unpack-trees.con commit read-tree --debug-unpack (ba655da)
   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
  37#define ERRORMSG(o,fld) \
  38        ( ((o) && (o)->msgs.fld) \
  39        ? ((o)->msgs.fld) \
  40        : (unpack_plumbing_errors.fld) )
  41
  42static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
  43        unsigned int set, unsigned int clear)
  44{
  45        unsigned int size = ce_size(ce);
  46        struct cache_entry *new = xmalloc(size);
  47
  48        clear |= CE_HASHED | CE_UNHASHED;
  49
  50        memcpy(new, ce, size);
  51        new->next = NULL;
  52        new->ce_flags = (new->ce_flags & ~clear) | set;
  53        add_index_entry(&o->result, new, ADD_CACHE_OK_TO_ADD|ADD_CACHE_OK_TO_REPLACE);
  54}
  55
  56/*
  57 * Unlink the last component and schedule the leading directories for
  58 * removal, such that empty directories get removed.
  59 */
  60static void unlink_entry(struct cache_entry *ce)
  61{
  62        if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
  63                return;
  64        if (unlink_or_warn(ce->name))
  65                return;
  66        schedule_dir_for_removal(ce->name, ce_namelen(ce));
  67}
  68
  69static struct checkout state;
  70static int check_updates(struct unpack_trees_options *o)
  71{
  72        unsigned cnt = 0, total = 0;
  73        struct progress *progress = NULL;
  74        struct index_state *index = &o->result;
  75        int i;
  76        int errs = 0;
  77
  78        if (o->update && o->verbose_update) {
  79                for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
  80                        struct cache_entry *ce = index->cache[cnt];
  81                        if (ce->ce_flags & (CE_UPDATE | CE_REMOVE))
  82                                total++;
  83                }
  84
  85                progress = start_progress_delay("Checking out files",
  86                                                total, 50, 1);
  87                cnt = 0;
  88        }
  89
  90        if (o->update)
  91                git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
  92        for (i = 0; i < index->cache_nr; i++) {
  93                struct cache_entry *ce = index->cache[i];
  94
  95                if (ce->ce_flags & CE_REMOVE) {
  96                        display_progress(progress, ++cnt);
  97                        if (o->update)
  98                                unlink_entry(ce);
  99                }
 100        }
 101        remove_marked_cache_entries(&o->result);
 102        remove_scheduled_dirs();
 103
 104        for (i = 0; i < index->cache_nr; i++) {
 105                struct cache_entry *ce = index->cache[i];
 106
 107                if (ce->ce_flags & CE_UPDATE) {
 108                        display_progress(progress, ++cnt);
 109                        ce->ce_flags &= ~CE_UPDATE;
 110                        if (o->update) {
 111                                errs |= checkout_entry(ce, &state, NULL);
 112                        }
 113                }
 114        }
 115        stop_progress(&progress);
 116        if (o->update)
 117                git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
 118        return errs != 0;
 119}
 120
 121static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
 122{
 123        int ret = o->fn(src, o);
 124        if (ret > 0)
 125                ret = 0;
 126        return ret;
 127}
 128
 129static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
 130{
 131        ce->ce_flags |= CE_UNPACKED;
 132
 133        if (o->cache_bottom < o->src_index->cache_nr &&
 134            o->src_index->cache[o->cache_bottom] == ce) {
 135                int bottom = o->cache_bottom;
 136                while (bottom < o->src_index->cache_nr &&
 137                       o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
 138                        bottom++;
 139                o->cache_bottom = bottom;
 140        }
 141}
 142
 143static void mark_all_ce_unused(struct index_state *index)
 144{
 145        int i;
 146        for (i = 0; i < index->cache_nr; i++)
 147                index->cache[i]->ce_flags &= ~CE_UNPACKED;
 148}
 149
 150static int locate_in_src_index(struct cache_entry *ce,
 151                               struct unpack_trees_options *o)
 152{
 153        struct index_state *index = o->src_index;
 154        int len = ce_namelen(ce);
 155        int pos = index_name_pos(index, ce->name, len);
 156        if (pos < 0)
 157                pos = -1 - pos;
 158        return pos;
 159}
 160
 161/*
 162 * We call unpack_index_entry() with an unmerged cache entry
 163 * only in diff-index, and it wants a single callback.  Skip
 164 * the other unmerged entry with the same name.
