unpack-trees.c

   1 #define NO_THE_INDEX_COMPATIBILITY_MACROS
   2 #include "cache.h"
   3 #include "repository.h"
   4 #include "config.h"
   5 #include "dir.h"
   6 #include "tree.h"
   7 #include "tree-walk.h"
   8 #include "cache-tree.h"
   9 #include "unpack-trees.h"
  10 #include "progress.h"
  11 #include "refs.h"
  12 #include "attr.h"
  13 #include "split-index.h"
  14 #include "dir.h"
  15 #include "submodule.h"
  16 #include "submodule-config.h"
  17
  18 /*
  19  * Error messages expected by scripts out of plumbing commands such as
  20  * read-tree.  Non-scripted Porcelain is not required to use these messages
  21  * and in fact are encouraged to reword them to better suit their particular
  22  * situation better.  See how "git checkout" and "git merge" replaces
  23  * them using setup_unpack_trees_porcelain(), for example.
  24  */
  25 static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
  26         /* ERROR_WOULD_OVERWRITE */
  27         "Entry '%s' would be overwritten by merge. Cannot merge.",
  28
  29         /* ERROR_NOT_UPTODATE_FILE */
  30         "Entry '%s' not uptodate. Cannot merge.",
  31
  32         /* ERROR_NOT_UPTODATE_DIR */
  33         "Updating '%s' would lose untracked files in it",
  34
  35         /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
  36         "Untracked working tree file '%s' would be overwritten by merge.",
  37
  38         /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
  39         "Untracked working tree file '%s' would be removed by merge.",
  40
  41         /* ERROR_BIND_OVERLAP */
  42         "Entry '%s' overlaps with '%s'.  Cannot bind.",
  43
  44         /* ERROR_SPARSE_NOT_UPTODATE_FILE */
  45         "Entry '%s' not uptodate. Cannot update sparse checkout.",
  46
  47         /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
  48         "Working tree file '%s' would be overwritten by sparse checkout update.",
  49
  50         /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
  51         "Working tree file '%s' would be removed by sparse checkout update.",
  52
  53         /* ERROR_WOULD_LOSE_SUBMODULE */
  54         "Submodule '%s' cannot checkout new HEAD.",
  55 };
  56
  57 #define ERRORMSG(o,type) \
  58         ( ((o) && (o)->msgs[(type)]) \
  59           ? ((o)->msgs[(type)])      \
  60           : (unpack_plumbing_errors[(type)]) )
  61
  62 static const char *super_prefixed(const char *path)
  63 {
  64         /*
  65          * It is necessary and sufficient to have two static buffers
  66          * here, as the return value of this function is fed to
  67          * error() using the unpack_*_errors[] templates we see above.
  68          */
  69         static struct strbuf buf[2] = {STRBUF_INIT, STRBUF_INIT};
  70         static int super_prefix_len = -1;
  71         static unsigned idx = ARRAY_SIZE(buf) - 1;
  72
  73         if (super_prefix_len < 0) {
  74                 const char *super_prefix = get_super_prefix();
  75                 if (!super_prefix) {
  76                         super_prefix_len = 0;
  77                 } else {
  78                         int i;
  79                         for (i = 0; i < ARRAY_SIZE(buf); i++)
  80                                 strbuf_addstr(&buf[i], super_prefix);
  81                         super_prefix_len = buf[0].len;
  82                 }
  83         }
  84
  85         if (!super_prefix_len)
  86                 return path;
  87
  88         if (++idx >= ARRAY_SIZE(buf))
  89                 idx = 0;
  90
  91         strbuf_setlen(&buf[idx], super_prefix_len);
  92         strbuf_addstr(&buf[idx], path);
  93
  94         return buf[idx].buf;
  95 }
  96
  97 void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
  98                                   const char *cmd)
  99 {
 100         int i;
 101         const char **msgs = opts->msgs;
 102         const char *msg;
 103
 104         if (!strcmp(cmd, "checkout"))
 105                 msg = advice_commit_before_merge
 106                       ? _("Your local changes to the following files would be overwritten by checkout:\n%%s"
 107                           "Please commit your changes or stash them before you switch branches.")
 108                       : _("Your local changes to the following files would be overwritten by checkout:\n%%s");
 109         else if (!strcmp(cmd, "merge"))
 110                 msg = advice_commit_before_merge
 111                       ? _("Your local changes to the following files would be overwritten by merge:\n%%s"
 112                           "Please commit your changes or stash them before you merge.")
 113                       : _("Your local changes to the following files would be overwritten by merge:\n%%s");
 114         else
 115                 msg = advice_commit_before_merge
 116                       ? _("Your local changes to the following files would be overwritten by %s:\n%%s"
 117                           "Please commit your changes or stash them before you %s.")
 118                       : _("Your local changes to the following files would be overwritten by %s:\n%%s");
 119         msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
 120                 xstrfmt(msg, cmd, cmd);
 121
 122         msgs[ERROR_NOT_UPTODATE_DIR] =
 123                 _("Updating the following directories would lose untracked files in them:\n%s");
 124
 125         if (!strcmp(cmd, "checkout"))
 126                 msg = advice_commit_before_merge
 127                       ? _("The following untracked working tree files would be removed by checkout:\n%%s"
 128                           "Please move or remove them before you switch branches.")
 129                       : _("The following untracked working tree files would be removed by checkout:\n%%s");
 130         else if (!strcmp(cmd, "merge"))
 131                 msg = advice_commit_before_merge
 132                       ? _("The following untracked working tree files would be removed by merge:\n%%s"
 133                           "Please move or remove them before you merge.")
 134                       : _("The following untracked working tree files would be removed by merge:\n%%s");
 135         else
 136                 msg = advice_commit_before_merge
 137                       ? _("The following untracked working tree files would be removed by %s:\n%%s"
 138                           "Please move or remove them before you %s.")
 139                       : _("The following untracked working tree files would be removed by %s:\n%%s");
 140         msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] = xstrfmt(msg, cmd, cmd);
 141
 142         if (!strcmp(cmd, "checkout"))
 143                 msg = advice_commit_before_merge
 144                       ? _("The following untracked working tree files would be overwritten by checkout:\n%%s"
 145                           "Please move or remove them before you switch branches.")
 146                       : _("The following untracked working tree files would be overwritten by checkout:\n%%s");
 147         else if (!strcmp(cmd, "merge"))
 148                 msg = advice_commit_before_merge
 149                       ? _("The following untracked working tree files would be overwritten by merge:\n%%s"
 150                           "Please move or remove them before you merge.")
 151                       : _("The following untracked working tree files would be overwritten by merge:\n%%s");
 152         else
 153                 msg = advice_commit_before_merge
 154                       ? _("The following untracked working tree files would be overwritten by %s:\n%%s"
 155                           "Please move or remove them before you %s.")
 156                       : _("The following untracked working tree files would be overwritten by %s:\n%%s");
 157         msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] = xstrfmt(msg, cmd, cmd);
 158
 159         /*
 160          * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
 161          * cannot easily display it as a list.
 162          */
 163         msgs[ERROR_BIND_OVERLAP] = _("Entry '%s' overlaps with '%s'.  Cannot bind.");
 164
 165         msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
 166                 _("Cannot update sparse checkout: the following entries are not up to date:\n%s");
 167         msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
 168                 _("The following working tree files would be overwritten by sparse checkout update:\n%s");
 169         msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
 170                 _("The following working tree files would be removed by sparse checkout update:\n%s");
 171         msgs[ERROR_WOULD_LOSE_SUBMODULE] =
 172                 _("Cannot update submodule:\n%s");
 173
 174         opts->show_all_errors = 1;
 175         /* rejected paths may not have a static buffer */
 176         for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
 177                 opts->unpack_rejects[i].strdup_strings = 1;
 178 }
 179
 180 static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
 181                          unsigned int set, unsigned int clear)
 182 {
 183         clear |= CE_HASHED;
 184
 185         if (set & CE_REMOVE)
 186                 set |= CE_WT_REMOVE;
 187
 188         ce->ce_flags = (ce->ce_flags & ~clear) | set;
 189         return add_index_entry(&o->result, ce,
 190                                ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 191 }
 192
 193 static struct cache_entry *dup_entry(const struct cache_entry *ce)
 194 {
 195         unsigned int size = ce_size(ce);
 196         struct cache_entry *new = xmalloc(size);
 197
 198         memcpy(new, ce, size);
 199         return new;
 200 }
 201
 202 static void add_entry(struct unpack_trees_options *o,
 203                       const struct cache_entry *ce,
 204                       unsigned int set, unsigned int clear)
 205 {
 206         do_add_entry(o, dup_entry(ce), set, clear);
 207 }
 208
 209 /*
 210  * add error messages on path <path>
 211  * corresponding to the type <e> with the message <msg>
 212  * indicating if it should be display in porcelain or not
 213  */
 214 static int add_rejected_path(struct unpack_trees_options *o,
 215                              enum unpack_trees_error_types e,
 216                              const char *path)
 217 {
 218         if (!o->show_all_errors)
 219                 return error(ERRORMSG(o, e), super_prefixed(path));
 220
 221         /*
 222          * Otherwise, insert in a list for future display by
 223          * display_error_msgs()
 224          */
 225         string_list_append(&o->unpack_rejects[e], path);
 226         return -1;
 227 }
 228
 229 /*
 230  * display all the error messages stored in a nice way
 231  */
 232 static void display_error_msgs(struct unpack_trees_options *o)
 233 {
 234         int e, i;
 235         int something_displayed = 0;
 236         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
 237                 struct string_list *rejects = &o->unpack_rejects[e];
 238                 if (rejects->nr > 0) {
 239                         struct strbuf path = STRBUF_INIT;
 240                         something_displayed = 1;
 241                         for (i = 0; i < rejects->nr; i++)
 242                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
 243                         error(ERRORMSG(o, e), super_prefixed(path.buf));
 244                         strbuf_release(&path);
 245                 }
 246                 string_list_clear(rejects, 0);
 247         }
 248         if (something_displayed)
 249                 fprintf(stderr, _("Aborting\n"));
 250 }
 251
 252 static int check_submodule_move_head(const struct cache_entry *ce,
 253                                      const char *old_id,
 254                                      const char *new_id,
 255                                      struct unpack_trees_options *o)
 256 {
 257         unsigned flags = SUBMODULE_MOVE_HEAD_DRY_RUN;
 258         const struct submodule *sub = submodule_from_ce(ce);
 259
 260         if (!sub)
 261                 return 0;
 262
 263         if (o->reset)
 264                 flags |= SUBMODULE_MOVE_HEAD_FORCE;
 265
 266         if (submodule_move_head(ce->name, old_id, new_id, flags))
 267                 return o->gently ? -1 :
 268                                    add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
 269         return 0;
 270 }
 271
 272 /*
 273  * Preform the loading of the repository's gitmodules file.  This function is
 274  * used by 'check_update()' to perform loading of the gitmodules file in two
 275  * differnt situations:
 276  * (1) before removing entries from the working tree if the gitmodules file has
 277  *     been marked for removal.  This situation is specified by 'state' == NULL.
