unpack-trees.con commit Merge branch 'sg/t0020-conversion-fix' (df19317)
   1#define NO_THE_INDEX_COMPATIBILITY_MACROS
   2#include "cache.h"
   3#include "argv-array.h"
   4#include "repository.h"
   5#include "config.h"
   6#include "dir.h"
   7#include "tree.h"
   8#include "tree-walk.h"
   9#include "cache-tree.h"
  10#include "unpack-trees.h"
  11#include "progress.h"
  12#include "refs.h"
  13#include "attr.h"
  14#include "split-index.h"
  15#include "dir.h"
  16#include "submodule.h"
  17#include "submodule-config.h"
  18#include "fsmonitor.h"
  19#include "object-store.h"
  20#include "fetch-object.h"
  21
  22/*
  23 * Error messages expected by scripts out of plumbing commands such as
  24 * read-tree.  Non-scripted Porcelain is not required to use these messages
  25 * and in fact are encouraged to reword them to better suit their particular
  26 * situation better.  See how "git checkout" and "git merge" replaces
  27 * them using setup_unpack_trees_porcelain(), for example.
  28 */
  29static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
  30        /* ERROR_WOULD_OVERWRITE */
  31        "Entry '%s' would be overwritten by merge. Cannot merge.",
  32
  33        /* ERROR_NOT_UPTODATE_FILE */
  34        "Entry '%s' not uptodate. Cannot merge.",
  35
  36        /* ERROR_NOT_UPTODATE_DIR */
  37        "Updating '%s' would lose untracked files in it",
  38
  39        /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
  40        "Untracked working tree file '%s' would be overwritten by merge.",
  41
  42        /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
  43        "Untracked working tree file '%s' would be removed by merge.",
  44
  45        /* ERROR_BIND_OVERLAP */
  46        "Entry '%s' overlaps with '%s'.  Cannot bind.",
  47
  48        /* ERROR_SPARSE_NOT_UPTODATE_FILE */
  49        "Entry '%s' not uptodate. Cannot update sparse checkout.",
  50
  51        /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
  52        "Working tree file '%s' would be overwritten by sparse checkout update.",
  53
  54        /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
  55        "Working tree file '%s' would be removed by sparse checkout update.",
  56
  57        /* ERROR_WOULD_LOSE_SUBMODULE */
  58        "Submodule '%s' cannot checkout new HEAD.",
  59};
  60
  61#define ERRORMSG(o,type) \
  62        ( ((o) && (o)->msgs[(type)]) \
  63          ? ((o)->msgs[(type)])      \
  64          : (unpack_plumbing_errors[(type)]) )
  65
  66static const char *super_prefixed(const char *path)
  67{
  68        /*
  69         * It is necessary and sufficient to have two static buffers
  70         * here, as the return value of this function is fed to
  71         * error() using the unpack_*_errors[] templates we see above.
  72         */
  73        static struct strbuf buf[2] = {STRBUF_INIT, STRBUF_INIT};
  74        static int super_prefix_len = -1;
  75        static unsigned idx = ARRAY_SIZE(buf) - 1;
  76
  77        if (super_prefix_len < 0) {
  78                const char *super_prefix = get_super_prefix();
  79                if (!super_prefix) {
  80                        super_prefix_len = 0;
  81                } else {
  82                        int i;
  83                        for (i = 0; i < ARRAY_SIZE(buf); i++)
  84                                strbuf_addstr(&buf[i], super_prefix);
  85                        super_prefix_len = buf[0].len;
  86                }
  87        }
  88
  89        if (!super_prefix_len)
  90                return path;
  91
  92        if (++idx >= ARRAY_SIZE(buf))
  93                idx = 0;
  94
  95        strbuf_setlen(&buf[idx], super_prefix_len);
  96        strbuf_addstr(&buf[idx], path);
  97
  98        return buf[idx].buf;
  99}
 100
 101void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
 102                                  const char *cmd)
 103{
 104        int i;
 105        const char **msgs = opts->msgs;
 106        const char *msg;
 107
 108        argv_array_init(&opts->msgs_to_free);
 109
 110        if (!strcmp(cmd, "checkout"))
 111                msg = advice_commit_before_merge
 112                      ? _("Your local changes to the following files would be overwritten by checkout:\n%%s"
 113                          "Please commit your changes or stash them before you switch branches.")
 114                      : _("Your local changes to the following files would be overwritten by checkout:\n%%s");
 115        else if (!strcmp(cmd, "merge"))
 116                msg = advice_commit_before_merge
 117                      ? _("Your local changes to the following files would be overwritten by merge:\n%%s"
 118                          "Please commit your changes or stash them before you merge.")
 119                      : _("Your local changes to the following files would be overwritten by merge:\n%%s");
 120        else
 121                msg = advice_commit_before_merge
 122                      ? _("Your local changes to the following files would be overwritten by %s:\n%%s"
 123                          "Please commit your changes or stash them before you %s.")
 124                      : _("Your local changes to the following files would be overwritten by %s:\n%%s");
 125        msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
 126                argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
 127
 128        msgs[ERROR_NOT_UPTODATE_DIR] =
 129                _("Updating the following directories would lose untracked files in them:\n%s");
 130
 131        if (!strcmp(cmd, "checkout"))
 132                msg = advice_commit_before_merge
 133                      ? _("The following untracked working tree files would be removed by checkout:\n%%s"
 134                          "Please move or remove them before you switch branches.")
 135                      : _("The following untracked working tree files would be removed by checkout:\n%%s");
 136        else if (!strcmp(cmd, "merge"))
 137                msg = advice_commit_before_merge
 138                      ? _("The following untracked working tree files would be removed by merge:\n%%s"
 139                          "Please move or remove them before you merge.")
 140                      : _("The following untracked working tree files would be removed by merge:\n%%s");
 141        else
 142                msg = advice_commit_before_merge
 143                      ? _("The following untracked working tree files would be removed by %s:\n%%s"
 144                          "Please move or remove them before you %s.")
 145                      : _("The following untracked working tree files would be removed by %s:\n%%s");
 146        msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] =
 147                argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
 148
 149        if (!strcmp(cmd, "checkout"))
 150                msg = advice_commit_before_merge
 151                      ? _("The following untracked working tree files would be overwritten by checkout:\n%%s"
 152                          "Please move or remove them before you switch branches.")
 153                      : _("The following untracked working tree files would be overwritten by checkout:\n%%s");
 154        else if (!strcmp(cmd, "merge"))
 155                msg = advice_commit_before_merge
 156                      ? _("The following untracked working tree files would be overwritten by merge:\n%%s"
 157                          "Please move or remove them before you merge.")
 158                      : _("The following untracked working tree files would be overwritten by merge:\n%%s");
 159        else
 160                msg = advice_commit_before_merge
 161                      ? _("The following untracked working tree files would be overwritten by %s:\n%%s"
 162                          "Please move or remove them before you %s.")
 163                      : _("The following untracked working tree files would be overwritten by %s:\n%%s");
 164        msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] =
 165                argv_array_pushf(&opts->msgs_to_free, msg, cmd, cmd);
 166
 167        /*
 168         * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
 169         * cannot easily display it as a list.
 170         */
 171        msgs[ERROR_BIND_OVERLAP] = _("Entry '%s' overlaps with '%s'.  Cannot bind.");
 172
 173        msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
 174                _("Cannot update sparse checkout: the following entries are not up to date:\n%s");
 175        msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
 176                _("The following working tree files would be overwritten by sparse checkout update:\n%s");
 177        msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
 178                _("The following working tree files would be removed by sparse checkout update:\n%s");
 179        msgs[ERROR_WOULD_LOSE_SUBMODULE] =
 180                _("Cannot update submodule:\n%s");
 181
 182        opts->show_all_errors = 1;
 183        /* rejected paths may not have a static buffer */
 184        for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
 185                opts->unpack_rejects[i].strdup_strings = 1;
 186}
 187
 188void clear_unpack_trees_porcelain(struct unpack_trees_options *opts)
 189{
 190        argv_array_clear(&opts->msgs_to_free);
 191        memset(opts->msgs, 0, sizeof(opts->msgs));
 192}
 193
 194static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
 195                         unsigned int set, unsigned int clear)
 196{
 197        clear |= CE_HASHED;
 198
 199        if (set & CE_REMOVE)
 200                set |= CE_WT_REMOVE;
 201
 202        ce->ce_flags = (ce->ce_flags & ~clear) | set;
 203        return add_index_entry(&o->result, ce,
 204                               ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 205}
 206
 207static void add_entry(struct unpack_trees_options *o,
 208                      const struct cache_entry *ce,
 209                      unsigned int set, unsigned int clear)
 210{
 211        do_add_entry(o, dup_cache_entry(ce, &o->result), set, clear);
 212}
 213
 214/*
 215 * add error messages on path <path>
 216 * corresponding to the type <e> with the message <msg>
 217 * indicating if it should be display in porcelain or not
 218 */
 219static int add_rejected_path(struct unpack_trees_options *o,
 220                             enum unpack_trees_error_types e,
 221                             const char *path)
 222{
 223        if (!o->show_all_errors)
 224                return error(ERRORMSG(o, e), super_prefixed(path));
 225
 226        /*
 227         * Otherwise, insert in a list for future display by
 228         * display_error_msgs()
 229         */
 230        string_list_append(&o->unpack_rejects[e], path);
 231        return -1;
 232}
 233
 234/*
 235 * display all the error messages stored in a nice way
 236 */
 237static void display_error_msgs(struct unpack_trees_options *o)
 238{
 239        int e, i;
 240        int something_displayed = 0;
 241        for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
 242                struct string_list *rejects = &o->unpack_rejects[e];
 243                if (rejects->nr > 0) {
 244                        struct strbuf path = STRBUF_INIT;
 245                        something_displayed = 1;
 246                        for (i = 0; i < rejects->nr; i++)
 247                                strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
 248                        error(ERRORMSG(o, e), super_prefixed(path.buf));
 249                        strbuf_release(&path);
 250                }
 251                string_list_clear(rejects, 0);
 252        }
 253        if (something_displayed)
 254                fprintf(stderr, _("Aborting\n"));
 255}
 256
 257static int check_submodule_move_head(const struct cache_entry *ce,
 258                                     const char *old_id,
 259                                     const char *new_id,
 260                                     struct unpack_trees_options *o)
 261{
 262        unsigned flags = SUBMODULE_MOVE_HEAD_DRY_RUN;
 263        const struct submodule *sub = submodule_from_ce(ce);
 264
 265        if (!sub)
 266                return 0;
 267
 268        if (o->reset)
 269                flags |= SUBMODULE_MOVE_HEAD_FORCE;
 270
 271        if (submodule_move_head(ce->name, old_id, new_id, flags))
 272                return o->gently ? -1 :
 273                                   add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
 274        return 0;
 275}
 276
 277/*
 278 * Preform the loading of the repository's gitmodules file.  This function is
 279 * used by 'check_update()' to perform loading of the gitmodules file in two
 280 * differnt situations:
 281 * (1) before removing entries from the working tree if the gitmodules file has
 282 *     been marked for removal.  This situation is specified by 'state' == NULL.
