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 void add_entry(struct unpack_trees_options *o,
 208                       const struct cache_entry *ce,
 209                       unsigned int set, unsigned int clear)
 210 {
 211         do_add_entry(o, dup_cache_entry(ce, &o->result), set, clear);
 212 }
 213
 214 /*
 215  * add error messages on path <path>
 216  * corresponding to the type <e> with the message <msg>
 217  * indicating if it should be display in porcelain or not
 218  */
 219 static int add_rejected_path(struct unpack_trees_options *o,
 220                              enum unpack_trees_error_types e,
 221                              const char *path)
 222 {
 223         if (!o->show_all_errors)
 224                 return error(ERRORMSG(o, e), super_prefixed(path));
 225
 226         /*
 227          * Otherwise, insert in a list for future display by
 228          * display_error_msgs()
 229          */
 230         string_list_append(&o->unpack_rejects[e], path);
 231         return -1;
 232 }
 233
 234 /*
 235  * display all the error messages stored in a nice way
 236  */
 237 static void display_error_msgs(struct unpack_trees_options *o)
 238 {
 239         int e, i;
 240         int something_displayed = 0;
 241         for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
 242                 struct string_list *rejects = &o->unpack_rejects[e];
 243                 if (rejects->nr > 0) {
 244                         struct strbuf path = STRBUF_INIT;
 245                         something_displayed = 1;
 246                         for (i = 0; i < rejects->nr; i++)
 247                                 strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
 248                         error(ERRORMSG(o, e), super_prefixed(path.buf));
 249                         strbuf_release(&path);
 250                 }
 251                 string_list_clear(rejects, 0);
 252         }
 253         if (something_displayed)
 254                 fprintf(stderr, _("Aborting\n"));
 255 }
 256
 257 static int check_submodule_move_head(const struct cache_entry *ce,
 258                                      const char *old_id,
 259                                      const char *new_id,
 260                                      struct unpack_trees_options *o)
 261 {
 262         unsigned flags = SUBMODULE_MOVE_HEAD_DRY_RUN;
 263         const struct submodule *sub = submodule_from_ce(ce);
 264
 265         if (!sub)
 266                 return 0;
 267
 268         if (o->reset)
 269                 flags |= SUBMODULE_MOVE_HEAD_FORCE;
 270
 271         if (submodule_move_head(ce->name, old_id, new_id, flags))
 272                 return o->gently ? -1 :
 273                                    add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
 274         return 0;
 275 }
 276
 277 /*
 278  * Preform the loading of the repository's gitmodules file.  This function is
 279  * used by 'check_update()' to perform loading of the gitmodules file in two
 280  * differnt situations:
 281  * (1) before removing entries from the working tree if the gitmodules file has
 282  *     been marked for removal.  This situation is specified by 'state' == NULL.
 283  * (2) before checking out entries to the working tree if the gitmodules file
 284  *     has been marked for update.  This situation is specified by 'state' != NULL.
 285  */
 286 static void load_gitmodules_file(struct index_state *index,
 287                                  struct checkout *state)
 288 {
 289         int pos = index_name_pos(index, GITMODULES_FILE, strlen(GITMODULES_FILE));
 290
 291         if (pos >= 0) {
 292                 struct cache_entry *ce = index->cache[pos];
 293                 if (!state && ce->ce_flags & CE_WT_REMOVE) {
 294                         repo_read_gitmodules(the_repository);
 295                 } else if (state && (ce->ce_flags & CE_UPDATE)) {
 296                         submodule_free(the_repository);
 297                         checkout_entry(ce, state, NULL);
 298                         repo_read_gitmodules(the_repository);
 299                 }
 300         }
 301 }
 302
 303 /*
 304  * Unlink the last component and schedule the leading directories for
 305  * removal, such that empty directories get removed.
 306  */
 307 static void unlink_entry(const struct cache_entry *ce)
 308 {
 309         const struct submodule *sub = submodule_from_ce(ce);
 310         if (sub) {
 311                 /* state.force is set at the caller. */
 312                 submodule_move_head(ce->name, "HEAD", NULL,
 313                                     SUBMODULE_MOVE_HEAD_FORCE);
 314         }
 315         if (!check_leading_path(ce->name, ce_namelen(ce)))
 316                 return;
 317         if (remove_or_warn(ce->ce_mode, ce->name))
 318                 return;
 319         schedule_dir_for_removal(ce->name, ce_namelen(ce));
 320 }
 321
 322 static struct progress *get_progress(struct unpack_trees_options *o)
 323 {
 324         unsigned cnt = 0, total = 0;
 325         struct index_state *index = &o->result;
 326
 327         if (!o->update || !o->verbose_update)
 328                 return NULL;
 329
 330         for (; cnt < index->cache_nr; cnt++) {
 331                 const struct cache_entry *ce = index->cache[cnt];
 332                 if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
 333                         total++;
 334         }
 335
 336         return start_delayed_progress(_("Checking out files"), total);
 337 }
 338
 339 static int check_updates(struct unpack_trees_options *o)
 340 {
 341         unsigned cnt = 0;
 342         int errs = 0;
 343         struct progress *progress = NULL;
 344         struct index_state *index = &o->result;
 345         struct checkout state = CHECKOUT_INIT;
 346         int i;
 347
 348         state.force = 1;
 349         state.quiet = 1;
 350         state.refresh_cache = 1;
 351         state.istate = index;
 352
 353         progress = get_progress(o);
 354
 355         if (o->update)
 356                 git_attr_set_direction(GIT_ATTR_CHECKOUT);
 357
 358         if (should_update_submodules() && o->update && !o->dry_run)
 359                 load_gitmodules_file(index, NULL);
 360
 361         for (i = 0; i < index->cache_nr; i++) {
 362                 const struct cache_entry *ce = index->cache[i];
 363
 364                 if (ce->ce_flags & CE_WT_REMOVE) {
 365                         display_progress(progress, ++cnt);
 366                         if (o->update && !o->dry_run)
 367                                 unlink_entry(ce);
 368                 }
 369         }
 370         remove_marked_cache_entries(index);
 371         remove_scheduled_dirs();
 372
 373         if (should_update_submodules() && o->update && !o->dry_run)
 374                 load_gitmodules_file(index, &state);
 375
 376         enable_delayed_checkout(&state);
 377         if (repository_format_partial_clone && o->update && !o->dry_run) {
 378                 /*
 379                  * Prefetch the objects that are to be checked out in the loop
 380                  * below.
 381                  */
 382                 struct oid_array to_fetch = OID_ARRAY_INIT;
 383                 int fetch_if_missing_store = fetch_if_missing;
 384                 fetch_if_missing = 0;
 385                 for (i = 0; i < index->cache_nr; i++) {
 386                         struct cache_entry *ce = index->cache[i];
 387                         if ((ce->ce_flags & CE_UPDATE) &&
 388                             !S_ISGITLINK(ce->ce_mode)) {
 389                                 if (!has_object_file(&ce->oid))
 390                                         oid_array_append(&to_fetch, &ce->oid);
 391                         }
 392                 }
 393                 if (to_fetch.nr)
 394                         fetch_objects(repository_format_partial_clone,
 395                                       to_fetch.oid, to_fetch.nr);
 396                 fetch_if_missing = fetch_if_missing_store;
 397                 oid_array_clear(&to_fetch);
 398         }
 399         for (i = 0; i < index->cache_nr; i++) {
 400                 struct cache_entry *ce = index->cache[i];
 401
 402                 if (ce->ce_flags & CE_UPDATE) {
 403                         if (ce->ce_flags & CE_WT_REMOVE)
 404                                 BUG("both update and delete flags are set on %s",
 405                                     ce->name);
 406                         display_progress(progress, ++cnt);
 407                         ce->ce_flags &= ~CE_UPDATE;
 408                         if (o->update && !o->dry_run) {
 409                                 errs |= checkout_entry(ce, &state, NULL);
 410                         }
 411                 }
 412         }
 413         stop_progress(&progress);
 414         errs |= finish_delayed_checkout(&state);
 415         if (o->update)
 416                 git_attr_set_direction(GIT_ATTR_CHECKIN);
 417         return errs != 0;
 418 }
 419
 420 static int verify_uptodate_sparse(const struct cache_entry *ce,
 421                                   struct unpack_trees_options *o);
 422 static int verify_absent_sparse(const struct cache_entry *ce,
 423                                 enum unpack_trees_error_types,
 424                                 struct unpack_trees_options *o);
 425
 426 static int apply_sparse_checkout(struct index_state *istate,
 427                                  struct cache_entry *ce,
 428                                  struct unpack_trees_options *o)
 429 {
 430         int was_skip_worktree = ce_skip_worktree(ce);
 431
 432         if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
 433                 ce->ce_flags |= CE_SKIP_WORKTREE;
 434         else
 435                 ce->ce_flags &= ~CE_SKIP_WORKTREE;
 436         if (was_skip_worktree != ce_skip_worktree(ce)) {
 437                 ce->ce_flags |= CE_UPDATE_IN_BASE;
 438                 mark_fsmonitor_invalid(istate, ce);
 439                 istate->cache_changed |= CE_ENTRY_CHANGED;
 440         }
 441
 442         /*
 443          * if (!was_skip_worktree && !ce_skip_worktree()) {
 444          *      This is perfectly normal. Move on;
 445          * }
 446          */
 447
 448         /*
 449          * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
 450          * area as a result of ce_skip_worktree() shortcuts in
 451          * verify_absent() and verify_uptodate().
