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 (S_ISGITLINK(ce->ce_mode)) {
  71                 if (rmdir(ce->name)) {
  72                         warning("unable to rmdir %s: %s",
  73                                 ce->name, strerror(errno));
  74                         return;
  75                 }
  76         }
  77         else
  78                 if (unlink_or_warn(ce->name))
  79                         return;
  80         schedule_dir_for_removal(ce->name, ce_namelen(ce));
  81 }
  82
  83 static struct checkout state;
  84 static int check_updates(struct unpack_trees_options *o)
  85 {
  86         unsigned cnt = 0, total = 0;
  87         struct progress *progress = NULL;
  88         struct index_state *index = &o->result;
  89         int i;
  90         int errs = 0;
  91
  92         if (o->update && o->verbose_update) {
  93                 for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
  94                         struct cache_entry *ce = index->cache[cnt];
  95                         if (ce->ce_flags & (CE_UPDATE | CE_REMOVE | CE_WT_REMOVE))
  96                                 total++;
  97                 }
  98
  99                 progress = start_progress_delay("Checking out files",
 100                                                 total, 50, 1);
 101                 cnt = 0;
 102         }
 103
 104         if (o->update)
 105                 git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
 106         for (i = 0; i < index->cache_nr; i++) {
 107                 struct cache_entry *ce = index->cache[i];
 108
 109                 if (ce->ce_flags & CE_WT_REMOVE) {
 110                         display_progress(progress, ++cnt);
 111                         if (o->update)
 112                                 unlink_entry(ce);
 113                         continue;
 114                 }
 115
 116                 if (ce->ce_flags & CE_REMOVE) {
 117                         display_progress(progress, ++cnt);
 118                         if (o->update)
 119                                 unlink_entry(ce);
 120                 }
 121         }
 122         remove_marked_cache_entries(&o->result);
 123         remove_scheduled_dirs();
 124
 125         for (i = 0; i < index->cache_nr; i++) {
 126                 struct cache_entry *ce = index->cache[i];
 127
 128                 if (ce->ce_flags & CE_UPDATE) {
 129                         display_progress(progress, ++cnt);
 130                         ce->ce_flags &= ~CE_UPDATE;
 131                         if (o->update) {
 132                                 errs |= checkout_entry(ce, &state, NULL);
 133                         }
 134                 }
 135         }
 136         stop_progress(&progress);
 137         if (o->update)
 138                 git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
 139         return errs != 0;
 140 }
 141
 142 static int verify_uptodate_sparse(struct cache_entry *ce, struct unpack_trees_options *o);
 143 static int verify_absent_sparse(struct cache_entry *ce, const char *action, struct unpack_trees_options *o);
 144
 145 static int will_have_skip_worktree(const struct cache_entry *ce, struct unpack_trees_options *o)
 146 {
 147         const char *basename;
 148
 149         if (ce_stage(ce))
 150                 return 0;
 151
 152         basename = strrchr(ce->name, '/');
 153         basename = basename ? basename+1 : ce->name;
 154         return excluded_from_list(ce->name, ce_namelen(ce), basename, NULL, o->el) <= 0;
 155 }
 156
 157 static int apply_sparse_checkout(struct cache_entry *ce, struct unpack_trees_options *o)
 158 {
 159         int was_skip_worktree = ce_skip_worktree(ce);
 160
 161         if (will_have_skip_worktree(ce, o))
 162                 ce->ce_flags |= CE_SKIP_WORKTREE;
 163         else
 164                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
 165
 166         /*
 167          * We only care about files getting into the checkout area
 168          * If merge strategies want to remove some, go ahead, this
 169          * flag will be removed eventually in unpack_trees() if it's
 170          * outside checkout area.