 165 */
 166static void mark_ce_used_same_name(struct cache_entry *ce,
 167                                   struct unpack_trees_options *o)
 168{
 169        struct index_state *index = o->src_index;
 170        int len = ce_namelen(ce);
 171        int pos;
 172
 173        for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
 174                struct cache_entry *next = index->cache[pos];
 175                if (len != ce_namelen(next) ||
 176                    memcmp(ce->name, next->name, len))
 177                        break;
 178                mark_ce_used(next, o);
 179        }
 180}
 181
 182static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
 183{
 184        const struct index_state *index = o->src_index;
 185        int pos = o->cache_bottom;
 186
 187        while (pos < index->cache_nr) {
 188                struct cache_entry *ce = index->cache[pos];
 189                if (!(ce->ce_flags & CE_UNPACKED))
 190                        return ce;
 191                pos++;
 192        }
 193        return NULL;
 194}
 195
 196static void add_same_unmerged(struct cache_entry *ce,
 197                              struct unpack_trees_options *o)
 198{
 199        struct index_state *index = o->src_index;
 200        int len = ce_namelen(ce);
 201        int pos = index_name_pos(index, ce->name, len);
 202
 203        if (0 <= pos)
 204                die("programming error in a caller of mark_ce_used_same_name");
 205        for (pos = -pos - 1; pos < index->cache_nr; pos++) {
 206                struct cache_entry *next = index->cache[pos];
 207                if (len != ce_namelen(next) ||
 208                    memcmp(ce->name, next->name, len))
 209                        break;
 210                add_entry(o, next, 0, 0);
 211                mark_ce_used(next, o);
 212        }
 213}
 214
 215static int unpack_index_entry(struct cache_entry *ce,
 216                              struct unpack_trees_options *o)
 217{
 218        struct cache_entry *src[5] = { ce, NULL, };
 219        int ret;
 220
 221        mark_ce_used(ce, o);
 222        if (ce_stage(ce)) {
 223                if (o->skip_unmerged) {
 224                        add_entry(o, ce, 0, 0);
 225                        return 0;
 226                }
 227        }
 228        ret = call_unpack_fn(src, o);
 229        if (ce_stage(ce))
 230                mark_ce_used_same_name(ce, o);
 231        return ret;
 232}
 233
 234static int find_cache_pos(struct traverse_info *, const struct name_entry *);
 235
 236static void restore_cache_bottom(struct traverse_info *info, int bottom)
 237{
 238        struct unpack_trees_options *o = info->data;
 239
 240        if (o->diff_index_cached)
 241                return;
 242        o->cache_bottom = bottom;
 243}
 244
 245static int switch_cache_bottom(struct traverse_info *info)
 246{
 247        struct unpack_trees_options *o = info->data;
 248        int ret, pos;
 249
 250        if (o->diff_index_cached)
 251                return 0;
 252        ret = o->cache_bottom;
 253        pos = find_cache_pos(info->prev, &info->name);
 254
 255        if (pos < -1)
 256                o->cache_bottom = -2 - pos;
 257        else if (pos < 0)
 258                o->cache_bottom = o->src_index->cache_nr;
 259        return ret;
 260}
 261
 262static int traverse_trees_recursive(int n, unsigned long dirmask, unsigned long df_conflicts, struct name_entry *names, struct traverse_info *info)
 263{
 264        int i, ret, bottom;
 265        struct tree_desc t[MAX_UNPACK_TREES];
 266        struct traverse_info newinfo;
 267        struct name_entry *p;
 268
 269        p = names;
 270        while (!p->mode)
 271                p++;
 272
 273        newinfo = *info;
 274        newinfo.prev = info;
 275        newinfo.name = *p;
 276        newinfo.pathlen += tree_entry_len(p->path, p->sha1) + 1;
 277        newinfo.conflicts |= df_conflicts;
 278
 279        for (i = 0; i < n; i++, dirmask >>= 1) {
 280                const unsigned char *sha1 = NULL;
 281                if (dirmask & 1)
 282                        sha1 = names[i].sha1;
 283                fill_tree_descriptor(t+i, sha1);
 284        }
 285
 286        bottom = switch_cache_bottom(&newinfo);
 287        ret = traverse_trees(n, t, &newinfo);
 288        restore_cache_bottom(&newinfo, bottom);
 289        return ret;
 290}
 291
 292/*
 293 * Compare the traverse-path to the cache entry without actually
 294 * having to generate the textual representation of the traverse
 295 * path.
 296 *
 297 * NOTE! This *only* compares up to the size of the traverse path
 298 * itself - the caller needs to do the final check for the cache
 299 * entry having more data at the end!
 300 */
 301static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 302{
 303        int len, pathlen, ce_len;
 304        const char *ce_name;
 305
 306        if (info->prev) {
 307                int cmp = do_compare_entry(ce, info->prev, &info->name);
 308                if (cmp)
 309                        return cmp;
 310        }
 311        pathlen = info->pathlen;
 312        ce_len = ce_namelen(ce);
 313
 314        /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 315        if (ce_len < pathlen)
 316                return -1;
 317
 318        ce_len -= pathlen;
 319        ce_name = ce->name + pathlen;
 320
 321        len = tree_entry_len(n->path, n->sha1);
 322        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 323}
 324
 325static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 326{
 327        int cmp = do_compare_entry(ce, info, n);
 328        if (cmp)
 329                return cmp;
 330
 331        /*
 332         * Even if the beginning compared identically, the ce should
 333         * compare as bigger than a directory leading up to it!