 283 * (2) before checking out entries to the working tree if the gitmodules file
 284 *     has been marked for update.  This situation is specified by 'state' != NULL.
 285 */
 286static void load_gitmodules_file(struct index_state *index,
 287                                 struct checkout *state)
 288{
 289        int pos = index_name_pos(index, GITMODULES_FILE, strlen(GITMODULES_FILE));
 290
 291        if (pos >= 0) {
 292                struct cache_entry *ce = index->cache[pos];
 293                if (!state && ce->ce_flags & CE_WT_REMOVE) {
 294                        repo_read_gitmodules(the_repository);
 295                } else if (state && (ce->ce_flags & CE_UPDATE)) {
 296                        submodule_free(the_repository);
 297                        checkout_entry(ce, state, NULL);
 298                        repo_read_gitmodules(the_repository);
 299                }
 300        }
 301}
 302
 303/*
 304 * Unlink the last component and schedule the leading directories for
 305 * removal, such that empty directories get removed.
 306 */
 307static void unlink_entry(const struct cache_entry *ce)
 308{
 309        const struct submodule *sub = submodule_from_ce(ce);
 310        if (sub) {
 311                /* state.force is set at the caller. */
 312                submodule_move_head(ce->name, "HEAD", NULL,
 313                                    SUBMODULE_MOVE_HEAD_FORCE);
 314        }
 315        if (!check_leading_path(ce->name, ce_namelen(ce)))
 316                return;
 317        if (remove_or_warn(ce->ce_mode, ce->name))
 318                return;
 319        schedule_dir_for_removal(ce->name, ce_namelen(ce));
 320}
 321
 322static struct progress *get_progress(struct unpack_trees_options *o)
 323{
 324        unsigned cnt = 0, total = 0;
 325        struct index_state *index = &o->result;
 326
 327        if (!o->update || !o->verbose_update)
 328                return NULL;
 329
 330        for (; cnt < index->cache_nr; cnt++) {
 331                const struct cache_entry *ce = index->cache[cnt];
 332                if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
 333                        total++;
 334        }
 335
 336        return start_delayed_progress(_("Checking out files"), total);
 337}
 338
 339static int check_updates(struct unpack_trees_options *o)
 340{
 341        unsigned cnt = 0;
 342        int errs = 0;
 343        struct progress *progress = NULL;
 344        struct index_state *index = &o->result;
 345        struct checkout state = CHECKOUT_INIT;
 346        int i;
 347
 348        state.force = 1;
 349        state.quiet = 1;
 350        state.refresh_cache = 1;
 351        state.istate = index;
 352
 353        progress = get_progress(o);
 354
 355        if (o->update)
 356                git_attr_set_direction(GIT_ATTR_CHECKOUT);
 357
 358        if (should_update_submodules() && o->update && !o->dry_run)
 359                load_gitmodules_file(index, NULL);
 360
 361        for (i = 0; i < index->cache_nr; i++) {
 362                const struct cache_entry *ce = index->cache[i];
 363
 364                if (ce->ce_flags & CE_WT_REMOVE) {
 365                        display_progress(progress, ++cnt);
 366                        if (o->update && !o->dry_run)
 367                                unlink_entry(ce);
 368                }
 369        }
 370        remove_marked_cache_entries(index);
 371        remove_scheduled_dirs();
 372
 373        if (should_update_submodules() && o->update && !o->dry_run)
 374                load_gitmodules_file(index, &state);
 375
 376        enable_delayed_checkout(&state);
 377        if (repository_format_partial_clone && o->update && !o->dry_run) {
 378                /*
 379                 * Prefetch the objects that are to be checked out in the loop
 380                 * below.
 381                 */
 382                struct oid_array to_fetch = OID_ARRAY_INIT;
 383                int fetch_if_missing_store = fetch_if_missing;
 384                fetch_if_missing = 0;
 385                for (i = 0; i < index->cache_nr; i++) {
 386                        struct cache_entry *ce = index->cache[i];
 387                        if ((ce->ce_flags & CE_UPDATE) &&
 388                            !S_ISGITLINK(ce->ce_mode)) {
 389                                if (!has_object_file(&ce->oid))
 390                                        oid_array_append(&to_fetch, &ce->oid);
 391                        }
 392                }
 393                if (to_fetch.nr)
 394                        fetch_objects(repository_format_partial_clone,
 395                                      &to_fetch);
 396                fetch_if_missing = fetch_if_missing_store;
 397                oid_array_clear(&to_fetch);
 398        }
 399        for (i = 0; i < index->cache_nr; i++) {
 400                struct cache_entry *ce = index->cache[i];
 401
 402                if (ce->ce_flags & CE_UPDATE) {
 403                        if (ce->ce_flags & CE_WT_REMOVE)
 404                                BUG("both update and delete flags are set on %s",
 405                                    ce->name);
 406                        display_progress(progress, ++cnt);
 407                        ce->ce_flags &= ~CE_UPDATE;
 408                        if (o->update && !o->dry_run) {
 409                                errs |= checkout_entry(ce, &state, NULL);
 410                        }
 411                }
 412        }
 413        stop_progress(&progress);
 414        errs |= finish_delayed_checkout(&state);
 415        if (o->update)
 416                git_attr_set_direction(GIT_ATTR_CHECKIN);
 417        return errs != 0;
 418}
 419
 420static int verify_uptodate_sparse(const struct cache_entry *ce,
 421                                  struct unpack_trees_options *o);
 422static int verify_absent_sparse(const struct cache_entry *ce,
 423                                enum unpack_trees_error_types,
 424                                struct unpack_trees_options *o);
 425
 426static int apply_sparse_checkout(struct index_state *istate,
 427                                 struct cache_entry *ce,
 428                                 struct unpack_trees_options *o)
 429{
 430        int was_skip_worktree = ce_skip_worktree(ce);
 431
 432        if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
 433                ce->ce_flags |= CE_SKIP_WORKTREE;
 434        else
 435                ce->ce_flags &= ~CE_SKIP_WORKTREE;
 436        if (was_skip_worktree != ce_skip_worktree(ce)) {
 437                ce->ce_flags |= CE_UPDATE_IN_BASE;
 438                mark_fsmonitor_invalid(istate, ce);
 439                istate->cache_changed |= CE_ENTRY_CHANGED;
 440        }
 441
 442        /*
 443         * if (!was_skip_worktree && !ce_skip_worktree()) {
 444         *      This is perfectly normal. Move on;
 445         * }
 446         */
 447
 448        /*
 449         * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
 450         * area as a result of ce_skip_worktree() shortcuts in
 451         * verify_absent() and verify_uptodate().
 452         * Make sure they don't modify worktree if they are already
 453         * outside checkout area
 454         */
 455        if (was_skip_worktree && ce_skip_worktree(ce)) {
 456                ce->ce_flags &= ~CE_UPDATE;
 457
 458                /*
 459                 * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
 460                 * on to get that file removed from both index and worktree.
 461                 * If that file is already outside worktree area, don't
 462                 * bother remove it.