 171          */
 172         if (ce->ce_flags & CE_REMOVE)
 173                 return 0;
 174
 175         if (!was_skip_worktree && ce_skip_worktree(ce)) {
 176                 /*
 177                  * If CE_UPDATE is set, verify_uptodate() must be called already
 178                  * also stat info may have lost after merged_entry() so calling
 179                  * verify_uptodate() again may fail
 180                  */
 181                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
 182                         return -1;
 183                 ce->ce_flags |= CE_WT_REMOVE;
 184         }
 185         if (was_skip_worktree && !ce_skip_worktree(ce)) {
 186                 if (verify_absent_sparse(ce, "overwritten", o))
 187                         return -1;
 188                 ce->ce_flags |= CE_UPDATE;
 189         }
 190         return 0;
 191 }
 192
 193 static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
 194 {
 195         int ret = o->fn(src, o);
 196         if (ret > 0)
 197                 ret = 0;
 198         return ret;
 199 }
 200
 201 static int unpack_index_entry(struct cache_entry *ce, struct unpack_trees_options *o)
 202 {
 203         struct cache_entry *src[5] = { ce, NULL, };
 204
 205         o->pos++;
 206         if (ce_stage(ce)) {
 207                 if (o->skip_unmerged) {
 208                         add_entry(o, ce, 0, 0);
 209                         return 0;
 210                 }
 211         }
 212         return call_unpack_fn(src, o);
 213 }
 214
 215 static int traverse_trees_recursive(int n, unsigned long dirmask, unsigned long df_conflicts, struct name_entry *names, struct traverse_info *info)
 216 {
 217         int i;
 218         struct tree_desc t[MAX_UNPACK_TREES];
 219         struct traverse_info newinfo;
 220         struct name_entry *p;
 221
 222         p = names;
 223         while (!p->mode)
 224                 p++;
 225
 226         newinfo = *info;
 227         newinfo.prev = info;
 228         newinfo.name = *p;
 229         newinfo.pathlen += tree_entry_len(p->path, p->sha1) + 1;
 230         newinfo.conflicts |= df_conflicts;
 231
 232         for (i = 0; i < n; i++, dirmask >>= 1) {
 233                 const unsigned char *sha1 = NULL;
 234                 if (dirmask & 1)
 235                         sha1 = names[i].sha1;
 236                 fill_tree_descriptor(t+i, sha1);
 237         }
 238         return traverse_trees(n, t, &newinfo);
 239 }
 240
 241 /*
 242  * Compare the traverse-path to the cache entry without actually
 243  * having to generate the textual representation of the traverse
 244  * path.
 245  *
 246  * NOTE! This *only* compares up to the size of the traverse path
 247  * itself - the caller needs to do the final check for the cache
 248  * entry having more data at the end!
 249  */
 250 static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 251 {
 252         int len, pathlen, ce_len;
 253         const char *ce_name;
 254
 255         if (info->prev) {
 256                 int cmp = do_compare_entry(ce, info->prev, &info->name);
 257                 if (cmp)
 258                         return cmp;
 259         }
 260         pathlen = info->pathlen;
 261         ce_len = ce_namelen(ce);
 262
 263         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 264         if (ce_len < pathlen)
 265                 return -1;
 266
 267         ce_len -= pathlen;
 268         ce_name = ce->name + pathlen;
 269
 270         len = tree_entry_len(n->path, n->sha1);
 271         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 272 }
 273
 274 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 275 {
 276         int cmp = do_compare_entry(ce, info, n);
 277         if (cmp)
 278                 return cmp;
 279
 280         /*
 281          * Even if the beginning compared identically, the ce should
 282          * compare as bigger than a directory leading up to it!
 283          */
 284         return ce_namelen(ce) > traverse_path_len(info, n);
 285 }
 286
 287 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
 288 {
 289         int len = traverse_path_len(info, n);
 290         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
 291
 292         ce->ce_mode = create_ce_mode(n->mode);
 293         ce->ce_flags = create_ce_flags(len, stage);
 294         hashcpy(ce->sha1, n->sha1);
 295         make_traverse_path(ce->name, info, n);
 296
 297         return ce;
 298 }
 299
 300 static int unpack_nondirectories(int n, unsigned long mask,
 301                                  unsigned long dirmask,
 302                                  struct cache_entry **src,
 303                                  const struct name_entry *names,
 304                                  const struct traverse_info *info)
 305 {
 306         int i;
 307         struct unpack_trees_options *o = info->data;
 308         unsigned long conflicts;
 309
 310         /* Do we have *only* directories? Nothing to do */
 311         if (mask == dirmask && !src[0])
 312                 return 0;
 313
 314         conflicts = info->conflicts;
 315         if (o->merge)
 316                 conflicts >>= 1;
 317         conflicts |= dirmask;
 318
 319         /*
 320          * Ok, we've filled in up to any potential index entry in src[0],
 321          * now do the rest.
