unpack-trees.con commit khash: rename oid helper functions (e465e7c)
   1#include "cache.h"
   2#include "argv-array.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        argv_array_init(&opts->msgs_to_free);
 108
 109        if (!strcmp(cmd, "checkout"))
 110                msg = advice_commit_before_merge
 111                      ? _("Your local changes to the following files would be overwritten by checkout:\n%%s"
 112                          "Please commit your changes or stash them before you switch branches.")
 113                      : _("Your local changes to the following files would be overwritten by checkout:\n%%s");
 114        else if (!strcmp(cmd, "merge"))
 115                msg = advice_commit_before_merge
 116                      ? _("Your local changes to the following files would be overwritten by merge:\n%%s"
 117                          "Please commit your changes or stash them before you merge.")
 118                      : _("Your local changes to the following files would be overwritten by merge:\n%%s");
 119        else
 120                msg = advice_commit_before_merge
 121                      ? _("Your local changes to the following files would be overwritten by %s:\n%%s"
 122                          "Please commit your changes or stash them before you %s.")
 123                      : _("Your local changes to the following files would be overwritten by %s:\n%%s");
 124        msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
 125                argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
 126
 127        msgs[ERROR_NOT_UPTODATE_DIR] =
 128                _("Updating the following directories would lose untracked files in them:\n%s");
 129
 130        if (!strcmp(cmd, "checkout"))
 131                msg = advice_commit_before_merge
 132                      ? _("The following untracked working tree files would be removed by checkout:\n%%s"
 133                          "Please move or remove them before you switch branches.")
 134                      : _("The following untracked working tree files would be removed by checkout:\n%%s");
 135        else if (!strcmp(cmd, "merge"))
 136                msg = advice_commit_before_merge
 137                      ? _("The following untracked working tree files would be removed by merge:\n%%s"
 138                          "Please move or remove them before you merge.")
 139                      : _("The following untracked working tree files would be removed by merge:\n%%s");
 140        else
 141                msg = advice_commit_before_merge
 142                      ? _("The following untracked working tree files would be removed by %s:\n%%s"
 143                          "Please move or remove them before you %s.")
 144                      : _("The following untracked working tree files would be removed by %s:\n%%s");
 145        msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] =
 146                argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
 147
 148        if (!strcmp(cmd, "checkout"))
 149                msg = advice_commit_before_merge
 150                      ? _("The following untracked working tree files would be overwritten by checkout:\n%%s"
 151                          "Please move or remove them before you switch branches.")
 152                      : _("The following untracked working tree files would be overwritten by checkout:\n%%s");
 153        else if (!strcmp(cmd, "merge"))
 154                msg = advice_commit_before_merge
 155                      ? _("The following untracked working tree files would be overwritten by merge:\n%%s"
 156                          "Please move or remove them before you merge.")
 157                      : _("The following untracked working tree files would be overwritten by merge:\n%%s");
 158        else
 159                msg = advice_commit_before_merge
 160                      ? _("The following untracked working tree files would be overwritten by %s:\n%%s"
 161                          "Please move or remove them before you %s.")
 162                      : _("The following untracked working tree files would be overwritten by %s:\n%%s");
 163        msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] =
 164                argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
 165
 166        /*
 167         * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
 168         * cannot easily display it as a list.
 169         */
 170        msgs[ERROR_BIND_OVERLAP] = _("Entry '%s' overlaps with '%s'.  Cannot bind.");
 171
 172        msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
 173                _("Cannot update sparse checkout: the following entries are not up to date:\n%s");
 174        msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
 175                _("The following working tree files would be overwritten by sparse checkout update:\n%s");
 176        msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
 177                _("The following working tree files would be removed by sparse checkout update:\n%s");
 178        msgs[ERROR_WOULD_LOSE_SUBMODULE] =
 179                _("Cannot update submodule:\n%s");
 180
 181        opts->show_all_errors = 1;
 182        /* rejected paths may not have a static buffer */
 183        for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
 184                opts->unpack_rejects[i].strdup_strings = 1;
 185}
 186
 187void clear_unpack_trees_porcelain(struct unpack_trees_options *opts)
 188{
 189        argv_array_clear(&opts->msgs_to_free);
 190        memset(opts->msgs, 0, sizeof(opts->msgs));
 191}
 192
 193static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
 194                         unsigned int set, unsigned int clear)
 195{
 196        clear |= CE_HASHED;
 197
 198        if (set & CE_REMOVE)
 199                set |= CE_WT_REMOVE;
 200
 201        ce->ce_flags = (ce->ce_flags & ~clear) | set;
 202        return add_index_entry(&o->result, ce,
 203                               ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 204}
 205
 206static void add_entry(struct unpack_trees_options *o,
 207                      const struct cache_entry *ce,
 208                      unsigned int set, unsigned int clear)
 209{
 210        do_add_entry(o, dup_cache_entry(ce, &o->result), set, clear);
 211}
 212
 213/*
 214 * add error messages on path <path>
 215 * corresponding to the type <e> with the message <msg>
 216 * indicating if it should be display in porcelain or not
 217 */
 218static int add_rejected_path(struct unpack_trees_options *o,
 219                             enum unpack_trees_error_types e,
 220                             const char *path)
 221{
 222        if (o->quiet)
 223                return -1;
 224
 225        if (!o->show_all_errors)
 226                return error(ERRORMSG(o, e), super_prefixed(path));
 227
 228        /*
 229         * Otherwise, insert in a list for future display by
 230         * display_error_msgs()
 231         */
 232        string_list_append(&o->unpack_rejects[e], path);
 233        return -1;
 234}
 235
 236/*
 237 * display all the error messages stored in a nice way
 238 */
 239static void display_error_msgs(struct unpack_trees_options *o)
 240{
 241        int e, i;
 242        int something_displayed = 0;
 243        for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
 244                struct string_list *rejects = &o->unpack_rejects[e];
 245                if (rejects->nr > 0) {
 246                        struct strbuf path = STRBUF_INIT;
 247                        something_displayed = 1;
 248                        for (i = 0; i < rejects->nr; i++)
 249                                strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
 250                        error(ERRORMSG(o, e), super_prefixed(path.buf));
 251                        strbuf_release(&path);
 252                }
 253                string_list_clear(rejects, 0);
 254        }
 255        if (something_displayed)
 256                fprintf(stderr, _("Aborting\n"));
 257}
 258
 259static int check_submodule_move_head(const struct cache_entry *ce,
 260                                     const char *old_id,
 261                                     const char *new_id,
 262                                     struct unpack_trees_options *o)
 263{
 264        unsigned flags = SUBMODULE_MOVE_HEAD_DRY_RUN;
 265        const struct submodule *sub = submodule_from_ce(ce);
 266
 267        if (!sub)
 268                return 0;
 269
 270        if (o->reset)
 271                flags |= SUBMODULE_MOVE_HEAD_FORCE;
 272
 273        if (submodule_move_head(ce->name, old_id, new_id, flags))
 274                return add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
 275        return 0;
 276}
 277
 278/*
 279 * Preform the loading of the repository's gitmodules file.  This function is
 280 * used by 'check_update()' to perform loading of the gitmodules file in two
 281 * differnt situations:
 282 * (1) before removing entries from the working tree if the gitmodules file has
 283 *     been marked for removal.  This situation is specified by 'state' == NULL.
 284 * (2) before checking out entries to the working tree if the gitmodules file
 285 *     has been marked for update.  This situation is specified by 'state' != NULL.
 286 */
 287static void load_gitmodules_file(struct index_state *index,
 288                                 struct checkout *state)
 289{
 290        int pos = index_name_pos(index, GITMODULES_FILE, strlen(GITMODULES_FILE));
 291
 292        if (pos >= 0) {
 293                struct cache_entry *ce = index->cache[pos];
 294                if (!state && ce->ce_flags & CE_WT_REMOVE) {
 295                        repo_read_gitmodules(the_repository);
 296                } else if (state && (ce->ce_flags & CE_UPDATE)) {
 297                        submodule_free(the_repository);
 298                        checkout_entry(ce, state, NULL, NULL);
 299                        repo_read_gitmodules(the_repository);
 300                }
 301        }
 302}
 303
 304static struct progress *get_progress(struct unpack_trees_options *o)
 305{
 306        unsigned cnt = 0, total = 0;
 307        struct index_state *index = &o->result;
 308
 309        if (!o->update || !o->verbose_update)
 310                return NULL;
 311
 312        for (; cnt < index->cache_nr; cnt++) {
 313                const struct cache_entry *ce = index->cache[cnt];
 314                if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
 315                        total++;
 316        }
 317
 318        return start_delayed_progress(_("Checking out files"), total);
 319}
 320
 321static void setup_collided_checkout_detection(struct checkout *state,
 322                                              struct index_state *index)
 323{
 324        int i;
 325
 326        state->clone = 1;
 327        for (i = 0; i < index->cache_nr; i++)
 328                index->cache[i]->ce_flags &= ~CE_MATCHED;
 329}
 330
 331static void report_collided_checkout(struct index_state *index)
 332{
 333        struct string_list list = STRING_LIST_INIT_NODUP;
 334        int i;
 335
 336        for (i = 0; i < index->cache_nr; i++) {
 337                struct cache_entry *ce = index->cache[i];
 338
 339                if (!(ce->ce_flags & CE_MATCHED))
 340                        continue;
 341
 342                string_list_append(&list, ce->name);
 343                ce->ce_flags &= ~CE_MATCHED;
 344        }
 345
 346        list.cmp = fspathcmp;
 347        string_list_sort(&list);
 348
 349        if (list.nr) {
 350                warning(_("the following paths have collided (e.g. case-sensitive paths\n"
 351                          "on a case-insensitive filesystem) and only one from the same\n"
 352                          "colliding group is in the working tree:\n"));
 353
 354                for (i = 0; i < list.nr; i++)
 355                        fprintf(stderr, "  '%s'\n", list.items[i].string);
 356        }
 357
 358        string_list_clear(&list, 0);
 359}
 360
 361static int check_updates(struct unpack_trees_options *o)
 362{
 363        unsigned cnt = 0;
 364        int errs = 0;
 365        struct progress *progress;
 366        struct index_state *index = &o->result;
 367        struct checkout state = CHECKOUT_INIT;
 368        int i;
 369
 370        trace_performance_enter();
 371        state.force = 1;
 372        state.quiet = 1;
 373        state.refresh_cache = 1;
 374        state.istate = index;
 375
 376        if (o->clone)
 377                setup_collided_checkout_detection(&state, index);
 378
 379        progress = get_progress(o);
 380
 381        if (o->update)
 382                git_attr_set_direction(GIT_ATTR_CHECKOUT);
 383
 384        if (should_update_submodules() && o->update && !o->dry_run)
 385                load_gitmodules_file(index, NULL);
 386
 387        for (i = 0; i < index->cache_nr; i++) {
 388                const struct cache_entry *ce = index->cache[i];
 389
 390                if (ce->ce_flags & CE_WT_REMOVE) {
 391                        display_progress(progress, ++cnt);
 392                        if (o->update && !o->dry_run)
 393                                unlink_entry(ce);
 394                }
 395        }
 396        remove_marked_cache_entries(index, 0);
 397        remove_scheduled_dirs();
 398
 399        if (should_update_submodules() && o->update && !o->dry_run)
 400                load_gitmodules_file(index, &state);
 401
 402        enable_delayed_checkout(&state);
 403        if (repository_format_partial_clone && o->update && !o->dry_run) {
 404                /*
 405                 * Prefetch the objects that are to be checked out in the loop
 406                 * below.