 463                 */
 464                if (ce->ce_flags & CE_REMOVE)
 465                        ce->ce_flags &= ~CE_WT_REMOVE;
 466        }
 467
 468        if (!was_skip_worktree && ce_skip_worktree(ce)) {
 469                /*
 470                 * If CE_UPDATE is set, verify_uptodate() must be called already
 471                 * also stat info may have lost after merged_entry() so calling
 472                 * verify_uptodate() again may fail
 473                 */
 474                if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
 475                        return -1;
 476                ce->ce_flags |= CE_WT_REMOVE;
 477                ce->ce_flags &= ~CE_UPDATE;
 478        }
 479        if (was_skip_worktree && !ce_skip_worktree(ce)) {
 480                if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
 481                        return -1;
 482                ce->ce_flags |= CE_UPDATE;
 483        }
 484        return 0;
 485}
 486
 487static inline int call_unpack_fn(const struct cache_entry * const *src,
 488                                 struct unpack_trees_options *o)
 489{
 490        int ret = o->fn(src, o);
 491        if (ret > 0)
 492                ret = 0;
 493        return ret;
 494}
 495
 496static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
 497{
 498        ce->ce_flags |= CE_UNPACKED;
 499
 500        if (o->cache_bottom < o->src_index->cache_nr &&
 501            o->src_index->cache[o->cache_bottom] == ce) {
 502                int bottom = o->cache_bottom;
 503                while (bottom < o->src_index->cache_nr &&
 504                       o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
 505                        bottom++;
 506                o->cache_bottom = bottom;
 507        }
 508}
 509
 510static void mark_all_ce_unused(struct index_state *index)
 511{
 512        int i;
 513        for (i = 0; i < index->cache_nr; i++)
 514                index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
 515}
 516
 517static int locate_in_src_index(const struct cache_entry *ce,
 518                               struct unpack_trees_options *o)
 519{
 520        struct index_state *index = o->src_index;
 521        int len = ce_namelen(ce);
 522        int pos = index_name_pos(index, ce->name, len);
 523        if (pos < 0)
 524                pos = -1 - pos;
 525        return pos;
 526}
 527
 528/*
 529 * We call unpack_index_entry() with an unmerged cache entry
 530 * only in diff-index, and it wants a single callback.  Skip
 531 * the other unmerged entry with the same name.
 532 */
 533static void mark_ce_used_same_name(struct cache_entry *ce,
 534                                   struct unpack_trees_options *o)
 535{
 536        struct index_state *index = o->src_index;
 537        int len = ce_namelen(ce);
 538        int pos;
 539
 540        for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
 541                struct cache_entry *next = index->cache[pos];
 542                if (len != ce_namelen(next) ||
 543                    memcmp(ce->name, next->name, len))
 544                        break;
 545                mark_ce_used(next, o);
 546        }
 547}
 548
 549static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
 550{
 551        const struct index_state *index = o->src_index;
 552        int pos = o->cache_bottom;
 553
 554        while (pos < index->cache_nr) {
 555                struct cache_entry *ce = index->cache[pos];
 556                if (!(ce->ce_flags & CE_UNPACKED))
 557                        return ce;
 558                pos++;
 559        }
 560        return NULL;
 561}
 562
 563static void add_same_unmerged(const struct cache_entry *ce,
 564                              struct unpack_trees_options *o)
 565{
 566        struct index_state *index = o->src_index;
 567        int len = ce_namelen(ce);
 568        int pos = index_name_pos(index, ce->name, len);
 569
 570        if (0 <= pos)
 571                die("programming error in a caller of mark_ce_used_same_name");
 572        for (pos = -pos - 1; pos < index->cache_nr; pos++) {
 573                struct cache_entry *next = index->cache[pos];
 574                if (len != ce_namelen(next) ||
 575                    memcmp(ce->name, next->name, len))
 576                        break;
 577                add_entry(o, next, 0, 0);
 578                mark_ce_used(next, o);
 579        }
 580}
 581
 582static int unpack_index_entry(struct cache_entry *ce,
 583                              struct unpack_trees_options *o)
 584{
 585        const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 586        int ret;
 587
 588        src[0] = ce;
 589
 590        mark_ce_used(ce, o);
 591        if (ce_stage(ce)) {
 592                if (o->skip_unmerged) {
 593                        add_entry(o, ce, 0, 0);
 594                        return 0;
 595                }
 596        }
 597        ret = call_unpack_fn(src, o);
 598        if (ce_stage(ce))
 599                mark_ce_used_same_name(ce, o);
 600        return ret;
 601}
 602
 603static int find_cache_pos(struct traverse_info *, const struct name_entry *);
 604
 605static void restore_cache_bottom(struct traverse_info *info, int bottom)
 606{
 607        struct unpack_trees_options *o = info->data;
 608
 609        if (o->diff_index_cached)
 610                return;
 611        o->cache_bottom = bottom;
 612}
 613
 614static int switch_cache_bottom(struct traverse_info *info)
 615{
 616        struct unpack_trees_options *o = info->data;
 617        int ret, pos;
 618
 619        if (o->diff_index_cached)
 620                return 0;
 621        ret = o->cache_bottom;
 622        pos = find_cache_pos(info->prev, &info->name);
 623
 624        if (pos < -1)
 625                o->cache_bottom = -2 - pos;
 626        else if (pos < 0)
 627                o->cache_bottom = o->src_index->cache_nr;
 628        return ret;
 629}
 630
 631static inline int are_same_oid(struct name_entry *name_j, struct name_entry *name_k)
 632{
 633        return name_j->oid && name_k->oid && !oidcmp(name_j->oid, name_k->oid);
 634}
 635
 636static int traverse_trees_recursive(int n, unsigned long dirmask,
 637                                    unsigned long df_conflicts,
 638                                    struct name_entry *names,
 639                                    struct traverse_info *info)
 640{
 641        int i, ret, bottom;
 642        int nr_buf = 0;
 643        struct tree_desc t[MAX_UNPACK_TREES];
 644        void *buf[MAX_UNPACK_TREES];
 645        struct traverse_info newinfo;
 646        struct name_entry *p;
 647
 648        p = names;
 649        while (!p->mode)
 650                p++;
 651
 652        newinfo = *info;
 653        newinfo.prev = info;
 654        newinfo.pathspec = info->pathspec;
 655        newinfo.name = *p;
 656        newinfo.pathlen += tree_entry_len(p) + 1;
 657        newinfo.df_conflicts |= df_conflicts;
 658
 659        /*
 660         * Fetch the tree from the ODB for each peer directory in the
 661         * n commits.
 662         *
 663         * For 2- and 3-way traversals, we try to avoid hitting the
 664         * ODB twice for the same OID.  This should yield a nice speed
 665         * up in checkouts and merges when the commits are similar.
 666         *
 667         * We don't bother doing the full O(n^2) search for larger n,
 668         * because wider traversals don't happen that often and we
 669         * avoid the search setup.
 670         *
 671         * When 2 peer OIDs are the same, we just copy the tree
 672         * descriptor data.  This implicitly borrows the buffer
 673         * data from the earlier cell.
 674         */
 675        for (i = 0; i < n; i++, dirmask >>= 1) {
 676                if (i > 0 && are_same_oid(&names[i], &names[i - 1]))
 677                        t[i] = t[i - 1];
 678                else if (i > 1 && are_same_oid(&names[i], &names[i - 2]))
 679                        t[i] = t[i - 2];
 680                else {
 681                        const struct object_id *oid = NULL;
 682                        if (dirmask & 1)
 683                                oid = names[i].oid;
 684                        buf[nr_buf++] = fill_tree_descriptor(t + i, oid);
 685                }
 686        }
 687
 688        bottom = switch_cache_bottom(&newinfo);
 689        ret = traverse_trees(n, t, &newinfo);
 690        restore_cache_bottom(&newinfo, bottom);
 691
 692        for (i = 0; i < nr_buf; i++)
 693                free(buf[i]);
 694
 695        return ret;
 696}
 697
 698/*
 699 * Compare the traverse-path to the cache entry without actually
 700 * having to generate the textual representation of the traverse
 701 * path.
 702 *
 703 * NOTE! This *only* compares up to the size of the traverse path
 704 * itself - the caller needs to do the final check for the cache
 705 * entry having more data at the end!
 706 */
 707static int do_compare_entry_piecewise(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 708{
 709        int len, pathlen, ce_len;
 710        const char *ce_name;
 711
 712        if (info->prev) {
 713                int cmp = do_compare_entry_piecewise(ce, info->prev,
 714                                                     &info->name);
 715                if (cmp)
 716                        return cmp;
 717        }
 718        pathlen = info->pathlen;
 719        ce_len = ce_namelen(ce);
 720
 721        /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 722        if (ce_len < pathlen)
 723                return -1;
 724
 725        ce_len -= pathlen;
 726        ce_name = ce->name + pathlen;
 727
 728        len = tree_entry_len(n);
 729        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 730}
 731
 732static int do_compare_entry(const struct cache_entry *ce,
 733                            const struct traverse_info *info,
 734                            const struct name_entry *n)
 735{
 736        int len, pathlen, ce_len;
 737        const char *ce_name;
 738        int cmp;
 739
 740        /*
 741         * If we have not precomputed the traverse path, it is quicker
 742         * to avoid doing so.  But if we have precomputed it,
 743         * it is quicker to use the precomputed version.
 744         */
 745        if (!info->traverse_path)
 746                return do_compare_entry_piecewise(ce, info, n);
 747
 748        cmp = strncmp(ce->name, info->traverse_path, info->pathlen);
 749        if (cmp)
 750                return cmp;
 751
 752        pathlen = info->pathlen;
 753        ce_len = ce_namelen(ce);
 754
 755        if (ce_len < pathlen)
 756                return -1;
 757
 758        ce_len -= pathlen;
 759        ce_name = ce->name + pathlen;
 760
 761        len = tree_entry_len(n);
 762        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 763}
 764
 765static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 766{
 767        int cmp = do_compare_entry(ce, info, n);
 768        if (cmp)
 769                return cmp;
 770
 771        /*
 772         * Even if the beginning compared identically, the ce should
 773         * compare as bigger than a directory leading up to it!