 322          */
 323         for (i = 0; i < n; i++) {
 324                 int stage;
 325                 unsigned int bit = 1ul << i;
 326                 if (conflicts & bit) {
 327                         src[i + o->merge] = o->df_conflict_entry;
 328                         continue;
 329                 }
 330                 if (!(mask & bit))
 331                         continue;
 332                 if (!o->merge)
 333                         stage = 0;
 334                 else if (i + 1 < o->head_idx)
 335                         stage = 1;
 336                 else if (i + 1 > o->head_idx)
 337                         stage = 3;
 338                 else
 339                         stage = 2;
 340                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
 341         }
 342
 343         if (o->merge)
 344                 return call_unpack_fn(src, o);
 345
 346         for (i = 0; i < n; i++)
 347                 if (src[i] && src[i] != o->df_conflict_entry)
 348                         add_entry(o, src[i], 0, 0);
 349         return 0;
 350 }
 351
 352 static int unpack_failed(struct unpack_trees_options *o, const char *message)
 353 {
 354         discard_index(&o->result);
 355         if (!o->gently) {
 356                 if (message)
 357                         return error("%s", message);
 358                 return -1;
 359         }
 360         return -1;
 361 }
 362
 363 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
 364 {
 365         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 366         struct unpack_trees_options *o = info->data;
 367         const struct name_entry *p = names;
 368
 369         /* Find first entry with a real name (we could use "mask" too) */
 370         while (!p->mode)
 371                 p++;
 372
 373         /* Are we supposed to look at the index too? */
 374         if (o->merge) {
 375                 while (o->pos < o->src_index->cache_nr) {
 376                         struct cache_entry *ce = o->src_index->cache[o->pos];
 377                         int cmp = compare_entry(ce, info, p);
 378                         if (cmp < 0) {
 379                                 if (unpack_index_entry(ce, o) < 0)
 380                                         return unpack_failed(o, NULL);
 381                                 continue;
 382                         }
 383                         if (!cmp) {
 384                                 o->pos++;
 385                                 if (ce_stage(ce)) {
 386                                         /*
 387                                          * If we skip unmerged index entries, we'll skip this
 388                                          * entry *and* the tree entries associated with it!
 389                                          */
 390                                         if (o->skip_unmerged) {
 391                                                 add_entry(o, ce, 0, 0);
 392                                                 return mask;
 393                                         }
 394                                 }
 395                                 src[0] = ce;
 396                         }
 397                         break;
 398                 }
 399         }
 400
 401         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
 402                 return -1;
 403
 404         /* Now handle any directories.. */
 405         if (dirmask) {
 406                 unsigned long conflicts = mask & ~dirmask;
 407                 if (o->merge) {
 408                         conflicts <<= 1;
 409                         if (src[0])
 410                                 conflicts |= 1;
 411                 }
 412
 413                 /* special case: "diff-index --cached" looking at a tree */
 414                 if (o->diff_index_cached &&
 415                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
 416                         int matches;
 417                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
 418                                                                names, info);
 419                         /*
 420                          * Everything under the name matches.  Adjust o->pos to
 421                          * skip the entire hierarchy.
 422                          */
 423                         if (matches) {
 424                                 o->pos += matches;
 425                                 return mask;
 426                         }
 427                 }
 428
 429                 if (traverse_trees_recursive(n, dirmask, conflicts,
 430                                              names, info) < 0)
 431                         return -1;
 432                 return mask;
 433         }
 434
 435         return mask;
 436 }
 437
 438 /*
 439  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
 440  * resulting index, -2 on failure to reflect the changes to the work tree.
 441  */
 442 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
 443 {
 444         int i, ret;
 445         static struct cache_entry *dfc;
 446         struct exclude_list el;
 447
 448         if (len > MAX_UNPACK_TREES)
 449                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
 450         memset(&state, 0, sizeof(state));
 451         state.base_dir = "";
 452         state.force = 1;
 453         state.quiet = 1;
 454         state.refresh_cache = 1;
 455
 456         memset(&el, 0, sizeof(el));
 457         if (!core_apply_sparse_checkout || !o->update)
 458                 o->skip_sparse_checkout = 1;
 459         if (!o->skip_sparse_checkout) {
 460                 if (add_excludes_from_file_to_list(git_path("info/sparse-checkout"), "", 0, NULL, &el, 0) < 0)
 461                         o->skip_sparse_checkout = 1;
 462                 else
 463                         o->el = &el;
 464         }
 465
 466         memset(&o->result, 0, sizeof(o->result));
 467         o->result.initialized = 1;
 468         if (o->src_index) {
 469                 o->result.timestamp.sec = o->src_index->timestamp.sec;
 470                 o->result.timestamp.nsec = o->src_index->timestamp.nsec;
 471         }
 472         o->merge_size = len;
 473
 474         if (!dfc)
 475                 dfc = xcalloc(1, cache_entry_size(0));
 476         o->df_conflict_entry = dfc;
 477
 478         if (len) {
 479                 const char *prefix = o->prefix ? o->prefix : "";
 480                 struct traverse_info info;
 481
 482                 setup_traverse_info(&info, prefix);
 483                 info.fn = unpack_callback;
 484                 info.data = o;
 485
 486                 if (traverse_trees(len, t, &info) < 0) {
 487                         ret = unpack_failed(o, NULL);
 488                         goto done;
 489                 }
 490         }
 491
 492         /* Any left-over entries in the index? */
 493         if (o->merge) {
 494                 while (o->pos < o->src_index->cache_nr) {
 495                         struct cache_entry *ce = o->src_index->cache[o->pos];
 496                         if (unpack_index_entry(ce, o) < 0) {
 497                                 ret = unpack_failed(o, NULL);
 498                                 goto done;
 499                         }
 500                 }
 501         }
 502
 503         if (o->trivial_merges_only && o->nontrivial_merge) {
 504                 ret = unpack_failed(o, "Merge requires file-level merging");
 505                 goto done;
 506         }
 507
 508         if (!o->skip_sparse_checkout) {
 509                 int empty_worktree = 1;
 510                 for (i = 0;i < o->result.cache_nr;i++) {
 511                         struct cache_entry *ce = o->result.cache[i];
 512
 513                         if (apply_sparse_checkout(ce, o)) {
 514                                 ret = -1;
 515                                 goto done;
 516                         }
 517                         /*
 518                          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
 519                          * area as a result of ce_skip_worktree() shortcuts in
 520                          * verify_absent() and verify_uptodate(). Clear them.
