unpack-trees.con commit Merge branch 'maint-1.7.1' into maint-1.7.2 (2de132f)
   1#define NO_THE_INDEX_COMPATIBILITY_MACROS
   2#include "cache.h"
   3#include "dir.h"
   4#include "tree.h"
   5#include "tree-walk.h"
   6#include "cache-tree.h"
   7#include "unpack-trees.h"
   8#include "progress.h"
   9#include "refs.h"
  10#include "attr.h"
  11
  12/*
  13 * Error messages expected by scripts out of plumbing commands such as
  14 * read-tree.  Non-scripted Porcelain is not required to use these messages
  15 * and in fact are encouraged to reword them to better suit their particular
  16 * situation better.  See how "git checkout" replaces not_uptodate_file to
  17 * explain why it does not allow switching between branches when you have
  18 * local changes, for example.
  19 */
  20static struct unpack_trees_error_msgs unpack_plumbing_errors = {
  21        /* would_overwrite */
  22        "Entry '%s' would be overwritten by merge. Cannot merge.",
  23
  24        /* not_uptodate_file */
  25        "Entry '%s' not uptodate. Cannot merge.",
  26
  27        /* not_uptodate_dir */
  28        "Updating '%s' would lose untracked files in it",
  29
  30        /* would_lose_untracked */
  31        "Untracked working tree file '%s' would be %s by merge.",
  32
  33        /* bind_overlap */
  34        "Entry '%s' overlaps with '%s'.  Cannot bind.",
  35
  36        /* sparse_not_uptodate_file */
  37        "Entry '%s' not uptodate. Cannot update sparse checkout.",
  38
  39        /* would_lose_orphaned */
  40        "Working tree file '%s' would be %s by sparse checkout update.",
  41};
  42
  43#define ERRORMSG(o,fld) \
  44        ( ((o) && (o)->msgs.fld) \
  45        ? ((o)->msgs.fld) \
  46        : (unpack_plumbing_errors.fld) )
  47
  48static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
  49        unsigned int set, unsigned int clear)
  50{
  51        unsigned int size = ce_size(ce);
  52        struct cache_entry *new = xmalloc(size);
  53
  54        clear |= CE_HASHED | CE_UNHASHED;
  55
  56        memcpy(new, ce, size);
  57        new->next = NULL;
  58        new->ce_flags = (new->ce_flags & ~clear) | set;
  59        add_index_entry(&o->result, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
  60}
  61
  62/*
  63 * Unlink the last component and schedule the leading directories for
  64 * removal, such that empty directories get removed.
  65 */
  66static void unlink_entry(struct cache_entry *ce)
  67{
  68        if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
  69                return;
  70        if (remove_or_warn(ce->ce_mode, ce->name))
  71                return;
  72        schedule_dir_for_removal(ce->name, ce_namelen(ce));
  73}
  74
  75static struct checkout state;
  76static int check_updates(struct unpack_trees_options *o)
  77{
  78        unsigned cnt = 0, total = 0;
  79        struct progress *progress = NULL;
  80        struct index_state *index = &o->result;
  81        int i;
  82        int errs = 0;
  83
  84        if (o->update && o->verbose_update) {
  85                for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
  86                        struct cache_entry *ce = index->cache[cnt];
  87                        if (ce->ce_flags & (CE_UPDATE | CE_REMOVE | CE_WT_REMOVE))
  88                                total++;
  89                }
  90
  91                progress = start_progress_delay("Checking out files",
  92                                                total, 50, 1);
  93                cnt = 0;
  94        }
  95
  96        if (o->update)
  97                git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
  98        for (i = 0; i < index->cache_nr; i++) {
  99                struct cache_entry *ce = index->cache[i];
 100
 101                if (ce->ce_flags & CE_WT_REMOVE) {
 102                        display_progress(progress, ++cnt);
 103                        if (o->update)
 104                                unlink_entry(ce);
 105                        continue;
 106                }
 107
 108                if (ce->ce_flags & CE_REMOVE) {
 109                        display_progress(progress, ++cnt);
 110                        if (o->update)
 111                                unlink_entry(ce);
 112                }
 113        }
 114        remove_marked_cache_entries(&o->result);
 115        remove_scheduled_dirs();
 116
 117        for (i = 0; i < index->cache_nr; i++) {
 118                struct cache_entry *ce = index->cache[i];
 119
 120                if (ce->ce_flags & CE_UPDATE) {
 121                        display_progress(progress, ++cnt);
 122                        ce->ce_flags &= ~CE_UPDATE;
 123                        if (o->update) {
 124                                errs |= checkout_entry(ce, &state, NULL);
 125                        }
 126                }
 127        }
 128        stop_progress(&progress);
 129        if (o->update)
 130                git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
 131        return errs != 0;
 132}
 133
 134static int verify_uptodate_sparse(struct cache_entry *ce, struct unpack_trees_options *o);
 135static int verify_absent_sparse(struct cache_entry *ce, const char *action, struct unpack_trees_options *o);
 136
 137static int will_have_skip_worktree(const struct cache_entry *ce, struct unpack_trees_options *o)
 138{
 139        const char *basename;
 140
 141        if (ce_stage(ce))
 142                return 0;
 143
 144        basename = strrchr(ce->name, '/');
 145        basename = basename ? basename+1 : ce->name;
 146        return excluded_from_list(ce->name, ce_namelen(ce), basename, NULL, o->el) <= 0;
 147}
 148
 149static int apply_sparse_checkout(struct cache_entry *ce, struct unpack_trees_options *o)
 150{
 151        int was_skip_worktree = ce_skip_worktree(ce);
 152
 153        if (will_have_skip_worktree(ce, o))
 154                ce->ce_flags |= CE_SKIP_WORKTREE;
 155        else
 156                ce->ce_flags &= ~CE_SKIP_WORKTREE;
 157
 158        /*
 159         * We only care about files getting into the checkout area
 160         * If merge strategies want to remove some, go ahead, this
 161         * flag will be removed eventually in unpack_trees() if it's
 162         * outside checkout area.