 407                 */
 408                struct oid_array to_fetch = OID_ARRAY_INIT;
 409                for (i = 0; i < index->cache_nr; i++) {
 410                        struct cache_entry *ce = index->cache[i];
 411
 412                        if (!(ce->ce_flags & CE_UPDATE) ||
 413                            S_ISGITLINK(ce->ce_mode))
 414                                continue;
 415                        if (!oid_object_info_extended(the_repository, &ce->oid,
 416                                                      NULL,
 417                                                      OBJECT_INFO_FOR_PREFETCH))
 418                                continue;
 419                        oid_array_append(&to_fetch, &ce->oid);
 420                }
 421                if (to_fetch.nr)
 422                        fetch_objects(repository_format_partial_clone,
 423                                      to_fetch.oid, to_fetch.nr);
 424                oid_array_clear(&to_fetch);
 425        }
 426        for (i = 0; i < index->cache_nr; i++) {
 427                struct cache_entry *ce = index->cache[i];
 428
 429                if (ce->ce_flags & CE_UPDATE) {
 430                        if (ce->ce_flags & CE_WT_REMOVE)
 431                                BUG("both update and delete flags are set on %s",
 432                                    ce->name);
 433                        display_progress(progress, ++cnt);
 434                        ce->ce_flags &= ~CE_UPDATE;
 435                        if (o->update && !o->dry_run) {
 436                                errs |= checkout_entry(ce, &state, NULL, NULL);
 437                        }
 438                }
 439        }
 440        stop_progress(&progress);
 441        errs |= finish_delayed_checkout(&state, NULL);
 442        if (o->update)
 443                git_attr_set_direction(GIT_ATTR_CHECKIN);
 444
 445        if (o->clone)
 446                report_collided_checkout(index);
 447
 448        trace_performance_leave("check_updates");
 449        return errs != 0;
 450}
 451
 452static int verify_uptodate_sparse(const struct cache_entry *ce,
 453                                  struct unpack_trees_options *o);
 454static int verify_absent_sparse(const struct cache_entry *ce,
 455                                enum unpack_trees_error_types,
 456                                struct unpack_trees_options *o);
 457
 458static int apply_sparse_checkout(struct index_state *istate,
 459                                 struct cache_entry *ce,
 460                                 struct unpack_trees_options *o)
 461{
 462        int was_skip_worktree = ce_skip_worktree(ce);
 463
 464        if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
 465                ce->ce_flags |= CE_SKIP_WORKTREE;
 466        else
 467                ce->ce_flags &= ~CE_SKIP_WORKTREE;
 468        if (was_skip_worktree != ce_skip_worktree(ce)) {
 469                ce->ce_flags |= CE_UPDATE_IN_BASE;
 470                mark_fsmonitor_invalid(istate, ce);
 471                istate->cache_changed |= CE_ENTRY_CHANGED;
 472        }
 473
 474        /*
 475         * if (!was_skip_worktree && !ce_skip_worktree()) {
 476         *      This is perfectly normal. Move on;
 477         * }
 478         */
 479
 480        /*
 481         * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
 482         * area as a result of ce_skip_worktree() shortcuts in
 483         * verify_absent() and verify_uptodate().
 484         * Make sure they don't modify worktree if they are already
 485         * outside checkout area
 486         */
 487        if (was_skip_worktree && ce_skip_worktree(ce)) {
 488                ce->ce_flags &= ~CE_UPDATE;
 489
 490                /*
 491                 * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
 492                 * on to get that file removed from both index and worktree.
 493                 * If that file is already outside worktree area, don't
 494                 * bother remove it.
 495                 */
 496                if (ce->ce_flags & CE_REMOVE)
 497                        ce->ce_flags &= ~CE_WT_REMOVE;
 498        }
 499
 500        if (!was_skip_worktree && ce_skip_worktree(ce)) {
 501                /*
 502                 * If CE_UPDATE is set, verify_uptodate() must be called already
 503                 * also stat info may have lost after merged_entry() so calling
 504                 * verify_uptodate() again may fail
 505                 */
 506                if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
 507                        return -1;
 508                ce->ce_flags |= CE_WT_REMOVE;
 509                ce->ce_flags &= ~CE_UPDATE;
 510        }
 511        if (was_skip_worktree && !ce_skip_worktree(ce)) {
 512                if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
 513                        return -1;
 514                ce->ce_flags |= CE_UPDATE;
 515        }
 516        return 0;
 517}
 518
 519static inline int call_unpack_fn(const struct cache_entry * const *src,
 520                                 struct unpack_trees_options *o)
 521{
 522        int ret = o->fn(src, o);
 523        if (ret > 0)
 524                ret = 0;
 525        return ret;
 526}
 527
 528static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
 529{
 530        ce->ce_flags |= CE_UNPACKED;
 531
 532        if (o->cache_bottom < o->src_index->cache_nr &&
 533            o->src_index->cache[o->cache_bottom] == ce) {
 534                int bottom = o->cache_bottom;
 535                while (bottom < o->src_index->cache_nr &&
 536                       o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
 537                        bottom++;
 538                o->cache_bottom = bottom;
 539        }
 540}
 541
 542static void mark_all_ce_unused(struct index_state *index)
 543{
 544        int i;
 545        for (i = 0; i < index->cache_nr; i++)
 546                index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
 547}
 548
 549static int locate_in_src_index(const struct cache_entry *ce,
 550                               struct unpack_trees_options *o)
 551{
 552        struct index_state *index = o->src_index;
 553        int len = ce_namelen(ce);
 554        int pos = index_name_pos(index, ce->name, len);
 555        if (pos < 0)
 556                pos = -1 - pos;
 557        return pos;
 558}
 559
 560/*
 561 * We call unpack_index_entry() with an unmerged cache entry
 562 * only in diff-index, and it wants a single callback.  Skip
 563 * the other unmerged entry with the same name.