 452          * Make sure they don't modify worktree if they are already
 453          * outside checkout area
 454          */
 455         if (was_skip_worktree && ce_skip_worktree(ce)) {
 456                 ce->ce_flags &= ~CE_UPDATE;
 457
 458                 /*
 459                  * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
 460                  * on to get that file removed from both index and worktree.
 461                  * If that file is already outside worktree area, don't
 462                  * bother remove it.
 463                  */
 464                 if (ce->ce_flags & CE_REMOVE)
 465                         ce->ce_flags &= ~CE_WT_REMOVE;
 466         }
 467
 468         if (!was_skip_worktree && ce_skip_worktree(ce)) {
 469                 /*
 470                  * If CE_UPDATE is set, verify_uptodate() must be called already
 471                  * also stat info may have lost after merged_entry() so calling
 472                  * verify_uptodate() again may fail
 473                  */
 474                 if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
 475                         return -1;
 476                 ce->ce_flags |= CE_WT_REMOVE;
 477                 ce->ce_flags &= ~CE_UPDATE;
 478         }
 479         if (was_skip_worktree && !ce_skip_worktree(ce)) {
 480                 if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
 481                         return -1;
 482                 ce->ce_flags |= CE_UPDATE;
 483         }
 484         return 0;
 485 }
 486
 487 static inline int call_unpack_fn(const struct cache_entry * const *src,
 488                                  struct unpack_trees_options *o)
 489 {
 490         int ret = o->fn(src, o);
 491         if (ret > 0)
 492                 ret = 0;
 493         return ret;
 494 }
 495
 496 static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
 497 {
 498         ce->ce_flags |= CE_UNPACKED;
 499
 500         if (o->cache_bottom < o->src_index->cache_nr &&
 501             o->src_index->cache[o->cache_bottom] == ce) {
 502                 int bottom = o->cache_bottom;
 503                 while (bottom < o->src_index->cache_nr &&
 504                        o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
 505                         bottom++;
 506                 o->cache_bottom = bottom;
 507         }
 508 }
 509
 510 static void mark_all_ce_unused(struct index_state *index)
 511 {
 512         int i;
 513         for (i = 0; i < index->cache_nr; i++)
 514                 index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
 515 }
 516
 517 static int locate_in_src_index(const struct cache_entry *ce,
 518                                struct unpack_trees_options *o)
 519 {
 520         struct index_state *index = o->src_index;
 521         int len = ce_namelen(ce);
 522         int pos = index_name_pos(index, ce->name, len);
 523         if (pos < 0)
 524                 pos = -1 - pos;
 525         return pos;
 526 }
 527
 528 /*
 529  * We call unpack_index_entry() with an unmerged cache entry
 530  * only in diff-index, and it wants a single callback.  Skip
 531  * the other unmerged entry with the same name.
 532  */
 533 static void mark_ce_used_same_name(struct cache_entry *ce,
 534                                    struct unpack_trees_options *o)
 535 {
 536         struct index_state *index = o->src_index;
 537         int len = ce_namelen(ce);
 538         int pos;
 539
 540         for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
 541                 struct cache_entry *next = index->cache[pos];
 542                 if (len != ce_namelen(next) ||
 543                     memcmp(ce->name, next->name, len))
 544                         break;
 545                 mark_ce_used(next, o);
 546         }
 547 }
 548
 549 static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
 550 {
 551         const struct index_state *index = o->src_index;
 552         int pos = o->cache_bottom;
 553
 554         while (pos < index->cache_nr) {
 555                 struct cache_entry *ce = index->cache[pos];
 556                 if (!(ce->ce_flags & CE_UNPACKED))
 557                         return ce;
 558                 pos++;
 559         }
 560         return NULL;
 561 }
 562
 563 static void add_same_unmerged(const struct cache_entry *ce,
 564                               struct unpack_trees_options *o)
 565 {
 566         struct index_state *index = o->src_index;
 567         int len = ce_namelen(ce);
 568         int pos = index_name_pos(index, ce->name, len);
 569
 570         if (0 <= pos)
 571                 die("programming error in a caller of mark_ce_used_same_name");
 572         for (pos = -pos - 1; pos < index->cache_nr; pos++) {
 573                 struct cache_entry *next = index->cache[pos];
 574                 if (len != ce_namelen(next) ||
 575                     memcmp(ce->name, next->name, len))
 576                         break;
 577                 add_entry(o, next, 0, 0);
 578                 mark_ce_used(next, o);
 579         }
 580 }
 581
 582 static int unpack_index_entry(struct cache_entry *ce,
 583                               struct unpack_trees_options *o)
 584 {
 585         const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 586         int ret;
 587
 588         src[0] = ce;
 589
 590         mark_ce_used(ce, o);
 591         if (ce_stage(ce)) {
 592                 if (o->skip_unmerged) {
 593                         add_entry(o, ce, 0, 0);
 594                         return 0;
 595                 }
 596         }
 597         ret = call_unpack_fn(src, o);
 598         if (ce_stage(ce))
 599                 mark_ce_used_same_name(ce, o);
 600         return ret;
 601 }
 602
 603 static int find_cache_pos(struct traverse_info *, const struct name_entry *);
 604
 605 static void restore_cache_bottom(struct traverse_info *info, int bottom)
 606 {
 607         struct unpack_trees_options *o = info->data;
 608
 609         if (o->diff_index_cached)
 610                 return;
 611         o->cache_bottom = bottom;
 612 }
 613
 614 static int switch_cache_bottom(struct traverse_info *info)
 615 {
 616         struct unpack_trees_options *o = info->data;
 617         int ret, pos;
 618
 619         if (o->diff_index_cached)
 620                 return 0;
 621         ret = o->cache_bottom;
 622         pos = find_cache_pos(info->prev, &info->name);
 623
 624         if (pos < -1)
 625                 o->cache_bottom = -2 - pos;
 626         else if (pos < 0)
 627                 o->cache_bottom = o->src_index->cache_nr;
 628         return ret;
 629 }
 630
 631 static inline int are_same_oid(struct name_entry *name_j, struct name_entry *name_k)
 632 {
 633         return name_j->oid && name_k->oid && !oidcmp(name_j->oid, name_k->oid);
 634 }
 635
 636 static int traverse_trees_recursive(int n, unsigned long dirmask,
 637                                     unsigned long df_conflicts,
 638                                     struct name_entry *names,
 639                                     struct traverse_info *info)
 640 {
 641         int i, ret, bottom;
 642         int nr_buf = 0;
 643         struct tree_desc t[MAX_UNPACK_TREES];
 644         void *buf[MAX_UNPACK_TREES];
 645         struct traverse_info newinfo;
 646         struct name_entry *p;
 647
 648         p = names;
 649         while (!p->mode)
 650                 p++;
 651
 652         newinfo = *info;
 653         newinfo.prev = info;
 654         newinfo.pathspec = info->pathspec;
 655         newinfo.name = *p;
 656         newinfo.pathlen += tree_entry_len(p) + 1;
 657         newinfo.df_conflicts |= df_conflicts;
 658
 659         /*
 660          * Fetch the tree from the ODB for each peer directory in the
 661          * n commits.
 662          *
 663          * For 2- and 3-way traversals, we try to avoid hitting the
 664          * ODB twice for the same OID.  This should yield a nice speed
 665          * up in checkouts and merges when the commits are similar.
 666          *
 667          * We don't bother doing the full O(n^2) search for larger n,
 668          * because wider traversals don't happen that often and we
 669          * avoid the search setup.
 670          *
 671          * When 2 peer OIDs are the same, we just copy the tree
 672          * descriptor data.  This implicitly borrows the buffer
 673          * data from the earlier cell.