 163         */
 164        if (ce->ce_flags & CE_REMOVE)
 165                return 0;
 166
 167        if (!was_skip_worktree && ce_skip_worktree(ce)) {
 168                /*
 169                 * If CE_UPDATE is set, verify_uptodate() must be called already
 170                 * also stat info may have lost after merged_entry() so calling
 171                 * verify_uptodate() again may fail
 172                 */
 173                if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
 174                        return -1;
 175                ce->ce_flags |= CE_WT_REMOVE;
 176        }
 177        if (was_skip_worktree && !ce_skip_worktree(ce)) {
 178                if (verify_absent_sparse(ce, "overwritten", o))
 179                        return -1;
 180                ce->ce_flags |= CE_UPDATE;
 181        }
 182        return 0;
 183}
 184
 185static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
 186{
 187        int ret = o->fn(src, o);
 188        if (ret > 0)
 189                ret = 0;
 190        return ret;
 191}
 192
 193static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
 194{
 195        ce->ce_flags |= CE_UNPACKED;
 196
 197        if (o->cache_bottom < o->src_index->cache_nr &&
 198            o->src_index->cache[o->cache_bottom] == ce) {
 199                int bottom = o->cache_bottom;
 200                while (bottom < o->src_index->cache_nr &&
 201                       o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
 202                        bottom++;
 203                o->cache_bottom = bottom;
 204        }
 205}
 206
 207static void mark_all_ce_unused(struct index_state *index)
 208{
 209        int i;
 210        for (i = 0; i < index->cache_nr; i++)
 211                index->cache[i]->ce_flags &= ~CE_UNPACKED;
 212}
 213
 214static int locate_in_src_index(struct cache_entry *ce,
 215                               struct unpack_trees_options *o)
 216{
 217        struct index_state *index = o->src_index;
 218        int len = ce_namelen(ce);
 219        int pos = index_name_pos(index, ce->name, len);
 220        if (pos < 0)
 221                pos = -1 - pos;
 222        return pos;
 223}
 224
 225/*
 226 * We call unpack_index_entry() with an unmerged cache entry
 227 * only in diff-index, and it wants a single callback.  Skip
 228 * the other unmerged entry with the same name.
 229 */
 230static void mark_ce_used_same_name(struct cache_entry *ce,
 231                                   struct unpack_trees_options *o)
 232{
 233        struct index_state *index = o->src_index;
 234        int len = ce_namelen(ce);
 235        int pos;
 236
 237        for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
 238                struct cache_entry *next = index->cache[pos];
 239                if (len != ce_namelen(next) ||
 240                    memcmp(ce->name, next->name, len))
 241                        break;
 242                mark_ce_used(next, o);
 243        }
 244}
 245
 246static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
 247{
 248        const struct index_state *index = o->src_index;
 249        int pos = o->cache_bottom;
 250
 251        while (pos < index->cache_nr) {
 252                struct cache_entry *ce = index->cache[pos];
 253                if (!(ce->ce_flags & CE_UNPACKED))
 254                        return ce;
 255                pos++;
 256        }
 257        return NULL;
 258}
 259
 260static void add_same_unmerged(struct cache_entry *ce,
 261                              struct unpack_trees_options *o)
 262{
 263        struct index_state *index = o->src_index;
 264        int len = ce_namelen(ce);
 265        int pos = index_name_pos(index, ce->name, len);
 266
 267        if (0 <= pos)
 268                die("programming error in a caller of mark_ce_used_same_name");
 269        for (pos = -pos - 1; pos < index->cache_nr; pos++) {
 270                struct cache_entry *next = index->cache[pos];
 271                if (len != ce_namelen(next) ||
 272                    memcmp(ce->name, next->name, len))
 273                        break;
 274                add_entry(o, next, 0, 0);
 275                mark_ce_used(next, o);
 276        }
 277}
 278
 279static int unpack_index_entry(struct cache_entry *ce,
 280                              struct unpack_trees_options *o)
 281{
 282        struct cache_entry *src[5] = { NULL };
 283        int ret;
 284
 285        src[0] = ce;
 286
 287        mark_ce_used(ce, o);
 288        if (ce_stage(ce)) {
 289                if (o->skip_unmerged) {
 290                        add_entry(o, ce, 0, 0);
 291                        return 0;
 292                }
 293        }
 294        ret = call_unpack_fn(src, o);
 295        if (ce_stage(ce))
 296                mark_ce_used_same_name(ce, o);
 297        return ret;
 298}
 299
 300static int find_cache_pos(struct traverse_info *, const struct name_entry *);
 301
 302static void restore_cache_bottom(struct traverse_info *info, int bottom)
 303{
 304        struct unpack_trees_options *o = info->data;
 305
 306        if (o->diff_index_cached)
 307                return;
 308        o->cache_bottom = bottom;
 309}
 310
 311static int switch_cache_bottom(struct traverse_info *info)
 312{
 313        struct unpack_trees_options *o = info->data;
 314        int ret, pos;
 315
 316        if (o->diff_index_cached)
 317                return 0;
 318        ret = o->cache_bottom;
 319        pos = find_cache_pos(info->prev, &info->name);
 320
 321        if (pos < -1)
 322                o->cache_bottom = -2 - pos;
 323        else if (pos < 0)
 324                o->cache_bottom = o->src_index->cache_nr;
 325        return ret;
 326}
 327
 328static int traverse_trees_recursive(int n, unsigned long dirmask, unsigned long df_conflicts, struct name_entry *names, struct traverse_info *info)
 329{
 330        int i, ret, bottom;
 331        struct tree_desc t[MAX_UNPACK_TREES];
 332        void *buf[MAX_UNPACK_TREES];
 333        struct traverse_info newinfo;
 334        struct name_entry *p;
 335
 336        p = names;
 337        while (!p->mode)
 338                p++;
 339
 340        newinfo = *info;
 341        newinfo.prev = info;
 342        newinfo.name = *p;
 343        newinfo.pathlen += tree_entry_len(p->path, p->sha1) + 1;
 344        newinfo.conflicts |= df_conflicts;
 345
 346        for (i = 0; i < n; i++, dirmask >>= 1) {
 347                const unsigned char *sha1 = NULL;
 348                if (dirmask & 1)
 349                        sha1 = names[i].sha1;
 350                buf[i] = fill_tree_descriptor(t+i, sha1);
 351        }
 352
 353        bottom = switch_cache_bottom(&newinfo);
 354        ret = traverse_trees(n, t, &newinfo);
 355        restore_cache_bottom(&newinfo, bottom);
 356
 357        for (i = 0; i < n; i++)
 358                free(buf[i]);
 359
 360        return ret;
 361}
 362
 363/*
 364 * Compare the traverse-path to the cache entry without actually
 365 * having to generate the textual representation of the traverse
 366 * path.
