unpack-trees.c

   1 #define NO_THE_INDEX_COMPATIBILITY_MACROS
   2 #include "cache.h"
   3 #include "argv-array.h"
   4 #include "repository.h"
   5 #include "config.h"
   6 #include "dir.h"
   7 #include "tree.h"
   8 #include "tree-walk.h"
   9 #include "cache-tree.h"
  10 #include "unpack-trees.h"
  11 #include "progress.h"
  12 #include "refs.h"
  13 #include "attr.h"
  14 #include "split-index.h"
  15 #include "dir.h"
  16 #include "submodule.h"
  17 #include "submodule-config.h"
  18 #include "fsmonitor.h"
  19 #include "object-store.h"
  20 #include "fetch-object.h"
  21
  22 /*
  23  * Error messages expected by scripts out of plumbing commands such as
  24  * read-tree.  Non-scripted Porcelain is not required to use these messages
  25  * and in fact are encouraged to reword them to better suit their particular
  26  * situation better.  See how "git checkout" and "git merge" replaces
  27  * them using setup_unpack_trees_porcelain(), for example.
  28  */
  29 static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
  30         /* ERROR_WOULD_OVERWRITE */
  31         "Entry '%s' would be overwritten by merge. Cannot merge.",
  32
  33         /* ERROR_NOT_UPTODATE_FILE */
  34         "Entry '%s' not uptodate. Cannot merge.",
  35
  36         /* ERROR_NOT_UPTODATE_DIR */
  37         "Updating '%s' would lose untracked files in it",
  38
  39         /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
  40         "Untracked working tree file '%s' would be overwritten by merge.",
  41
  42         /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
  43         "Untracked working tree file '%s' would be removed by merge.",
  44
  45         /* ERROR_BIND_OVERLAP */
  46         "Entry '%s' overlaps with '%s'.  Cannot bind.",
  47
  48         /* ERROR_SPARSE_NOT_UPTODATE_FILE */
  49         "Entry '%s' not uptodate. Cannot update sparse checkout.",
  50
  51         /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
  52         "Working tree file '%s' would be overwritten by sparse checkout update.",
  53
  54         /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
  55         "Working tree file '%s' would be removed by sparse checkout update.",
  56
  57         /* ERROR_WOULD_LOSE_SUBMODULE */
  58         "Submodule '%s' cannot checkout new HEAD.",
  59 };
  60
  61 #define ERRORMSG(o,type) \
  62         ( ((o) && (o)->msgs[(type)]) \
  63           ? ((o)->msgs[(type)])      \
  64           : (unpack_plumbing_errors[(type)]) )
  65
  66 static const char *super_prefixed(const char *path)
  67 {
  68         /*
  69          * It is necessary and sufficient to have two static buffers
  70          * here, as the return value of this function is fed to
  71          * error() using the unpack_*_errors[] templates we see above.
  72          */
  73         static struct strbuf buf[2] = {STRBUF_INIT, STRBUF_INIT};
  74         static int super_prefix_len = -1;
  75         static unsigned idx = ARRAY_SIZE(buf) - 1;
  76
  77         if (super_prefix_len < 0) {
  78                 const char *super_prefix = get_super_prefix();
  79                 if (!super_prefix) {
  80                         super_prefix_len = 0;
  81                 } else {
  82                         int i;
  83                         for (i = 0; i < ARRAY_SIZE(buf); i++)
  84                                 strbuf_addstr(&buf[i], super_prefix);
  85                         super_prefix_len = buf[0].len;
  86                 }
  87         }
  88
  89         if (!super_prefix_len)
  90                 return path;
  91
  92         if (++idx >= ARRAY_SIZE(buf))
  93                 idx = 0;
  94
  95         strbuf_setlen(&buf[idx], super_prefix_len);
  96         strbuf_addstr(&buf[idx], path);
  97
  98         return buf[idx].buf;
  99 }
 100
 101 void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
 102                                   const char *cmd)
 103 {
 104         int i;
 105         const char **msgs = opts->msgs;
 106         const char *msg;
 107
 108         argv_array_init(&opts->msgs_to_free);
 109
 110         if (!strcmp(cmd, "checkout"))
 111                 msg = advice_commit_before_merge
 112                       ? _("Your local changes to the following files would be overwritten by checkout:\n%%s"
 113                           "Please commit your changes or stash them before you switch branches.")
 114                       : _("Your local changes to the following files would be overwritten by checkout:\n%%s");
 115         else if (!strcmp(cmd, "merge"))
 116                 msg = advice_commit_before_merge
 117                       ? _("Your local changes to the following files would be overwritten by merge:\n%%s"
 118                           "Please commit your changes or stash them before you merge.")
 119                       : _("Your local changes to the following files would be overwritten by merge:\n%%s");
 120         else
 121                 msg = advice_commit_before_merge
 122                       ? _("Your local changes to the following files would be overwritten by %s:\n%%s"
 123                           "Please commit your changes or stash them before you %s.")
 124                       : _("Your local changes to the following files would be overwritten by %s:\n%%s");
 125         msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
 126                 argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
 127
 128         msgs[ERROR_NOT_UPTODATE_DIR] =
 129                 _("Updating the following directories would lose untracked files in them:\n%s");
 130
 131         if (!strcmp(cmd, "checkout"))
 132                 msg = advice_commit_before_merge
 133                       ? _("The following untracked working tree files would be removed by checkout:\n%%s"
 134                           "Please move or remove them before you switch branches.")
 135                       : _("The following untracked working tree files would be removed by checkout:\n%%s");
 136         else if (!strcmp(cmd, "merge"))
 137                 msg = advice_commit_before_merge
 138                       ? _("The following untracked working tree files would be removed by merge:\n%%s"
 139                           "Please move or remove them before you merge.")
 140                       : _("The following untracked working tree files would be removed by merge:\n%%s");
 141         else
 142                 msg = advice_commit_before_merge
 143                       ? _("The following untracked working tree files would be removed by %s:\n%%s"
 144                           "Please move or remove them before you %s.")
 145                       : _("The following untracked working tree files would be removed by %s:\n%%s");
 146         msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] =
 147                 argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
 148
 149         if (!strcmp(cmd, "checkout"))
 150                 msg = advice_commit_before_merge
 151                       ? _("The following untracked working tree files would be overwritten by checkout:\n%%s"
 152                           "Please move or remove them before you switch branches.")
 153                       : _("The following untracked working tree files would be overwritten by checkout:\n%%s");
 154         else if (!strcmp(cmd, "merge"))
 155                 msg = advice_commit_before_merge
 156                       ? _("The following untracked working tree files would be overwritten by merge:\n%%s"
 157                           "Please move or remove them before you merge.")
 158                       : _("The following untracked working tree files would be overwritten by merge:\n%%s");
 159         else
 160                 msg = advice_commit_before_merge
 161                       ? _("The following untracked working tree files would be overwritten by %s:\n%%s"
 162                           "Please move or remove them before you %s.")
 163                       : _("The following untracked working tree files would be overwritten by %s:\n%%s");
 164         msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] =
 165                 argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
 166
 167         /*
 168          * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
 169          * cannot easily display it as a list.
 170          */
 171         msgs[ERROR_BIND_OVERLAP] = _("Entry '%s' overlaps with '%s'.  Cannot bind.");
 172
 173         msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
 174                 _("Cannot update sparse checkout: the following entries are not up to date:\n%s");
 175         msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
 176                 _("The following working tree files would be overwritten by sparse checkout update:\n%s");
 177         msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
 178                 _("The following working tree files would be removed by sparse checkout update:\n%s");
 179         msgs[ERROR_WOULD_LOSE_SUBMODULE] =
 180                 _("Cannot update submodule:\n%s");
 181
 182         opts->show_all_errors = 1;
 183         /* rejected paths may not have a static buffer */
 184         for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
 185                 opts->unpack_rejects[i].strdup_strings = 1;
 186 }
 187
 188 void clear_unpack_trees_porcelain(struct unpack_trees_options *opts)
 189 {
 190         argv_array_clear(&opts->msgs_to_free);
 191         memset(opts->msgs, 0, sizeof(opts->msgs));
 192 }
 193
 194 static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
 195                          unsigned int set, unsigned int clear)
 196 {
 197         clear |= CE_HASHED;
 198
 199         if (set & CE_REMOVE)
 200                 set |= CE_WT_REMOVE;
 201
 202         ce->ce_flags = (ce->ce_flags & ~clear) | set;
 203         return add_index_entry(&o->result, ce,
 204                                ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 205 }
 206
 207 static struct cache_entry *dup_entry(const struct cache_entry *ce)
 208 {
 209         unsigned int size = ce_size(ce);
 210         struct cache_entry *new_entry = xmalloc(size);
 211
 212         memcpy(new_entry, ce, size);
 213         return new_entry;
 214 }
 215
 216 static void add_entry(struct unpack_trees_options *o,
 217                       const struct cache_entry *ce,
 218                       unsigned int set, unsigned int clear)
 219 {
 220         do_add_entry(o, dup_entry(ce), set, clear);
 221 }
 222
 223 /*
 224  * add error messages on path <path>
 225  * corresponding to the type <e> with the message <msg>
 226  * indicating if it should be display in porcelain or not
 227  */
 228 static int add_rejected_path(struct unpack_trees_options *o,
 229                              enum unpack_trees_error_types e,
 230                              const char *path)
 231 {
 232         if (!o->show_all_errors)
 233                 return error(ERRORMSG(o, e), super_prefixed(path));
 234
 235         /*
 236          * Otherwise, insert in a list for future display by
 237          * display_error_msgs()
 238          */
 239         string_list_append(&o->unpack_rejects[e], path);
 240         return -1;
 241 }
 242
 243 /*
 244  * display all the error messages stored in a nice way
 245  */
 246 static void display_error_msgs(struct unpack_trees_options *o)
 247 {
 248         int e, i;
 249         int something_displayed = 0;
 250         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
 251                 struct string_list *rejects = &o->unpack_rejects[e];
 252                 if (rejects->nr > 0) {
 253                         struct strbuf path = STRBUF_INIT;
 254                         something_displayed = 1;
 255                         for (i = 0; i < rejects->nr; i++)
 256                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
 257                         error(ERRORMSG(o, e), super_prefixed(path.buf));
 258                         strbuf_release(&path);
 259                 }
 260                 string_list_clear(rejects, 0);
 261         }
 262         if (something_displayed)
 263                 fprintf(stderr, _("Aborting\n"));
 264 }
 265
 266 static int check_submodule_move_head(const struct cache_entry *ce,
 267                                      const char *old_id,
 268                                      const char *new_id,
 269                                      struct unpack_trees_options *o)
 270 {
 271         unsigned flags = SUBMODULE_MOVE_HEAD_DRY_RUN;
 272         const struct submodule *sub = submodule_from_ce(ce);
 273
 274         if (!sub)
 275                 return 0;
 276
 277         if (o->reset)
 278                 flags |= SUBMODULE_MOVE_HEAD_FORCE;
 279
 280         if (submodule_move_head(ce->name, old_id, new_id, flags))
 281                 return o->gently ? -1 :
 282                                    add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
 283         return 0;
 284 }
 285
 286 /*
 287  * Preform the loading of the repository's gitmodules file.  This function is
 288  * used by 'check_update()' to perform loading of the gitmodules file in two
 289  * differnt situations:
 290  * (1) before removing entries from the working tree if the gitmodules file has
 291  *     been marked for removal.  This situation is specified by 'state' == NULL.
