feae846226237fce9b4ff4a4810a9961637a4ca5
   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
  11static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
  12        unsigned int set, unsigned int clear)
  13{
  14        unsigned int size = ce_size(ce);
  15        struct cache_entry *new = xmalloc(size);
  16
  17        clear |= CE_HASHED | CE_UNHASHED;
  18
  19        memcpy(new, ce, size);
  20        new->next = NULL;
  21        new->ce_flags = (new->ce_flags & ~clear) | set;
  22        add_index_entry(&o->result, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE|ADD_CACHE_SKIP_DFCHECK);
  23}
  24
  25/* Unlink the last component and attempt to remove leading
  26 * directories, in case this unlink is the removal of the
  27 * last entry in the directory -- empty directories are removed.
  28 */
  29static void unlink_entry(char *name, char *last_symlink)
  30{
  31        char *cp, *prev;
  32
  33        if (has_symlink_leading_path(name, last_symlink))
  34                return;
  35        if (unlink(name))
  36                return;
  37        prev = NULL;
  38        while (1) {
  39                int status;
  40                cp = strrchr(name, '/');
  41                if (prev)
  42                        *prev = '/';
  43                if (!cp)
  44                        break;
  45
  46                *cp = 0;
  47                status = rmdir(name);
  48                if (status) {
  49                        *cp = '/';
  50                        break;
  51                }
  52                prev = cp;
  53        }
  54}
  55
  56static struct checkout state;
  57static int check_updates(struct unpack_trees_options *o)
  58{
  59        unsigned cnt = 0, total = 0;
  60        struct progress *progress = NULL;
  61        char last_symlink[PATH_MAX];
  62        struct index_state *index = &o->result;
  63        int i;
  64        int errs = 0;
  65
  66        if (o->update && o->verbose_update) {
  67                for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
  68                        struct cache_entry *ce = index->cache[cnt];
  69                        if (ce->ce_flags & (CE_UPDATE | CE_REMOVE))
  70                                total++;
  71                }
  72
  73                progress = start_progress_delay("Checking out files",
  74                                                total, 50, 1);
  75                cnt = 0;
  76        }
  77
  78        *last_symlink = '\0';
  79        for (i = 0; i < index->cache_nr; i++) {
  80                struct cache_entry *ce = index->cache[i];
  81
  82                if (ce->ce_flags & CE_REMOVE) {
  83                        display_progress(progress, ++cnt);
  84                        if (o->update)
  85                                unlink_entry(ce->name, last_symlink);
  86                        remove_index_entry_at(&o->result, i);
  87                        i--;
  88                        continue;
  89                }
  90        }
  91
  92        for (i = 0; i < index->cache_nr; i++) {
  93                struct cache_entry *ce = index->cache[i];
  94
  95                if (ce->ce_flags & CE_UPDATE) {
  96                        display_progress(progress, ++cnt);
  97                        ce->ce_flags &= ~CE_UPDATE;
  98                        if (o->update) {
  99                                errs |= checkout_entry(ce, &state, NULL);
 100                                *last_symlink = '\0';
 101                        }
 102                }
 103        }
 104        stop_progress(&progress);
 105        return errs != 0;
 106}
 107
 108static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
 109{
 110        int ret = o->fn(src, o);
 111        if (ret > 0)
 112                ret = 0;
 113        return ret;
 114}
 115
 116static int unpack_index_entry(struct cache_entry *ce, struct unpack_trees_options *o)
 117{
 118        struct cache_entry *src[5] = { ce, };
 119
 120        o->pos++;
 121        if (ce_stage(ce)) {
 122                if (o->skip_unmerged) {
 123                        add_entry(o, ce, 0, 0);
 124                        return 0;
 125                }
 126        }
 127        return call_unpack_fn(src, o);
 128}
 129
 130int traverse_trees_recursive(int n, unsigned long dirmask, unsigned long df_conflicts, struct name_entry *names, struct traverse_info *info)
 131{
 132        int i;
 133        struct tree_desc t[MAX_UNPACK_TREES];
 134        struct traverse_info newinfo;
 135        struct name_entry *p;
 136
 137        p = names;
 138        while (!p->mode)
 139                p++;
 140
 141        newinfo = *info;
 142        newinfo.prev = info;
 143        newinfo.name = *p;
 144        newinfo.pathlen += tree_entry_len(p->path, p->sha1) + 1;
 145        newinfo.conflicts |= df_conflicts;
 146
 147        for (i = 0; i < n; i++, dirmask >>= 1) {
 148                const unsigned char *sha1 = NULL;
 149                if (dirmask & 1)
 150                        sha1 = names[i].sha1;
 151                fill_tree_descriptor(t+i, sha1);
 152        }
 153        return traverse_trees(n, t, &newinfo);
 154}
 155
 156/*
 157 * Compare the traverse-path to the cache entry without actually
 158 * having to generate the textual representation of the traverse
 159 * path.