 278  * (2) before checking out entries to the working tree if the gitmodules file
 279  *     has been marked for update.  This situation is specified by 'state' != NULL.
 280  */
 281 static void load_gitmodules_file(struct index_state *index,
 282                                  struct checkout *state)
 283 {
 284         int pos = index_name_pos(index, GITMODULES_FILE, strlen(GITMODULES_FILE));
 285
 286         if (pos >= 0) {
 287                 struct cache_entry *ce = index->cache[pos];
 288                 if (!state && ce->ce_flags & CE_WT_REMOVE) {
 289                         repo_read_gitmodules(the_repository);
 290                 } else if (state && (ce->ce_flags & CE_UPDATE)) {
 291                         submodule_free();
 292                         checkout_entry(ce, state, NULL);
 293                         repo_read_gitmodules(the_repository);
 294                 }
 295         }
 296 }
 297
 298 /*
 299  * Unlink the last component and schedule the leading directories for
 300  * removal, such that empty directories get removed.
 301  */
 302 static void unlink_entry(const struct cache_entry *ce)
 303 {
 304         const struct submodule *sub = submodule_from_ce(ce);
 305         if (sub) {
 306                 /* state.force is set at the caller. */
 307                 submodule_move_head(ce->name, "HEAD", NULL,
 308                                     SUBMODULE_MOVE_HEAD_FORCE);
 309         }
 310         if (!check_leading_path(ce->name, ce_namelen(ce)))
 311                 return;
 312         if (remove_or_warn(ce->ce_mode, ce->name))
 313                 return;
 314         schedule_dir_for_removal(ce->name, ce_namelen(ce));
 315 }
 316
 317 static struct progress *get_progress(struct unpack_trees_options *o)
 318 {
 319         unsigned cnt = 0, total = 0;
 320         struct index_state *index = &o->result;
 321
 322         if (!o->update || !o->verbose_update)
 323                 return NULL;
 324
 325         for (; cnt < index->cache_nr; cnt++) {
 326                 const struct cache_entry *ce = index->cache[cnt];
 327                 if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
 328                         total++;
 329         }
 330
 331         return start_delayed_progress(_("Checking out files"), total);
 332 }
 333
 334 static int check_updates(struct unpack_trees_options *o)
 335 {
 336         unsigned cnt = 0;
 337         int errs = 0;
 338         struct progress *progress = NULL;
 339         struct index_state *index = &o->result;
 340         struct checkout state = CHECKOUT_INIT;
 341         int i;
 342
 343         state.force = 1;
 344         state.quiet = 1;
 345         state.refresh_cache = 1;
 346         state.istate = index;
 347
 348         progress = get_progress(o);
 349
 350         if (o->update)
 351                 git_attr_set_direction(GIT_ATTR_CHECKOUT, index);
 352
 353         if (should_update_submodules() && o->update && !o->dry_run)
 354                 load_gitmodules_file(index, NULL);
 355
 356         for (i = 0; i < index->cache_nr; i++) {
 357                 const struct cache_entry *ce = index->cache[i];
 358
 359                 if (ce->ce_flags & CE_WT_REMOVE) {
 360                         display_progress(progress, ++cnt);
 361                         if (o->update && !o->dry_run)
 362                                 unlink_entry(ce);
 363                 }
 364         }
 365         remove_marked_cache_entries(index);
 366         remove_scheduled_dirs();
 367
 368         if (should_update_submodules() && o->update && !o->dry_run)
 369                 load_gitmodules_file(index, &state);
 370
 371         enable_delayed_checkout(&state);
 372         for (i = 0; i < index->cache_nr; i++) {
 373                 struct cache_entry *ce = index->cache[i];
 374
 375                 if (ce->ce_flags & CE_UPDATE) {
 376                         if (ce->ce_flags & CE_WT_REMOVE)
 377                                 die("BUG: both update and delete flags are set on %s",
 378                                     ce->name);
 379                         display_progress(progress, ++cnt);
 380                         ce->ce_flags &= ~CE_UPDATE;
 381                         if (o->update && !o->dry_run) {
 382                                 errs |= checkout_entry(ce, &state, NULL);
 383                         }
 384                 }
 385         }
 386         stop_progress(&progress);
 387         errs |= finish_delayed_checkout(&state);
 388         if (o->update)
 389                 git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
 390         return errs != 0;
 391 }
 392
 393 static int verify_uptodate_sparse(const struct cache_entry *ce,
 394                                   struct unpack_trees_options *o);
 395 static int verify_absent_sparse(const struct cache_entry *ce,
 396                                 enum unpack_trees_error_types,
 397                                 struct unpack_trees_options *o);
 398
 399 static int apply_sparse_checkout(struct index_state *istate,
 400                                  struct cache_entry *ce,
 401                                  struct unpack_trees_options *o)
 402 {
 403         int was_skip_worktree = ce_skip_worktree(ce);
 404
 405         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
 406                 ce->ce_flags |= CE_SKIP_WORKTREE;
 407         else
 408                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
 409         if (was_skip_worktree != ce_skip_worktree(ce)) {
 410                 ce->ce_flags |= CE_UPDATE_IN_BASE;
 411                 istate->cache_changed |= CE_ENTRY_CHANGED;
 412         }
 413
 414         /*
 415          * if (!was_skip_worktree && !ce_skip_worktree()) {
 416          *      This is perfectly normal. Move on;
 417          * }
 418          */
 419
 420         /*
 421          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
 422          * area as a result of ce_skip_worktree() shortcuts in
 423          * verify_absent() and verify_uptodate().
 424          * Make sure they don't modify worktree if they are already
 425          * outside checkout area
 426          */
 427         if (was_skip_worktree && ce_skip_worktree(ce)) {
 428                 ce->ce_flags &= ~CE_UPDATE;
 429
 430                 /*
 431                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
 432                  * on to get that file removed from both index and worktree.
 433                  * If that file is already outside worktree area, don't
 434                  * bother remove it.
 435                  */
 436                 if (ce->ce_flags & CE_REMOVE)
 437                         ce->ce_flags &= ~CE_WT_REMOVE;
 438         }
 439
 440         if (!was_skip_worktree && ce_skip_worktree(ce)) {
 441                 /*
 442                  * If CE_UPDATE is set, verify_uptodate() must be called already
 443                  * also stat info may have lost after merged_entry() so calling
 444                  * verify_uptodate() again may fail
 445                  */
 446                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
 447                         return -1;
 448                 ce->ce_flags |= CE_WT_REMOVE;
 449                 ce->ce_flags &= ~CE_UPDATE;
 450         }
 451         if (was_skip_worktree && !ce_skip_worktree(ce)) {
 452                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
 453                         return -1;
 454                 ce->ce_flags |= CE_UPDATE;
 455         }
 456         return 0;
 457 }
 458
 459 static inline int call_unpack_fn(const struct cache_entry * const *src,
 460                                  struct unpack_trees_options *o)
 461 {
 462         int ret = o->fn(src, o);
 463         if (ret > 0)
 464                 ret = 0;
 465         return ret;
 466 }
 467
 468 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
 469 {
 470         ce->ce_flags |= CE_UNPACKED;
 471
 472         if (o->cache_bottom < o->src_index->cache_nr &&
 473             o->src_index->cache[o->cache_bottom] == ce) {
 474                 int bottom = o->cache_bottom;
 475                 while (bottom < o->src_index->cache_nr &&
 476                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
 477                         bottom++;
 478                 o->cache_bottom = bottom;
 479         }
 480 }
 481
 482 static void mark_all_ce_unused(struct index_state *index)
 483 {
 484         int i;
 485         for (i = 0; i < index->cache_nr; i++)
 486                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
 487 }
 488
 489 static int locate_in_src_index(const struct cache_entry *ce,
 490                                struct unpack_trees_options *o)
 491 {
 492         struct index_state *index = o->src_index;
 493         int len = ce_namelen(ce);
 494         int pos = index_name_pos(index, ce->name, len);
 495         if (pos < 0)
 496                 pos = -1 - pos;
 497         return pos;
 498 }
 499
 500 /*
 501  * We call unpack_index_entry() with an unmerged cache entry
 502  * only in diff-index, and it wants a single callback.  Skip
 503  * the other unmerged entry with the same name.