 521                          */
 522                         if (ce_skip_worktree(ce))
 523                                 ce->ce_flags &= ~(CE_UPDATE | CE_REMOVE);
 524                         else
 525                                 empty_worktree = 0;
 526
 527                 }
 528                 if (o->result.cache_nr && empty_worktree) {
 529                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
 530                         goto done;
 531                 }
 532         }
 533
 534         o->src_index = NULL;
 535         ret = check_updates(o) ? (-2) : 0;
 536         if (o->dst_index)
 537                 *o->dst_index = o->result;
 538
 539 done:
 540         for (i = 0;i < el.nr;i++)
 541                 free(el.excludes[i]);
 542         if (el.excludes)
 543                 free(el.excludes);
 544
 545         return ret;
 546 }
 547
 548 /* Here come the merge functions */
 549
 550 static int reject_merge(struct cache_entry *ce, struct unpack_trees_options *o)
 551 {
 552         return error(ERRORMSG(o, would_overwrite), ce->name);
 553 }
 554
 555 static int same(struct cache_entry *a, struct cache_entry *b)
 556 {
 557         if (!!a != !!b)
 558                 return 0;
 559         if (!a && !b)
 560                 return 1;
 561         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
 562                 return 0;
 563         return a->ce_mode == b->ce_mode &&
 564                !hashcmp(a->sha1, b->sha1);
 565 }
 566
 567
 568 /*
 569  * When a CE gets turned into an unmerged entry, we
 570  * want it to be up-to-date
 571  */
 572 static int verify_uptodate_1(struct cache_entry *ce,
 573                                    struct unpack_trees_options *o,
 574                                    const char *error_msg)
 575 {
 576         struct stat st;
 577
 578         if (o->index_only || (!ce_skip_worktree(ce) && (o->reset || ce_uptodate(ce))))
 579                 return 0;
 580
 581         if (!lstat(ce->name, &st)) {
 582                 unsigned changed = ie_match_stat(o->src_index, ce, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
 583                 if (!changed)
 584                         return 0;
 585                 /*
 586                  * NEEDSWORK: the current default policy is to allow
 587                  * submodule to be out of sync wrt the supermodule
 588                  * index.  This needs to be tightened later for
 589                  * submodules that are marked to be automatically
 590                  * checked out.
 591                  */
 592                 if (S_ISGITLINK(ce->ce_mode))
 593                         return 0;
 594                 errno = 0;
 595         }
 596         if (errno == ENOENT)
 597                 return 0;
 598         return o->gently ? -1 :
 599                 error(error_msg, ce->name);
 600 }
 601
 602 static int verify_uptodate(struct cache_entry *ce,
 603                            struct unpack_trees_options *o)
 604 {
 605         if (!o->skip_sparse_checkout && will_have_skip_worktree(ce, o))
 606                 return 0;
 607         return verify_uptodate_1(ce, o, ERRORMSG(o, not_uptodate_file));
 608 }
 609
 610 static int verify_uptodate_sparse(struct cache_entry *ce,
 611                                   struct unpack_trees_options *o)
 612 {
 613         return verify_uptodate_1(ce, o, ERRORMSG(o, sparse_not_uptodate_file));
 614 }
 615
 616 static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
 617 {
 618         if (ce)
 619                 cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
 620 }
 621
 622 /*
 623  * Check that checking out ce->sha1 in subdir ce->name is not
 624  * going to overwrite any working files.
 625  *
 626  * Currently, git does not checkout subprojects during a superproject
 627  * checkout, so it is not going to overwrite anything.