 564 */
 565static void mark_ce_used_same_name(struct cache_entry *ce,
 566                                   struct unpack_trees_options *o)
 567{
 568        struct index_state *index = o->src_index;
 569        int len = ce_namelen(ce);
 570        int pos;
 571
 572        for (pos = locate_in_src_index(ce, o); 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                mark_ce_used(next, o);
 578        }
 579}
 580
 581static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
 582{
 583        const struct index_state *index = o->src_index;
 584        int pos = o->cache_bottom;
 585
 586        while (pos < index->cache_nr) {
 587                struct cache_entry *ce = index->cache[pos];
 588                if (!(ce->ce_flags & CE_UNPACKED))
 589                        return ce;
 590                pos++;
 591        }
 592        return NULL;
 593}
 594
 595static void add_same_unmerged(const struct cache_entry *ce,
 596                              struct unpack_trees_options *o)
 597{
 598        struct index_state *index = o->src_index;
 599        int len = ce_namelen(ce);
 600        int pos = index_name_pos(index, ce->name, len);
 601
 602        if (0 <= pos)
 603                die("programming error in a caller of mark_ce_used_same_name");
 604        for (pos = -pos - 1; pos < index->cache_nr; pos++) {
 605                struct cache_entry *next = index->cache[pos];
 606                if (len != ce_namelen(next) ||
 607                    memcmp(ce->name, next->name, len))
 608                        break;
 609                add_entry(o, next, 0, 0);
 610                mark_ce_used(next, o);
 611        }
 612}
 613
 614static int unpack_index_entry(struct cache_entry *ce,
 615                              struct unpack_trees_options *o)
 616{
 617        const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 618        int ret;
 619
 620        src[0] = ce;
 621
 622        mark_ce_used(ce, o);
 623        if (ce_stage(ce)) {
 624                if (o->skip_unmerged) {
 625                        add_entry(o, ce, 0, 0);
 626                        return 0;
 627                }
 628        }
 629        ret = call_unpack_fn(src, o);
 630        if (ce_stage(ce))
 631                mark_ce_used_same_name(ce, o);
 632        return ret;
 633}
 634
 635static int find_cache_pos(struct traverse_info *, const struct name_entry *);
 636
 637static void restore_cache_bottom(struct traverse_info *info, int bottom)
 638{
 639        struct unpack_trees_options *o = info->data;
 640
 641        if (o->diff_index_cached)
 642                return;
 643        o->cache_bottom = bottom;
 644}
 645
 646static int switch_cache_bottom(struct traverse_info *info)
 647{
 648        struct unpack_trees_options *o = info->data;
 649        int ret, pos;
 650
 651        if (o->diff_index_cached)
 652                return 0;
 653        ret = o->cache_bottom;
 654        pos = find_cache_pos(info->prev, &info->name);
 655
 656        if (pos < -1)
 657                o->cache_bottom = -2 - pos;
 658        else if (pos < 0)
 659                o->cache_bottom = o->src_index->cache_nr;
 660        return ret;
 661}
 662
 663static inline int are_same_oid(struct name_entry *name_j, struct name_entry *name_k)
 664{
 665        return !is_null_oid(&name_j->oid) && !is_null_oid(&name_k->oid) && oideq(&name_j->oid, &name_k->oid);
 666}
 667
 668static int all_trees_same_as_cache_tree(int n, unsigned long dirmask,
 669                                        struct name_entry *names,
 670                                        struct traverse_info *info)
 671{
 672        struct unpack_trees_options *o = info->data;
 673        int i;
 674
 675        if (!o->merge || dirmask != ((1 << n) - 1))
 676                return 0;
 677
 678        for (i = 1; i < n; i++)
 679                if (!are_same_oid(names, names + i))
 680                        return 0;
 681
 682        return cache_tree_matches_traversal(o->src_index->cache_tree, names, info);
 683}
 684
 685static int index_pos_by_traverse_info(struct name_entry *names,
 686                                      struct traverse_info *info)
 687{
 688        struct unpack_trees_options *o = info->data;
 689        int len = traverse_path_len(info, names);
 690        char *name = xmalloc(len + 1 /* slash */ + 1 /* NUL */);
 691        int pos;
 692
 693        make_traverse_path(name, info, names);
 694        name[len++] = '/';
 695        name[len] = '\0';
 696        pos = index_name_pos(o->src_index, name, len);
 697        if (pos >= 0)
 698                BUG("This is a directory and should not exist in index");
 699        pos = -pos - 1;
 700        if (!starts_with(o->src_index->cache[pos]->name, name) ||
 701            (pos > 0 && starts_with(o->src_index->cache[pos-1]->name, name)))
 702                BUG("pos must point at the first entry in this directory");
 703        free(name);
 704        return pos;
 705}
 706
 707/*
 708 * Fast path if we detect that all trees are the same as cache-tree at this
 709 * path. We'll walk these trees in an iterative loop using cache-tree/index
 710 * instead of ODB since we already know what these trees contain.
 711 */
 712static int traverse_by_cache_tree(int pos, int nr_entries, int nr_names,
 713                                  struct traverse_info *info)
 714{
 715        struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 716        struct unpack_trees_options *o = info->data;
 717        struct cache_entry *tree_ce = NULL;
 718        int ce_len = 0;
 719        int i, d;
 720
 721        if (!o->merge)
 722                BUG("We need cache-tree to do this optimization");
 723
 724        /*
 725         * Do what unpack_callback() and unpack_nondirectories() normally
 726         * do. But we walk all paths in an iterative loop instead.
 727         *
 728         * D/F conflicts and higher stage entries are not a concern
 729         * because cache-tree would be invalidated and we would never
 730         * get here in the first place.
 731         */
 732        for (i = 0; i < nr_entries; i++) {
 733                int new_ce_len, len, rc;
 734
 735                src[0] = o->src_index->cache[pos + i];
 736
 737                len = ce_namelen(src[0]);
 738                new_ce_len = cache_entry_size(len);
 739
 740                if (new_ce_len > ce_len) {
 741                        new_ce_len <<= 1;
 742                        tree_ce = xrealloc(tree_ce, new_ce_len);
 743                        memset(tree_ce, 0, new_ce_len);
 744                        ce_len = new_ce_len;
 745
 746                        tree_ce->ce_flags = create_ce_flags(0);
 747
 748                        for (d = 1; d <= nr_names; d++)
 749                                src[d] = tree_ce;
 750                }
 751
 752                tree_ce->ce_mode = src[0]->ce_mode;
 753                tree_ce->ce_namelen = len;
 754                oidcpy(&tree_ce->oid, &src[0]->oid);
 755                memcpy(tree_ce->name, src[0]->name, len + 1);
 756
 757                rc = call_unpack_fn((const struct cache_entry * const *)src, o);
 758                if (rc < 0) {
 759                        free(tree_ce);
 760                        return rc;
 761                }
 762
 763                mark_ce_used(src[0], o);
 764        }
 765        free(tree_ce);
 766        if (o->debug_unpack)
 767                printf("Unpacked %d entries from %s to %s using cache-tree\n",
 768                       nr_entries,
 769                       o->src_index->cache[pos]->name,
 770                       o->src_index->cache[pos + nr_entries - 1]->name);
 771        return 0;
 772}
 773
 774static int traverse_trees_recursive(int n, unsigned long dirmask,
 775                                    unsigned long df_conflicts,
 776                                    struct name_entry *names,
 777                                    struct traverse_info *info)
 778{
 779        struct unpack_trees_options *o = info->data;
 780        int i, ret, bottom;
 781        int nr_buf = 0;
 782        struct tree_desc t[MAX_UNPACK_TREES];
 783        void *buf[MAX_UNPACK_TREES];
 784        struct traverse_info newinfo;
 785        struct name_entry *p;
 786        int nr_entries;
 787
 788        nr_entries = all_trees_same_as_cache_tree(n, dirmask, names, info);
 789        if (nr_entries > 0) {
 790                int pos = index_pos_by_traverse_info(names, info);
 791
 792                if (!o->merge || df_conflicts)
 793                        BUG("Wrong condition to get here buddy");
 794
 795                /*
 796                 * All entries up to 'pos' must have been processed
 797                 * (i.e. marked CE_UNPACKED) at this point. But to be safe,
 798                 * save and restore cache_bottom anyway to not miss
 799                 * unprocessed entries before 'pos'.
 800                 */
 801                bottom = o->cache_bottom;
 802                ret = traverse_by_cache_tree(pos, nr_entries, n, info);
 803                o->cache_bottom = bottom;
 804                return ret;
 805        }
 806
 807        p = names;
 808        while (!p->mode)
 809                p++;
 810
 811        newinfo = *info;
 812        newinfo.prev = info;
 813        newinfo.pathspec = info->pathspec;
 814        newinfo.name = *p;
 815        newinfo.pathlen += tree_entry_len(p) + 1;
 816        newinfo.df_conflicts |= df_conflicts;
 817
 818        /*
 819         * Fetch the tree from the ODB for each peer directory in the
 820         * n commits.
 821         *
 822         * For 2- and 3-way traversals, we try to avoid hitting the
 823         * ODB twice for the same OID.  This should yield a nice speed
 824         * up in checkouts and merges when the commits are similar.
 825         *
 826         * We don't bother doing the full O(n^2) search for larger n,
 827         * because wider traversals don't happen that often and we
 828         * avoid the search setup.
 829         *
 830         * When 2 peer OIDs are the same, we just copy the tree
 831         * descriptor data.  This implicitly borrows the buffer
 832         * data from the earlier cell.
 833         */
 834        for (i = 0; i < n; i++, dirmask >>= 1) {
 835                if (i > 0 && are_same_oid(&names[i], &names[i - 1]))
 836                        t[i] = t[i - 1];
 837                else if (i > 1 && are_same_oid(&names[i], &names[i - 2]))
 838                        t[i] = t[i - 2];
 839                else {
 840                        const struct object_id *oid = NULL;
 841                        if (dirmask & 1)
 842                                oid = &names[i].oid;
 843                        buf[nr_buf++] = fill_tree_descriptor(t + i, oid);
 844                }
 845        }
 846
 847        bottom = switch_cache_bottom(&newinfo);
 848        ret = traverse_trees(o->src_index, n, t, &newinfo);
 849        restore_cache_bottom(&newinfo, bottom);
 850
 851        for (i = 0; i < nr_buf; i++)
 852                free(buf[i]);
 853
 854        return ret;
 855}
 856
 857/*
 858 * Compare the traverse-path to the cache entry without actually
 859 * having to generate the textual representation of the traverse
 860 * path.
 861 *
 862 * NOTE! This *only* compares up to the size of the traverse path
 863 * itself - the caller needs to do the final check for the cache
 864 * entry having more data at the end!
 865 */
 866static int do_compare_entry_piecewise(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 867{
 868        int len, pathlen, ce_len;
 869        const char *ce_name;
 870
 871        if (info->prev) {
 872                int cmp = do_compare_entry_piecewise(ce, info->prev,
 873                                                     &info->name);
 874                if (cmp)
 875                        return cmp;
 876        }
 877        pathlen = info->pathlen;
 878        ce_len = ce_namelen(ce);
 879
 880        /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 881        if (ce_len < pathlen)
 882                return -1;
 883
 884        ce_len -= pathlen;
 885        ce_name = ce->name + pathlen;
 886
 887        len = tree_entry_len(n);
 888        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 889}
 890
 891static int do_compare_entry(const struct cache_entry *ce,
 892                            const struct traverse_info *info,
 893                            const struct name_entry *n)
 894{
 895        int len, pathlen, ce_len;
 896        const char *ce_name;
 897        int cmp;
 898
 899        /*
 900         * If we have not precomputed the traverse path, it is quicker
 901         * to avoid doing so.  But if we have precomputed it,
 902         * it is quicker to use the precomputed version.