 504  */
 505 static void mark_ce_used_same_name(struct cache_entry *ce,
 506                                    struct unpack_trees_options *o)
 507 {
 508         struct index_state *index = o->src_index;
 509         int len = ce_namelen(ce);
 510         int pos;
 511
 512         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
 513                 struct cache_entry *next = index->cache[pos];
 514                 if (len != ce_namelen(next) ||
 515                     memcmp(ce->name, next->name, len))
 516                         break;
 517                 mark_ce_used(next, o);
 518         }
 519 }
 520
 521 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
 522 {
 523         const struct index_state *index = o->src_index;
 524         int pos = o->cache_bottom;
 525
 526         while (pos < index->cache_nr) {
 527                 struct cache_entry *ce = index->cache[pos];
 528                 if (!(ce->ce_flags & CE_UNPACKED))
 529                         return ce;
 530                 pos++;
 531         }
 532         return NULL;
 533 }
 534
 535 static void add_same_unmerged(const struct cache_entry *ce,
 536                               struct unpack_trees_options *o)
 537 {
 538         struct index_state *index = o->src_index;
 539         int len = ce_namelen(ce);
 540         int pos = index_name_pos(index, ce->name, len);
 541
 542         if (0 <= pos)
 543                 die("programming error in a caller of mark_ce_used_same_name");
 544         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
 545                 struct cache_entry *next = index->cache[pos];
 546                 if (len != ce_namelen(next) ||
 547                     memcmp(ce->name, next->name, len))
 548                         break;
 549                 add_entry(o, next, 0, 0);
 550                 mark_ce_used(next, o);
 551         }
 552 }
 553
 554 static int unpack_index_entry(struct cache_entry *ce,
 555                               struct unpack_trees_options *o)
 556 {
 557         const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 558         int ret;
 559
 560         src[0] = ce;
 561
 562         mark_ce_used(ce, o);
 563         if (ce_stage(ce)) {
 564                 if (o->skip_unmerged) {
 565                         add_entry(o, ce, 0, 0);
 566                         return 0;
 567                 }
 568         }
 569         ret = call_unpack_fn(src, o);
 570         if (ce_stage(ce))
 571                 mark_ce_used_same_name(ce, o);
 572         return ret;
 573 }
 574
 575 static int find_cache_pos(struct traverse_info *, const struct name_entry *);
 576
 577 static void restore_cache_bottom(struct traverse_info *info, int bottom)
 578 {
 579         struct unpack_trees_options *o = info->data;
 580
 581         if (o->diff_index_cached)
 582                 return;
 583         o->cache_bottom = bottom;
 584 }
 585
 586 static int switch_cache_bottom(struct traverse_info *info)
 587 {
 588         struct unpack_trees_options *o = info->data;
 589         int ret, pos;
 590
 591         if (o->diff_index_cached)
 592                 return 0;
 593         ret = o->cache_bottom;
 594         pos = find_cache_pos(info->prev, &info->name);
 595
 596         if (pos < -1)
 597                 o->cache_bottom = -2 - pos;
 598         else if (pos < 0)
 599                 o->cache_bottom = o->src_index->cache_nr;
 600         return ret;
 601 }
 602
 603 static inline int are_same_oid(struct name_entry *name_j, struct name_entry *name_k)
 604 {
 605         return name_j->oid && name_k->oid && !oidcmp(name_j->oid, name_k->oid);
 606 }
 607
 608 static int traverse_trees_recursive(int n, unsigned long dirmask,
 609                                     unsigned long df_conflicts,
 610                                     struct name_entry *names,
 611                                     struct traverse_info *info)
 612 {
 613         int i, ret, bottom;
 614         int nr_buf = 0;
 615         struct tree_desc t[MAX_UNPACK_TREES];
 616         void *buf[MAX_UNPACK_TREES];
 617         struct traverse_info newinfo;
 618         struct name_entry *p;
 619
 620         p = names;
 621         while (!p->mode)
 622                 p++;
 623
 624         newinfo = *info;
 625         newinfo.prev = info;
 626         newinfo.pathspec = info->pathspec;
 627         newinfo.name = *p;
 628         newinfo.pathlen += tree_entry_len(p) + 1;
 629         newinfo.df_conflicts |= df_conflicts;
 630
 631         /*
 632          * Fetch the tree from the ODB for each peer directory in the
 633          * n commits.
 634          *
 635          * For 2- and 3-way traversals, we try to avoid hitting the
 636          * ODB twice for the same OID.  This should yield a nice speed
 637          * up in checkouts and merges when the commits are similar.
 638          *
 639          * We don't bother doing the full O(n^2) search for larger n,
 640          * because wider traversals don't happen that often and we
 641          * avoid the search setup.
 642          *
 643          * When 2 peer OIDs are the same, we just copy the tree
 644          * descriptor data.  This implicitly borrows the buffer
 645          * data from the earlier cell.
 646          */
 647         for (i = 0; i < n; i++, dirmask >>= 1) {
 648                 if (i > 0 && are_same_oid(&names[i], &names[i - 1]))
 649                         t[i] = t[i - 1];
 650                 else if (i > 1 && are_same_oid(&names[i], &names[i - 2]))
 651                         t[i] = t[i - 2];
 652                 else {
 653                         const struct object_id *oid = NULL;
 654                         if (dirmask & 1)
 655                                 oid = names[i].oid;
 656                         buf[nr_buf++] = fill_tree_descriptor(t + i, oid);
 657                 }
 658         }
 659
 660         bottom = switch_cache_bottom(&newinfo);
 661         ret = traverse_trees(n, t, &newinfo);
 662         restore_cache_bottom(&newinfo, bottom);
 663
 664         for (i = 0; i < nr_buf; i++)
 665                 free(buf[i]);
 666
 667         return ret;
 668 }
 669
 670 /*
 671  * Compare the traverse-path to the cache entry without actually
 672  * having to generate the textual representation of the traverse
 673  * path.
 674  *
 675  * NOTE! This *only* compares up to the size of the traverse path
 676  * itself - the caller needs to do the final check for the cache
 677  * entry having more data at the end!
 678  */
 679 static int do_compare_entry_piecewise(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 680 {
 681         int len, pathlen, ce_len;
 682         const char *ce_name;
 683
 684         if (info->prev) {
 685                 int cmp = do_compare_entry_piecewise(ce, info->prev,
 686                                                      &info->name);
 687                 if (cmp)
 688                         return cmp;
 689         }
 690         pathlen = info->pathlen;
 691         ce_len = ce_namelen(ce);
 692
 693         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 694         if (ce_len < pathlen)
 695                 return -1;
 696
 697         ce_len -= pathlen;
 698         ce_name = ce->name + pathlen;
 699
 700         len = tree_entry_len(n);
 701         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 702 }
 703
 704 static int do_compare_entry(const struct cache_entry *ce,
 705                             const struct traverse_info *info,
 706                             const struct name_entry *n)
 707 {
 708         int len, pathlen, ce_len;
 709         const char *ce_name;
 710         int cmp;
 711
 712         /*
 713          * If we have not precomputed the traverse path, it is quicker
 714          * to avoid doing so.  But if we have precomputed it,
 715          * it is quicker to use the precomputed version.
 716          */
 717         if (!info->traverse_path)
 718                 return do_compare_entry_piecewise(ce, info, n);
 719
 720         cmp = strncmp(ce->name, info->traverse_path, info->pathlen);
 721         if (cmp)
 722                 return cmp;
 723
 724         pathlen = info->pathlen;
 725         ce_len = ce_namelen(ce);
 726
 727         if (ce_len < pathlen)
 728                 return -1;
 729
 730         ce_len -= pathlen;
 731         ce_name = ce->name + pathlen;
 732
 733         len = tree_entry_len(n);
 734         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 735 }
 736
 737 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 738 {
 739         int cmp = do_compare_entry(ce, info, n);
 740         if (cmp)
 741                 return cmp;
 742
 743         /*
 744          * Even if the beginning compared identically, the ce should
 745          * compare as bigger than a directory leading up to it!