 628  */
 629 static int verify_clean_submodule(struct cache_entry *ce, const char *action,
 630                                       struct unpack_trees_options *o)
 631 {
 632         return 0;
 633 }
 634
 635 static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
 636                                       struct unpack_trees_options *o)
 637 {
 638         /*
 639          * we are about to extract "ce->name"; we would not want to lose
 640          * anything in the existing directory there.
 641          */
 642         int namelen;
 643         int i;
 644         struct dir_struct d;
 645         char *pathbuf;
 646         int cnt = 0;
 647         unsigned char sha1[20];
 648
 649         if (S_ISGITLINK(ce->ce_mode) &&
 650             resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
 651                 /* If we are not going to update the submodule, then
 652                  * we don't care.
 653                  */
 654                 if (!hashcmp(sha1, ce->sha1))
 655                         return 0;
 656                 return verify_clean_submodule(ce, action, o);
 657         }
 658
 659         /*
 660          * First let's make sure we do not have a local modification
 661          * in that directory.
 662          */
 663         namelen = strlen(ce->name);
 664         for (i = o->pos; i < o->src_index->cache_nr; i++) {
 665                 struct cache_entry *ce2 = o->src_index->cache[i];
 666                 int len = ce_namelen(ce2);
 667                 if (len < namelen ||
 668                     strncmp(ce->name, ce2->name, namelen) ||
 669                     ce2->name[namelen] != '/')
 670                         break;
 671                 /*
 672                  * ce2->name is an entry in the subdirectory.
 673                  */
 674                 if (!ce_stage(ce2)) {
 675                         if (verify_uptodate(ce2, o))
 676                                 return -1;
 677                         add_entry(o, ce2, CE_REMOVE, 0);
 678                 }
 679                 cnt++;
 680         }
 681
 682         /*
 683          * Then we need to make sure that we do not lose a locally
 684          * present file that is not ignored.
 685          */
 686         pathbuf = xmalloc(namelen + 2);
 687         memcpy(pathbuf, ce->name, namelen);
 688         strcpy(pathbuf+namelen, "/");
 689
 690         memset(&d, 0, sizeof(d));
 691         if (o->dir)
 692                 d.exclude_per_dir = o->dir->exclude_per_dir;
 693         i = read_directory(&d, pathbuf, namelen+1, NULL);
 694         if (i)
 695                 return o->gently ? -1 :
 696                         error(ERRORMSG(o, not_uptodate_dir), ce->name);
 697         free(pathbuf);
 698         return cnt;
 699 }
 700
 701 /*
 702  * This gets called when there was no index entry for the tree entry 'dst',
 703  * but we found a file in the working tree that 'lstat()' said was fine,
 704  * and we're on a case-insensitive filesystem.
 705  *
 706  * See if we can find a case-insensitive match in the index that also
 707  * matches the stat information, and assume it's that other file!
 708  */
 709 static int icase_exists(struct unpack_trees_options *o, struct cache_entry *dst, struct stat *st)
 710 {
 711         struct cache_entry *src;
 712
 713         src = index_name_exists(o->src_index, dst->name, ce_namelen(dst), 1);
 714         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
 715 }
 716
 717 /*
 718  * We do not want to remove or overwrite a working tree file that
 719  * is not tracked, unless it is ignored.
 720  */
 721 static int verify_absent_1(struct cache_entry *ce, const char *action,
 722                                  struct unpack_trees_options *o,
 723                                  const char *error_msg)
 724 {
 725         struct stat st;
 726
 727         if (o->index_only || o->reset || !o->update)
 728                 return 0;
 729
 730         if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
 731                 return 0;
 732
 733         if (!lstat(ce->name, &st)) {
 734                 int ret;
 735                 int dtype = ce_to_dtype(ce);
 736                 struct cache_entry *result;
 737
 738                 /*
 739                  * It may be that the 'lstat()' succeeded even though
 740                  * target 'ce' was absent, because there is an old
 741                  * entry that is different only in case..
 742                  *
 743                  * Ignore that lstat() if it matches.
 744                  */
 745                 if (ignore_case && icase_exists(o, ce, &st))
 746                         return 0;
 747
 748                 if (o->dir && excluded(o->dir, ce->name, &dtype))
 749                         /*
 750                          * ce->name is explicitly excluded, so it is Ok to
 751                          * overwrite it.
 752                          */
 753                         return 0;
 754                 if (S_ISDIR(st.st_mode)) {
 755                         /*
 756                          * We are checking out path "foo" and
 757                          * found "foo/." in the working tree.
 758                          * This is tricky -- if we have modified
 759                          * files that are in "foo/" we would lose
 760                          * them.