 334         */
 335        return ce_namelen(ce) > traverse_path_len(info, n);
 336}
 337
 338static int ce_in_traverse_path(const struct cache_entry *ce,
 339                               const struct traverse_info *info)
 340{
 341        if (!info->prev)
 342                return 1;
 343        if (do_compare_entry(ce, info->prev, &info->name))
 344                return 0;
 345        /*
 346         * If ce (blob) is the same name as the path (which is a tree
 347         * we will be descending into), it won't be inside it.
 348         */
 349        return (info->pathlen < ce_namelen(ce));
 350}
 351
 352static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
 353{
 354        int len = traverse_path_len(info, n);
 355        struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
 356
 357        ce->ce_mode = create_ce_mode(n->mode);
 358        ce->ce_flags = create_ce_flags(len, stage);
 359        hashcpy(ce->sha1, n->sha1);
 360        make_traverse_path(ce->name, info, n);
 361
 362        return ce;
 363}
 364
 365static int unpack_nondirectories(int n, unsigned long mask,
 366                                 unsigned long dirmask,
 367                                 struct cache_entry **src,
 368                                 const struct name_entry *names,
 369                                 const struct traverse_info *info)
 370{
 371        int i;
 372        struct unpack_trees_options *o = info->data;
 373        unsigned long conflicts;
 374
 375        /* Do we have *only* directories? Nothing to do */
 376        if (mask == dirmask && !src[0])
 377                return 0;
 378
 379        conflicts = info->conflicts;
 380        if (o->merge)
 381                conflicts >>= 1;
 382        conflicts |= dirmask;
 383
 384        /*
 385         * Ok, we've filled in up to any potential index entry in src[0],
 386         * now do the rest.
 387         */
 388        for (i = 0; i < n; i++) {
 389                int stage;
 390                unsigned int bit = 1ul << i;
 391                if (conflicts & bit) {
 392                        src[i + o->merge] = o->df_conflict_entry;
 393                        continue;
 394                }
 395                if (!(mask & bit))
 396                        continue;
 397                if (!o->merge)
 398                        stage = 0;
 399                else if (i + 1 < o->head_idx)
 400                        stage = 1;
 401                else if (i + 1 > o->head_idx)
 402                        stage = 3;
 403                else
 404                        stage = 2;
 405                src[i + o->merge] = create_ce_entry(info, names + i, stage);
 406        }
 407
 408        if (o->merge)
 409                return call_unpack_fn(src, o);
 410
 411        for (i = 0; i < n; i++)
 412                if (src[i] && src[i] != o->df_conflict_entry)
 413                        add_entry(o, src[i], 0, 0);
 414        return 0;
 415}
 416
 417static int unpack_failed(struct unpack_trees_options *o, const char *message)
 418{
 419        discard_index(&o->result);
 420        if (!o->gently) {
 421                if (message)
 422                        return error("%s", message);
 423                return -1;
 424        }
 425        return -1;
 426}
 427
 428/* NEEDSWORK: give this a better name and share with tree-walk.c */
 429static int name_compare(const char *a, int a_len,
 430                        const char *b, int b_len)
 431{
 432        int len = (a_len < b_len) ? a_len : b_len;
 433        int cmp = memcmp(a, b, len);
 434        if (cmp)
 435                return cmp;
 436        return (a_len - b_len);
 437}
 438
 439/*
 440 * The tree traversal is looking at name p.  If we have a matching entry,
 441 * return it.  If name p is a directory in the index, do not return
 442 * anything, as we will want to match it when the traversal descends into
 443 * the directory.
 444 */
 445static int find_cache_pos(struct traverse_info *info,
 446                          const struct name_entry *p)
 447{
 448        int pos;
 449        struct unpack_trees_options *o = info->data;
 450        struct index_state *index = o->src_index;
 451        int pfxlen = info->pathlen;
 452        int p_len = tree_entry_len(p->path, p->sha1);
 453
 454        for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
 455                struct cache_entry *ce = index->cache[pos];
 456                const char *ce_name, *ce_slash;
 457                int cmp, ce_len;
 458
 459                if (!ce_in_traverse_path(ce, info))
 460                        continue;
 461                if (ce->ce_flags & CE_UNPACKED)
 462                        continue;
 463                ce_name = ce->name + pfxlen;
 464                ce_slash = strchr(ce_name, '/');
 465                if (ce_slash)
 466                        ce_len = ce_slash - ce_name;
 467                else
 468                        ce_len = ce_namelen(ce) - pfxlen;
 469                cmp = name_compare(p->path, p_len, ce_name, ce_len);
 470                /*
 471                 * Exact match; if we have a directory we need to
 472                 * delay returning it.