 746          */
 747         return ce_namelen(ce) > traverse_path_len(info, n);
 748 }
 749
 750 static int ce_in_traverse_path(const struct cache_entry *ce,
 751                                const struct traverse_info *info)
 752 {
 753         if (!info->prev)
 754                 return 1;
 755         if (do_compare_entry(ce, info->prev, &info->name))
 756                 return 0;
 757         /*
 758          * If ce (blob) is the same name as the path (which is a tree
 759          * we will be descending into), it won't be inside it.
 760          */
 761         return (info->pathlen < ce_namelen(ce));
 762 }
 763
 764 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
 765 {
 766         int len = traverse_path_len(info, n);
 767         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
 768
 769         ce->ce_mode = create_ce_mode(n->mode);
 770         ce->ce_flags = create_ce_flags(stage);
 771         ce->ce_namelen = len;
 772         oidcpy(&ce->oid, n->oid);
 773         make_traverse_path(ce->name, info, n);
 774
 775         return ce;
 776 }
 777
 778 static int unpack_nondirectories(int n, unsigned long mask,
 779                                  unsigned long dirmask,
 780                                  struct cache_entry **src,
 781                                  const struct name_entry *names,
 782                                  const struct traverse_info *info)
 783 {
 784         int i;
 785         struct unpack_trees_options *o = info->data;
 786         unsigned long conflicts = info->df_conflicts | dirmask;
 787
 788         /* Do we have *only* directories? Nothing to do */
 789         if (mask == dirmask && !src[0])
 790                 return 0;
 791
 792         /*
 793          * Ok, we've filled in up to any potential index entry in src[0],
 794          * now do the rest.
 795          */
 796         for (i = 0; i < n; i++) {
 797                 int stage;
 798                 unsigned int bit = 1ul << i;
 799                 if (conflicts & bit) {
 800                         src[i + o->merge] = o->df_conflict_entry;
 801                         continue;
 802                 }
 803                 if (!(mask & bit))
 804                         continue;
 805                 if (!o->merge)
 806                         stage = 0;
 807                 else if (i + 1 < o->head_idx)
 808                         stage = 1;
 809                 else if (i + 1 > o->head_idx)
 810                         stage = 3;
 811                 else
 812                         stage = 2;
 813                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
 814         }
 815
 816         if (o->merge) {
 817                 int rc = call_unpack_fn((const struct cache_entry * const *)src,
 818                                         o);
 819                 for (i = 0; i < n; i++) {
 820                         struct cache_entry *ce = src[i + o->merge];
 821                         if (ce != o->df_conflict_entry)
 822                                 free(ce);
 823                 }
 824                 return rc;
 825         }
 826
 827         for (i = 0; i < n; i++)
 828                 if (src[i] && src[i] != o->df_conflict_entry)
 829                         if (do_add_entry(o, src[i], 0, 0))
 830                                 return -1;
 831
 832         return 0;
 833 }
 834
 835 static int unpack_failed(struct unpack_trees_options *o, const char *message)
 836 {
 837         discard_index(&o->result);
 838         if (!o->gently && !o->exiting_early) {
 839                 if (message)
 840                         return error("%s", message);
 841                 return -1;
 842         }
 843         return -1;
 844 }
 845
 846 /*
 847  * The tree traversal is looking at name p.  If we have a matching entry,
 848  * return it.  If name p is a directory in the index, do not return
 849  * anything, as we will want to match it when the traversal descends into
 850  * the directory.
 851  */
 852 static int find_cache_pos(struct traverse_info *info,
 853                           const struct name_entry *p)
 854 {
 855         int pos;
 856         struct unpack_trees_options *o = info->data;
 857         struct index_state *index = o->src_index;
 858         int pfxlen = info->pathlen;
 859         int p_len = tree_entry_len(p);
 860
 861         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
 862                 const struct cache_entry *ce = index->cache[pos];
 863                 const char *ce_name, *ce_slash;
 864                 int cmp, ce_len;
 865
 866                 if (ce->ce_flags & CE_UNPACKED) {
 867                         /*
 868                          * cache_bottom entry is already unpacked, so
 869                          * we can never match it; don't check it
 870                          * again.
 871                          */
 872                         if (pos == o->cache_bottom)
 873                                 ++o->cache_bottom;
 874                         continue;
 875                 }
 876                 if (!ce_in_traverse_path(ce, info)) {
 877                         /*
 878                          * Check if we can skip future cache checks
 879                          * (because we're already past all possible
 880                          * entries in the traverse path).
 881                          */
 882                         if (info->traverse_path) {
 883                                 if (strncmp(ce->name, info->traverse_path,
 884                                             info->pathlen) > 0)
 885                                         break;
 886                         }
 887                         continue;
 888                 }
 889                 ce_name = ce->name + pfxlen;
 890                 ce_slash = strchr(ce_name, '/');
 891                 if (ce_slash)
 892                         ce_len = ce_slash - ce_name;
 893                 else
 894                         ce_len = ce_namelen(ce) - pfxlen;
 895                 cmp = name_compare(p->path, p_len, ce_name, ce_len);
 896                 /*
 897                  * Exact match; if we have a directory we need to
 898                  * delay returning it.
 899                  */
 900                 if (!cmp)
 901                         return ce_slash ? -2 - pos : pos;
 902                 if (0 < cmp)
 903                         continue; /* keep looking */
 904                 /*
 905                  * ce_name sorts after p->path; could it be that we
 906                  * have files under p->path directory in the index?
 907                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
 908                  * have "t/a" in the index.
 909                  */
 910                 if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
 911                     ce_name[p_len] < '/')
 912                         continue; /* keep looking */
 913                 break;
 914         }
 915         return -1;
 916 }
 917
 918 static struct cache_entry *find_cache_entry(struct traverse_info *info,
 919                                             const struct name_entry *p)
 920 {
 921         int pos = find_cache_pos(info, p);
 922         struct unpack_trees_options *o = info->data;
 923
 924         if (0 <= pos)
 925                 return o->src_index->cache[pos];
 926         else
 927                 return NULL;
 928 }
 929
 930 static void debug_path(struct traverse_info *info)
 931 {
 932         if (info->prev) {
 933                 debug_path(info->prev);
 934                 if (*info->prev->name.path)
 935                         putchar('/');
 936         }
 937         printf("%s", info->name.path);
 938 }
 939
 940 static void debug_name_entry(int i, struct name_entry *n)
 941 {
 942         printf("ent#%d %06o %s\n", i,
 943                n->path ? n->mode : 0,
 944                n->path ? n->path : "(missing)");
 945 }
 946
 947 static void debug_unpack_callback(int n,
 948                                   unsigned long mask,
 949                                   unsigned long dirmask,
 950                                   struct name_entry *names,
 951                                   struct traverse_info *info)
 952 {
 953         int i;
 954         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
 955                mask, dirmask, n);
 956         debug_path(info);
 957         putchar('\n');
 958         for (i = 0; i < n; i++)
 959                 debug_name_entry(i, names + i);
 960 }
 961
 962 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
 963 {
 964         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 965         struct unpack_trees_options *o = info->data;
 966         const struct name_entry *p = names;
 967
 968         /* Find first entry with a real name (we could use "mask" too) */
 969         while (!p->mode)
 970                 p++;
 971
 972         if (o->debug_unpack)
 973                 debug_unpack_callback(n, mask, dirmask, names, info);
 974
 975         /* Are we supposed to look at the index too? */
 976         if (o->merge) {
 977                 while (1) {
 978                         int cmp;
 979                         struct cache_entry *ce;
 980
 981                         if (o->diff_index_cached)
 982                                 ce = next_cache_entry(o);
 983                         else
 984                                 ce = find_cache_entry(info, p);
 985
 986                         if (!ce)
 987                                 break;
 988                         cmp = compare_entry(ce, info, p);
 989                         if (cmp < 0) {
 990                                 if (unpack_index_entry(ce, o) < 0)
 991                                         return unpack_failed(o, NULL);
 992                                 continue;
 993                         }
 994                         if (!cmp) {
 995                                 if (ce_stage(ce)) {
 996                                         /*
 997                                          * If we skip unmerged index
 998                                          * entries, we'll skip this
 999                                          * entry *and* the tree
1000                                          * entries associated with it!
1001                                          */
1002                                         if (o->skip_unmerged) {
1003                                                 add_same_unmerged(ce, o);
1004                                                 return mask;
1005                                         }
1006                                 }
1007                                 src[0] = ce;
1008                         }
1009                         break;
1010                 }
1011         }
1012
1013         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
1014                 return -1;
1015
1016         if (o->merge && src[0]) {
1017                 if (ce_stage(src[0]))
1018                         mark_ce_used_same_name(src[0], o);
1019                 else
1020                         mark_ce_used(src[0], o);
1021         }
1022
1023         /* Now handle any directories.. */
1024         if (dirmask) {
1025                 /* special case: "diff-index --cached" looking at a tree */
1026                 if (o->diff_index_cached &&
1027                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
1028                         int matches;
1029                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
1030                                                                names, info);
1031                         /*
1032                          * Everything under the name matches; skip the
1033                          * entire hierarchy.  diff_index_cached codepath
1034                          * special cases D/F conflicts in such a way that
1035                          * it does not do any look-ahead, so this is safe.