 674          */
 675         for (i = 0; i < n; i++, dirmask >>= 1) {
 676                 if (i > 0 && are_same_oid(&names[i], &names[i - 1]))
 677                         t[i] = t[i - 1];
 678                 else if (i > 1 && are_same_oid(&names[i], &names[i - 2]))
 679                         t[i] = t[i - 2];
 680                 else {
 681                         const struct object_id *oid = NULL;
 682                         if (dirmask & 1)
 683                                 oid = names[i].oid;
 684                         buf[nr_buf++] = fill_tree_descriptor(t + i, oid);
 685                 }
 686         }
 687
 688         bottom = switch_cache_bottom(&newinfo);
 689         ret = traverse_trees(n, t, &newinfo);
 690         restore_cache_bottom(&newinfo, bottom);
 691
 692         for (i = 0; i < nr_buf; i++)
 693                 free(buf[i]);
 694
 695         return ret;
 696 }
 697
 698 /*
 699  * Compare the traverse-path to the cache entry without actually
 700  * having to generate the textual representation of the traverse
 701  * path.
 702  *
 703  * NOTE! This *only* compares up to the size of the traverse path
 704  * itself - the caller needs to do the final check for the cache
 705  * entry having more data at the end!
 706  */
 707 static int do_compare_entry_piecewise(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 708 {
 709         int len, pathlen, ce_len;
 710         const char *ce_name;
 711
 712         if (info->prev) {
 713                 int cmp = do_compare_entry_piecewise(ce, info->prev,
 714                                                      &info->name);
 715                 if (cmp)
 716                         return cmp;
 717         }
 718         pathlen = info->pathlen;
 719         ce_len = ce_namelen(ce);
 720
 721         /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 722         if (ce_len < pathlen)
 723                 return -1;
 724
 725         ce_len -= pathlen;
 726         ce_name = ce->name + pathlen;
 727
 728         len = tree_entry_len(n);
 729         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 730 }
 731
 732 static int do_compare_entry(const struct cache_entry *ce,
 733                             const struct traverse_info *info,
 734                             const struct name_entry *n)
 735 {
 736         int len, pathlen, ce_len;
 737         const char *ce_name;
 738         int cmp;
 739
 740         /*
 741          * If we have not precomputed the traverse path, it is quicker
 742          * to avoid doing so.  But if we have precomputed it,
 743          * it is quicker to use the precomputed version.
 744          */
 745         if (!info->traverse_path)
 746                 return do_compare_entry_piecewise(ce, info, n);
 747
 748         cmp = strncmp(ce->name, info->traverse_path, info->pathlen);
 749         if (cmp)
 750                 return cmp;
 751
 752         pathlen = info->pathlen;
 753         ce_len = ce_namelen(ce);
 754
 755         if (ce_len < pathlen)
 756                 return -1;
 757
 758         ce_len -= pathlen;
 759         ce_name = ce->name + pathlen;
 760
 761         len = tree_entry_len(n);
 762         return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 763 }
 764
 765 static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 766 {
 767         int cmp = do_compare_entry(ce, info, n);
 768         if (cmp)
 769                 return cmp;
 770
 771         /*
 772          * Even if the beginning compared identically, the ce should
 773          * compare as bigger than a directory leading up to it!
 774          */
 775         return ce_namelen(ce) > traverse_path_len(info, n);
 776 }
 777
 778 static int ce_in_traverse_path(const struct cache_entry *ce,
 779                                const struct traverse_info *info)
 780 {
 781         if (!info->prev)
 782                 return 1;
 783         if (do_compare_entry(ce, info->prev, &info->name))
 784                 return 0;
 785         /*
 786          * If ce (blob) is the same name as the path (which is a tree
 787          * we will be descending into), it won't be inside it.
 788          */
 789         return (info->pathlen < ce_namelen(ce));
 790 }
 791
 792 static struct cache_entry *create_ce_entry(const struct traverse_info *info,
 793         const struct name_entry *n,
 794         int stage,
 795         struct index_state *istate,
 796         int is_transient)
 797 {
 798         int len = traverse_path_len(info, n);
 799         struct cache_entry *ce =
 800                 is_transient ?
 801                 make_empty_transient_cache_entry(len) :
 802                 make_empty_cache_entry(istate, len);
 803
 804         ce->ce_mode = create_ce_mode(n->mode);
 805         ce->ce_flags = create_ce_flags(stage);
 806         ce->ce_namelen = len;
 807         oidcpy(&ce->oid, n->oid);
 808         make_traverse_path(ce->name, info, n);
 809
 810         return ce;
 811 }
 812
 813 static int unpack_nondirectories(int n, unsigned long mask,
 814                                  unsigned long dirmask,
 815                                  struct cache_entry **src,
 816                                  const struct name_entry *names,
 817                                  const struct traverse_info *info)
 818 {
 819         int i;
 820         struct unpack_trees_options *o = info->data;
 821         unsigned long conflicts = info->df_conflicts | dirmask;
 822
 823         /* Do we have *only* directories? Nothing to do */
 824         if (mask == dirmask && !src[0])
 825                 return 0;
 826
 827         /*
 828          * Ok, we've filled in up to any potential index entry in src[0],
 829          * now do the rest.
 830          */
 831         for (i = 0; i < n; i++) {
 832                 int stage;
 833                 unsigned int bit = 1ul << i;
 834                 if (conflicts & bit) {
 835                         src[i + o->merge] = o->df_conflict_entry;
 836                         continue;
 837                 }
 838                 if (!(mask & bit))
 839                         continue;
 840                 if (!o->merge)
 841                         stage = 0;
 842                 else if (i + 1 < o->head_idx)
 843                         stage = 1;
 844                 else if (i + 1 > o->head_idx)
 845                         stage = 3;
 846                 else
 847                         stage = 2;
 848
 849                 /*
 850                  * If the merge bit is set, then the cache entries are
 851                  * discarded in the following block.  In this case,
 852                  * construct "transient" cache_entries, as they are
 853                  * not stored in the index.  otherwise construct the
 854                  * cache entry from the index aware logic.
 855                  */
 856                 src[i + o->merge] = create_ce_entry(info, names + i, stage, &o->result, o->merge);
 857         }
 858
 859         if (o->merge) {
 860                 int rc = call_unpack_fn((const struct cache_entry * const *)src,
 861                                         o);
 862                 for (i = 0; i < n; i++) {
 863                         struct cache_entry *ce = src[i + o->merge];
 864                         if (ce != o->df_conflict_entry)
 865                                 discard_cache_entry(ce);
 866                 }
 867                 return rc;
 868         }
 869
 870         for (i = 0; i < n; i++)
 871                 if (src[i] && src[i] != o->df_conflict_entry)
 872                         if (do_add_entry(o, src[i], 0, 0))
 873                                 return -1;
 874
 875         return 0;
 876 }
 877
 878 static int unpack_failed(struct unpack_trees_options *o, const char *message)
 879 {
 880         discard_index(&o->result);
 881         if (!o->gently && !o->exiting_early) {
 882                 if (message)
 883                         return error("%s", message);
 884                 return -1;
 885         }
 886         return -1;
 887 }
 888
 889 /*
 890  * The tree traversal is looking at name p.  If we have a matching entry,
 891  * return it.  If name p is a directory in the index, do not return
 892  * anything, as we will want to match it when the traversal descends into
 893  * the directory.
 894  */
 895 static int find_cache_pos(struct traverse_info *info,
 896                           const struct name_entry *p)
 897 {
 898         int pos;
 899         struct unpack_trees_options *o = info->data;
 900         struct index_state *index = o->src_index;
 901         int pfxlen = info->pathlen;
 902         int p_len = tree_entry_len(p);
 903
 904         for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
 905                 const struct cache_entry *ce = index->cache[pos];
 906                 const char *ce_name, *ce_slash;
 907                 int cmp, ce_len;
 908
 909                 if (ce->ce_flags & CE_UNPACKED) {
 910                         /*
 911                          * cache_bottom entry is already unpacked, so
 912                          * we can never match it; don't check it
 913                          * again.
 914                          */
 915                         if (pos == o->cache_bottom)
 916                                 ++o->cache_bottom;
 917                         continue;
 918                 }
 919                 if (!ce_in_traverse_path(ce, info)) {
 920                         /*
 921                          * Check if we can skip future cache checks
 922                          * (because we're already past all possible
 923                          * entries in the traverse path).
 924                          */
 925                         if (info->traverse_path) {
 926                                 if (strncmp(ce->name, info->traverse_path,
 927                                             info->pathlen) > 0)
 928                                         break;
 929                         }
 930                         continue;
 931                 }
 932                 ce_name = ce->name + pfxlen;
 933                 ce_slash = strchr(ce_name, '/');
 934                 if (ce_slash)
 935                         ce_len = ce_slash - ce_name;
 936                 else
 937                         ce_len = ce_namelen(ce) - pfxlen;
 938                 cmp = name_compare(p->path, p_len, ce_name, ce_len);
 939                 /*
 940                  * Exact match; if we have a directory we need to
 941                  * delay returning it.
