 and 7 */
1074                     (oldtree && newtree &&
1075                      same(oldtree, newtree)) || /* 14 and 15 */
1076                     (oldtree && newtree &&
1077                      !same(oldtree, newtree) && /* 18 and 19 */
1078                      same(current, newtree))) {
1079                         return keep_entry(current, o);
1080                 }
1081                 else if (oldtree && !newtree && same(current, oldtree)) {
1082                         /* 10 or 11 */
1083                         return deleted_entry(oldtree, current, o);
1084                 }
1085                 else if (oldtree && newtree &&
1086                          same(current, oldtree) && !same(current, newtree)) {
1087                         /* 20 or 21 */
1088                         return merged_entry(newtree, current, o);
1089                 }
1090                 else {
1091                         /* all other failures */
1092                         if (oldtree)
1093                                 return o->gently ? -1 : reject_merge(oldtree, o);
1094                         if (current)
1095                                 return o->gently ? -1 : reject_merge(current, o);
1096                         if (newtree)
1097                                 return o->gently ? -1 : reject_merge(newtree, o);
1098                         return -1;
1099                 }
1100         }
1101         else if (newtree) {
1102                 if (oldtree && !o->initial_checkout) {
1103                         /*
1104                          * deletion of the path was staged;
1105                          */
1106                         if (same(oldtree, newtree))
1107                                 return 1;
1108                         return reject_merge(oldtree, o);
1109                 }
1110                 return merged_entry(newtree, current, o);
1111         }
1112         return deleted_entry(oldtree, current, o);
1113 }
1114
1115 /*
1116  * Bind merge.
1117  *
1118  * Keep the index entries at stage0, collapse stage1 but make sure
1119  * stage0 does not have anything there.
1120  */
1121 int bind_merge(struct cache_entry **src,
1122                 struct unpack_trees_options *o)
1123 {
1124         struct cache_entry *old = src[0];
1125         struct cache_entry *a = src[1];
1126
1127         if (o->merge_size != 1)
1128                 return error("Cannot do a bind merge of %d trees\n",
1129                              o->merge_size);
1130         if (a && old)
1131                 return o->gently ? -1 :
1132                         error(ERRORMSG(o, bind_overlap), a->name, old->name);
1133         if (!a)
1134                 return keep_entry(old, o);
1135         else
1136                 return merged_entry(a, NULL, o);
1137 }
1138
1139 /*
1140  * One-way merge.
1141  *
1142  * The rule is:
1143  * - take the stat information from stage0, take the data from stage1
1144  */
1145 int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1146 {
1147         struct cache_entry *old = src[0];
1148         struct cache_entry *a = src[1];
1149
1150         if (o->merge_size != 1)
1151                 return error("Cannot do a oneway merge of %d trees",
1152                              o->merge_size);
1153
1154         if (!a || a == o->df_conflict_entry)
1155                 return deleted_entry(old, old, o);
1156
1157         if (old && same(old, a)) {
1158                 int update = 0;
1159                 if (o->reset && !ce_uptodate(old) && !ce_skip_worktree(old)) {
1160                         struct stat st;
1161                         if (lstat(old->name, &st) ||
1162                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
1163                                 update |= CE_UPDATE;
1164                 }
1165                 add_entry(o, old, update, 0);
1166                 return 0;
1167         }
1168         return merged_entry(a, old, o);
1169 }