 160 *
 161 * NOTE! This *only* compares up to the size of the traverse path
 162 * itself - the caller needs to do the final check for the cache
 163 * entry having more data at the end!
 164 */
 165static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 166{
 167        int len, pathlen, ce_len;
 168        const char *ce_name;
 169
 170        if (info->prev) {
 171                int cmp = do_compare_entry(ce, info->prev, &info->name);
 172                if (cmp)
 173                        return cmp;
 174        }
 175        pathlen = info->pathlen;
 176        ce_len = ce_namelen(ce);
 177
 178        /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 179        if (ce_len < pathlen)
 180                return -1;
 181
 182        ce_len -= pathlen;
 183        ce_name = ce->name + pathlen;
 184
 185        len = tree_entry_len(n->path, n->sha1);
 186        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 187}
 188
 189static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 190{
 191        int cmp = do_compare_entry(ce, info, n);
 192        if (cmp)
 193                return cmp;
 194
 195        /*
 196         * Even if the beginning compared identically, the ce should
 197         * compare as bigger than a directory leading up to it!
 198         */
 199        return ce_namelen(ce) > traverse_path_len(info, n);
 200}
 201
 202static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
 203{
 204        int len = traverse_path_len(info, n);
 205        struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
 206
 207        ce->ce_mode = create_ce_mode(n->mode);
 208        ce->ce_flags = create_ce_flags(len, stage);
 209        hashcpy(ce->sha1, n->sha1);
 210        make_traverse_path(ce->name, info, n);
 211
 212        return ce;
 213}
 214
 215static int unpack_nondirectories(int n, unsigned long mask, unsigned long dirmask, struct cache_entry *src[5],
 216        const struct name_entry *names, const struct traverse_info *info)
 217{
 218        int i;
 219        struct unpack_trees_options *o = info->data;
 220        unsigned long conflicts;
 221
 222        /* Do we have *only* directories? Nothing to do */
 223        if (mask == dirmask && !src[0])
 224                return 0;
 225
 226        conflicts = info->conflicts;
 227        if (o->merge)
 228                conflicts >>= 1;
 229        conflicts |= dirmask;
 230
 231        /*
 232         * Ok, we've filled in up to any potential index entry in src[0],
 233         * now do the rest.