 942                  */
 943                 if (!cmp)
 944                         return ce_slash ? -2 - pos : pos;
 945                 if (0 < cmp)
 946                         continue; /* keep looking */
 947                 /*
 948                  * ce_name sorts after p->path; could it be that we
 949                  * have files under p->path directory in the index?
 950                  * E.g.  ce_name == "t-i", and p->path == "t"; we may
 951                  * have "t/a" in the index.
 952                  */
 953                 if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
 954                     ce_name[p_len] < '/')
 955                         continue; /* keep looking */
 956                 break;
 957         }
 958         return -1;
 959 }
 960
 961 static struct cache_entry *find_cache_entry(struct traverse_info *info,
 962                                             const struct name_entry *p)
 963 {
 964         int pos = find_cache_pos(info, p);
 965         struct unpack_trees_options *o = info->data;
 966
 967         if (0 <= pos)
 968                 return o->src_index->cache[pos];
 969         else
 970                 return NULL;
 971 }
 972
 973 static void debug_path(struct traverse_info *info)
 974 {
 975         if (info->prev) {
 976                 debug_path(info->prev);
 977                 if (*info->prev->name.path)
 978                         putchar('/');
 979         }
 980         printf("%s", info->name.path);
 981 }
 982
 983 static void debug_name_entry(int i, struct name_entry *n)
 984 {
 985         printf("ent#%d %06o %s\n", i,
 986                n->path ? n->mode : 0,
 987                n->path ? n->path : "(missing)");
 988 }
 989
 990 static void debug_unpack_callback(int n,
 991                                   unsigned long mask,
 992                                   unsigned long dirmask,
 993                                   struct name_entry *names,
 994                                   struct traverse_info *info)
 995 {
 996         int i;
 997         printf("* unpack mask %lu, dirmask %lu, cnt %d ",
 998                mask, dirmask, n);
 999         debug_path(info);
1000         putchar('\n');
1001         for (i = 0; i < n; i++)
1002                 debug_name_entry(i, names + i);
1003 }
1004
1005 static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
1006 {
1007         struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
1008         struct unpack_trees_options *o = info->data;
1009         const struct name_entry *p = names;
1010
1011         /* Find first entry with a real name (we could use "mask" too) */
1012         while (!p->mode)
1013                 p++;
1014
1015         if (o->debug_unpack)
1016                 debug_unpack_callback(n, mask, dirmask, names, info);
1017
1018         /* Are we supposed to look at the index too? */
1019         if (o->merge) {
1020                 while (1) {
1021                         int cmp;
1022                         struct cache_entry *ce;
1023
1024                         if (o->diff_index_cached)
1025                                 ce = next_cache_entry(o);
1026                         else
1027                                 ce = find_cache_entry(info, p);
1028
1029                         if (!ce)
1030                                 break;
1031                         cmp = compare_entry(ce, info, p);
1032                         if (cmp < 0) {
1033                                 if (unpack_index_entry(ce, o) < 0)
1034                                         return unpack_failed(o, NULL);
1035                                 continue;
1036                         }
1037                         if (!cmp) {
1038                                 if (ce_stage(ce)) {
1039                                         /*
1040                                          * If we skip unmerged index
1041                                          * entries, we'll skip this
1042                                          * entry *and* the tree
1043                                          * entries associated with it!
1044                                          */
1045                                         if (o->skip_unmerged) {
1046                                                 add_same_unmerged(ce, o);
1047                                                 return mask;
1048                                         }
1049                                 }
1050                                 src[0] = ce;
1051                         }
1052                         break;
1053                 }
1054         }
1055
1056         if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
1057                 return -1;
1058
1059         if (o->merge && src[0]) {
1060                 if (ce_stage(src[0]))
1061                         mark_ce_used_same_name(src[0], o);
1062                 else
1063                         mark_ce_used(src[0], o);
1064         }
1065
1066         /* Now handle any directories.. */
1067         if (dirmask) {
1068                 /* special case: "diff-index --cached" looking at a tree */
1069                 if (o->diff_index_cached &&
1070                     n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
1071                         int matches;
1072                         matches = cache_tree_matches_traversal(o->src_index->cache_tree,
1073                                                                names, info);
1074                         /*
1075                          * Everything under the name matches; skip the
1076                          * entire hierarchy.  diff_index_cached codepath
1077                          * special cases D/F conflicts in such a way that
1078                          * it does not do any look-ahead, so this is safe.
1079                          */
1080                         if (matches) {
1081                                 o->cache_bottom += matches;
1082                                 return mask;
1083                         }
1084                 }
1085
1086                 if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
1087                                              names, info) < 0)
1088                         return -1;
1089                 return mask;
1090         }
1091
1092         return mask;
1093 }
1094
1095 static int clear_ce_flags_1(struct index_state *istate,
1096                             struct cache_entry **cache, int nr,
1097                             struct strbuf *prefix,
1098                             int select_mask, int clear_mask,
1099                             struct exclude_list *el, int defval);
1100
1101 /* Whole directory matching */
1102 static int clear_ce_flags_dir(struct index_state *istate,
1103                               struct cache_entry **cache, int nr,
1104                               struct strbuf *prefix,
1105                               char *basename,
1106                               int select_mask, int clear_mask,
1107                               struct exclude_list *el, int defval)
1108 {
1109         struct cache_entry **cache_end;
1110         int dtype = DT_DIR;
1111         int ret = is_excluded_from_list(prefix->buf, prefix->len,
1112                                         basename, &dtype, el, istate);
1113         int rc;
1114
1115         strbuf_addch(prefix, '/');
1116
1117         /* If undecided, use matching result of parent dir in defval */
1118         if (ret < 0)
1119                 ret = defval;
1120
1121         for (cache_end = cache; cache_end != cache + nr; cache_end++) {
1122                 struct cache_entry *ce = *cache_end;
1123                 if (strncmp(ce->name, prefix->buf, prefix->len))
1124                         break;
1125         }
1126
1127         /*
1128          * TODO: check el, if there are no patterns that may conflict
1129          * with ret (iow, we know in advance the incl/excl
1130          * decision for the entire directory), clear flag here without
1131          * calling clear_ce_flags_1(). That function will call
1132          * the expensive is_excluded_from_list() on every entry.
1133          */
1134         rc = clear_ce_flags_1(istate, cache, cache_end - cache,
1135                               prefix,
1136                               select_mask, clear_mask,
1137                               el, ret);
1138         strbuf_setlen(prefix, prefix->len - 1);
1139         return rc;
1140 }
1141
1142 /*
1143  * Traverse the index, find every entry that matches according to
1144  * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
1145  * number of traversed entries.
1146  *
1147  * If select_mask is non-zero, only entries whose ce_flags has on of
1148  * those bits enabled are traversed.
1149  *
1150  * cache        : pointer to an index entry
1151  * prefix_len   : an offset to its path
1152  *
1153  * The current path ("prefix") including the trailing '/' is
1154  *   cache[0]->name[0..(prefix_len-1)]
1155  * Top level path has prefix_len zero.