 292  * (2) before checking out entries to the working tree if the gitmodules file
 293  *     has been marked for update.  This situation is specified by 'state' != NULL.
 294  */
 295 static void load_gitmodules_file(struct index_state *index,
 296                                  struct checkout *state)
 297 {
 298         int pos = index_name_pos(index, GITMODULES_FILE, strlen(GITMODULES_FILE));
 299
 300         if (pos >= 0) {
 301                 struct cache_entry *ce = index->cache[pos];
 302                 if (!state && ce->ce_flags & CE_WT_REMOVE) {
 303                         repo_read_gitmodules(the_repository);
 304                 } else if (state && (ce->ce_flags & CE_UPDATE)) {
 305                         submodule_free(the_repository);
 306                         checkout_entry(ce, state, NULL);
 307                         repo_read_gitmodules(the_repository);
 308                 }
 309         }
 310 }
 311
 312 /*
 313  * Unlink the last component and schedule the leading directories for
 314  * removal, such that empty directories get removed.
 315  */
 316 static void unlink_entry(const struct cache_entry *ce)
 317 {
 318         const struct submodule *sub = submodule_from_ce(ce);
 319         if (sub) {
 320                 /* state.force is set at the caller. */
 321                 submodule_move_head(ce->name, "HEAD", NULL,
 322                                     SUBMODULE_MOVE_HEAD_FORCE);
 323         }
 324         if (!check_leading_path(ce->name, ce_namelen(ce)))
 325                 return;
 326         if (remove_or_warn(ce->ce_mode, ce->name))
 327                 return;
 328         schedule_dir_for_removal(ce->name, ce_namelen(ce));
 329 }
 330
 331 static struct progress *get_progress(struct unpack_trees_options *o)
 332 {
 333         unsigned cnt = 0, total = 0;
 334         struct index_state *index = &o->result;
 335
 336         if (!o->update || !o->verbose_update)
 337                 return NULL;
 338
 339         for (; cnt < index->cache_nr; cnt++) {
 340                 const struct cache_entry *ce = index->cache[cnt];
 341                 if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
 342                         total++;
 343         }
 344
 345         return start_delayed_progress(_("Checking out files"), total);
 346 }
 347
 348 static int check_updates(struct unpack_trees_options *o)
 349 {
 350         unsigned cnt = 0;
 351         int errs = 0;
 352         struct progress *progress = NULL;
 353         struct index_state *index = &o->result;
 354         struct checkout state = CHECKOUT_INIT;
 355         int i;
 356
 357         state.force = 1;
 358         state.quiet = 1;
 359         state.refresh_cache = 1;
 360         state.istate = index;
 361
 362         progress = get_progress(o);
 363
 364         if (o->update)
 365                 git_attr_set_direction(GIT_ATTR_CHECKOUT, index);
 366
 367         if (should_update_submodules() && o->update && !o->dry_run)
 368                 load_gitmodules_file(index, NULL);
 369
 370         for (i = 0; i < index->cache_nr; i++) {
 371                 const struct cache_entry *ce = index->cache[i];
 372
 373                 if (ce->ce_flags & CE_WT_REMOVE) {
 374                         display_progress(progress, ++cnt);
 375                         if (o->update && !o->dry_run)
 376                                 unlink_entry(ce);
 377                 }
 378         }
 379         remove_marked_cache_entries(index);
 380         remove_scheduled_dirs();
 381
 382         if (should_update_submodules() && o->update && !o->dry_run)
 383                 load_gitmodules_file(index, &state);
 384
 385         enable_delayed_checkout(&state);
 386         if (repository_format_partial_clone && o->update && !o->dry_run) {
 387                 /*
 388                  * Prefetch the objects that are to be checked out in the loop
 389                  * below.
 390                  */
 391                 struct oid_array to_fetch = OID_ARRAY_INIT;
 392                 int fetch_if_missing_store = fetch_if_missing;
 393                 fetch_if_missing = 0;
 394                 for (i = 0; i < index->cache_nr; i++) {
 395                         struct cache_entry *ce = index->cache[i];
 396                         if ((ce->ce_flags & CE_UPDATE) &&
 397                             !S_ISGITLINK(ce->ce_mode)) {
 398                                 if (!has_object_file(&ce->oid))
 399                                         oid_array_append(&to_fetch, &ce->oid);
 400                         }
 401                 }
 402                 if (to_fetch.nr)
 403                         fetch_objects(repository_format_partial_clone,
 404                                       &to_fetch);
 405                 fetch_if_missing = fetch_if_missing_store;
 406                 oid_array_clear(&to_fetch);
 407         }
 408         for (i = 0; i < index->cache_nr; i++) {
 409                 struct cache_entry *ce = index->cache[i];
 410
 411                 if (ce->ce_flags & CE_UPDATE) {
 412                         if (ce->ce_flags & CE_WT_REMOVE)
 413                                 BUG("both update and delete flags are set on %s",
 414                                     ce->name);
 415                         display_progress(progress, ++cnt);
 416                         ce->ce_flags &= ~CE_UPDATE;
 417                         if (o->update && !o->dry_run) {
 418                                 errs |= checkout_entry(ce, &state, NULL);
 419                         }
 420                 }
 421         }
 422         stop_progress(&progress);
 423         errs |= finish_delayed_checkout(&state);
 424         if (o->update)
 425                 git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
 426         return errs != 0;
 427 }
 428
 429 static int verify_uptodate_sparse(const struct cache_entry *ce,
 430                                   struct unpack_trees_options *o);
 431 static int verify_absent_sparse(const struct cache_entry *ce,
 432                                 enum unpack_trees_error_types,
 433                                 struct unpack_trees_options *o);
 434
 435 static int apply_sparse_checkout(struct index_state *istate,
 436                                  struct cache_entry *ce,
 437                                  struct unpack_trees_options *o)
 438 {
 439         int was_skip_worktree = ce_skip_worktree(ce);
 440
 441         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
 442                 ce->ce_flags |= CE_SKIP_WORKTREE;
 443         else
 444                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
 445         if (was_skip_worktree != ce_skip_worktree(ce)) {
 446                 ce->ce_flags |= CE_UPDATE_IN_BASE;
 447                 mark_fsmonitor_invalid(istate, ce);
 448                 istate->cache_changed |= CE_ENTRY_CHANGED;
 449         }
 450
 451         /*
 452          * if (!was_skip_worktree && !ce_skip_worktree()) {
 453          *      This is perfectly normal. Move on;
 454          * }
 455          */
 456
 457         /*
 458          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
 459          * area as a result of ce_skip_worktree() shortcuts in
 460          * verify_absent() and verify_uptodate().
 461          * Make sure they don't modify worktree if they are already
 462          * outside checkout area
 463          */
 464         if (was_skip_worktree && ce_skip_worktree(ce)) {
 465                 ce->ce_flags &= ~CE_UPDATE;
 466
 467                 /*
 468                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
 469                  * on to get that file removed from both index and worktree.
 470                  * If that file is already outside worktree area, don't
 471                  * bother remove it.
