273b5da0a256337c3d3973b475e7cfa567cee35a
   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
  11/*
  12 * Error messages expected by scripts out of plumbing commands such as
  13 * read-tree.  Non-scripted Porcelain is not required to use these messages
  14 * and in fact are encouraged to reword them to better suit their particular
  15 * situation better.  See how "git checkout" replaces not_uptodate_file to
  16 * explain why it does not allow switching between branches when you have
  17 * local changes, for example.
  18 */
  19static struct unpack_trees_error_msgs unpack_plumbing_errors = {
  20        /* would_overwrite */
  21        "Entry '%s' would be overwritten by merge. Cannot merge.",
  22
  23        /* not_uptodate_file */
  24        "Entry '%s' not uptodate. Cannot merge.",
  25
  26        /* not_uptodate_dir */
  27        "Updating '%s' would lose untracked files in it",
  28
  29        /* would_lose_untracked */
  30        "Untracked working tree file '%s' would be %s by merge.",
  31
  32        /* bind_overlap */
  33        "Entry '%s' overlaps with '%s'.  Cannot bind.",
  34};
  35
  36#define ERRORMSG(o,fld) \
  37        ( ((o) && (o)->msgs.fld) \
  38        ? ((o)->msgs.fld) \
  39        : (unpack_plumbing_errors.fld) )
  40
  41static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
  42        unsigned int set, unsigned int clear)
  43{
  44        unsigned int size = ce_size(ce);
  45        struct cache_entry *new = xmalloc(size);
  46
  47        clear |= CE_HASHED | CE_UNHASHED;
  48
  49        memcpy(new, ce, size);
  50        new->next = NULL;
  51        new->ce_flags = (new->ce_flags & ~clear) | set;
  52        add_index_entry(&o->result, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE|ADD_CACHE_SKIP_DFCHECK);
  53}
  54
  55/*
  56 * Unlink the last component and schedule the leading directories for
  57 * removal, such that empty directories get removed.
  58 */
  59static void unlink_entry(struct cache_entry *ce)
  60{
  61        if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
  62                return;
  63        if (unlink(ce->name))
  64                return;
  65        schedule_dir_for_removal(ce->name, ce_namelen(ce));
  66}
  67
  68static struct checkout state;
  69static int check_updates(struct unpack_trees_options *o)
  70{
  71        unsigned cnt = 0, total = 0;
  72        struct progress *progress = NULL;
  73        struct index_state *index = &o->result;
  74        int i;
  75        int errs = 0;
  76
  77        if (o->update && o->verbose_update) {
  78                for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
  79                        struct cache_entry *ce = index->cache[cnt];
  80                        if (ce->ce_flags & (CE_UPDATE | CE_REMOVE))
  81                                total++;
  82                }
  83
  84                progress = start_progress_delay("Checking out files",
  85                                                total, 50, 1);
  86                cnt = 0;
  87        }
  88
  89        for (i = 0; i < index->cache_nr; i++) {
  90                struct cache_entry *ce = index->cache[i];
  91
  92                if (ce->ce_flags & CE_REMOVE) {
  93                        display_progress(progress, ++cnt);
  94                        if (o->update)
  95                                unlink_entry(ce);
  96                }
  97        }
  98        remove_marked_cache_entries(&o->result);
  99        remove_scheduled_dirs();
 100
 101        for (i = 0; i < index->cache_nr; i++) {
 102                struct cache_entry *ce = index->cache[i];
 103
 104                if (ce->ce_flags & CE_UPDATE) {
 105                        display_progress(progress, ++cnt);
 106                        ce->ce_flags &= ~CE_UPDATE;
 107                        if (o->update) {
 108                                errs |= checkout_entry(ce, &state, NULL);
 109                        }
 110                }
 111        }
 112        stop_progress(&progress);
 113        return errs != 0;
 114}
 115
 116static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
 117{
 118        int ret = o->fn(src, o);
 119        if (ret > 0)