1156  */
1157 static int clear_ce_flags_1(struct index_state *istate,
1158                             struct cache_entry **cache, int nr,
1159                             struct strbuf *prefix,
1160                             int select_mask, int clear_mask,
1161                             struct exclude_list *el, int defval)
1162 {
1163         struct cache_entry **cache_end = cache + nr;
1164
1165         /*
1166          * Process all entries that have the given prefix and meet
1167          * select_mask condition
1168          */
1169         while(cache != cache_end) {
1170                 struct cache_entry *ce = *cache;
1171                 const char *name, *slash;
1172                 int len, dtype, ret;
1173
1174                 if (select_mask && !(ce->ce_flags & select_mask)) {
1175                         cache++;
1176                         continue;
1177                 }
1178
1179                 if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
1180                         break;
1181
1182                 name = ce->name + prefix->len;
1183                 slash = strchr(name, '/');
1184
1185                 /* If it's a directory, try whole directory match first */
1186                 if (slash) {
1187                         int processed;
1188
1189                         len = slash - name;
1190                         strbuf_add(prefix, name, len);
1191
1192                         processed = clear_ce_flags_dir(istate, cache, cache_end - cache,
1193                                                        prefix,
1194                                                        prefix->buf + prefix->len - len,
1195                                                        select_mask, clear_mask,
1196                                                        el, defval);
1197
1198                         /* clear_c_f_dir eats a whole dir already? */
1199                         if (processed) {
1200                                 cache += processed;
1201                                 strbuf_setlen(prefix, prefix->len - len);
1202                                 continue;
1203                         }
1204
1205                         strbuf_addch(prefix, '/');
1206                         cache += clear_ce_flags_1(istate, cache, cache_end - cache,
1207                                                   prefix,
1208                                                   select_mask, clear_mask, el, defval);
1209                         strbuf_setlen(prefix, prefix->len - len - 1);
1210                         continue;
1211                 }
1212
1213                 /* Non-directory */
1214                 dtype = ce_to_dtype(ce);
1215                 ret = is_excluded_from_list(ce->name, ce_namelen(ce),
1216                                             name, &dtype, el, istate);
1217                 if (ret < 0)
1218                         ret = defval;
1219                 if (ret > 0)
1220                         ce->ce_flags &= ~clear_mask;
1221                 cache++;
1222         }
1223         return nr - (cache_end - cache);
1224 }
1225
1226 static int clear_ce_flags(struct index_state *istate,
1227                           int select_mask, int clear_mask,
1228                           struct exclude_list *el)
1229 {
1230         static struct strbuf prefix = STRBUF_INIT;
1231
1232         strbuf_reset(&prefix);
1233
1234         return clear_ce_flags_1(istate,
1235                                 istate->cache,
1236                                 istate->cache_nr,
1237                                 &prefix,
1238                                 select_mask, clear_mask,
1239                                 el, 0);
1240 }
1241
1242 /*
1243  * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
1244  */
1245 static void mark_new_skip_worktree(struct exclude_list *el,
1246                                    struct index_state *istate,
1247                                    int select_flag, int skip_wt_flag)
1248 {
1249         int i;
1250
1251         /*
1252          * 1. Pretend the narrowest worktree: only unmerged entries
1253          * are checked out
1254          */
1255         for (i = 0; i < istate->cache_nr; i++) {
1256                 struct cache_entry *ce = istate->cache[i];
1257
1258                 if (select_flag && !(ce->ce_flags & select_flag))
1259                         continue;
1260
1261                 if (!ce_stage(ce) && !(ce->ce_flags & CE_CONFLICTED))
1262                         ce->ce_flags |= skip_wt_flag;
1263                 else
1264                         ce->ce_flags &= ~skip_wt_flag;
1265         }
1266
1267         /*
1268          * 2. Widen worktree according to sparse-checkout file.
1269          * Matched entries will have skip_wt_flag cleared (i.e. "in")
1270          */
1271         clear_ce_flags(istate, select_flag, skip_wt_flag, el);
1272 }
1273
1274 static int verify_absent(const struct cache_entry *,
1275                          enum unpack_trees_error_types,
1276                          struct unpack_trees_options *);
1277 /*
1278  * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1279  * resulting index, -2 on failure to reflect the changes to the work tree.
1280  *
1281  * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1282  */
1283 int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1284 {
1285         int i, ret;
1286         static struct cache_entry *dfc;
1287         struct exclude_list el;
1288
1289         if (len > MAX_UNPACK_TREES)
1290                 die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1291
1292         memset(&el, 0, sizeof(el));
1293         if (!core_apply_sparse_checkout || !o->update)
1294                 o->skip_sparse_checkout = 1;
1295         if (!o->skip_sparse_checkout) {
1296                 char *sparse = git_pathdup("info/sparse-checkout");
1297                 if (add_excludes_from_file_to_list(sparse, "", 0, &el, NULL) < 0)
1298                         o->skip_sparse_checkout = 1;
1299                 else
1300                         o->el = &el;
1301                 free(sparse);
1302         }
1303
1304         memset(&o->result, 0, sizeof(o->result));
1305         o->result.initialized = 1;
1306         o->result.timestamp.sec = o->src_index->timestamp.sec;
1307         o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1308         o->result.version = o->src_index->version;
1309         if (!o->src_index->split_index) {
1310                 o->result.split_index = NULL;
1311         } else if (o->src_index == o->dst_index) {
1312                 /*
1313                  * o->dst_index (and thus o->src_index) will be discarded
1314                  * and overwritten with o->result at the end of this function,
1315                  * so just use src_index's split_index to avoid having to
1316                  * create a new one.
1317                  */
1318                 o->result.split_index = o->src_index->split_index;
1319                 o->result.split_index->refcount++;
1320         } else {
1321                 o->result.split_index = init_split_index(&o->result);
1322         }
1323         oidcpy(&o->result.oid, &o->src_index->oid);
1324         o->merge_size = len;
1325         mark_all_ce_unused(o->src_index);
1326
1327         /*
1328          * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1329          */
1330         if (!o->skip_sparse_checkout)
1331                 mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1332
1333         if (!dfc)
1334                 dfc = xcalloc(1, cache_entry_size(0));
1335         o->df_conflict_entry = dfc;
1336
1337         if (len) {
1338                 const char *prefix = o->prefix ? o->prefix : "";
1339                 struct traverse_info info;
1340
1341                 setup_traverse_info(&info, prefix);
1342                 info.fn = unpack_callback;
1343                 info.data = o;
1344                 info.show_all_errors = o->show_all_errors;
1345                 info.pathspec = o->pathspec;
1346
1347                 if (o->prefix) {
1348                         /*
1349                          * Unpack existing index entries that sort before the
1350                          * prefix the tree is spliced into.  Note that o->merge
1351                          * is always true in this case.
1352                          */
1353                         while (1) {
1354                                 struct cache_entry *ce = next_cache_entry(o);
1355                                 if (!ce)
1356                                         break;
1357                                 if (ce_in_traverse_path(ce, &info))
1358                                         break;
1359                                 if (unpack_index_entry(ce, o) < 0)
1360                                         goto return_failed;
1361                         }
1362                 }
1363
1364                 if (traverse_trees(len, t, &info) < 0)
1365                         goto return_failed;
1366         }
1367
1368         /* Any left-over entries in the index? */
1369         if (o->merge) {
1370                 while (1) {
1371                         struct cache_entry *ce = next_cache_entry(o);
1372                         if (!ce)
1373                                 break;
1374                         if (unpack_index_entry(ce, o) < 0)
1375                                 goto return_failed;
1376                 }
1377         }
1378         mark_all_ce_unused(o->src_index);
1379
1380         if (o->trivial_merges_only && o->nontrivial_merge) {
1381                 ret = unpack_failed(o, "Merge requires file-level merging");
1382                 goto done;
1383         }
1384
1385         if (!o->skip_sparse_checkout) {
1386                 int empty_worktree = 1;
1387
1388                 /*
1389                  * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1390                  * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1391                  * so apply_sparse_checkout() won't attempt to remove it from worktree
1392                  */
1393                 mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1394
1395                 ret = 0;
1396                 for (i = 0; i < o->result.cache_nr; i++) {
1397                         struct cache_entry *ce = o->result.cache[i];
1398
1399                         /*
1400                          * Entries marked with CE_ADDED in merged_entry() do not have
1401                          * verify_absent() check (the check is effectively disabled
1402                          * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1403                          *
1404                          * Do the real check now because we have had
1405                          * correct CE_NEW_SKIP_WORKTREE
1406                          */
1407                         if (ce->ce_flags & CE_ADDED &&
1408                             verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1409                                 if (!o->show_all_errors)
1410                                         goto return_failed;
1411                                 ret = -1;
1412                         }
1413
1414                         if (apply_sparse_checkout(&o->result, ce, o)) {
1415                                 if (!o->show_all_errors)
1416                                         goto return_failed;
1417                                 ret = -1;
1418                         }
1419                         if (!ce_skip_worktree(ce))
1420                                 empty_worktree = 0;
1421
1422                 }
1423                 if (ret < 0)
1424                         goto return_failed;
1425                 /*
1426                  * Sparse checkout is meant to narrow down checkout area
1427                  * but it does not make sense to narrow down to empty working
1428                  * tree. This is usually a mistake in sparse checkout rules.
1429                  * Do not allow users to do that.