 234         */
 235        for (i = 0; i < n; i++) {
 236                int stage;
 237                unsigned int bit = 1ul << i;
 238                if (conflicts & bit) {
 239                        src[i + o->merge] = o->df_conflict_entry;
 240                        continue;
 241                }
 242                if (!(mask & bit))
 243                        continue;
 244                if (!o->merge)
 245                        stage = 0;
 246                else if (i + 1 < o->head_idx)
 247                        stage = 1;
 248                else if (i + 1 > o->head_idx)
 249                        stage = 3;
 250                else
 251                        stage = 2;
 252                src[i + o->merge] = create_ce_entry(info, names + i, stage);
 253        }
 254
 255        if (o->merge)
 256                return call_unpack_fn(src, o);
 257
 258        n += o->merge;
 259        for (i = 0; i < n; i++)
 260                add_entry(o, src[i], 0, 0);
 261        return 0;
 262}
 263
 264static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
 265{
 266        struct cache_entry *src[5] = { NULL, };
 267        struct unpack_trees_options *o = info->data;
 268        const struct name_entry *p = names;
 269
 270        /* Find first entry with a real name (we could use "mask" too) */
 271        while (!p->mode)
 272                p++;
 273
 274        /* Are we supposed to look at the index too? */
 275        if (o->merge) {
 276                while (o->pos < o->src_index->cache_nr) {
 277                        struct cache_entry *ce = o->src_index->cache[o->pos];
 278                        int cmp = compare_entry(ce, info, p);
 279                        if (cmp < 0) {
 280                                if (unpack_index_entry(ce, o) < 0)
 281                                        return -1;
 282                                continue;
 283                        }
 284                        if (!cmp) {
 285                                o->pos++;
 286                                if (ce_stage(ce)) {
 287                                        /*
 288                                         * If we skip unmerged index entries, we'll skip this
 289                                         * entry *and* the tree entries associated with it!
 290                                         */
 291                                        if (o->skip_unmerged) {
 292                                                add_entry(o, ce, 0, 0);
 293                                                return mask;
 294                                        }
 295                                }
 296                                src[0] = ce;
 297                        }
 298                        break;
 299                }
 300        }
 301
 302        if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
 303                return -1;
 304
 305        /* Now handle any directories.. */
 306        if (dirmask) {
 307                unsigned long conflicts = mask & ~dirmask;
 308                if (o->merge) {
 309                        conflicts <<= 1;
 310                        if (src[0])
 311                                conflicts |= 1;
 312                }
 313                if (traverse_trees_recursive(n, dirmask, conflicts,
 314                                             names, info) < 0)
 315                        return -1;
 316                return mask;
 317        }
 318
 319        return mask;
 320}
 321
 322static int unpack_failed(struct unpack_trees_options *o, const char *message)
 323{
 324        discard_index(&o->result);
 325        if (!o->gently) {
 326                if (message)
 327                        return error(message);
 328                return -1;
 329        }
 330        return -1;
 331}
 332
 333int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
 334{
 335        static struct cache_entry *dfc;
 336
 337        if (len > MAX_UNPACK_TREES)
 338                die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
 339        memset(&state, 0, sizeof(state));
 340        state.base_dir = "";
 341        state.force = 1;
 342        state.quiet = 1;
 343        state.refresh_cache = 1;
 344
 345        memset(&o->result, 0, sizeof(o->result));
 346        if (o->src_index)
 347                o->result.timestamp = o->src_index->timestamp;
 348        o->merge_size = len;
 349
 350        if (!dfc)
 351                dfc = xcalloc(1, sizeof(struct cache_entry) + 1);
 352        o->df_conflict_entry = dfc;
 353
 354        if (len) {
 355                const char *prefix = o->prefix ? o->prefix : "";
 356                struct traverse_info info;
 357
 358                setup_traverse_info(&info, prefix);
 359                info.fn = unpack_callback;
 360                info.data = o;
 361
 362                if (traverse_trees(len, t, &info) < 0)