 367 *
 368 * NOTE! This *only* compares up to the size of the traverse path
 369 * itself - the caller needs to do the final check for the cache
 370 * entry having more data at the end!
 371 */
 372static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 373{
 374        int len, pathlen, ce_len;
 375        const char *ce_name;
 376
 377        if (info->prev) {
 378                int cmp = do_compare_entry(ce, info->prev, &info->name);
 379                if (cmp)
 380                        return cmp;
 381        }
 382        pathlen = info->pathlen;
 383        ce_len = ce_namelen(ce);
 384
 385        /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 386        if (ce_len < pathlen)
 387                return -1;
 388
 389        ce_len -= pathlen;
 390        ce_name = ce->name + pathlen;
 391
 392        len = tree_entry_len(n->path, n->sha1);
 393        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 394}
 395
 396static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 397{
 398        int cmp = do_compare_entry(ce, info, n);
 399        if (cmp)
 400                return cmp;
 401
 402        /*
 403         * Even if the beginning compared identically, the ce should
 404         * compare as bigger than a directory leading up to it!
 405         */
 406        return ce_namelen(ce) > traverse_path_len(info, n);
 407}
 408
 409static int ce_in_traverse_path(const struct cache_entry *ce,
 410                               const struct traverse_info *info)
 411{
 412        if (!info->prev)
 413                return 1;
 414        if (do_compare_entry(ce, info->prev, &info->name))
 415                return 0;
 416        /*
 417         * If ce (blob) is the same name as the path (which is a tree
 418         * we will be descending into), it won't be inside it.
 419         */
 420        return (info->pathlen < ce_namelen(ce));
 421}
 422
 423static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
 424{
 425        int len = traverse_path_len(info, n);
 426        struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
 427
 428        ce->ce_mode = create_ce_mode(n->mode);
 429        ce->ce_flags = create_ce_flags(len, stage);
 430        hashcpy(ce->sha1, n->sha1);
 431        make_traverse_path(ce->name, info, n);
 432
 433        return ce;
 434}
 435
 436static int unpack_nondirectories(int n, unsigned long mask,
 437                                 unsigned long dirmask,
 438                                 struct cache_entry **src,
 439                                 const struct name_entry *names,
 440                                 const struct traverse_info *info)
 441{
 442        int i;
 443        struct unpack_trees_options *o = info->data;
 444        unsigned long conflicts;
 445
 446        /* Do we have *only* directories? Nothing to do */
 447        if (mask == dirmask && !src[0])
 448                return 0;
 449
 450        conflicts = info->conflicts;
 451        if (o->merge)
 452                conflicts >>= 1;
 453        conflicts |= dirmask;
 454
 455        /*
 456         * Ok, we've filled in up to any potential index entry in src[0],
 457         * now do the rest.
 458         */
 459        for (i = 0; i < n; i++) {
 460                int stage;
 461                unsigned int bit = 1ul << i;
 462                if (conflicts & bit) {
 463                        src[i + o->merge] = o->df_conflict_entry;
 464                        continue;
 465                }
 466                if (!(mask & bit))
 467                        continue;
 468                if (!o->merge)
 469                        stage = 0;
 470                else if (i + 1 < o->head_idx)
 471                        stage = 1;
 472                else if (i + 1 > o->head_idx)
 473                        stage = 3;
 474                else
 475                        stage = 2;
 476                src[i + o->merge] = create_ce_entry(info, names + i, stage);
 477        }
 478
 479        if (o->merge)
 480                return call_unpack_fn(src, o);
 481
 482        for (i = 0; i < n; i++)
 483                if (src[i] && src[i] != o->df_conflict_entry)
 484                        add_entry(o, src[i], 0, 0);
 485        return 0;
 486}
 487
 488static int unpack_failed(struct unpack_trees_options *o, const char *message)
 489{
 490        discard_index(&o->result);
 491        if (!o->gently) {
 492                if (message)
 493                        return error("%s", message);
 494                return -1;
 495        }
 496        return -1;
 497}
 498
 499/* NEEDSWORK: give this a better name and share with tree-walk.c */
 500static int name_compare(const char *a, int a_len,
 501                        const char *b, int b_len)
 502{
 503        int len = (a_len < b_len) ? a_len : b_len;
 504        int cmp = memcmp(a, b, len);
 505        if (cmp)
 506                return cmp;
 507        return (a_len - b_len);
 508}
 509
 510/*
 511 * The tree traversal is looking at name p.  If we have a matching entry,
 512 * return it.  If name p is a directory in the index, do not return
 513 * anything, as we will want to match it when the traversal descends into
 514 * the directory.
 515 */
 516static int find_cache_pos(struct traverse_info *info,
 517                          const struct name_entry *p)
 518{
 519        int pos;
 520        struct unpack_trees_options *o = info->data;
 521        struct index_state *index = o->src_index;
 522        int pfxlen = info->pathlen;
 523        int p_len = tree_entry_len(p->path, p->sha1);
 524
 525        for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
 526                struct cache_entry *ce = index->cache[pos];
 527                const char *ce_name, *ce_slash;
 528                int cmp, ce_len;
 529
 530                if (ce->ce_flags & CE_UNPACKED) {
 531                        /*
 532                         * cache_bottom entry is already unpacked, so
 533                         * we can never match it; don't check it
 534                         * again.