 774         */
 775        return ce_namelen(ce) > traverse_path_len(info, n);
 776}
 777
 778static int ce_in_traverse_path(const struct cache_entry *ce,
 779                               const struct traverse_info *info)
 780{
 781        if (!info->prev)
 782                return 1;
 783        if (do_compare_entry(ce, info->prev, &info->name))
 784                return 0;
 785        /*
 786         * If ce (blob) is the same name as the path (which is a tree
 787         * we will be descending into), it won't be inside it.
 788         */
 789        return (info->pathlen < ce_namelen(ce));
 790}
 791
 792static struct cache_entry *create_ce_entry(const struct traverse_info *info,
 793        const struct name_entry *n,
 794        int stage,
 795        struct index_state *istate,
 796        int is_transient)
 797{
 798        int len = traverse_path_len(info, n);
 799        struct cache_entry *ce =
 800                is_transient ?
 801                make_empty_transient_cache_entry(len) :
 802                make_empty_cache_entry(istate, len);
 803
 804        ce->ce_mode = create_ce_mode(n->mode);
 805        ce->ce_flags = create_ce_flags(stage);
 806        ce->ce_namelen = len;
 807        oidcpy(&ce->oid, n->oid);
 808        make_traverse_path(ce->name, info, n);
 809
 810        return ce;
 811}
 812
 813static int unpack_nondirectories(int n, unsigned long mask,
 814                                 unsigned long dirmask,
 815                                 struct cache_entry **src,
 816                                 const struct name_entry *names,
 817                                 const struct traverse_info *info)
 818{
 819        int i;
 820        struct unpack_trees_options *o = info->data;
 821        unsigned long conflicts = info->df_conflicts | dirmask;
 822
 823        /* Do we have *only* directories? Nothing to do */
 824        if (mask == dirmask && !src[0])
 825                return 0;
 826
 827        /*
 828         * Ok, we've filled in up to any potential index entry in src[0],
 829         * now do the rest.
 830         */
 831        for (i = 0; i < n; i++) {
 832                int stage;
 833                unsigned int bit = 1ul << i;
 834                if (conflicts & bit) {
 835                        src[i + o->merge] = o->df_conflict_entry;
 836                        continue;
 837                }
 838                if (!(mask & bit))
 839                        continue;
 840                if (!o->merge)
 841                        stage = 0;
 842                else if (i + 1 < o->head_idx)
 843                        stage = 1;
 844                else if (i + 1 > o->head_idx)
 845                        stage = 3;
 846                else
 847                        stage = 2;
 848
 849                /*
 850                 * If the merge bit is set, then the cache entries are
 851                 * discarded in the following block.  In this case,
 852                 * construct "transient" cache_entries, as they are
 853                 * not stored in the index.  otherwise construct the
 854                 * cache entry from the index aware logic.
 855                 */
 856                src[i + o->merge] = create_ce_entry(info, names + i, stage, &o->result, o->merge);
 857        }
 858
 859        if (o->merge) {
 860                int rc = call_unpack_fn((const struct cache_entry * const *)src,
 861                                        o);
 862                for (i = 0; i < n; i++) {
 863                        struct cache_entry *ce = src[i + o->merge];
 864                        if (ce != o->df_conflict_entry)
 865                                discard_cache_entry(ce);
 866                }
 867                return rc;
 868        }
 869
 870        for (i = 0; i < n; i++)
 871                if (src[i] && src[i] != o->df_conflict_entry)
 872                        if (do_add_entry(o, src[i], 0, 0))
 873                                return -1;
 874
 875        return 0;
 876}
 877
 878static int unpack_failed(struct unpack_trees_options *o, const char *message)
 879{
 880        discard_index(&o->result);
 881        if (!o->gently && !o->exiting_early) {
 882                if (message)
 883                        return error("%s", message);
 884                return -1;
 885        }
 886        return -1;
 887}
 888
 889/*
 890 * The tree traversal is looking at name p.  If we have a matching entry,
 891 * return it.  If name p is a directory in the index, do not return
 892 * anything, as we will want to match it when the traversal descends into
 893 * the directory.
 894 */
 895static int find_cache_pos(struct traverse_info *info,
 896                          const struct name_entry *p)
 897{
 898        int pos;
 899        struct unpack_trees_options *o = info->data;
 900        struct index_state *index = o->src_index;
 901        int pfxlen = info->pathlen;
 902        int p_len = tree_entry_len(p);
 903
 904        for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
 905                const struct cache_entry *ce = index->cache[pos];
 906                const char *ce_name, *ce_slash;
 907                int cmp, ce_len;
 908
 909                if (ce->ce_flags & CE_UNPACKED) {
 910                        /*
 911                         * cache_bottom entry is already unpacked, so
 912                         * we can never match it; don't check it
 913                         * again.
 914                         */
 915                        if (pos == o->cache_bottom)
 916                                ++o->cache_bottom;
 917                        continue;
 918                }
 919                if (!ce_in_traverse_path(ce, info)) {
 920                        /*
 921                         * Check if we can skip future cache checks
 922                         * (because we're already past all possible
 923                         * entries in the traverse path).
 924                         */
 925                        if (info->traverse_path) {
 926                                if (strncmp(ce->name, info->traverse_path,
 927                                            info->pathlen) > 0)
 928                                        break;
 929                        }
 930                        continue;
 931                }
 932                ce_name = ce->name + pfxlen;
 933                ce_slash = strchr(ce_name, '/');
 934                if (ce_slash)
 935                        ce_len = ce_slash - ce_name;
 936                else
 937                        ce_len = ce_namelen(ce) - pfxlen;
 938                cmp = name_compare(p->path, p_len, ce_name, ce_len);
 939                /*
 940                 * Exact match; if we have a directory we need to
 941                 * delay returning it.
 942                 */
 943                if (!cmp)
 944                        return ce_slash ? -2 - pos : pos;
 945                if (0 < cmp)
 946                        continue; /* keep looking */
 947                /*
 948                 * ce_name sorts after p->path; could it be that we
 949                 * have files under p->path directory in the index?
 950                 * E.g.  ce_name == "t-i", and p->path == "t"; we may
 951                 * have "t/a" in the index.
 952                 */
 953                if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
 954                    ce_name[p_len] < '/')
 955                        continue; /* keep looking */
 956                break;
 957        }
 958        return -1;
 959}
 960
 961static struct cache_entry *find_cache_entry(struct traverse_info *info,
 962                                            const struct name_entry *p)
 963{
 964        int pos = find_cache_pos(info, p);
 965        struct unpack_trees_options *o = info->data;
 966
 967        if (0 <= pos)
 968                return o->src_index->cache[pos];
 969        else
 970                return NULL;
 971}
 972
 973static void debug_path(struct traverse_info *info)
 974{
 975        if (info->prev) {
 976                debug_path(info->prev);
 977                if (*info->prev->name.path)
 978                        putchar('/');
 979        }
 980        printf("%s", info->name.path);
 981}
 982
 983static void debug_name_entry(int i, struct name_entry *n)
 984{
 985        printf("ent#%d %06o %s\n", i,
 986               n->path ? n->mode : 0,
 987               n->path ? n->path : "(missing)");
 988}
 989
 990static void debug_unpack_callback(int n,
 991                                  unsigned long mask,
 992                                  unsigned long dirmask,
 993                                  struct name_entry *names,
 994                                  struct traverse_info *info)
 995{
 996        int i;
 997        printf("* unpack mask %lu, dirmask %lu, cnt %d ",
 998               mask, dirmask, n);
 999        debug_path(info);
1000        putchar('\n');
1001        for (i = 0; i < n; i++)
1002                debug_name_entry(i, names + i);
1003}
1004
1005static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
1006{
1007        struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
1008        struct unpack_trees_options *o = info->data;
1009        const struct name_entry *p = names;
1010
1011        /* Find first entry with a real name (we could use "mask" too) */
1012        while (!p->mode)
1013                p++;
1014
1015        if (o->debug_unpack)
1016                debug_unpack_callback(n, mask, dirmask, names, info);
1017
1018        /* Are we supposed to look at the index too? */
1019        if (o->merge) {
1020                while (1) {
1021                        int cmp;
1022                        struct cache_entry *ce;
1023
1024                        if (o->diff_index_cached)
1025                                ce = next_cache_entry(o);
1026                        else
1027                                ce = find_cache_entry(info, p);
1028
1029                        if (!ce)
1030                                break;
1031                        cmp = compare_entry(ce, info, p);
1032                        if (cmp < 0) {
1033                                if (unpack_index_entry(ce, o) < 0)
1034                                        return unpack_failed(o, NULL);
1035                                continue;
1036                        }
1037                        if (!cmp) {
1038                                if (ce_stage(ce)) {
1039                                        /*
1040                                         * If we skip unmerged index
1041                                         * entries, we'll skip this
1042                                         * entry *and* the tree
1043                                         * entries associated with it!
1044                                         */
1045                                        if (o->skip_unmerged) {
1046                                                add_same_unmerged(ce, o);
1047                                                return mask;
1048                                        }
1049                                }
1050                                src[0] = ce;
1051                        }
1052                        break;
1053                }
1054        }
1055
1056        if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
1057                return -1;
1058
1059        if (o->merge && src[0]) {
1060                if (ce_stage(src[0]))
1061                        mark_ce_used_same_name(src[0], o);
1062                else
1063                        mark_ce_used(src[0], o);
1064        }
1065
1066        /* Now handle any directories.. */
1067        if (dirmask) {
1068                /* special case: "diff-index --cached" looking at a tree */
1069                if (o->diff_index_cached &&
1070                    n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
1071                        int matches;
1072                        matches = cache_tree_matches_traversal(o->src_index->cache_tree,
1073                                                               names, info);
1074                        /*
1075                         * Everything under the name matches; skip the
1076                         * entire hierarchy.  diff_index_cached codepath
1077                         * special cases D/F conflicts in such a way that
1078                         * it does not do any look-ahead, so this is safe.