 472                  */
 473                 if (ce->ce_flags & CE_REMOVE)
 474                         ce->ce_flags &= ~CE_WT_REMOVE;
 475         }
 476
 477         if (!was_skip_worktree && ce_skip_worktree(ce)) {
 478                 /*
 479                  * If CE_UPDATE is set, verify_uptodate() must be called already
 480                  * also stat info may have lost after merged_entry() so calling
 481                  * verify_uptodate() again may fail
 482                  */
 483                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
 484                         return -1;
 485                 ce->ce_flags |= CE_WT_REMOVE;
 486                 ce->ce_flags &= ~CE_UPDATE;
 487         }
 488         if (was_skip_worktree && !ce_skip_worktree(ce)) {
 489                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
 490                         return -1;
 491                 ce->ce_flags |= CE_UPDATE;
 492         }
 493         return 0;
 494 }
 495
 496 static inline int call_unpack_fn(const struct cache_entry * const *src,
 497                                  struct unpack_trees_options *o)
 498 {
 499         int ret = o->fn(src, o);
 500         if (ret > 0)
 501                 ret = 0;
 502         return ret;
 503 }
 504
 505 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
 506 {
 507         ce->ce_flags |= CE_UNPACKED;
 508
 509         if (o->cache_bottom < o->src_index->cache_nr &&
 510             o->src_index->cache[o->cache_bottom] == ce) {
 511                 int bottom = o->cache_bottom;
 512                 while (bottom < o->src_index->cache_nr &&
 513                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
 514                         bottom++;
 515                 o->cache_bottom = bottom;
 516         }
 517 }
 518
 519 static void mark_all_ce_unused(struct index_state *index)
 520 {
 521         int i;
 522         for (i = 0; i < index->cache_nr; i++)
 523                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
 524 }
 525
 526 static int locate_in_src_index(const struct cache_entry *ce,
 527                                struct unpack_trees_options *o)
 528 {
 529         struct index_state *index = o->src_index;
 530         int len = ce_namelen(ce);
 531         int pos = index_name_pos(index, ce->name, len);
 532         if (pos < 0)
 533                 pos = -1 - pos;
 534         return pos;
 535 }
 536
 537 /*
 538  * We call unpack_index_entry() with an unmerged cache entry
 539  * only in diff-index, and it wants a single callback.  Skip
 540  * the other unmerged entry with the same name.
 541  */
 542 static void mark_ce_used_same_name(struct cache_entry *ce,
 543                                    struct unpack_trees_options *o)
 544 {
 545         struct index_state *index = o->src_index;
 546         int len = ce_namelen(ce);
 547         int pos;
 548
 549         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
 550                 struct cache_entry *next = index->cache[pos];
 551                 if (len != ce_namelen(next) ||
 552                     memcmp(ce->name, next->name, len))
 553                         break;
 554                 mark_ce_used(next, o);
 555         }
 556 }
 557
 558 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
 559 {
 560         const struct index_state *index = o->src_index;
 561         int pos = o->cache_bottom;
 562
 563         while (pos < index->cache_nr) {
 564                 struct cache_entry *ce = index->cache[pos];
 565                 if (!(ce->ce_flags & CE_UNPACKED))
 566                         return ce;
 567                 pos++;
 568         }
 569         return NULL;
 570 }
 571
 572 static void add_same_unmerged(const struct cache_entry *ce,
 573                               struct unpack_trees_options *o)
 574 {
 575         struct index_state *index = o->src_index;
 576         int len = ce_namelen(ce);
 577         int pos = index_name_pos(index, ce->name, len);
 578
 579         if (0 <= pos)
 580                 die("programming error in a caller of mark_ce_used_same_name");
 581         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
 582                 struct cache_entry *next = index->cache[pos];
 583                 if (len != ce_namelen(next) ||
 584                     memcmp(ce->name, next->name, len))
 585                         break;
 586                 add_entry(o, next, 0, 0);
 587                 mark_ce_used(next, o);
 588         }
 589 }
 590
 591 static int unpack_index_entry(struct cache_entry *ce,
 592                               struct unpack_trees_options *o)
 593 {
 594         const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 595         int ret;
 596
 597         src[0] = ce;
 598
 599         mark_ce_used(ce, o);
 600         if (ce_stage(ce)) {
 601                 if (o->skip_unmerged) {
 602                         add_entry(o, ce, 0, 0);
 603                         return 0;
 604                 }
 605         }
 606         ret = call_unpack_fn(src, o);
 607         if (ce_stage(ce))
 608                 mark_ce_used_same_name(ce, o);
 609         return ret;
 610 }
 611
 612 static int find_cache_pos(struct traverse_info *, const struct name_entry *);
 613
 614 static void restore_cache_bottom(struct traverse_info *info, int bottom)
 615 {
 616         struct unpack_trees_options *o = info->data;
 617
 618         if (o->diff_index_cached)
 619                 return;
 620         o->cache_bottom = bottom;
 621 }
 622
 623 static int switch_cache_bottom(struct traverse_info *info)
 624 {
 625         struct unpack_trees_options *o = info->data;
 626         int ret, pos;
 627
 628         if (o->diff_index_cached)
 629                 return 0;
 630         ret = o->cache_bottom;
 631         pos = find_cache_pos(info->prev, &info->name);
 632
 633         if (pos < -1)
 634                 o->cache_bottom = -2 - pos;
 635         else if (pos < 0)
 636                 o->cache_bottom = o->src_index->cache_nr;
 637         return ret;
 638 }
 639
 640 static inline int are_same_oid(struct name_entry *name_j, struct name_entry *name_k)
 641 {
 642         return name_j->oid && name_k->oid && !oidcmp(name_j->oid, name_k->oid);
 643 }
 644
 645 static int traverse_trees_recursive(int n, unsigned long dirmask,
 646                                     unsigned long df_conflicts,
 647                                     struct name_entry *names,
 648                                     struct traverse_info *info)
 649 {
 650         int i, ret, bottom;
 651         int nr_buf = 0;
 652         struct tree_desc t[MAX_UNPACK_TREES];
 653         void *buf[MAX_UNPACK_TREES];
 654         struct traverse_info newinfo;
 655         struct name_entry *p;
 656
 657         p = names;
 658         while (!p->mode)
 659                 p++;
 660
 661         newinfo = *info;
 662         newinfo.prev = info;
 663         newinfo.pathspec = info->pathspec;
 664         newinfo.name = *p;
 665         newinfo.pathlen += tree_entry_len(p) + 1;
 666         newinfo.df_conflicts |= df_conflicts;
 667
 668         /*
 669          * Fetch the tree from the ODB for each peer directory in the
 670          * n commits.
 671          *
 672          * For 2- and 3-way traversals, we try to avoid hitting the
 673          * ODB twice for the same OID.  This should yield a nice speed
 674          * up in checkouts and merges when the commits are similar.
 675          *
 676          * We don't bother doing the full O(n^2) search for larger n,
 677          * because wider traversals don't happen that often and we
 678          * avoid the search setup.
 679          *
 680          * When 2 peer OIDs are the same, we just copy the tree
 681          * descriptor data.  This implicitly borrows the buffer
 682          * data from the earlier cell.
 683          */
 684         for (i = 0; i < n; i++, dirmask >>= 1) {
 685                 if (i > 0 && are_same_oid(&names[i], &names[i - 1]))
 686                         t[i] = t[i - 1];
 687                 else if (i > 1 && are_same_oid(&names[i], &names[i - 2]))
 688                         t[i] = t[i - 2];
 689                 else {
 690                         const struct object_id *oid = NULL;
 691                         if (dirmask & 1)
 692                                 oid = names[i].oid;
 693                         buf[nr_buf++] = fill_tree_descriptor(t + i, oid);
 694                 }
 695         }
 696
 697         bottom = switch_cache_bottom(&newinfo);
 698         ret = traverse_trees(n, t, &newinfo);
 699         restore_cache_bottom(&newinfo, bottom);
 700
 701         for (i = 0; i < nr_buf; i++)
 702                 free(buf[i]);
 703
 704         return ret;
 705 }
 706
 707 /*
 708  * Compare the traverse-path to the cache entry without actually
 709  * having to generate the textual representation of the traverse
 710  * path.
 711  *
 712  * NOTE! This *only* compares up to the size of the traverse path
 713  * itself - the caller needs to do the final check for the cache
 714  * entry having more data at the end!
 715  */
 716 static int do_compare_entry_piecewise(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 717 {
 718         int len, pathlen, ce_len;
 719         const char *ce_name;
 720
 721         if (info->prev) {
 722                 int cmp = do_compare_entry_piecewise(ce, info->prev,
 723                                                      &info->name);
 724                 if (cmp)
 725                         return cmp;
 726         }
 727         pathlen = info->pathlen;
 728         ce_len = ce_namelen(ce);
 729
 730         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 731         if (ce_len < pathlen)
 732                 return -1;
 733
 734         ce_len -= pathlen;
 735         ce_name = ce->name + pathlen;
 736
 737         len = tree_entry_len(n);
 738         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 739 }
 740
 741 static int do_compare_entry(const struct cache_entry *ce,
 742                             const struct traverse_info *info,
 743                             const struct name_entry *n)
 744 {
 745         int len, pathlen, ce_len;
 746         const char *ce_name;
 747         int cmp;
 748
 749         /*
 750          * If we have not precomputed the traverse path, it is quicker
 751          * to avoid doing so.  But if we have precomputed it,
 752          * it is quicker to use the precomputed version.