 535                         */
 536                        if (pos == o->cache_bottom)
 537                                ++o->cache_bottom;
 538                        continue;
 539                }
 540                if (!ce_in_traverse_path(ce, info))
 541                        continue;
 542                ce_name = ce->name + pfxlen;
 543                ce_slash = strchr(ce_name, '/');
 544                if (ce_slash)
 545                        ce_len = ce_slash - ce_name;
 546                else
 547                        ce_len = ce_namelen(ce) - pfxlen;
 548                cmp = name_compare(p->path, p_len, ce_name, ce_len);
 549                /*
 550                 * Exact match; if we have a directory we need to
 551                 * delay returning it.
 552                 */
 553                if (!cmp)
 554                        return ce_slash ? -2 - pos : pos;
 555                if (0 < cmp)
 556                        continue; /* keep looking */
 557                /*
 558                 * ce_name sorts after p->path; could it be that we
 559                 * have files under p->path directory in the index?
 560                 * E.g.  ce_name == "t-i", and p->path == "t"; we may
 561                 * have "t/a" in the index.
 562                 */
 563                if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
 564                    ce_name[p_len] < '/')
 565                        continue; /* keep looking */
 566                break;
 567        }
 568        return -1;
 569}
 570
 571static struct cache_entry *find_cache_entry(struct traverse_info *info,
 572                                            const struct name_entry *p)
 573{
 574        int pos = find_cache_pos(info, p);
 575        struct unpack_trees_options *o = info->data;
 576
 577        if (0 <= pos)
 578                return o->src_index->cache[pos];
 579        else
 580                return NULL;
 581}
 582
 583static void debug_path(struct traverse_info *info)
 584{
 585        if (info->prev) {
 586                debug_path(info->prev);
 587                if (*info->prev->name.path)
 588                        putchar('/');
 589        }
 590        printf("%s", info->name.path);
 591}
 592
 593static void debug_name_entry(int i, struct name_entry *n)
 594{
 595        printf("ent#%d %06o %s\n", i,
 596               n->path ? n->mode : 0,
 597               n->path ? n->path : "(missing)");
 598}
 599
 600static void debug_unpack_callback(int n,
 601                                  unsigned long mask,
 602                                  unsigned long dirmask,
 603                                  struct name_entry *names,
 604                                  struct traverse_info *info)
 605{
 606        int i;
 607        printf("* unpack mask %lu, dirmask %lu, cnt %d ",
 608               mask, dirmask, n);
 609        debug_path(info);
 610        putchar('\n');
 611        for (i = 0; i < n; i++)
 612                debug_name_entry(i, names + i);
 613}
 614
 615static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
 616{
 617        struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 618        struct unpack_trees_options *o = info->data;
 619        const struct name_entry *p = names;
 620
 621        /* Find first entry with a real name (we could use "mask" too) */
 622        while (!p->mode)
 623                p++;
 624
 625        if (o->debug_unpack)
 626                debug_unpack_callback(n, mask, dirmask, names, info);
 627
 628        /* Are we supposed to look at the index too? */
 629        if (o->merge) {
 630                while (1) {
 631                        int cmp;
 632                        struct cache_entry *ce;
 633
 634                        if (o->diff_index_cached)
 635                                ce = next_cache_entry(o);
 636                        else
 637                                ce = find_cache_entry(info, p);
 638
 639                        if (!ce)
 640                                break;
 641                        cmp = compare_entry(ce, info, p);
 642                        if (cmp < 0) {
 643                                if (unpack_index_entry(ce, o) < 0)
 644                                        return unpack_failed(o, NULL);
 645                                continue;
 646                        }
 647                        if (!cmp) {
 648                                if (ce_stage(ce)) {
 649                                        /*
 650                                         * If we skip unmerged index
 651                                         * entries, we'll skip this
 652                                         * entry *and* the tree
 653                                         * entries associated with it!
 654                                         */
 655                                        if (o->skip_unmerged) {
 656                                                add_same_unmerged(ce, o);
 657                                                return mask;
 658                                        }
 659                                }
 660                                src[0] = ce;
 661                        }
 662                        break;
 663                }
 664        }
 665
 666        if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
 667                return -1;
 668
 669        if (src[0]) {
 670                if (ce_stage(src[0]))
 671                        mark_ce_used_same_name(src[0], o);
 672                else
 673                        mark_ce_used(src[0], o);
 674        }
 675
 676        /* Now handle any directories.. */
 677        if (dirmask) {
 678                unsigned long conflicts = mask & ~dirmask;
 679                if (o->merge) {
 680                        conflicts <<= 1;
 681                        if (src[0])
 682                                conflicts |= 1;
 683                }
 684
 685                /* special case: "diff-index --cached" looking at a tree */
 686                if (o->diff_index_cached &&
 687                    n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
 688                        int matches;
 689                        matches = cache_tree_matches_traversal(o->src_index->cache_tree,
 690                                                               names, info);
 691                        /*
 692                         * Everything under the name matches; skip the
 693                         * entire hierarchy.  diff_index_cached codepath
 694                         * special cases D/F conflicts in such a way that
 695                         * it does not do any look-ahead, so this is safe.
 696                         */
 697                        if (matches) {
 698                                o->cache_bottom += matches;
 699                                return mask;
 700                        }
 701                }
 702
 703                if (traverse_trees_recursive(n, dirmask, conflicts,
 704                                             names, info) < 0)
 705                        return -1;
 706                return mask;
 707        }
 708
 709        return mask;
 710}
 711
 712/*
 713 * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
 714 * resulting index, -2 on failure to reflect the changes to the work tree.
