unpack-trees.con commit commit: allow lookup_commit_graft to handle arbitrary repositories (b9dbddf)
   1#define NO_THE_INDEX_COMPATIBILITY_MACROS
   2#include "cache.h"
   3#include "repository.h"
   4#include "config.h"
   5#include "dir.h"
   6#include "tree.h"
   7#include "tree-walk.h"
   8#include "cache-tree.h"
   9#include "unpack-trees.h"
  10#include "progress.h"
  11#include "refs.h"
  12#include "attr.h"
  13#include "split-index.h"
  14#include "dir.h"
  15#include "submodule.h"
  16#include "submodule-config.h"
  17#include "fsmonitor.h"
  18#include "object-store.h"
  19#include "fetch-object.h"
  20
  21/*
  22 * Error messages expected by scripts out of plumbing commands such as
  23 * read-tree.  Non-scripted Porcelain is not required to use these messages
  24 * and in fact are encouraged to reword them to better suit their particular
  25 * situation better.  See how "git checkout" and "git merge" replaces
  26 * them using setup_unpack_trees_porcelain(), for example.
  27 */
  28static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
  29        /* ERROR_WOULD_OVERWRITE */
  30        "Entry '%s' would be overwritten by merge. Cannot merge.",
  31
  32        /* ERROR_NOT_UPTODATE_FILE */
  33        "Entry '%s' not uptodate. Cannot merge.",
  34
  35        /* ERROR_NOT_UPTODATE_DIR */
  36        "Updating '%s' would lose untracked files in it",
  37
  38        /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
  39        "Untracked working tree file '%s' would be overwritten by merge.",
  40
  41        /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
  42        "Untracked working tree file '%s' would be removed by merge.",
  43
  44        /* ERROR_BIND_OVERLAP */
  45        "Entry '%s' overlaps with '%s'.  Cannot bind.",
  46
  47        /* ERROR_SPARSE_NOT_UPTODATE_FILE */
  48        "Entry '%s' not uptodate. Cannot update sparse checkout.",
  49
  50        /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
  51        "Working tree file '%s' would be overwritten by sparse checkout update.",
  52
  53        /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
  54        "Working tree file '%s' would be removed by sparse checkout update.",
  55
  56        /* ERROR_WOULD_LOSE_SUBMODULE */
  57        "Submodule '%s' cannot checkout new HEAD.",
  58};
  59
  60#define ERRORMSG(o,type) \
  61        ( ((o) && (o)->msgs[(type)]) \
  62          ? ((o)->msgs[(type)])      \
  63          : (unpack_plumbing_errors[(type)]) )
  64
  65static const char *super_prefixed(const char *path)
  66{
  67        /*
  68         * It is necessary and sufficient to have two static buffers
  69         * here, as the return value of this function is fed to
  70         * error() using the unpack_*_errors[] templates we see above.
  71         */
  72        static struct strbuf buf[2] = {STRBUF_INIT, STRBUF_INIT};
  73        static int super_prefix_len = -1;
  74        static unsigned idx = ARRAY_SIZE(buf) - 1;
  75
  76        if (super_prefix_len < 0) {
  77                const char *super_prefix = get_super_prefix();
  78                if (!super_prefix) {
  79                        super_prefix_len = 0;
  80                } else {
  81                        int i;
  82                        for (i = 0; i < ARRAY_SIZE(buf); i++)
  83                                strbuf_addstr(&buf[i], super_prefix);
  84                        super_prefix_len = buf[0].len;
  85                }
  86        }
  87
  88        if (!super_prefix_len)
  89                return path;
  90
  91        if (++idx >= ARRAY_SIZE(buf))
  92                idx = 0;
  93
  94        strbuf_setlen(&buf[idx], super_prefix_len);
  95        strbuf_addstr(&buf[idx], path);
  96
  97        return buf[idx].buf;
  98}
  99
 100void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
 101                                  const char *cmd)
 102{
 103        int i;
 104        const char **msgs = opts->msgs;
 105        const char *msg;
 106
 107        if (!strcmp(cmd, "checkout"))
 108                msg = advice_commit_before_merge
 109                      ? _("Your local changes to the following files would be overwritten by checkout:\n%%s"
 110                          "Please commit your changes or stash them before you switch branches.")
 111                      : _("Your local changes to the following files would be overwritten by checkout:\n%%s");
 112        else if (!strcmp(cmd, "merge"))
 113                msg = advice_commit_before_merge
 114                      ? _("Your local changes to the following files would be overwritten by merge:\n%%s"
 115                          "Please commit your changes or stash them before you merge.")
 116                      : _("Your local changes to the following files would be overwritten by merge:\n%%s");
 117        else
 118                msg = advice_commit_before_merge
 119                      ? _("Your local changes to the following files would be overwritten by %s:\n%%s"
 120                          "Please commit your changes or stash them before you %s.")
 121                      : _("Your local changes to the following files would be overwritten by %s:\n%%s");
 122        msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
 123                xstrfmt(msg, cmd, cmd);
 124
 125        msgs[ERROR_NOT_UPTODATE_DIR] =
 126                _("Updating the following directories would lose untracked files in them:\n%s");
 127
 128        if (!strcmp(cmd, "checkout"))
 129                msg = advice_commit_before_merge
 130                      ? _("The following untracked working tree files would be removed by checkout:\n%%s"
 131                          "Please move or remove them before you switch branches.")
 132                      : _("The following untracked working tree files would be removed by checkout:\n%%s");
 133        else if (!strcmp(cmd, "merge"))
 134                msg = advice_commit_before_merge
 135                      ? _("The following untracked working tree files would be removed by merge:\n%%s"
 136                          "Please move or remove them before you merge.")
 137                      : _("The following untracked working tree files would be removed by merge:\n%%s");
 138        else
 139                msg = advice_commit_before_merge
 140                      ? _("The following untracked working tree files would be removed by %s:\n%%s"
 141                          "Please move or remove them before you %s.")
 142                      : _("The following untracked working tree files would be removed by %s:\n%%s");
 143        msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] = xstrfmt(msg, cmd, cmd);
 144
 145        if (!strcmp(cmd, "checkout"))
 146                msg = advice_commit_before_merge
 147                      ? _("The following untracked working tree files would be overwritten by checkout:\n%%s"
 148                          "Please move or remove them before you switch branches.")
 149                      : _("The following untracked working tree files would be overwritten by checkout:\n%%s");
 150        else if (!strcmp(cmd, "merge"))
 151                msg = advice_commit_before_merge
 152                      ? _("The following untracked working tree files would be overwritten by merge:\n%%s"
 153                          "Please move or remove them before you merge.")
 154                      : _("The following untracked working tree files would be overwritten by merge:\n%%s");
 155        else
 156                msg = advice_commit_before_merge
 157                      ? _("The following untracked working tree files would be overwritten by %s:\n%%s"
 158                          "Please move or remove them before you %s.")
 159                      : _("The following untracked working tree files would be overwritten by %s:\n%%s");
 160        msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] = xstrfmt(msg, cmd, cmd);
 161
 162        /*
 163         * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
 164         * cannot easily display it as a list.
 165         */
 166        msgs[ERROR_BIND_OVERLAP] = _("Entry '%s' overlaps with '%s'.  Cannot bind.");
 167
 168        msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
 169                _("Cannot update sparse checkout: the following entries are not up to date:\n%s");
 170        msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
 171                _("The following working tree files would be overwritten by sparse checkout update:\n%s");
 172        msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
 173                _("The following working tree files would be removed by sparse checkout update:\n%s");
 174        msgs[ERROR_WOULD_LOSE_SUBMODULE] =
 175                _("Cannot update submodule:\n%s");
 176
 177        opts->show_all_errors = 1;
 178        /* rejected paths may not have a static buffer */
 179        for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
 180                opts->unpack_rejects[i].strdup_strings = 1;
 181}
 182
 183static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
 184                         unsigned int set, unsigned int clear)
 185{
 186        clear |= CE_HASHED;
 187
 188        if (set & CE_REMOVE)
 189                set |= CE_WT_REMOVE;
 190
 191        ce->ce_flags = (ce->ce_flags & ~clear) | set;
 192        return add_index_entry(&o->result, ce,
 193                               ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 194}
 195
 196static struct cache_entry *dup_entry(const struct cache_entry *ce)
 197{
 198        unsigned int size = ce_size(ce);
 199        struct cache_entry *new_entry = xmalloc(size);
 200
 201        memcpy(new_entry, ce, size);
 202        return new_entry;
 203}
 204
 205static void add_entry(struct unpack_trees_options *o,
 206                      const struct cache_entry *ce,
 207                      unsigned int set, unsigned int clear)
 208{
 209        do_add_entry(o, dup_entry(ce), set, clear);
 210}
 211
 212/*
 213 * add error messages on path <path>
 214 * corresponding to the type <e> with the message <msg>
 215 * indicating if it should be display in porcelain or not
 216 */
 217static int add_rejected_path(struct unpack_trees_options *o,
 218                             enum unpack_trees_error_types e,
 219                             const char *path)
 220{
 221        if (!o->show_all_errors)
 222                return error(ERRORMSG(o, e), super_prefixed(path));
 223
 224        /*
 225         * Otherwise, insert in a list for future display by
 226         * display_error_msgs()
 227         */
 228        string_list_append(&o->unpack_rejects[e], path);
 229        return -1;
 230}
 231
 232/*
 233 * display all the error messages stored in a nice way
 234 */
 235static void display_error_msgs(struct unpack_trees_options *o)
 236{
 237        int e, i;
 238        int something_displayed = 0;
 239        for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
 240                struct string_list *rejects = &o->unpack_rejects[e];
 241                if (rejects->nr > 0) {
 242                        struct strbuf path = STRBUF_INIT;
 243                        something_displayed = 1;
 244                        for (i = 0; i < rejects->nr; i++)
 245                                strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
 246                        error(ERRORMSG(o, e), super_prefixed(path.buf));
 247                        strbuf_release(&path);
 248                }
 249                string_list_clear(rejects, 0);
 250        }
 251        if (something_displayed)
 252                fprintf(stderr, _("Aborting\n"));
 253}
 254
 255static int check_submodule_move_head(const struct cache_entry *ce,
 256                                     const char *old_id,
 257                                     const char *new_id,
 258                                     struct unpack_trees_options *o)
 259{
 260        unsigned flags = SUBMODULE_MOVE_HEAD_DRY_RUN;
 261        const struct submodule *sub = submodule_from_ce(ce);
 262
 263        if (!sub)
 264                return 0;
 265
 266        if (o->reset)
 267                flags |= SUBMODULE_MOVE_HEAD_FORCE;
 268
 269        if (submodule_move_head(ce->name, old_id, new_id, flags))
 270                return o->gently ? -1 :
 271                                   add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
 272        return 0;
 273}
 274
 275/*
 276 * Preform the loading of the repository's gitmodules file.  This function is
 277 * used by 'check_update()' to perform loading of the gitmodules file in two
 278 * differnt situations:
 279 * (1) before removing entries from the working tree if the gitmodules file has
 280 *     been marked for removal.  This situation is specified by 'state' == NULL.