1036                          */
1037                         if (matches) {
1038                                 o->cache_bottom += matches;
1039                                 return mask;
1040                         }
1041                 }
1042
1043                 if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
1044                                              names, info) < 0)
1045                         return -1;
1046                 return mask;
1047         }
1048
1049         return mask;
1050 }
1051
1052 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
1053                             struct strbuf *prefix,
1054                             int select_mask, int clear_mask,
1055                             struct exclude_list *el, int defval);
1056
1057 /* Whole directory matching */
1058 static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
1059                               struct strbuf *prefix,
1060                               char *basename,
1061                               int select_mask, int clear_mask,
1062                               struct exclude_list *el, int defval)
1063 {
1064         struct cache_entry **cache_end;
1065         int dtype = DT_DIR;
1066         int ret = is_excluded_from_list(prefix->buf, prefix->len,
1067                                         basename, &dtype, el, &the_index);
1068         int rc;
1069
1070         strbuf_addch(prefix, '/');
1071
1072         /* If undecided, use matching result of parent dir in defval */
1073         if (ret < 0)
1074                 ret = defval;
1075
1076         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
1077                 struct cache_entry *ce = *cache_end;
1078                 if (strncmp(ce->name, prefix->buf, prefix->len))
1079                         break;
1080         }
1081
1082         /*
1083          * TODO: check el, if there are no patterns that may conflict
1084          * with ret (iow, we know in advance the incl/excl
1085          * decision for the entire directory), clear flag here without
1086          * calling clear_ce_flags_1(). That function will call
1087          * the expensive is_excluded_from_list() on every entry.
1088          */
1089         rc = clear_ce_flags_1(cache, cache_end - cache,
1090                               prefix,
1091                               select_mask, clear_mask,
1092                               el, ret);
1093         strbuf_setlen(prefix, prefix->len - 1);
1094         return rc;
1095 }
1096
1097 /*
1098  * Traverse the index, find every entry that matches according to
1099  * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
1100  * number of traversed entries.
1101  *
1102  * If select_mask is non-zero, only entries whose ce_flags has on of
1103  * those bits enabled are traversed.
1104  *
1105  * cache        : pointer to an index entry
1106  * prefix_len   : an offset to its path
1107  *
1108  * The current path ("prefix") including the trailing '/' is
1109  *   cache[0]->name[0..(prefix_len-1)]
1110  * Top level path has prefix_len zero.
1111  */
1112 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
1113                             struct strbuf *prefix,
1114                             int select_mask, int clear_mask,
1115                             struct exclude_list *el, int defval)
1116 {
1117         struct cache_entry **cache_end = cache + nr;
1118
1119         /*
1120          * Process all entries that have the given prefix and meet
1121          * select_mask condition
1122          */
1123         while(cache != cache_end) {
1124                 struct cache_entry *ce = *cache;
1125                 const char *name, *slash;
1126                 int len, dtype, ret;
1127
1128                 if (select_mask && !(ce->ce_flags & select_mask)) {
1129                         cache++;
1130                         continue;
1131                 }
1132
1133                 if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
1134                         break;
1135
1136                 name = ce->name + prefix->len;
1137                 slash = strchr(name, '/');
1138
1139                 /* If it's a directory, try whole directory match first */
1140                 if (slash) {
1141                         int processed;
1142
1143                         len = slash - name;
1144                         strbuf_add(prefix, name, len);
1145
1146                         processed = clear_ce_flags_dir(cache, cache_end - cache,
1147                                                        prefix,
1148                                                        prefix->buf + prefix->len - len,
1149                                                        select_mask, clear_mask,
1150                                                        el, defval);
1151
1152                         /* clear_c_f_dir eats a whole dir already? */
1153                         if (processed) {
1154                                 cache += processed;
1155                                 strbuf_setlen(prefix, prefix->len - len);
1156                                 continue;
1157                         }
1158
1159                         strbuf_addch(prefix, '/');
1160                         cache += clear_ce_flags_1(cache, cache_end - cache,
1161                                                   prefix,
1162                                                   select_mask, clear_mask, el, defval);
1163                         strbuf_setlen(prefix, prefix->len - len - 1);
1164                         continue;
1165                 }
1166
1167                 /* Non-directory */
1168                 dtype = ce_to_dtype(ce);
1169                 ret = is_excluded_from_list(ce->name, ce_namelen(ce),
1170                                             name, &dtype, el, &the_index);
1171                 if (ret < 0)
1172                         ret = defval;
1173                 if (ret > 0)
1174                         ce->ce_flags &= ~clear_mask;
1175                 cache++;
1176         }
1177         return nr - (cache_end - cache);
1178 }
1179
1180 static int clear_ce_flags(struct cache_entry **cache, int nr,
1181                             int select_mask, int clear_mask,
1182                             struct exclude_list *el)
1183 {
1184         static struct strbuf prefix = STRBUF_INIT;
1185
1186         strbuf_reset(&prefix);
1187
1188         return clear_ce_flags_1(cache, nr,
1189                                 &prefix,
1190                                 select_mask, clear_mask,
1191                                 el, 0);
1192 }
1193
1194 /*
1195  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
1196  */
1197 static void mark_new_skip_worktree(struct exclude_list *el,
1198                                    struct index_state *the_index,
1199                                    int select_flag, int skip_wt_flag)
1200 {
1201         int i;
1202
1203         /*
1204          * 1. Pretend the narrowest worktree: only unmerged entries
1205          * are checked out
1206          */
1207         for (i = 0; i < the_index->cache_nr; i++) {
1208                 struct cache_entry *ce = the_index->cache[i];
1209
1210                 if (select_flag && !(ce->ce_flags & select_flag))
1211                         continue;
1212
1213                 if (!ce_stage(ce))
1214                         ce->ce_flags |= skip_wt_flag;
1215                 else
1216                         ce->ce_flags &= ~skip_wt_flag;
1217         }
1218
1219         /*
1220          * 2. Widen worktree according to sparse-checkout file.
1221          * Matched entries will have skip_wt_flag cleared (i.e. "in")
1222          */
1223         clear_ce_flags(the_index->cache, the_index->cache_nr,
1224                        select_flag, skip_wt_flag, el);
1225 }
1226
1227 static int verify_absent(const struct cache_entry *,
1228                          enum unpack_trees_error_types,
1229                          struct unpack_trees_options *);
1230 /*
1231  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1232  * resulting index, -2 on failure to reflect the changes to the work tree.
1233  *
1234  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1235  */
1236 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1237 {
1238         int i, ret;
1239         static struct cache_entry *dfc;
1240         struct exclude_list el;
1241
1242         if (len > MAX_UNPACK_TREES)
1243                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1244
1245         memset(&el, 0, sizeof(el));
1246         if (!core_apply_sparse_checkout || !o->update)
1247                 o->skip_sparse_checkout = 1;
1248         if (!o->skip_sparse_checkout) {
1249                 char *sparse = git_pathdup("info/sparse-checkout");
1250                 if (add_excludes_from_file_to_list(sparse, "", 0, &el, NULL) < 0)
1251                         o->skip_sparse_checkout = 1;
1252                 else
1253                         o->el = &el;
1254                 free(sparse);
1255         }
1256
1257         memset(&o->result, 0, sizeof(o->result));
1258         o->result.initialized = 1;
1259         o->result.timestamp.sec = o->src_index->timestamp.sec;
1260         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1261         o->result.version = o->src_index->version;
1262         o->result.split_index = o->src_index->split_index;
1263         if (o->result.split_index)
1264                 o->result.split_index->refcount++;
1265         hashcpy(o->result.sha1, o->src_index->sha1);
1266         o->merge_size = len;
1267         mark_all_ce_unused(o->src_index);
1268
1269         /*
1270          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1271          */
1272         if (!o->skip_sparse_checkout)
1273                 mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1274
1275         if (!dfc)
1276                 dfc = xcalloc(1, cache_entry_size(0));
1277         o->df_conflict_entry = dfc;
1278
1279         if (len) {
1280                 const char *prefix = o->prefix ? o->prefix : "";
1281                 struct traverse_info info;
1282
1283                 setup_traverse_info(&info, prefix);
1284                 info.fn = unpack_callback;
1285                 info.data = o;
1286                 info.show_all_errors = o->show_all_errors;
1287                 info.pathspec = o->pathspec;
1288
1289                 if (o->prefix) {
1290                         /*
1291                          * Unpack existing index entries that sort before the
1292                          * prefix the tree is spliced into.  Note that o->merge
1293                          * is always true in this case.