 473                 */
 474                if (!cmp)
 475                        return ce_slash ? -2 - pos : pos;
 476                if (0 < cmp)
 477                        continue; /* keep looking */
 478                /*
 479                 * ce_name sorts after p->path; could it be that we
 480                 * have files under p->path directory in the index?
 481                 * E.g.  ce_name == "t-i", and p->path == "t"; we may
 482                 * have "t/a" in the index.
 483                 */
 484                if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
 485                    ce_name[p_len] < '/')
 486                        continue; /* keep looking */
 487                break;
 488        }
 489        return -1;
 490}
 491
 492static struct cache_entry *find_cache_entry(struct traverse_info *info,
 493                                            const struct name_entry *p)
 494{
 495        int pos = find_cache_pos(info, p);
 496        struct unpack_trees_options *o = info->data;
 497
 498        if (0 <= pos)
 499                return o->src_index->cache[pos];
 500        else
 501                return NULL;
 502}
 503
 504static void debug_path(struct traverse_info *info)
 505{
 506        if (info->prev) {
 507                debug_path(info->prev);
 508                if (*info->prev->name.path)
 509                        putchar('/');
 510        }
 511        printf("%s", info->name.path);
 512}
 513
 514static void debug_name_entry(int i, struct name_entry *n)
 515{
 516        printf("ent#%d %06o %s\n", i,
 517               n->path ? n->mode : 0,
 518               n->path ? n->path : "(missing)");
 519}
 520
 521static void debug_unpack_callback(int n,
 522                                  unsigned long mask,
 523                                  unsigned long dirmask,
 524                                  struct name_entry *names,
 525                                  struct traverse_info *info)
 526{
 527        int i;
 528        printf("* unpack mask %lu, dirmask %lu, cnt %d ",
 529               mask, dirmask, n);
 530        debug_path(info);
 531        putchar('\n');
 532        for (i = 0; i < n; i++)
 533                debug_name_entry(i, names + i);
 534}
 535
 536static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
 537{
 538        struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 539        struct unpack_trees_options *o = info->data;
 540        const struct name_entry *p = names;
 541
 542        /* Find first entry with a real name (we could use "mask" too) */
 543        while (!p->mode)
 544                p++;
 545
 546        if (o->debug_unpack)
 547                debug_unpack_callback(n, mask, dirmask, names, info);
 548
 549        /* Are we supposed to look at the index too? */
 550        if (o->merge) {
 551                while (1) {
 552                        int cmp;
 553                        struct cache_entry *ce;
 554
 555                        if (o->diff_index_cached)
 556                                ce = next_cache_entry(o);
 557                        else
 558                                ce = find_cache_entry(info, p);
 559
 560                        if (!ce)
 561                                break;
 562                        cmp = compare_entry(ce, info, p);
 563                        if (cmp < 0) {
 564                                if (unpack_index_entry(ce, o) < 0)
 565                                        return unpack_failed(o, NULL);
 566                                continue;
 567                        }
 568                        if (!cmp) {
 569                                if (ce_stage(ce)) {
 570                                        /*
 571                                         * If we skip unmerged index
 572                                         * entries, we'll skip this
 573                                         * entry *and* the tree
 574                                         * entries associated with it!
 575                                         */
 576                                        if (o->skip_unmerged) {
 577                                                add_same_unmerged(ce, o);
 578                                                return mask;
 579                                        }
 580                                }
 581                                src[0] = ce;
 582                        }
 583                        break;
 584                }
 585        }
 586
 587        if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
 588                return -1;
 589
 590        if (src[0]) {
 591                if (ce_stage(src[0]))
 592                        mark_ce_used_same_name(src[0], o);
 593                else
 594                        mark_ce_used(src[0], o);
 595        }
 596
 597        /* Now handle any directories.. */
 598        if (dirmask) {
 599                unsigned long conflicts = mask & ~dirmask;
 600                if (o->merge) {
 601                        conflicts <<= 1;
 602                        if (src[0])
 603                                conflicts |= 1;
 604                }
 605
 606                /* special case: "diff-index --cached" looking at a tree */
 607                if (o->diff_index_cached &&
 608                    n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
 609                        int matches;
 610                        matches = cache_tree_matches_traversal(o->src_index->cache_tree,
 611                                                               names, info);
 612                        /*
 613                         * Everything under the name matches; skip the
 614                         * entire hierarchy.  diff_index_cached codepath
 615                         * special cases D/F conflicts in such a way that
 616                         * it does not do any look-ahead, so this is safe.