 363                        return unpack_failed(o, NULL);
 364        }
 365
 366        /* Any left-over entries in the index? */
 367        if (o->merge) {
 368                while (o->pos < o->src_index->cache_nr) {
 369                        struct cache_entry *ce = o->src_index->cache[o->pos];
 370                        if (unpack_index_entry(ce, o) < 0)
 371                                return unpack_failed(o, NULL);
 372                }
 373        }
 374
 375        if (o->trivial_merges_only && o->nontrivial_merge)
 376                return unpack_failed(o, "Merge requires file-level merging");
 377
 378        o->src_index = NULL;
 379        if (check_updates(o))
 380                return -1;
 381        if (o->dst_index)
 382                *o->dst_index = o->result;
 383        return 0;
 384}
 385
 386/* Here come the merge functions */
 387
 388static int reject_merge(struct cache_entry *ce)
 389{
 390        return error("Entry '%s' would be overwritten by merge. Cannot merge.",
 391                     ce->name);
 392}
 393
 394static int same(struct cache_entry *a, struct cache_entry *b)
 395{
 396        if (!!a != !!b)
 397                return 0;
 398        if (!a && !b)
 399                return 1;
 400        return a->ce_mode == b->ce_mode &&
 401               !hashcmp(a->sha1, b->sha1);
 402}
 403
 404
 405/*
 406 * When a CE gets turned into an unmerged entry, we
 407 * want it to be up-to-date
 408 */
 409static int verify_uptodate(struct cache_entry *ce,
 410                struct unpack_trees_options *o)
 411{
 412        struct stat st;
 413
 414        if (o->index_only || o->reset)
 415                return 0;
 416
 417        if (!lstat(ce->name, &st)) {
 418                unsigned changed = ie_match_stat(o->src_index, ce, &st, CE_MATCH_IGNORE_VALID);
 419                if (!changed)
 420                        return 0;
 421                /*
 422                 * NEEDSWORK: the current default policy is to allow
 423                 * submodule to be out of sync wrt the supermodule
 424                 * index.  This needs to be tightened later for
 425                 * submodules that are marked to be automatically
 426                 * checked out.
 427                 */
 428                if (S_ISGITLINK(ce->ce_mode))
 429                        return 0;
 430                errno = 0;
 431        }
 432        if (errno == ENOENT)
 433                return 0;
 434        return o->gently ? -1 :
 435                error("Entry '%s' not uptodate. Cannot merge.", ce->name);
 436}
 437
 438static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
 439{
 440        if (ce)
 441                cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
 442}
 443
 444/*
 445 * Check that checking out ce->sha1 in subdir ce->name is not
 446 * going to overwrite any working files.
 447 *
 448 * Currently, git does not checkout subprojects during a superproject
 449 * checkout, so it is not going to overwrite anything.
 450 */
 451static int verify_clean_submodule(struct cache_entry *ce, const char *action,
 452                                      struct unpack_trees_options *o)
 453{
 454        return 0;
 455}
 456
 457static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
 458                                      struct unpack_trees_options *o)
 459{
 460        /*
 461         * we are about to extract "ce->name"; we would not want to lose
 462         * anything in the existing directory there.
 463         */
 464        int namelen;
 465        int pos, i;
 466        struct dir_struct d;
 467        char *pathbuf;
 468        int cnt = 0;
 469        unsigned char sha1[20];
 470
 471        if (S_ISGITLINK(ce->ce_mode) &&
 472            resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
 473                /* If we are not going to update the submodule, then
 474                 * we don't care.
 475                 */
 476                if (!hashcmp(sha1, ce->sha1))
 477                        return 0;
 478                return verify_clean_submodule(ce, action, o);
 479        }
 480
 481        /*
 482         * First let's make sure we do not have a local modification
 483         * in that directory.
 484         */
 485        namelen = strlen(ce->name);
 486        pos = index_name_pos(o->src_index, ce->name, namelen);
 487        if (0 <= pos)
 488                return cnt; /* we have it as nondirectory */
 489        pos = -pos - 1;
 490        for (i = pos; i < o->src_index->cache_nr; i++) {
 491                struct cache_entry *ce = o->src_index->cache[i];
 492                int len = ce_namelen(ce);
 493                if (len < namelen ||
 494                    strncmp(ce->name, ce->name, namelen) ||
 495                    ce->name[namelen] != '/')
 496                        break;
 497                /*
 498                 * ce->name is an entry in the subdirectory.