 120                ret = 0;
 121        return ret;
 122}
 123
 124static int unpack_index_entry(struct cache_entry *ce, struct unpack_trees_options *o)
 125{
 126        struct cache_entry *src[5] = { ce, };
 127
 128        o->pos++;
 129        if (ce_stage(ce)) {
 130                if (o->skip_unmerged) {
 131                        add_entry(o, ce, 0, 0);
 132                        return 0;
 133                }
 134        }
 135        return call_unpack_fn(src, o);
 136}
 137
 138int traverse_trees_recursive(int n, unsigned long dirmask, unsigned long df_conflicts, struct name_entry *names, struct traverse_info *info)
 139{
 140        int i;
 141        struct tree_desc t[MAX_UNPACK_TREES];
 142        struct traverse_info newinfo;
 143        struct name_entry *p;
 144
 145        p = names;
 146        while (!p->mode)
 147                p++;
 148
 149        newinfo = *info;
 150        newinfo.prev = info;
 151        newinfo.name = *p;
 152        newinfo.pathlen += tree_entry_len(p->path, p->sha1) + 1;
 153        newinfo.conflicts |= df_conflicts;
 154
 155        for (i = 0; i < n; i++, dirmask >>= 1) {
 156                const unsigned char *sha1 = NULL;
 157                if (dirmask & 1)
 158                        sha1 = names[i].sha1;
 159                fill_tree_descriptor(t+i, sha1);
 160        }
 161        return traverse_trees(n, t, &newinfo);
 162}
 163
 164/*
 165 * Compare the traverse-path to the cache entry without actually
 166 * having to generate the textual representation of the traverse
 167 * path.
 168 *
 169 * NOTE! This *only* compares up to the size of the traverse path
 170 * itself - the caller needs to do the final check for the cache
 171 * entry having more data at the end!
 172 */
 173static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 174{
 175        int len, pathlen, ce_len;
 176        const char *ce_name;
 177
 178        if (info->prev) {
 179                int cmp = do_compare_entry(ce, info->prev, &info->name);
 180                if (cmp)
 181                        return cmp;
 182        }
 183        pathlen = info->pathlen;
 184        ce_len = ce_namelen(ce);
 185
 186        /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 187        if (ce_len < pathlen)
 188                return -1;
 189
 190        ce_len -= pathlen;
 191        ce_name = ce->name + pathlen;
 192
 193        len = tree_entry_len(n->path, n->sha1);
 194        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 195}
 196
 197static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 198{
 199        int cmp = do_compare_entry(ce, info, n);
 200        if (cmp)
 201                return cmp;
 202
 203        /*
 204         * Even if the beginning compared identically, the ce should
 205         * compare as bigger than a directory leading up to it!
 206         */
 207        return ce_namelen(ce) > traverse_path_len(info, n);
 208}
 209
 210static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
 211{
 212        int len = traverse_path_len(info, n);
 213        struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
 214
 215        ce->ce_mode = create_ce_mode(n->mode);
 216        ce->ce_flags = create_ce_flags(len, stage);
 217        hashcpy(ce->sha1, n->sha1);
 218        make_traverse_path(ce->name, info, n);
 219
 220        return ce;
 221}
 222
 223static int unpack_nondirectories(int n, unsigned long mask,
 224                                 unsigned long dirmask,
 225                                 struct cache_entry **src,
 226                                 const struct name_entry *names,
 227                                 const struct traverse_info *info)
 228{
 229        int i;
 230        struct unpack_trees_options *o = info->data;
 231        unsigned long conflicts;
 232
 233        /* Do we have *only* directories? Nothing to do */
 234        if (mask == dirmask && !src[0])
 235                return 0;
 236
 237        conflicts = info->conflicts;
 238        if (o->merge)
 239                conflicts >>= 1;
 240        conflicts |= dirmask;
 241
 242        /*
 243         * Ok, we've filled in up to any potential index entry in src[0],
 244         * now do the rest.