1079                         */
1080                        if (matches) {
1081                                o->cache_bottom += matches;
1082                                return mask;
1083                        }
1084                }
1085
1086                if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
1087                                             names, info) < 0)
1088                        return -1;
1089                return mask;
1090        }
1091
1092        return mask;
1093}
1094
1095static int clear_ce_flags_1(struct index_state *istate,
1096                            struct cache_entry **cache, int nr,
1097                            struct strbuf *prefix,
1098                            int select_mask, int clear_mask,
1099                            struct exclude_list *el, int defval);
1100
1101/* Whole directory matching */
1102static int clear_ce_flags_dir(struct index_state *istate,
1103                              struct cache_entry **cache, int nr,
1104                              struct strbuf *prefix,
1105                              char *basename,
1106                              int select_mask, int clear_mask,
1107                              struct exclude_list *el, int defval)
1108{
1109        struct cache_entry **cache_end;
1110        int dtype = DT_DIR;
1111        int ret = is_excluded_from_list(prefix->buf, prefix->len,
1112                                        basename, &dtype, el, istate);
1113        int rc;
1114
1115        strbuf_addch(prefix, '/');
1116
1117        /* If undecided, use matching result of parent dir in defval */
1118        if (ret < 0)
1119                ret = defval;
1120
1121        for (cache_end = cache; cache_end != cache + nr; cache_end++) {
1122                struct cache_entry *ce = *cache_end;
1123                if (strncmp(ce->name, prefix->buf, prefix->len))
1124                        break;
1125        }
1126
1127        /*
1128         * TODO: check el, if there are no patterns that may conflict
1129         * with ret (iow, we know in advance the incl/excl
1130         * decision for the entire directory), clear flag here without
1131         * calling clear_ce_flags_1(). That function will call
1132         * the expensive is_excluded_from_list() on every entry.
1133         */
1134        rc = clear_ce_flags_1(istate, cache, cache_end - cache,
1135                              prefix,
1136                              select_mask, clear_mask,
1137                              el, ret);
1138        strbuf_setlen(prefix, prefix->len - 1);
1139        return rc;
1140}
1141
1142/*
1143 * Traverse the index, find every entry that matches according to
1144 * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
1145 * number of traversed entries.
1146 *
1147 * If select_mask is non-zero, only entries whose ce_flags has on of
1148 * those bits enabled are traversed.
1149 *
1150 * cache        : pointer to an index entry
1151 * prefix_len   : an offset to its path
1152 *
1153 * The current path ("prefix") including the trailing '/' is
1154 *   cache[0]->name[0..(prefix_len-1)]
1155 * Top level path has prefix_len zero.
1156 */
1157static int clear_ce_flags_1(struct index_state *istate,
1158                            struct cache_entry **cache, int nr,
1159                            struct strbuf *prefix,
1160                            int select_mask, int clear_mask,
1161                            struct exclude_list *el, int defval)
1162{
1163        struct cache_entry **cache_end = cache + nr;
1164
1165        /*
1166         * Process all entries that have the given prefix and meet
1167         * select_mask condition
1168         */
1169        while(cache != cache_end) {
1170                struct cache_entry *ce = *cache;
1171                const char *name, *slash;
1172                int len, dtype, ret;
1173
1174                if (select_mask && !(ce->ce_flags & select_mask)) {
1175                        cache++;
1176                        continue;
1177                }
1178
1179                if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
1180                        break;
1181
1182                name = ce->name + prefix->len;
1183                slash = strchr(name, '/');
1184
1185                /* If it's a directory, try whole directory match first */
1186                if (slash) {
1187                        int processed;
1188
1189                        len = slash - name;
1190                        strbuf_add(prefix, name, len);
1191
1192                        processed = clear_ce_flags_dir(istate, cache, cache_end - cache,
1193                                                       prefix,
1194                                                       prefix->buf + prefix->len - len,
1195                                                       select_mask, clear_mask,
1196                                                       el, defval);
1197
1198                        /* clear_c_f_dir eats a whole dir already? */
1199                        if (processed) {
1200                                cache += processed;
1201                                strbuf_setlen(prefix, prefix->len - len);
1202                                continue;
1203                        }
1204
1205                        strbuf_addch(prefix, '/');
1206                        cache += clear_ce_flags_1(istate, cache, cache_end - cache,
1207                                                  prefix,
1208                                                  select_mask, clear_mask, el, defval);
1209                        strbuf_setlen(prefix, prefix->len - len - 1);
1210                        continue;
1211                }
1212
1213                /* Non-directory */
1214                dtype = ce_to_dtype(ce);
1215                ret = is_excluded_from_list(ce->name, ce_namelen(ce),
1216                                            name, &dtype, el, istate);
1217                if (ret < 0)
1218                        ret = defval;
1219                if (ret > 0)
1220                        ce->ce_flags &= ~clear_mask;
1221                cache++;
1222        }
1223        return nr - (cache_end - cache);
1224}
1225
1226static int clear_ce_flags(struct index_state *istate,
1227                          int select_mask, int clear_mask,
1228                          struct exclude_list *el)
1229{
1230        static struct strbuf prefix = STRBUF_INIT;
1231
1232        strbuf_reset(&prefix);
1233
1234        return clear_ce_flags_1(istate,
1235                                istate->cache,
1236                                istate->cache_nr,
1237                                &prefix,
1238                                select_mask, clear_mask,
1239                                el, 0);
1240}
1241
1242/*
1243 * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
1244 */
1245static void mark_new_skip_worktree(struct exclude_list *el,
1246                                   struct index_state *istate,
1247                                   int select_flag, int skip_wt_flag)
1248{
1249        int i;
1250
1251        /*
1252         * 1. Pretend the narrowest worktree: only unmerged entries
1253         * are checked out
1254         */
1255        for (i = 0; i < istate->cache_nr; i++) {
1256                struct cache_entry *ce = istate->cache[i];
1257
1258                if (select_flag && !(ce->ce_flags & select_flag))
1259                        continue;
1260
1261                if (!ce_stage(ce) && !(ce->ce_flags & CE_CONFLICTED))
1262                        ce->ce_flags |= skip_wt_flag;
1263                else
1264                        ce->ce_flags &= ~skip_wt_flag;
1265        }
1266
1267        /*
1268         * 2. Widen worktree according to sparse-checkout file.
1269         * Matched entries will have skip_wt_flag cleared (i.e. "in")
1270         */
1271        clear_ce_flags(istate, select_flag, skip_wt_flag, el);
1272}
1273
1274static int verify_absent(const struct cache_entry *,
1275                         enum unpack_trees_error_types,
1276                         struct unpack_trees_options *);
1277/*
1278 * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1279 * resulting index, -2 on failure to reflect the changes to the work tree.
1280 *
1281 * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1282 */
1283int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1284{
1285        int i, ret;
1286        static struct cache_entry *dfc;
1287        struct exclude_list el;
1288
1289        if (len > MAX_UNPACK_TREES)
1290                die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1291
1292        memset(&el, 0, sizeof(el));
1293        if (!core_apply_sparse_checkout || !o->update)
1294                o->skip_sparse_checkout = 1;
1295        if (!o->skip_sparse_checkout) {
1296                char *sparse = git_pathdup("info/sparse-checkout");
1297                if (add_excludes_from_file_to_list(sparse, "", 0, &el, NULL) < 0)
1298                        o->skip_sparse_checkout = 1;
1299                else
1300                        o->el = &el;
1301                free(sparse);
1302        }
1303
1304        memset(&o->result, 0, sizeof(o->result));
1305        o->result.initialized = 1;
1306        o->result.timestamp.sec = o->src_index->timestamp.sec;
1307        o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1308        o->result.version = o->src_index->version;
1309        if (!o->src_index->split_index) {
1310                o->result.split_index = NULL;
1311        } else if (o->src_index == o->dst_index) {
1312                /*
1313                 * o->dst_index (and thus o->src_index) will be discarded
1314                 * and overwritten with o->result at the end of this function,
1315                 * so just use src_index's split_index to avoid having to
1316                 * create a new one.
1317                 */
1318                o->result.split_index = o->src_index->split_index;
1319                o->result.split_index->refcount++;
1320        } else {
1321                o->result.split_index = init_split_index(&o->result);
1322        }
1323        oidcpy(&o->result.oid, &o->src_index->oid);
1324        o->merge_size = len;
1325        mark_all_ce_unused(o->src_index);
1326
1327        /*
1328         * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1329         */
1330        if (!o->skip_sparse_checkout)
1331                mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1332
1333        if (!dfc)
1334                dfc = xcalloc(1, cache_entry_size(0));
1335        o->df_conflict_entry = dfc;
1336
1337        if (len) {
1338                const char *prefix = o->prefix ? o->prefix : "";
1339                struct traverse_info info;
1340
1341                setup_traverse_info(&info, prefix);
1342                info.fn = unpack_callback;
1343                info.data = o;
1344                info.show_all_errors = o->show_all_errors;
1345                info.pathspec = o->pathspec;
1346
1347                if (o->prefix) {
1348                        /*
1349                         * Unpack existing index entries that sort before the
1350                         * prefix the tree is spliced into.  Note that o->merge
1351                         * is always true in this case.