 281 * (2) before checking out entries to the working tree if the gitmodules file
 282 *     has been marked for update.  This situation is specified by 'state' != NULL.
 283 */
 284static void load_gitmodules_file(struct index_state *index,
 285                                 struct checkout *state)
 286{
 287        int pos = index_name_pos(index, GITMODULES_FILE, strlen(GITMODULES_FILE));
 288
 289        if (pos >= 0) {
 290                struct cache_entry *ce = index->cache[pos];
 291                if (!state && ce->ce_flags & CE_WT_REMOVE) {
 292                        repo_read_gitmodules(the_repository);
 293                } else if (state && (ce->ce_flags & CE_UPDATE)) {
 294                        submodule_free();
 295                        checkout_entry(ce, state, NULL);
 296                        repo_read_gitmodules(the_repository);
 297                }
 298        }
 299}
 300
 301/*
 302 * Unlink the last component and schedule the leading directories for
 303 * removal, such that empty directories get removed.
 304 */
 305static void unlink_entry(const struct cache_entry *ce)
 306{
 307        const struct submodule *sub = submodule_from_ce(ce);
 308        if (sub) {
 309                /* state.force is set at the caller. */
 310                submodule_move_head(ce->name, "HEAD", NULL,
 311                                    SUBMODULE_MOVE_HEAD_FORCE);
 312        }
 313        if (!check_leading_path(ce->name, ce_namelen(ce)))
 314                return;
 315        if (remove_or_warn(ce->ce_mode, ce->name))
 316                return;
 317        schedule_dir_for_removal(ce->name, ce_namelen(ce));
 318}
 319
 320static struct progress *get_progress(struct unpack_trees_options *o)
 321{
 322        unsigned cnt = 0, total = 0;
 323        struct index_state *index = &o->result;
 324
 325        if (!o->update || !o->verbose_update)
 326                return NULL;
 327
 328        for (; cnt < index->cache_nr; cnt++) {
 329                const struct cache_entry *ce = index->cache[cnt];
 330                if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
 331                        total++;
 332        }
 333
 334        return start_delayed_progress(_("Checking out files"), total);
 335}
 336
 337static int check_updates(struct unpack_trees_options *o)
 338{
 339        unsigned cnt = 0;
 340        int errs = 0;
 341        struct progress *progress = NULL;
 342        struct index_state *index = &o->result;
 343        struct checkout state = CHECKOUT_INIT;
 344        int i;
 345
 346        state.force = 1;
 347        state.quiet = 1;
 348        state.refresh_cache = 1;
 349        state.istate = index;
 350
 351        progress = get_progress(o);
 352
 353        if (o->update)
 354                git_attr_set_direction(GIT_ATTR_CHECKOUT, index);
 355
 356        if (should_update_submodules() && o->update && !o->dry_run)
 357                load_gitmodules_file(index, NULL);
 358
 359        for (i = 0; i < index->cache_nr; i++) {
 360                const struct cache_entry *ce = index->cache[i];
 361
 362                if (ce->ce_flags & CE_WT_REMOVE) {
 363                        display_progress(progress, ++cnt);
 364                        if (o->update && !o->dry_run)
 365                                unlink_entry(ce);
 366                }
 367        }
 368        remove_marked_cache_entries(index);
 369        remove_scheduled_dirs();
 370
 371        if (should_update_submodules() && o->update && !o->dry_run)
 372                load_gitmodules_file(index, &state);
 373
 374        enable_delayed_checkout(&state);
 375        if (repository_format_partial_clone && o->update && !o->dry_run) {
 376                /*
 377                 * Prefetch the objects that are to be checked out in the loop
 378                 * below.
 379                 */
 380                struct oid_array to_fetch = OID_ARRAY_INIT;
 381                int fetch_if_missing_store = fetch_if_missing;
 382                fetch_if_missing = 0;
 383                for (i = 0; i < index->cache_nr; i++) {
 384                        struct cache_entry *ce = index->cache[i];
 385                        if ((ce->ce_flags & CE_UPDATE) &&
 386                            !S_ISGITLINK(ce->ce_mode)) {
 387                                if (!has_object_file(&ce->oid))
 388                                        oid_array_append(&to_fetch, &ce->oid);
 389                        }
 390                }
 391                if (to_fetch.nr)
 392                        fetch_objects(repository_format_partial_clone,
 393                                      &to_fetch);
 394                fetch_if_missing = fetch_if_missing_store;
 395                oid_array_clear(&to_fetch);
 396        }
 397        for (i = 0; i < index->cache_nr; i++) {
 398                struct cache_entry *ce = index->cache[i];
 399
 400                if (ce->ce_flags & CE_UPDATE) {
 401                        if (ce->ce_flags & CE_WT_REMOVE)
 402                                die("BUG: both update and delete flags are set on %s",
 403                                    ce->name);
 404                        display_progress(progress, ++cnt);
 405                        ce->ce_flags &= ~CE_UPDATE;
 406                        if (o->update && !o->dry_run) {
 407                                errs |= checkout_entry(ce, &state, NULL);
 408                        }
 409                }
 410        }
 411        stop_progress(&progress);
 412        errs |= finish_delayed_checkout(&state);
 413        if (o->update)
 414                git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
 415        return errs != 0;
 416}
 417
 418static int verify_uptodate_sparse(const struct cache_entry *ce,
 419                                  struct unpack_trees_options *o);
 420static int verify_absent_sparse(const struct cache_entry *ce,
 421                                enum unpack_trees_error_types,
 422                                struct unpack_trees_options *o);
 423
 424static int apply_sparse_checkout(struct index_state *istate,
 425                                 struct cache_entry *ce,
 426                                 struct unpack_trees_options *o)
 427{
 428        int was_skip_worktree = ce_skip_worktree(ce);
 429
 430        if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
 431                ce->ce_flags |= CE_SKIP_WORKTREE;
 432        else
 433                ce->ce_flags &= ~CE_SKIP_WORKTREE;
 434        if (was_skip_worktree != ce_skip_worktree(ce)) {
 435                ce->ce_flags |= CE_UPDATE_IN_BASE;
 436                mark_fsmonitor_invalid(istate, ce);
 437                istate->cache_changed |= CE_ENTRY_CHANGED;
 438        }
 439
 440        /*
 441         * if (!was_skip_worktree && !ce_skip_worktree()) {
 442         *      This is perfectly normal. Move on;
 443         * }
 444         */
 445
 446        /*
 447         * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
 448         * area as a result of ce_skip_worktree() shortcuts in
 449         * verify_absent() and verify_uptodate().
 450         * Make sure they don't modify worktree if they are already
 451         * outside checkout area
 452         */
 453        if (was_skip_worktree && ce_skip_worktree(ce)) {
 454                ce->ce_flags &= ~CE_UPDATE;
 455
 456                /*
 457                 * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
 458                 * on to get that file removed from both index and worktree.
 459                 * If that file is already outside worktree area, don't
 460                 * bother remove it.