 753          */
 754         if (!info->traverse_path)
 755                 return do_compare_entry_piecewise(ce, info, n);
 756
 757         cmp = strncmp(ce->name, info->traverse_path, info->pathlen);
 758         if (cmp)
 759                 return cmp;
 760
 761         pathlen = info->pathlen;
 762         ce_len = ce_namelen(ce);
 763
 764         if (ce_len < pathlen)
 765                 return -1;
 766
 767         ce_len -= pathlen;
 768         ce_name = ce->name + pathlen;
 769
 770         len = tree_entry_len(n);
 771         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 772 }
 773
 774 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 775 {
 776         int cmp = do_compare_entry(ce, info, n);
 777         if (cmp)
 778                 return cmp;
 779
 780         /*
 781          * Even if the beginning compared identically, the ce should
 782          * compare as bigger than a directory leading up to it!
 783          */
 784         return ce_namelen(ce) > traverse_path_len(info, n);
 785 }
 786
 787 static int ce_in_traverse_path(const struct cache_entry *ce,
 788                                const struct traverse_info *info)
 789 {
 790         if (!info->prev)
 791                 return 1;
 792         if (do_compare_entry(ce, info->prev, &info->name))
 793                 return 0;
 794         /*
 795          * If ce (blob) is the same name as the path (which is a tree
 796          * we will be descending into), it won't be inside it.
 797          */
 798         return (info->pathlen < ce_namelen(ce));
 799 }
 800
 801 static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
 802 {
 803         int len = traverse_path_len(info, n);
 804         struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
 805
 806         ce->ce_mode = create_ce_mode(n->mode);
 807         ce->ce_flags = create_ce_flags(stage);
 808         ce->ce_namelen = len;
 809         oidcpy(&ce->oid, n->oid);
 810         make_traverse_path(ce->name, info, n);
 811
 812         return ce;
 813 }
 814
 815 static int unpack_nondirectories(int n, unsigned long mask,
 816                                  unsigned long dirmask,
 817                                  struct cache_entry **src,
 818                                  const struct name_entry *names,
 819                                  const struct traverse_info *info)
 820 {
 821         int i;
 822         struct unpack_trees_options *o = info->data;
 823         unsigned long conflicts = info->df_conflicts | dirmask;
 824
 825         /* Do we have *only* directories? Nothing to do */
 826         if (mask == dirmask && !src[0])
 827                 return 0;
 828
 829         /*
 830          * Ok, we've filled in up to any potential index entry in src[0],
 831          * now do the rest.
 832          */
 833         for (i = 0; i < n; i++) {
 834                 int stage;
 835                 unsigned int bit = 1ul << i;
 836                 if (conflicts & bit) {
 837                         src[i + o->merge] = o->df_conflict_entry;
 838                         continue;
 839                 }
 840                 if (!(mask & bit))
 841                         continue;
 842                 if (!o->merge)
 843                         stage = 0;
 844                 else if (i + 1 < o->head_idx)
 845                         stage = 1;
 846                 else if (i + 1 > o->head_idx)
 847                         stage = 3;
 848                 else
 849                         stage = 2;
 850                 src[i + o->merge] = create_ce_entry(info, names + i, stage);
 851         }
 852
 853         if (o->merge) {
 854                 int rc = call_unpack_fn((const struct cache_entry * const *)src,
 855                                         o);
 856                 for (i = 0; i < n; i++) {
 857                         struct cache_entry *ce = src[i + o->merge];
 858                         if (ce != o->df_conflict_entry)
 859                                 free(ce);
 860                 }
 861                 return rc;
 862         }
 863
 864         for (i = 0; i < n; i++)
 865                 if (src[i] && src[i] != o->df_conflict_entry)
 866                         if (do_add_entry(o, src[i], 0, 0))
 867                                 return -1;
 868
 869         return 0;
 870 }
 871
 872 static int unpack_failed(struct unpack_trees_options *o, const char *message)
 873 {
 874         discard_index(&o->result);
 875         if (!o->gently && !o->exiting_early) {
 876                 if (message)
 877                         return error("%s", message);
 878                 return -1;
 879         }
 880         return -1;
 881 }
 882
 883 /*
 884  * The tree traversal is looking at name p.  If we have a matching entry,
 885  * return it.  If name p is a directory in the index, do not return
 886  * anything, as we will want to match it when the traversal descends into
 887  * the directory.
 888  */
 889 static int find_cache_pos(struct traverse_info *info,
 890                           const struct name_entry *p)
 891 {
 892         int pos;
 893         struct unpack_trees_options *o = info->data;
 894         struct index_state *index = o->src_index;
 895         int pfxlen = info->pathlen;
 896         int p_len = tree_entry_len(p);
 897
 898         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
 899                 const struct cache_entry *ce = index->cache[pos];
 900                 const char *ce_name, *ce_slash;
 901                 int cmp, ce_len;
 902
 903                 if (ce->ce_flags & CE_UNPACKED) {
 904                         /*
 905                          * cache_bottom entry is already unpacked, so
 906                          * we can never match it; don't check it
 907                          * again.
 908                          */
 909                         if (pos == o->cache_bottom)
 910                                 ++o->cache_bottom;
 911                         continue;
 912                 }
 913                 if (!ce_in_traverse_path(ce, info)) {
 914                         /*
 915                          * Check if we can skip future cache checks
 916                          * (because we're already past all possible
 917                          * entries in the traverse path).
 918                          */
 919                         if (info->traverse_path) {
 920                                 if (strncmp(ce->name, info->traverse_path,
 921                                             info->pathlen) > 0)
 922                                         break;
 923                         }
 924                         continue;
 925                 }
 926                 ce_name = ce->name + pfxlen;
 927                 ce_slash = strchr(ce_name, '/');
 928                 if (ce_slash)
 929                         ce_len = ce_slash - ce_name;
 930                 else
 931                         ce_len = ce_namelen(ce) - pfxlen;
 932                 cmp = name_compare(p->path, p_len, ce_name, ce_len);
 933                 /*
 934                  * Exact match; if we have a directory we need to
 935                  * delay returning it.
 936                  */
 937                 if (!cmp)
 938                         return ce_slash ? -2 - pos : pos;
 939                 if (0 < cmp)
 940                         continue; /* keep looking */
 941                 /*
 942                  * ce_name sorts after p->path; could it be that we
 943                  * have files under p->path directory in the index?
 944                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
 945                  * have "t/a" in the index.
 946                  */
 947                 if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
 948                     ce_name[p_len] < '/')
 949                         continue; /* keep looking */
 950                 break;
 951         }
 952         return -1;
 953 }
 954
 955 static struct cache_entry *find_cache_entry(struct traverse_info *info,
 956                                             const struct name_entry *p)
 957 {
 958         int pos = find_cache_pos(info, p);
 959         struct unpack_trees_options *o = info->data;
 960
 961         if (0 <= pos)
 962                 return o->src_index->cache[pos];
 963         else
 964                 return NULL;
 965 }
 966
 967 static void debug_path(struct traverse_info *info)
 968 {
 969         if (info->prev) {
 970                 debug_path(info->prev);
 971                 if (*info->prev->name.path)
 972                         putchar('/');
 973         }
 974         printf("%s", info->name.path);
 975 }
 976
 977 static void debug_name_entry(int i, struct name_entry *n)
 978 {
 979         printf("ent#%d %06o %s\n", i,
 980                n->path ? n->mode : 0,
 981                n->path ? n->path : "(missing)");
 982 }
 983
 984 static void debug_unpack_callback(int n,
 985                                   unsigned long mask,
 986                                   unsigned long dirmask,
 987                                   struct name_entry *names,
 988                                   struct traverse_info *info)
 989 {
 990         int i;
 991         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
 992                mask, dirmask, n);
 993         debug_path(info);
 994         putchar('\n');
 995         for (i = 0; i < n; i++)
 996                 debug_name_entry(i, names + i);
 997 }
 998
 999 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
1000 {
1001         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
1002         struct unpack_trees_options *o = info->data;
1003         const struct name_entry *p = names;
1004
1005         /* Find first entry with a real name (we could use "mask" too) */
1006         while (!p->mode)
1007                 p++;
1008
1009         if (o->debug_unpack)
1010                 debug_unpack_callback(n, mask, dirmask, names, info);
1011
1012         /* Are we supposed to look at the index too? */
1013         if (o->merge) {
1014                 while (1) {
1015                         int cmp;
1016                         struct cache_entry *ce;
1017
1018                         if (o->diff_index_cached)
1019                                 ce = next_cache_entry(o);
1020                         else
1021                                 ce = find_cache_entry(info, p);
1022
1023                         if (!ce)
1024                                 break;
1025                         cmp = compare_entry(ce, info, p);
1026                         if (cmp < 0) {
1027                                 if (unpack_index_entry(ce, o) < 0)
1028                                         return unpack_failed(o, NULL);
1029                                 continue;
1030                         }
1031                         if (!cmp) {
1032                                 if (ce_stage(ce)) {
1033                                         /*
1034                                          * If we skip unmerged index
1035                                          * entries, we'll skip this
1036                                          * entry *and* the tree
1037                                          * entries associated with it!
1038                                          */
1039                                         if (o->skip_unmerged) {
1040                                                 add_same_unmerged(ce, o);
1041                                                 return mask;
1042                                         }
1043                                 }
1044                                 src[0] = ce;
1045                         }
1046                         break;
1047                 }
1048         }
1049
1050         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
1051                 return -1;
1052
1053         if (o->merge && src[0]) {
1054                 if (ce_stage(src[0]))
1055                         mark_ce_used_same_name(src[0], o);
1056                 else
1057                         mark_ce_used(src[0], o);
1058         }
1059
1060         /* Now handle any directories.. */
1061         if (dirmask) {
1062                 /* special case: "diff-index --cached" looking at a tree */
1063                 if (o->diff_index_cached &&
1064                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
1065                         int matches;
1066                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
1067                                                                names, info);
1068                         /*
1069                          * Everything under the name matches; skip the
1070                          * entire hierarchy.  diff_index_cached codepath
1071                          * special cases D/F conflicts in such a way that
1072                          * it does not do any look-ahead, so this is safe.