 761                          */
 762                         ret = verify_clean_subdirectory(ce, action, o);
 763                         if (ret < 0)
 764                                 return ret;
 765
 766                         /*
 767                          * If this removed entries from the index,
 768                          * what that means is:
 769                          *
 770                          * (1) the caller unpack_callback() saw path/foo
 771                          * in the index, and it has not removed it because
 772                          * it thinks it is handling 'path' as blob with
 773                          * D/F conflict;
 774                          * (2) we will return "ok, we placed a merged entry
 775                          * in the index" which would cause o->pos to be
 776                          * incremented by one;
 777                          * (3) however, original o->pos now has 'path/foo'
 778                          * marked with "to be removed".
 779                          *
 780                          * We need to increment it by the number of
 781                          * deleted entries here.
 782                          */
 783                         o->pos += ret;
 784                         return 0;
 785                 }
 786
 787                 /*
 788                  * The previous round may already have decided to
 789                  * delete this path, which is in a subdirectory that
 790                  * is being replaced with a blob.
 791                  */
 792                 result = index_name_exists(&o->result, ce->name, ce_namelen(ce), 0);
 793                 if (result) {
 794                         if (result->ce_flags & CE_REMOVE)
 795                                 return 0;
 796                 }
 797
 798                 return o->gently ? -1 :
 799                         error(ERRORMSG(o, would_lose_untracked), ce->name, action);
 800         }
 801         return 0;
 802 }
 803 static int verify_absent(struct cache_entry *ce, const char *action,
 804                          struct unpack_trees_options *o)
 805 {
 806         if (!o->skip_sparse_checkout && will_have_skip_worktree(ce, o))
 807                 return 0;
 808         return verify_absent_1(ce, action, o, ERRORMSG(o, would_lose_untracked));
 809 }
 810
 811 static int verify_absent_sparse(struct cache_entry *ce, const char *action,
 812                          struct unpack_trees_options *o)
 813 {
 814         return verify_absent_1(ce, action, o, ERRORMSG(o, would_lose_orphaned));
 815 }
 816
 817 static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 818                 struct unpack_trees_options *o)
 819 {
 820         int update = CE_UPDATE;
 821
 822         if (!old) {
 823                 if (verify_absent(merge, "overwritten", o))
 824                         return -1;
 825                 invalidate_ce_path(merge, o);
 826         } else if (!(old->ce_flags & CE_CONFLICTED)) {
 827                 /*
 828                  * See if we can re-use the old CE directly?
 829                  * That way we get the uptodate stat info.
 830                  *
 831                  * This also removes the UPDATE flag on a match; otherwise
 832                  * we will end up overwriting local changes in the work tree.
 833                  */
 834                 if (same(old, merge)) {
 835                         copy_cache_entry(merge, old);
 836                         update = 0;
 837                 } else {
 838                         if (verify_uptodate(old, o))
 839                                 return -1;
 840                         if (ce_skip_worktree(old))
 841                                 update |= CE_SKIP_WORKTREE;
 842                         invalidate_ce_path(old, o);
 843                 }
 844         } else {
 845                 /*
 846                  * Previously unmerged entry left as an existence
 847                  * marker by read_index_unmerged();
 848                  */
 849                 invalidate_ce_path(old, o);
 850         }
 851
 852         add_entry(o, merge, update, CE_STAGEMASK);
 853         return 1;
 854 }
 855
 856 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
 857                 struct unpack_trees_options *o)
 858 {
 859         /* Did it exist in the index? */
 860         if (!old) {
 861                 if (verify_absent(ce, "removed", o))
 862                         return -1;
 863                 return 0;
 864         }
 865         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
 866                 return -1;
 867         add_entry(o, ce, CE_REMOVE, 0);
 868         invalidate_ce_path(ce, o);
 869         return 1;
 870 }
 871
 872 static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
 873 {
 874         add_entry(o, ce, 0, 0);
 875         return 1;
 876 }
 877
 878 #if DBRT_DEBUG
 879 static void show_stage_entry(FILE *o,
 880                              const char *label, const struct cache_entry *ce)
 881 {
 882         if (!ce)
 883                 fprintf(o, "%s (missing)\n", label);
 884         else
 885                 fprintf(o, "%s%06o %s %d\t%s\n",
 886                         label,
 887                         ce->ce_mode,
 888                         sha1_to_hex(ce->sha1),
 889                         ce_stage(ce),
 890                         ce->name);
 891 }
 892 #endif
 893
 894 int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
 895 {
 896         struct cache_entry *index;
 897         struct cache_entry *head;
 898         struct cache_entry *remote = stages[o->head_idx + 1];
 899         int count;
 900         int head_match = 0;
 901         int remote_match = 0;
 902
 903         int df_conflict_head = 0;
 904         int df_conflict_remote = 0;
 905
 906         int any_anc_missing = 0;
 907         int no_anc_exists = 1;
 908         int i;
 909
 910         for (i = 1; i < o->head_idx; i++) {
 911                 if (!stages[i] || stages[i] == o->df_conflict_entry)
 912                         any_anc_missing = 1;
 913                 else
 914                         no_anc_exists = 0;
 915         }
 916
 917         index = stages[0];
 918         head = stages[o->head_idx];
 919
 920         if (head == o->df_conflict_entry) {
 921                 df_conflict_head = 1;
 922                 head = NULL;
 923         }
 924
 925         if (remote == o->df_conflict_entry) {
 926                 df_conflict_remote = 1;
 927                 remote = NULL;
 928         }
 929
 930         /* First, if there's a #16 situation, note that to prevent #13
 931          * and #14.