1352                         */
1353                        while (1) {
1354                                struct cache_entry *ce = next_cache_entry(o);
1355                                if (!ce)
1356                                        break;
1357                                if (ce_in_traverse_path(ce, &info))
1358                                        break;
1359                                if (unpack_index_entry(ce, o) < 0)
1360                                        goto return_failed;
1361                        }
1362                }
1363
1364                if (traverse_trees(len, t, &info) < 0)
1365                        goto return_failed;
1366        }
1367
1368        /* Any left-over entries in the index? */
1369        if (o->merge) {
1370                while (1) {
1371                        struct cache_entry *ce = next_cache_entry(o);
1372                        if (!ce)
1373                                break;
1374                        if (unpack_index_entry(ce, o) < 0)
1375                                goto return_failed;
1376                }
1377        }
1378        mark_all_ce_unused(o->src_index);
1379
1380        if (o->trivial_merges_only && o->nontrivial_merge) {
1381                ret = unpack_failed(o, "Merge requires file-level merging");
1382                goto done;
1383        }
1384
1385        if (!o->skip_sparse_checkout) {
1386                int empty_worktree = 1;
1387
1388                /*
1389                 * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1390                 * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1391                 * so apply_sparse_checkout() won't attempt to remove it from worktree
1392                 */
1393                mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1394
1395                ret = 0;
1396                for (i = 0; i < o->result.cache_nr; i++) {
1397                        struct cache_entry *ce = o->result.cache[i];
1398
1399                        /*
1400                         * Entries marked with CE_ADDED in merged_entry() do not have
1401                         * verify_absent() check (the check is effectively disabled
1402                         * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1403                         *
1404                         * Do the real check now because we have had
1405                         * correct CE_NEW_SKIP_WORKTREE
1406                         */
1407                        if (ce->ce_flags & CE_ADDED &&
1408                            verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1409                                if (!o->show_all_errors)
1410                                        goto return_failed;
1411                                ret = -1;
1412                        }
1413
1414                        if (apply_sparse_checkout(&o->result, ce, o)) {
1415                                if (!o->show_all_errors)
1416                                        goto return_failed;
1417                                ret = -1;
1418                        }
1419                        if (!ce_skip_worktree(ce))
1420                                empty_worktree = 0;
1421
1422                }
1423                if (ret < 0)
1424                        goto return_failed;
1425                /*
1426                 * Sparse checkout is meant to narrow down checkout area
1427                 * but it does not make sense to narrow down to empty working
1428                 * tree. This is usually a mistake in sparse checkout rules.
1429                 * Do not allow users to do that.
1430                 */
1431                if (o->result.cache_nr && empty_worktree) {
1432                        ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1433                        goto done;
1434                }
1435        }
1436
1437        ret = check_updates(o) ? (-2) : 0;
1438        if (o->dst_index) {
1439                if (!ret) {
1440                        if (!o->result.cache_tree)
1441                                o->result.cache_tree = cache_tree();
1442                        if (!cache_tree_fully_valid(o->result.cache_tree))
1443                                cache_tree_update(&o->result,
1444                                                  WRITE_TREE_SILENT |
1445                                                  WRITE_TREE_REPAIR);
1446                }
1447                move_index_extensions(&o->result, o->src_index);
1448                discard_index(o->dst_index);
1449                *o->dst_index = o->result;
1450        } else {
1451                discard_index(&o->result);
1452        }
1453        o->src_index = NULL;
1454
1455done:
1456        clear_exclude_list(&el);
1457        return ret;
1458
1459return_failed:
1460        if (o->show_all_errors)
1461                display_error_msgs(o);
1462        mark_all_ce_unused(o->src_index);
1463        ret = unpack_failed(o, NULL);
1464        if (o->exiting_early)
1465                ret = 0;
1466        goto done;
1467}
1468
1469/* Here come the merge functions */
1470
1471static int reject_merge(const struct cache_entry *ce,
1472                        struct unpack_trees_options *o)
1473{
1474        return o->gently ? -1 :
1475                add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1476}
1477
1478static int same(const struct cache_entry *a, const struct cache_entry *b)
1479{
1480        if (!!a != !!b)
1481                return 0;
1482        if (!a && !b)
1483                return 1;
1484        if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1485                return 0;
1486        return a->ce_mode == b->ce_mode &&
1487               !oidcmp(&a->oid, &b->oid);
1488}
1489
1490
1491/*
1492 * When a CE gets turned into an unmerged entry, we
1493 * want it to be up-to-date
1494 */
1495static int verify_uptodate_1(const struct cache_entry *ce,
1496                             struct unpack_trees_options *o,
1497                             enum unpack_trees_error_types error_type)
1498{
1499        struct stat st;
1500
1501        if (o->index_only)
1502                return 0;
1503
1504        /*
1505         * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1506         * if this entry is truly up-to-date because this file may be
1507         * overwritten.
1508         */
1509        if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1510                ; /* keep checking */
1511        else if (o->reset || ce_uptodate(ce))
1512                return 0;
1513
1514        if (!lstat(ce->name, &st)) {
1515                int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1516                unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1517
1518                if (submodule_from_ce(ce)) {
1519                        int r = check_submodule_move_head(ce,
1520                                "HEAD", oid_to_hex(&ce->oid), o);
1521                        if (r)
1522                                return o->gently ? -1 :
1523                                        add_rejected_path(o, error_type, ce->name);
1524                        return 0;
1525                }
1526
1527                if (!changed)
1528                        return 0;
1529                /*
1530                 * Historic default policy was to allow submodule to be out
1531                 * of sync wrt the superproject index. If the submodule was
1532                 * not considered interesting above, we don't care here.
1533                 */
1534                if (S_ISGITLINK(ce->ce_mode))
1535                        return 0;
1536
1537                errno = 0;
1538        }
1539        if (errno == ENOENT)
1540                return 0;
1541        return o->gently ? -1 :
1542                add_rejected_path(o, error_type, ce->name);
1543}
1544
1545int verify_uptodate(const struct cache_entry *ce,
1546                    struct unpack_trees_options *o)
1547{
1548        if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1549                return 0;
1550        return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1551}
1552
1553static int verify_uptodate_sparse(const struct cache_entry *ce,
1554                                  struct unpack_trees_options *o)
1555{
1556        return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1557}
1558
1559/*
1560 * TODO: We should actually invalidate o->result, not src_index [1].
1561 * But since cache tree and untracked cache both are not copied to
1562 * o->result until unpacking is complete, we invalidate them on
1563 * src_index instead with the assumption that they will be copied to
1564 * dst_index at the end.
1565 *
1566 * [1] src_index->cache_tree is also used in unpack_callback() so if
1567 * we invalidate o->result, we need to update it to use
1568 * o->result.cache_tree as well.
1569 */
1570static void invalidate_ce_path(const struct cache_entry *ce,
1571                               struct unpack_trees_options *o)
1572{
1573        if (!ce)
1574                return;
1575        cache_tree_invalidate_path(o->src_index, ce->name);
1576        untracked_cache_invalidate_path(o->src_index, ce->name, 1);
1577}
1578
1579/*
1580 * Check that checking out ce->sha1 in subdir ce->name is not
1581 * going to overwrite any working files.
1582 *
1583 * Currently, git does not checkout subprojects during a superproject
1584 * checkout, so it is not going to overwrite anything.
1585 */
1586static int verify_clean_submodule(const char *old_sha1,
1587                                  const struct cache_entry *ce,
1588                                  enum unpack_trees_error_types error_type,
1589                                  struct unpack_trees_options *o)
1590{
1591        if (!submodule_from_ce(ce))
1592                return 0;
1593
1594        return check_submodule_move_head(ce, old_sha1,
1595                                         oid_to_hex(&ce->oid), o);
1596}
1597
1598static int verify_clean_subdirectory(const struct cache_entry *ce,
1599                                     enum unpack_trees_error_types error_type,
1600                                     struct unpack_trees_options *o)
1601{
1602        /*
1603         * we are about to extract "ce->name"; we would not want to lose
1604         * anything in the existing directory there.
1605         */
1606        int namelen;
1607        int i;
1608        struct dir_struct d;
1609        char *pathbuf;
1610        int cnt = 0;
1611
1612        if (S_ISGITLINK(ce->ce_mode)) {
1613                struct object_id oid;
1614                int sub_head = resolve_gitlink_ref(ce->name, "HEAD", &oid);
1615                /*
1616                 * If we are not going to update the submodule, then
1617                 * we don't care.
1618                 */
1619                if (!sub_head && !oidcmp(&oid, &ce->oid))
1620                        return 0;
1621                return verify_clean_submodule(sub_head ? NULL : oid_to_hex(&oid),
1622                                              ce, error_type, o);
1623        }
1624
1625        /*
1626         * First let's make sure we do not have a local modification
1627         * in that directory.
1628         */
1629        namelen = ce_namelen(ce);
1630        for (i = locate_in_src_index(ce, o);
1631             i < o->src_index->cache_nr;
1632             i++) {
1633                struct cache_entry *ce2 = o->src_index->cache[i];
1634                int len = ce_namelen(ce2);
1635                if (len < namelen ||
1636                    strncmp(ce->name, ce2->name, namelen) ||
1637                    ce2->name[namelen] != '/')
1638                        break;
1639                /*
1640                 * ce2->name is an entry in the subdirectory to be
1641                 * removed.