 461                 */
 462                if (ce->ce_flags & CE_REMOVE)
 463                        ce->ce_flags &= ~CE_WT_REMOVE;
 464        }
 465
 466        if (!was_skip_worktree && ce_skip_worktree(ce)) {
 467                /*
 468                 * If CE_UPDATE is set, verify_uptodate() must be called already
 469                 * also stat info may have lost after merged_entry() so calling
 470                 * verify_uptodate() again may fail
 471                 */
 472                if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
 473                        return -1;
 474                ce->ce_flags |= CE_WT_REMOVE;
 475                ce->ce_flags &= ~CE_UPDATE;
 476        }
 477        if (was_skip_worktree && !ce_skip_worktree(ce)) {
 478                if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
 479                        return -1;
 480                ce->ce_flags |= CE_UPDATE;
 481        }
 482        return 0;
 483}
 484
 485static inline int call_unpack_fn(const struct cache_entry * const *src,
 486                                 struct unpack_trees_options *o)
 487{
 488        int ret = o->fn(src, o);
 489        if (ret > 0)
 490                ret = 0;
 491        return ret;
 492}
 493
 494static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
 495{
 496        ce->ce_flags |= CE_UNPACKED;
 497
 498        if (o->cache_bottom < o->src_index->cache_nr &&
 499            o->src_index->cache[o->cache_bottom] == ce) {
 500                int bottom = o->cache_bottom;
 501                while (bottom < o->src_index->cache_nr &&
 502                       o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
 503                        bottom++;
 504                o->cache_bottom = bottom;
 505        }
 506}
 507
 508static void mark_all_ce_unused(struct index_state *index)
 509{
 510        int i;
 511        for (i = 0; i < index->cache_nr; i++)
 512                index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
 513}
 514
 515static int locate_in_src_index(const struct cache_entry *ce,
 516                               struct unpack_trees_options *o)
 517{
 518        struct index_state *index = o->src_index;
 519        int len = ce_namelen(ce);
 520        int pos = index_name_pos(index, ce->name, len);
 521        if (pos < 0)
 522                pos = -1 - pos;
 523        return pos;
 524}
 525
 526/*
 527 * We call unpack_index_entry() with an unmerged cache entry
 528 * only in diff-index, and it wants a single callback.  Skip
 529 * the other unmerged entry with the same name.
 530 */
 531static void mark_ce_used_same_name(struct cache_entry *ce,
 532                                   struct unpack_trees_options *o)
 533{
 534        struct index_state *index = o->src_index;
 535        int len = ce_namelen(ce);
 536        int pos;
 537
 538        for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
 539                struct cache_entry *next = index->cache[pos];
 540                if (len != ce_namelen(next) ||
 541                    memcmp(ce->name, next->name, len))
 542                        break;
 543                mark_ce_used(next, o);
 544        }
 545}
 546
 547static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
 548{
 549        const struct index_state *index = o->src_index;
 550        int pos = o->cache_bottom;
 551
 552        while (pos < index->cache_nr) {
 553                struct cache_entry *ce = index->cache[pos];
 554                if (!(ce->ce_flags & CE_UNPACKED))
 555                        return ce;
 556                pos++;
 557        }
 558        return NULL;
 559}
 560
 561static void add_same_unmerged(const struct cache_entry *ce,
 562                              struct unpack_trees_options *o)
 563{
 564        struct index_state *index = o->src_index;
 565        int len = ce_namelen(ce);
 566        int pos = index_name_pos(index, ce->name, len);
 567
 568        if (0 <= pos)
 569                die("programming error in a caller of mark_ce_used_same_name");
 570        for (pos = -pos - 1; pos < index->cache_nr; pos++) {
 571                struct cache_entry *next = index->cache[pos];
 572                if (len != ce_namelen(next) ||
 573                    memcmp(ce->name, next->name, len))
 574                        break;
 575                add_entry(o, next, 0, 0);
 576                mark_ce_used(next, o);
 577        }
 578}
 579
 580static int unpack_index_entry(struct cache_entry *ce,
 581                              struct unpack_trees_options *o)
 582{
 583        const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 584        int ret;
 585
 586        src[0] = ce;
 587
 588        mark_ce_used(ce, o);
 589        if (ce_stage(ce)) {
 590                if (o->skip_unmerged) {
 591                        add_entry(o, ce, 0, 0);
 592                        return 0;
 593                }
 594        }
 595        ret = call_unpack_fn(src, o);
 596        if (ce_stage(ce))
 597                mark_ce_used_same_name(ce, o);
 598        return ret;
 599}
 600
 601static int find_cache_pos(struct traverse_info *, const struct name_entry *);
 602
 603static void restore_cache_bottom(struct traverse_info *info, int bottom)
 604{
 605        struct unpack_trees_options *o = info->data;
 606
 607        if (o->diff_index_cached)
 608                return;
 609        o->cache_bottom = bottom;
 610}
 611
 612static int switch_cache_bottom(struct traverse_info *info)
 613{
 614        struct unpack_trees_options *o = info->data;
 615        int ret, pos;
 616
 617        if (o->diff_index_cached)
 618                return 0;
 619        ret = o->cache_bottom;
 620        pos = find_cache_pos(info->prev, &info->name);
 621
 622        if (pos < -1)
 623                o->cache_bottom = -2 - pos;
 624        else if (pos < 0)
 625                o->cache_bottom = o->src_index->cache_nr;
 626        return ret;
 627}
 628
 629static inline int are_same_oid(struct name_entry *name_j, struct name_entry *name_k)
 630{
 631        return name_j->oid && name_k->oid && !oidcmp(name_j->oid, name_k->oid);
 632}
 633
 634static int traverse_trees_recursive(int n, unsigned long dirmask,
 635                                    unsigned long df_conflicts,
 636                                    struct name_entry *names,
 637                                    struct traverse_info *info)
 638{
 639        int i, ret, bottom;
 640        int nr_buf = 0;
 641        struct tree_desc t[MAX_UNPACK_TREES];
 642        void *buf[MAX_UNPACK_TREES];
 643        struct traverse_info newinfo;
 644        struct name_entry *p;
 645
 646        p = names;
 647        while (!p->mode)
 648                p++;
 649
 650        newinfo = *info;
 651        newinfo.prev = info;
 652        newinfo.pathspec = info->pathspec;
 653        newinfo.name = *p;
 654        newinfo.pathlen += tree_entry_len(p) + 1;
 655        newinfo.df_conflicts |= df_conflicts;
 656
 657        /*
 658         * Fetch the tree from the ODB for each peer directory in the
 659         * n commits.
 660         *
 661         * For 2- and 3-way traversals, we try to avoid hitting the
 662         * ODB twice for the same OID.  This should yield a nice speed
 663         * up in checkouts and merges when the commits are similar.
 664         *
 665         * We don't bother doing the full O(n^2) search for larger n,
 666         * because wider traversals don't happen that often and we
 667         * avoid the search setup.
 668         *
 669         * When 2 peer OIDs are the same, we just copy the tree
 670         * descriptor data.  This implicitly borrows the buffer
 671         * data from the earlier cell.
 672         */
 673        for (i = 0; i < n; i++, dirmask >>= 1) {
 674                if (i > 0 && are_same_oid(&names[i], &names[i - 1]))
 675                        t[i] = t[i - 1];
 676                else if (i > 1 && are_same_oid(&names[i], &names[i - 2]))
 677                        t[i] = t[i - 2];
 678                else {
 679                        const struct object_id *oid = NULL;
 680                        if (dirmask & 1)
 681                                oid = names[i].oid;
 682                        buf[nr_buf++] = fill_tree_descriptor(t + i, oid);
 683                }
 684        }
 685
 686        bottom = switch_cache_bottom(&newinfo);
 687        ret = traverse_trees(n, t, &newinfo);
 688        restore_cache_bottom(&newinfo, bottom);
 689
 690        for (i = 0; i < nr_buf; i++)
 691                free(buf[i]);
 692
 693        return ret;
 694}
 695
 696/*
 697 * Compare the traverse-path to the cache entry without actually
 698 * having to generate the textual representation of the traverse
 699 * path.
 700 *
 701 * NOTE! This *only* compares up to the size of the traverse path
 702 * itself - the caller needs to do the final check for the cache
 703 * entry having more data at the end!
 704 */
 705static int do_compare_entry_piecewise(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 706{
 707        int len, pathlen, ce_len;
 708        const char *ce_name;
 709
 710        if (info->prev) {
 711                int cmp = do_compare_entry_piecewise(ce, info->prev,
 712                                                     &info->name);
 713                if (cmp)
 714                        return cmp;
 715        }
 716        pathlen = info->pathlen;
 717        ce_len = ce_namelen(ce);
 718
 719        /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 720        if (ce_len < pathlen)
 721                return -1;
 722
 723        ce_len -= pathlen;
 724        ce_name = ce->name + pathlen;
 725
 726        len = tree_entry_len(n);
 727        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 728}
 729
 730static int do_compare_entry(const struct cache_entry *ce,
 731                            const struct traverse_info *info,
 732                            const struct name_entry *n)
 733{
 734        int len, pathlen, ce_len;
 735        const char *ce_name;
 736        int cmp;
 737
 738        /*
 739         * If we have not precomputed the traverse path, it is quicker
 740         * to avoid doing so.  But if we have precomputed it,
 741         * it is quicker to use the precomputed version.