 932          */
 933         if (!same(remote, head)) {
 934                 for (i = 1; i < o->head_idx; i++) {
 935                         if (same(stages[i], head)) {
 936                                 head_match = i;
 937                         }
 938                         if (same(stages[i], remote)) {
 939                                 remote_match = i;
 940                         }
 941                 }
 942         }
 943
 944         /* We start with cases where the index is allowed to match
 945          * something other than the head: #14(ALT) and #2ALT, where it
 946          * is permitted to match the result instead.
 947          */
 948         /* #14, #14ALT, #2ALT */
 949         if (remote && !df_conflict_head && head_match && !remote_match) {
 950                 if (index && !same(index, remote) && !same(index, head))
 951                         return o->gently ? -1 : reject_merge(index, o);
 952                 return merged_entry(remote, index, o);
 953         }
 954         /*
 955          * If we have an entry in the index cache, then we want to
 956          * make sure that it matches head.
 957          */
 958         if (index && !same(index, head))
 959                 return o->gently ? -1 : reject_merge(index, o);
 960
 961         if (head) {
 962                 /* #5ALT, #15 */
 963                 if (same(head, remote))
 964                         return merged_entry(head, index, o);
 965                 /* #13, #3ALT */
 966                 if (!df_conflict_remote && remote_match && !head_match)
 967                         return merged_entry(head, index, o);
 968         }
 969
 970         /* #1 */
 971         if (!head && !remote && any_anc_missing)
 972                 return 0;
 973
 974         /* Under the new "aggressive" rule, we resolve mostly trivial
 975          * cases that we historically had git-merge-one-file resolve.
 976          */
 977         if (o->aggressive) {
 978                 int head_deleted = !head && !df_conflict_head;
 979                 int remote_deleted = !remote && !df_conflict_remote;
 980                 struct cache_entry *ce = NULL;
 981
 982                 if (index)
 983                         ce = index;
 984                 else if (head)
 985                         ce = head;
 986                 else if (remote)
 987                         ce = remote;
 988                 else {
 989                         for (i = 1; i < o->head_idx; i++) {
 990                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
 991                                         ce = stages[i];
 992                                         break;
 993                                 }
 994                         }
 995                 }
 996
 997                 /*
 998                  * Deleted in both.
 999                  * Deleted in one and unchanged in the other.
1000                  */
1001                 if ((head_deleted && remote_deleted) ||
1002                     (head_deleted && remote && remote_match) ||
1003                     (remote_deleted && head && head_match)) {
1004                         if (index)
1005                                 return deleted_entry(index, index, o);
1006                         if (ce && !head_deleted) {
1007                                 if (verify_absent(ce, "removed", o))
1008                                         return -1;
1009                         }
1010                         return 0;
1011                 }
1012                 /*
1013                  * Added in both, identically.
1014                  */
1015                 if (no_anc_exists && head && remote && same(head, remote))
1016                         return merged_entry(head, index, o);
1017
1018         }
1019
1020         /* Below are "no merge" cases, which require that the index be
1021          * up-to-date to avoid the files getting overwritten with
1022          * conflict resolution files.
1023          */
1024         if (index) {
1025                 if (verify_uptodate(index, o))
1026                         return -1;
1027         }
1028
1029         o->nontrivial_merge = 1;
1030
1031         /* #2, #3, #4, #6, #7, #9, #10, #11. */
1032         count = 0;
1033         if (!head_match || !remote_match) {
1034                 for (i = 1; i < o->head_idx; i++) {
1035                         if (stages[i] && stages[i] != o->df_conflict_entry) {
1036                                 keep_entry(stages[i], o);
1037                                 count++;
1038                                 break;
1039                         }
1040                 }
1041         }
1042 #if DBRT_DEBUG
1043         else {
1044                 fprintf(stderr, "read-tree: warning #16 detected\n");
1045                 show_stage_entry(stderr, "head   ", stages[head_match]);
1046                 show_stage_entry(stderr, "remote ", stages[remote_match]);
1047         }
1048 #endif
1049         if (head) { count += keep_entry(head, o); }
1050         if (remote) { count += keep_entry(remote, o); }
1051         return count;
1052 }
1053
1054 /*
1055  * Two-way merge.