 715 */
 716int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
 717{
 718        int i, ret;
 719        static struct cache_entry *dfc;
 720        struct exclude_list el;
 721
 722        if (len > MAX_UNPACK_TREES)
 723                die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
 724        memset(&state, 0, sizeof(state));
 725        state.base_dir = "";
 726        state.force = 1;
 727        state.quiet = 1;
 728        state.refresh_cache = 1;
 729
 730        memset(&el, 0, sizeof(el));
 731        if (!core_apply_sparse_checkout || !o->update)
 732                o->skip_sparse_checkout = 1;
 733        if (!o->skip_sparse_checkout) {
 734                if (add_excludes_from_file_to_list(git_path("info/sparse-checkout"), "", 0, NULL, &el, 0) < 0)
 735                        o->skip_sparse_checkout = 1;
 736                else
 737                        o->el = &el;
 738        }
 739
 740        memset(&o->result, 0, sizeof(o->result));
 741        o->result.initialized = 1;
 742        o->result.timestamp.sec = o->src_index->timestamp.sec;
 743        o->result.timestamp.nsec = o->src_index->timestamp.nsec;
 744        o->merge_size = len;
 745        mark_all_ce_unused(o->src_index);
 746
 747        if (!dfc)
 748                dfc = xcalloc(1, cache_entry_size(0));
 749        o->df_conflict_entry = dfc;
 750
 751        if (len) {
 752                const char *prefix = o->prefix ? o->prefix : "";
 753                struct traverse_info info;
 754
 755                setup_traverse_info(&info, prefix);
 756                info.fn = unpack_callback;
 757                info.data = o;
 758
 759                if (o->prefix) {
 760                        /*
 761                         * Unpack existing index entries that sort before the
 762                         * prefix the tree is spliced into.  Note that o->merge
 763                         * is always true in this case.
 764                         */
 765                        while (1) {
 766                                struct cache_entry *ce = next_cache_entry(o);
 767                                if (!ce)
 768                                        break;
 769                                if (ce_in_traverse_path(ce, &info))
 770                                        break;
 771                                if (unpack_index_entry(ce, o) < 0)
 772                                        goto return_failed;
 773                        }
 774                }
 775
 776                if (traverse_trees(len, t, &info) < 0)
 777                        goto return_failed;
 778        }
 779
 780        /* Any left-over entries in the index? */
 781        if (o->merge) {
 782                while (1) {
 783                        struct cache_entry *ce = next_cache_entry(o);
 784                        if (!ce)
 785                                break;
 786                        if (unpack_index_entry(ce, o) < 0)
 787                                goto return_failed;
 788                }
 789        }
 790        mark_all_ce_unused(o->src_index);
 791
 792        if (o->trivial_merges_only && o->nontrivial_merge) {
 793                ret = unpack_failed(o, "Merge requires file-level merging");
 794                goto done;
 795        }
 796
 797        if (!o->skip_sparse_checkout) {
 798                int empty_worktree = 1;
 799                for (i = 0;i < o->result.cache_nr;i++) {
 800                        struct cache_entry *ce = o->result.cache[i];
 801
 802                        if (apply_sparse_checkout(ce, o)) {
 803                                ret = -1;
 804                                goto done;
 805                        }
 806                        /*
 807                         * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
 808                         * area as a result of ce_skip_worktree() shortcuts in
 809                         * verify_absent() and verify_uptodate(). Clear them.
 810                         */
 811                        if (ce_skip_worktree(ce))
 812                                ce->ce_flags &= ~(CE_UPDATE | CE_REMOVE);
 813                        else
 814                                empty_worktree = 0;
 815
 816                }
 817                if (o->result.cache_nr && empty_worktree) {
 818                        ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
 819                        goto done;
 820                }
 821        }
 822
 823        o->src_index = NULL;
 824        ret = check_updates(o) ? (-2) : 0;
 825        if (o->dst_index)
 826                *o->dst_index = o->result;
 827
 828done:
 829        for (i = 0;i < el.nr;i++)
 830                free(el.excludes[i]);
 831        if (el.excludes)
 832                free(el.excludes);
 833
 834        return ret;
 835
 836return_failed:
 837        mark_all_ce_unused(o->src_index);
 838        ret = unpack_failed(o, NULL);
 839        goto done;
 840}
 841
 842/* Here come the merge functions */
 843
 844static int reject_merge(struct cache_entry *ce, struct unpack_trees_options *o)
 845{
 846        return error(ERRORMSG(o, would_overwrite), ce->name);
 847}
 848
 849static int same(struct cache_entry *a, struct cache_entry *b)
 850{
 851        if (!!a != !!b)
 852                return 0;
 853        if (!a && !b)
 854                return 1;
 855        if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
 856                return 0;
 857        return a->ce_mode == b->ce_mode &&
 858               !hashcmp(a->sha1, b->sha1);
 859}
 860
 861
 862/*
 863 * When a CE gets turned into an unmerged entry, we
 864 * want it to be up-to-date
 865 */
 866static int verify_uptodate_1(struct cache_entry *ce,
 867                                   struct unpack_trees_options *o,
 868                                   const char *error_msg)
 869{
 870        struct stat st;
 871
 872        if (o->index_only || (!((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce)) && (o->reset || ce_uptodate(ce))))
 873                return 0;
 874
 875        if (!lstat(ce->name, &st)) {
 876                unsigned changed = ie_match_stat(o->src_index, ce, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
 877                if (!changed)
 878                        return 0;
 879                /*
 880                 * NEEDSWORK: the current default policy is to allow
 881                 * submodule to be out of sync wrt the supermodule
 882                 * index.  This needs to be tightened later for
 883                 * submodules that are marked to be automatically
 884                 * checked out.
 885                 */
 886                if (S_ISGITLINK(ce->ce_mode))
 887                        return 0;
 888                errno = 0;
 889        }
 890        if (errno == ENOENT)
 891                return 0;
 892        return o->gently ? -1 :
 893                error(error_msg, ce->name);
 894}
 895
 896static int verify_uptodate(struct cache_entry *ce,
 897                           struct unpack_trees_options *o)
 898{
 899        if (!o->skip_sparse_checkout && will_have_skip_worktree(ce, o))
 900                return 0;
 901        return verify_uptodate_1(ce, o, ERRORMSG(o, not_uptodate_file));
 902}
 903
 904static int verify_uptodate_sparse(struct cache_entry *ce,
 905                                  struct unpack_trees_options *o)
 906{
 907        return verify_uptodate_1(ce, o, ERRORMSG(o, sparse_not_uptodate_file));
 908}
 909
 910static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
 911{
 912        if (ce)
 913                cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
 914}
 915
 916/*
 917 * Check that checking out ce->sha1 in subdir ce->name is not
 918 * going to overwrite any working files.