 499                 */
 500                if (!ce_stage(ce)) {
 501                        if (verify_uptodate(ce, o))
 502                                return -1;
 503                        add_entry(o, ce, CE_REMOVE, 0);
 504                }
 505                cnt++;
 506        }
 507
 508        /*
 509         * Then we need to make sure that we do not lose a locally
 510         * present file that is not ignored.
 511         */
 512        pathbuf = xmalloc(namelen + 2);
 513        memcpy(pathbuf, ce->name, namelen);
 514        strcpy(pathbuf+namelen, "/");
 515
 516        memset(&d, 0, sizeof(d));
 517        if (o->dir)
 518                d.exclude_per_dir = o->dir->exclude_per_dir;
 519        i = read_directory(&d, ce->name, pathbuf, namelen+1, NULL);
 520        if (i)
 521                return o->gently ? -1 :
 522                        error("Updating '%s' would lose untracked files in it",
 523                              ce->name);
 524        free(pathbuf);
 525        return cnt;
 526}
 527
 528/*
 529 * This gets called when there was no index entry for the tree entry 'dst',
 530 * but we found a file in the working tree that 'lstat()' said was fine,
 531 * and we're on a case-insensitive filesystem.
 532 *
 533 * See if we can find a case-insensitive match in the index that also
 534 * matches the stat information, and assume it's that other file!
 535 */
 536static int icase_exists(struct unpack_trees_options *o, struct cache_entry *dst, struct stat *st)
 537{
 538        struct cache_entry *src;
 539
 540        src = index_name_exists(o->src_index, dst->name, ce_namelen(dst), 1);
 541        return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID);
 542}
 543
 544/*
 545 * We do not want to remove or overwrite a working tree file that
 546 * is not tracked, unless it is ignored.
 547 */
 548static int verify_absent(struct cache_entry *ce, const char *action,
 549                         struct unpack_trees_options *o)
 550{
 551        struct stat st;
 552
 553        if (o->index_only || o->reset || !o->update)
 554                return 0;
 555
 556        if (has_symlink_leading_path(ce->name, NULL))
 557                return 0;
 558
 559        if (!lstat(ce->name, &st)) {
 560                int cnt;
 561                int dtype = ce_to_dtype(ce);
 562                struct cache_entry *result;
 563
 564                /*
 565                 * It may be that the 'lstat()' succeeded even though
 566                 * target 'ce' was absent, because there is an old
 567                 * entry that is different only in case..
 568                 *
 569                 * Ignore that lstat() if it matches.
 570                 */
 571                if (ignore_case && icase_exists(o, ce, &st))
 572                        return 0;
 573
 574                if (o->dir && excluded(o->dir, ce->name, &dtype))
 575                        /*
 576                         * ce->name is explicitly excluded, so it is Ok to
 577                         * overwrite it.
 578                         */
 579                        return 0;
 580                if (S_ISDIR(st.st_mode)) {
 581                        /*
 582                         * We are checking out path "foo" and
 583                         * found "foo/." in the working tree.
 584                         * This is tricky -- if we have modified
 585                         * files that are in "foo/" we would lose
 586                         * it.
 587                         */
 588                        cnt = verify_clean_subdirectory(ce, action, o);
 589
 590                        /*
 591                         * If this removed entries from the index,
 592                         * what that means is:
 593                         *
 594                         * (1) the caller unpack_trees_rec() saw path/foo
 595                         * in the index, and it has not removed it because
 596                         * it thinks it is handling 'path' as blob with
 597                         * D/F conflict;
 598                         * (2) we will return "ok, we placed a merged entry
 599                         * in the index" which would cause o->pos to be
 600                         * incremented by one;
 601                         * (3) however, original o->pos now has 'path/foo'
 602                         * marked with "to be removed".
 603                         *
 604                         * We need to increment it by the number of
 605                         * deleted entries here.