1056  *
1057  * The rule is to "carry forward" what is in the index without losing
1058  * information across a "fast-forward", favoring a successful merge
1059  * over a merge failure when it makes sense.  For details of the
1060  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
1061  *
1062  */
1063 int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1064 {
1065         struct cache_entry *current = src[0];
1066         struct cache_entry *oldtree = src[1];
1067         struct cache_entry *newtree = src[2];
1068
1069         if (o->merge_size != 2)
1070                 return error("Cannot do a twoway merge of %d trees",
1071                              o->merge_size);
1072
1073         if (oldtree == o->df_conflict_entry)
1074                 oldtree = NULL;
1075         if (newtree == o->df_conflict_entry)
1076                 newtree = NULL;
1077
1078         if (current) {
1079                 if ((!oldtree && !newtree) || /* 4 and 5 */
1080                     (!oldtree && newtree &&
1081                      same(current, newtree)) || /* 6 and 7 */
1082                     (oldtree && newtree &&
1083                      same(oldtree, newtree)) || /* 14 and 15 */
1084                     (oldtree && newtree &&
1085                      !same(oldtree, newtree) && /* 18 and 19 */
1086                      same(current, newtree))) {
1087                         return keep_entry(current, o);
1088                 }
1089                 else if (oldtree && !newtree && same(current, oldtree)) {
1090                         /* 10 or 11 */
1091                         return deleted_entry(oldtree, current, o);
1092                 }
1093                 else if (oldtree && newtree &&
1094                          same(current, oldtree) && !same(current, newtree)) {
1095                         /* 20 or 21 */
1096                         return merged_entry(newtree, current, o);
1097                 }
1098                 else {
1099                         /* all other failures */
1100                         if (oldtree)
1101                                 return o->gently ? -1 : reject_merge(oldtree, o);
1102                         if (current)
1103                                 return o->gently ? -1 : reject_merge(current, o);
1104                         if (newtree)
1105                                 return o->gently ? -1 : reject_merge(newtree, o);
1106                         return -1;
1107                 }
1108         }
1109         else if (newtree) {
1110                 if (oldtree && !o->initial_checkout) {
1111                         /*
1112                          * deletion of the path was staged;
1113                          */
1114                         if (same(oldtree, newtree))
1115                                 return 1;
1116                         return reject_merge(oldtree, o);
1117                 }
1118                 return merged_entry(newtree, current, o);
1119         }
1120         return deleted_entry(oldtree, current, o);
1121 }
1122
1123 /*
1124  * Bind merge.
1125  *
1126  * Keep the index entries at stage0, collapse stage1 but make sure
1127  * stage0 does not have anything there.
1128  */
1129 int bind_merge(struct cache_entry **src,
1130                 struct unpack_trees_options *o)
1131 {
1132         struct cache_entry *old = src[0];
1133         struct cache_entry *a = src[1];
1134
1135         if (o->merge_size != 1)
1136                 return error("Cannot do a bind merge of %d trees\n",
1137                              o->merge_size);
1138         if (a && old)
1139                 return o->gently ? -1 :
1140                         error(ERRORMSG(o, bind_overlap), a->name, old->name);
1141         if (!a)
1142                 return keep_entry(old, o);
1143         else
1144                 return merged_entry(a, NULL, o);
1145 }
1146
1147 /*
1148  * One-way merge.
1149  *
1150  * The rule is:
1151  * - take the stat information from stage0, take the data from stage1
1152  */
1153 int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1154 {
1155         struct cache_entry *old = src[0];
1156         struct cache_entry *a = src[1];
1157
1158         if (o->merge_size != 1)
1159                 return error("Cannot do a oneway merge of %d trees",
1160                              o->merge_size);
1161
1162         if (!a || a == o->df_conflict_entry)
1163                 return deleted_entry(old, old, o);
1164
1165         if (old && same(old, a)) {
1166                 int update = 0;
1167                 if (o->reset && !ce_uptodate(old) && !ce_skip_worktree(old)) {
1168                         struct stat st;
1169                         if (lstat(old->name, &st) ||
1170                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
1171                                 update |= CE_UPDATE;
1172                 }
1173                 add_entry(o, old, update, 0);
1174                 return 0;
1175         }
1176         return merged_entry(a, old, o);
1177 }