 919 *
 920 * Currently, git does not checkout subprojects during a superproject
 921 * checkout, so it is not going to overwrite anything.
 922 */
 923static int verify_clean_submodule(struct cache_entry *ce, const char *action,
 924                                      struct unpack_trees_options *o)
 925{
 926        return 0;
 927}
 928
 929static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
 930                                      struct unpack_trees_options *o)
 931{
 932        /*
 933         * we are about to extract "ce->name"; we would not want to lose
 934         * anything in the existing directory there.
 935         */
 936        int namelen;
 937        int i;
 938        struct dir_struct d;
 939        char *pathbuf;
 940        int cnt = 0;
 941        unsigned char sha1[20];
 942
 943        if (S_ISGITLINK(ce->ce_mode) &&
 944            resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
 945                /* If we are not going to update the submodule, then
 946                 * we don't care.
 947                 */
 948                if (!hashcmp(sha1, ce->sha1))
 949                        return 0;
 950                return verify_clean_submodule(ce, action, o);
 951        }
 952
 953        /*
 954         * First let's make sure we do not have a local modification
 955         * in that directory.
 956         */
 957        namelen = strlen(ce->name);
 958        for (i = locate_in_src_index(ce, o);
 959             i < o->src_index->cache_nr;
 960             i++) {
 961                struct cache_entry *ce2 = o->src_index->cache[i];
 962                int len = ce_namelen(ce2);
 963                if (len < namelen ||
 964                    strncmp(ce->name, ce2->name, namelen) ||
 965                    ce2->name[namelen] != '/')
 966                        break;
 967                /*
 968                 * ce2->name is an entry in the subdirectory to be
 969                 * removed.
 970                 */
 971                if (!ce_stage(ce2)) {
 972                        if (verify_uptodate(ce2, o))
 973                                return -1;
 974                        add_entry(o, ce2, CE_REMOVE, 0);
 975                        mark_ce_used(ce2, o);
 976                }
 977                cnt++;
 978        }
 979
 980        /*
 981         * Then we need to make sure that we do not lose a locally
 982         * present file that is not ignored.
 983         */
 984        pathbuf = xmalloc(namelen + 2);
 985        memcpy(pathbuf, ce->name, namelen);
 986        strcpy(pathbuf+namelen, "/");
 987
 988        memset(&d, 0, sizeof(d));
 989        if (o->dir)
 990                d.exclude_per_dir = o->dir->exclude_per_dir;
 991        i = read_directory(&d, pathbuf, namelen+1, NULL);
 992        if (i)
 993                return o->gently ? -1 :
 994                        error(ERRORMSG(o, not_uptodate_dir), ce->name);
 995        free(pathbuf);
 996        return cnt;
 997}
 998
 999/*
1000 * This gets called when there was no index entry for the tree entry 'dst',
1001 * but we found a file in the working tree that 'lstat()' said was fine,
1002 * and we're on a case-insensitive filesystem.
1003 *
1004 * See if we can find a case-insensitive match in the index that also
1005 * matches the stat information, and assume it's that other file!
1006 */
1007static int icase_exists(struct unpack_trees_options *o, struct cache_entry *dst, struct stat *st)
1008{
1009        struct cache_entry *src;
1010
1011        src = index_name_exists(o->src_index, dst->name, ce_namelen(dst), 1);
1012        return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1013}
1014
1015/*
1016 * We do not want to remove or overwrite a working tree file that
1017 * is not tracked, unless it is ignored.
1018 */
1019static int verify_absent_1(struct cache_entry *ce, const char *action,
1020                                 struct unpack_trees_options *o,
1021                                 const char *error_msg)
1022{
1023        struct stat st;
1024
1025        if (o->index_only || o->reset || !o->update)
1026                return 0;
1027
1028        if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
1029                return 0;
1030
1031        if (!lstat(ce->name, &st)) {
1032                int dtype = ce_to_dtype(ce);
1033                struct cache_entry *result;
1034
1035                /*
1036                 * It may be that the 'lstat()' succeeded even though
1037                 * target 'ce' was absent, because there is an old
1038                 * entry that is different only in case..
1039                 *
1040                 * Ignore that lstat() if it matches.
1041                 */
1042                if (ignore_case && icase_exists(o, ce, &st))
1043                        return 0;
1044
1045                if (o->dir && excluded(o->dir, ce->name, &dtype))
1046                        /*
1047                         * ce->name is explicitly excluded, so it is Ok to
1048                         * overwrite it.
1049                         */
1050                        return 0;
1051                if (S_ISDIR(st.st_mode)) {
1052                        /*
1053                         * We are checking out path "foo" and
1054                         * found "foo/." in the working tree.
1055                         * This is tricky -- if we have modified
1056                         * files that are in "foo/" we would lose
1057                         * them.
1058                         */
1059                        if (verify_clean_subdirectory(ce, action, o) < 0)
1060                                return -1;
1061                        return 0;
1062                }
1063
1064                /*
1065                 * The previous round may already have decided to
1066                 * delete this path, which is in a subdirectory that
1067                 * is being replaced with a blob.