1642                 */
1643                if (!ce_stage(ce2)) {
1644                        if (verify_uptodate(ce2, o))
1645                                return -1;
1646                        add_entry(o, ce2, CE_REMOVE, 0);
1647                        mark_ce_used(ce2, o);
1648                }
1649                cnt++;
1650        }
1651
1652        /*
1653         * Then we need to make sure that we do not lose a locally
1654         * present file that is not ignored.
1655         */
1656        pathbuf = xstrfmt("%.*s/", namelen, ce->name);
1657
1658        memset(&d, 0, sizeof(d));
1659        if (o->dir)
1660                d.exclude_per_dir = o->dir->exclude_per_dir;
1661        i = read_directory(&d, o->src_index, pathbuf, namelen+1, NULL);
1662        if (i)
1663                return o->gently ? -1 :
1664                        add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1665        free(pathbuf);
1666        return cnt;
1667}
1668
1669/*
1670 * This gets called when there was no index entry for the tree entry 'dst',
1671 * but we found a file in the working tree that 'lstat()' said was fine,
1672 * and we're on a case-insensitive filesystem.
1673 *
1674 * See if we can find a case-insensitive match in the index that also
1675 * matches the stat information, and assume it's that other file!
1676 */
1677static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1678{
1679        const struct cache_entry *src;
1680
1681        src = index_file_exists(o->src_index, name, len, 1);
1682        return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1683}
1684
1685static int check_ok_to_remove(const char *name, int len, int dtype,
1686                              const struct cache_entry *ce, struct stat *st,
1687                              enum unpack_trees_error_types error_type,
1688                              struct unpack_trees_options *o)
1689{
1690        const struct cache_entry *result;
1691
1692        /*
1693         * It may be that the 'lstat()' succeeded even though
1694         * target 'ce' was absent, because there is an old
1695         * entry that is different only in case..
1696         *
1697         * Ignore that lstat() if it matches.
1698         */
1699        if (ignore_case && icase_exists(o, name, len, st))
1700                return 0;
1701
1702        if (o->dir &&
1703            is_excluded(o->dir, o->src_index, name, &dtype))
1704                /*
1705                 * ce->name is explicitly excluded, so it is Ok to
1706                 * overwrite it.
1707                 */
1708                return 0;
1709        if (S_ISDIR(st->st_mode)) {
1710                /*
1711                 * We are checking out path "foo" and
1712                 * found "foo/." in the working tree.
1713                 * This is tricky -- if we have modified
1714                 * files that are in "foo/" we would lose
1715                 * them.
1716                 */
1717                if (verify_clean_subdirectory(ce, error_type, o) < 0)
1718                        return -1;
1719                return 0;
1720        }
1721
1722        /*
1723         * The previous round may already have decided to
1724         * delete this path, which is in a subdirectory that
1725         * is being replaced with a blob.
1726         */
1727        result = index_file_exists(&o->result, name, len, 0);
1728        if (result) {
1729                if (result->ce_flags & CE_REMOVE)
1730                        return 0;
1731        }
1732
1733        return o->gently ? -1 :
1734                add_rejected_path(o, error_type, name);
1735}
1736
1737/*
1738 * We do not want to remove or overwrite a working tree file that
1739 * is not tracked, unless it is ignored.
1740 */
1741static int verify_absent_1(const struct cache_entry *ce,
1742                           enum unpack_trees_error_types error_type,
1743                           struct unpack_trees_options *o)
1744{
1745        int len;
1746        struct stat st;
1747
1748        if (o->index_only || o->reset || !o->update)
1749                return 0;
1750
1751        len = check_leading_path(ce->name, ce_namelen(ce));
1752        if (!len)
1753                return 0;
1754        else if (len > 0) {
1755                char *path;
1756                int ret;
1757
1758                path = xmemdupz(ce->name, len);
1759                if (lstat(path, &st))
1760                        ret = error_errno("cannot stat '%s'", path);
1761                else {
1762                        if (submodule_from_ce(ce))
1763                                ret = check_submodule_move_head(ce,
1764                                                                oid_to_hex(&ce->oid),
1765                                                                NULL, o);
1766                        else
1767                                ret = check_ok_to_remove(path, len, DT_UNKNOWN, NULL,
1768                                                         &st, error_type, o);
1769                }
1770                free(path);
1771                return ret;
1772        } else if (lstat(ce->name, &st)) {
1773                if (errno != ENOENT)
1774                        return error_errno("cannot stat '%s'", ce->name);
1775                return 0;
1776        } else {
1777                if (submodule_from_ce(ce))
1778                        return check_submodule_move_head(ce, oid_to_hex(&ce->oid),
1779                                                         NULL, o);
1780
1781                return check_ok_to_remove(ce->name, ce_namelen(ce),
1782                                          ce_to_dtype(ce), ce, &st,
1783                                          error_type, o);
1784        }
1785}
1786
1787static int verify_absent(const struct cache_entry *ce,
1788                         enum unpack_trees_error_types error_type,
1789                         struct unpack_trees_options *o)
1790{
1791        if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1792                return 0;
1793        return verify_absent_1(ce, error_type, o);
1794}
1795
1796static int verify_absent_sparse(const struct cache_entry *ce,
1797                                enum unpack_trees_error_types error_type,
1798                                struct unpack_trees_options *o)
1799{
1800        enum unpack_trees_error_types orphaned_error = error_type;
1801        if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1802                orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1803
1804        return verify_absent_1(ce, orphaned_error, o);
1805}
1806
1807static int merged_entry(const struct cache_entry *ce,
1808                        const struct cache_entry *old,
1809                        struct unpack_trees_options *o)
1810{
1811        int update = CE_UPDATE;
1812        struct cache_entry *merge = dup_cache_entry(ce, &o->result);
1813
1814        if (!old) {
1815                /*
1816                 * New index entries. In sparse checkout, the following
1817                 * verify_absent() will be delayed until after
1818                 * traverse_trees() finishes in unpack_trees(), then:
1819                 *
1820                 *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1821                 *  - verify_absent() be called again, this time with
1822                 *    correct CE_NEW_SKIP_WORKTREE
1823                 *
1824                 * verify_absent() call here does nothing in sparse
1825                 * checkout (i.e. o->skip_sparse_checkout == 0)
1826                 */
1827                update |= CE_ADDED;
1828                merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1829
1830                if (verify_absent(merge,
1831                                  ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1832                        discard_cache_entry(merge);
1833                        return -1;
1834                }
1835                invalidate_ce_path(merge, o);
1836
1837                if (submodule_from_ce(ce)) {
1838                        int ret = check_submodule_move_head(ce, NULL,
1839                                                            oid_to_hex(&ce->oid),
1840                                                            o);
1841                        if (ret)
1842                                return ret;
1843                }
1844
1845        } else if (!(old->ce_flags & CE_CONFLICTED)) {
1846                /*
1847                 * See if we can re-use the old CE directly?
1848                 * That way we get the uptodate stat info.
1849                 *
1850                 * This also removes the UPDATE flag on a match; otherwise
1851                 * we will end up overwriting local changes in the work tree.
1852                 */
1853                if (same(old, merge)) {
1854                        copy_cache_entry(merge, old);
1855                        update = 0;
1856                } else {
1857                        if (verify_uptodate(old, o)) {
1858                                discard_cache_entry(merge);
1859                                return -1;
1860                        }
1861                        /* Migrate old flags over */
1862                        update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1863                        invalidate_ce_path(old, o);
1864                }
1865
1866                if (submodule_from_ce(ce)) {
1867                        int ret = check_submodule_move_head(ce, oid_to_hex(&old->oid),
1868                                                            oid_to_hex(&ce->oid),
1869                                                            o);
1870                        if (ret)
1871                                return ret;
1872                }
1873        } else {
1874                /*
1875                 * Previously unmerged entry left as an existence
1876                 * marker by read_index_unmerged();
1877                 */
1878                invalidate_ce_path(old, o);
1879        }
1880
1881        do_add_entry(o, merge, update, CE_STAGEMASK);
1882        return 1;
1883}
1884
1885static int deleted_entry(const struct cache_entry *ce,
1886                         const struct cache_entry *old,
1887                         struct unpack_trees_options *o)
1888{
1889        /* Did it exist in the index? */
1890        if (!old) {
1891                if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1892                        return -1;
1893                return 0;
1894        }
1895        if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1896                return -1;
1897        add_entry(o, ce, CE_REMOVE, 0);
1898        invalidate_ce_path(ce, o);
1899        return 1;
1900}
1901
1902static int keep_entry(const struct cache_entry *ce,
1903                      struct unpack_trees_options *o)
1904{
1905        add_entry(o, ce, 0, 0);
1906        return 1;
1907}
1908
1909#if DBRT_DEBUG
1910static void show_stage_entry(FILE *o,
1911                             const char *label, const struct cache_entry *ce)
1912{
1913        if (!ce)
1914                fprintf(o, "%s (missing)\n", label);
1915        else
1916                fprintf(o, "%s%06o %s %d\t%s\n",
1917                        label,
1918                        ce->ce_mode,
1919                        oid_to_hex(&ce->oid),
1920                        ce_stage(ce),
1921                        ce->name);
1922}
1923#endif
1924
1925int threeway_merge(const struct cache_entry * const *stages,
1926                   struct unpack_trees_options *o)
1927{
1928        const struct cache_entry *index;
1929        const struct cache_entry *head;
1930        const struct cache_entry *remote = stages[o->head_idx + 1];
1931        int count;
1932        int head_match = 0;
1933        int remote_match = 0;
1934
1935        int df_conflict_head = 0;
1936        int df_conflict_remote = 0;
1937
1938        int any_anc_missing = 0;
1939        int no_anc_exists = 1;
1940        int i;
1941
1942        for (i = 1; i < o->head_idx; i++) {
1943                if (!stages[i] || stages[i] == o->df_conflict_entry)
1944                        any_anc_missing = 1;
1945                else
1946                        no_anc_exists = 0;
1947        }
1948
1949        index = stages[0];
1950        head = stages[o->head_idx];
1951
1952        if (head == o->df_conflict_entry) {
1953                df_conflict_head = 1;
1954                head = NULL;
1955        }
1956
1957        if (remote == o->df_conflict_entry) {
1958                df_conflict_remote = 1;
1959                remote = NULL;
1960        }
1961
1962        /*
1963         * First, if there's a #16 situation, note that to prevent #13
1964         * and #14.