 742         */
 743        if (!info->traverse_path)
 744                return do_compare_entry_piecewise(ce, info, n);
 745
 746        cmp = strncmp(ce->name, info->traverse_path, info->pathlen);
 747        if (cmp)
 748                return cmp;
 749
 750        pathlen = info->pathlen;
 751        ce_len = ce_namelen(ce);
 752
 753        if (ce_len < pathlen)
 754                return -1;
 755
 756        ce_len -= pathlen;
 757        ce_name = ce->name + pathlen;
 758
 759        len = tree_entry_len(n);
 760        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 761}
 762
 763static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 764{
 765        int cmp = do_compare_entry(ce, info, n);
 766        if (cmp)
 767                return cmp;
 768
 769        /*
 770         * Even if the beginning compared identically, the ce should
 771         * compare as bigger than a directory leading up to it!
 772         */
 773        return ce_namelen(ce) > traverse_path_len(info, n);
 774}
 775
 776static int ce_in_traverse_path(const struct cache_entry *ce,
 777                               const struct traverse_info *info)
 778{
 779        if (!info->prev)
 780                return 1;
 781        if (do_compare_entry(ce, info->prev, &info->name))
 782                return 0;
 783        /*
 784         * If ce (blob) is the same name as the path (which is a tree
 785         * we will be descending into), it won't be inside it.
 786         */
 787        return (info->pathlen < ce_namelen(ce));
 788}
 789
 790static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
 791{
 792        int len = traverse_path_len(info, n);
 793        struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
 794
 795        ce->ce_mode = create_ce_mode(n->mode);
 796        ce->ce_flags = create_ce_flags(stage);
 797        ce->ce_namelen = len;
 798        oidcpy(&ce->oid, n->oid);
 799        make_traverse_path(ce->name, info, n);
 800
 801        return ce;
 802}
 803
 804static int unpack_nondirectories(int n, unsigned long mask,
 805                                 unsigned long dirmask,
 806                                 struct cache_entry **src,
 807                                 const struct name_entry *names,
 808                                 const struct traverse_info *info)
 809{
 810        int i;
 811        struct unpack_trees_options *o = info->data;
 812        unsigned long conflicts = info->df_conflicts | dirmask;
 813
 814        /* Do we have *only* directories? Nothing to do */
 815        if (mask == dirmask && !src[0])
 816                return 0;
 817
 818        /*
 819         * Ok, we've filled in up to any potential index entry in src[0],
 820         * now do the rest.
 821         */
 822        for (i = 0; i < n; i++) {
 823                int stage;
 824                unsigned int bit = 1ul << i;
 825                if (conflicts & bit) {
 826                        src[i + o->merge] = o->df_conflict_entry;
 827                        continue;
 828                }
 829                if (!(mask & bit))
 830                        continue;
 831                if (!o->merge)
 832                        stage = 0;
 833                else if (i + 1 < o->head_idx)
 834                        stage = 1;
 835                else if (i + 1 > o->head_idx)
 836                        stage = 3;
 837                else
 838                        stage = 2;
 839                src[i + o->merge] = create_ce_entry(info, names + i, stage);
 840        }
 841
 842        if (o->merge) {
 843                int rc = call_unpack_fn((const struct cache_entry * const *)src,
 844                                        o);
 845                for (i = 0; i < n; i++) {
 846                        struct cache_entry *ce = src[i + o->merge];
 847                        if (ce != o->df_conflict_entry)
 848                                free(ce);
 849                }
 850                return rc;
 851        }
 852
 853        for (i = 0; i < n; i++)
 854                if (src[i] && src[i] != o->df_conflict_entry)
 855                        if (do_add_entry(o, src[i], 0, 0))
 856                                return -1;
 857
 858        return 0;
 859}
 860
 861static int unpack_failed(struct unpack_trees_options *o, const char *message)
 862{
 863        discard_index(&o->result);
 864        if (!o->gently && !o->exiting_early) {
 865                if (message)
 866                        return error("%s", message);
 867                return -1;
 868        }
 869        return -1;
 870}
 871
 872/*
 873 * The tree traversal is looking at name p.  If we have a matching entry,
 874 * return it.  If name p is a directory in the index, do not return
 875 * anything, as we will want to match it when the traversal descends into
 876 * the directory.
 877 */
 878static int find_cache_pos(struct traverse_info *info,
 879                          const struct name_entry *p)
 880{
 881        int pos;
 882        struct unpack_trees_options *o = info->data;
 883        struct index_state *index = o->src_index;
 884        int pfxlen = info->pathlen;
 885        int p_len = tree_entry_len(p);
 886
 887        for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
 888                const struct cache_entry *ce = index->cache[pos];
 889                const char *ce_name, *ce_slash;
 890                int cmp, ce_len;
 891
 892                if (ce->ce_flags & CE_UNPACKED) {
 893                        /*
 894                         * cache_bottom entry is already unpacked, so
 895                         * we can never match it; don't check it
 896                         * again.
 897                         */
 898                        if (pos == o->cache_bottom)
 899                                ++o->cache_bottom;
 900                        continue;
 901                }
 902                if (!ce_in_traverse_path(ce, info)) {
 903                        /*
 904                         * Check if we can skip future cache checks
 905                         * (because we're already past all possible
 906                         * entries in the traverse path).
 907                         */
 908                        if (info->traverse_path) {
 909                                if (strncmp(ce->name, info->traverse_path,
 910                                            info->pathlen) > 0)
 911                                        break;
 912                        }
 913                        continue;
 914                }
 915                ce_name = ce->name + pfxlen;
 916                ce_slash = strchr(ce_name, '/');
 917                if (ce_slash)
 918                        ce_len = ce_slash - ce_name;
 919                else
 920                        ce_len = ce_namelen(ce) - pfxlen;
 921                cmp = name_compare(p->path, p_len, ce_name, ce_len);
 922                /*
 923                 * Exact match; if we have a directory we need to
 924                 * delay returning it.
 925                 */
 926                if (!cmp)
 927                        return ce_slash ? -2 - pos : pos;
 928                if (0 < cmp)
 929                        continue; /* keep looking */
 930                /*
 931                 * ce_name sorts after p->path; could it be that we
 932                 * have files under p->path directory in the index?
 933                 * E.g.  ce_name == "t-i", and p->path == "t"; we may
 934                 * have "t/a" in the index.
 935                 */
 936                if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
 937                    ce_name[p_len] < '/')
 938                        continue; /* keep looking */
 939                break;
 940        }
 941        return -1;
 942}
 943
 944static struct cache_entry *find_cache_entry(struct traverse_info *info,
 945                                            const struct name_entry *p)
 946{
 947        int pos = find_cache_pos(info, p);
 948        struct unpack_trees_options *o = info->data;
 949
 950        if (0 <= pos)
 951                return o->src_index->cache[pos];
 952        else
 953                return NULL;
 954}
 955
 956static void debug_path(struct traverse_info *info)
 957{
 958        if (info->prev) {
 959                debug_path(info->prev);
 960                if (*info->prev->name.path)
 961                        putchar('/');
 962        }
 963        printf("%s", info->name.path);
 964}
 965
 966static void debug_name_entry(int i, struct name_entry *n)
 967{
 968        printf("ent#%d %06o %s\n", i,
 969               n->path ? n->mode : 0,
 970               n->path ? n->path : "(missing)");
 971}
 972
 973static void debug_unpack_callback(int n,
 974                                  unsigned long mask,
 975                                  unsigned long dirmask,
 976                                  struct name_entry *names,
 977                                  struct traverse_info *info)
 978{
 979        int i;
 980        printf("* unpack mask %lu, dirmask %lu, cnt %d ",
 981               mask, dirmask, n);
 982        debug_path(info);
 983        putchar('\n');
 984        for (i = 0; i < n; i++)
 985                debug_name_entry(i, names + i);
 986}
 987
 988static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
 989{
 990        struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 991        struct unpack_trees_options *o = info->data;
 992        const struct name_entry *p = names;
 993
 994        /* Find first entry with a real name (we could use "mask" too) */
 995        while (!p->mode)
 996                p++;
 997
 998        if (o->debug_unpack)
 999                debug_unpack_callback(n, mask, dirmask, names, info);
1000
1001        /* Are we supposed to look at the index too? */
1002        if (o->merge) {
1003                while (1) {
1004                        int cmp;
1005                        struct cache_entry *ce;
1006
1007                        if (o->diff_index_cached)
1008                                ce = next_cache_entry(o);
1009                        else
1010                                ce = find_cache_entry(info, p);
1011
1012                        if (!ce)
1013                                break;
1014                        cmp = compare_entry(ce, info, p);
1015                        if (cmp < 0) {
1016                                if (unpack_index_entry(ce, o) < 0)
1017                                        return unpack_failed(o, NULL);
1018                                continue;
1019                        }
1020                        if (!cmp) {
1021                                if (ce_stage(ce)) {
1022                                        /*
1023                                         * If we skip unmerged index
1024                                         * entries, we'll skip this
1025                                         * entry *and* the tree
1026                                         * entries associated with it!