1068                 */
1069                result = index_name_exists(&o->result, ce->name, ce_namelen(ce), 0);
1070                if (result) {
1071                        if (result->ce_flags & CE_REMOVE)
1072                                return 0;
1073                }
1074
1075                return o->gently ? -1 :
1076                        error(ERRORMSG(o, would_lose_untracked), ce->name, action);
1077        }
1078        return 0;
1079}
1080static int verify_absent(struct cache_entry *ce, const char *action,
1081                         struct unpack_trees_options *o)
1082{
1083        if (!o->skip_sparse_checkout && will_have_skip_worktree(ce, o))
1084                return 0;
1085        return verify_absent_1(ce, action, o, ERRORMSG(o, would_lose_untracked));
1086}
1087
1088static int verify_absent_sparse(struct cache_entry *ce, const char *action,
1089                         struct unpack_trees_options *o)
1090{
1091        return verify_absent_1(ce, action, o, ERRORMSG(o, would_lose_orphaned));
1092}
1093
1094static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
1095                struct unpack_trees_options *o)
1096{
1097        int update = CE_UPDATE;
1098
1099        if (!old) {
1100                if (verify_absent(merge, "overwritten", o))
1101                        return -1;
1102                invalidate_ce_path(merge, o);
1103        } else if (!(old->ce_flags & CE_CONFLICTED)) {
1104                /*
1105                 * See if we can re-use the old CE directly?
1106                 * That way we get the uptodate stat info.
1107                 *
1108                 * This also removes the UPDATE flag on a match; otherwise
1109                 * we will end up overwriting local changes in the work tree.
1110                 */
1111                if (same(old, merge)) {
1112                        copy_cache_entry(merge, old);
1113                        update = 0;
1114                } else {
1115                        if (verify_uptodate(old, o))
1116                                return -1;
1117                        if (ce_skip_worktree(old))
1118                                update |= CE_SKIP_WORKTREE;
1119                        invalidate_ce_path(old, o);
1120                }
1121        } else {
1122                /*
1123                 * Previously unmerged entry left as an existence
1124                 * marker by read_index_unmerged();
1125                 */
1126                invalidate_ce_path(old, o);
1127        }
1128
1129        add_entry(o, merge, update, CE_STAGEMASK);
1130        return 1;
1131}
1132
1133static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
1134                struct unpack_trees_options *o)
1135{
1136        /* Did it exist in the index? */
1137        if (!old) {
1138                if (verify_absent(ce, "removed", o))
1139                        return -1;
1140                return 0;
1141        }
1142        if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1143                return -1;
1144        add_entry(o, ce, CE_REMOVE, 0);
1145        invalidate_ce_path(ce, o);
1146        return 1;
1147}
1148
1149static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
1150{
1151        add_entry(o, ce, 0, 0);
1152        return 1;
1153}
1154
1155#if DBRT_DEBUG
1156static void show_stage_entry(FILE *o,
1157                             const char *label, const struct cache_entry *ce)
1158{
1159        if (!ce)
1160                fprintf(o, "%s (missing)\n", label);
1161        else
1162                fprintf(o, "%s%06o %s %d\t%s\n",
1163                        label,
1164                        ce->ce_mode,
1165                        sha1_to_hex(ce->sha1),
1166                        ce_stage(ce),
1167                        ce->name);
1168}
1169#endif
1170
1171int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
1172{
1173        struct cache_entry *index;
1174        struct cache_entry *head;
1175        struct cache_entry *remote = stages[o->head_idx + 1];
1176        int count;
1177        int head_match = 0;
1178        int remote_match = 0;
1179
1180        int df_conflict_head = 0;
1181        int df_conflict_remote = 0;
1182
1183        int any_anc_missing = 0;
1184        int no_anc_exists = 1;
1185        int i;
1186
1187        for (i = 1; i < o->head_idx; i++) {
1188                if (!stages[i] || stages[i] == o->df_conflict_entry)
1189                        any_anc_missing = 1;
1190                else
1191                        no_anc_exists = 0;
1192        }
1193
1194        index = stages[0];
1195        head = stages[o->head_idx];
1196
1197        if (head == o->df_conflict_entry) {
1198                df_conflict_head = 1;
1199                head = NULL;
1200        }
1201
1202        if (remote == o->df_conflict_entry) {
1203                df_conflict_remote = 1;
1204                remote = NULL;
1205        }
1206
1207        /*
1208         * First, if there's a #16 situation, note that to prevent #13
1209         * and #14.
1210         */
1211        if (!same(remote, head)) {
1212                for (i = 1; i < o->head_idx; i++) {
1213                        if (same(stages[i], head)) {
1214                                head_match = i;
1215                        }
1216                        if (same(stages[i], remote)) {
1217                                remote_match = i;
1218                        }
1219                }
1220        }
1221
1222        /*
1223         * We start with cases where the index is allowed to match
1224         * something other than the head: #14(ALT) and #2ALT, where it
1225         * is permitted to match the result instead.
1226         */
1227        /* #14, #14ALT, #2ALT */
1228        if (remote && !df_conflict_head && head_match && !remote_match) {
1229                if (index && !same(index, remote) && !same(index, head))
1230                        return o->gently ? -1 : reject_merge(index, o);
1231                return merged_entry(remote, index, o);
1232        }
1233        /*
1234         * If we have an entry in the index cache, then we want to
1235         * make sure that it matches head.
1236         */
1237        if (index && !same(index, head))
1238                return o->gently ? -1 : reject_merge(index, o);
1239
1240        if (head) {
1241                /* #5ALT, #15 */
1242                if (same(head, remote))
1243                        return merged_entry(head, index, o);
1244                /* #13, #3ALT */
1245                if (!df_conflict_remote && remote_match && !head_match)
1246                        return merged_entry(head, index, o);
1247        }
1248
1249        /* #1 */
1250        if (!head && !remote && any_anc_missing)
1251                return 0;
1252
1253        /*
1254         * Under the "aggressive" rule, we resolve mostly trivial
1255         * cases that we historically had git-merge-one-file resolve.
1256         */
1257        if (o->aggressive) {
1258                int head_deleted = !head;
1259                int remote_deleted = !remote;
1260                struct cache_entry *ce = NULL;
1261
1262                if (index)
1263                        ce = index;
1264                else if (head)
1265                        ce = head;
1266                else if (remote)
1267                        ce = remote;
1268                else {
1269                        for (i = 1; i < o->head_idx; i++) {
1270                                if (stages[i] && stages[i] != o->df_conflict_entry) {
1271                                        ce = stages[i];
1272                                        break;
1273                                }
1274                        }
1275                }
1276
1277                /*
1278                 * Deleted in both.