 245         */
 246        for (i = 0; i < n; i++) {
 247                int stage;
 248                unsigned int bit = 1ul << i;
 249                if (conflicts & bit) {
 250                        src[i + o->merge] = o->df_conflict_entry;
 251                        continue;
 252                }
 253                if (!(mask & bit))
 254                        continue;
 255                if (!o->merge)
 256                        stage = 0;
 257                else if (i + 1 < o->head_idx)
 258                        stage = 1;
 259                else if (i + 1 > o->head_idx)
 260                        stage = 3;
 261                else
 262                        stage = 2;
 263                src[i + o->merge] = create_ce_entry(info, names + i, stage);
 264        }
 265
 266        if (o->merge)
 267                return call_unpack_fn(src, o);
 268
 269        n += o->merge;
 270        for (i = 0; i < n; i++)
 271                add_entry(o, src[i], 0, 0);
 272        return 0;
 273}
 274
 275static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
 276{
 277        struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 278        struct unpack_trees_options *o = info->data;
 279        const struct name_entry *p = names;
 280
 281        /* Find first entry with a real name (we could use "mask" too) */
 282        while (!p->mode)
 283                p++;
 284
 285        /* Are we supposed to look at the index too? */
 286        if (o->merge) {
 287                while (o->pos < o->src_index->cache_nr) {
 288                        struct cache_entry *ce = o->src_index->cache[o->pos];
 289                        int cmp = compare_entry(ce, info, p);
 290                        if (cmp < 0) {
 291                                if (unpack_index_entry(ce, o) < 0)
 292                                        return -1;
 293                                continue;
 294                        }
 295                        if (!cmp) {
 296                                o->pos++;
 297                                if (ce_stage(ce)) {
 298                                        /*
 299                                         * If we skip unmerged index entries, we'll skip this
 300                                         * entry *and* the tree entries associated with it!
 301                                         */
 302                                        if (o->skip_unmerged) {
 303                                                add_entry(o, ce, 0, 0);
 304                                                return mask;
 305                                        }
 306                                }
 307                                src[0] = ce;
 308                        }
 309                        break;
 310                }
 311        }
 312
 313        if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
 314                return -1;
 315
 316        /* Now handle any directories.. */
 317        if (dirmask) {
 318                unsigned long conflicts = mask & ~dirmask;
 319                if (o->merge) {
 320                        conflicts <<= 1;
 321                        if (src[0])
 322                                conflicts |= 1;
 323                }
 324                if (traverse_trees_recursive(n, dirmask, conflicts,
 325                                             names, info) < 0)
 326                        return -1;
 327                return mask;
 328        }
 329
 330        return mask;
 331}
 332
 333static int unpack_failed(struct unpack_trees_options *o, const char *message)
 334{
 335        discard_index(&o->result);
 336        if (!o->gently) {
 337                if (message)
 338                        return error("%s", message);
 339                return -1;
 340        }
 341        return -1;
 342}
 343
 344/*
 345 * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
 346 * resulting index, -2 on failure to reflect the changes to the work tree.