1027                                         */
1028                                        if (o->skip_unmerged) {
1029                                                add_same_unmerged(ce, o);
1030                                                return mask;
1031                                        }
1032                                }
1033                                src[0] = ce;
1034                        }
1035                        break;
1036                }
1037        }
1038
1039        if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
1040                return -1;
1041
1042        if (o->merge && src[0]) {
1043                if (ce_stage(src[0]))
1044                        mark_ce_used_same_name(src[0], o);
1045                else
1046                        mark_ce_used(src[0], o);
1047        }
1048
1049        /* Now handle any directories.. */
1050        if (dirmask) {
1051                /* special case: "diff-index --cached" looking at a tree */
1052                if (o->diff_index_cached &&
1053                    n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
1054                        int matches;
1055                        matches = cache_tree_matches_traversal(o->src_index->cache_tree,
1056                                                               names, info);
1057                        /*
1058                         * Everything under the name matches; skip the
1059                         * entire hierarchy.  diff_index_cached codepath
1060                         * special cases D/F conflicts in such a way that
1061                         * it does not do any look-ahead, so this is safe.
1062                         */
1063                        if (matches) {
1064                                o->cache_bottom += matches;
1065                                return mask;
1066                        }
1067                }
1068
1069                if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
1070                                             names, info) < 0)
1071                        return -1;
1072                return mask;
1073        }
1074
1075        return mask;
1076}
1077
1078static int clear_ce_flags_1(struct cache_entry **cache, int nr,
1079                            struct strbuf *prefix,
1080                            int select_mask, int clear_mask,
1081                            struct exclude_list *el, int defval);
1082
1083/* Whole directory matching */
1084static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
1085                              struct strbuf *prefix,
1086                              char *basename,
1087                              int select_mask, int clear_mask,
1088                              struct exclude_list *el, int defval)
1089{
1090        struct cache_entry **cache_end;
1091        int dtype = DT_DIR;
1092        int ret = is_excluded_from_list(prefix->buf, prefix->len,
1093                                        basename, &dtype, el, &the_index);
1094        int rc;
1095
1096        strbuf_addch(prefix, '/');
1097
1098        /* If undecided, use matching result of parent dir in defval */
1099        if (ret < 0)
1100                ret = defval;
1101
1102        for (cache_end = cache; cache_end != cache + nr; cache_end++) {
1103                struct cache_entry *ce = *cache_end;
1104                if (strncmp(ce->name, prefix->buf, prefix->len))
1105                        break;
1106        }
1107
1108        /*
1109         * TODO: check el, if there are no patterns that may conflict
1110         * with ret (iow, we know in advance the incl/excl
1111         * decision for the entire directory), clear flag here without
1112         * calling clear_ce_flags_1(). That function will call
1113         * the expensive is_excluded_from_list() on every entry.
1114         */
1115        rc = clear_ce_flags_1(cache, cache_end - cache,
1116                              prefix,
1117                              select_mask, clear_mask,
1118                              el, ret);
1119        strbuf_setlen(prefix, prefix->len - 1);
1120        return rc;
1121}
1122
1123/*
1124 * Traverse the index, find every entry that matches according to
1125 * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
1126 * number of traversed entries.
1127 *
1128 * If select_mask is non-zero, only entries whose ce_flags has on of
1129 * those bits enabled are traversed.
1130 *
1131 * cache        : pointer to an index entry
1132 * prefix_len   : an offset to its path
1133 *
1134 * The current path ("prefix") including the trailing '/' is
1135 *   cache[0]->name[0..(prefix_len-1)]
1136 * Top level path has prefix_len zero.
1137 */
1138static int clear_ce_flags_1(struct cache_entry **cache, int nr,
1139                            struct strbuf *prefix,
1140                            int select_mask, int clear_mask,
1141                            struct exclude_list *el, int defval)
1142{
1143        struct cache_entry **cache_end = cache + nr;
1144
1145        /*
1146         * Process all entries that have the given prefix and meet
1147         * select_mask condition
1148         */
1149        while(cache != cache_end) {
1150                struct cache_entry *ce = *cache;
1151                const char *name, *slash;
1152                int len, dtype, ret;
1153
1154                if (select_mask && !(ce->ce_flags & select_mask)) {
1155                        cache++;
1156                        continue;
1157                }
1158
1159                if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
1160                        break;
1161
1162                name = ce->name + prefix->len;
1163                slash = strchr(name, '/');
1164
1165                /* If it's a directory, try whole directory match first */
1166                if (slash) {
1167                        int processed;
1168
1169                        len = slash - name;
1170                        strbuf_add(prefix, name, len);
1171
1172                        processed = clear_ce_flags_dir(cache, cache_end - cache,
1173                                                       prefix,
1174                                                       prefix->buf + prefix->len - len,
1175                                                       select_mask, clear_mask,
1176                                                       el, defval);
1177
1178                        /* clear_c_f_dir eats a whole dir already? */
1179                        if (processed) {
1180                                cache += processed;
1181                                strbuf_setlen(prefix, prefix->len - len);
1182                                continue;
1183                        }
1184
1185                        strbuf_addch(prefix, '/');
1186                        cache += clear_ce_flags_1(cache, cache_end - cache,
1187                                                  prefix,
1188                                                  select_mask, clear_mask, el, defval);
1189                        strbuf_setlen(prefix, prefix->len - len - 1);
1190                        continue;
1191                }
1192
1193                /* Non-directory */
1194                dtype = ce_to_dtype(ce);
1195                ret = is_excluded_from_list(ce->name, ce_namelen(ce),
1196                                            name, &dtype, el, &the_index);
1197                if (ret < 0)
1198                        ret = defval;
1199                if (ret > 0)
1200                        ce->ce_flags &= ~clear_mask;
1201                cache++;
1202        }
1203        return nr - (cache_end - cache);
1204}
1205
1206static int clear_ce_flags(struct cache_entry **cache, int nr,
1207                            int select_mask, int clear_mask,
1208                            struct exclude_list *el)
1209{
1210        static struct strbuf prefix = STRBUF_INIT;
1211
1212        strbuf_reset(&prefix);
1213
1214        return clear_ce_flags_1(cache, nr,
1215                                &prefix,
1216                                select_mask, clear_mask,
1217                                el, 0);
1218}
1219
1220/*
1221 * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
1222 */
1223static void mark_new_skip_worktree(struct exclude_list *el,
1224                                   struct index_state *the_index,
1225                                   int select_flag, int skip_wt_flag)
1226{
1227        int i;
1228
1229        /*
1230         * 1. Pretend the narrowest worktree: only unmerged entries
1231         * are checked out
1232         */
1233        for (i = 0; i < the_index->cache_nr; i++) {
1234                struct cache_entry *ce = the_index->cache[i];
1235
1236                if (select_flag && !(ce->ce_flags & select_flag))
1237                        continue;
1238
1239                if (!ce_stage(ce))
1240                        ce->ce_flags |= skip_wt_flag;
1241                else
1242                        ce->ce_flags &= ~skip_wt_flag;
1243        }
1244
1245        /*
1246         * 2. Widen worktree according to sparse-checkout file.
1247         * Matched entries will have skip_wt_flag cleared (i.e. "in")
1248         */
1249        clear_ce_flags(the_index->cache, the_index->cache_nr,
1250                       select_flag, skip_wt_flag, el);
1251}
1252
1253static int verify_absent(const struct cache_entry *,
1254                         enum unpack_trees_error_types,
1255                         struct unpack_trees_options *);
1256/*
1257 * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1258 * resulting index, -2 on failure to reflect the changes to the work tree.
1259 *
1260 * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1261 */
1262int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1263{
1264        int i, ret;
1265        static struct cache_entry *dfc;
1266        struct exclude_list el;
1267
1268        if (len > MAX_UNPACK_TREES)
1269                die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1270
1271        memset(&el, 0, sizeof(el));
1272        if (!core_apply_sparse_checkout || !o->update)
1273                o->skip_sparse_checkout = 1;
1274        if (!o->skip_sparse_checkout) {
1275                char *sparse = git_pathdup("info/sparse-checkout");
1276                if (add_excludes_from_file_to_list(sparse, "", 0, &el, NULL) < 0)
1277                        o->skip_sparse_checkout = 1;
1278                else
1279                        o->el = &el;
1280                free(sparse);
1281        }
1282
1283        memset(&o->result, 0, sizeof(o->result));
1284        o->result.initialized = 1;
1285        o->result.timestamp.sec = o->src_index->timestamp.sec;
1286        o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1287        o->result.version = o->src_index->version;
1288        o->result.split_index = o->src_index->split_index;
1289        if (o->result.split_index)
1290                o->result.split_index->refcount++;
1291        hashcpy(o->result.sha1, o->src_index->sha1);
1292        o->merge_size = len;
1293        mark_all_ce_unused(o->src_index);
1294
1295        /*
1296         * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1297         */
1298        if (!o->skip_sparse_checkout)
1299                mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1300
1301        if (!dfc)
1302                dfc = xcalloc(1, cache_entry_size(0));
1303        o->df_conflict_entry = dfc;
1304
1305        if (len) {
1306                const char *prefix = o->prefix ? o->prefix : "";
1307                struct traverse_info info;
1308
1309                setup_traverse_info(&info, prefix);
1310                info.fn = unpack_callback;
1311                info.data = o;
1312                info.show_all_errors = o->show_all_errors;
1313                info.pathspec = o->pathspec;
1314
1315                if (o->prefix) {
1316                        /*
1317                         * Unpack existing index entries that sort before the
1318                         * prefix the tree is spliced into.  Note that o->merge
1319                         * is always true in this case.