1073                          */
1074                         if (matches) {
1075                                 o->cache_bottom += matches;
1076                                 return mask;
1077                         }
1078                 }
1079
1080                 if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
1081                                              names, info) < 0)
1082                         return -1;
1083                 return mask;
1084         }
1085
1086         return mask;
1087 }
1088
1089 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
1090                             struct strbuf *prefix,
1091                             int select_mask, int clear_mask,
1092                             struct exclude_list *el, int defval);
1093
1094 /* Whole directory matching */
1095 static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
1096                               struct strbuf *prefix,
1097                               char *basename,
1098                               int select_mask, int clear_mask,
1099                               struct exclude_list *el, int defval)
1100 {
1101         struct cache_entry **cache_end;
1102         int dtype = DT_DIR;
1103         int ret = is_excluded_from_list(prefix->buf, prefix->len,
1104                                         basename, &dtype, el, &the_index);
1105         int rc;
1106
1107         strbuf_addch(prefix, '/');
1108
1109         /* If undecided, use matching result of parent dir in defval */
1110         if (ret < 0)
1111                 ret = defval;
1112
1113         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
1114                 struct cache_entry *ce = *cache_end;
1115                 if (strncmp(ce->name, prefix->buf, prefix->len))
1116                         break;
1117         }
1118
1119         /*
1120          * TODO: check el, if there are no patterns that may conflict
1121          * with ret (iow, we know in advance the incl/excl
1122          * decision for the entire directory), clear flag here without
1123          * calling clear_ce_flags_1(). That function will call
1124          * the expensive is_excluded_from_list() on every entry.
1125          */
1126         rc = clear_ce_flags_1(cache, cache_end - cache,
1127                               prefix,
1128                               select_mask, clear_mask,
1129                               el, ret);
1130         strbuf_setlen(prefix, prefix->len - 1);
1131         return rc;
1132 }
1133
1134 /*
1135  * Traverse the index, find every entry that matches according to
1136  * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
1137  * number of traversed entries.
1138  *
1139  * If select_mask is non-zero, only entries whose ce_flags has on of
1140  * those bits enabled are traversed.
1141  *
1142  * cache        : pointer to an index entry
1143  * prefix_len   : an offset to its path
1144  *
1145  * The current path ("prefix") including the trailing '/' is
1146  *   cache[0]->name[0..(prefix_len-1)]
1147  * Top level path has prefix_len zero.
1148  */
1149 static int clear_ce_flags_1(struct cache_entry **cache, int nr,
1150                             struct strbuf *prefix,
1151                             int select_mask, int clear_mask,
1152                             struct exclude_list *el, int defval)
1153 {
1154         struct cache_entry **cache_end = cache + nr;
1155
1156         /*
1157          * Process all entries that have the given prefix and meet
1158          * select_mask condition
1159          */
1160         while(cache != cache_end) {
1161                 struct cache_entry *ce = *cache;
1162                 const char *name, *slash;
1163                 int len, dtype, ret;
1164
1165                 if (select_mask && !(ce->ce_flags & select_mask)) {
1166                         cache++;
1167                         continue;
1168                 }
1169
1170                 if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
1171                         break;
1172
1173                 name = ce->name + prefix->len;
1174                 slash = strchr(name, '/');
1175
1176                 /* If it's a directory, try whole directory match first */
1177                 if (slash) {
1178                         int processed;
1179
1180                         len = slash - name;
1181                         strbuf_add(prefix, name, len);
1182
1183                         processed = clear_ce_flags_dir(cache, cache_end - cache,
1184                                                        prefix,
1185                                                        prefix->buf + prefix->len - len,
1186                                                        select_mask, clear_mask,
1187                                                        el, defval);
1188
1189                         /* clear_c_f_dir eats a whole dir already? */
1190                         if (processed) {
1191                                 cache += processed;
1192                                 strbuf_setlen(prefix, prefix->len - len);
1193                                 continue;
1194                         }
1195
1196                         strbuf_addch(prefix, '/');
1197                         cache += clear_ce_flags_1(cache, cache_end - cache,
1198                                                   prefix,
1199                                                   select_mask, clear_mask, el, defval);
1200                         strbuf_setlen(prefix, prefix->len - len - 1);
1201                         continue;
1202                 }
1203
1204                 /* Non-directory */
1205                 dtype = ce_to_dtype(ce);
1206                 ret = is_excluded_from_list(ce->name, ce_namelen(ce),
1207                                             name, &dtype, el, &the_index);
1208                 if (ret < 0)
1209                         ret = defval;
1210                 if (ret > 0)
1211                         ce->ce_flags &= ~clear_mask;
1212                 cache++;
1213         }
1214         return nr - (cache_end - cache);
1215 }
1216
1217 static int clear_ce_flags(struct cache_entry **cache, int nr,
1218                             int select_mask, int clear_mask,
1219                             struct exclude_list *el)
1220 {
1221         static struct strbuf prefix = STRBUF_INIT;
1222
1223         strbuf_reset(&prefix);
1224
1225         return clear_ce_flags_1(cache, nr,
1226                                 &prefix,
1227                                 select_mask, clear_mask,
1228                                 el, 0);
1229 }
1230
1231 /*
1232  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
1233  */
1234 static void mark_new_skip_worktree(struct exclude_list *el,
1235                                    struct index_state *the_index,
1236                                    int select_flag, int skip_wt_flag)
1237 {
1238         int i;
1239
1240         /*
1241          * 1. Pretend the narrowest worktree: only unmerged entries
1242          * are checked out
1243          */
1244         for (i = 0; i < the_index->cache_nr; i++) {
1245                 struct cache_entry *ce = the_index->cache[i];
1246
1247                 if (select_flag && !(ce->ce_flags & select_flag))
1248                         continue;
1249
1250                 if (!ce_stage(ce) && !(ce->ce_flags & CE_CONFLICTED))
1251                         ce->ce_flags |= skip_wt_flag;
1252                 else
1253                         ce->ce_flags &= ~skip_wt_flag;
1254         }
1255
1256         /*
1257          * 2. Widen worktree according to sparse-checkout file.
1258          * Matched entries will have skip_wt_flag cleared (i.e. "in")
1259          */
1260         clear_ce_flags(the_index->cache, the_index->cache_nr,
1261                        select_flag, skip_wt_flag, el);
1262 }
1263
1264 static int verify_absent(const struct cache_entry *,
1265                          enum unpack_trees_error_types,
1266                          struct unpack_trees_options *);
1267 /*
1268  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1269  * resulting index, -2 on failure to reflect the changes to the work tree.
1270  *
1271  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1272  */
1273 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1274 {
1275         int i, ret;
1276         static struct cache_entry *dfc;
1277         struct exclude_list el;
1278
1279         if (len > MAX_UNPACK_TREES)
1280                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1281
1282         memset(&el, 0, sizeof(el));
1283         if (!core_apply_sparse_checkout || !o->update)
1284                 o->skip_sparse_checkout = 1;
1285         if (!o->skip_sparse_checkout) {
1286                 char *sparse = git_pathdup("info/sparse-checkout");
1287                 if (add_excludes_from_file_to_list(sparse, "", 0, &el, NULL) < 0)
1288                         o->skip_sparse_checkout = 1;
1289                 else
1290                         o->el = &el;
1291                 free(sparse);
1292         }
1293
1294         memset(&o->result, 0, sizeof(o->result));
1295         o->result.initialized = 1;
1296         o->result.timestamp.sec = o->src_index->timestamp.sec;
1297         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1298         o->result.version = o->src_index->version;
1299         if (!o->src_index->split_index) {
1300                 o->result.split_index = NULL;
1301         } else if (o->src_index == o->dst_index) {
1302                 /*
1303                  * o->dst_index (and thus o->src_index) will be discarded
1304                  * and overwritten with o->result at the end of this function,
1305                  * so just use src_index's split_index to avoid having to
1306                  * create a new one.
1307                  */
1308                 o->result.split_index = o->src_index->split_index;
1309                 o->result.split_index->refcount++;
1310         } else {
1311                 o->result.split_index = init_split_index(&o->result);
1312         }
1313         oidcpy(&o->result.oid, &o->src_index->oid);
1314         o->merge_size = len;
1315         mark_all_ce_unused(o->src_index);
1316
1317         /*
1318          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1319          */
1320         if (!o->skip_sparse_checkout)
1321                 mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1322
1323         if (!dfc)
1324                 dfc = xcalloc(1, cache_entry_size(0));
1325         o->df_conflict_entry = dfc;
1326
1327         if (len) {
1328                 const char *prefix = o->prefix ? o->prefix : "";
1329                 struct traverse_info info;
1330
1331                 setup_traverse_info(&info, prefix);
1332                 info.fn = unpack_callback;
1333                 info.data = o;
1334                 info.show_all_errors = o->show_all_errors;
1335                 info.pathspec = o->pathspec;
1336
1337                 if (o->prefix) {
1338                         /*
1339                          * Unpack existing index entries that sort before the
1340                          * prefix the tree is spliced into.  Note that o->merge
1341                          * is always true in this case.