 347 */
 348int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
 349{
 350        int ret;
 351        static struct cache_entry *dfc;
 352
 353        if (len > MAX_UNPACK_TREES)
 354                die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
 355        memset(&state, 0, sizeof(state));
 356        state.base_dir = "";
 357        state.force = 1;
 358        state.quiet = 1;
 359        state.refresh_cache = 1;
 360
 361        memset(&o->result, 0, sizeof(o->result));
 362        o->result.initialized = 1;
 363        if (o->src_index)
 364                o->result.timestamp = o->src_index->timestamp;
 365        o->merge_size = len;
 366
 367        if (!dfc)
 368                dfc = xcalloc(1, cache_entry_size(0));
 369        o->df_conflict_entry = dfc;
 370
 371        if (len) {
 372                const char *prefix = o->prefix ? o->prefix : "";
 373                struct traverse_info info;
 374
 375                setup_traverse_info(&info, prefix);
 376                info.fn = unpack_callback;
 377                info.data = o;
 378
 379                if (traverse_trees(len, t, &info) < 0)
 380                        return unpack_failed(o, NULL);
 381        }
 382
 383        /* Any left-over entries in the index? */
 384        if (o->merge) {
 385                while (o->pos < o->src_index->cache_nr) {
 386                        struct cache_entry *ce = o->src_index->cache[o->pos];
 387                        if (unpack_index_entry(ce, o) < 0)
 388                                return unpack_failed(o, NULL);
 389                }
 390        }
 391
 392        if (o->trivial_merges_only && o->nontrivial_merge)
 393                return unpack_failed(o, "Merge requires file-level merging");
 394
 395        o->src_index = NULL;
 396        ret = check_updates(o) ? (-2) : 0;
 397        if (o->dst_index)
 398                *o->dst_index = o->result;
 399        return ret;
 400}
 401
 402/* Here come the merge functions */
 403
 404static int reject_merge(struct cache_entry *ce, struct unpack_trees_options *o)
 405{
 406        return error(ERRORMSG(o, would_overwrite), ce->name);
 407}
 408
 409static int same(struct cache_entry *a, struct cache_entry *b)
 410{
 411        if (!!a != !!b)
 412                return 0;
 413        if (!a && !b)
 414                return 1;
 415        return a->ce_mode == b->ce_mode &&
 416               !hashcmp(a->sha1, b->sha1);
 417}
 418
 419
 420/*
 421 * When a CE gets turned into an unmerged entry, we
 422 * want it to be up-to-date
 423 */
 424static int verify_uptodate(struct cache_entry *ce,
 425                struct unpack_trees_options *o)
 426{
 427        struct stat st;
 428
 429        if (o->index_only || o->reset)
 430                return 0;
 431
 432        if (!lstat(ce->name, &st)) {
 433                unsigned changed = ie_match_stat(o->src_index, ce, &st, CE_MATCH_IGNORE_VALID);
 434                if (!changed)
 435                        return 0;
 436                /*
 437                 * NEEDSWORK: the current default policy is to allow
 438                 * submodule to be out of sync wrt the supermodule
 439                 * index.  This needs to be tightened later for
 440                 * submodules that are marked to be automatically
 441                 * checked out.
 442                 */
 443                if (S_ISGITLINK(ce->ce_mode))
 444                        return 0;
 445                errno = 0;
 446        }
 447        if (errno == ENOENT)
 448                return 0;
 449        return o->gently ? -1 :
 450                error(ERRORMSG(o, not_uptodate_file), ce->name);
 451}
 452
 453static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
 454{
 455        if (ce)
 456                cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
 457}
 458
 459/*
 460 * Check that checking out ce->sha1 in subdir ce->name is not
 461 * going to overwrite any working files.
 462 *
 463 * Currently, git does not checkout subprojects during a superproject
 464 * checkout, so it is not going to overwrite anything.
 465 */
 466static int verify_clean_submodule(struct cache_entry *ce, const char *action,
 467                                      struct unpack_trees_options *o)
 468{
 469        return 0;
 470}
 471
 472static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
 473                                      struct unpack_trees_options *o)
 474{
 475        /*
 476         * we are about to extract "ce->name"; we would not want to lose
 477         * anything in the existing directory there.
 478         */
 479        int namelen;
 480        int i;
 481        struct dir_struct d;
 482        char *pathbuf;
 483        int cnt = 0;
 484        unsigned char sha1[20];
 485
 486        if (S_ISGITLINK(ce->ce_mode) &&
 487            resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
 488                /* If we are not going to update the submodule, then
 489                 * we don't care.
 490                 */
 491                if (!hashcmp(sha1, ce->sha1))
 492                        return 0;
 493                return verify_clean_submodule(ce, action, o);
 494        }
 495
 496        /*
 497         * First let's make sure we do not have a local modification
 498         * in that directory.
 499         */
 500        namelen = strlen(ce->name);
 501        for (i = o->pos; i < o->src_index->cache_nr; i++) {
 502                struct cache_entry *ce2 = o->src_index->cache[i];
 503                int len = ce_namelen(ce2);
 504                if (len < namelen ||
 505                    strncmp(ce->name, ce2->name, namelen) ||
 506                    ce2->name[namelen] != '/')
 507                        break;
 508                /*
 509                 * ce2->name is an entry in the subdirectory.
