unpack-trees.con commit Merge branch 'js/msgfmt-on-windows' of ../git-gui into js/git-gui-msgfmt-on-windows (90dbf22)
   1#define NO_THE_INDEX_COMPATIBILITY_MACROS
   2#include "cache.h"
   3#include "config.h"
   4#include "dir.h"
   5#include "tree.h"
   6#include "tree-walk.h"
   7#include "cache-tree.h"
   8#include "unpack-trees.h"
   9#include "progress.h"
  10#include "refs.h"
  11#include "attr.h"
  12#include "split-index.h"
  13#include "dir.h"
  14#include "submodule.h"
  15#include "submodule-config.h"
  16
  17/*
  18 * Error messages expected by scripts out of plumbing commands such as
  19 * read-tree.  Non-scripted Porcelain is not required to use these messages
  20 * and in fact are encouraged to reword them to better suit their particular
  21 * situation better.  See how "git checkout" and "git merge" replaces
  22 * them using setup_unpack_trees_porcelain(), for example.
  23 */
  24static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
  25        /* ERROR_WOULD_OVERWRITE */
  26        "Entry '%s' would be overwritten by merge. Cannot merge.",
  27
  28        /* ERROR_NOT_UPTODATE_FILE */
  29        "Entry '%s' not uptodate. Cannot merge.",
  30
  31        /* ERROR_NOT_UPTODATE_DIR */
  32        "Updating '%s' would lose untracked files in it",
  33
  34        /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
  35        "Untracked working tree file '%s' would be overwritten by merge.",
  36
  37        /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
  38        "Untracked working tree file '%s' would be removed by merge.",
  39
  40        /* ERROR_BIND_OVERLAP */
  41        "Entry '%s' overlaps with '%s'.  Cannot bind.",
  42
  43        /* ERROR_SPARSE_NOT_UPTODATE_FILE */
  44        "Entry '%s' not uptodate. Cannot update sparse checkout.",
  45
  46        /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
  47        "Working tree file '%s' would be overwritten by sparse checkout update.",
  48
  49        /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
  50        "Working tree file '%s' would be removed by sparse checkout update.",
  51
  52        /* ERROR_WOULD_LOSE_SUBMODULE */
  53        "Submodule '%s' cannot checkout new HEAD.",
  54};
  55
  56#define ERRORMSG(o,type) \
  57        ( ((o) && (o)->msgs[(type)]) \
  58          ? ((o)->msgs[(type)])      \
  59          : (unpack_plumbing_errors[(type)]) )
  60
  61static const char *super_prefixed(const char *path)
  62{
  63        /*
  64         * It is necessary and sufficient to have two static buffers
  65         * here, as the return value of this function is fed to
  66         * error() using the unpack_*_errors[] templates we see above.
  67         */
  68        static struct strbuf buf[2] = {STRBUF_INIT, STRBUF_INIT};
  69        static int super_prefix_len = -1;
  70        static unsigned idx = ARRAY_SIZE(buf) - 1;
  71
  72        if (super_prefix_len < 0) {
  73                const char *super_prefix = get_super_prefix();
  74                if (!super_prefix) {
  75                        super_prefix_len = 0;
  76                } else {
  77                        int i;
  78                        for (i = 0; i < ARRAY_SIZE(buf); i++)
  79                                strbuf_addstr(&buf[i], super_prefix);
  80                        super_prefix_len = buf[0].len;
  81                }
  82        }
  83
  84        if (!super_prefix_len)
  85                return path;
  86
  87        if (++idx >= ARRAY_SIZE(buf))
  88                idx = 0;
  89
  90        strbuf_setlen(&buf[idx], super_prefix_len);
  91        strbuf_addstr(&buf[idx], path);
  92
  93        return buf[idx].buf;
  94}
  95
  96void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
  97                                  const char *cmd)
  98{
  99        int i;
 100        const char **msgs = opts->msgs;
 101        const char *msg;
 102
 103        if (!strcmp(cmd, "checkout"))
 104                msg = advice_commit_before_merge
 105                      ? _("Your local changes to the following files would be overwritten by checkout:\n%%s"
 106                          "Please commit your changes or stash them before you switch branches.")
 107                      : _("Your local changes to the following files would be overwritten by checkout:\n%%s");
 108        else if (!strcmp(cmd, "merge"))
 109                msg = advice_commit_before_merge
 110                      ? _("Your local changes to the following files would be overwritten by merge:\n%%s"
 111                          "Please commit your changes or stash them before you merge.")
 112                      : _("Your local changes to the following files would be overwritten by merge:\n%%s");
 113        else
 114                msg = advice_commit_before_merge
 115                      ? _("Your local changes to the following files would be overwritten by %s:\n%%s"
 116                          "Please commit your changes or stash them before you %s.")
 117                      : _("Your local changes to the following files would be overwritten by %s:\n%%s");
 118        msgs[ERROR_WOULD_OVERWRITE] = msgs[ERROR_NOT_UPTODATE_FILE] =
 119                xstrfmt(msg, cmd, cmd);
 120
 121        msgs[ERROR_NOT_UPTODATE_DIR] =
 122                _("Updating the following directories would lose untracked files in them:\n%s");
 123
 124        if (!strcmp(cmd, "checkout"))
 125                msg = advice_commit_before_merge
 126                      ? _("The following untracked working tree files would be removed by checkout:\n%%s"
 127                          "Please move or remove them before you switch branches.")
 128                      : _("The following untracked working tree files would be removed by checkout:\n%%s");
 129        else if (!strcmp(cmd, "merge"))
 130                msg = advice_commit_before_merge
 131                      ? _("The following untracked working tree files would be removed by merge:\n%%s"
 132                          "Please move or remove them before you merge.")
 133                      : _("The following untracked working tree files would be removed by merge:\n%%s");
 134        else
 135                msg = advice_commit_before_merge
 136                      ? _("The following untracked working tree files would be removed by %s:\n%%s"
 137                          "Please move or remove them before you %s.")
 138                      : _("The following untracked working tree files would be removed by %s:\n%%s");
 139        msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] = xstrfmt(msg, cmd, cmd);
 140
 141        if (!strcmp(cmd, "checkout"))
 142                msg = advice_commit_before_merge
 143                      ? _("The following untracked working tree files would be overwritten by checkout:\n%%s"
 144                          "Please move or remove them before you switch branches.")
 145                      : _("The following untracked working tree files would be overwritten by checkout:\n%%s");
 146        else if (!strcmp(cmd, "merge"))
 147                msg = advice_commit_before_merge
 148                      ? _("The following untracked working tree files would be overwritten by merge:\n%%s"
 149                          "Please move or remove them before you merge.")
 150                      : _("The following untracked working tree files would be overwritten by merge:\n%%s");
 151        else
 152                msg = advice_commit_before_merge
 153                      ? _("The following untracked working tree files would be overwritten by %s:\n%%s"
 154                          "Please move or remove them before you %s.")
 155                      : _("The following untracked working tree files would be overwritten by %s:\n%%s");
 156        msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] = xstrfmt(msg, cmd, cmd);
 157
 158        /*
 159         * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
 160         * cannot easily display it as a list.