1279                 * Deleted in one and unchanged in the other.
1280                 */
1281                if ((head_deleted && remote_deleted) ||
1282                    (head_deleted && remote && remote_match) ||
1283                    (remote_deleted && head && head_match)) {
1284                        if (index)
1285                                return deleted_entry(index, index, o);
1286                        if (ce && !head_deleted) {
1287                                if (verify_absent(ce, "removed", o))
1288                                        return -1;
1289                        }
1290                        return 0;
1291                }
1292                /*
1293                 * Added in both, identically.
1294                 */
1295                if (no_anc_exists && head && remote && same(head, remote))
1296                        return merged_entry(head, index, o);
1297
1298        }
1299
1300        /* Below are "no merge" cases, which require that the index be
1301         * up-to-date to avoid the files getting overwritten with
1302         * conflict resolution files.
1303         */
1304        if (index) {
1305                if (verify_uptodate(index, o))
1306                        return -1;
1307        }
1308
1309        o->nontrivial_merge = 1;
1310
1311        /* #2, #3, #4, #6, #7, #9, #10, #11. */
1312        count = 0;
1313        if (!head_match || !remote_match) {
1314                for (i = 1; i < o->head_idx; i++) {
1315                        if (stages[i] && stages[i] != o->df_conflict_entry) {
1316                                keep_entry(stages[i], o);
1317                                count++;
1318                                break;
1319                        }
1320                }
1321        }
1322#if DBRT_DEBUG
1323        else {
1324                fprintf(stderr, "read-tree: warning #16 detected\n");
1325                show_stage_entry(stderr, "head   ", stages[head_match]);
1326                show_stage_entry(stderr, "remote ", stages[remote_match]);
1327        }
1328#endif
1329        if (head) { count += keep_entry(head, o); }
1330        if (remote) { count += keep_entry(remote, o); }
1331        return count;
1332}
1333
1334/*
1335 * Two-way merge.
1336 *
1337 * The rule is to "carry forward" what is in the index without losing
1338 * information across a "fast-forward", favoring a successful merge
1339 * over a merge failure when it makes sense.  For details of the
1340 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
1341 *
1342 */
1343int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1344{
1345        struct cache_entry *current = src[0];
1346        struct cache_entry *oldtree = src[1];
1347        struct cache_entry *newtree = src[2];
1348
1349        if (o->merge_size != 2)
1350                return error("Cannot do a twoway merge of %d trees",
1351                             o->merge_size);
1352
1353        if (oldtree == o->df_conflict_entry)
1354                oldtree = NULL;
1355        if (newtree == o->df_conflict_entry)
1356                newtree = NULL;
1357
1358        if (current) {
1359                if ((!oldtree && !newtree) || /* 4 and 5 */
1360                    (!oldtree && newtree &&
1361                     same(current, newtree)) || /* 6 and 7 */
1362                    (oldtree && newtree &&
1363                     same(oldtree, newtree)) || /* 14 and 15 */
1364                    (oldtree && newtree &&
1365                     !same(oldtree, newtree) && /* 18 and 19 */
1366                     same(current, newtree))) {
1367                        return keep_entry(current, o);
1368                }
1369                else if (oldtree && !newtree && same(current, oldtree)) {
1370                        /* 10 or 11 */
1371                        return deleted_entry(oldtree, current, o);
1372                }
1373                else if (oldtree && newtree &&
1374                         same(current, oldtree) && !same(current, newtree)) {
1375                        /* 20 or 21 */
1376                        return merged_entry(newtree, current, o);
1377                }
1378                else {
1379                        /* all other failures */
1380                        if (oldtree)
1381                                return o->gently ? -1 : reject_merge(oldtree, o);
1382                        if (current)
1383                                return o->gently ? -1 : reject_merge(current, o);
1384                        if (newtree)
1385                                return o->gently ? -1 : reject_merge(newtree, o);
1386                        return -1;
1387                }
1388        }
1389        else if (newtree) {
1390                if (oldtree && !o->initial_checkout) {
1391                        /*
1392                         * deletion of the path was staged;
1393                         */
1394                        if (same(oldtree, newtree))
1395                                return 1;
1396                        return reject_merge(oldtree, o);
1397                }
1398                return merged_entry(newtree, current, o);
1399        }
1400        return deleted_entry(oldtree, current, o);
1401}
1402
1403/*
1404 * Bind merge.
1405 *
1406 * Keep the index entries at stage0, collapse stage1 but make sure
1407 * stage0 does not have anything there.
1408 */
1409int bind_merge(struct cache_entry **src,
1410                struct unpack_trees_options *o)
1411{
1412        struct cache_entry *old = src[0];
1413        struct cache_entry *a = src[1];
1414
1415        if (o->merge_size != 1)
1416                return error("Cannot do a bind merge of %d trees\n",
1417                             o->merge_size);
1418        if (a && old)
1419                return o->gently ? -1 :
1420                        error(ERRORMSG(o, bind_overlap), a->name, old->name);
1421        if (!a)
1422                return keep_entry(old, o);
1423        else
1424                return merged_entry(a, NULL, o);
1425}
1426
1427/*
1428 * One-way merge.
1429 *
1430 * The rule is:
1431 * - take the stat information from stage0, take the data from stage1
1432 */
1433int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1434{
1435        struct cache_entry *old = src[0];
1436        struct cache_entry *a = src[1];
1437
1438        if (o->merge_size != 1)
1439                return error("Cannot do a oneway merge of %d trees",
1440                             o->merge_size);
1441
1442        if (!a || a == o->df_conflict_entry)
1443                return deleted_entry(old, old, o);
1444
1445        if (old && same(old, a)) {
1446                int update = 0;
1447                if (o->reset && !ce_uptodate(old) && !ce_skip_worktree(old)) {
1448                        struct stat st;
1449                        if (lstat(old->name, &st) ||
1450                            ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
1451                                update |= CE_UPDATE;
1452                }
1453                add_entry(o, old, update, 0);
1454                return 0;
1455        }
1456        return merged_entry(a, old, o);
1457}