 510                 */
 511                if (!ce_stage(ce2)) {
 512                        if (verify_uptodate(ce2, o))
 513                                return -1;
 514                        add_entry(o, ce2, CE_REMOVE, 0);
 515                }
 516                cnt++;
 517        }
 518
 519        /*
 520         * Then we need to make sure that we do not lose a locally
 521         * present file that is not ignored.
 522         */
 523        pathbuf = xmalloc(namelen + 2);
 524        memcpy(pathbuf, ce->name, namelen);
 525        strcpy(pathbuf+namelen, "/");
 526
 527        memset(&d, 0, sizeof(d));
 528        if (o->dir)
 529                d.exclude_per_dir = o->dir->exclude_per_dir;
 530        i = read_directory(&d, ce->name, pathbuf, namelen+1, NULL);
 531        if (i)
 532                return o->gently ? -1 :
 533                        error(ERRORMSG(o, not_uptodate_dir), ce->name);
 534        free(pathbuf);
 535        return cnt;
 536}
 537
 538/*
 539 * This gets called when there was no index entry for the tree entry 'dst',
 540 * but we found a file in the working tree that 'lstat()' said was fine,
 541 * and we're on a case-insensitive filesystem.
 542 *
 543 * See if we can find a case-insensitive match in the index that also
 544 * matches the stat information, and assume it's that other file!
 545 */
 546static int icase_exists(struct unpack_trees_options *o, struct cache_entry *dst, struct stat *st)
 547{
 548        struct cache_entry *src;
 549
 550        src = index_name_exists(o->src_index, dst->name, ce_namelen(dst), 1);
 551        return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID);
 552}
 553
 554/*
 555 * We do not want to remove or overwrite a working tree file that
 556 * is not tracked, unless it is ignored.
 557 */
 558static int verify_absent(struct cache_entry *ce, const char *action,
 559                         struct unpack_trees_options *o)
 560{
 561        struct stat st;
 562
 563        if (o->index_only || o->reset || !o->update)
 564                return 0;
 565
 566        if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
 567                return 0;
 568
 569        if (!lstat(ce->name, &st)) {
 570                int ret;
 571                int dtype = ce_to_dtype(ce);
 572                struct cache_entry *result;
 573
 574                /*
 575                 * It may be that the 'lstat()' succeeded even though
 576                 * target 'ce' was absent, because there is an old
 577                 * entry that is different only in case..
 578                 *
 579                 * Ignore that lstat() if it matches.
 580                 */
 581                if (ignore_case && icase_exists(o, ce, &st))
 582                        return 0;
 583
 584                if (o->dir && excluded(o->dir, ce->name, &dtype))
 585                        /*
 586                         * ce->name is explicitly excluded, so it is Ok to
 587                         * overwrite it.
 588                         */
 589                        return 0;
 590                if (S_ISDIR(st.st_mode)) {
 591                        /*
 592                         * We are checking out path "foo" and
 593                         * found "foo/." in the working tree.
 594                         * This is tricky -- if we have modified
 595                         * files that are in "foo/" we would lose
 596                         * it.
 597                         */
 598                        ret = verify_clean_subdirectory(ce, action, o);
 599                        if (ret < 0)
 600                                return ret;
 601
 602                        /*
 603                         * If this removed entries from the index,
 604                         * what that means is:
 605                         *
 606                         * (1) the caller unpack_callback() saw path/foo
 607                         * in the index, and it has not removed it because
 608                         * it thinks it is handling 'path' as blob with
 609                         * D/F conflict;
 610                         * (2) we will return "ok, we placed a merged entry
 611                         * in the index" which would cause o->pos to be
 612                         * incremented by one;
 613                         * (3) however, original o->pos now has 'path/foo'
 614                         * marked with "to be removed".
 615                         *
 616                         * We need to increment it by the number of
 617                         * deleted entries here.