 606                         */
 607                        o->pos += cnt;
 608                        return 0;
 609                }
 610
 611                /*
 612                 * The previous round may already have decided to
 613                 * delete this path, which is in a subdirectory that
 614                 * is being replaced with a blob.
 615                 */
 616                result = index_name_exists(&o->result, ce->name, ce_namelen(ce), 0);
 617                if (result) {
 618                        if (result->ce_flags & CE_REMOVE)
 619                                return 0;
 620                }
 621
 622                return o->gently ? -1 :
 623                        error("Untracked working tree file '%s' "
 624                              "would be %s by merge.", ce->name, action);
 625        }
 626        return 0;
 627}
 628
 629static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 630                struct unpack_trees_options *o)
 631{
 632        int update = CE_UPDATE;
 633
 634        if (old) {
 635                /*
 636                 * See if we can re-use the old CE directly?
 637                 * That way we get the uptodate stat info.
 638                 *
 639                 * This also removes the UPDATE flag on a match; otherwise
 640                 * we will end up overwriting local changes in the work tree.
 641                 */
 642                if (same(old, merge)) {
 643                        copy_cache_entry(merge, old);
 644                        update = 0;
 645                } else {
 646                        if (verify_uptodate(old, o))
 647                                return -1;
 648                        invalidate_ce_path(old, o);
 649                }
 650        }
 651        else {
 652                if (verify_absent(merge, "overwritten", o))
 653                        return -1;
 654                invalidate_ce_path(merge, o);
 655        }
 656
 657        add_entry(o, merge, update, CE_STAGEMASK);
 658        return 1;
 659}
 660
 661static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
 662                struct unpack_trees_options *o)
 663{
 664        /* Did it exist in the index? */
 665        if (!old) {
 666                if (verify_absent(ce, "removed", o))
 667                        return -1;
 668                return 0;
 669        }
 670        if (verify_uptodate(old, o))
 671                return -1;
 672        add_entry(o, ce, CE_REMOVE, 0);
 673        invalidate_ce_path(ce, o);
 674        return 1;
 675}
 676
 677static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
 678{
 679        add_entry(o, ce, 0, 0);
 680        return 1;
 681}
 682
 683#if DBRT_DEBUG
 684static void show_stage_entry(FILE *o,
 685                             const char *label, const struct cache_entry *ce)
 686{
 687        if (!ce)
 688                fprintf(o, "%s (missing)\n", label);
 689        else
 690                fprintf(o, "%s%06o %s %d\t%s\n",
 691                        label,
 692                        ce->ce_mode,
 693                        sha1_to_hex(ce->sha1),
 694                        ce_stage(ce),
 695                        ce->name);
 696}
 697#endif
 698
 699int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
 700{
 701        struct cache_entry *index;
 702        struct cache_entry *head;
 703        struct cache_entry *remote = stages[o->head_idx + 1];
 704        int count;
 705        int head_match = 0;
 706        int remote_match = 0;
 707
 708        int df_conflict_head = 0;
 709        int df_conflict_remote = 0;
 710
 711        int any_anc_missing = 0;
 712        int no_anc_exists = 1;
 713        int i;
 714
 715        for (i = 1; i < o->head_idx; i++) {
 716                if (!stages[i] || stages[i] == o->df_conflict_entry)
 717                        any_anc_missing = 1;
 718                else
 719                        no_anc_exists = 0;
 720        }
 721
 722        index = stages[0];
 723        head = stages[o->head_idx];
 724
 725        if (head == o->df_conflict_entry) {
 726                df_conflict_head = 1;
 727                head = NULL;
 728        }
 729
 730        if (remote == o->df_conflict_entry) {
 731                df_conflict_remote = 1;
 732                remote = NULL;
 733        }
 734
 735        /* First, if there's a #16 situation, note that to prevent #13
 736         * and #14.