 161         */
 162        msgs[ERROR_BIND_OVERLAP] = _("Entry '%s' overlaps with '%s'.  Cannot bind.");
 163
 164        msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
 165                _("Cannot update sparse checkout: the following entries are not up-to-date:\n%s");
 166        msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
 167                _("The following working tree files would be overwritten by sparse checkout update:\n%s");
 168        msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
 169                _("The following working tree files would be removed by sparse checkout update:\n%s");
 170        msgs[ERROR_WOULD_LOSE_SUBMODULE] =
 171                _("Cannot update submodule:\n%s");
 172
 173        opts->show_all_errors = 1;
 174        /* rejected paths may not have a static buffer */
 175        for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
 176                opts->unpack_rejects[i].strdup_strings = 1;
 177}
 178
 179static int do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
 180                         unsigned int set, unsigned int clear)
 181{
 182        clear |= CE_HASHED;
 183
 184        if (set & CE_REMOVE)
 185                set |= CE_WT_REMOVE;
 186
 187        ce->ce_flags = (ce->ce_flags & ~clear) | set;
 188        return add_index_entry(&o->result, ce,
 189                               ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 190}
 191
 192static struct cache_entry *dup_entry(const struct cache_entry *ce)
 193{
 194        unsigned int size = ce_size(ce);
 195        struct cache_entry *new = xmalloc(size);
 196
 197        memcpy(new, ce, size);
 198        return new;
 199}
 200
 201static void add_entry(struct unpack_trees_options *o,
 202                      const struct cache_entry *ce,
 203                      unsigned int set, unsigned int clear)
 204{
 205        do_add_entry(o, dup_entry(ce), set, clear);
 206}
 207
 208/*
 209 * add error messages on path <path>
 210 * corresponding to the type <e> with the message <msg>
 211 * indicating if it should be display in porcelain or not
 212 */
 213static int add_rejected_path(struct unpack_trees_options *o,
 214                             enum unpack_trees_error_types e,
 215                             const char *path)
 216{
 217        if (!o->show_all_errors)
 218                return error(ERRORMSG(o, e), super_prefixed(path));
 219
 220        /*
 221         * Otherwise, insert in a list for future display by
 222         * display_error_msgs()
 223         */
 224        string_list_append(&o->unpack_rejects[e], path);
 225        return -1;
 226}
 227
 228/*
 229 * display all the error messages stored in a nice way
 230 */
 231static void display_error_msgs(struct unpack_trees_options *o)
 232{
 233        int e, i;
 234        int something_displayed = 0;
 235        for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
 236                struct string_list *rejects = &o->unpack_rejects[e];
 237                if (rejects->nr > 0) {
 238                        struct strbuf path = STRBUF_INIT;
 239                        something_displayed = 1;
 240                        for (i = 0; i < rejects->nr; i++)
 241                                strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
 242                        error(ERRORMSG(o, e), super_prefixed(path.buf));
 243                        strbuf_release(&path);
 244                }
 245                string_list_clear(rejects, 0);
 246        }
 247        if (something_displayed)
 248                fprintf(stderr, _("Aborting\n"));
 249}
 250
 251static int check_submodule_move_head(const struct cache_entry *ce,
 252                                     const char *old_id,
 253                                     const char *new_id,
 254                                     struct unpack_trees_options *o)
 255{
 256        unsigned flags = SUBMODULE_MOVE_HEAD_DRY_RUN;
 257        const struct submodule *sub = submodule_from_ce(ce);
 258        if (!sub)
 259                return 0;
 260
 261        if (o->reset)
 262                flags |= SUBMODULE_MOVE_HEAD_FORCE;
 263
 264        switch (sub->update_strategy.type) {
 265        case SM_UPDATE_UNSPECIFIED:
 266        case SM_UPDATE_CHECKOUT:
 267                if (submodule_move_head(ce->name, old_id, new_id, flags))
 268                        return o->gently ? -1 :
 269                                add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
 270                return 0;
 271        case SM_UPDATE_NONE:
 272                return 0;
 273        case SM_UPDATE_REBASE:
 274        case SM_UPDATE_MERGE:
 275        case SM_UPDATE_COMMAND:
 276        default:
 277                warning(_("submodule update strategy not supported for submodule '%s'"), ce->name);
 278                return -1;
 279        }
 280}
 281
 282static void reload_gitmodules_file(struct index_state *index,
 283                                   struct checkout *state)
 284{
 285        int i;
 286        for (i = 0; i < index->cache_nr; i++) {
 287                struct cache_entry *ce = index->cache[i];
 288                if (ce->ce_flags & CE_UPDATE) {
 289                        int r = strcmp(ce->name, ".gitmodules");
 290                        if (r < 0)
 291                                continue;
 292                        else if (r == 0) {
 293                                submodule_free();
 294                                checkout_entry(ce, state, NULL);
 295                                gitmodules_config();
 296                                git_config(submodule_config, NULL);
 297                        } else
 298                                break;
 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                switch (sub->update_strategy.type) {
 312                case SM_UPDATE_UNSPECIFIED:
 313                case SM_UPDATE_CHECKOUT:
 314                case SM_UPDATE_REBASE:
 315                case SM_UPDATE_MERGE:
 316                        /* state.force is set at the caller. */
 317                        submodule_move_head(ce->name, "HEAD", NULL,
 318                                            SUBMODULE_MOVE_HEAD_FORCE);
 319                        break;
 320                case SM_UPDATE_NONE:
 321                case SM_UPDATE_COMMAND:
 322                        return; /* Do not touch the submodule. */
 323                }
 324        }
 325        if (!check_leading_path(ce->name, ce_namelen(ce)))
 326                return;
 327        if (remove_or_warn(ce->ce_mode, ce->name))
 328                return;
 329        schedule_dir_for_removal(ce->name, ce_namelen(ce));
 330}
 331
 332static struct progress *get_progress(struct unpack_trees_options *o)
 333{
 334        unsigned cnt = 0, total = 0;
 335        struct index_state *index = &o->result;
 336
 337        if (!o->update || !o->verbose_update)
 338                return NULL;
 339
 340        for (; cnt < index->cache_nr; cnt++) {
 341                const struct cache_entry *ce = index->cache[cnt];
 342                if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
 343                        total++;
 344        }
 345
 346        return start_progress_delay(_("Checking out files"),
 347                                    total, 50, 1);
 348}
 349
 350static int check_updates(struct unpack_trees_options *o)
 351{
 352        unsigned cnt = 0;
 353        int errs = 0;
 354        struct progress *progress = NULL;
 355        struct index_state *index = &o->result;
 356        struct checkout state = CHECKOUT_INIT;
 357        int i;
 358
 359        state.force = 1;
 360        state.quiet = 1;
 361        state.refresh_cache = 1;
 362        state.istate = index;
 363
 364        progress = get_progress(o);
 365
 366        if (o->update)
 367                git_attr_set_direction(GIT_ATTR_CHECKOUT, index);
 368        for (i = 0; i < index->cache_nr; i++) {
 369                const struct cache_entry *ce = index->cache[i];
 370
 371                if (ce->ce_flags & CE_WT_REMOVE) {
 372                        display_progress(progress, ++cnt);
 373                        if (o->update && !o->dry_run)
 374                                unlink_entry(ce);
 375                }
 376        }
 377        remove_marked_cache_entries(index);
 378        remove_scheduled_dirs();
 379
 380        if (should_update_submodules() && o->update && !o->dry_run)
 381                reload_gitmodules_file(index, &state);
 382
 383        for (i = 0; i < index->cache_nr; i++) {
 384                struct cache_entry *ce = index->cache[i];
 385
 386                if (ce->ce_flags & CE_UPDATE) {
 387                        if (ce->ce_flags & CE_WT_REMOVE)
 388                                die("BUG: both update and delete flags are set on %s",
 389                                    ce->name);
 390                        display_progress(progress, ++cnt);
 391                        ce->ce_flags &= ~CE_UPDATE;
 392                        if (o->update && !o->dry_run) {
 393                                errs |= checkout_entry(ce, &state, NULL);
 394                        }
 395                }
 396        }
 397        stop_progress(&progress);
 398        if (o->update)
 399                git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
 400        return errs != 0;
 401}
 402
 403static int verify_uptodate_sparse(const struct cache_entry *ce,
 404                                  struct unpack_trees_options *o);
 405static int verify_absent_sparse(const struct cache_entry *ce,
 406                                enum unpack_trees_error_types,
 407                                struct unpack_trees_options *o);
 408
 409static int apply_sparse_checkout(struct index_state *istate,
 410                                 struct cache_entry *ce,
 411                                 struct unpack_trees_options *o)
 412{
 413        int was_skip_worktree = ce_skip_worktree(ce);
 414
 415        if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
 416                ce->ce_flags |= CE_SKIP_WORKTREE;
 417        else
 418                ce->ce_flags &= ~CE_SKIP_WORKTREE;
 419        if (was_skip_worktree != ce_skip_worktree(ce)) {
 420                ce->ce_flags |= CE_UPDATE_IN_BASE;
 421                istate->cache_changed |= CE_ENTRY_CHANGED;
 422        }
 423
 424        /*
 425         * if (!was_skip_worktree && !ce_skip_worktree()) {
 426         *      This is perfectly normal. Move on;
 427         * }
 428         */
 429
 430        /*
 431         * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
 432         * area as a result of ce_skip_worktree() shortcuts in
 433         * verify_absent() and verify_uptodate().
 434         * Make sure they don't modify worktree if they are already
 435         * outside checkout area
 436         */
 437        if (was_skip_worktree && ce_skip_worktree(ce)) {
 438                ce->ce_flags &= ~CE_UPDATE;
 439
 440                /*
 441                 * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
 442                 * on to get that file removed from both index and worktree.
 443                 * If that file is already outside worktree area, don't
 444                 * bother remove it.
 445                 */
 446                if (ce->ce_flags & CE_REMOVE)
 447                        ce->ce_flags &= ~CE_WT_REMOVE;
 448        }
 449
 450        if (!was_skip_worktree && ce_skip_worktree(ce)) {
 451                /*
 452                 * If CE_UPDATE is set, verify_uptodate() must be called already
 453                 * also stat info may have lost after merged_entry() so calling
 454                 * verify_uptodate() again may fail
 455                 */
 456                if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
 457                        return -1;
 458                ce->ce_flags |= CE_WT_REMOVE;
 459                ce->ce_flags &= ~CE_UPDATE;
 460        }
 461        if (was_skip_worktree && !ce_skip_worktree(ce)) {
 462                if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
 463                        return -1;
 464                ce->ce_flags |= CE_UPDATE;
 465        }
 466        return 0;
 467}
 468
 469static inline int call_unpack_fn(const struct cache_entry * const *src,
 470                                 struct unpack_trees_options *o)
 471{
 472        int ret = o->fn(src, o);
 473        if (ret > 0)
 474                ret = 0;
 475        return ret;
 476}
 477
 478static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
 479{
 480        ce->ce_flags |= CE_UNPACKED;
 481
 482        if (o->cache_bottom < o->src_index->cache_nr &&
 483            o->src_index->cache[o->cache_bottom] == ce) {
 484                int bottom = o->cache_bottom;
 485                while (bottom < o->src_index->cache_nr &&
 486                       o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
 487                        bottom++;
 488                o->cache_bottom = bottom;
 489        }
 490}
 491
 492static void mark_all_ce_unused(struct index_state *index)
 493{
 494        int i;
 495        for (i = 0; i < index->cache_nr; i++)
 496                index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
 497}
 498
 499static int locate_in_src_index(const struct cache_entry *ce,
 500                               struct unpack_trees_options *o)
 501{
 502        struct index_state *index = o->src_index;
 503        int len = ce_namelen(ce);
 504        int pos = index_name_pos(index, ce->name, len);
 505        if (pos < 0)
 506                pos = -1 - pos;
 507        return pos;
 508}
 509
 510/*
 511 * We call unpack_index_entry() with an unmerged cache entry
 512 * only in diff-index, and it wants a single callback.  Skip
 513 * the other unmerged entry with the same name.