1320                         */
1321                        while (1) {
1322                                struct cache_entry *ce = next_cache_entry(o);
1323                                if (!ce)
1324                                        break;
1325                                if (ce_in_traverse_path(ce, &info))
1326                                        break;
1327                                if (unpack_index_entry(ce, o) < 0)
1328                                        goto return_failed;
1329                        }
1330                }
1331
1332                if (traverse_trees(len, t, &info) < 0)
1333                        goto return_failed;
1334        }
1335
1336        /* Any left-over entries in the index? */
1337        if (o->merge) {
1338                while (1) {
1339                        struct cache_entry *ce = next_cache_entry(o);
1340                        if (!ce)
1341                                break;
1342                        if (unpack_index_entry(ce, o) < 0)
1343                                goto return_failed;
1344                }
1345        }
1346        mark_all_ce_unused(o->src_index);
1347
1348        if (o->trivial_merges_only && o->nontrivial_merge) {
1349                ret = unpack_failed(o, "Merge requires file-level merging");
1350                goto done;
1351        }
1352
1353        if (!o->skip_sparse_checkout) {
1354                int empty_worktree = 1;
1355
1356                /*
1357                 * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1358                 * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1359                 * so apply_sparse_checkout() won't attempt to remove it from worktree
1360                 */
1361                mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1362
1363                ret = 0;
1364                for (i = 0; i < o->result.cache_nr; i++) {
1365                        struct cache_entry *ce = o->result.cache[i];
1366
1367                        /*
1368                         * Entries marked with CE_ADDED in merged_entry() do not have
1369                         * verify_absent() check (the check is effectively disabled
1370                         * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1371                         *
1372                         * Do the real check now because we have had
1373                         * correct CE_NEW_SKIP_WORKTREE
1374                         */
1375                        if (ce->ce_flags & CE_ADDED &&
1376                            verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1377                                if (!o->show_all_errors)
1378                                        goto return_failed;
1379                                ret = -1;
1380                        }
1381
1382                        if (apply_sparse_checkout(&o->result, ce, o)) {
1383                                if (!o->show_all_errors)
1384                                        goto return_failed;
1385                                ret = -1;
1386                        }
1387                        if (!ce_skip_worktree(ce))
1388                                empty_worktree = 0;
1389
1390                }
1391                if (ret < 0)
1392                        goto return_failed;
1393                /*
1394                 * Sparse checkout is meant to narrow down checkout area
1395                 * but it does not make sense to narrow down to empty working
1396                 * tree. This is usually a mistake in sparse checkout rules.
1397                 * Do not allow users to do that.
1398                 */
1399                if (o->result.cache_nr && empty_worktree) {
1400                        ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1401                        goto done;
1402                }
1403        }
1404
1405        o->src_index = NULL;
1406        ret = check_updates(o) ? (-2) : 0;
1407        if (o->dst_index) {
1408                if (!ret) {
1409                        if (!o->result.cache_tree)
1410                                o->result.cache_tree = cache_tree();
1411                        if (!cache_tree_fully_valid(o->result.cache_tree))
1412                                cache_tree_update(&o->result,
1413                                                  WRITE_TREE_SILENT |
1414                                                  WRITE_TREE_REPAIR);
1415                }
1416                move_index_extensions(&o->result, o->dst_index);
1417                discard_index(o->dst_index);
1418                *o->dst_index = o->result;
1419        } else {
1420                discard_index(&o->result);
1421        }
1422
1423done:
1424        clear_exclude_list(&el);
1425        return ret;
1426
1427return_failed:
1428        if (o->show_all_errors)
1429                display_error_msgs(o);
1430        mark_all_ce_unused(o->src_index);
1431        ret = unpack_failed(o, NULL);
1432        if (o->exiting_early)
1433                ret = 0;
1434        goto done;
1435}
1436
1437/* Here come the merge functions */
1438
1439static int reject_merge(const struct cache_entry *ce,
1440                        struct unpack_trees_options *o)
1441{
1442        return o->gently ? -1 :
1443                add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1444}
1445
1446static int same(const struct cache_entry *a, const struct cache_entry *b)
1447{
1448        if (!!a != !!b)
1449                return 0;
1450        if (!a && !b)
1451                return 1;
1452        if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1453                return 0;
1454        return a->ce_mode == b->ce_mode &&
1455               !oidcmp(&a->oid, &b->oid);
1456}
1457
1458
1459/*
1460 * When a CE gets turned into an unmerged entry, we
1461 * want it to be up-to-date
1462 */
1463static int verify_uptodate_1(const struct cache_entry *ce,
1464                             struct unpack_trees_options *o,
1465                             enum unpack_trees_error_types error_type)
1466{
1467        struct stat st;
1468
1469        if (o->index_only)
1470                return 0;
1471
1472        /*
1473         * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1474         * if this entry is truly up-to-date because this file may be
1475         * overwritten.
1476         */
1477        if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1478                ; /* keep checking */
1479        else if (o->reset || ce_uptodate(ce))
1480                return 0;
1481
1482        if (!lstat(ce->name, &st)) {
1483                int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1484                unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1485
1486                if (submodule_from_ce(ce)) {
1487                        int r = check_submodule_move_head(ce,
1488                                "HEAD", oid_to_hex(&ce->oid), o);
1489                        if (r)
1490                                return o->gently ? -1 :
1491                                        add_rejected_path(o, error_type, ce->name);
1492                        return 0;
1493                }
1494
1495                if (!changed)
1496                        return 0;
1497                /*
1498                 * Historic default policy was to allow submodule to be out
1499                 * of sync wrt the superproject index. If the submodule was
1500                 * not considered interesting above, we don't care here.
1501                 */
1502                if (S_ISGITLINK(ce->ce_mode))
1503                        return 0;
1504
1505                errno = 0;
1506        }
1507        if (errno == ENOENT)
1508                return 0;
1509        return o->gently ? -1 :
1510                add_rejected_path(o, error_type, ce->name);
1511}
1512
1513static int verify_uptodate(const struct cache_entry *ce,
1514                           struct unpack_trees_options *o)
1515{
1516        if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1517                return 0;
1518        return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1519}
1520
1521static int verify_uptodate_sparse(const struct cache_entry *ce,
1522                                  struct unpack_trees_options *o)
1523{
1524        return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1525}
1526
1527static void invalidate_ce_path(const struct cache_entry *ce,
1528                               struct unpack_trees_options *o)
1529{
1530        if (!ce)
1531                return;
1532        cache_tree_invalidate_path(o->src_index, ce->name);
1533        untracked_cache_invalidate_path(o->src_index, ce->name, 1);
1534}
1535
1536/*
1537 * Check that checking out ce->sha1 in subdir ce->name is not
1538 * going to overwrite any working files.
1539 *
1540 * Currently, git does not checkout subprojects during a superproject
1541 * checkout, so it is not going to overwrite anything.
1542 */
1543static int verify_clean_submodule(const char *old_sha1,
1544                                  const struct cache_entry *ce,
1545                                  enum unpack_trees_error_types error_type,
1546                                  struct unpack_trees_options *o)
1547{
1548        if (!submodule_from_ce(ce))
1549                return 0;
1550
1551        return check_submodule_move_head(ce, old_sha1,
1552                                         oid_to_hex(&ce->oid), o);
1553}
1554
1555static int verify_clean_subdirectory(const struct cache_entry *ce,
1556                                     enum unpack_trees_error_types error_type,
1557                                     struct unpack_trees_options *o)
1558{
1559        /*
1560         * we are about to extract "ce->name"; we would not want to lose
1561         * anything in the existing directory there.
1562         */
1563        int namelen;
1564        int i;
1565        struct dir_struct d;
1566        char *pathbuf;
1567        int cnt = 0;
1568
1569        if (S_ISGITLINK(ce->ce_mode)) {
1570                struct object_id oid;
1571                int sub_head = resolve_gitlink_ref(ce->name, "HEAD", &oid);
1572                /*
1573                 * If we are not going to update the submodule, then
1574                 * we don't care.
1575                 */
1576                if (!sub_head && !oidcmp(&oid, &ce->oid))
1577                        return 0;
1578                return verify_clean_submodule(sub_head ? NULL : oid_to_hex(&oid),
1579                                              ce, error_type, o);
1580        }
1581
1582        /*
1583         * First let's make sure we do not have a local modification
1584         * in that directory.
1585         */
1586        namelen = ce_namelen(ce);
1587        for (i = locate_in_src_index(ce, o);
1588             i < o->src_index->cache_nr;
1589             i++) {
1590                struct cache_entry *ce2 = o->src_index->cache[i];
1591                int len = ce_namelen(ce2);
1592                if (len < namelen ||
1593                    strncmp(ce->name, ce2->name, namelen) ||
1594                    ce2->name[namelen] != '/')
1595                        break;
1596                /*
1597                 * ce2->name is an entry in the subdirectory to be
1598                 * removed.
1599                 */
1600                if (!ce_stage(ce2)) {
1601                        if (verify_uptodate(ce2, o))
1602                                return -1;
1603                        add_entry(o, ce2, CE_REMOVE, 0);
1604                        mark_ce_used(ce2, o);
1605                }
1606                cnt++;
1607        }
1608
1609        /*
1610         * Then we need to make sure that we do not lose a locally
1611         * present file that is not ignored.