1294                          */
1295                         while (1) {
1296                                 struct cache_entry *ce = next_cache_entry(o);
1297                                 if (!ce)
1298                                         break;
1299                                 if (ce_in_traverse_path(ce, &info))
1300                                         break;
1301                                 if (unpack_index_entry(ce, o) < 0)
1302                                         goto return_failed;
1303                         }
1304                 }
1305
1306                 if (traverse_trees(len, t, &info) < 0)
1307                         goto return_failed;
1308         }
1309
1310         /* Any left-over entries in the index? */
1311         if (o->merge) {
1312                 while (1) {
1313                         struct cache_entry *ce = next_cache_entry(o);
1314                         if (!ce)
1315                                 break;
1316                         if (unpack_index_entry(ce, o) < 0)
1317                                 goto return_failed;
1318                 }
1319         }
1320         mark_all_ce_unused(o->src_index);
1321
1322         if (o->trivial_merges_only && o->nontrivial_merge) {
1323                 ret = unpack_failed(o, "Merge requires file-level merging");
1324                 goto done;
1325         }
1326
1327         if (!o->skip_sparse_checkout) {
1328                 int empty_worktree = 1;
1329
1330                 /*
1331                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1332                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1333                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1334                  */
1335                 mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1336
1337                 ret = 0;
1338                 for (i = 0; i < o->result.cache_nr; i++) {
1339                         struct cache_entry *ce = o->result.cache[i];
1340
1341                         /*
1342                          * Entries marked with CE_ADDED in merged_entry() do not have
1343                          * verify_absent() check (the check is effectively disabled
1344                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1345                          *
1346                          * Do the real check now because we have had
1347                          * correct CE_NEW_SKIP_WORKTREE
1348                          */
1349                         if (ce->ce_flags & CE_ADDED &&
1350                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1351                                 if (!o->show_all_errors)
1352                                         goto return_failed;
1353                                 ret = -1;
1354                         }
1355
1356                         if (apply_sparse_checkout(&o->result, ce, o)) {
1357                                 if (!o->show_all_errors)
1358                                         goto return_failed;
1359                                 ret = -1;
1360                         }
1361                         if (!ce_skip_worktree(ce))
1362                                 empty_worktree = 0;
1363
1364                 }
1365                 if (ret < 0)
1366                         goto return_failed;
1367                 /*
1368                  * Sparse checkout is meant to narrow down checkout area
1369                  * but it does not make sense to narrow down to empty working
1370                  * tree. This is usually a mistake in sparse checkout rules.
1371                  * Do not allow users to do that.
1372                  */
1373                 if (o->result.cache_nr && empty_worktree) {
1374                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1375                         goto done;
1376                 }
1377         }
1378
1379         o->src_index = NULL;
1380         ret = check_updates(o) ? (-2) : 0;
1381         if (o->dst_index) {
1382                 if (!ret) {
1383                         if (!o->result.cache_tree)
1384                                 o->result.cache_tree = cache_tree();
1385                         if (!cache_tree_fully_valid(o->result.cache_tree))
1386                                 cache_tree_update(&o->result,
1387                                                   WRITE_TREE_SILENT |
1388                                                   WRITE_TREE_REPAIR);
1389                 }
1390                 move_index_extensions(&o->result, o->dst_index);
1391                 discard_index(o->dst_index);
1392                 *o->dst_index = o->result;
1393         } else {
1394                 discard_index(&o->result);
1395         }
1396
1397 done:
1398         clear_exclude_list(&el);
1399         return ret;
1400
1401 return_failed:
1402         if (o->show_all_errors)
1403                 display_error_msgs(o);
1404         mark_all_ce_unused(o->src_index);
1405         ret = unpack_failed(o, NULL);
1406         if (o->exiting_early)
1407                 ret = 0;
1408         goto done;
1409 }
1410
1411 /* Here come the merge functions */
1412
1413 static int reject_merge(const struct cache_entry *ce,
1414                         struct unpack_trees_options *o)
1415 {
1416         return o->gently ? -1 :
1417                 add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1418 }
1419
1420 static int same(const struct cache_entry *a, const struct cache_entry *b)
1421 {
1422         if (!!a != !!b)
1423                 return 0;
1424         if (!a && !b)
1425                 return 1;
1426         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1427                 return 0;
1428         return a->ce_mode == b->ce_mode &&
1429                !oidcmp(&a->oid, &b->oid);
1430 }
1431
1432
1433 /*
1434  * When a CE gets turned into an unmerged entry, we
1435  * want it to be up-to-date
1436  */
1437 static int verify_uptodate_1(const struct cache_entry *ce,
1438                              struct unpack_trees_options *o,
1439                              enum unpack_trees_error_types error_type)
1440 {
1441         struct stat st;
1442
1443         if (o->index_only)
1444                 return 0;
1445
1446         /*
1447          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1448          * if this entry is truly up-to-date because this file may be
1449          * overwritten.
1450          */
1451         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1452                 ; /* keep checking */
1453         else if (o->reset || ce_uptodate(ce))
1454                 return 0;
1455
1456         if (!lstat(ce->name, &st)) {
1457                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1458                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1459
1460                 if (submodule_from_ce(ce)) {
1461                         int r = check_submodule_move_head(ce,
1462                                 "HEAD", oid_to_hex(&ce->oid), o);
1463                         if (r)
1464                                 return o->gently ? -1 :
1465                                         add_rejected_path(o, error_type, ce->name);
1466                         return 0;
1467                 }
1468
1469                 if (!changed)
1470                         return 0;
1471                 /*
1472                  * Historic default policy was to allow submodule to be out
1473                  * of sync wrt the superproject index. If the submodule was
1474                  * not considered interesting above, we don't care here.
1475                  */
1476                 if (S_ISGITLINK(ce->ce_mode))
1477                         return 0;
1478
1479                 errno = 0;
1480         }
1481         if (errno == ENOENT)
1482                 return 0;
1483         return o->gently ? -1 :
1484                 add_rejected_path(o, error_type, ce->name);
1485 }
1486
1487 static int verify_uptodate(const struct cache_entry *ce,
1488                            struct unpack_trees_options *o)
1489 {
1490         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1491                 return 0;
1492         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1493 }
1494
1495 static int verify_uptodate_sparse(const struct cache_entry *ce,
1496                                   struct unpack_trees_options *o)
1497 {
1498         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1499 }
1500
1501 static void invalidate_ce_path(const struct cache_entry *ce,
1502                                struct unpack_trees_options *o)
1503 {
1504         if (!ce)
1505                 return;
1506         cache_tree_invalidate_path(o->src_index, ce->name);
1507         untracked_cache_invalidate_path(o->src_index, ce->name);
1508 }
1509
1510 /*
1511  * Check that checking out ce->sha1 in subdir ce->name is not
1512  * going to overwrite any working files.
1513  *
1514  * Currently, git does not checkout subprojects during a superproject
1515  * checkout, so it is not going to overwrite anything.
1516  */
1517 static int verify_clean_submodule(const char *old_sha1,
1518                                   const struct cache_entry *ce,
1519                                   enum unpack_trees_error_types error_type,
1520                                   struct unpack_trees_options *o)
1521 {
1522         if (!submodule_from_ce(ce))
1523                 return 0;
1524
1525         return check_submodule_move_head(ce, old_sha1,
1526                                          oid_to_hex(&ce->oid), o);
1527 }
1528
1529 static int verify_clean_subdirectory(const struct cache_entry *ce,
1530                                      enum unpack_trees_error_types error_type,
1531                                      struct unpack_trees_options *o)
1532 {
1533         /*
1534          * we are about to extract "ce->name"; we would not want to lose
1535          * anything in the existing directory there.
1536          */
1537         int namelen;
1538         int i;
1539         struct dir_struct d;
1540         char *pathbuf;
1541         int cnt = 0;
1542
1543         if (S_ISGITLINK(ce->ce_mode)) {
1544                 unsigned char sha1[20];
1545                 int sub_head = resolve_gitlink_ref(ce->name, "HEAD", sha1);
1546                 /*
1547                  * If we are not going to update the submodule, then
1548                  * we don't care.
1549                  */
1550                 if (!sub_head && !hashcmp(sha1, ce->oid.hash))
1551                         return 0;
1552                 return verify_clean_submodule(sub_head ? NULL : sha1_to_hex(sha1),
1553                                               ce, error_type, o);
1554         }
1555
1556         /*
1557          * First let's make sure we do not have a local modification
1558          * in that directory.
1559          */
1560         namelen = ce_namelen(ce);
1561         for (i = locate_in_src_index(ce, o);
1562              i < o->src_index->cache_nr;
1563              i++) {
1564                 struct cache_entry *ce2 = o->src_index->cache[i];
1565                 int len = ce_namelen(ce2);
1566                 if (len < namelen ||
1567                     strncmp(ce->name, ce2->name, namelen) ||
1568                     ce2->name[namelen] != '/')
1569                         break;
1570                 /*
1571                  * ce2->name is an entry in the subdirectory to be
1572                  * removed.
1573                  */
1574                 if (!ce_stage(ce2)) {
1575                         if (verify_uptodate(ce2, o))
1576                                 return -1;
1577                         add_entry(o, ce2, CE_REMOVE, 0);
1578                         mark_ce_used(ce2, o);
1579                 }
1580                 cnt++;
1581         }
1582
1583         /*
1584          * Then we need to make sure that we do not lose a locally
1585          * present file that is not ignored.