 903         */
 904        if (!info->traverse_path)
 905                return do_compare_entry_piecewise(ce, info, n);
 906
 907        cmp = strncmp(ce->name, info->traverse_path, info->pathlen);
 908        if (cmp)
 909                return cmp;
 910
 911        pathlen = info->pathlen;
 912        ce_len = ce_namelen(ce);
 913
 914        if (ce_len < pathlen)
 915                return -1;
 916
 917        ce_len -= pathlen;
 918        ce_name = ce->name + pathlen;
 919
 920        len = tree_entry_len(n);
 921        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 922}
 923
 924static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 925{
 926        int cmp = do_compare_entry(ce, info, n);
 927        if (cmp)
 928                return cmp;
 929
 930        /*
 931         * Even if the beginning compared identically, the ce should
 932         * compare as bigger than a directory leading up to it!
 933         */
 934        return ce_namelen(ce) > traverse_path_len(info, n);
 935}
 936
 937static int ce_in_traverse_path(const struct cache_entry *ce,
 938                               const struct traverse_info *info)
 939{
 940        if (!info->prev)
 941                return 1;
 942        if (do_compare_entry(ce, info->prev, &info->name))
 943                return 0;
 944        /*
 945         * If ce (blob) is the same name as the path (which is a tree
 946         * we will be descending into), it won't be inside it.
 947         */
 948        return (info->pathlen < ce_namelen(ce));
 949}
 950
 951static struct cache_entry *create_ce_entry(const struct traverse_info *info,
 952        const struct name_entry *n,
 953        int stage,
 954        struct index_state *istate,
 955        int is_transient)
 956{
 957        int len = traverse_path_len(info, n);
 958        struct cache_entry *ce =
 959                is_transient ?
 960                make_empty_transient_cache_entry(len) :
 961                make_empty_cache_entry(istate, len);
 962
 963        ce->ce_mode = create_ce_mode(n->mode);
 964        ce->ce_flags = create_ce_flags(stage);
 965        ce->ce_namelen = len;
 966        oidcpy(&ce->oid, &n->oid);
 967        make_traverse_path(ce->name, info, n);
 968
 969        return ce;
 970}
 971
 972/*
 973 * Note that traverse_by_cache_tree() duplicates some logic in this function
 974 * without actually calling it. If you change the logic here you may need to
 975 * check and change there as well.
 976 */
 977static int unpack_nondirectories(int n, unsigned long mask,
 978                                 unsigned long dirmask,
 979                                 struct cache_entry **src,
 980                                 const struct name_entry *names,
 981                                 const struct traverse_info *info)
 982{
 983        int i;
 984        struct unpack_trees_options *o = info->data;
 985        unsigned long conflicts = info->df_conflicts | dirmask;
 986
 987        /* Do we have *only* directories? Nothing to do */
 988        if (mask == dirmask && !src[0])
 989                return 0;
 990
 991        /*
 992         * Ok, we've filled in up to any potential index entry in src[0],
 993         * now do the rest.
 994         */
 995        for (i = 0; i < n; i++) {
 996                int stage;
 997                unsigned int bit = 1ul << i;
 998                if (conflicts & bit) {
 999                        src[i + o->merge] = o->df_conflict_entry;
1000                        continue;
1001                }
1002                if (!(mask & bit))
1003                        continue;
1004                if (!o->merge)
1005                        stage = 0;
1006                else if (i + 1 < o->head_idx)
1007                        stage = 1;
1008                else if (i + 1 > o->head_idx)
1009                        stage = 3;
1010                else
1011                        stage = 2;
1012
1013                /*
1014                 * If the merge bit is set, then the cache entries are
1015                 * discarded in the following block.  In this case,
1016                 * construct "transient" cache_entries, as they are
1017                 * not stored in the index.  otherwise construct the
1018                 * cache entry from the index aware logic.
1019                 */
1020                src[i + o->merge] = create_ce_entry(info, names + i, stage, &o->result, o->merge);
1021        }
1022
1023        if (o->merge) {
1024                int rc = call_unpack_fn((const struct cache_entry * const *)src,
1025                                        o);
1026                for (i = 0; i < n; i++) {
1027                        struct cache_entry *ce = src[i + o->merge];
1028                        if (ce != o->df_conflict_entry)
1029                                discard_cache_entry(ce);
1030                }
1031                return rc;
1032        }
1033
1034        for (i = 0; i < n; i++)
1035                if (src[i] && src[i] != o->df_conflict_entry)
1036                        if (do_add_entry(o, src[i], 0, 0))
1037                                return -1;
1038
1039        return 0;
1040}
1041
1042static int unpack_failed(struct unpack_trees_options *o, const char *message)
1043{
1044        discard_index(&o->result);
1045        if (!o->quiet && !o->exiting_early) {
1046                if (message)
1047                        return error("%s", message);
1048                return -1;
1049        }
1050        return -1;
1051}
1052
1053/*
1054 * The tree traversal is looking at name p.  If we have a matching entry,
1055 * return it.  If name p is a directory in the index, do not return
1056 * anything, as we will want to match it when the traversal descends into
1057 * the directory.
1058 */
1059static int find_cache_pos(struct traverse_info *info,
1060                          const struct name_entry *p)
1061{
1062        int pos;
1063        struct unpack_trees_options *o = info->data;
1064        struct index_state *index = o->src_index;
1065        int pfxlen = info->pathlen;
1066        int p_len = tree_entry_len(p);
1067
1068        for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
1069                const struct cache_entry *ce = index->cache[pos];
1070                const char *ce_name, *ce_slash;
1071                int cmp, ce_len;
1072
1073                if (ce->ce_flags & CE_UNPACKED) {
1074                        /*
1075                         * cache_bottom entry is already unpacked, so
1076                         * we can never match it; don't check it
1077                         * again.
1078                         */
1079                        if (pos == o->cache_bottom)
1080                                ++o->cache_bottom;
1081                        continue;
1082                }
1083                if (!ce_in_traverse_path(ce, info)) {
1084                        /*
1085                         * Check if we can skip future cache checks
1086                         * (because we're already past all possible
1087                         * entries in the traverse path).
1088                         */
1089                        if (info->traverse_path) {
1090                                if (strncmp(ce->name, info->traverse_path,
1091                                            info->pathlen) > 0)
1092                                        break;
1093                        }
1094                        continue;
1095                }
1096                ce_name = ce->name + pfxlen;
1097                ce_slash = strchr(ce_name, '/');
1098                if (ce_slash)
1099                        ce_len = ce_slash - ce_name;
1100                else
1101                        ce_len = ce_namelen(ce) - pfxlen;
1102                cmp = name_compare(p->path, p_len, ce_name, ce_len);
1103                /*
1104                 * Exact match; if we have a directory we need to
1105                 * delay returning it.
1106                 */
1107                if (!cmp)
1108                        return ce_slash ? -2 - pos : pos;
1109                if (0 < cmp)
1110                        continue; /* keep looking */
1111                /*
1112                 * ce_name sorts after p->path; could it be that we
1113                 * have files under p->path directory in the index?
1114                 * E.g.  ce_name == "t-i", and p->path == "t"; we may
1115                 * have "t/a" in the index.
1116                 */
1117                if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
1118                    ce_name[p_len] < '/')
1119                        continue; /* keep looking */
1120                break;
1121        }
1122        return -1;
1123}
1124
1125static struct cache_entry *find_cache_entry(struct traverse_info *info,
1126                                            const struct name_entry *p)
1127{
1128        int pos = find_cache_pos(info, p);
1129        struct unpack_trees_options *o = info->data;
1130
1131        if (0 <= pos)
1132                return o->src_index->cache[pos];
1133        else
1134                return NULL;
1135}
1136
1137static void debug_path(struct traverse_info *info)
1138{
1139        if (info->prev) {
1140                debug_path(info->prev);
1141                if (*info->prev->name.path)
1142                        putchar('/');
1143        }
1144        printf("%s", info->name.path);
1145}
1146
1147static void debug_name_entry(int i, struct name_entry *n)
1148{
1149        printf("ent#%d %06o %s\n", i,
1150               n->path ? n->mode : 0,
1151               n->path ? n->path : "(missing)");
1152}
1153
1154static void debug_unpack_callback(int n,
1155                                  unsigned long mask,
1156                                  unsigned long dirmask,
1157                                  struct name_entry *names,
1158                                  struct traverse_info *info)
1159{
1160        int i;
1161        printf("* unpack mask %lu, dirmask %lu, cnt %d ",
1162               mask, dirmask, n);
1163        debug_path(info);
1164        putchar('\n');
1165        for (i = 0; i < n; i++)
1166                debug_name_entry(i, names + i);
1167}
1168
1169/*
1170 * Note that traverse_by_cache_tree() duplicates some logic in this function
1171 * without actually calling it. If you change the logic here you may need to
1172 * check and change there as well.
1173 */
1174static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
1175{
1176        struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
1177        struct unpack_trees_options *o = info->data;
1178        const struct name_entry *p = names;
1179
1180        /* Find first entry with a real name (we could use "mask" too) */
1181        while (!p->mode)
1182                p++;
1183
1184        if (o->debug_unpack)
1185                debug_unpack_callback(n, mask, dirmask, names, info);
1186
1187        /* Are we supposed to look at the index too? */
1188        if (o->merge) {
1189                while (1) {
1190                        int cmp;
1191                        struct cache_entry *ce;
1192
1193                        if (o->diff_index_cached)
1194                                ce = next_cache_entry(o);
1195                        else
1196                                ce = find_cache_entry(info, p);
1197
1198                        if (!ce)
1199                                break;
1200                        cmp = compare_entry(ce, info, p);
1201                        if (cmp < 0) {
1202                                if (unpack_index_entry(ce, o) < 0)
1203                                        return unpack_failed(o, NULL);
1204                                continue;
1205                        }
1206                        if (!cmp) {
1207                                if (ce_stage(ce)) {
1208                                        /*
1209                                         * If we skip unmerged index
1210                                         * entries, we'll skip this
1211                                         * entry *and* the tree
1212                                         * entries associated with it!