1612         */
1613        pathbuf = xstrfmt("%.*s/", namelen, ce->name);
1614
1615        memset(&d, 0, sizeof(d));
1616        if (o->dir)
1617                d.exclude_per_dir = o->dir->exclude_per_dir;
1618        i = read_directory(&d, &the_index, pathbuf, namelen+1, NULL);
1619        if (i)
1620                return o->gently ? -1 :
1621                        add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1622        free(pathbuf);
1623        return cnt;
1624}
1625
1626/*
1627 * This gets called when there was no index entry for the tree entry 'dst',
1628 * but we found a file in the working tree that 'lstat()' said was fine,
1629 * and we're on a case-insensitive filesystem.
1630 *
1631 * See if we can find a case-insensitive match in the index that also
1632 * matches the stat information, and assume it's that other file!
1633 */
1634static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1635{
1636        const struct cache_entry *src;
1637
1638        src = index_file_exists(o->src_index, name, len, 1);
1639        return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1640}
1641
1642static int check_ok_to_remove(const char *name, int len, int dtype,
1643                              const struct cache_entry *ce, struct stat *st,
1644                              enum unpack_trees_error_types error_type,
1645                              struct unpack_trees_options *o)
1646{
1647        const struct cache_entry *result;
1648
1649        /*
1650         * It may be that the 'lstat()' succeeded even though
1651         * target 'ce' was absent, because there is an old
1652         * entry that is different only in case..
1653         *
1654         * Ignore that lstat() if it matches.
1655         */
1656        if (ignore_case && icase_exists(o, name, len, st))
1657                return 0;
1658
1659        if (o->dir &&
1660            is_excluded(o->dir, &the_index, name, &dtype))
1661                /*
1662                 * ce->name is explicitly excluded, so it is Ok to
1663                 * overwrite it.
1664                 */
1665                return 0;
1666        if (S_ISDIR(st->st_mode)) {
1667                /*
1668                 * We are checking out path "foo" and
1669                 * found "foo/." in the working tree.
1670                 * This is tricky -- if we have modified
1671                 * files that are in "foo/" we would lose
1672                 * them.
1673                 */
1674                if (verify_clean_subdirectory(ce, error_type, o) < 0)
1675                        return -1;
1676                return 0;
1677        }
1678
1679        /*
1680         * The previous round may already have decided to
1681         * delete this path, which is in a subdirectory that
1682         * is being replaced with a blob.
1683         */
1684        result = index_file_exists(&o->result, name, len, 0);
1685        if (result) {
1686                if (result->ce_flags & CE_REMOVE)
1687                        return 0;
1688        }
1689
1690        return o->gently ? -1 :
1691                add_rejected_path(o, error_type, name);
1692}
1693
1694/*
1695 * We do not want to remove or overwrite a working tree file that
1696 * is not tracked, unless it is ignored.
1697 */
1698static int verify_absent_1(const struct cache_entry *ce,
1699                           enum unpack_trees_error_types error_type,
1700                           struct unpack_trees_options *o)
1701{
1702        int len;
1703        struct stat st;
1704
1705        if (o->index_only || o->reset || !o->update)
1706                return 0;
1707
1708        len = check_leading_path(ce->name, ce_namelen(ce));
1709        if (!len)
1710                return 0;
1711        else if (len > 0) {
1712                char *path;
1713                int ret;
1714
1715                path = xmemdupz(ce->name, len);
1716                if (lstat(path, &st))
1717                        ret = error_errno("cannot stat '%s'", path);
1718                else {
1719                        if (submodule_from_ce(ce))
1720                                ret = check_submodule_move_head(ce,
1721                                                                oid_to_hex(&ce->oid),
1722                                                                NULL, o);
1723                        else
1724                                ret = check_ok_to_remove(path, len, DT_UNKNOWN, NULL,
1725                                                         &st, error_type, o);
1726                }
1727                free(path);
1728                return ret;
1729        } else if (lstat(ce->name, &st)) {
1730                if (errno != ENOENT)
1731                        return error_errno("cannot stat '%s'", ce->name);
1732                return 0;
1733        } else {
1734                if (submodule_from_ce(ce))
1735                        return check_submodule_move_head(ce, oid_to_hex(&ce->oid),
1736                                                         NULL, o);
1737
1738                return check_ok_to_remove(ce->name, ce_namelen(ce),
1739                                          ce_to_dtype(ce), ce, &st,
1740                                          error_type, o);
1741        }
1742}
1743
1744static int verify_absent(const struct cache_entry *ce,
1745                         enum unpack_trees_error_types error_type,
1746                         struct unpack_trees_options *o)
1747{
1748        if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1749                return 0;
1750        return verify_absent_1(ce, error_type, o);
1751}
1752
1753static int verify_absent_sparse(const struct cache_entry *ce,
1754                                enum unpack_trees_error_types error_type,
1755                                struct unpack_trees_options *o)
1756{
1757        enum unpack_trees_error_types orphaned_error = error_type;
1758        if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1759                orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1760
1761        return verify_absent_1(ce, orphaned_error, o);
1762}
1763
1764static int merged_entry(const struct cache_entry *ce,
1765                        const struct cache_entry *old,
1766                        struct unpack_trees_options *o)
1767{
1768        int update = CE_UPDATE;
1769        struct cache_entry *merge = dup_entry(ce);
1770
1771        if (!old) {
1772                /*
1773                 * New index entries. In sparse checkout, the following
1774                 * verify_absent() will be delayed until after
1775                 * traverse_trees() finishes in unpack_trees(), then:
1776                 *
1777                 *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1778                 *  - verify_absent() be called again, this time with
1779                 *    correct CE_NEW_SKIP_WORKTREE
1780                 *
1781                 * verify_absent() call here does nothing in sparse
1782                 * checkout (i.e. o->skip_sparse_checkout == 0)
1783                 */
1784                update |= CE_ADDED;
1785                merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1786
1787                if (verify_absent(merge,
1788                                  ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1789                        free(merge);
1790                        return -1;
1791                }
1792                invalidate_ce_path(merge, o);
1793
1794                if (submodule_from_ce(ce)) {
1795                        int ret = check_submodule_move_head(ce, NULL,
1796                                                            oid_to_hex(&ce->oid),
1797                                                            o);
1798                        if (ret)
1799                                return ret;
1800                }
1801
1802        } else if (!(old->ce_flags & CE_CONFLICTED)) {
1803                /*
1804                 * See if we can re-use the old CE directly?
1805                 * That way we get the uptodate stat info.
1806                 *
1807                 * This also removes the UPDATE flag on a match; otherwise
1808                 * we will end up overwriting local changes in the work tree.
1809                 */
1810                if (same(old, merge)) {
1811                        copy_cache_entry(merge, old);
1812                        update = 0;
1813                } else {
1814                        if (verify_uptodate(old, o)) {
1815                                free(merge);
1816                                return -1;
1817                        }
1818                        /* Migrate old flags over */
1819                        update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1820                        invalidate_ce_path(old, o);
1821                }
1822
1823                if (submodule_from_ce(ce)) {
1824                        int ret = check_submodule_move_head(ce, oid_to_hex(&old->oid),
1825                                                            oid_to_hex(&ce->oid),
1826                                                            o);
1827                        if (ret)
1828                                return ret;
1829                }
1830        } else {
1831                /*
1832                 * Previously unmerged entry left as an existence
1833                 * marker by read_index_unmerged();
1834                 */
1835                invalidate_ce_path(old, o);
1836        }
1837
1838        do_add_entry(o, merge, update, CE_STAGEMASK);
1839        return 1;
1840}
1841
1842static int deleted_entry(const struct cache_entry *ce,
1843                         const struct cache_entry *old,
1844                         struct unpack_trees_options *o)
1845{
1846        /* Did it exist in the index? */
1847        if (!old) {
1848                if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1849                        return -1;
1850                return 0;
1851        }
1852        if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1853                return -1;
1854        add_entry(o, ce, CE_REMOVE, 0);
1855        invalidate_ce_path(ce, o);
1856        return 1;
1857}
1858
1859static int keep_entry(const struct cache_entry *ce,
1860                      struct unpack_trees_options *o)
1861{
1862        add_entry(o, ce, 0, 0);
1863        return 1;
1864}
1865
1866#if DBRT_DEBUG
1867static void show_stage_entry(FILE *o,
1868                             const char *label, const struct cache_entry *ce)
1869{
1870        if (!ce)
1871                fprintf(o, "%s (missing)\n", label);
1872        else
1873                fprintf(o, "%s%06o %s %d\t%s\n",
1874                        label,
1875                        ce->ce_mode,
1876                        oid_to_hex(&ce->oid),
1877                        ce_stage(ce),
1878                        ce->name);
1879}
1880#endif
1881
1882int threeway_merge(const struct cache_entry * const *stages,
1883                   struct unpack_trees_options *o)
1884{
1885        const struct cache_entry *index;
1886        const struct cache_entry *head;
1887        const struct cache_entry *remote = stages[o->head_idx + 1];
1888        int count;
1889        int head_match = 0;
1890        int remote_match = 0;
1891
1892        int df_conflict_head = 0;
1893        int df_conflict_remote = 0;
1894
1895        int any_anc_missing = 0;
1896        int no_anc_exists = 1;
1897        int i;
1898
1899        for (i = 1; i < o->head_idx; i++) {
1900                if (!stages[i] || stages[i] == o->df_conflict_entry)
1901                        any_anc_missing = 1;
1902                else
1903                        no_anc_exists = 0;
1904        }
1905
1906        index = stages[0];
1907        head = stages[o->head_idx];
1908
1909        if (head == o->df_conflict_entry) {
1910                df_conflict_head = 1;
1911                head = NULL;
1912        }
1913
1914        if (remote == o->df_conflict_entry) {
1915                df_conflict_remote = 1;
1916                remote = NULL;
1917        }
1918
1919        /*
1920         * First, if there's a #16 situation, note that to prevent #13
1921         * and #14.