1586          */
1587         pathbuf = xstrfmt("%.*s/", namelen, ce->name);
1588
1589         memset(&d, 0, sizeof(d));
1590         if (o->dir)
1591                 d.exclude_per_dir = o->dir->exclude_per_dir;
1592         i = read_directory(&d, &the_index, pathbuf, namelen+1, NULL);
1593         if (i)
1594                 return o->gently ? -1 :
1595                         add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1596         free(pathbuf);
1597         return cnt;
1598 }
1599
1600 /*
1601  * This gets called when there was no index entry for the tree entry 'dst',
1602  * but we found a file in the working tree that 'lstat()' said was fine,
1603  * and we're on a case-insensitive filesystem.
1604  *
1605  * See if we can find a case-insensitive match in the index that also
1606  * matches the stat information, and assume it's that other file!
1607  */
1608 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1609 {
1610         const struct cache_entry *src;
1611
1612         src = index_file_exists(o->src_index, name, len, 1);
1613         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1614 }
1615
1616 static int check_ok_to_remove(const char *name, int len, int dtype,
1617                               const struct cache_entry *ce, struct stat *st,
1618                               enum unpack_trees_error_types error_type,
1619                               struct unpack_trees_options *o)
1620 {
1621         const struct cache_entry *result;
1622
1623         /*
1624          * It may be that the 'lstat()' succeeded even though
1625          * target 'ce' was absent, because there is an old
1626          * entry that is different only in case..
1627          *
1628          * Ignore that lstat() if it matches.
1629          */
1630         if (ignore_case && icase_exists(o, name, len, st))
1631                 return 0;
1632
1633         if (o->dir &&
1634             is_excluded(o->dir, &the_index, name, &dtype))
1635                 /*
1636                  * ce->name is explicitly excluded, so it is Ok to
1637                  * overwrite it.
1638                  */
1639                 return 0;
1640         if (S_ISDIR(st->st_mode)) {
1641                 /*
1642                  * We are checking out path "foo" and
1643                  * found "foo/." in the working tree.
1644                  * This is tricky -- if we have modified
1645                  * files that are in "foo/" we would lose
1646                  * them.
1647                  */
1648                 if (verify_clean_subdirectory(ce, error_type, o) < 0)
1649                         return -1;
1650                 return 0;
1651         }
1652
1653         /*
1654          * The previous round may already have decided to
1655          * delete this path, which is in a subdirectory that
1656          * is being replaced with a blob.
1657          */
1658         result = index_file_exists(&o->result, name, len, 0);
1659         if (result) {
1660                 if (result->ce_flags & CE_REMOVE)
1661                         return 0;
1662         }
1663
1664         return o->gently ? -1 :
1665                 add_rejected_path(o, error_type, name);
1666 }
1667
1668 /*
1669  * We do not want to remove or overwrite a working tree file that
1670  * is not tracked, unless it is ignored.
1671  */
1672 static int verify_absent_1(const struct cache_entry *ce,
1673                            enum unpack_trees_error_types error_type,
1674                            struct unpack_trees_options *o)
1675 {
1676         int len;
1677         struct stat st;
1678
1679         if (o->index_only || o->reset || !o->update)
1680                 return 0;
1681
1682         len = check_leading_path(ce->name, ce_namelen(ce));
1683         if (!len)
1684                 return 0;
1685         else if (len > 0) {
1686                 char *path;
1687                 int ret;
1688
1689                 path = xmemdupz(ce->name, len);
1690                 if (lstat(path, &st))
1691                         ret = error_errno("cannot stat '%s'", path);
1692                 else {
1693                         if (submodule_from_ce(ce))
1694                                 ret = check_submodule_move_head(ce,
1695                                                                 oid_to_hex(&ce->oid),
1696                                                                 NULL, o);
1697                         else
1698                                 ret = check_ok_to_remove(path, len, DT_UNKNOWN, NULL,
1699                                                          &st, error_type, o);
1700                 }
1701                 free(path);
1702                 return ret;
1703         } else if (lstat(ce->name, &st)) {
1704                 if (errno != ENOENT)
1705                         return error_errno("cannot stat '%s'", ce->name);
1706                 return 0;
1707         } else {
1708                 if (submodule_from_ce(ce))
1709                         return check_submodule_move_head(ce, oid_to_hex(&ce->oid),
1710                                                          NULL, o);
1711
1712                 return check_ok_to_remove(ce->name, ce_namelen(ce),
1713                                           ce_to_dtype(ce), ce, &st,
1714                                           error_type, o);
1715         }
1716 }
1717
1718 static int verify_absent(const struct cache_entry *ce,
1719                          enum unpack_trees_error_types error_type,
1720                          struct unpack_trees_options *o)
1721 {
1722         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1723                 return 0;
1724         return verify_absent_1(ce, error_type, o);
1725 }
1726
1727 static int verify_absent_sparse(const struct cache_entry *ce,
1728                                 enum unpack_trees_error_types error_type,
1729                                 struct unpack_trees_options *o)
1730 {
1731         enum unpack_trees_error_types orphaned_error = error_type;
1732         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1733                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1734
1735         return verify_absent_1(ce, orphaned_error, o);
1736 }
1737
1738 static int merged_entry(const struct cache_entry *ce,
1739                         const struct cache_entry *old,
1740                         struct unpack_trees_options *o)
1741 {
1742         int update = CE_UPDATE;
1743         struct cache_entry *merge = dup_entry(ce);
1744
1745         if (!old) {
1746                 /*
1747                  * New index entries. In sparse checkout, the following
1748                  * verify_absent() will be delayed until after
1749                  * traverse_trees() finishes in unpack_trees(), then:
1750                  *
1751                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1752                  *  - verify_absent() be called again, this time with
1753                  *    correct CE_NEW_SKIP_WORKTREE
1754                  *
1755                  * verify_absent() call here does nothing in sparse
1756                  * checkout (i.e. o->skip_sparse_checkout == 0)
1757                  */
1758                 update |= CE_ADDED;
1759                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1760
1761                 if (verify_absent(merge,
1762                                   ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1763                         free(merge);
1764                         return -1;
1765                 }
1766                 invalidate_ce_path(merge, o);
1767
1768                 if (submodule_from_ce(ce)) {
1769                         int ret = check_submodule_move_head(ce, NULL,
1770                                                             oid_to_hex(&ce->oid),
1771                                                             o);
1772                         if (ret)
1773                                 return ret;
1774                 }
1775
1776         } else if (!(old->ce_flags & CE_CONFLICTED)) {
1777                 /*
1778                  * See if we can re-use the old CE directly?
1779                  * That way we get the uptodate stat info.
1780                  *
1781                  * This also removes the UPDATE flag on a match; otherwise
1782                  * we will end up overwriting local changes in the work tree.
1783                  */
1784                 if (same(old, merge)) {
1785                         copy_cache_entry(merge, old);
1786                         update = 0;
1787                 } else {
1788                         if (verify_uptodate(old, o)) {
1789                                 free(merge);
1790                                 return -1;
1791                         }
1792                         /* Migrate old flags over */
1793                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1794                         invalidate_ce_path(old, o);
1795                 }
1796
1797                 if (submodule_from_ce(ce)) {
1798                         int ret = check_submodule_move_head(ce, oid_to_hex(&old->oid),
1799                                                             oid_to_hex(&ce->oid),
1800                                                             o);
1801                         if (ret)
1802                                 return ret;
1803                 }
1804         } else {
1805                 /*
1806                  * Previously unmerged entry left as an existence
1807                  * marker by read_index_unmerged();
1808                  */
1809                 invalidate_ce_path(old, o);
1810         }
1811
1812         do_add_entry(o, merge, update, CE_STAGEMASK);
1813         return 1;
1814 }
1815
1816 static int deleted_entry(const struct cache_entry *ce,
1817                          const struct cache_entry *old,
1818                          struct unpack_trees_options *o)
1819 {
1820         /* Did it exist in the index? */
1821         if (!old) {
1822                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1823                         return -1;
1824                 return 0;
1825         }
1826         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1827                 return -1;
1828         add_entry(o, ce, CE_REMOVE, 0);
1829         invalidate_ce_path(ce, o);
1830         return 1;
1831 }
1832
1833 static int keep_entry(const struct cache_entry *ce,
1834                       struct unpack_trees_options *o)
1835 {
1836         add_entry(o, ce, 0, 0);
1837         return 1;
1838 }
1839
1840 #if DBRT_DEBUG
1841 static void show_stage_entry(FILE *o,
1842                              const char *label, const struct cache_entry *ce)
1843 {
1844         if (!ce)
1845                 fprintf(o, "%s (missing)\n", label);
1846         else
1847                 fprintf(o, "%s%06o %s %d\t%s\n",
1848                         label,
1849                         ce->ce_mode,
1850                         oid_to_hex(&ce->oid),
1851                         ce_stage(ce),
1852                         ce->name);
1853 }
1854 #endif
1855
1856 int threeway_merge(const struct cache_entry * const *stages,
1857                    struct unpack_trees_options *o)
1858 {
1859         const struct cache_entry *index;
1860         const struct cache_entry *head;
1861         const struct cache_entry *remote = stages[o->head_idx + 1];
1862         int count;
1863         int head_match = 0;
1864         int remote_match = 0;
1865
1866         int df_conflict_head = 0;
1867         int df_conflict_remote = 0;
1868
1869         int any_anc_missing = 0;
1870         int no_anc_exists = 1;
1871         int i;
1872
1873         for (i = 1; i < o->head_idx; i++) {
1874                 if (!stages[i] || stages[i] == o->df_conflict_entry)
1875                         any_anc_missing = 1;
1876                 else
1877                         no_anc_exists = 0;
1878         }
1879
1880         index = stages[0];
1881         head = stages[o->head_idx];
1882
1883         if (head == o->df_conflict_entry) {
1884                 df_conflict_head = 1;
1885                 head = NULL;
1886         }
1887
1888         if (remote == o->df_conflict_entry) {
1889                 df_conflict_remote = 1;
1890                 remote = NULL;
1891         }
1892
1893         /*
1894          * First, if there's a #16 situation, note that to prevent #13
1895          * and #14.