 618                         */
 619                        o->pos += ret;
 620                        return 0;
 621                }
 622
 623                /*
 624                 * The previous round may already have decided to
 625                 * delete this path, which is in a subdirectory that
 626                 * is being replaced with a blob.
 627                 */
 628                result = index_name_exists(&o->result, ce->name, ce_namelen(ce), 0);
 629                if (result) {
 630                        if (result->ce_flags & CE_REMOVE)
 631                                return 0;
 632                }
 633
 634                return o->gently ? -1 :
 635                        error(ERRORMSG(o, would_lose_untracked), ce->name, action);
 636        }
 637        return 0;
 638}
 639
 640static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 641                struct unpack_trees_options *o)
 642{
 643        int update = CE_UPDATE;
 644
 645        if (old) {
 646                /*
 647                 * See if we can re-use the old CE directly?
 648                 * That way we get the uptodate stat info.
 649                 *
 650                 * This also removes the UPDATE flag on a match; otherwise
 651                 * we will end up overwriting local changes in the work tree.
 652                 */
 653                if (same(old, merge)) {
 654                        copy_cache_entry(merge, old);
 655                        update = 0;
 656                } else {
 657                        if (verify_uptodate(old, o))
 658                                return -1;
 659                        invalidate_ce_path(old, o);
 660                }
 661        }
 662        else {
 663                if (verify_absent(merge, "overwritten", o))
 664                        return -1;
 665                invalidate_ce_path(merge, o);
 666        }
 667
 668        add_entry(o, merge, update, CE_STAGEMASK);
 669        return 1;
 670}
 671
 672static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
 673                struct unpack_trees_options *o)
 674{
 675        /* Did it exist in the index? */
 676        if (!old) {
 677                if (verify_absent(ce, "removed", o))
 678                        return -1;
 679                return 0;
 680        }
 681        if (verify_uptodate(old, o))
 682                return -1;
 683        add_entry(o, ce, CE_REMOVE, 0);
 684        invalidate_ce_path(ce, o);
 685        return 1;
 686}
 687
 688static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
 689{
 690        add_entry(o, ce, 0, 0);
 691        return 1;
 692}
 693
 694#if DBRT_DEBUG
 695static void show_stage_entry(FILE *o,
 696                             const char *label, const struct cache_entry *ce)
 697{
 698        if (!ce)
 699                fprintf(o, "%s (missing)\n", label);
 700        else
 701                fprintf(o, "%s%06o %s %d\t%s\n",
 702                        label,
 703                        ce->ce_mode,
 704                        sha1_to_hex(ce->sha1),
 705                        ce_stage(ce),
 706                        ce->name);
 707}
 708#endif
 709
 710int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
 711{
 712        struct cache_entry *index;
 713        struct cache_entry *head;
 714        struct cache_entry *remote = stages[o->head_idx + 1];
 715        int count;
 716        int head_match = 0;
 717        int remote_match = 0;
 718
 719        int df_conflict_head = 0;
 720        int df_conflict_remote = 0;
 721
 722        int any_anc_missing = 0;
 723        int no_anc_exists = 1;
 724        int i;
 725
 726        for (i = 1; i < o->head_idx; i++) {
 727                if (!stages[i] || stages[i] == o->df_conflict_entry)
 728                        any_anc_missing = 1;
 729                else
 730                        no_anc_exists = 0;
 731        }
 732
 733        index = stages[0];
 734        head = stages[o->head_idx];
 735
 736        if (head == o->df_conflict_entry) {
 737                df_conflict_head = 1;
 738                head = NULL;
 739        }
 740
 741        if (remote == o->df_conflict_entry) {
 742                df_conflict_remote = 1;
 743                remote = NULL;
 744        }
 745
 746        /* First, if there's a #16 situation, note that to prevent #13
 747         * and #14.