1213                                         */
1214                                        if (o->skip_unmerged) {
1215                                                add_same_unmerged(ce, o);
1216                                                return mask;
1217                                        }
1218                                }
1219                                src[0] = ce;
1220                        }
1221                        break;
1222                }
1223        }
1224
1225        if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
1226                return -1;
1227
1228        if (o->merge && src[0]) {
1229                if (ce_stage(src[0]))
1230                        mark_ce_used_same_name(src[0], o);
1231                else
1232                        mark_ce_used(src[0], o);
1233        }
1234
1235        /* Now handle any directories.. */
1236        if (dirmask) {
1237                /* special case: "diff-index --cached" looking at a tree */
1238                if (o->diff_index_cached &&
1239                    n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
1240                        int matches;
1241                        matches = cache_tree_matches_traversal(o->src_index->cache_tree,
1242                                                               names, info);
1243                        /*
1244                         * Everything under the name matches; skip the
1245                         * entire hierarchy.  diff_index_cached codepath
1246                         * special cases D/F conflicts in such a way that
1247                         * it does not do any look-ahead, so this is safe.
1248                         */
1249                        if (matches) {
1250                                o->cache_bottom += matches;
1251                                return mask;
1252                        }
1253                }
1254
1255                if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
1256                                             names, info) < 0)
1257                        return -1;
1258                return mask;
1259        }
1260
1261        return mask;
1262}
1263
1264static int clear_ce_flags_1(struct index_state *istate,
1265                            struct cache_entry **cache, int nr,
1266                            struct strbuf *prefix,
1267                            int select_mask, int clear_mask,
1268                            struct exclude_list *el, int defval);
1269
1270/* Whole directory matching */
1271static int clear_ce_flags_dir(struct index_state *istate,
1272                              struct cache_entry **cache, int nr,
1273                              struct strbuf *prefix,
1274                              char *basename,
1275                              int select_mask, int clear_mask,
1276                              struct exclude_list *el, int defval)
1277{
1278        struct cache_entry **cache_end;
1279        int dtype = DT_DIR;
1280        int ret = is_excluded_from_list(prefix->buf, prefix->len,
1281                                        basename, &dtype, el, istate);
1282        int rc;
1283
1284        strbuf_addch(prefix, '/');
1285
1286        /* If undecided, use matching result of parent dir in defval */
1287        if (ret < 0)
1288                ret = defval;
1289
1290        for (cache_end = cache; cache_end != cache + nr; cache_end++) {
1291                struct cache_entry *ce = *cache_end;
1292                if (strncmp(ce->name, prefix->buf, prefix->len))
1293                        break;
1294        }
1295
1296        /*
1297         * TODO: check el, if there are no patterns that may conflict
1298         * with ret (iow, we know in advance the incl/excl
1299         * decision for the entire directory), clear flag here without
1300         * calling clear_ce_flags_1(). That function will call
1301         * the expensive is_excluded_from_list() on every entry.
1302         */
1303        rc = clear_ce_flags_1(istate, cache, cache_end - cache,
1304                              prefix,
1305                              select_mask, clear_mask,
1306                              el, ret);
1307        strbuf_setlen(prefix, prefix->len - 1);
1308        return rc;
1309}
1310
1311/*
1312 * Traverse the index, find every entry that matches according to
1313 * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
1314 * number of traversed entries.
1315 *
1316 * If select_mask is non-zero, only entries whose ce_flags has on of
1317 * those bits enabled are traversed.
1318 *
1319 * cache        : pointer to an index entry
1320 * prefix_len   : an offset to its path
1321 *
1322 * The current path ("prefix") including the trailing '/' is
1323 *   cache[0]->name[0..(prefix_len-1)]
1324 * Top level path has prefix_len zero.
1325 */
1326static int clear_ce_flags_1(struct index_state *istate,
1327                            struct cache_entry **cache, int nr,
1328                            struct strbuf *prefix,
1329                            int select_mask, int clear_mask,
1330                            struct exclude_list *el, int defval)
1331{
1332        struct cache_entry **cache_end = cache + nr;
1333
1334        /*
1335         * Process all entries that have the given prefix and meet
1336         * select_mask condition
1337         */
1338        while(cache != cache_end) {
1339                struct cache_entry *ce = *cache;
1340                const char *name, *slash;
1341                int len, dtype, ret;
1342
1343                if (select_mask && !(ce->ce_flags & select_mask)) {
1344                        cache++;
1345                        continue;
1346                }
1347
1348                if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
1349                        break;
1350
1351                name = ce->name + prefix->len;
1352                slash = strchr(name, '/');
1353
1354                /* If it's a directory, try whole directory match first */
1355                if (slash) {
1356                        int processed;
1357
1358                        len = slash - name;
1359                        strbuf_add(prefix, name, len);
1360
1361                        processed = clear_ce_flags_dir(istate, cache, cache_end - cache,
1362                                                       prefix,
1363                                                       prefix->buf + prefix->len - len,
1364                                                       select_mask, clear_mask,
1365                                                       el, defval);
1366
1367                        /* clear_c_f_dir eats a whole dir already? */
1368                        if (processed) {
1369                                cache += processed;
1370                                strbuf_setlen(prefix, prefix->len - len);
1371                                continue;
1372                        }
1373
1374                        strbuf_addch(prefix, '/');
1375                        cache += clear_ce_flags_1(istate, cache, cache_end - cache,
1376                                                  prefix,
1377                                                  select_mask, clear_mask, el, defval);
1378                        strbuf_setlen(prefix, prefix->len - len - 1);
1379                        continue;
1380                }
1381
1382                /* Non-directory */
1383                dtype = ce_to_dtype(ce);
1384                ret = is_excluded_from_list(ce->name, ce_namelen(ce),
1385                                            name, &dtype, el, istate);
1386                if (ret < 0)
1387                        ret = defval;
1388                if (ret > 0)
1389                        ce->ce_flags &= ~clear_mask;
1390                cache++;
1391        }
1392        return nr - (cache_end - cache);
1393}
1394
1395static int clear_ce_flags(struct index_state *istate,
1396                          int select_mask, int clear_mask,
1397                          struct exclude_list *el)
1398{
1399        static struct strbuf prefix = STRBUF_INIT;
1400
1401        strbuf_reset(&prefix);
1402
1403        return clear_ce_flags_1(istate,
1404                                istate->cache,
1405                                istate->cache_nr,
1406                                &prefix,
1407                                select_mask, clear_mask,
1408                                el, 0);
1409}
1410
1411/*
1412 * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
1413 */
1414static void mark_new_skip_worktree(struct exclude_list *el,
1415                                   struct index_state *istate,
1416                                   int select_flag, int skip_wt_flag)
1417{
1418        int i;
1419
1420        /*
1421         * 1. Pretend the narrowest worktree: only unmerged entries
1422         * are checked out
1423         */
1424        for (i = 0; i < istate->cache_nr; i++) {
1425                struct cache_entry *ce = istate->cache[i];
1426
1427                if (select_flag && !(ce->ce_flags & select_flag))
1428                        continue;
1429
1430                if (!ce_stage(ce) && !(ce->ce_flags & CE_CONFLICTED))
1431                        ce->ce_flags |= skip_wt_flag;
1432                else
1433                        ce->ce_flags &= ~skip_wt_flag;
1434        }
1435
1436        /*
1437         * 2. Widen worktree according to sparse-checkout file.
1438         * Matched entries will have skip_wt_flag cleared (i.e. "in")
1439         */
1440        clear_ce_flags(istate, select_flag, skip_wt_flag, el);
1441}
1442
1443static int verify_absent(const struct cache_entry *,
1444                         enum unpack_trees_error_types,
1445                         struct unpack_trees_options *);
1446/*
1447 * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1448 * resulting index, -2 on failure to reflect the changes to the work tree.
1449 *
1450 * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1451 */
1452int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1453{
1454        int i, ret;
1455        static struct cache_entry *dfc;
1456        struct exclude_list el;
1457
1458        if (len > MAX_UNPACK_TREES)
1459                die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1460
1461        trace_performance_enter();
1462        memset(&el, 0, sizeof(el));
1463        if (!core_apply_sparse_checkout || !o->update)
1464                o->skip_sparse_checkout = 1;
1465        if (!o->skip_sparse_checkout) {
1466                char *sparse = git_pathdup("info/sparse-checkout");
1467                if (add_excludes_from_file_to_list(sparse, "", 0, &el, NULL) < 0)
1468                        o->skip_sparse_checkout = 1;
1469                else
1470                        o->el = &el;
1471                free(sparse);
1472        }
1473
1474        memset(&o->result, 0, sizeof(o->result));
1475        o->result.initialized = 1;
1476        o->result.timestamp.sec = o->src_index->timestamp.sec;
1477        o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1478        o->result.version = o->src_index->version;
1479        if (!o->src_index->split_index) {
1480                o->result.split_index = NULL;
1481        } else if (o->src_index == o->dst_index) {
1482                /*
1483                 * o->dst_index (and thus o->src_index) will be discarded
1484                 * and overwritten with o->result at the end of this function,
1485                 * so just use src_index's split_index to avoid having to
1486                 * create a new one.