 617                         */
 618                        if (matches) {
 619                                o->cache_bottom += matches;
 620                                return mask;
 621                        }
 622                }
 623
 624                if (traverse_trees_recursive(n, dirmask, conflicts,
 625                                             names, info) < 0)
 626                        return -1;
 627                return mask;
 628        }
 629
 630        return mask;
 631}
 632
 633/*
 634 * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
 635 * resulting index, -2 on failure to reflect the changes to the work tree.
 636 */
 637int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
 638{
 639        int ret;
 640        static struct cache_entry *dfc;
 641
 642        if (len > MAX_UNPACK_TREES)
 643                die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
 644        memset(&state, 0, sizeof(state));
 645        state.base_dir = "";
 646        state.force = 1;
 647        state.quiet = 1;
 648        state.refresh_cache = 1;
 649
 650        memset(&o->result, 0, sizeof(o->result));
 651        o->result.initialized = 1;
 652        o->result.timestamp.sec = o->src_index->timestamp.sec;
 653        o->result.timestamp.nsec = o->src_index->timestamp.nsec;
 654        o->merge_size = len;
 655        mark_all_ce_unused(o->src_index);
 656
 657        if (!dfc)
 658                dfc = xcalloc(1, cache_entry_size(0));
 659        o->df_conflict_entry = dfc;
 660
 661        if (len) {
 662                const char *prefix = o->prefix ? o->prefix : "";
 663                struct traverse_info info;
 664
 665                setup_traverse_info(&info, prefix);
 666                info.fn = unpack_callback;
 667                info.data = o;
 668
 669                if (o->prefix) {
 670                        /*
 671                         * Unpack existing index entries that sort before the
 672                         * prefix the tree is spliced into.  Note that o->merge
 673                         * is always true in this case.
 674                         */
 675                        while (1) {
 676                                struct cache_entry *ce = next_cache_entry(o);
 677                                if (!ce)
 678                                        break;
 679                                if (ce_in_traverse_path(ce, &info))
 680                                        break;
 681                                if (unpack_index_entry(ce, o) < 0)
 682                                        goto return_failed;
 683                        }
 684                }
 685
 686                if (traverse_trees(len, t, &info) < 0)
 687                        goto return_failed;
 688        }
 689
 690        /* Any left-over entries in the index? */
 691        if (o->merge) {
 692                while (1) {
 693                        struct cache_entry *ce = next_cache_entry(o);
 694                        if (!ce)
 695                                break;
 696                        if (unpack_index_entry(ce, o) < 0)
 697                                goto return_failed;
 698                }
 699        }
 700        mark_all_ce_unused(o->src_index);
 701
 702        if (o->trivial_merges_only && o->nontrivial_merge)
 703                return unpack_failed(o, "Merge requires file-level merging");
 704
 705        o->src_index = NULL;
 706        ret = check_updates(o) ? (-2) : 0;
 707        if (o->dst_index)
 708                *o->dst_index = o->result;
 709        return ret;
 710
 711return_failed:
 712        mark_all_ce_unused(o->src_index);
 713        return unpack_failed(o, NULL);
 714}
 715
 716/* Here come the merge functions */
 717
 718static int reject_merge(struct cache_entry *ce, struct unpack_trees_options *o)
 719{
 720        return error(ERRORMSG(o, would_overwrite), ce->name);
 721}
 722
 723static int same(struct cache_entry *a, struct cache_entry *b)
 724{
 725        if (!!a != !!b)
 726                return 0;
 727        if (!a && !b)
 728                return 1;
 729        return a->ce_mode == b->ce_mode &&
 730               !hashcmp(a->sha1, b->sha1);
 731}
 732
 733
 734/*
 735 * When a CE gets turned into an unmerged entry, we
 736 * want it to be up-to-date
 737 */
 738static int verify_uptodate(struct cache_entry *ce,
 739                struct unpack_trees_options *o)
 740{
 741        struct stat st;
 742
 743        if (o->index_only || o->reset || ce_uptodate(ce))
 744                return 0;
 745
 746        if (!lstat(ce->name, &st)) {
 747                unsigned changed = ie_match_stat(o->src_index, ce, &st, CE_MATCH_IGNORE_VALID);
 748                if (!changed)
 749                        return 0;
 750                /*
 751                 * NEEDSWORK: the current default policy is to allow
 752                 * submodule to be out of sync wrt the supermodule
 753                 * index.  This needs to be tightened later for
 754                 * submodules that are marked to be automatically
 755                 * checked out.
 756                 */
 757                if (S_ISGITLINK(ce->ce_mode))
 758                        return 0;
 759                errno = 0;
 760        }
 761        if (errno == ENOENT)
 762                return 0;
 763        return o->gently ? -1 :
 764                error(ERRORMSG(o, not_uptodate_file), ce->name);
 765}
 766
 767static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
 768{
 769        if (ce)
 770                cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
 771}
 772
 773/*
 774 * Check that checking out ce->sha1 in subdir ce->name is not
 775 * going to overwrite any working files.