 748         */
 749        if (!same(remote, head)) {
 750                for (i = 1; i < o->head_idx; i++) {
 751                        if (same(stages[i], head)) {
 752                                head_match = i;
 753                        }
 754                        if (same(stages[i], remote)) {
 755                                remote_match = i;
 756                        }
 757                }
 758        }
 759
 760        /* We start with cases where the index is allowed to match
 761         * something other than the head: #14(ALT) and #2ALT, where it
 762         * is permitted to match the result instead.
 763         */
 764        /* #14, #14ALT, #2ALT */
 765        if (remote && !df_conflict_head && head_match && !remote_match) {
 766                if (index && !same(index, remote) && !same(index, head))
 767                        return o->gently ? -1 : reject_merge(index, o);
 768                return merged_entry(remote, index, o);
 769        }
 770        /*
 771         * If we have an entry in the index cache, then we want to
 772         * make sure that it matches head.
 773         */
 774        if (index && !same(index, head))
 775                return o->gently ? -1 : reject_merge(index, o);
 776
 777        if (head) {
 778                /* #5ALT, #15 */
 779                if (same(head, remote))
 780                        return merged_entry(head, index, o);
 781                /* #13, #3ALT */
 782                if (!df_conflict_remote && remote_match && !head_match)
 783                        return merged_entry(head, index, o);
 784        }
 785
 786        /* #1 */
 787        if (!head && !remote && any_anc_missing)
 788                return 0;
 789
 790        /* Under the new "aggressive" rule, we resolve mostly trivial
 791         * cases that we historically had git-merge-one-file resolve.
 792         */
 793        if (o->aggressive) {
 794                int head_deleted = !head && !df_conflict_head;
 795                int remote_deleted = !remote && !df_conflict_remote;
 796                struct cache_entry *ce = NULL;
 797
 798                if (index)
 799                        ce = index;
 800                else if (head)
 801                        ce = head;
 802                else if (remote)
 803                        ce = remote;
 804                else {
 805                        for (i = 1; i < o->head_idx; i++) {
 806                                if (stages[i] && stages[i] != o->df_conflict_entry) {
 807                                        ce = stages[i];
 808                                        break;
 809                                }
 810                        }
 811                }
 812
 813                /*
 814                 * Deleted in both.
 815                 * Deleted in one and unchanged in the other.
 816                 */
 817                if ((head_deleted && remote_deleted) ||
 818                    (head_deleted && remote && remote_match) ||
 819                    (remote_deleted && head && head_match)) {
 820                        if (index)
 821                                return deleted_entry(index, index, o);
 822                        if (ce && !head_deleted) {
 823                                if (verify_absent(ce, "removed", o))
 824                                        return -1;
 825                        }
 826                        return 0;
 827                }
 828                /*
 829                 * Added in both, identically.
 830                 */
 831                if (no_anc_exists && head && remote && same(head, remote))
 832                        return merged_entry(head, index, o);
 833
 834        }
 835
 836        /* Below are "no merge" cases, which require that the index be
 837         * up-to-date to avoid the files getting overwritten with
 838         * conflict resolution files.
 839         */
 840        if (index) {
 841                if (verify_uptodate(index, o))
 842                        return -1;
 843        }
 844
 845        o->nontrivial_merge = 1;
 846
 847        /* #2, #3, #4, #6, #7, #9, #10, #11. */
 848        count = 0;
 849        if (!head_match || !remote_match) {
 850                for (i = 1; i < o->head_idx; i++) {
 851                        if (stages[i] && stages[i] != o->df_conflict_entry) {
 852                                keep_entry(stages[i], o);
 853                                count++;
 854                                break;
 855                        }
 856                }
 857        }
 858#if DBRT_DEBUG
 859        else {
 860                fprintf(stderr, "read-tree: warning #16 detected\n");
 861                show_stage_entry(stderr, "head   ", stages[head_match]);
 862                show_stage_entry(stderr, "remote ", stages[remote_match]);
 863        }
 864#endif
 865        if (head) { count += keep_entry(head, o); }
 866        if (remote) { count += keep_entry(remote, o); }
 867        return count;
 868}
 869
 870/*
 871 * Two-way merge.