 737         */
 738        if (!same(remote, head)) {
 739                for (i = 1; i < o->head_idx; i++) {
 740                        if (same(stages[i], head)) {
 741                                head_match = i;
 742                        }
 743                        if (same(stages[i], remote)) {
 744                                remote_match = i;
 745                        }
 746                }
 747        }
 748
 749        /* We start with cases where the index is allowed to match
 750         * something other than the head: #14(ALT) and #2ALT, where it
 751         * is permitted to match the result instead.
 752         */
 753        /* #14, #14ALT, #2ALT */
 754        if (remote && !df_conflict_head && head_match && !remote_match) {
 755                if (index && !same(index, remote) && !same(index, head))
 756                        return o->gently ? -1 : reject_merge(index);
 757                return merged_entry(remote, index, o);
 758        }
 759        /*
 760         * If we have an entry in the index cache, then we want to
 761         * make sure that it matches head.
 762         */
 763        if (index && !same(index, head))
 764                return o->gently ? -1 : reject_merge(index);
 765
 766        if (head) {
 767                /* #5ALT, #15 */
 768                if (same(head, remote))
 769                        return merged_entry(head, index, o);
 770                /* #13, #3ALT */
 771                if (!df_conflict_remote && remote_match && !head_match)
 772                        return merged_entry(head, index, o);
 773        }
 774
 775        /* #1 */
 776        if (!head && !remote && any_anc_missing)
 777                return 0;
 778
 779        /* Under the new "aggressive" rule, we resolve mostly trivial
 780         * cases that we historically had git-merge-one-file resolve.
 781         */
 782        if (o->aggressive) {
 783                int head_deleted = !head && !df_conflict_head;
 784                int remote_deleted = !remote && !df_conflict_remote;
 785                struct cache_entry *ce = NULL;
 786
 787                if (index)
 788                        ce = index;
 789                else if (head)
 790                        ce = head;
 791                else if (remote)
 792                        ce = remote;
 793                else {
 794                        for (i = 1; i < o->head_idx; i++) {
 795                                if (stages[i] && stages[i] != o->df_conflict_entry) {
 796                                        ce = stages[i];
 797                                        break;
 798                                }
 799                        }
 800                }
 801
 802                /*
 803                 * Deleted in both.
 804                 * Deleted in one and unchanged in the other.
 805                 */
 806                if ((head_deleted && remote_deleted) ||
 807                    (head_deleted && remote && remote_match) ||
 808                    (remote_deleted && head && head_match)) {
 809                        if (index)
 810                                return deleted_entry(index, index, o);
 811                        if (ce && !head_deleted) {
 812                                if (verify_absent(ce, "removed", o))
 813                                        return -1;
 814                        }
 815                        return 0;
 816                }
 817                /*
 818                 * Added in both, identically.
 819                 */
 820                if (no_anc_exists && head && remote && same(head, remote))
 821                        return merged_entry(head, index, o);
 822
 823        }
 824
 825        /* Below are "no merge" cases, which require that the index be
 826         * up-to-date to avoid the files getting overwritten with
 827         * conflict resolution files.
 828         */
 829        if (index) {
 830                if (verify_uptodate(index, o))
 831                        return -1;
 832        }
 833
 834        o->nontrivial_merge = 1;
 835
 836        /* #2, #3, #4, #6, #7, #9, #10, #11. */
 837        count = 0;
 838        if (!head_match || !remote_match) {
 839                for (i = 1; i < o->head_idx; i++) {
 840                        if (stages[i] && stages[i] != o->df_conflict_entry) {
 841                                keep_entry(stages[i], o);
 842                                count++;
 843                                break;
 844                        }
 845                }
 846        }
 847#if DBRT_DEBUG
 848        else {
 849                fprintf(stderr, "read-tree: warning #16 detected\n");
 850                show_stage_entry(stderr, "head   ", stages[head_match]);
 851                show_stage_entry(stderr, "remote ", stages[remote_match]);
 852        }
 853#endif
 854        if (head) { count += keep_entry(head, o); }
 855        if (remote) { count += keep_entry(remote, o); }
 856        return count;
 857}
 858
 859/*
 860 * Two-way merge.