1922         */
1923        if (!same(remote, head)) {
1924                for (i = 1; i < o->head_idx; i++) {
1925                        if (same(stages[i], head)) {
1926                                head_match = i;
1927                        }
1928                        if (same(stages[i], remote)) {
1929                                remote_match = i;
1930                        }
1931                }
1932        }
1933
1934        /*
1935         * We start with cases where the index is allowed to match
1936         * something other than the head: #14(ALT) and #2ALT, where it
1937         * is permitted to match the result instead.
1938         */
1939        /* #14, #14ALT, #2ALT */
1940        if (remote && !df_conflict_head && head_match && !remote_match) {
1941                if (index && !same(index, remote) && !same(index, head))
1942                        return reject_merge(index, o);
1943                return merged_entry(remote, index, o);
1944        }
1945        /*
1946         * If we have an entry in the index cache, then we want to
1947         * make sure that it matches head.
1948         */
1949        if (index && !same(index, head))
1950                return reject_merge(index, o);
1951
1952        if (head) {
1953                /* #5ALT, #15 */
1954                if (same(head, remote))
1955                        return merged_entry(head, index, o);
1956                /* #13, #3ALT */
1957                if (!df_conflict_remote && remote_match && !head_match)
1958                        return merged_entry(head, index, o);
1959        }
1960
1961        /* #1 */
1962        if (!head && !remote && any_anc_missing)
1963                return 0;
1964
1965        /*
1966         * Under the "aggressive" rule, we resolve mostly trivial
1967         * cases that we historically had git-merge-one-file resolve.
1968         */
1969        if (o->aggressive) {
1970                int head_deleted = !head;
1971                int remote_deleted = !remote;
1972                const struct cache_entry *ce = NULL;
1973
1974                if (index)
1975                        ce = index;
1976                else if (head)
1977                        ce = head;
1978                else if (remote)
1979                        ce = remote;
1980                else {
1981                        for (i = 1; i < o->head_idx; i++) {
1982                                if (stages[i] && stages[i] != o->df_conflict_entry) {
1983                                        ce = stages[i];
1984                                        break;
1985                                }
1986                        }
1987                }
1988
1989                /*
1990                 * Deleted in both.
1991                 * Deleted in one and unchanged in the other.
1992                 */
1993                if ((head_deleted && remote_deleted) ||
1994                    (head_deleted && remote && remote_match) ||
1995                    (remote_deleted && head && head_match)) {
1996                        if (index)
1997                                return deleted_entry(index, index, o);
1998                        if (ce && !head_deleted) {
1999                                if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
2000                                        return -1;
2001                        }
2002                        return 0;
2003                }
2004                /*
2005                 * Added in both, identically.
2006                 */
2007                if (no_anc_exists && head && remote && same(head, remote))
2008                        return merged_entry(head, index, o);
2009
2010        }
2011
2012        /* Below are "no merge" cases, which require that the index be
2013         * up-to-date to avoid the files getting overwritten with
2014         * conflict resolution files.
2015         */
2016        if (index) {
2017                if (verify_uptodate(index, o))
2018                        return -1;
2019        }
2020
2021        o->nontrivial_merge = 1;
2022
2023        /* #2, #3, #4, #6, #7, #9, #10, #11. */
2024        count = 0;
2025        if (!head_match || !remote_match) {
2026                for (i = 1; i < o->head_idx; i++) {
2027                        if (stages[i] && stages[i] != o->df_conflict_entry) {
2028                                keep_entry(stages[i], o);
2029                                count++;
2030                                break;
2031                        }
2032                }
2033        }
2034#if DBRT_DEBUG
2035        else {
2036                fprintf(stderr, "read-tree: warning #16 detected\n");
2037                show_stage_entry(stderr, "head   ", stages[head_match]);
2038                show_stage_entry(stderr, "remote ", stages[remote_match]);
2039        }
2040#endif
2041        if (head) { count += keep_entry(head, o); }
2042        if (remote) { count += keep_entry(remote, o); }
2043        return count;
2044}
2045
2046/*
2047 * Two-way merge.
2048 *
2049 * The rule is to "carry forward" what is in the index without losing
2050 * information across a "fast-forward", favoring a successful merge
2051 * over a merge failure when it makes sense.  For details of the
2052 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
2053 *
2054 */
2055int twoway_merge(const struct cache_entry * const *src,
2056                 struct unpack_trees_options *o)
2057{
2058        const struct cache_entry *current = src[0];
2059        const struct cache_entry *oldtree = src[1];
2060        const struct cache_entry *newtree = src[2];
2061
2062        if (o->merge_size != 2)
2063                return error("Cannot do a twoway merge of %d trees",
2064                             o->merge_size);
2065
2066        if (oldtree == o->df_conflict_entry)
2067                oldtree = NULL;
2068        if (newtree == o->df_conflict_entry)
2069                newtree = NULL;
2070
2071        if (current) {
2072                if (current->ce_flags & CE_CONFLICTED) {
2073                        if (same(oldtree, newtree) || o->reset) {
2074                                if (!newtree)
2075                                        return deleted_entry(current, current, o);
2076                                else
2077                                        return merged_entry(newtree, current, o);
2078                        }
2079                        return reject_merge(current, o);
2080                } else if ((!oldtree && !newtree) || /* 4 and 5 */
2081                         (!oldtree && newtree &&
2082                          same(current, newtree)) || /* 6 and 7 */
2083                         (oldtree && newtree &&
2084                          same(oldtree, newtree)) || /* 14 and 15 */
2085                         (oldtree && newtree &&
2086                          !same(oldtree, newtree) && /* 18 and 19 */
2087                          same(current, newtree))) {
2088                        return keep_entry(current, o);
2089                } else if (oldtree && !newtree && same(current, oldtree)) {
2090                        /* 10 or 11 */
2091                        return deleted_entry(oldtree, current, o);
2092                } else if (oldtree && newtree &&
2093                         same(current, oldtree) && !same(current, newtree)) {
2094                        /* 20 or 21 */
2095                        return merged_entry(newtree, current, o);
2096                } else
2097                        return reject_merge(current, o);
2098        }
2099        else if (newtree) {
2100                if (oldtree && !o->initial_checkout) {
2101                        /*
2102                         * deletion of the path was staged;
2103                         */
2104                        if (same(oldtree, newtree))
2105                                return 1;
2106                        return reject_merge(oldtree, o);
2107                }
2108                return merged_entry(newtree, current, o);
2109        }
2110        return deleted_entry(oldtree, current, o);
2111}
2112
2113/*
2114 * Bind merge.
2115 *
2116 * Keep the index entries at stage0, collapse stage1 but make sure
2117 * stage0 does not have anything there.
2118 */
2119int bind_merge(const struct cache_entry * const *src,
2120               struct unpack_trees_options *o)
2121{
2122        const struct cache_entry *old = src[0];
2123        const struct cache_entry *a = src[1];
2124
2125        if (o->merge_size != 1)
2126                return error("Cannot do a bind merge of %d trees",
2127                             o->merge_size);
2128        if (a && old)
2129                return o->gently ? -1 :
2130                        error(ERRORMSG(o, ERROR_BIND_OVERLAP),
2131                              super_prefixed(a->name),
2132                              super_prefixed(old->name));
2133        if (!a)
2134                return keep_entry(old, o);
2135        else
2136                return merged_entry(a, NULL, o);
2137}
2138
2139/*
2140 * One-way merge.
2141 *
2142 * The rule is:
2143 * - take the stat information from stage0, take the data from stage1
2144 */
2145int oneway_merge(const struct cache_entry * const *src,
2146                 struct unpack_trees_options *o)
2147{
2148        const struct cache_entry *old = src[0];
2149        const struct cache_entry *a = src[1];
2150
2151        if (o->merge_size != 1)
2152                return error("Cannot do a oneway merge of %d trees",
2153                             o->merge_size);
2154
2155        if (!a || a == o->df_conflict_entry)
2156                return deleted_entry(old, old, o);
2157
2158        if (old && same(old, a)) {
2159                int update = 0;
2160                if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
2161                        struct stat st;
2162                        if (lstat(old->name, &st) ||
2163                            ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
2164                                update |= CE_UPDATE;
2165                }
2166                if (o->update && S_ISGITLINK(old->ce_mode) &&
2167                    should_update_submodules() && !verify_uptodate(old, o))
2168                        update |= CE_UPDATE;
2169                add_entry(o, old, update, 0);
2170                return 0;
2171        }
2172        return merged_entry(a, old, o);
2173}