1430                  */
1431                 if (o->result.cache_nr && empty_worktree) {
1432                         ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1433                         goto done;
1434                 }
1435         }
1436
1437         ret = check_updates(o) ? (-2) : 0;
1438         if (o->dst_index) {
1439                 if (!ret) {
1440                         if (!o->result.cache_tree)
1441                                 o->result.cache_tree = cache_tree();
1442                         if (!cache_tree_fully_valid(o->result.cache_tree))
1443                                 cache_tree_update(&o->result,
1444                                                   WRITE_TREE_SILENT |
1445                                                   WRITE_TREE_REPAIR);
1446                 }
1447                 move_index_extensions(&o->result, o->src_index);
1448                 discard_index(o->dst_index);
1449                 *o->dst_index = o->result;
1450         } else {
1451                 discard_index(&o->result);
1452         }
1453         o->src_index = NULL;
1454
1455 done:
1456         clear_exclude_list(&el);
1457         return ret;
1458
1459 return_failed:
1460         if (o->show_all_errors)
1461                 display_error_msgs(o);
1462         mark_all_ce_unused(o->src_index);
1463         ret = unpack_failed(o, NULL);
1464         if (o->exiting_early)
1465                 ret = 0;
1466         goto done;
1467 }
1468
1469 /* Here come the merge functions */
1470
1471 static int reject_merge(const struct cache_entry *ce,
1472                         struct unpack_trees_options *o)
1473 {
1474         return o->gently ? -1 :
1475                 add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1476 }
1477
1478 static int same(const struct cache_entry *a, const struct cache_entry *b)
1479 {
1480         if (!!a != !!b)
1481                 return 0;
1482         if (!a && !b)
1483                 return 1;
1484         if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1485                 return 0;
1486         return a->ce_mode == b->ce_mode &&
1487                !oidcmp(&a->oid, &b->oid);
1488 }
1489
1490
1491 /*
1492  * When a CE gets turned into an unmerged entry, we
1493  * want it to be up-to-date
1494  */
1495 static int verify_uptodate_1(const struct cache_entry *ce,
1496                              struct unpack_trees_options *o,
1497                              enum unpack_trees_error_types error_type)
1498 {
1499         struct stat st;
1500
1501         if (o->index_only)
1502                 return 0;
1503
1504         /*
1505          * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1506          * if this entry is truly up-to-date because this file may be
1507          * overwritten.
1508          */
1509         if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1510                 ; /* keep checking */
1511         else if (o->reset || ce_uptodate(ce))
1512                 return 0;
1513
1514         if (!lstat(ce->name, &st)) {
1515                 int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1516                 unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1517
1518                 if (submodule_from_ce(ce)) {
1519                         int r = check_submodule_move_head(ce,
1520                                 "HEAD", oid_to_hex(&ce->oid), o);
1521                         if (r)
1522                                 return o->gently ? -1 :
1523                                         add_rejected_path(o, error_type, ce->name);
1524                         return 0;
1525                 }
1526
1527                 if (!changed)
1528                         return 0;
1529                 /*
1530                  * Historic default policy was to allow submodule to be out
1531                  * of sync wrt the superproject index. If the submodule was
1532                  * not considered interesting above, we don't care here.
1533                  */
1534                 if (S_ISGITLINK(ce->ce_mode))
1535                         return 0;
1536
1537                 errno = 0;
1538         }
1539         if (errno == ENOENT)
1540                 return 0;
1541         return o->gently ? -1 :
1542                 add_rejected_path(o, error_type, ce->name);
1543 }
1544
1545 int verify_uptodate(const struct cache_entry *ce,
1546                     struct unpack_trees_options *o)
1547 {
1548         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1549                 return 0;
1550         return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1551 }
1552
1553 static int verify_uptodate_sparse(const struct cache_entry *ce,
1554                                   struct unpack_trees_options *o)
1555 {
1556         return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1557 }
1558
1559 /*
1560  * TODO: We should actually invalidate o->result, not src_index [1].
1561  * But since cache tree and untracked cache both are not copied to
1562  * o->result until unpacking is complete, we invalidate them on
1563  * src_index instead with the assumption that they will be copied to
1564  * dst_index at the end.
1565  *
1566  * [1] src_index->cache_tree is also used in unpack_callback() so if
1567  * we invalidate o->result, we need to update it to use
1568  * o->result.cache_tree as well.
1569  */
1570 static void invalidate_ce_path(const struct cache_entry *ce,
1571                                struct unpack_trees_options *o)
1572 {
1573         if (!ce)
1574                 return;
1575         cache_tree_invalidate_path(o->src_index, ce->name);
1576         untracked_cache_invalidate_path(o->src_index, ce->name, 1);
1577 }
1578
1579 /*
1580  * Check that checking out ce->sha1 in subdir ce->name is not
1581  * going to overwrite any working files.
1582  *
1583  * Currently, git does not checkout subprojects during a superproject
1584  * checkout, so it is not going to overwrite anything.
1585  */
1586 static int verify_clean_submodule(const char *old_sha1,
1587                                   const struct cache_entry *ce,
1588                                   enum unpack_trees_error_types error_type,
1589                                   struct unpack_trees_options *o)
1590 {
1591         if (!submodule_from_ce(ce))
1592                 return 0;
1593
1594         return check_submodule_move_head(ce, old_sha1,
1595                                          oid_to_hex(&ce->oid), o);
1596 }
1597
1598 static int verify_clean_subdirectory(const struct cache_entry *ce,
1599                                      enum unpack_trees_error_types error_type,
1600                                      struct unpack_trees_options *o)
1601 {
1602         /*
1603          * we are about to extract "ce->name"; we would not want to lose
1604          * anything in the existing directory there.
1605          */
1606         int namelen;
1607         int i;
1608         struct dir_struct d;
1609         char *pathbuf;
1610         int cnt = 0;
1611
1612         if (S_ISGITLINK(ce->ce_mode)) {
1613                 struct object_id oid;
1614                 int sub_head = resolve_gitlink_ref(ce->name, "HEAD", &oid);
1615                 /*
1616                  * If we are not going to update the submodule, then
1617                  * we don't care.
1618                  */
1619                 if (!sub_head && !oidcmp(&oid, &ce->oid))
1620                         return 0;
1621                 return verify_clean_submodule(sub_head ? NULL : oid_to_hex(&oid),
1622                                               ce, error_type, o);
1623         }
1624
1625         /*
1626          * First let's make sure we do not have a local modification
1627          * in that directory.
1628          */
1629         namelen = ce_namelen(ce);
1630         for (i = locate_in_src_index(ce, o);
1631              i < o->src_index->cache_nr;
1632              i++) {
1633                 struct cache_entry *ce2 = o->src_index->cache[i];
1634                 int len = ce_namelen(ce2);
1635                 if (len < namelen ||
1636                     strncmp(ce->name, ce2->name, namelen) ||
1637                     ce2->name[namelen] != '/')
1638                         break;
1639                 /*
1640                  * ce2->name is an entry in the subdirectory to be
1641                  * removed.
1642                  */
1643                 if (!ce_stage(ce2)) {
1644                         if (verify_uptodate(ce2, o))
1645                                 return -1;
1646                         add_entry(o, ce2, CE_REMOVE, 0);
1647                         mark_ce_used(ce2, o);
1648                 }
1649                 cnt++;
1650         }
1651
1652         /*
1653          * Then we need to make sure that we do not lose a locally
1654          * present file that is not ignored.
1655          */
1656         pathbuf = xstrfmt("%.*s/", namelen, ce->name);
1657
1658         memset(&d, 0, sizeof(d));
1659         if (o->dir)
1660                 d.exclude_per_dir = o->dir->exclude_per_dir;
1661         i = read_directory(&d, o->src_index, pathbuf, namelen+1, NULL);
1662         if (i)
1663                 return o->gently ? -1 :
1664                         add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1665         free(pathbuf);
1666         return cnt;
1667 }
1668
1669 /*
1670  * This gets called when there was no index entry for the tree entry 'dst',
1671  * but we found a file in the working tree that 'lstat()' said was fine,
1672  * and we're on a case-insensitive filesystem.
1673  *
1674  * See if we can find a case-insensitive match in the index that also
1675  * matches the stat information, and assume it's that other file!
1676  */
1677 static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1678 {
1679         const struct cache_entry *src;
1680
1681         src = index_file_exists(o->src_index, name, len, 1);
1682         return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1683 }
1684
1685 static int check_ok_to_remove(const char *name, int len, int dtype,
1686                               const struct cache_entry *ce, struct stat *st,
1687                               enum unpack_trees_error_types error_type,
1688                               struct unpack_trees_options *o)
1689 {
1690         const struct cache_entry *result;
1691
1692         /*
1693          * It may be that the 'lstat()' succeeded even though
1694          * target 'ce' was absent, because there is an old
1695          * entry that is different only in case..
1696          *
1697          * Ignore that lstat() if it matches.
1698          */
1699         if (ignore_case && icase_exists(o, name, len, st))
1700                 return 0;
1701
1702         if (o->dir &&
1703             is_excluded(o->dir, o->src_index, name, &dtype))
1704                 /*
1705                  * ce->name is explicitly excluded, so it is Ok to
1706                  * overwrite it.