1342                          */
1343                         while (1) {
1344                                 struct cache_entry *ce = next_cache_entry(o);
1345                                 if (!ce)
1346                                         break;
1347                                 if (ce_in_traverse_path(ce, &info))
1348                                         break;
1349                                 if (unpack_index_entry(ce, o) < 0)
1350                                         goto return_failed;
1351                         }
1352                 }
1353
1354                 if (traverse_trees(len, t, &info) < 0)
1355                         goto return_failed;
1356         }
1357
1358         /* Any left-over entries in the index? */
1359         if (o->merge) {
1360                 while (1) {
1361                         struct cache_entry *ce = next_cache_entry(o);
1362                         if (!ce)
1363                                 break;
1364                         if (unpack_index_entry(ce, o) < 0)
1365                                 goto return_failed;
1366                 }
1367         }
1368         mark_all_ce_unused(o->src_index);
1369
1370         if (o->trivial_merges_only && o->nontrivial_merge) {
1371                 ret = unpack_failed(o, "Merge requires file-level merging");
1372                 goto done;
1373         }
1374
1375         if (!o->skip_sparse_checkout) {
1376                 int empty_worktree = 1;
1377
1378                 /*
1379                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1380                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1381                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1382                  */
1383                 mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1384
1385                 ret = 0;
1386                 for (i = 0; i < o->result.cache_nr; i++) {
1387                         struct cache_entry *ce = o->result.cache[i];
1388
1389                         /*
1390                          * Entries marked with CE_ADDED in merged_entry() do not have
1391                          * verify_absent() check (the check is effectively disabled
1392                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1393                          *
1394                          * Do the real check now because we have had
1395                          * correct CE_NEW_SKIP_WORKTREE
1396                          */
1397                         if (ce->ce_flags & CE_ADDED &&
1398                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1399                                 if (!o->show_all_errors)
1400                                         goto return_failed;
1401                                 ret = -1;
1402                         }
1403
1404                         if (apply_sparse_checkout(&o->result, ce, o)) {
1405                                 if (!o->show_all_errors)
1406                                         goto return_failed;
1407                                 ret = -1;
1408                         }
1409                         if (!ce_skip_worktree(ce))
1410                                 empty_worktree = 0;
1411
1412                 }
1413                 if (ret < 0)
1414                         goto return_failed;
1415                 /*
1416                  * Sparse checkout is meant to narrow down checkout area
1417                  * but it does not make sense to narrow down to empty working
1418                  * tree. This is usually a mistake in sparse checkout rules.
1419                  * Do not allow users to do that.
1420                  */
1421                 if (o->result.cache_nr && empty_worktree) {
1422                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1423                         goto done;
1424                 }
1425         }
1426
1427         ret = check_updates(o) ? (-2) : 0;
1428         if (o->dst_index) {
1429                 if (!ret) {
1430                         if (!o->result.cache_tree)
1431                                 o->result.cache_tree = cache_tree();
1432                         if (!cache_tree_fully_valid(o->result.cache_tree))
1433                                 cache_tree_update(&o->result,
1434                                                   WRITE_TREE_SILENT |
1435                                                   WRITE_TREE_REPAIR);
1436                 }
1437                 move_index_extensions(&o->result, o->src_index);
1438                 discard_index(o->dst_index);
1439                 *o->dst_index = o->result;
1440         } else {
1441                 discard_index(&o->result);
1442         }
1443         o->src_index = NULL;
1444
1445 done:
1446         clear_exclude_list(&el);
1447         return ret;
1448
1449 return_failed:
1450         if (o->show_all_errors)
1451                 display_error_msgs(o);
1452         mark_all_ce_unused(o->src_index);
1453         ret = unpack_failed(o, NULL);
1454         if (o->exiting_early)
1455                 ret = 0;
1456         goto done;
1457 }
1458
1459 /* Here come the merge functions */
1460
1461 static int reject_merge(const struct cache_entry *ce,
1462                         struct unpack_trees_options *o)
1463 {
1464         return o->gently ? -1 :
1465                 add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1466 }
1467
1468 static int same(const struct cache_entry *a, const struct cache_entry *b)
1469 {
1470         if (!!a != !!b)
1471                 return 0;
1472         if (!a && !b)
1473                 return 1;
1474         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1475                 return 0;
1476         return a->ce_mode == b->ce_mode &&
1477                !oidcmp(&a->oid, &b->oid);
1478 }
1479
1480
1481 /*
1482  * When a CE gets turned into an unmerged entry, we
1483  * want it to be up-to-date
1484  */
1485 static int verify_uptodate_1(const struct cache_entry *ce,
1486                              struct unpack_trees_options *o,
1487                              enum unpack_trees_error_types error_type)
1488 {
1489         struct stat st;
1490
1491         if (o->index_only)
1492                 return 0;
1493
1494         /*
1495          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1496          * if this entry is truly up-to-date because this file may be
1497          * overwritten.
1498          */
1499         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1500                 ; /* keep checking */
1501         else if (o->reset || ce_uptodate(ce))
1502                 return 0;
1503
1504         if (!lstat(ce->name, &st)) {
1505                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1506                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1507
1508                 if (submodule_from_ce(ce)) {
1509                         int r = check_submodule_move_head(ce,
1510                                 "HEAD", oid_to_hex(&ce->oid), o);
1511                         if (r)
1512                                 return o->gently ? -1 :
1513                                         add_rejected_path(o, error_type, ce->name);
1514                         return 0;
1515                 }
1516
1517                 if (!changed)
1518                         return 0;
1519                 /*
1520                  * Historic default policy was to allow submodule to be out
1521                  * of sync wrt the superproject index. If the submodule was
1522                  * not considered interesting above, we don't care here.
1523                  */
1524                 if (S_ISGITLINK(ce->ce_mode))
1525                         return 0;
1526
1527                 errno = 0;
1528         }
1529         if (errno == ENOENT)
1530                 return 0;
1531         return o->gently ? -1 :
1532                 add_rejected_path(o, error_type, ce->name);
1533 }
1534
1535 int verify_uptodate(const struct cache_entry *ce,
1536                     struct unpack_trees_options *o)
1537 {
1538         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1539                 return 0;
1540         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1541 }
1542
1543 static int verify_uptodate_sparse(const struct cache_entry *ce,
1544                                   struct unpack_trees_options *o)
1545 {
1546         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1547 }
1548
1549 static void invalidate_ce_path(const struct cache_entry *ce,
1550                                struct unpack_trees_options *o)
1551 {
1552         if (!ce)
1553                 return;
1554         cache_tree_invalidate_path(o->src_index, ce->name);
1555         untracked_cache_invalidate_path(o->src_index, ce->name, 1);
1556 }
1557
1558 /*
1559  * Check that checking out ce->sha1 in subdir ce->name is not
1560  * going to overwrite any working files.
1561  *
1562  * Currently, git does not checkout subprojects during a superproject
1563  * checkout, so it is not going to overwrite anything.
1564  */
1565 static int verify_clean_submodule(const char *old_sha1,
1566                                   const struct cache_entry *ce,
1567                                   enum unpack_trees_error_types error_type,
1568                                   struct unpack_trees_options *o)
1569 {
1570         if (!submodule_from_ce(ce))
1571                 return 0;
1572
1573         return check_submodule_move_head(ce, old_sha1,
1574                                          oid_to_hex(&ce->oid), o);
1575 }
1576
1577 static int verify_clean_subdirectory(const struct cache_entry *ce,
1578                                      enum unpack_trees_error_types error_type,
1579                                      struct unpack_trees_options *o)
1580 {
1581         /*
1582          * we are about to extract "ce->name"; we would not want to lose
1583          * anything in the existing directory there.
1584          */
1585         int namelen;
1586         int i;
1587         struct dir_struct d;
1588         char *pathbuf;
1589         int cnt = 0;
1590
1591         if (S_ISGITLINK(ce->ce_mode)) {
1592                 struct object_id oid;
1593                 int sub_head = resolve_gitlink_ref(ce->name, "HEAD", &oid);
1594                 /*
1595                  * If we are not going to update the submodule, then
1596                  * we don't care.
1597                  */
1598                 if (!sub_head && !oidcmp(&oid, &ce->oid))
1599                         return 0;
1600                 return verify_clean_submodule(sub_head ? NULL : oid_to_hex(&oid),
1601                                               ce, error_type, o);
1602         }
1603
1604         /*
1605          * First let's make sure we do not have a local modification
1606          * in that directory.
1607          */
1608         namelen = ce_namelen(ce);
1609         for (i = locate_in_src_index(ce, o);
1610              i < o->src_index->cache_nr;
1611              i++) {
1612                 struct cache_entry *ce2 = o->src_index->cache[i];
1613                 int len = ce_namelen(ce2);
1614                 if (len < namelen ||
1615                     strncmp(ce->name, ce2->name, namelen) ||
1616                     ce2->name[namelen] != '/')
1617                         break;
1618                 /*
1619                  * ce2->name is an entry in the subdirectory to be
1620                  * removed.
1621                  */
1622                 if (!ce_stage(ce2)) {
1623                         if (verify_uptodate(ce2, o))
1624                                 return -1;
1625                         add_entry(o, ce2, CE_REMOVE, 0);
1626                         mark_ce_used(ce2, o);
1627                 }
1628                 cnt++;
1629         }
1630
1631         /*
1632          * Then we need to make sure that we do not lose a locally
1633          * present file that is not ignored.