 514 */
 515static void mark_ce_used_same_name(struct cache_entry *ce,
 516                                   struct unpack_trees_options *o)
 517{
 518        struct index_state *index = o->src_index;
 519        int len = ce_namelen(ce);
 520        int pos;
 521
 522        for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
 523                struct cache_entry *next = index->cache[pos];
 524                if (len != ce_namelen(next) ||
 525                    memcmp(ce->name, next->name, len))
 526                        break;
 527                mark_ce_used(next, o);
 528        }
 529}
 530
 531static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
 532{
 533        const struct index_state *index = o->src_index;
 534        int pos = o->cache_bottom;
 535
 536        while (pos < index->cache_nr) {
 537                struct cache_entry *ce = index->cache[pos];
 538                if (!(ce->ce_flags & CE_UNPACKED))
 539                        return ce;
 540                pos++;
 541        }
 542        return NULL;
 543}
 544
 545static void add_same_unmerged(const struct cache_entry *ce,
 546                              struct unpack_trees_options *o)
 547{
 548        struct index_state *index = o->src_index;
 549        int len = ce_namelen(ce);
 550        int pos = index_name_pos(index, ce->name, len);
 551
 552        if (0 <= pos)
 553                die("programming error in a caller of mark_ce_used_same_name");
 554        for (pos = -pos - 1; pos < index->cache_nr; pos++) {
 555                struct cache_entry *next = index->cache[pos];
 556                if (len != ce_namelen(next) ||
 557                    memcmp(ce->name, next->name, len))
 558                        break;
 559                add_entry(o, next, 0, 0);
 560                mark_ce_used(next, o);
 561        }
 562}
 563
 564static int unpack_index_entry(struct cache_entry *ce,
 565                              struct unpack_trees_options *o)
 566{
 567        const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 568        int ret;
 569
 570        src[0] = ce;
 571
 572        mark_ce_used(ce, o);
 573        if (ce_stage(ce)) {
 574                if (o->skip_unmerged) {
 575                        add_entry(o, ce, 0, 0);
 576                        return 0;
 577                }
 578        }
 579        ret = call_unpack_fn(src, o);
 580        if (ce_stage(ce))
 581                mark_ce_used_same_name(ce, o);
 582        return ret;
 583}
 584
 585static int find_cache_pos(struct traverse_info *, const struct name_entry *);
 586
 587static void restore_cache_bottom(struct traverse_info *info, int bottom)
 588{
 589        struct unpack_trees_options *o = info->data;
 590
 591        if (o->diff_index_cached)
 592                return;
 593        o->cache_bottom = bottom;
 594}
 595
 596static int switch_cache_bottom(struct traverse_info *info)
 597{
 598        struct unpack_trees_options *o = info->data;
 599        int ret, pos;
 600
 601        if (o->diff_index_cached)
 602                return 0;
 603        ret = o->cache_bottom;
 604        pos = find_cache_pos(info->prev, &info->name);
 605
 606        if (pos < -1)
 607                o->cache_bottom = -2 - pos;
 608        else if (pos < 0)
 609                o->cache_bottom = o->src_index->cache_nr;
 610        return ret;
 611}
 612
 613static inline int are_same_oid(struct name_entry *name_j, struct name_entry *name_k)
 614{
 615        return name_j->oid && name_k->oid && !oidcmp(name_j->oid, name_k->oid);
 616}
 617
 618static int traverse_trees_recursive(int n, unsigned long dirmask,
 619                                    unsigned long df_conflicts,
 620                                    struct name_entry *names,
 621                                    struct traverse_info *info)
 622{
 623        int i, ret, bottom;
 624        int nr_buf = 0;
 625        struct tree_desc t[MAX_UNPACK_TREES];
 626        void *buf[MAX_UNPACK_TREES];
 627        struct traverse_info newinfo;
 628        struct name_entry *p;
 629
 630        p = names;
 631        while (!p->mode)
 632                p++;
 633
 634        newinfo = *info;
 635        newinfo.prev = info;
 636        newinfo.pathspec = info->pathspec;
 637        newinfo.name = *p;
 638        newinfo.pathlen += tree_entry_len(p) + 1;
 639        newinfo.df_conflicts |= df_conflicts;
 640
 641        /*
 642         * Fetch the tree from the ODB for each peer directory in the
 643         * n commits.
 644         *
 645         * For 2- and 3-way traversals, we try to avoid hitting the
 646         * ODB twice for the same OID.  This should yield a nice speed
 647         * up in checkouts and merges when the commits are similar.
 648         *
 649         * We don't bother doing the full O(n^2) search for larger n,
 650         * because wider traversals don't happen that often and we
 651         * avoid the search setup.
 652         *
 653         * When 2 peer OIDs are the same, we just copy the tree
 654         * descriptor data.  This implicitly borrows the buffer
 655         * data from the earlier cell.
 656         */
 657        for (i = 0; i < n; i++, dirmask >>= 1) {
 658                if (i > 0 && are_same_oid(&names[i], &names[i - 1]))
 659                        t[i] = t[i - 1];
 660                else if (i > 1 && are_same_oid(&names[i], &names[i - 2]))
 661                        t[i] = t[i - 2];
 662                else {
 663                        const unsigned char *sha1 = NULL;
 664                        if (dirmask & 1)
 665                                sha1 = names[i].oid->hash;
 666                        buf[nr_buf++] = fill_tree_descriptor(t+i, sha1);
 667                }
 668        }
 669
 670        bottom = switch_cache_bottom(&newinfo);
 671        ret = traverse_trees(n, t, &newinfo);
 672        restore_cache_bottom(&newinfo, bottom);
 673
 674        for (i = 0; i < nr_buf; i++)
 675                free(buf[i]);
 676
 677        return ret;
 678}
 679
 680/*
 681 * Compare the traverse-path to the cache entry without actually
 682 * having to generate the textual representation of the traverse
 683 * path.
 684 *
 685 * NOTE! This *only* compares up to the size of the traverse path
 686 * itself - the caller needs to do the final check for the cache
 687 * entry having more data at the end!
 688 */
 689static int do_compare_entry_piecewise(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 690{
 691        int len, pathlen, ce_len;
 692        const char *ce_name;
 693
 694        if (info->prev) {
 695                int cmp = do_compare_entry_piecewise(ce, info->prev,
 696                                                     &info->name);
 697                if (cmp)
 698                        return cmp;
 699        }
 700        pathlen = info->pathlen;
 701        ce_len = ce_namelen(ce);
 702
 703        /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 704        if (ce_len < pathlen)
 705                return -1;
 706
 707        ce_len -= pathlen;
 708        ce_name = ce->name + pathlen;
 709
 710        len = tree_entry_len(n);
 711        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 712}
 713
 714static int do_compare_entry(const struct cache_entry *ce,
 715                            const struct traverse_info *info,
 716                            const struct name_entry *n)
 717{
 718        int len, pathlen, ce_len;
 719        const char *ce_name;
 720        int cmp;
 721
 722        /*
 723         * If we have not precomputed the traverse path, it is quicker
 724         * to avoid doing so.  But if we have precomputed it,
 725         * it is quicker to use the precomputed version.
 726         */
 727        if (!info->traverse_path)
 728                return do_compare_entry_piecewise(ce, info, n);
 729
 730        cmp = strncmp(ce->name, info->traverse_path, info->pathlen);
 731        if (cmp)
 732                return cmp;
 733
 734        pathlen = info->pathlen;
 735        ce_len = ce_namelen(ce);
 736
 737        if (ce_len < pathlen)
 738                return -1;
 739
 740        ce_len -= pathlen;
 741        ce_name = ce->name + pathlen;
 742
 743        len = tree_entry_len(n);
 744        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 745}
 746
 747static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 748{
 749        int cmp = do_compare_entry(ce, info, n);
 750        if (cmp)
 751                return cmp;
 752
 753        /*
 754         * Even if the beginning compared identically, the ce should
 755         * compare as bigger than a directory leading up to it!