1707                  */
1708                 return 0;
1709         if (S_ISDIR(st->st_mode)) {
1710                 /*
1711                  * We are checking out path "foo" and
1712                  * found "foo/." in the working tree.
1713                  * This is tricky -- if we have modified
1714                  * files that are in "foo/" we would lose
1715                  * them.
1716                  */
1717                 if (verify_clean_subdirectory(ce, error_type, o) < 0)
1718                         return -1;
1719                 return 0;
1720         }
1721
1722         /*
1723          * The previous round may already have decided to
1724          * delete this path, which is in a subdirectory that
1725          * is being replaced with a blob.
1726          */
1727         result = index_file_exists(&o->result, name, len, 0);
1728         if (result) {
1729                 if (result->ce_flags & CE_REMOVE)
1730                         return 0;
1731         }
1732
1733         return o->gently ? -1 :
1734                 add_rejected_path(o, error_type, name);
1735 }
1736
1737 /*
1738  * We do not want to remove or overwrite a working tree file that
1739  * is not tracked, unless it is ignored.
1740  */
1741 static int verify_absent_1(const struct cache_entry *ce,
1742                            enum unpack_trees_error_types error_type,
1743                            struct unpack_trees_options *o)
1744 {
1745         int len;
1746         struct stat st;
1747
1748         if (o->index_only || o->reset || !o->update)
1749                 return 0;
1750
1751         len = check_leading_path(ce->name, ce_namelen(ce));
1752         if (!len)
1753                 return 0;
1754         else if (len > 0) {
1755                 char *path;
1756                 int ret;
1757
1758                 path = xmemdupz(ce->name, len);
1759                 if (lstat(path, &st))
1760                         ret = error_errno("cannot stat '%s'", path);
1761                 else {
1762                         if (submodule_from_ce(ce))
1763                                 ret = check_submodule_move_head(ce,
1764                                                                 oid_to_hex(&ce->oid),
1765                                                                 NULL, o);
1766                         else
1767                                 ret = check_ok_to_remove(path, len, DT_UNKNOWN, NULL,
1768                                                          &st, error_type, o);
1769                 }
1770                 free(path);
1771                 return ret;
1772         } else if (lstat(ce->name, &st)) {
1773                 if (errno != ENOENT)
1774                         return error_errno("cannot stat '%s'", ce->name);
1775                 return 0;
1776         } else {
1777                 if (submodule_from_ce(ce))
1778                         return check_submodule_move_head(ce, oid_to_hex(&ce->oid),
1779                                                          NULL, o);
1780
1781                 return check_ok_to_remove(ce->name, ce_namelen(ce),
1782                                           ce_to_dtype(ce), ce, &st,
1783                                           error_type, o);
1784         }
1785 }
1786
1787 static int verify_absent(const struct cache_entry *ce,
1788                          enum unpack_trees_error_types error_type,
1789                          struct unpack_trees_options *o)
1790 {
1791         if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1792                 return 0;
1793         return verify_absent_1(ce, error_type, o);
1794 }
1795
1796 static int verify_absent_sparse(const struct cache_entry *ce,
1797                                 enum unpack_trees_error_types error_type,
1798                                 struct unpack_trees_options *o)
1799 {
1800         enum unpack_trees_error_types orphaned_error = error_type;
1801         if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1802                 orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1803
1804         return verify_absent_1(ce, orphaned_error, o);
1805 }
1806
1807 static int merged_entry(const struct cache_entry *ce,
1808                         const struct cache_entry *old,
1809                         struct unpack_trees_options *o)
1810 {
1811         int update = CE_UPDATE;
1812         struct cache_entry *merge = dup_cache_entry(ce, &o->result);
1813
1814         if (!old) {
1815                 /*
1816                  * New index entries. In sparse checkout, the following
1817                  * verify_absent() will be delayed until after
1818                  * traverse_trees() finishes in unpack_trees(), then:
1819                  *
1820                  *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1821                  *  - verify_absent() be called again, this time with
1822                  *    correct CE_NEW_SKIP_WORKTREE
1823                  *
1824                  * verify_absent() call here does nothing in sparse
1825                  * checkout (i.e. o->skip_sparse_checkout == 0)
1826                  */
1827                 update |= CE_ADDED;
1828                 merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1829
1830                 if (verify_absent(merge,
1831                                   ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1832                         discard_cache_entry(merge);
1833                         return -1;
1834                 }
1835                 invalidate_ce_path(merge, o);
1836
1837                 if (submodule_from_ce(ce)) {
1838                         int ret = check_submodule_move_head(ce, NULL,
1839                                                             oid_to_hex(&ce->oid),
1840                                                             o);
1841                         if (ret)
1842                                 return ret;
1843                 }
1844
1845         } else if (!(old->ce_flags & CE_CONFLICTED)) {
1846                 /*
1847                  * See if we can re-use the old CE directly?
1848                  * That way we get the uptodate stat info.
1849                  *
1850                  * This also removes the UPDATE flag on a match; otherwise
1851                  * we will end up overwriting local changes in the work tree.
1852                  */
1853                 if (same(old, merge)) {
1854                         copy_cache_entry(merge, old);
1855                         update = 0;
1856                 } else {
1857                         if (verify_uptodate(old, o)) {
1858                                 discard_cache_entry(merge);
1859                                 return -1;
1860                         }
1861                         /* Migrate old flags over */
1862                         update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1863                         invalidate_ce_path(old, o);
1864                 }
1865
1866                 if (submodule_from_ce(ce)) {
1867                         int ret = check_submodule_move_head(ce, oid_to_hex(&old->oid),
1868                                                             oid_to_hex(&ce->oid),
1869                                                             o);
1870                         if (ret)
1871                                 return ret;
1872                 }
1873         } else {
1874                 /*
1875                  * Previously unmerged entry left as an existence
1876                  * marker by read_index_unmerged();
1877                  */
1878                 invalidate_ce_path(old, o);
1879         }
1880
1881         if (do_add_entry(o, merge, update, CE_STAGEMASK) < 0)
1882                 return -1;
1883         return 1;
1884 }
1885
1886 static int deleted_entry(const struct cache_entry *ce,
1887                          const struct cache_entry *old,
1888                          struct unpack_trees_options *o)
1889 {
1890         /* Did it exist in the index? */
1891         if (!old) {
1892                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1893                         return -1;
1894                 return 0;
1895         }
1896         if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1897                 return -1;
1898         add_entry(o, ce, CE_REMOVE, 0);
1899         invalidate_ce_path(ce, o);
1900         return 1;
1901 }
1902
1903 static int keep_entry(const struct cache_entry *ce,
1904                       struct unpack_trees_options *o)
1905 {
1906         add_entry(o, ce, 0, 0);
1907         return 1;
1908 }
1909
1910 #if DBRT_DEBUG
1911 static void show_stage_entry(FILE *o,
1912                              const char *label, const struct cache_entry *ce)
1913 {
1914         if (!ce)
1915                 fprintf(o, "%s (missing)\n", label);
1916         else
1917                 fprintf(o, "%s%06o %s %d\t%s\n",
1918                         label,
1919                         ce->ce_mode,
1920                         oid_to_hex(&ce->oid),
1921                         ce_stage(ce),
1922                         ce->name);
1923 }
1924 #endif
1925
1926 int threeway_merge(const struct cache_entry * const *stages,
1927                    struct unpack_trees_options *o)
1928 {
1929         const struct cache_entry *index;
1930         const struct cache_entry *head;
1931         const struct cache_entry *remote = stages[o->head_idx + 1];
1932         int count;
1933         int head_match = 0;
1934         int remote_match = 0;
1935
1936         int df_conflict_head = 0;
1937         int df_conflict_remote = 0;
1938
1939         int any_anc_missing = 0;
1940         int no_anc_exists = 1;
1941         int i;
1942
1943         for (i = 1; i < o->head_idx; i++) {
1944                 if (!stages[i] || stages[i] == o->df_conflict_entry)
1945                         any_anc_missing = 1;
1946                 else
1947                         no_anc_exists = 0;
1948         }
1949
1950         index = stages[0];
1951         head = stages[o->head_idx];
1952
1953         if (head == o->df_conflict_entry) {
1954                 df_conflict_head = 1;
1955                 head = NULL;
1956         }
1957
1958         if (remote == o->df_conflict_entry) {
1959                 df_conflict_remote = 1;
1960                 remote = NULL;
1961         }
1962
1963         /*
1964          * First, if there's a #16 situation, note that to prevent #13
1965          * and #14.