1634          */
1635         pathbuf = xstrfmt("%.*s/", namelen, ce->name);
1636
1637         memset(&d, 0, sizeof(d));
1638         if (o->dir)
1639                 d.exclude_per_dir = o->dir->exclude_per_dir;
1640         i = read_directory(&d, &the_index, pathbuf, namelen+1, NULL);
1641         if (i)
1642                 return o->gently ? -1 :
1643                         add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1644         free(pathbuf);
1645         return cnt;
1646 }
1647
1648 /*
1649  * This gets called when there was no index entry for the tree entry 'dst',
1650  * but we found a file in the working tree that 'lstat()' said was fine,
1651  * and we're on a case-insensitive filesystem.
1652  *
1653  * See if we can find a case-insensitive match in the index that also
1654  * matches the stat information, and assume it's that other file!
1655  */
1656 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1657 {
1658         const struct cache_entry *src;
1659
1660         src = index_file_exists(o->src_index, name, len, 1);
1661         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1662 }
1663
1664 static int check_ok_to_remove(const char *name, int len, int dtype,
1665                               const struct cache_entry *ce, struct stat *st,
1666                               enum unpack_trees_error_types error_type,
1667                               struct unpack_trees_options *o)
1668 {
1669         const struct cache_entry *result;
1670
1671         /*
1672          * It may be that the 'lstat()' succeeded even though
1673          * target 'ce' was absent, because there is an old
1674          * entry that is different only in case..
1675          *
1676          * Ignore that lstat() if it matches.
1677          */
1678         if (ignore_case && icase_exists(o, name, len, st))
1679                 return 0;
1680
1681         if (o->dir &&
1682             is_excluded(o->dir, &the_index, name, &dtype))
1683                 /*
1684                  * ce->name is explicitly excluded, so it is Ok to
1685                  * overwrite it.
1686                  */
1687                 return 0;
1688         if (S_ISDIR(st->st_mode)) {
1689                 /*
1690                  * We are checking out path "foo" and
1691                  * found "foo/." in the working tree.
1692                  * This is tricky -- if we have modified
1693                  * files that are in "foo/" we would lose
1694                  * them.
1695                  */
1696                 if (verify_clean_subdirectory(ce, error_type, o) < 0)
1697                         return -1;
1698                 return 0;
1699         }
1700
1701         /*
1702          * The previous round may already have decided to
1703          * delete this path, which is in a subdirectory that
1704          * is being replaced with a blob.
1705          */
1706         result = index_file_exists(&o->result, name, len, 0);
1707         if (result) {
1708                 if (result->ce_flags & CE_REMOVE)
1709                         return 0;
1710         }
1711
1712         return o->gently ? -1 :
1713                 add_rejected_path(o, error_type, name);
1714 }
1715
1716 /*
1717  * We do not want to remove or overwrite a working tree file that
1718  * is not tracked, unless it is ignored.
1719  */
1720 static int verify_absent_1(const struct cache_entry *ce,
1721                            enum unpack_trees_error_types error_type,
1722                            struct unpack_trees_options *o)
1723 {
1724         int len;
1725         struct stat st;
1726
1727         if (o->index_only || o->reset || !o->update)
1728                 return 0;
1729
1730         len = check_leading_path(ce->name, ce_namelen(ce));
1731         if (!len)
1732                 return 0;
1733         else if (len > 0) {
1734                 char *path;
1735                 int ret;
1736
1737                 path = xmemdupz(ce->name, len);
1738                 if (lstat(path, &st))
1739                         ret = error_errno("cannot stat '%s'", path);
1740                 else {
1741                         if (submodule_from_ce(ce))
1742                                 ret = check_submodule_move_head(ce,
1743                                                                 oid_to_hex(&ce->oid),
1744                                                                 NULL, o);
1745                         else
1746                                 ret = check_ok_to_remove(path, len, DT_UNKNOWN, NULL,
1747                                                          &st, error_type, o);
1748                 }
1749                 free(path);
1750                 return ret;
1751         } else if (lstat(ce->name, &st)) {
1752                 if (errno != ENOENT)
1753                         return error_errno("cannot stat '%s'", ce->name);
1754                 return 0;
1755         } else {
1756                 if (submodule_from_ce(ce))
1757                         return check_submodule_move_head(ce, oid_to_hex(&ce->oid),
1758                                                          NULL, o);
1759
1760                 return check_ok_to_remove(ce->name, ce_namelen(ce),
1761                                           ce_to_dtype(ce), ce, &st,
1762                                           error_type, o);
1763         }
1764 }
1765
1766 static int verify_absent(const struct cache_entry *ce,
1767                          enum unpack_trees_error_types error_type,
1768                          struct unpack_trees_options *o)
1769 {
1770         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1771                 return 0;
1772         return verify_absent_1(ce, error_type, o);
1773 }
1774
1775 static int verify_absent_sparse(const struct cache_entry *ce,
1776                                 enum unpack_trees_error_types error_type,
1777                                 struct unpack_trees_options *o)
1778 {
1779         enum unpack_trees_error_types orphaned_error = error_type;
1780         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1781                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1782
1783         return verify_absent_1(ce, orphaned_error, o);
1784 }
1785
1786 static int merged_entry(const struct cache_entry *ce,
1787                         const struct cache_entry *old,
1788                         struct unpack_trees_options *o)
1789 {
1790         int update = CE_UPDATE;
1791         struct cache_entry *merge = dup_entry(ce);
1792
1793         if (!old) {
1794                 /*
1795                  * New index entries. In sparse checkout, the following
1796                  * verify_absent() will be delayed until after
1797                  * traverse_trees() finishes in unpack_trees(), then:
1798                  *
1799                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1800                  *  - verify_absent() be called again, this time with
1801                  *    correct CE_NEW_SKIP_WORKTREE
1802                  *
1803                  * verify_absent() call here does nothing in sparse
1804                  * checkout (i.e. o->skip_sparse_checkout == 0)
1805                  */
1806                 update |= CE_ADDED;
1807                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1808
1809                 if (verify_absent(merge,
1810                                   ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1811                         free(merge);
1812                         return -1;
1813                 }
1814                 invalidate_ce_path(merge, o);
1815
1816                 if (submodule_from_ce(ce)) {
1817                         int ret = check_submodule_move_head(ce, NULL,
1818                                                             oid_to_hex(&ce->oid),
1819                                                             o);
1820                         if (ret)
1821                                 return ret;
1822                 }
1823
1824         } else if (!(old->ce_flags & CE_CONFLICTED)) {
1825                 /*
1826                  * See if we can re-use the old CE directly?
1827                  * That way we get the uptodate stat info.
1828                  *
1829                  * This also removes the UPDATE flag on a match; otherwise
1830                  * we will end up overwriting local changes in the work tree.
1831                  */
1832                 if (same(old, merge)) {
1833                         copy_cache_entry(merge, old);
1834                         update = 0;
1835                 } else {
1836                         if (verify_uptodate(old, o)) {
1837                                 free(merge);
1838                                 return -1;
1839                         }
1840                         /* Migrate old flags over */
1841                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1842                         invalidate_ce_path(old, o);
1843                 }
1844
1845                 if (submodule_from_ce(ce)) {
1846                         int ret = check_submodule_move_head(ce, oid_to_hex(&old->oid),
1847                                                             oid_to_hex(&ce->oid),
1848                                                             o);
1849                         if (ret)
1850                                 return ret;
1851                 }
1852         } else {
1853                 /*
1854                  * Previously unmerged entry left as an existence
1855                  * marker by read_index_unmerged();
1856                  */
1857                 invalidate_ce_path(old, o);
1858         }
1859
1860         do_add_entry(o, merge, update, CE_STAGEMASK);
1861         return 1;
1862 }
1863
1864 static int deleted_entry(const struct cache_entry *ce,
1865                          const struct cache_entry *old,
1866                          struct unpack_trees_options *o)
1867 {
1868         /* Did it exist in the index? */
1869         if (!old) {
1870                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1871                         return -1;
1872                 return 0;
1873         }
1874         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1875                 return -1;
1876         add_entry(o, ce, CE_REMOVE, 0);
1877         invalidate_ce_path(ce, o);
1878         return 1;
1879 }
1880
1881 static int keep_entry(const struct cache_entry *ce,
1882                       struct unpack_trees_options *o)
1883 {
1884         add_entry(o, ce, 0, 0);
1885         return 1;
1886 }
1887
1888 #if DBRT_DEBUG
1889 static void show_stage_entry(FILE *o,
1890                              const char *label, const struct cache_entry *ce)
1891 {
1892         if (!ce)
1893                 fprintf(o, "%s (missing)\n", label);
1894         else
1895                 fprintf(o, "%s%06o %s %d\t%s\n",
1896                         label,
1897                         ce->ce_mode,
1898                         oid_to_hex(&ce->oid),
1899                         ce_stage(ce),
1900                         ce->name);
1901 }
1902 #endif
1903
1904 int threeway_merge(const struct cache_entry * const *stages,
1905                    struct unpack_trees_options *o)
1906 {
1907         const struct cache_entry *index;
1908         const struct cache_entry *head;
1909         const struct cache_entry *remote = stages[o->head_idx + 1];
1910         int count;
1911         int head_match = 0;
1912         int remote_match = 0;
1913
1914         int df_conflict_head = 0;
1915         int df_conflict_remote = 0;
1916
1917         int any_anc_missing = 0;
1918         int no_anc_exists = 1;
1919         int i;
1920
1921         for (i = 1; i < o->head_idx; i++) {
1922                 if (!stages[i] || stages[i] == o->df_conflict_entry)
1923                         any_anc_missing = 1;
1924                 else
1925                         no_anc_exists = 0;
1926         }
1927
1928         index = stages[0];
1929         head = stages[o->head_idx];
1930
1931         if (head == o->df_conflict_entry) {
1932                 df_conflict_head = 1;
1933                 head = NULL;
1934         }
1935
1936         if (remote == o->df_conflict_entry) {
1937                 df_conflict_remote = 1;
1938                 remote = NULL;
1939         }
1940
1941         /*
1942          * First, if there's a #16 situation, note that to prevent #13
1943          * and #14.