 756         */
 757        return ce_namelen(ce) > traverse_path_len(info, n);
 758}
 759
 760static int ce_in_traverse_path(const struct cache_entry *ce,
 761                               const struct traverse_info *info)
 762{
 763        if (!info->prev)
 764                return 1;
 765        if (do_compare_entry(ce, info->prev, &info->name))
 766                return 0;
 767        /*
 768         * If ce (blob) is the same name as the path (which is a tree
 769         * we will be descending into), it won't be inside it.
 770         */
 771        return (info->pathlen < ce_namelen(ce));
 772}
 773
 774static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
 775{
 776        int len = traverse_path_len(info, n);
 777        struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
 778
 779        ce->ce_mode = create_ce_mode(n->mode);
 780        ce->ce_flags = create_ce_flags(stage);
 781        ce->ce_namelen = len;
 782        oidcpy(&ce->oid, n->oid);
 783        make_traverse_path(ce->name, info, n);
 784
 785        return ce;
 786}
 787
 788static int unpack_nondirectories(int n, unsigned long mask,
 789                                 unsigned long dirmask,
 790                                 struct cache_entry **src,
 791                                 const struct name_entry *names,
 792                                 const struct traverse_info *info)
 793{
 794        int i;
 795        struct unpack_trees_options *o = info->data;
 796        unsigned long conflicts = info->df_conflicts | dirmask;
 797
 798        /* Do we have *only* directories? Nothing to do */
 799        if (mask == dirmask && !src[0])
 800                return 0;
 801
 802        /*
 803         * Ok, we've filled in up to any potential index entry in src[0],
 804         * now do the rest.
 805         */
 806        for (i = 0; i < n; i++) {
 807                int stage;
 808                unsigned int bit = 1ul << i;
 809                if (conflicts & bit) {
 810                        src[i + o->merge] = o->df_conflict_entry;
 811                        continue;
 812                }
 813                if (!(mask & bit))
 814                        continue;
 815                if (!o->merge)
 816                        stage = 0;
 817                else if (i + 1 < o->head_idx)
 818                        stage = 1;
 819                else if (i + 1 > o->head_idx)
 820                        stage = 3;
 821                else
 822                        stage = 2;
 823                src[i + o->merge] = create_ce_entry(info, names + i, stage);
 824        }
 825
 826        if (o->merge) {
 827                int rc = call_unpack_fn((const struct cache_entry * const *)src,
 828                                        o);
 829                for (i = 0; i < n; i++) {
 830                        struct cache_entry *ce = src[i + o->merge];
 831                        if (ce != o->df_conflict_entry)
 832                                free(ce);
 833                }
 834                return rc;
 835        }
 836
 837        for (i = 0; i < n; i++)
 838                if (src[i] && src[i] != o->df_conflict_entry)
 839                        if (do_add_entry(o, src[i], 0, 0))
 840                                return -1;
 841
 842        return 0;
 843}
 844
 845static int unpack_failed(struct unpack_trees_options *o, const char *message)
 846{
 847        discard_index(&o->result);
 848        if (!o->gently && !o->exiting_early) {
 849                if (message)
 850                        return error("%s", message);
 851                return -1;
 852        }
 853        return -1;
 854}
 855
 856/*
 857 * The tree traversal is looking at name p.  If we have a matching entry,
 858 * return it.  If name p is a directory in the index, do not return
 859 * anything, as we will want to match it when the traversal descends into
 860 * the directory.
 861 */
 862static int find_cache_pos(struct traverse_info *info,
 863                          const struct name_entry *p)
 864{
 865        int pos;
 866        struct unpack_trees_options *o = info->data;
 867        struct index_state *index = o->src_index;
 868        int pfxlen = info->pathlen;
 869        int p_len = tree_entry_len(p);
 870
 871        for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
 872                const struct cache_entry *ce = index->cache[pos];
 873                const char *ce_name, *ce_slash;
 874                int cmp, ce_len;
 875
 876                if (ce->ce_flags & CE_UNPACKED) {
 877                        /*
 878                         * cache_bottom entry is already unpacked, so
 879                         * we can never match it; don't check it
 880                         * again.
 881                         */
 882                        if (pos == o->cache_bottom)
 883                                ++o->cache_bottom;
 884                        continue;
 885                }
 886                if (!ce_in_traverse_path(ce, info)) {
 887                        /*
 888                         * Check if we can skip future cache checks
 889                         * (because we're already past all possible
 890                         * entries in the traverse path).
 891                         */
 892                        if (info->traverse_path) {
 893                                if (strncmp(ce->name, info->traverse_path,
 894                                            info->pathlen) > 0)
 895                                        break;
 896                        }
 897                        continue;
 898                }
 899                ce_name = ce->name + pfxlen;
 900                ce_slash = strchr(ce_name, '/');
 901                if (ce_slash)
 902                        ce_len = ce_slash - ce_name;
 903                else
 904                        ce_len = ce_namelen(ce) - pfxlen;
 905                cmp = name_compare(p->path, p_len, ce_name, ce_len);
 906                /*
 907                 * Exact match; if we have a directory we need to
 908                 * delay returning it.
 909                 */
 910                if (!cmp)
 911                        return ce_slash ? -2 - pos : pos;
 912                if (0 < cmp)
 913                        continue; /* keep looking */
 914                /*
 915                 * ce_name sorts after p->path; could it be that we
 916                 * have files under p->path directory in the index?
 917                 * E.g.  ce_name == "t-i", and p->path == "t"; we may
 918                 * have "t/a" in the index.
 919                 */
 920                if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
 921                    ce_name[p_len] < '/')
 922                        continue; /* keep looking */
 923                break;
 924        }
 925        return -1;
 926}
 927
 928static struct cache_entry *find_cache_entry(struct traverse_info *info,
 929                                            const struct name_entry *p)
 930{
 931        int pos = find_cache_pos(info, p);
 932        struct unpack_trees_options *o = info->data;
 933
 934        if (0 <= pos)
 935                return o->src_index->cache[pos];
 936        else
 937                return NULL;
 938}
 939
 940static void debug_path(struct traverse_info *info)
 941{
 942        if (info->prev) {
 943                debug_path(info->prev);
 944                if (*info->prev->name.path)
 945                        putchar('/');
 946        }
 947        printf("%s", info->name.path);
 948}
 949
 950static void debug_name_entry(int i, struct name_entry *n)
 951{
 952        printf("ent#%d %06o %s\n", i,
 953               n->path ? n->mode : 0,
 954               n->path ? n->path : "(missing)");
 955}
 956
 957static void debug_unpack_callback(int n,
 958                                  unsigned long mask,
 959                                  unsigned long dirmask,
 960                                  struct name_entry *names,
 961                                  struct traverse_info *info)
 962{
 963        int i;
 964        printf("* unpack mask %lu, dirmask %lu, cnt %d ",
 965               mask, dirmask, n);
 966        debug_path(info);
 967        putchar('\n');
 968        for (i = 0; i < n; i++)
 969                debug_name_entry(i, names + i);
 970}
 971
 972static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
 973{
 974        struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 975        struct unpack_trees_options *o = info->data;
 976        const struct name_entry *p = names;
 977
 978        /* Find first entry with a real name (we could use "mask" too) */
 979        while (!p->mode)
 980                p++;
 981
 982        if (o->debug_unpack)
 983                debug_unpack_callback(n, mask, dirmask, names, info);
 984
 985        /* Are we supposed to look at the index too? */
 986        if (o->merge) {
 987                while (1) {
 988                        int cmp;
 989                        struct cache_entry *ce;
 990
 991                        if (o->diff_index_cached)
 992                                ce = next_cache_entry(o);
 993                        else
 994                                ce = find_cache_entry(info, p);
 995
 996                        if (!ce)
 997                                break;
 998                        cmp = compare_entry(ce, info, p);
 999                        if (cmp < 0) {
1000                                if (unpack_index_entry(ce, o) < 0)
1001                                        return unpack_failed(o, NULL);
1002                                continue;
1003                        }
1004                        if (!cmp) {
1005                                if (ce_stage(ce)) {
1006                                        /*
1007                                         * If we skip unmerged index
1008                                         * entries, we'll skip this
1009                                         * entry *and* the tree
1010                                         * entries associated with it!
1011                                         */
1012                                        if (o->skip_unmerged) {
1013                                                add_same_unmerged(ce, o);
1014                                                return mask;
1015                                        }
1016                                }
1017                                src[0] = ce;
1018                        }
1019                        break;
1020                }
1021        }
1022
1023        if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
1024                return -1;
1025
1026        if (o->merge && src[0]) {
1027                if (ce_stage(src[0]))
1028                        mark_ce_used_same_name(src[0], o);
1029                else
1030                        mark_ce_used(src[0], o);
1031        }
1032
1033        /* Now handle any directories.. */
1034        if (dirmask) {
1035                /* special case: "diff-index --cached" looking at a tree */
1036                if (o->diff_index_cached &&
1037                    n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
1038                        int matches;
1039                        matches = cache_tree_matches_traversal(o->src_index->cache_tree,
1040                                                               names, info);
1041                        /*
1042                         * Everything under the name matches; skip the
1043                         * entire hierarchy.  diff_index_cached codepath
1044                         * special cases D/F conflicts in such a way that
1045                         * it does not do any look-ahead, so this is safe.