1966          */
1967         if (!same(remote, head)) {
1968                 for (i = 1; i < o->head_idx; i++) {
1969                         if (same(stages[i], head)) {
1970                                 head_match = i;
1971                         }
1972                         if (same(stages[i], remote)) {
1973                                 remote_match = i;
1974                         }
1975                 }
1976         }
1977
1978         /*
1979          * We start with cases where the index is allowed to match
1980          * something other than the head: #14(ALT) and #2ALT, where it
1981          * is permitted to match the result instead.
1982          */
1983         /* #14, #14ALT, #2ALT */
1984         if (remote && !df_conflict_head && head_match && !remote_match) {
1985                 if (index && !same(index, remote) && !same(index, head))
1986                         return reject_merge(index, o);
1987                 return merged_entry(remote, index, o);
1988         }
1989         /*
1990          * If we have an entry in the index cache, then we want to
1991          * make sure that it matches head.
1992          */
1993         if (index && !same(index, head))
1994                 return reject_merge(index, o);
1995
1996         if (head) {
1997                 /* #5ALT, #15 */
1998                 if (same(head, remote))
1999                         return merged_entry(head, index, o);
2000                 /* #13, #3ALT */
2001                 if (!df_conflict_remote && remote_match && !head_match)
2002                         return merged_entry(head, index, o);
2003         }
2004
2005         /* #1 */
2006         if (!head && !remote && any_anc_missing)
2007                 return 0;
2008
2009         /*
2010          * Under the "aggressive" rule, we resolve mostly trivial
2011          * cases that we historically had git-merge-one-file resolve.
2012          */
2013         if (o->aggressive) {
2014                 int head_deleted = !head;
2015                 int remote_deleted = !remote;
2016                 const struct cache_entry *ce = NULL;
2017
2018                 if (index)
2019                         ce = index;
2020                 else if (head)
2021                         ce = head;
2022                 else if (remote)
2023                         ce = remote;
2024                 else {
2025                         for (i = 1; i < o->head_idx; i++) {
2026                                 if (stages[i] && stages[i] != o->df_conflict_entry) {
2027                                         ce = stages[i];
2028                                         break;
2029                                 }
2030                         }
2031                 }
2032
2033                 /*
2034                  * Deleted in both.
2035                  * Deleted in one and unchanged in the other.
2036                  */
2037                 if ((head_deleted && remote_deleted) ||
2038                     (head_deleted && remote && remote_match) ||
2039                     (remote_deleted && head && head_match)) {
2040                         if (index)
2041                                 return deleted_entry(index, index, o);
2042                         if (ce && !head_deleted) {
2043                                 if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
2044                                         return -1;
2045                         }
2046                         return 0;
2047                 }
2048                 /*
2049                  * Added in both, identically.
2050                  */
2051                 if (no_anc_exists && head && remote && same(head, remote))
2052                         return merged_entry(head, index, o);
2053
2054         }
2055
2056         /* Below are "no merge" cases, which require that the index be
2057          * up-to-date to avoid the files getting overwritten with
2058          * conflict resolution files.
2059          */
2060         if (index) {
2061                 if (verify_uptodate(index, o))
2062                         return -1;
2063         }
2064
2065         o->nontrivial_merge = 1;
2066
2067         /* #2, #3, #4, #6, #7, #9, #10, #11. */
2068         count = 0;
2069         if (!head_match || !remote_match) {
2070                 for (i = 1; i < o->head_idx; i++) {
2071                         if (stages[i] && stages[i] != o->df_conflict_entry) {
2072                                 keep_entry(stages[i], o);
2073                                 count++;
2074                                 break;
2075                         }
2076                 }
2077         }
2078 #if DBRT_DEBUG
2079         else {
2080                 fprintf(stderr, "read-tree: warning #16 detected\n");
2081                 show_stage_entry(stderr, "head   ", stages[head_match]);
2082                 show_stage_entry(stderr, "remote ", stages[remote_match]);
2083         }
2084 #endif
2085         if (head) { count += keep_entry(head, o); }
2086         if (remote) { count += keep_entry(remote, o); }
2087         return count;
2088 }
2089
2090 /*
2091  * Two-way merge.
2092  *
2093  * The rule is to "carry forward" what is in the index without losing
2094  * information across a "fast-forward", favoring a successful merge
2095  * over a merge failure when it makes sense.  For details of the
2096  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
2097  *
2098  */
2099 int twoway_merge(const struct cache_entry * const *src,
2100                  struct unpack_trees_options *o)
2101 {
2102         const struct cache_entry *current = src[0];
2103         const struct cache_entry *oldtree = src[1];
2104         const struct cache_entry *newtree = src[2];
2105
2106         if (o->merge_size != 2)
2107                 return error("Cannot do a twoway merge of %d trees",
2108                              o->merge_size);
2109
2110         if (oldtree == o->df_conflict_entry)
2111                 oldtree = NULL;
2112         if (newtree == o->df_conflict_entry)
2113                 newtree = NULL;
2114
2115         if (current) {
2116                 if (current->ce_flags & CE_CONFLICTED) {
2117                         if (same(oldtree, newtree) || o->reset) {
2118                                 if (!newtree)
2119                                         return deleted_entry(current, current, o);
2120                                 else
2121                                         return merged_entry(newtree, current, o);
2122                         }
2123                         return reject_merge(current, o);
2124                 } else if ((!oldtree && !newtree) || /* 4 and 5 */
2125                          (!oldtree && newtree &&
2126                           same(current, newtree)) || /* 6 and 7 */
2127                          (oldtree && newtree &&
2128                           same(oldtree, newtree)) || /* 14 and 15 */
2129                          (oldtree && newtree &&
2130                           !same(oldtree, newtree) && /* 18 and 19 */
2131                           same(current, newtree))) {
2132                         return keep_entry(current, o);
2133                 } else if (oldtree && !newtree && same(current, oldtree)) {
2134                         /* 10 or 11 */
2135                         return deleted_entry(oldtree, current, o);
2136                 } else if (oldtree && newtree &&
2137                          same(current, oldtree) && !same(current, newtree)) {
2138                         /* 20 or 21 */
2139                         return merged_entry(newtree, current, o);
2140                 } else
2141                         return reject_merge(current, o);
2142         }
2143         else if (newtree) {
2144                 if (oldtree && !o->initial_checkout) {
2145                         /*
2146                          * deletion of the path was staged;
2147                          */
2148                         if (same(oldtree, newtree))
2149                                 return 1;
2150                         return reject_merge(oldtree, o);
2151                 }
2152                 return merged_entry(newtree, current, o);
2153         }
2154         return deleted_entry(oldtree, current, o);
2155 }
2156
2157 /*
2158  * Bind merge.
2159  *
2160  * Keep the index entries at stage0, collapse stage1 but make sure
2161  * stage0 does not have anything there.
2162  */
2163 int bind_merge(const struct cache_entry * const *src,
2164                struct unpack_trees_options *o)
2165 {
2166         const struct cache_entry *old = src[0];
2167         const struct cache_entry *a = src[1];
2168
2169         if (o->merge_size != 1)
2170                 return error("Cannot do a bind merge of %d trees",
2171                              o->merge_size);
2172         if (a && old)
2173                 return o->gently ? -1 :
2174                         error(ERRORMSG(o, ERROR_BIND_OVERLAP),
2175                               super_prefixed(a->name),
2176                               super_prefixed(old->name));
2177         if (!a)
2178                 return keep_entry(old, o);
2179         else
2180                 return merged_entry(a, NULL, o);
2181 }
2182
2183 /*
2184  * One-way merge.
2185  *
2186  * The rule is:
2187  * - take the stat information from stage0, take the data from stage1
2188  */
2189 int oneway_merge(const struct cache_entry * const *src,
2190                  struct unpack_trees_options *o)
2191 {
2192         const struct cache_entry *old = src[0];
2193         const struct cache_entry *a = src[1];
2194
2195         if (o->merge_size != 1)
2196                 return error("Cannot do a oneway merge of %d trees",
2197                              o->merge_size);
2198
2199         if (!a || a == o->df_conflict_entry)
2200                 return deleted_entry(old, old, o);
2201
2202         if (old && same(old, a)) {
2203                 int update = 0;
2204                 if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
2205                         struct stat st;
2206                         if (lstat(old->name, &st) ||
2207                             ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
2208                                 update |= CE_UPDATE;
2209                 }
2210                 if (o->update && S_ISGITLINK(old->ce_mode) &&
2211                     should_update_submodules() && !verify_uptodate(old, o))
2212                         update |= CE_UPDATE;
2213                 add_entry(o, old, update, 0);
2214                 return 0;
2215         }
2216         return merged_entry(a, old, o);
2217 }