 776 *
 777 * Currently, git does not checkout subprojects during a superproject
 778 * checkout, so it is not going to overwrite anything.
 779 */
 780static int verify_clean_submodule(struct cache_entry *ce, const char *action,
 781                                      struct unpack_trees_options *o)
 782{
 783        return 0;
 784}
 785
 786static int verify_clean_subdirectory(struct cache_entry *ce, const char *action,
 787                                      struct unpack_trees_options *o)
 788{
 789        /*
 790         * we are about to extract "ce->name"; we would not want to lose
 791         * anything in the existing directory there.
 792         */
 793        int namelen;
 794        int i;
 795        struct dir_struct d;
 796        char *pathbuf;
 797        int cnt = 0;
 798        unsigned char sha1[20];
 799
 800        if (S_ISGITLINK(ce->ce_mode) &&
 801            resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
 802                /* If we are not going to update the submodule, then
 803                 * we don't care.
 804                 */
 805                if (!hashcmp(sha1, ce->sha1))
 806                        return 0;
 807                return verify_clean_submodule(ce, action, o);
 808        }
 809
 810        /*
 811         * First let's make sure we do not have a local modification
 812         * in that directory.
 813         */
 814        namelen = strlen(ce->name);
 815        for (i = locate_in_src_index(ce, o);
 816             i < o->src_index->cache_nr;
 817             i++) {
 818                struct cache_entry *ce2 = o->src_index->cache[i];
 819                int len = ce_namelen(ce2);
 820                if (len < namelen ||
 821                    strncmp(ce->name, ce2->name, namelen) ||
 822                    ce2->name[namelen] != '/')
 823                        break;
 824                /*
 825                 * ce2->name is an entry in the subdirectory to be
 826                 * removed.
 827                 */
 828                if (!ce_stage(ce2)) {
 829                        if (verify_uptodate(ce2, o))
 830                                return -1;
 831                        add_entry(o, ce2, CE_REMOVE, 0);
 832                        mark_ce_used(ce2, o);
 833                }
 834                cnt++;
 835        }
 836
 837        /*
 838         * Then we need to make sure that we do not lose a locally
 839         * present file that is not ignored.
 840         */
 841        pathbuf = xmalloc(namelen + 2);
 842        memcpy(pathbuf, ce->name, namelen);
 843        strcpy(pathbuf+namelen, "/");
 844
 845        memset(&d, 0, sizeof(d));
 846        if (o->dir)
 847                d.exclude_per_dir = o->dir->exclude_per_dir;
 848        i = read_directory(&d, pathbuf, namelen+1, NULL);
 849        if (i)
 850                return o->gently ? -1 :
 851                        error(ERRORMSG(o, not_uptodate_dir), ce->name);
 852        free(pathbuf);
 853        return cnt;
 854}
 855
 856/*
 857 * This gets called when there was no index entry for the tree entry 'dst',
 858 * but we found a file in the working tree that 'lstat()' said was fine,
 859 * and we're on a case-insensitive filesystem.
 860 *
 861 * See if we can find a case-insensitive match in the index that also
 862 * matches the stat information, and assume it's that other file!
 863 */
 864static int icase_exists(struct unpack_trees_options *o, struct cache_entry *dst, struct stat *st)
 865{
 866        struct cache_entry *src;
 867
 868        src = index_name_exists(o->src_index, dst->name, ce_namelen(dst), 1);
 869        return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID);
 870}
 871
 872/*
 873 * We do not want to remove or overwrite a working tree file that
 874 * is not tracked, unless it is ignored.
 875 */
 876static int verify_absent(struct cache_entry *ce, const char *action,
 877                         struct unpack_trees_options *o)
 878{
 879        struct stat st;
 880
 881        if (o->index_only || o->reset || !o->update)
 882                return 0;
 883
 884        if (has_symlink_or_noent_leading_path(ce->name, ce_namelen(ce)))
 885                return 0;
 886
 887        if (!lstat(ce->name, &st)) {
 888                int dtype = ce_to_dtype(ce);
 889                struct cache_entry *result;
 890
 891                /*
 892                 * It may be that the 'lstat()' succeeded even though
 893                 * target 'ce' was absent, because there is an old
 894                 * entry that is different only in case..
 895                 *
 896                 * Ignore that lstat() if it matches.
 897                 */
 898                if (ignore_case && icase_exists(o, ce, &st))
 899                        return 0;
 900
 901                if (o->dir && excluded(o->dir, ce->name, &dtype))
 902                        /*
 903                         * ce->name is explicitly excluded, so it is Ok to
 904                         * overwrite it.
 905                         */
 906                        return 0;
 907                if (S_ISDIR(st.st_mode)) {
 908                        /*
 909                         * We are checking out path "foo" and
 910                         * found "foo/." in the working tree.