1046                         */
1047                        if (matches) {
1048                                o->cache_bottom += matches;
1049                                return mask;
1050                        }
1051                }
1052
1053                if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
1054                                             names, info) < 0)
1055                        return -1;
1056                return mask;
1057        }
1058
1059        return mask;
1060}
1061
1062static int clear_ce_flags_1(struct cache_entry **cache, int nr,
1063                            struct strbuf *prefix,
1064                            int select_mask, int clear_mask,
1065                            struct exclude_list *el, int defval);
1066
1067/* Whole directory matching */
1068static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
1069                              struct strbuf *prefix,
1070                              char *basename,
1071                              int select_mask, int clear_mask,
1072                              struct exclude_list *el, int defval)
1073{
1074        struct cache_entry **cache_end;
1075        int dtype = DT_DIR;
1076        int ret = is_excluded_from_list(prefix->buf, prefix->len,
1077                                        basename, &dtype, el, &the_index);
1078        int rc;
1079
1080        strbuf_addch(prefix, '/');
1081
1082        /* If undecided, use matching result of parent dir in defval */
1083        if (ret < 0)
1084                ret = defval;
1085
1086        for (cache_end = cache; cache_end != cache + nr; cache_end++) {
1087                struct cache_entry *ce = *cache_end;
1088                if (strncmp(ce->name, prefix->buf, prefix->len))
1089                        break;
1090        }
1091
1092        /*
1093         * TODO: check el, if there are no patterns that may conflict
1094         * with ret (iow, we know in advance the incl/excl
1095         * decision for the entire directory), clear flag here without
1096         * calling clear_ce_flags_1(). That function will call
1097         * the expensive is_excluded_from_list() on every entry.
1098         */
1099        rc = clear_ce_flags_1(cache, cache_end - cache,
1100                              prefix,
1101                              select_mask, clear_mask,
1102                              el, ret);
1103        strbuf_setlen(prefix, prefix->len - 1);
1104        return rc;
1105}
1106
1107/*
1108 * Traverse the index, find every entry that matches according to
1109 * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
1110 * number of traversed entries.
1111 *
1112 * If select_mask is non-zero, only entries whose ce_flags has on of
1113 * those bits enabled are traversed.
1114 *
1115 * cache        : pointer to an index entry
1116 * prefix_len   : an offset to its path
1117 *
1118 * The current path ("prefix") including the trailing '/' is
1119 *   cache[0]->name[0..(prefix_len-1)]
1120 * Top level path has prefix_len zero.
1121 */
1122static int clear_ce_flags_1(struct cache_entry **cache, int nr,
1123                            struct strbuf *prefix,
1124                            int select_mask, int clear_mask,
1125                            struct exclude_list *el, int defval)
1126{
1127        struct cache_entry **cache_end = cache + nr;
1128
1129        /*
1130         * Process all entries that have the given prefix and meet
1131         * select_mask condition
1132         */
1133        while(cache != cache_end) {
1134                struct cache_entry *ce = *cache;
1135                const char *name, *slash;
1136                int len, dtype, ret;
1137
1138                if (select_mask && !(ce->ce_flags & select_mask)) {
1139                        cache++;
1140                        continue;
1141                }
1142
1143                if (prefix->len && strncmp(ce->name, prefix->buf, prefix->len))
1144                        break;
1145
1146                name = ce->name + prefix->len;
1147                slash = strchr(name, '/');
1148
1149                /* If it's a directory, try whole directory match first */
1150                if (slash) {
1151                        int processed;
1152
1153                        len = slash - name;
1154                        strbuf_add(prefix, name, len);
1155
1156                        processed = clear_ce_flags_dir(cache, cache_end - cache,
1157                                                       prefix,
1158                                                       prefix->buf + prefix->len - len,
1159                                                       select_mask, clear_mask,
1160                                                       el, defval);
1161
1162                        /* clear_c_f_dir eats a whole dir already? */
1163                        if (processed) {
1164                                cache += processed;
1165                                strbuf_setlen(prefix, prefix->len - len);
1166                                continue;
1167                        }
1168
1169                        strbuf_addch(prefix, '/');
1170                        cache += clear_ce_flags_1(cache, cache_end - cache,
1171                                                  prefix,
1172                                                  select_mask, clear_mask, el, defval);
1173                        strbuf_setlen(prefix, prefix->len - len - 1);
1174                        continue;
1175                }
1176
1177                /* Non-directory */
1178                dtype = ce_to_dtype(ce);
1179                ret = is_excluded_from_list(ce->name, ce_namelen(ce),
1180                                            name, &dtype, el, &the_index);
1181                if (ret < 0)
1182                        ret = defval;
1183                if (ret > 0)
1184                        ce->ce_flags &= ~clear_mask;
1185                cache++;
1186        }
1187        return nr - (cache_end - cache);
1188}
1189
1190static int clear_ce_flags(struct cache_entry **cache, int nr,
1191                            int select_mask, int clear_mask,
1192                            struct exclude_list *el)
1193{
1194        static struct strbuf prefix = STRBUF_INIT;
1195
1196        strbuf_reset(&prefix);
1197
1198        return clear_ce_flags_1(cache, nr,
1199                                &prefix,
1200                                select_mask, clear_mask,
1201                                el, 0);
1202}
1203
1204/*
1205 * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
1206 */
1207static void mark_new_skip_worktree(struct exclude_list *el,
1208                                   struct index_state *the_index,
1209                                   int select_flag, int skip_wt_flag)
1210{
1211        int i;
1212
1213        /*
1214         * 1. Pretend the narrowest worktree: only unmerged entries
1215         * are checked out
1216         */
1217        for (i = 0; i < the_index->cache_nr; i++) {
1218                struct cache_entry *ce = the_index->cache[i];
1219
1220                if (select_flag && !(ce->ce_flags & select_flag))
1221                        continue;
1222
1223                if (!ce_stage(ce))
1224                        ce->ce_flags |= skip_wt_flag;
1225                else
1226                        ce->ce_flags &= ~skip_wt_flag;
1227        }
1228
1229        /*
1230         * 2. Widen worktree according to sparse-checkout file.
1231         * Matched entries will have skip_wt_flag cleared (i.e. "in")
1232         */
1233        clear_ce_flags(the_index->cache, the_index->cache_nr,
1234                       select_flag, skip_wt_flag, el);
1235}
1236
1237static int verify_absent(const struct cache_entry *,
1238                         enum unpack_trees_error_types,
1239                         struct unpack_trees_options *);
1240/*
1241 * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1242 * resulting index, -2 on failure to reflect the changes to the work tree.
1243 *
1244 * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1245 */
1246int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1247{
1248        int i, ret;
1249        static struct cache_entry *dfc;
1250        struct exclude_list el;
1251
1252        if (len > MAX_UNPACK_TREES)
1253                die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1254
1255        memset(&el, 0, sizeof(el));
1256        if (!core_apply_sparse_checkout || !o->update)
1257                o->skip_sparse_checkout = 1;
1258        if (!o->skip_sparse_checkout) {
1259                char *sparse = git_pathdup("info/sparse-checkout");
1260                if (add_excludes_from_file_to_list(sparse, "", 0, &el, NULL) < 0)
1261                        o->skip_sparse_checkout = 1;
1262                else
1263                        o->el = &el;
1264                free(sparse);
1265        }
1266
1267        memset(&o->result, 0, sizeof(o->result));
1268        o->result.initialized = 1;
1269        o->result.timestamp.sec = o->src_index->timestamp.sec;
1270        o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1271        o->result.version = o->src_index->version;
1272        o->result.split_index = o->src_index->split_index;
1273        if (o->result.split_index)
1274                o->result.split_index->refcount++;
1275        hashcpy(o->result.sha1, o->src_index->sha1);
1276        o->merge_size = len;
1277        mark_all_ce_unused(o->src_index);
1278
1279        /*
1280         * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1281         */
1282        if (!o->skip_sparse_checkout)
1283                mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1284
1285        if (!dfc)
1286                dfc = xcalloc(1, cache_entry_size(0));
1287        o->df_conflict_entry = dfc;
1288
1289        if (len) {
1290                const char *prefix = o->prefix ? o->prefix : "";
1291                struct traverse_info info;
1292
1293                setup_traverse_info(&info, prefix);
1294                info.fn = unpack_callback;
1295                info.data = o;
1296                info.show_all_errors = o->show_all_errors;
1297                info.pathspec = o->pathspec;
1298
1299                if (o->prefix) {
1300                        /*
1301                         * Unpack existing index entries that sort before the
1302                         * prefix the tree is spliced into.  Note that o->merge
1303                         * is always true in this case.