1487                 */
1488                o->result.split_index = o->src_index->split_index;
1489                o->result.split_index->refcount++;
1490        } else {
1491                o->result.split_index = init_split_index(&o->result);
1492        }
1493        oidcpy(&o->result.oid, &o->src_index->oid);
1494        o->merge_size = len;
1495        mark_all_ce_unused(o->src_index);
1496
1497        /*
1498         * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1499         */
1500        if (!o->skip_sparse_checkout)
1501                mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1502
1503        if (!dfc)
1504                dfc = xcalloc(1, cache_entry_size(0));
1505        o->df_conflict_entry = dfc;
1506
1507        if (len) {
1508                const char *prefix = o->prefix ? o->prefix : "";
1509                struct traverse_info info;
1510
1511                setup_traverse_info(&info, prefix);
1512                info.fn = unpack_callback;
1513                info.data = o;
1514                info.show_all_errors = o->show_all_errors;
1515                info.pathspec = o->pathspec;
1516
1517                if (o->prefix) {
1518                        /*
1519                         * Unpack existing index entries that sort before the
1520                         * prefix the tree is spliced into.  Note that o->merge
1521                         * is always true in this case.
1522                         */
1523                        while (1) {
1524                                struct cache_entry *ce = next_cache_entry(o);
1525                                if (!ce)
1526                                        break;
1527                                if (ce_in_traverse_path(ce, &info))
1528                                        break;
1529                                if (unpack_index_entry(ce, o) < 0)
1530                                        goto return_failed;
1531                        }
1532                }
1533
1534                trace_performance_enter();
1535                ret = traverse_trees(o->src_index, len, t, &info);
1536                trace_performance_leave("traverse_trees");
1537                if (ret < 0)
1538                        goto return_failed;
1539        }
1540
1541        /* Any left-over entries in the index? */
1542        if (o->merge) {
1543                while (1) {
1544                        struct cache_entry *ce = next_cache_entry(o);
1545                        if (!ce)
1546                                break;
1547                        if (unpack_index_entry(ce, o) < 0)
1548                                goto return_failed;
1549                }
1550        }
1551        mark_all_ce_unused(o->src_index);
1552
1553        if (o->trivial_merges_only && o->nontrivial_merge) {
1554                ret = unpack_failed(o, "Merge requires file-level merging");
1555                goto done;
1556        }
1557
1558        if (!o->skip_sparse_checkout) {
1559                int empty_worktree = 1;
1560
1561                /*
1562                 * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1563                 * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1564                 * so apply_sparse_checkout() won't attempt to remove it from worktree
1565                 */
1566                mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1567
1568                ret = 0;
1569                for (i = 0; i < o->result.cache_nr; i++) {
1570                        struct cache_entry *ce = o->result.cache[i];
1571
1572                        /*
1573                         * Entries marked with CE_ADDED in merged_entry() do not have
1574                         * verify_absent() check (the check is effectively disabled
1575                         * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1576                         *
1577                         * Do the real check now because we have had
1578                         * correct CE_NEW_SKIP_WORKTREE
1579                         */
1580                        if (ce->ce_flags & CE_ADDED &&
1581                            verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1582                                if (!o->show_all_errors)
1583                                        goto return_failed;
1584                                ret = -1;
1585                        }
1586
1587                        if (apply_sparse_checkout(&o->result, ce, o)) {
1588                                if (!o->show_all_errors)
1589                                        goto return_failed;
1590                                ret = -1;
1591                        }
1592                        if (!ce_skip_worktree(ce))
1593                                empty_worktree = 0;
1594
1595                }
1596                if (ret < 0)
1597                        goto return_failed;
1598                /*
1599                 * Sparse checkout is meant to narrow down checkout area
1600                 * but it does not make sense to narrow down to empty working
1601                 * tree. This is usually a mistake in sparse checkout rules.
1602                 * Do not allow users to do that.
1603                 */
1604                if (o->result.cache_nr && empty_worktree) {
1605                        ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1606                        goto done;
1607                }
1608        }
1609
1610        ret = check_updates(o) ? (-2) : 0;
1611        if (o->dst_index) {
1612                move_index_extensions(&o->result, o->src_index);
1613                if (!ret) {
1614                        if (git_env_bool("GIT_TEST_CHECK_CACHE_TREE", 0))
1615                                cache_tree_verify(the_repository, &o->result);
1616                        if (!o->result.cache_tree)
1617                                o->result.cache_tree = cache_tree();
1618                        if (!cache_tree_fully_valid(o->result.cache_tree))
1619                                cache_tree_update(&o->result,
1620                                                  WRITE_TREE_SILENT |
1621                                                  WRITE_TREE_REPAIR);
1622                }
1623
1624                o->result.updated_workdir = 1;
1625                discard_index(o->dst_index);
1626                *o->dst_index = o->result;
1627        } else {
1628                discard_index(&o->result);
1629        }
1630        o->src_index = NULL;
1631
1632done:
1633        trace_performance_leave("unpack_trees");
1634        clear_exclude_list(&el);
1635        return ret;
1636
1637return_failed:
1638        if (o->show_all_errors)
1639                display_error_msgs(o);
1640        mark_all_ce_unused(o->src_index);
1641        ret = unpack_failed(o, NULL);
1642        if (o->exiting_early)
1643                ret = 0;
1644        goto done;
1645}
1646
1647/* Here come the merge functions */
1648
1649static int reject_merge(const struct cache_entry *ce,
1650                        struct unpack_trees_options *o)
1651{
1652        return add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1653}
1654
1655static int same(const struct cache_entry *a, const struct cache_entry *b)
1656{
1657        if (!!a != !!b)
1658                return 0;
1659        if (!a && !b)
1660                return 1;
1661        if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1662                return 0;
1663        return a->ce_mode == b->ce_mode &&
1664               oideq(&a->oid, &b->oid);
1665}
1666
1667
1668/*
1669 * When a CE gets turned into an unmerged entry, we
1670 * want it to be up-to-date
1671 */
1672static int verify_uptodate_1(const struct cache_entry *ce,
1673                             struct unpack_trees_options *o,
1674                             enum unpack_trees_error_types error_type)
1675{
1676        struct stat st;
1677
1678        if (o->index_only)
1679                return 0;
1680
1681        /*
1682         * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1683         * if this entry is truly up-to-date because this file may be
1684         * overwritten.
1685         */
1686        if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1687                ; /* keep checking */
1688        else if (o->reset || ce_uptodate(ce))
1689                return 0;
1690
1691        if (!lstat(ce->name, &st)) {
1692                int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1693                unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1694
1695                if (submodule_from_ce(ce)) {
1696                        int r = check_submodule_move_head(ce,
1697                                "HEAD", oid_to_hex(&ce->oid), o);
1698                        if (r)
1699                                return add_rejected_path(o, error_type, ce->name);
1700                        return 0;
1701                }
1702
1703                if (!changed)
1704                        return 0;
1705                /*
1706                 * Historic default policy was to allow submodule to be out
1707                 * of sync wrt the superproject index. If the submodule was
1708                 * not considered interesting above, we don't care here.
1709                 */
1710                if (S_ISGITLINK(ce->ce_mode))
1711                        return 0;
1712
1713                errno = 0;
1714        }
1715        if (errno == ENOENT)
1716                return 0;
1717        return add_rejected_path(o, error_type, ce->name);
1718}
1719
1720int verify_uptodate(const struct cache_entry *ce,
1721                    struct unpack_trees_options *o)
1722{
1723        if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1724                return 0;
1725        return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1726}
1727
1728static int verify_uptodate_sparse(const struct cache_entry *ce,
1729                                  struct unpack_trees_options *o)
1730{
1731        return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1732}
1733
1734/*
1735 * TODO: We should actually invalidate o->result, not src_index [1].
1736 * But since cache tree and untracked cache both are not copied to
1737 * o->result until unpacking is complete, we invalidate them on
1738 * src_index instead with the assumption that they will be copied to
1739 * dst_index at the end.
1740 *
1741 * [1] src_index->cache_tree is also used in unpack_callback() so if
1742 * we invalidate o->result, we need to update it to use
1743 * o->result.cache_tree as well.
1744 */
1745static void invalidate_ce_path(const struct cache_entry *ce,
1746                               struct unpack_trees_options *o)
1747{
1748        if (!ce)
1749                return;
1750        cache_tree_invalidate_path(o->src_index, ce->name);
1751        untracked_cache_invalidate_path(o->src_index, ce->name, 1);
1752}
1753
1754/*
1755 * Check that checking out ce->sha1 in subdir ce->name is not
1756 * going to overwrite any working files.
1757 *
1758 * Currently, git does not checkout subprojects during a superproject
1759 * checkout, so it is not going to overwrite anything.
1760 */
1761static int verify_clean_submodule(const char *old_sha1,
1762                                  const struct cache_entry *ce,
1763                                  struct unpack_trees_options *o)
1764{
1765        if (!submodule_from_ce(ce))
1766                return 0;
1767
1768        return check_submodule_move_head(ce, old_sha1,
1769                                         oid_to_hex(&ce->oid), o);
1770}
1771
1772static int verify_clean_subdirectory(const struct cache_entry *ce,
1773                                     struct unpack_trees_options *o)
1774{
1775        /*
1776         * we are about to extract "ce->name"; we would not want to lose
1777         * anything in the existing directory there.
1778         */
1779        int namelen;
1780        int i;
1781        struct dir_struct d;
1782        char *pathbuf;
1783        int cnt = 0;
1784
1785        if (S_ISGITLINK(ce->ce_mode)) {
1786                struct object_id oid;
1787                int sub_head = resolve_gitlink_ref(ce->name, "HEAD", &oid);
1788                /*
1789                 * If we are not going to update the submodule, then
1790                 * we don't care.
1791                 */
1792                if (!sub_head && oideq(&oid, &ce->oid))
1793                        return 0;
1794                return verify_clean_submodule(sub_head ? NULL : oid_to_hex(&oid),
1795                                              ce, o);
1796        }
1797
1798        /*
1799         * First let's make sure we do not have a local modification
1800         * in that directory.