 911                         * This is tricky -- if we have modified
 912                         * files that are in "foo/" we would lose
 913                         * them.
 914                         */
 915                        if (verify_clean_subdirectory(ce, action, o) < 0)
 916                                return -1;
 917                        return 0;
 918                }
 919
 920                /*
 921                 * The previous round may already have decided to
 922                 * delete this path, which is in a subdirectory that
 923                 * is being replaced with a blob.
 924                 */
 925                result = index_name_exists(&o->result, ce->name, ce_namelen(ce), 0);
 926                if (result) {
 927                        if (result->ce_flags & CE_REMOVE)
 928                                return 0;
 929                }
 930
 931                return o->gently ? -1 :
 932                        error(ERRORMSG(o, would_lose_untracked), ce->name, action);
 933        }
 934        return 0;
 935}
 936
 937static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
 938                struct unpack_trees_options *o)
 939{
 940        int update = CE_UPDATE;
 941
 942        if (old) {
 943                /*
 944                 * See if we can re-use the old CE directly?
 945                 * That way we get the uptodate stat info.
 946                 *
 947                 * This also removes the UPDATE flag on a match; otherwise
 948                 * we will end up overwriting local changes in the work tree.
 949                 */
 950                if (same(old, merge)) {
 951                        copy_cache_entry(merge, old);
 952                        update = 0;
 953                } else {
 954                        if (verify_uptodate(old, o))
 955                                return -1;
 956                        invalidate_ce_path(old, o);
 957                }
 958        }
 959        else {
 960                if (verify_absent(merge, "overwritten", o))
 961                        return -1;
 962                invalidate_ce_path(merge, o);
 963        }
 964
 965        add_entry(o, merge, update, CE_STAGEMASK);
 966        return 1;
 967}
 968
 969static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
 970                struct unpack_trees_options *o)
 971{
 972        /* Did it exist in the index? */
 973        if (!old) {
 974                if (verify_absent(ce, "removed", o))
 975                        return -1;
 976                return 0;
 977        }
 978        if (verify_uptodate(old, o))
 979                return -1;
 980        add_entry(o, ce, CE_REMOVE, 0);
 981        invalidate_ce_path(ce, o);
 982        return 1;
 983}
 984
 985static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
 986{
 987        add_entry(o, ce, 0, 0);
 988        return 1;
 989}
 990
 991#if DBRT_DEBUG
 992static void show_stage_entry(FILE *o,
 993                             const char *label, const struct cache_entry *ce)
 994{
 995        if (!ce)
 996                fprintf(o, "%s (missing)\n", label);
 997        else
 998                fprintf(o, "%s%06o %s %d\t%s\n",
 999                        label,
1000                        ce->ce_mode,
1001                        sha1_to_hex(ce->sha1),
1002                        ce_stage(ce),
1003                        ce->name);
1004}
1005#endif
1006
1007int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
1008{
1009        struct cache_entry *index;
1010        struct cache_entry *head;
1011        struct cache_entry *remote = stages[o->head_idx + 1];
1012        int count;
1013        int head_match = 0;
1014        int remote_match = 0;
1015
1016        int df_conflict_head = 0;
1017        int df_conflict_remote = 0;
1018
1019        int any_anc_missing = 0;
1020        int no_anc_exists = 1;
1021        int i;
1022
1023        for (i = 1; i < o->head_idx; i++) {
1024                if (!stages[i] || stages[i] == o->df_conflict_entry)
1025                        any_anc_missing = 1;
1026                else
1027                        no_anc_exists = 0;
1028        }
1029
1030        index = stages[0];
1031        head = stages[o->head_idx];
1032
1033        if (head == o->df_conflict_entry) {
1034                df_conflict_head = 1;
1035                head = NULL;
1036        }
1037
1038        if (remote == o->df_conflict_entry) {
1039                df_conflict_remote = 1;
1040                remote = NULL;
1041        }
1042
1043        /*
1044         * First, if there's a #16 situation, note that to prevent #13
1045         * and #14.
1046         */
1047        if (!same(remote, head)) {
1048                for (i = 1; i < o->head_idx; i++) {
1049                        if (same(stages[i], head)) {
1050                                head_match = i;
1051                        }
1052                        if (same(stages[i], remote)) {
1053                                remote_match = i;
1054                        }
1055                }
1056        }
1057
1058        /*
1059         * We start with cases where the index is allowed to match
1060         * something other than the head: #14(ALT) and #2ALT, where it
1061         * is permitted to match the result instead.
1062         */
1063        /* #14, #14ALT, #2ALT */
1064        if (remote && !df_conflict_head && head_match && !remote_match) {
1065                if (index && !same(index, remote) && !same(index, head))
1066                        return o->gently ? -1 : reject_merge(index, o);
1067                return merged_entry(remote, index, o);
1068        }
1069        /*
1070         * If we have an entry in the index cache, then we want to
1071         * make sure that it matches head.