1304                         */
1305                        while (1) {
1306                                struct cache_entry *ce = next_cache_entry(o);
1307                                if (!ce)
1308                                        break;
1309                                if (ce_in_traverse_path(ce, &info))
1310                                        break;
1311                                if (unpack_index_entry(ce, o) < 0)
1312                                        goto return_failed;
1313                        }
1314                }
1315
1316                if (traverse_trees(len, t, &info) < 0)
1317                        goto return_failed;
1318        }
1319
1320        /* Any left-over entries in the index? */
1321        if (o->merge) {
1322                while (1) {
1323                        struct cache_entry *ce = next_cache_entry(o);
1324                        if (!ce)
1325                                break;
1326                        if (unpack_index_entry(ce, o) < 0)
1327                                goto return_failed;
1328                }
1329        }
1330        mark_all_ce_unused(o->src_index);
1331
1332        if (o->trivial_merges_only && o->nontrivial_merge) {
1333                ret = unpack_failed(o, "Merge requires file-level merging");
1334                goto done;
1335        }
1336
1337        if (!o->skip_sparse_checkout) {
1338                int empty_worktree = 1;
1339
1340                /*
1341                 * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1342                 * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1343                 * so apply_sparse_checkout() won't attempt to remove it from worktree
1344                 */
1345                mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1346
1347                ret = 0;
1348                for (i = 0; i < o->result.cache_nr; i++) {
1349                        struct cache_entry *ce = o->result.cache[i];
1350
1351                        /*
1352                         * Entries marked with CE_ADDED in merged_entry() do not have
1353                         * verify_absent() check (the check is effectively disabled
1354                         * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1355                         *
1356                         * Do the real check now because we have had
1357                         * correct CE_NEW_SKIP_WORKTREE
1358                         */
1359                        if (ce->ce_flags & CE_ADDED &&
1360                            verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1361                                if (!o->show_all_errors)
1362                                        goto return_failed;
1363                                ret = -1;
1364                        }
1365
1366                        if (apply_sparse_checkout(&o->result, ce, o)) {
1367                                if (!o->show_all_errors)
1368                                        goto return_failed;
1369                                ret = -1;
1370                        }
1371                        if (!ce_skip_worktree(ce))
1372                                empty_worktree = 0;
1373
1374                }
1375                if (ret < 0)
1376                        goto return_failed;
1377                /*
1378                 * Sparse checkout is meant to narrow down checkout area
1379                 * but it does not make sense to narrow down to empty working
1380                 * tree. This is usually a mistake in sparse checkout rules.
1381                 * Do not allow users to do that.
1382                 */
1383                if (o->result.cache_nr && empty_worktree) {
1384                        ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1385                        goto done;
1386                }
1387        }
1388
1389        o->src_index = NULL;
1390        ret = check_updates(o) ? (-2) : 0;
1391        if (o->dst_index) {
1392                if (!ret) {
1393                        if (!o->result.cache_tree)
1394                                o->result.cache_tree = cache_tree();
1395                        if (!cache_tree_fully_valid(o->result.cache_tree))
1396                                cache_tree_update(&o->result,
1397                                                  WRITE_TREE_SILENT |
1398                                                  WRITE_TREE_REPAIR);
1399                }
1400                move_index_extensions(&o->result, o->dst_index);
1401                discard_index(o->dst_index);
1402                *o->dst_index = o->result;
1403        } else {
1404                discard_index(&o->result);
1405        }
1406
1407done:
1408        clear_exclude_list(&el);
1409        return ret;
1410
1411return_failed:
1412        if (o->show_all_errors)
1413                display_error_msgs(o);
1414        mark_all_ce_unused(o->src_index);
1415        ret = unpack_failed(o, NULL);
1416        if (o->exiting_early)
1417                ret = 0;
1418        goto done;
1419}
1420
1421/* Here come the merge functions */
1422
1423static int reject_merge(const struct cache_entry *ce,
1424                        struct unpack_trees_options *o)
1425{
1426        return o->gently ? -1 :
1427                add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1428}
1429
1430static int same(const struct cache_entry *a, const struct cache_entry *b)
1431{
1432        if (!!a != !!b)
1433                return 0;
1434        if (!a && !b)
1435                return 1;
1436        if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1437                return 0;
1438        return a->ce_mode == b->ce_mode &&
1439               !oidcmp(&a->oid, &b->oid);
1440}
1441
1442
1443/*
1444 * When a CE gets turned into an unmerged entry, we
1445 * want it to be up-to-date
1446 */
1447static int verify_uptodate_1(const struct cache_entry *ce,
1448                             struct unpack_trees_options *o,
1449                             enum unpack_trees_error_types error_type)
1450{
1451        struct stat st;
1452
1453        if (o->index_only)
1454                return 0;
1455
1456        /*
1457         * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1458         * if this entry is truly up-to-date because this file may be
1459         * overwritten.
1460         */
1461        if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1462                ; /* keep checking */
1463        else if (o->reset || ce_uptodate(ce))
1464                return 0;
1465
1466        if (!lstat(ce->name, &st)) {
1467                int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1468                unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1469
1470                if (submodule_from_ce(ce)) {
1471                        int r = check_submodule_move_head(ce,
1472                                "HEAD", oid_to_hex(&ce->oid), o);
1473                        if (r)
1474                                return o->gently ? -1 :
1475                                        add_rejected_path(o, error_type, ce->name);
1476                        return 0;
1477                }
1478
1479                if (!changed)
1480                        return 0;
1481                /*
1482                 * Historic default policy was to allow submodule to be out
1483                 * of sync wrt the superproject index. If the submodule was
1484                 * not considered interesting above, we don't care here.
1485                 */
1486                if (S_ISGITLINK(ce->ce_mode))
1487                        return 0;
1488
1489                errno = 0;
1490        }
1491        if (errno == ENOENT)
1492                return 0;
1493        return o->gently ? -1 :
1494                add_rejected_path(o, error_type, ce->name);
1495}
1496
1497static int verify_uptodate(const struct cache_entry *ce,
1498                           struct unpack_trees_options *o)
1499{
1500        if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1501                return 0;
1502        return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1503}
1504
1505static int verify_uptodate_sparse(const struct cache_entry *ce,
1506                                  struct unpack_trees_options *o)
1507{
1508        return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1509}
1510
1511static void invalidate_ce_path(const struct cache_entry *ce,
1512                               struct unpack_trees_options *o)
1513{
1514        if (!ce)
1515                return;
1516        cache_tree_invalidate_path(o->src_index, ce->name);
1517        untracked_cache_invalidate_path(o->src_index, ce->name);
1518}
1519
1520/*
1521 * Check that checking out ce->sha1 in subdir ce->name is not
1522 * going to overwrite any working files.
1523 *
1524 * Currently, git does not checkout subprojects during a superproject
1525 * checkout, so it is not going to overwrite anything.
1526 */
1527static int verify_clean_submodule(const char *old_sha1,
1528                                  const struct cache_entry *ce,
1529                                  enum unpack_trees_error_types error_type,
1530                                  struct unpack_trees_options *o)
1531{
1532        if (!submodule_from_ce(ce))
1533                return 0;
1534
1535        return check_submodule_move_head(ce, old_sha1,
1536                                         oid_to_hex(&ce->oid), o);
1537}
1538
1539static int verify_clean_subdirectory(const struct cache_entry *ce,
1540                                     enum unpack_trees_error_types error_type,
1541                                     struct unpack_trees_options *o)
1542{
1543        /*
1544         * we are about to extract "ce->name"; we would not want to lose
1545         * anything in the existing directory there.
1546         */
1547        int namelen;
1548        int i;
1549        struct dir_struct d;
1550        char *pathbuf;
1551        int cnt = 0;
1552
1553        if (S_ISGITLINK(ce->ce_mode)) {
1554                unsigned char sha1[20];
1555                int sub_head = resolve_gitlink_ref(ce->name, "HEAD", sha1);
1556                /*
1557                 * If we are not going to update the submodule, then
1558                 * we don't care.
1559                 */
1560                if (!sub_head && !hashcmp(sha1, ce->oid.hash))
1561                        return 0;
1562                return verify_clean_submodule(sub_head ? NULL : sha1_to_hex(sha1),
1563                                              ce, error_type, o);
1564        }
1565
1566        /*
1567         * First let's make sure we do not have a local modification
1568         * in that directory.
1569         */
1570        namelen = ce_namelen(ce);
1571        for (i = locate_in_src_index(ce, o);
1572             i < o->src_index->cache_nr;
1573             i++) {
1574                struct cache_entry *ce2 = o->src_index->cache[i];
1575                int len = ce_namelen(ce2);
1576                if (len < namelen ||
1577                    strncmp(ce->name, ce2->name, namelen) ||
1578                    ce2->name[namelen] != '/')
1579                        break;
1580                /*
1581                 * ce2->name is an entry in the subdirectory to be
1582                 * removed.
1583                 */
1584                if (!ce_stage(ce2)) {
1585                        if (verify_uptodate(ce2, o))
1586                                return -1;
1587                        add_entry(o, ce2, CE_REMOVE, 0);
1588                        mark_ce_used(ce2, o);
1589                }
1590                cnt++;
1591        }
1592
1593        /*
1594         * Then we need to make sure that we do not lose a locally
1595         * present file that is not ignored.