 872 *
 873 * The rule is to "carry forward" what is in the index without losing
 874 * information across a "fast forward", favoring a successful merge
 875 * over a merge failure when it makes sense.  For details of the
 876 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
 877 *
 878 */
 879int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
 880{
 881        struct cache_entry *current = src[0];
 882        struct cache_entry *oldtree = src[1];
 883        struct cache_entry *newtree = src[2];
 884
 885        if (o->merge_size != 2)
 886                return error("Cannot do a twoway merge of %d trees",
 887                             o->merge_size);
 888
 889        if (oldtree == o->df_conflict_entry)
 890                oldtree = NULL;
 891        if (newtree == o->df_conflict_entry)
 892                newtree = NULL;
 893
 894        if (current) {
 895                if ((!oldtree && !newtree) || /* 4 and 5 */
 896                    (!oldtree && newtree &&
 897                     same(current, newtree)) || /* 6 and 7 */
 898                    (oldtree && newtree &&
 899                     same(oldtree, newtree)) || /* 14 and 15 */
 900                    (oldtree && newtree &&
 901                     !same(oldtree, newtree) && /* 18 and 19 */
 902                     same(current, newtree))) {
 903                        return keep_entry(current, o);
 904                }
 905                else if (oldtree && !newtree && same(current, oldtree)) {
 906                        /* 10 or 11 */
 907                        return deleted_entry(oldtree, current, o);
 908                }
 909                else if (oldtree && newtree &&
 910                         same(current, oldtree) && !same(current, newtree)) {
 911                        /* 20 or 21 */
 912                        return merged_entry(newtree, current, o);
 913                }
 914                else {
 915                        /* all other failures */
 916                        if (oldtree)
 917                                return o->gently ? -1 : reject_merge(oldtree, o);
 918                        if (current)
 919                                return o->gently ? -1 : reject_merge(current, o);
 920                        if (newtree)
 921                                return o->gently ? -1 : reject_merge(newtree, o);
 922                        return -1;
 923                }
 924        }
 925        else if (newtree) {
 926                if (oldtree && !o->initial_checkout) {
 927                        /*
 928                         * deletion of the path was staged;
 929                         */
 930                        if (same(oldtree, newtree))
 931                                return 1;
 932                        return reject_merge(oldtree, o);
 933                }
 934                return merged_entry(newtree, current, o);
 935        }
 936        return deleted_entry(oldtree, current, o);
 937}
 938
 939/*
 940 * Bind merge.
 941 *
 942 * Keep the index entries at stage0, collapse stage1 but make sure
 943 * stage0 does not have anything there.
 944 */
 945int bind_merge(struct cache_entry **src,
 946                struct unpack_trees_options *o)
 947{
 948        struct cache_entry *old = src[0];
 949        struct cache_entry *a = src[1];
 950
 951        if (o->merge_size != 1)
 952                return error("Cannot do a bind merge of %d trees\n",
 953                             o->merge_size);
 954        if (a && old)
 955                return o->gently ? -1 :
 956                        error(ERRORMSG(o, bind_overlap), a->name, old->name);
 957        if (!a)
 958                return keep_entry(old, o);
 959        else
 960                return merged_entry(a, NULL, o);
 961}
 962
 963/*
 964 * One-way merge.
 965 *
 966 * The rule is:
 967 * - take the stat information from stage0, take the data from stage1
 968 */
 969int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
 970{
 971        struct cache_entry *old = src[0];
 972        struct cache_entry *a = src[1];
 973
 974        if (o->merge_size != 1)
 975                return error("Cannot do a oneway merge of %d trees",
 976                             o->merge_size);
 977
 978        if (!a)
 979                return deleted_entry(old, old, o);
 980
 981        if (old && same(old, a)) {
 982                int update = 0;
 983                if (o->reset) {
 984                        struct stat st;
 985                        if (lstat(old->name, &st) ||
 986                            ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID))
 987                                update |= CE_UPDATE;
 988                }
 989                add_entry(o, old, update, 0);
 990                return 0;
 991        }
 992        return merged_entry(a, old, o);
 993}