1801         */
1802        namelen = ce_namelen(ce);
1803        for (i = locate_in_src_index(ce, o);
1804             i < o->src_index->cache_nr;
1805             i++) {
1806                struct cache_entry *ce2 = o->src_index->cache[i];
1807                int len = ce_namelen(ce2);
1808                if (len < namelen ||
1809                    strncmp(ce->name, ce2->name, namelen) ||
1810                    ce2->name[namelen] != '/')
1811                        break;
1812                /*
1813                 * ce2->name is an entry in the subdirectory to be
1814                 * removed.
1815                 */
1816                if (!ce_stage(ce2)) {
1817                        if (verify_uptodate(ce2, o))
1818                                return -1;
1819                        add_entry(o, ce2, CE_REMOVE, 0);
1820                        invalidate_ce_path(ce, o);
1821                        mark_ce_used(ce2, o);
1822                }
1823                cnt++;
1824        }
1825
1826        /*
1827         * Then we need to make sure that we do not lose a locally
1828         * present file that is not ignored.
1829         */
1830        pathbuf = xstrfmt("%.*s/", namelen, ce->name);
1831
1832        memset(&d, 0, sizeof(d));
1833        if (o->dir)
1834                d.exclude_per_dir = o->dir->exclude_per_dir;
1835        i = read_directory(&d, o->src_index, pathbuf, namelen+1, NULL);
1836        if (i)
1837                return add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1838        free(pathbuf);
1839        return cnt;
1840}
1841
1842/*
1843 * This gets called when there was no index entry for the tree entry 'dst',
1844 * but we found a file in the working tree that 'lstat()' said was fine,
1845 * and we're on a case-insensitive filesystem.
1846 *
1847 * See if we can find a case-insensitive match in the index that also
1848 * matches the stat information, and assume it's that other file!
1849 */
1850static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1851{
1852        const struct cache_entry *src;
1853
1854        src = index_file_exists(o->src_index, name, len, 1);
1855        return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1856}
1857
1858static int check_ok_to_remove(const char *name, int len, int dtype,
1859                              const struct cache_entry *ce, struct stat *st,
1860                              enum unpack_trees_error_types error_type,
1861                              struct unpack_trees_options *o)
1862{
1863        const struct cache_entry *result;
1864
1865        /*
1866         * It may be that the 'lstat()' succeeded even though
1867         * target 'ce' was absent, because there is an old
1868         * entry that is different only in case..
1869         *
1870         * Ignore that lstat() if it matches.
1871         */
1872        if (ignore_case && icase_exists(o, name, len, st))
1873                return 0;
1874
1875        if (o->dir &&
1876            is_excluded(o->dir, o->src_index, name, &dtype))
1877                /*
1878                 * ce->name is explicitly excluded, so it is Ok to
1879                 * overwrite it.
1880                 */
1881                return 0;
1882        if (S_ISDIR(st->st_mode)) {
1883                /*
1884                 * We are checking out path "foo" and
1885                 * found "foo/." in the working tree.
1886                 * This is tricky -- if we have modified
1887                 * files that are in "foo/" we would lose
1888                 * them.
1889                 */
1890                if (verify_clean_subdirectory(ce, o) < 0)
1891                        return -1;
1892                return 0;
1893        }
1894
1895        /*
1896         * The previous round may already have decided to
1897         * delete this path, which is in a subdirectory that
1898         * is being replaced with a blob.
1899         */
1900        result = index_file_exists(&o->result, name, len, 0);
1901        if (result) {
1902                if (result->ce_flags & CE_REMOVE)
1903                        return 0;
1904        }
1905
1906        return add_rejected_path(o, error_type, name);
1907}
1908
1909/*
1910 * We do not want to remove or overwrite a working tree file that
1911 * is not tracked, unless it is ignored.
1912 */
1913static int verify_absent_1(const struct cache_entry *ce,
1914                           enum unpack_trees_error_types error_type,
1915                           struct unpack_trees_options *o)
1916{
1917        int len;
1918        struct stat st;
1919
1920        if (o->index_only || o->reset || !o->update)
1921                return 0;
1922
1923        len = check_leading_path(ce->name, ce_namelen(ce));
1924        if (!len)
1925                return 0;
1926        else if (len > 0) {
1927                char *path;
1928                int ret;
1929
1930                path = xmemdupz(ce->name, len);
1931                if (lstat(path, &st))
1932                        ret = error_errno("cannot stat '%s'", path);
1933                else {
1934                        if (submodule_from_ce(ce))
1935                                ret = check_submodule_move_head(ce,
1936                                                                oid_to_hex(&ce->oid),
1937                                                                NULL, o);
1938                        else
1939                                ret = check_ok_to_remove(path, len, DT_UNKNOWN, NULL,
1940                                                         &st, error_type, o);
1941                }
1942                free(path);
1943                return ret;
1944        } else if (lstat(ce->name, &st)) {
1945                if (errno != ENOENT)
1946                        return error_errno("cannot stat '%s'", ce->name);
1947                return 0;
1948        } else {
1949                if (submodule_from_ce(ce))
1950                        return check_submodule_move_head(ce, oid_to_hex(&ce->oid),
1951                                                         NULL, o);
1952
1953                return check_ok_to_remove(ce->name, ce_namelen(ce),
1954                                          ce_to_dtype(ce), ce, &st,
1955                                          error_type, o);
1956        }
1957}
1958
1959static int verify_absent(const struct cache_entry *ce,
1960                         enum unpack_trees_error_types error_type,
1961                         struct unpack_trees_options *o)
1962{
1963        if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1964                return 0;
1965        return verify_absent_1(ce, error_type, o);
1966}
1967
1968static int verify_absent_sparse(const struct cache_entry *ce,
1969                                enum unpack_trees_error_types error_type,
1970                                struct unpack_trees_options *o)
1971{
1972        enum unpack_trees_error_types orphaned_error = error_type;
1973        if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1974                orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1975
1976        return verify_absent_1(ce, orphaned_error, o);
1977}
1978
1979static int merged_entry(const struct cache_entry *ce,
1980                        const struct cache_entry *old,
1981                        struct unpack_trees_options *o)
1982{
1983        int update = CE_UPDATE;
1984        struct cache_entry *merge = dup_cache_entry(ce, &o->result);
1985
1986        if (!old) {
1987                /*
1988                 * New index entries. In sparse checkout, the following
1989                 * verify_absent() will be delayed until after
1990                 * traverse_trees() finishes in unpack_trees(), then:
1991                 *
1992                 *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1993                 *  - verify_absent() be called again, this time with
1994                 *    correct CE_NEW_SKIP_WORKTREE
1995                 *
1996                 * verify_absent() call here does nothing in sparse
1997                 * checkout (i.e. o->skip_sparse_checkout == 0)
1998                 */
1999                update |= CE_ADDED;
2000                merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
2001
2002                if (verify_absent(merge,
2003                                  ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
2004                        discard_cache_entry(merge);
2005                        return -1;
2006                }
2007                invalidate_ce_path(merge, o);
2008
2009                if (submodule_from_ce(ce)) {
2010                        int ret = check_submodule_move_head(ce, NULL,
2011                                                            oid_to_hex(&ce->oid),
2012                                                            o);
2013                        if (ret)
2014                                return ret;
2015                }
2016
2017        } else if (!(old->ce_flags & CE_CONFLICTED)) {
2018                /*
2019                 * See if we can re-use the old CE directly?
2020                 * That way we get the uptodate stat info.
2021                 *
2022                 * This also removes the UPDATE flag on a match; otherwise
2023                 * we will end up overwriting local changes in the work tree.
2024                 */
2025                if (same(old, merge)) {
2026                        copy_cache_entry(merge, old);
2027                        update = 0;
2028                } else {
2029                        if (verify_uptodate(old, o)) {
2030                                discard_cache_entry(merge);
2031                                return -1;
2032                        }
2033                        /* Migrate old flags over */
2034                        update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
2035                        invalidate_ce_path(old, o);
2036                }
2037
2038                if (submodule_from_ce(ce)) {
2039                        int ret = check_submodule_move_head(ce, oid_to_hex(&old->oid),
2040                                                            oid_to_hex(&ce->oid),
2041                                                            o);
2042                        if (ret)
2043                                return ret;
2044                }
2045        } else {
2046                /*
2047                 * Previously unmerged entry left as an existence
2048                 * marker by read_index_unmerged();
2049                 */
2050                invalidate_ce_path(old, o);
2051        }
2052
2053        do_add_entry(o, merge, update, CE_STAGEMASK);
2054        return 1;
2055}
2056
2057static int deleted_entry(const struct cache_entry *ce,
2058                         const struct cache_entry *old,
2059                         struct unpack_trees_options *o)
2060{
2061        /* Did it exist in the index? */
2062        if (!old) {
2063                if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
2064                        return -1;
2065                return 0;
2066        }
2067        if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
2068                return -1;
2069        add_entry(o, ce, CE_REMOVE, 0);
2070        invalidate_ce_path(ce, o);
2071        return 1;
2072}
2073
2074static int keep_entry(const struct cache_entry *ce,
2075                      struct unpack_trees_options *o)
2076{
2077        add_entry(o, ce, 0, 0);
2078        if (ce_stage(ce))
2079                invalidate_ce_path(ce, o);
2080        return 1;
2081}
2082
2083#if DBRT_DEBUG
2084static void show_stage_entry(FILE *o,
2085                             const char *label, const struct cache_entry *ce)
2086{
2087        if (!ce)
2088                fprintf(o, "%s (missing)\n", label);
2089        else
2090                fprintf(o, "%s%06o %s %d\t%s\n",
2091                        label,
2092                        ce->ce_mode,
2093                        oid_to_hex(&ce->oid),
2094                        ce_stage(ce),
2095                        ce->name);
2096}
2097#endif
2098
2099int threeway_merge(const struct cache_entry * const *stages,
2100                   struct unpack_trees_options *o)
2101{
2102        const struct cache_entry *index;
2103        const struct cache_entry *head;
2104        const struct cache_entry *remote = stages[o->head_idx + 1];
2105        int count;
2106        int head_match = 0;
2107        int remote_match = 0;
2108
2109        int df_conflict_head = 0;
2110        int df_conflict_remote = 0;
2111
2112        int any_anc_missing = 0;
2113        int no_anc_exists = 1;
2114        int i;
2115
2116        for (i = 1; i < o->head_idx; i++) {
2117                if (!stages[i] || stages[i] == o->df_conflict_entry)
2118                        any_anc_missing = 1;
2119                else
2120                        no_anc_exists = 0;
2121        }
2122
2123        index = stages[0];
2124        head = stages[o->head_idx];
2125
2126        if (head == o->df_conflict_entry) {
2127                df_conflict_head = 1;
2128                head = NULL;
2129        }
2130
2131        if (remote == o->df_conflict_entry) {
2132                df_conflict_remote = 1;
2133                remote = NULL;
2134        }
2135
2136        /*
2137         * First, if there's a #16 situation, note that to prevent #13
2138         * and #14.