1596         */
1597        pathbuf = xstrfmt("%.*s/", namelen, ce->name);
1598
1599        memset(&d, 0, sizeof(d));
1600        if (o->dir)
1601                d.exclude_per_dir = o->dir->exclude_per_dir;
1602        i = read_directory(&d, &the_index, pathbuf, namelen+1, NULL);
1603        if (i)
1604                return o->gently ? -1 :
1605                        add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1606        free(pathbuf);
1607        return cnt;
1608}
1609
1610/*
1611 * This gets called when there was no index entry for the tree entry 'dst',
1612 * but we found a file in the working tree that 'lstat()' said was fine,
1613 * and we're on a case-insensitive filesystem.
1614 *
1615 * See if we can find a case-insensitive match in the index that also
1616 * matches the stat information, and assume it's that other file!
1617 */
1618static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1619{
1620        const struct cache_entry *src;
1621
1622        src = index_file_exists(o->src_index, name, len, 1);
1623        return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1624}
1625
1626static int check_ok_to_remove(const char *name, int len, int dtype,
1627                              const struct cache_entry *ce, struct stat *st,
1628                              enum unpack_trees_error_types error_type,
1629                              struct unpack_trees_options *o)
1630{
1631        const struct cache_entry *result;
1632
1633        /*
1634         * It may be that the 'lstat()' succeeded even though
1635         * target 'ce' was absent, because there is an old
1636         * entry that is different only in case..
1637         *
1638         * Ignore that lstat() if it matches.
1639         */
1640        if (ignore_case && icase_exists(o, name, len, st))
1641                return 0;
1642
1643        if (o->dir &&
1644            is_excluded(o->dir, &the_index, name, &dtype))
1645                /*
1646                 * ce->name is explicitly excluded, so it is Ok to
1647                 * overwrite it.
1648                 */
1649                return 0;
1650        if (S_ISDIR(st->st_mode)) {
1651                /*
1652                 * We are checking out path "foo" and
1653                 * found "foo/." in the working tree.
1654                 * This is tricky -- if we have modified
1655                 * files that are in "foo/" we would lose
1656                 * them.
1657                 */
1658                if (verify_clean_subdirectory(ce, error_type, o) < 0)
1659                        return -1;
1660                return 0;
1661        }
1662
1663        /*
1664         * The previous round may already have decided to
1665         * delete this path, which is in a subdirectory that
1666         * is being replaced with a blob.
1667         */
1668        result = index_file_exists(&o->result, name, len, 0);
1669        if (result) {
1670                if (result->ce_flags & CE_REMOVE)
1671                        return 0;
1672        }
1673
1674        return o->gently ? -1 :
1675                add_rejected_path(o, error_type, name);
1676}
1677
1678/*
1679 * We do not want to remove or overwrite a working tree file that
1680 * is not tracked, unless it is ignored.
1681 */
1682static int verify_absent_1(const struct cache_entry *ce,
1683                           enum unpack_trees_error_types error_type,
1684                           struct unpack_trees_options *o)
1685{
1686        int len;
1687        struct stat st;
1688
1689        if (o->index_only || o->reset || !o->update)
1690                return 0;
1691
1692        len = check_leading_path(ce->name, ce_namelen(ce));
1693        if (!len)
1694                return 0;
1695        else if (len > 0) {
1696                char *path;
1697                int ret;
1698
1699                path = xmemdupz(ce->name, len);
1700                if (lstat(path, &st))
1701                        ret = error_errno("cannot stat '%s'", path);
1702                else {
1703                        if (submodule_from_ce(ce))
1704                                ret = check_submodule_move_head(ce,
1705                                                                oid_to_hex(&ce->oid),
1706                                                                NULL, o);
1707                        else
1708                                ret = check_ok_to_remove(path, len, DT_UNKNOWN, NULL,
1709                                                         &st, error_type, o);
1710                }
1711                free(path);
1712                return ret;
1713        } else if (lstat(ce->name, &st)) {
1714                if (errno != ENOENT)
1715                        return error_errno("cannot stat '%s'", ce->name);
1716                return 0;
1717        } else {
1718                if (submodule_from_ce(ce))
1719                        return check_submodule_move_head(ce, oid_to_hex(&ce->oid),
1720                                                         NULL, o);
1721
1722                return check_ok_to_remove(ce->name, ce_namelen(ce),
1723                                          ce_to_dtype(ce), ce, &st,
1724                                          error_type, o);
1725        }
1726}
1727
1728static int verify_absent(const struct cache_entry *ce,
1729                         enum unpack_trees_error_types error_type,
1730                         struct unpack_trees_options *o)
1731{
1732        if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1733                return 0;
1734        return verify_absent_1(ce, error_type, o);
1735}
1736
1737static int verify_absent_sparse(const struct cache_entry *ce,
1738                                enum unpack_trees_error_types error_type,
1739                                struct unpack_trees_options *o)
1740{
1741        enum unpack_trees_error_types orphaned_error = error_type;
1742        if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1743                orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1744
1745        return verify_absent_1(ce, orphaned_error, o);
1746}
1747
1748static int merged_entry(const struct cache_entry *ce,
1749                        const struct cache_entry *old,
1750                        struct unpack_trees_options *o)
1751{
1752        int update = CE_UPDATE;
1753        struct cache_entry *merge = dup_entry(ce);
1754
1755        if (!old) {
1756                /*
1757                 * New index entries. In sparse checkout, the following
1758                 * verify_absent() will be delayed until after
1759                 * traverse_trees() finishes in unpack_trees(), then:
1760                 *
1761                 *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1762                 *  - verify_absent() be called again, this time with
1763                 *    correct CE_NEW_SKIP_WORKTREE
1764                 *
1765                 * verify_absent() call here does nothing in sparse
1766                 * checkout (i.e. o->skip_sparse_checkout == 0)
1767                 */
1768                update |= CE_ADDED;
1769                merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1770
1771                if (verify_absent(merge,
1772                                  ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1773                        free(merge);
1774                        return -1;
1775                }
1776                invalidate_ce_path(merge, o);
1777
1778                if (submodule_from_ce(ce)) {
1779                        int ret = check_submodule_move_head(ce, NULL,
1780                                                            oid_to_hex(&ce->oid),
1781                                                            o);
1782                        if (ret)
1783                                return ret;
1784                }
1785
1786        } else if (!(old->ce_flags & CE_CONFLICTED)) {
1787                /*
1788                 * See if we can re-use the old CE directly?
1789                 * That way we get the uptodate stat info.
1790                 *
1791                 * This also removes the UPDATE flag on a match; otherwise
1792                 * we will end up overwriting local changes in the work tree.
1793                 */
1794                if (same(old, merge)) {
1795                        copy_cache_entry(merge, old);
1796                        update = 0;
1797                } else {
1798                        if (verify_uptodate(old, o)) {
1799                                free(merge);
1800                                return -1;
1801                        }
1802                        /* Migrate old flags over */
1803                        update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1804                        invalidate_ce_path(old, o);
1805                }
1806
1807                if (submodule_from_ce(ce)) {
1808                        int ret = check_submodule_move_head(ce, oid_to_hex(&old->oid),
1809                                                            oid_to_hex(&ce->oid),
1810                                                            o);
1811                        if (ret)
1812                                return ret;
1813                }
1814        } else {
1815                /*
1816                 * Previously unmerged entry left as an existence
1817                 * marker by read_index_unmerged();
1818                 */
1819                invalidate_ce_path(old, o);
1820        }
1821
1822        do_add_entry(o, merge, update, CE_STAGEMASK);
1823        return 1;
1824}
1825
1826static int deleted_entry(const struct cache_entry *ce,
1827                         const struct cache_entry *old,
1828                         struct unpack_trees_options *o)
1829{
1830        /* Did it exist in the index? */
1831        if (!old) {
1832                if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1833                        return -1;
1834                return 0;
1835        }
1836        if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1837                return -1;
1838        add_entry(o, ce, CE_REMOVE, 0);
1839        invalidate_ce_path(ce, o);
1840        return 1;
1841}
1842
1843static int keep_entry(const struct cache_entry *ce,
1844                      struct unpack_trees_options *o)
1845{
1846        add_entry(o, ce, 0, 0);
1847        return 1;
1848}
1849
1850#if DBRT_DEBUG
1851static void show_stage_entry(FILE *o,
1852                             const char *label, const struct cache_entry *ce)
1853{
1854        if (!ce)
1855                fprintf(o, "%s (missing)\n", label);
1856        else
1857                fprintf(o, "%s%06o %s %d\t%s\n",
1858                        label,
1859                        ce->ce_mode,
1860                        oid_to_hex(&ce->oid),
1861                        ce_stage(ce),
1862                        ce->name);
1863}
1864#endif
1865
1866int threeway_merge(const struct cache_entry * const *stages,
1867                   struct unpack_trees_options *o)
1868{
1869        const struct cache_entry *index;
1870        const struct cache_entry *head;
1871        const struct cache_entry *remote = stages[o->head_idx + 1];
1872        int count;
1873        int head_match = 0;
1874        int remote_match = 0;
1875
1876        int df_conflict_head = 0;
1877        int df_conflict_remote = 0;
1878
1879        int any_anc_missing = 0;
1880        int no_anc_exists = 1;
1881        int i;
1882
1883        for (i = 1; i < o->head_idx; i++) {
1884                if (!stages[i] || stages[i] == o->df_conflict_entry)
1885                        any_anc_missing = 1;
1886                else
1887                        no_anc_exists = 0;
1888        }
1889
1890        index = stages[0];
1891        head = stages[o->head_idx];
1892
1893        if (head == o->df_conflict_entry) {
1894                df_conflict_head = 1;
1895                head = NULL;
1896        }
1897
1898        if (remote == o->df_conflict_entry) {
1899                df_conflict_remote = 1;
1900                remote = NULL;
1901        }
1902
1903        /*
1904         * First, if there's a #16 situation, note that to prevent #13
1905         * and #14.