1896          */
1897         if (!same(remote, head)) {
1898                 for (i = 1; i < o->head_idx; i++) {
1899                         if (same(stages[i], head)) {
1900                                 head_match = i;
1901                         }
1902                         if (same(stages[i], remote)) {
1903                                 remote_match = i;
1904                         }
1905                 }
1906         }
1907
1908         /*
1909          * We start with cases where the index is allowed to match
1910          * something other than the head: #14(ALT) and #2ALT, where it
1911          * is permitted to match the result instead.
1912          */
1913         /* #14, #14ALT, #2ALT */
1914         if (remote && !df_conflict_head && head_match && !remote_match) {
1915                 if (index && !same(index, remote) && !same(index, head))
1916                         return reject_merge(index, o);
1917                 return merged_entry(remote, index, o);
1918         }
1919         /*
1920          * If we have an entry in the index cache, then we want to
1921          * make sure that it matches head.
1922          */
1923         if (index && !same(index, head))
1924                 return reject_merge(index, o);
1925
1926         if (head) {
1927                 /* #5ALT, #15 */
1928                 if (same(head, remote))
1929                         return merged_entry(head, index, o);
1930                 /* #13, #3ALT */
1931                 if (!df_conflict_remote && remote_match && !head_match)
1932                         return merged_entry(head, index, o);
1933         }
1934
1935         /* #1 */
1936         if (!head && !remote && any_anc_missing)
1937                 return 0;
1938
1939         /*
1940          * Under the "aggressive" rule, we resolve mostly trivial
1941          * cases that we historically had git-merge-one-file resolve.
1942          */
1943         if (o->aggressive) {
1944                 int head_deleted = !head;
1945                 int remote_deleted = !remote;
1946                 const struct cache_entry *ce = NULL;
1947
1948                 if (index)
1949                         ce = index;
1950                 else if (head)
1951                         ce = head;
1952                 else if (remote)
1953                         ce = remote;
1954                 else {
1955                         for (i = 1; i < o->head_idx; i++) {
1956                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
1957                                         ce = stages[i];
1958                                         break;
1959                                 }
1960                         }
1961                 }
1962
1963                 /*
1964                  * Deleted in both.
1965                  * Deleted in one and unchanged in the other.
1966                  */
1967                 if ((head_deleted && remote_deleted) ||
1968                     (head_deleted && remote && remote_match) ||
1969                     (remote_deleted && head && head_match)) {
1970                         if (index)
1971                                 return deleted_entry(index, index, o);
1972                         if (ce && !head_deleted) {
1973                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1974                                         return -1;
1975                         }
1976                         return 0;
1977                 }
1978                 /*
1979                  * Added in both, identically.
1980                  */
1981                 if (no_anc_exists && head && remote && same(head, remote))
1982                         return merged_entry(head, index, o);
1983
1984         }
1985
1986         /* Below are "no merge" cases, which require that the index be
1987          * up-to-date to avoid the files getting overwritten with
1988          * conflict resolution files.
1989          */
1990         if (index) {
1991                 if (verify_uptodate(index, o))
1992                         return -1;
1993         }
1994
1995         o->nontrivial_merge = 1;
1996
1997         /* #2, #3, #4, #6, #7, #9, #10, #11. */
1998         count = 0;
1999         if (!head_match || !remote_match) {
2000                 for (i = 1; i < o->head_idx; i++) {
2001                         if (stages[i] && stages[i] != o->df_conflict_entry) {
2002                                 keep_entry(stages[i], o);
2003                                 count++;
2004                                 break;
2005                         }
2006                 }
2007         }
2008 #if DBRT_DEBUG
2009         else {
2010                 fprintf(stderr, "read-tree: warning #16 detected\n");
2011                 show_stage_entry(stderr, "head   ", stages[head_match]);
2012                 show_stage_entry(stderr, "remote ", stages[remote_match]);
2013         }
2014 #endif
2015         if (head) { count += keep_entry(head, o); }
2016         if (remote) { count += keep_entry(remote, o); }
2017         return count;
2018 }
2019
2020 /*
2021  * Two-way merge.
2022  *
2023  * The rule is to "carry forward" what is in the index without losing
2024  * information across a "fast-forward", favoring a successful merge
2025  * over a merge failure when it makes sense.  For details of the
2026  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
2027  *
2028  */
2029 int twoway_merge(const struct cache_entry * const *src,
2030                  struct unpack_trees_options *o)
2031 {
2032         const struct cache_entry *current = src[0];
2033         const struct cache_entry *oldtree = src[1];
2034         const struct cache_entry *newtree = src[2];
2035
2036         if (o->merge_size != 2)
2037                 return error("Cannot do a twoway merge of %d trees",
2038                              o->merge_size);
2039
2040         if (oldtree == o->df_conflict_entry)
2041                 oldtree = NULL;
2042         if (newtree == o->df_conflict_entry)
2043                 newtree = NULL;
2044
2045         if (current) {
2046                 if (current->ce_flags & CE_CONFLICTED) {
2047                         if (same(oldtree, newtree) || o->reset) {
2048                                 if (!newtree)
2049                                         return deleted_entry(current, current, o);
2050                                 else
2051                                         return merged_entry(newtree, current, o);
2052                         }
2053                         return reject_merge(current, o);
2054                 } else if ((!oldtree && !newtree) || /* 4 and 5 */
2055                          (!oldtree && newtree &&
2056                           same(current, newtree)) || /* 6 and 7 */
2057                          (oldtree && newtree &&
2058                           same(oldtree, newtree)) || /* 14 and 15 */
2059                          (oldtree && newtree &&
2060                           !same(oldtree, newtree) && /* 18 and 19 */
2061                           same(current, newtree))) {
2062                         return keep_entry(current, o);
2063                 } else if (oldtree && !newtree && same(current, oldtree)) {
2064                         /* 10 or 11 */
2065                         return deleted_entry(oldtree, current, o);
2066                 } else if (oldtree && newtree &&
2067                          same(current, oldtree) && !same(current, newtree)) {
2068                         /* 20 or 21 */
2069                         return merged_entry(newtree, current, o);
2070                 } else
2071                         return reject_merge(current, o);
2072         }
2073         else if (newtree) {
2074                 if (oldtree && !o->initial_checkout) {
2075                         /*
2076                          * deletion of the path was staged;
2077                          */
2078                         if (same(oldtree, newtree))
2079                                 return 1;
2080                         return reject_merge(oldtree, o);
2081                 }
2082                 return merged_entry(newtree, current, o);
2083         }
2084         return deleted_entry(oldtree, current, o);
2085 }
2086
2087 /*
2088  * Bind merge.
2089  *
2090  * Keep the index entries at stage0, collapse stage1 but make sure
2091  * stage0 does not have anything there.
2092  */
2093 int bind_merge(const struct cache_entry * const *src,
2094                struct unpack_trees_options *o)
2095 {
2096         const struct cache_entry *old = src[0];
2097         const struct cache_entry *a = src[1];
2098
2099         if (o->merge_size != 1)
2100                 return error("Cannot do a bind merge of %d trees",
2101                              o->merge_size);
2102         if (a && old)
2103                 return o->gently ? -1 :
2104                         error(ERRORMSG(o, ERROR_BIND_OVERLAP),
2105                               super_prefixed(a->name),
2106                               super_prefixed(old->name));
2107         if (!a)
2108                 return keep_entry(old, o);
2109         else
2110                 return merged_entry(a, NULL, o);
2111 }
2112
2113 /*
2114  * One-way merge.
2115  *
2116  * The rule is:
2117  * - take the stat information from stage0, take the data from stage1
2118  */
2119 int oneway_merge(const struct cache_entry * const *src,
2120                  struct unpack_trees_options *o)
2121 {
2122         const struct cache_entry *old = src[0];
2123         const struct cache_entry *a = src[1];
2124
2125         if (o->merge_size != 1)
2126                 return error("Cannot do a oneway merge of %d trees",
2127                              o->merge_size);
2128
2129         if (!a || a == o->df_conflict_entry)
2130                 return deleted_entry(old, old, o);
2131
2132         if (old && same(old, a)) {
2133                 int update = 0;
2134                 if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
2135                         struct stat st;
2136                         if (lstat(old->name, &st) ||
2137                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
2138                                 update |= CE_UPDATE;
2139                 }
2140                 add_entry(o, old, update, 0);
2141                 return 0;
2142         }
2143         return merged_entry(a, old, o);
2144 }