2139         */
2140        if (!same(remote, head)) {
2141                for (i = 1; i < o->head_idx; i++) {
2142                        if (same(stages[i], head)) {
2143                                head_match = i;
2144                        }
2145                        if (same(stages[i], remote)) {
2146                                remote_match = i;
2147                        }
2148                }
2149        }
2150
2151        /*
2152         * We start with cases where the index is allowed to match
2153         * something other than the head: #14(ALT) and #2ALT, where it
2154         * is permitted to match the result instead.
2155         */
2156        /* #14, #14ALT, #2ALT */
2157        if (remote && !df_conflict_head && head_match && !remote_match) {
2158                if (index && !same(index, remote) && !same(index, head))
2159                        return reject_merge(index, o);
2160                return merged_entry(remote, index, o);
2161        }
2162        /*
2163         * If we have an entry in the index cache, then we want to
2164         * make sure that it matches head.
2165         */
2166        if (index && !same(index, head))
2167                return reject_merge(index, o);
2168
2169        if (head) {
2170                /* #5ALT, #15 */
2171                if (same(head, remote))
2172                        return merged_entry(head, index, o);
2173                /* #13, #3ALT */
2174                if (!df_conflict_remote && remote_match && !head_match)
2175                        return merged_entry(head, index, o);
2176        }
2177
2178        /* #1 */
2179        if (!head && !remote && any_anc_missing)
2180                return 0;
2181
2182        /*
2183         * Under the "aggressive" rule, we resolve mostly trivial
2184         * cases that we historically had git-merge-one-file resolve.
2185         */
2186        if (o->aggressive) {
2187                int head_deleted = !head;
2188                int remote_deleted = !remote;
2189                const struct cache_entry *ce = NULL;
2190
2191                if (index)
2192                        ce = index;
2193                else if (head)
2194                        ce = head;
2195                else if (remote)
2196                        ce = remote;
2197                else {
2198                        for (i = 1; i < o->head_idx; i++) {
2199                                if (stages[i] && stages[i] != o->df_conflict_entry) {
2200                                        ce = stages[i];
2201                                        break;
2202                                }
2203                        }
2204                }
2205
2206                /*
2207                 * Deleted in both.
2208                 * Deleted in one and unchanged in the other.
2209                 */
2210                if ((head_deleted && remote_deleted) ||
2211                    (head_deleted && remote && remote_match) ||
2212                    (remote_deleted && head && head_match)) {
2213                        if (index)
2214                                return deleted_entry(index, index, o);
2215                        if (ce && !head_deleted) {
2216                                if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
2217                                        return -1;
2218                        }
2219                        return 0;
2220                }
2221                /*
2222                 * Added in both, identically.
2223                 */
2224                if (no_anc_exists && head && remote && same(head, remote))
2225                        return merged_entry(head, index, o);
2226
2227        }
2228
2229        /* Below are "no merge" cases, which require that the index be
2230         * up-to-date to avoid the files getting overwritten with
2231         * conflict resolution files.
2232         */
2233        if (index) {
2234                if (verify_uptodate(index, o))
2235                        return -1;
2236        }
2237
2238        o->nontrivial_merge = 1;
2239
2240        /* #2, #3, #4, #6, #7, #9, #10, #11. */
2241        count = 0;
2242        if (!head_match || !remote_match) {
2243                for (i = 1; i < o->head_idx; i++) {
2244                        if (stages[i] && stages[i] != o->df_conflict_entry) {
2245                                keep_entry(stages[i], o);
2246                                count++;
2247                                break;
2248                        }
2249                }
2250        }
2251#if DBRT_DEBUG
2252        else {
2253                fprintf(stderr, "read-tree: warning #16 detected\n");
2254                show_stage_entry(stderr, "head   ", stages[head_match]);
2255                show_stage_entry(stderr, "remote ", stages[remote_match]);
2256        }
2257#endif
2258        if (head) { count += keep_entry(head, o); }
2259        if (remote) { count += keep_entry(remote, o); }
2260        return count;
2261}
2262
2263/*
2264 * Two-way merge.
2265 *
2266 * The rule is to "carry forward" what is in the index without losing
2267 * information across a "fast-forward", favoring a successful merge
2268 * over a merge failure when it makes sense.  For details of the
2269 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
2270 *
2271 */
2272int twoway_merge(const struct cache_entry * const *src,
2273                 struct unpack_trees_options *o)
2274{
2275        const struct cache_entry *current = src[0];
2276        const struct cache_entry *oldtree = src[1];
2277        const struct cache_entry *newtree = src[2];
2278
2279        if (o->merge_size != 2)
2280                return error("Cannot do a twoway merge of %d trees",
2281                             o->merge_size);
2282
2283        if (oldtree == o->df_conflict_entry)
2284                oldtree = NULL;
2285        if (newtree == o->df_conflict_entry)
2286                newtree = NULL;
2287
2288        if (current) {
2289                if (current->ce_flags & CE_CONFLICTED) {
2290                        if (same(oldtree, newtree) || o->reset) {
2291                                if (!newtree)
2292                                        return deleted_entry(current, current, o);
2293                                else
2294                                        return merged_entry(newtree, current, o);
2295                        }
2296                        return reject_merge(current, o);
2297                } else if ((!oldtree && !newtree) || /* 4 and 5 */
2298                         (!oldtree && newtree &&
2299                          same(current, newtree)) || /* 6 and 7 */
2300                         (oldtree && newtree &&
2301                          same(oldtree, newtree)) || /* 14 and 15 */
2302                         (oldtree && newtree &&
2303                          !same(oldtree, newtree) && /* 18 and 19 */
2304                          same(current, newtree))) {
2305                        return keep_entry(current, o);
2306                } else if (oldtree && !newtree && same(current, oldtree)) {
2307                        /* 10 or 11 */
2308                        return deleted_entry(oldtree, current, o);
2309                } else if (oldtree && newtree &&
2310                         same(current, oldtree) && !same(current, newtree)) {
2311                        /* 20 or 21 */
2312                        return merged_entry(newtree, current, o);
2313                } else
2314                        return reject_merge(current, o);
2315        }
2316        else if (newtree) {
2317                if (oldtree && !o->initial_checkout) {
2318                        /*
2319                         * deletion of the path was staged;
2320                         */
2321                        if (same(oldtree, newtree))
2322                                return 1;
2323                        return reject_merge(oldtree, o);
2324                }
2325                return merged_entry(newtree, current, o);
2326        }
2327        return deleted_entry(oldtree, current, o);
2328}
2329
2330/*
2331 * Bind merge.
2332 *
2333 * Keep the index entries at stage0, collapse stage1 but make sure
2334 * stage0 does not have anything there.
2335 */
2336int bind_merge(const struct cache_entry * const *src,
2337               struct unpack_trees_options *o)
2338{
2339        const struct cache_entry *old = src[0];
2340        const struct cache_entry *a = src[1];
2341
2342        if (o->merge_size != 1)
2343                return error("Cannot do a bind merge of %d trees",
2344                             o->merge_size);
2345        if (a && old)
2346                return o->quiet ? -1 :
2347                        error(ERRORMSG(o, ERROR_BIND_OVERLAP),
2348                              super_prefixed(a->name),
2349                              super_prefixed(old->name));
2350        if (!a)
2351                return keep_entry(old, o);
2352        else
2353                return merged_entry(a, NULL, o);
2354}
2355
2356/*
2357 * One-way merge.
2358 *
2359 * The rule is:
2360 * - take the stat information from stage0, take the data from stage1
2361 */
2362int oneway_merge(const struct cache_entry * const *src,
2363                 struct unpack_trees_options *o)
2364{
2365        const struct cache_entry *old = src[0];
2366        const struct cache_entry *a = src[1];
2367
2368        if (o->merge_size != 1)
2369                return error("Cannot do a oneway merge of %d trees",
2370                             o->merge_size);
2371
2372        if (!a || a == o->df_conflict_entry)
2373                return deleted_entry(old, old, o);
2374
2375        if (old && same(old, a)) {
2376                int update = 0;
2377                if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
2378                        struct stat st;
2379                        if (lstat(old->name, &st) ||
2380                            ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
2381                                update |= CE_UPDATE;
2382                }
2383                if (o->update && S_ISGITLINK(old->ce_mode) &&
2384                    should_update_submodules() && !verify_uptodate(old, o))
2385                        update |= CE_UPDATE;
2386                add_entry(o, old, update, CE_STAGEMASK);
2387                return 0;
2388        }
2389        return merged_entry(a, old, o);
2390}