1906         */
1907        if (!same(remote, head)) {
1908                for (i = 1; i < o->head_idx; i++) {
1909                        if (same(stages[i], head)) {
1910                                head_match = i;
1911                        }
1912                        if (same(stages[i], remote)) {
1913                                remote_match = i;
1914                        }
1915                }
1916        }
1917
1918        /*
1919         * We start with cases where the index is allowed to match
1920         * something other than the head: #14(ALT) and #2ALT, where it
1921         * is permitted to match the result instead.
1922         */
1923        /* #14, #14ALT, #2ALT */
1924        if (remote && !df_conflict_head && head_match && !remote_match) {
1925                if (index && !same(index, remote) && !same(index, head))
1926                        return reject_merge(index, o);
1927                return merged_entry(remote, index, o);
1928        }
1929        /*
1930         * If we have an entry in the index cache, then we want to
1931         * make sure that it matches head.
1932         */
1933        if (index && !same(index, head))
1934                return reject_merge(index, o);
1935
1936        if (head) {
1937                /* #5ALT, #15 */
1938                if (same(head, remote))
1939                        return merged_entry(head, index, o);
1940                /* #13, #3ALT */
1941                if (!df_conflict_remote && remote_match && !head_match)
1942                        return merged_entry(head, index, o);
1943        }
1944
1945        /* #1 */
1946        if (!head && !remote && any_anc_missing)
1947                return 0;
1948
1949        /*
1950         * Under the "aggressive" rule, we resolve mostly trivial
1951         * cases that we historically had git-merge-one-file resolve.
1952         */
1953        if (o->aggressive) {
1954                int head_deleted = !head;
1955                int remote_deleted = !remote;
1956                const struct cache_entry *ce = NULL;
1957
1958                if (index)
1959                        ce = index;
1960                else if (head)
1961                        ce = head;
1962                else if (remote)
1963                        ce = remote;
1964                else {
1965                        for (i = 1; i < o->head_idx; i++) {
1966                                if (stages[i] && stages[i] != o->df_conflict_entry) {
1967                                        ce = stages[i];
1968                                        break;
1969                                }
1970                        }
1971                }
1972
1973                /*
1974                 * Deleted in both.
1975                 * Deleted in one and unchanged in the other.
1976                 */
1977                if ((head_deleted && remote_deleted) ||
1978                    (head_deleted && remote && remote_match) ||
1979                    (remote_deleted && head && head_match)) {
1980                        if (index)
1981                                return deleted_entry(index, index, o);
1982                        if (ce && !head_deleted) {
1983                                if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1984                                        return -1;
1985                        }
1986                        return 0;
1987                }
1988                /*
1989                 * Added in both, identically.
1990                 */
1991                if (no_anc_exists && head && remote && same(head, remote))
1992                        return merged_entry(head, index, o);
1993
1994        }
1995
1996        /* Below are "no merge" cases, which require that the index be
1997         * up-to-date to avoid the files getting overwritten with
1998         * conflict resolution files.
1999         */
2000        if (index) {
2001                if (verify_uptodate(index, o))
2002                        return -1;
2003        }
2004
2005        o->nontrivial_merge = 1;
2006
2007        /* #2, #3, #4, #6, #7, #9, #10, #11. */
2008        count = 0;
2009        if (!head_match || !remote_match) {
2010                for (i = 1; i < o->head_idx; i++) {
2011                        if (stages[i] && stages[i] != o->df_conflict_entry) {
2012                                keep_entry(stages[i], o);
2013                                count++;
2014                                break;
2015                        }
2016                }
2017        }
2018#if DBRT_DEBUG
2019        else {
2020                fprintf(stderr, "read-tree: warning #16 detected\n");
2021                show_stage_entry(stderr, "head   ", stages[head_match]);
2022                show_stage_entry(stderr, "remote ", stages[remote_match]);
2023        }
2024#endif
2025        if (head) { count += keep_entry(head, o); }
2026        if (remote) { count += keep_entry(remote, o); }
2027        return count;
2028}
2029
2030/*
2031 * Two-way merge.
2032 *
2033 * The rule is to "carry forward" what is in the index without losing
2034 * information across a "fast-forward", favoring a successful merge
2035 * over a merge failure when it makes sense.  For details of the
2036 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
2037 *
2038 */
2039int twoway_merge(const struct cache_entry * const *src,
2040                 struct unpack_trees_options *o)
2041{
2042        const struct cache_entry *current = src[0];
2043        const struct cache_entry *oldtree = src[1];
2044        const struct cache_entry *newtree = src[2];
2045
2046        if (o->merge_size != 2)
2047                return error("Cannot do a twoway merge of %d trees",
2048                             o->merge_size);
2049
2050        if (oldtree == o->df_conflict_entry)
2051                oldtree = NULL;
2052        if (newtree == o->df_conflict_entry)
2053                newtree = NULL;
2054
2055        if (current) {
2056                if (current->ce_flags & CE_CONFLICTED) {
2057                        if (same(oldtree, newtree) || o->reset) {
2058                                if (!newtree)
2059                                        return deleted_entry(current, current, o);
2060                                else
2061                                        return merged_entry(newtree, current, o);
2062                        }
2063                        return reject_merge(current, o);
2064                } else if ((!oldtree && !newtree) || /* 4 and 5 */
2065                         (!oldtree && newtree &&
2066                          same(current, newtree)) || /* 6 and 7 */
2067                         (oldtree && newtree &&
2068                          same(oldtree, newtree)) || /* 14 and 15 */
2069                         (oldtree && newtree &&
2070                          !same(oldtree, newtree) && /* 18 and 19 */
2071                          same(current, newtree))) {
2072                        return keep_entry(current, o);
2073                } else if (oldtree && !newtree && same(current, oldtree)) {
2074                        /* 10 or 11 */
2075                        return deleted_entry(oldtree, current, o);
2076                } else if (oldtree && newtree &&
2077                         same(current, oldtree) && !same(current, newtree)) {
2078                        /* 20 or 21 */
2079                        return merged_entry(newtree, current, o);
2080                } else
2081                        return reject_merge(current, o);
2082        }
2083        else if (newtree) {
2084                if (oldtree && !o->initial_checkout) {
2085                        /*
2086                         * deletion of the path was staged;
2087                         */
2088                        if (same(oldtree, newtree))
2089                                return 1;
2090                        return reject_merge(oldtree, o);
2091                }
2092                return merged_entry(newtree, current, o);
2093        }
2094        return deleted_entry(oldtree, current, o);
2095}
2096
2097/*
2098 * Bind merge.
2099 *
2100 * Keep the index entries at stage0, collapse stage1 but make sure
2101 * stage0 does not have anything there.
2102 */
2103int bind_merge(const struct cache_entry * const *src,
2104               struct unpack_trees_options *o)
2105{
2106        const struct cache_entry *old = src[0];
2107        const struct cache_entry *a = src[1];
2108
2109        if (o->merge_size != 1)
2110                return error("Cannot do a bind merge of %d trees",
2111                             o->merge_size);
2112        if (a && old)
2113                return o->gently ? -1 :
2114                        error(ERRORMSG(o, ERROR_BIND_OVERLAP),
2115                              super_prefixed(a->name),
2116                              super_prefixed(old->name));
2117        if (!a)
2118                return keep_entry(old, o);
2119        else
2120                return merged_entry(a, NULL, o);
2121}
2122
2123/*
2124 * One-way merge.
2125 *
2126 * The rule is:
2127 * - take the stat information from stage0, take the data from stage1
2128 */
2129int oneway_merge(const struct cache_entry * const *src,
2130                 struct unpack_trees_options *o)
2131{
2132        const struct cache_entry *old = src[0];
2133        const struct cache_entry *a = src[1];
2134
2135        if (o->merge_size != 1)
2136                return error("Cannot do a oneway merge of %d trees",
2137                             o->merge_size);
2138
2139        if (!a || a == o->df_conflict_entry)
2140                return deleted_entry(old, old, o);
2141
2142        if (old && same(old, a)) {
2143                int update = 0;
2144                if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
2145                        struct stat st;
2146                        if (lstat(old->name, &st) ||
2147                            ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
2148                                update |= CE_UPDATE;
2149                }
2150                add_entry(o, old, update, 0);
2151                return 0;
2152        }
2153        return merged_entry(a, old, o);
2154}