1965         */
1966        if (!same(remote, head)) {
1967                for (i = 1; i < o->head_idx; i++) {
1968                        if (same(stages[i], head)) {
1969                                head_match = i;
1970                        }
1971                        if (same(stages[i], remote)) {
1972                                remote_match = i;
1973                        }
1974                }
1975        }
1976
1977        /*
1978         * We start with cases where the index is allowed to match
1979         * something other than the head: #14(ALT) and #2ALT, where it
1980         * is permitted to match the result instead.
1981         */
1982        /* #14, #14ALT, #2ALT */
1983        if (remote && !df_conflict_head && head_match && !remote_match) {
1984                if (index && !same(index, remote) && !same(index, head))
1985                        return reject_merge(index, o);
1986                return merged_entry(remote, index, o);
1987        }
1988        /*
1989         * If we have an entry in the index cache, then we want to
1990         * make sure that it matches head.
1991         */
1992        if (index && !same(index, head))
1993                return reject_merge(index, o);
1994
1995        if (head) {
1996                /* #5ALT, #15 */
1997                if (same(head, remote))
1998                        return merged_entry(head, index, o);
1999                /* #13, #3ALT */
2000                if (!df_conflict_remote && remote_match && !head_match)
2001                        return merged_entry(head, index, o);
2002        }
2003
2004        /* #1 */
2005        if (!head && !remote && any_anc_missing)
2006                return 0;
2007
2008        /*
2009         * Under the "aggressive" rule, we resolve mostly trivial
2010         * cases that we historically had git-merge-one-file resolve.
2011         */
2012        if (o->aggressive) {
2013                int head_deleted = !head;
2014                int remote_deleted = !remote;
2015                const struct cache_entry *ce = NULL;
2016
2017                if (index)
2018                        ce = index;
2019                else if (head)
2020                        ce = head;
2021                else if (remote)
2022                        ce = remote;
2023                else {
2024                        for (i = 1; i < o->head_idx; i++) {
2025                                if (stages[i] && stages[i] != o->df_conflict_entry) {
2026                                        ce = stages[i];
2027                                        break;
2028                                }
2029                        }
2030                }
2031
2032                /*
2033                 * Deleted in both.
2034                 * Deleted in one and unchanged in the other.
2035                 */
2036                if ((head_deleted && remote_deleted) ||
2037                    (head_deleted && remote && remote_match) ||
2038                    (remote_deleted && head && head_match)) {
2039                        if (index)
2040                                return deleted_entry(index, index, o);
2041                        if (ce && !head_deleted) {
2042                                if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
2043                                        return -1;
2044                        }
2045                        return 0;
2046                }
2047                /*
2048                 * Added in both, identically.
2049                 */
2050                if (no_anc_exists && head && remote && same(head, remote))
2051                        return merged_entry(head, index, o);
2052
2053        }
2054
2055        /* Below are "no merge" cases, which require that the index be
2056         * up-to-date to avoid the files getting overwritten with
2057         * conflict resolution files.
2058         */
2059        if (index) {
2060                if (verify_uptodate(index, o))
2061                        return -1;
2062        }
2063
2064        o->nontrivial_merge = 1;
2065
2066        /* #2, #3, #4, #6, #7, #9, #10, #11. */
2067        count = 0;
2068        if (!head_match || !remote_match) {
2069                for (i = 1; i < o->head_idx; i++) {
2070                        if (stages[i] && stages[i] != o->df_conflict_entry) {
2071                                keep_entry(stages[i], o);
2072                                count++;
2073                                break;
2074                        }
2075                }
2076        }
2077#if DBRT_DEBUG
2078        else {
2079                fprintf(stderr, "read-tree: warning #16 detected\n");
2080                show_stage_entry(stderr, "head   ", stages[head_match]);
2081                show_stage_entry(stderr, "remote ", stages[remote_match]);
2082        }
2083#endif
2084        if (head) { count += keep_entry(head, o); }
2085        if (remote) { count += keep_entry(remote, o); }
2086        return count;
2087}
2088
2089/*
2090 * Two-way merge.
2091 *
2092 * The rule is to "carry forward" what is in the index without losing
2093 * information across a "fast-forward", favoring a successful merge
2094 * over a merge failure when it makes sense.  For details of the
2095 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
2096 *
2097 */
2098int twoway_merge(const struct cache_entry * const *src,
2099                 struct unpack_trees_options *o)
2100{
2101        const struct cache_entry *current = src[0];
2102        const struct cache_entry *oldtree = src[1];
2103        const struct cache_entry *newtree = src[2];
2104
2105        if (o->merge_size != 2)
2106                return error("Cannot do a twoway merge of %d trees",
2107                             o->merge_size);
2108
2109        if (oldtree == o->df_conflict_entry)
2110                oldtree = NULL;
2111        if (newtree == o->df_conflict_entry)
2112                newtree = NULL;
2113
2114        if (current) {
2115                if (current->ce_flags & CE_CONFLICTED) {
2116                        if (same(oldtree, newtree) || o->reset) {
2117                                if (!newtree)
2118                                        return deleted_entry(current, current, o);
2119                                else
2120                                        return merged_entry(newtree, current, o);
2121                        }
2122                        return reject_merge(current, o);
2123                } else if ((!oldtree && !newtree) || /* 4 and 5 */
2124                         (!oldtree && newtree &&
2125                          same(current, newtree)) || /* 6 and 7 */
2126                         (oldtree && newtree &&
2127                          same(oldtree, newtree)) || /* 14 and 15 */
2128                         (oldtree && newtree &&
2129                          !same(oldtree, newtree) && /* 18 and 19 */
2130                          same(current, newtree))) {
2131                        return keep_entry(current, o);
2132                } else if (oldtree && !newtree && same(current, oldtree)) {
2133                        /* 10 or 11 */
2134                        return deleted_entry(oldtree, current, o);
2135                } else if (oldtree && newtree &&
2136                         same(current, oldtree) && !same(current, newtree)) {
2137                        /* 20 or 21 */
2138                        return merged_entry(newtree, current, o);
2139                } else
2140                        return reject_merge(current, o);
2141        }
2142        else if (newtree) {
2143                if (oldtree && !o->initial_checkout) {
2144                        /*
2145                         * deletion of the path was staged;
2146                         */
2147                        if (same(oldtree, newtree))
2148                                return 1;
2149                        return reject_merge(oldtree, o);
2150                }
2151                return merged_entry(newtree, current, o);
2152        }
2153        return deleted_entry(oldtree, current, o);
2154}
2155
2156/*
2157 * Bind merge.
2158 *
2159 * Keep the index entries at stage0, collapse stage1 but make sure
2160 * stage0 does not have anything there.
2161 */
2162int bind_merge(const struct cache_entry * const *src,
2163               struct unpack_trees_options *o)
2164{
2165        const struct cache_entry *old = src[0];
2166        const struct cache_entry *a = src[1];
2167
2168        if (o->merge_size != 1)
2169                return error("Cannot do a bind merge of %d trees",
2170                             o->merge_size);
2171        if (a && old)
2172                return o->gently ? -1 :
2173                        error(ERRORMSG(o, ERROR_BIND_OVERLAP),
2174                              super_prefixed(a->name),
2175                              super_prefixed(old->name));
2176        if (!a)
2177                return keep_entry(old, o);
2178        else
2179                return merged_entry(a, NULL, o);
2180}
2181
2182/*
2183 * One-way merge.
2184 *
2185 * The rule is:
2186 * - take the stat information from stage0, take the data from stage1
2187 */
2188int oneway_merge(const struct cache_entry * const *src,
2189                 struct unpack_trees_options *o)
2190{
2191        const struct cache_entry *old = src[0];
2192        const struct cache_entry *a = src[1];
2193
2194        if (o->merge_size != 1)
2195                return error("Cannot do a oneway merge of %d trees",
2196                             o->merge_size);
2197
2198        if (!a || a == o->df_conflict_entry)
2199                return deleted_entry(old, old, o);
2200
2201        if (old && same(old, a)) {
2202                int update = 0;
2203                if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
2204                        struct stat st;
2205                        if (lstat(old->name, &st) ||
2206                            ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
2207                                update |= CE_UPDATE;
2208                }
2209                if (o->update && S_ISGITLINK(old->ce_mode) &&
2210                    should_update_submodules() && !verify_uptodate(old, o))
2211                        update |= CE_UPDATE;
2212                add_entry(o, old, update, 0);
2213                return 0;
2214        }
2215        return merged_entry(a, old, o);
2216}