1944          */
1945         if (!same(remote, head)) {
1946                 for (i = 1; i < o->head_idx; i++) {
1947                         if (same(stages[i], head)) {
1948                                 head_match = i;
1949                         }
1950                         if (same(stages[i], remote)) {
1951                                 remote_match = i;
1952                         }
1953                 }
1954         }
1955
1956         /*
1957          * We start with cases where the index is allowed to match
1958          * something other than the head: #14(ALT) and #2ALT, where it
1959          * is permitted to match the result instead.
1960          */
1961         /* #14, #14ALT, #2ALT */
1962         if (remote && !df_conflict_head && head_match && !remote_match) {
1963                 if (index && !same(index, remote) && !same(index, head))
1964                         return reject_merge(index, o);
1965                 return merged_entry(remote, index, o);
1966         }
1967         /*
1968          * If we have an entry in the index cache, then we want to
1969          * make sure that it matches head.
1970          */
1971         if (index && !same(index, head))
1972                 return reject_merge(index, o);
1973
1974         if (head) {
1975                 /* #5ALT, #15 */
1976                 if (same(head, remote))
1977                         return merged_entry(head, index, o);
1978                 /* #13, #3ALT */
1979                 if (!df_conflict_remote && remote_match && !head_match)
1980                         return merged_entry(head, index, o);
1981         }
1982
1983         /* #1 */
1984         if (!head && !remote && any_anc_missing)
1985                 return 0;
1986
1987         /*
1988          * Under the "aggressive" rule, we resolve mostly trivial
1989          * cases that we historically had git-merge-one-file resolve.
1990          */
1991         if (o->aggressive) {
1992                 int head_deleted = !head;
1993                 int remote_deleted = !remote;
1994                 const struct cache_entry *ce = NULL;
1995
1996                 if (index)
1997                         ce = index;
1998                 else if (head)
1999                         ce = head;
2000                 else if (remote)
2001                         ce = remote;
2002                 else {
2003                         for (i = 1; i < o->head_idx; i++) {
2004                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
2005                                         ce = stages[i];
2006                                         break;
2007                                 }
2008                         }
2009                 }
2010
2011                 /*
2012                  * Deleted in both.
2013                  * Deleted in one and unchanged in the other.
2014                  */
2015                 if ((head_deleted && remote_deleted) ||
2016                     (head_deleted && remote && remote_match) ||
2017                     (remote_deleted && head && head_match)) {
2018                         if (index)
2019                                 return deleted_entry(index, index, o);
2020                         if (ce && !head_deleted) {
2021                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
2022                                         return -1;
2023                         }
2024                         return 0;
2025                 }
2026                 /*
2027                  * Added in both, identically.
2028                  */
2029                 if (no_anc_exists && head && remote && same(head, remote))
2030                         return merged_entry(head, index, o);
2031
2032         }
2033
2034         /* Below are "no merge" cases, which require that the index be
2035          * up-to-date to avoid the files getting overwritten with
2036          * conflict resolution files.
2037          */
2038         if (index) {
2039                 if (verify_uptodate(index, o))
2040                         return -1;
2041         }
2042
2043         o->nontrivial_merge = 1;
2044
2045         /* #2, #3, #4, #6, #7, #9, #10, #11. */
2046         count = 0;
2047         if (!head_match || !remote_match) {
2048                 for (i = 1; i < o->head_idx; i++) {
2049                         if (stages[i] && stages[i] != o->df_conflict_entry) {
2050                                 keep_entry(stages[i], o);
2051                                 count++;
2052                                 break;
2053                         }
2054                 }
2055         }
2056 #if DBRT_DEBUG
2057         else {
2058                 fprintf(stderr, "read-tree: warning #16 detected\n");
2059                 show_stage_entry(stderr, "head   ", stages[head_match]);
2060                 show_stage_entry(stderr, "remote ", stages[remote_match]);
2061         }
2062 #endif
2063         if (head) { count += keep_entry(head, o); }
2064         if (remote) { count += keep_entry(remote, o); }
2065         return count;
2066 }
2067
2068 /*
2069  * Two-way merge.
2070  *
2071  * The rule is to "carry forward" what is in the index without losing
2072  * information across a "fast-forward", favoring a successful merge
2073  * over a merge failure when it makes sense.  For details of the
2074  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
2075  *
2076  */
2077 int twoway_merge(const struct cache_entry * const *src,
2078                  struct unpack_trees_options *o)
2079 {
2080         const struct cache_entry *current = src[0];
2081         const struct cache_entry *oldtree = src[1];
2082         const struct cache_entry *newtree = src[2];
2083
2084         if (o->merge_size != 2)
2085                 return error("Cannot do a twoway merge of %d trees",
2086                              o->merge_size);
2087
2088         if (oldtree == o->df_conflict_entry)
2089                 oldtree = NULL;
2090         if (newtree == o->df_conflict_entry)
2091                 newtree = NULL;
2092
2093         if (current) {
2094                 if (current->ce_flags & CE_CONFLICTED) {
2095                         if (same(oldtree, newtree) || o->reset) {
2096                                 if (!newtree)
2097                                         return deleted_entry(current, current, o);
2098                                 else
2099                                         return merged_entry(newtree, current, o);
2100                         }
2101                         return reject_merge(current, o);
2102                 } else if ((!oldtree && !newtree) || /* 4 and 5 */
2103                          (!oldtree && newtree &&
2104                           same(current, newtree)) || /* 6 and 7 */
2105                          (oldtree && newtree &&
2106                           same(oldtree, newtree)) || /* 14 and 15 */
2107                          (oldtree && newtree &&
2108                           !same(oldtree, newtree) && /* 18 and 19 */
2109                           same(current, newtree))) {
2110                         return keep_entry(current, o);
2111                 } else if (oldtree && !newtree && same(current, oldtree)) {
2112                         /* 10 or 11 */
2113                         return deleted_entry(oldtree, current, o);
2114                 } else if (oldtree && newtree &&
2115                          same(current, oldtree) && !same(current, newtree)) {
2116                         /* 20 or 21 */
2117                         return merged_entry(newtree, current, o);
2118                 } else
2119                         return reject_merge(current, o);
2120         }
2121         else if (newtree) {
2122                 if (oldtree && !o->initial_checkout) {
2123                         /*
2124                          * deletion of the path was staged;
2125                          */
2126                         if (same(oldtree, newtree))
2127                                 return 1;
2128                         return reject_merge(oldtree, o);
2129                 }
2130                 return merged_entry(newtree, current, o);
2131         }
2132         return deleted_entry(oldtree, current, o);
2133 }
2134
2135 /*
2136  * Bind merge.
2137  *
2138  * Keep the index entries at stage0, collapse stage1 but make sure
2139  * stage0 does not have anything there.
2140  */
2141 int bind_merge(const struct cache_entry * const *src,
2142                struct unpack_trees_options *o)
2143 {
2144         const struct cache_entry *old = src[0];
2145         const struct cache_entry *a = src[1];
2146
2147         if (o->merge_size != 1)
2148                 return error("Cannot do a bind merge of %d trees",
2149                              o->merge_size);
2150         if (a && old)
2151                 return o->gently ? -1 :
2152                         error(ERRORMSG(o, ERROR_BIND_OVERLAP),
2153                               super_prefixed(a->name),
2154                               super_prefixed(old->name));
2155         if (!a)
2156                 return keep_entry(old, o);
2157         else
2158                 return merged_entry(a, NULL, o);
2159 }
2160
2161 /*
2162  * One-way merge.
2163  *
2164  * The rule is:
2165  * - take the stat information from stage0, take the data from stage1
2166  */
2167 int oneway_merge(const struct cache_entry * const *src,
2168                  struct unpack_trees_options *o)
2169 {
2170         const struct cache_entry *old = src[0];
2171         const struct cache_entry *a = src[1];
2172
2173         if (o->merge_size != 1)
2174                 return error("Cannot do a oneway merge of %d trees",
2175                              o->merge_size);
2176
2177         if (!a || a == o->df_conflict_entry)
2178                 return deleted_entry(old, old, o);
2179
2180         if (old && same(old, a)) {
2181                 int update = 0;
2182                 if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
2183                         struct stat st;
2184                         if (lstat(old->name, &st) ||
2185                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
2186                                 update |= CE_UPDATE;
2187                 }
2188                 if (o->update && S_ISGITLINK(old->ce_mode) &&
2189                     should_update_submodules() && !verify_uptodate(old, o))
2190                         update |= CE_UPDATE;
2191                 add_entry(o, old, update, 0);
2192                 return 0;
2193         }
2194         return merged_entry(a, old, o);
2195 }