 861 *
 862 * The rule is to "carry forward" what is in the index without losing
 863 * information across a "fast forward", favoring a successful merge
 864 * over a merge failure when it makes sense.  For details of the
 865 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
 866 *
 867 */
 868int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
 869{
 870        struct cache_entry *current = src[0];
 871        struct cache_entry *oldtree = src[1];
 872        struct cache_entry *newtree = src[2];
 873
 874        if (o->merge_size != 2)
 875                return error("Cannot do a twoway merge of %d trees",
 876                             o->merge_size);
 877
 878        if (oldtree == o->df_conflict_entry)
 879                oldtree = NULL;
 880        if (newtree == o->df_conflict_entry)
 881                newtree = NULL;
 882
 883        if (current) {
 884                if ((!oldtree && !newtree) || /* 4 and 5 */
 885                    (!oldtree && newtree &&
 886                     same(current, newtree)) || /* 6 and 7 */
 887                    (oldtree && newtree &&
 888                     same(oldtree, newtree)) || /* 14 and 15 */
 889                    (oldtree && newtree &&
 890                     !same(oldtree, newtree) && /* 18 and 19 */
 891                     same(current, newtree))) {
 892                        return keep_entry(current, o);
 893                }
 894                else if (oldtree && !newtree && same(current, oldtree)) {
 895                        /* 10 or 11 */
 896                        return deleted_entry(oldtree, current, o);
 897                }
 898                else if (oldtree && newtree &&
 899                         same(current, oldtree) && !same(current, newtree)) {
 900                        /* 20 or 21 */
 901                        return merged_entry(newtree, current, o);
 902                }
 903                else {
 904                        /* all other failures */
 905                        if (oldtree)
 906                                return o->gently ? -1 : reject_merge(oldtree);
 907                        if (current)
 908                                return o->gently ? -1 : reject_merge(current);
 909                        if (newtree)
 910                                return o->gently ? -1 : reject_merge(newtree);
 911                        return -1;
 912                }
 913        }
 914        else if (newtree)
 915                return merged_entry(newtree, current, o);
 916        return deleted_entry(oldtree, current, o);
 917}
 918
 919/*
 920 * Bind merge.
 921 *
 922 * Keep the index entries at stage0, collapse stage1 but make sure
 923 * stage0 does not have anything there.
 924 */
 925int bind_merge(struct cache_entry **src,
 926                struct unpack_trees_options *o)
 927{
 928        struct cache_entry *old = src[0];
 929        struct cache_entry *a = src[1];
 930
 931        if (o->merge_size != 1)
 932                return error("Cannot do a bind merge of %d trees\n",
 933                             o->merge_size);
 934        if (a && old)
 935                return o->gently ? -1 :
 936                        error("Entry '%s' overlaps with '%s'.  Cannot bind.", a->name, old->name);
 937        if (!a)
 938                return keep_entry(old, o);
 939        else
 940                return merged_entry(a, NULL, o);
 941}
 942
 943/*
 944 * One-way merge.
 945 *
 946 * The rule is:
 947 * - take the stat information from stage0, take the data from stage1
 948 */
 949int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
 950{
 951        struct cache_entry *old = src[0];
 952        struct cache_entry *a = src[1];
 953
 954        if (o->merge_size != 1)
 955                return error("Cannot do a oneway merge of %d trees",
 956                             o->merge_size);
 957
 958        if (!a)
 959                return deleted_entry(old, old, o);
 960
 961        if (old && same(old, a)) {
 962                int update = 0;
 963                if (o->reset) {
 964                        struct stat st;
 965                        if (lstat(old->name, &st) ||
 966                            ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID))
 967                                update |= CE_UPDATE;
 968                }
 969                add_entry(o, old, update, 0);
 970                return 0;
 971        }
 972        return merged_entry(a, old, o);
 973}