1072         */
1073        if (index && !same(index, head))
1074                return o->gently ? -1 : reject_merge(index, o);
1075
1076        if (head) {
1077                /* #5ALT, #15 */
1078                if (same(head, remote))
1079                        return merged_entry(head, index, o);
1080                /* #13, #3ALT */
1081                if (!df_conflict_remote && remote_match && !head_match)
1082                        return merged_entry(head, index, o);
1083        }
1084
1085        /* #1 */
1086        if (!head && !remote && any_anc_missing)
1087                return 0;
1088
1089        /*
1090         * Under the "aggressive" rule, we resolve mostly trivial
1091         * cases that we historically had git-merge-one-file resolve.
1092         */
1093        if (o->aggressive) {
1094                int head_deleted = !head;
1095                int remote_deleted = !remote;
1096                struct cache_entry *ce = NULL;
1097
1098                if (index)
1099                        ce = index;
1100                else if (head)
1101                        ce = head;
1102                else if (remote)
1103                        ce = remote;
1104                else {
1105                        for (i = 1; i < o->head_idx; i++) {
1106                                if (stages[i] && stages[i] != o->df_conflict_entry) {
1107                                        ce = stages[i];
1108                                        break;
1109                                }
1110                        }
1111                }
1112
1113                /*
1114                 * Deleted in both.
1115                 * Deleted in one and unchanged in the other.
1116                 */
1117                if ((head_deleted && remote_deleted) ||
1118                    (head_deleted && remote && remote_match) ||
1119                    (remote_deleted && head && head_match)) {
1120                        if (index)
1121                                return deleted_entry(index, index, o);
1122                        if (ce && !head_deleted) {
1123                                if (verify_absent(ce, "removed", o))
1124                                        return -1;
1125                        }
1126                        return 0;
1127                }
1128                /*
1129                 * Added in both, identically.
1130                 */
1131                if (no_anc_exists && head && remote && same(head, remote))
1132                        return merged_entry(head, index, o);
1133
1134        }
1135
1136        /* Below are "no merge" cases, which require that the index be
1137         * up-to-date to avoid the files getting overwritten with
1138         * conflict resolution files.
1139         */
1140        if (index) {
1141                if (verify_uptodate(index, o))
1142                        return -1;
1143        }
1144
1145        o->nontrivial_merge = 1;
1146
1147        /* #2, #3, #4, #6, #7, #9, #10, #11. */
1148        count = 0;
1149        if (!head_match || !remote_match) {
1150                for (i = 1; i < o->head_idx; i++) {
1151                        if (stages[i] && stages[i] != o->df_conflict_entry) {
1152                                keep_entry(stages[i], o);
1153                                count++;
1154                                break;
1155                        }
1156                }
1157        }
1158#if DBRT_DEBUG
1159        else {
1160                fprintf(stderr, "read-tree: warning #16 detected\n");
1161                show_stage_entry(stderr, "head   ", stages[head_match]);
1162                show_stage_entry(stderr, "remote ", stages[remote_match]);
1163        }
1164#endif
1165        if (head) { count += keep_entry(head, o); }
1166        if (remote) { count += keep_entry(remote, o); }
1167        return count;
1168}
1169
1170/*
1171 * Two-way merge.
1172 *
1173 * The rule is to "carry forward" what is in the index without losing
1174 * information across a "fast-forward", favoring a successful merge
1175 * over a merge failure when it makes sense.  For details of the
1176 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
1177 *
1178 */
1179int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1180{
1181        struct cache_entry *current = src[0];
1182        struct cache_entry *oldtree = src[1];
1183        struct cache_entry *newtree = src[2];
1184
1185        if (o->merge_size != 2)
1186                return error("Cannot do a twoway merge of %d trees",
1187                             o->merge_size);
1188
1189        if (oldtree == o->df_conflict_entry)
1190                oldtree = NULL;
1191        if (newtree == o->df_conflict_entry)
1192                newtree = NULL;
1193
1194        if (current) {
1195                if ((!oldtree && !newtree) || /* 4 and 5 */
1196                    (!oldtree && newtree &&
1197                     same(current, newtree)) || /* 6 and 7 */
1198                    (oldtree && newtree &&
1199                     same(oldtree, newtree)) || /* 14 and 15 */
1200                    (oldtree && newtree &&
1201                     !same(oldtree, newtree) && /* 18 and 19 */
1202                     same(current, newtree))) {
1203                        return keep_entry(current, o);
1204                }
1205                else if (oldtree && !newtree && same(current, oldtree)) {
1206                        /* 10 or 11 */
1207                        return deleted_entry(oldtree, current, o);
1208                }
1209                else if (oldtree && newtree &&
1210                         same(current, oldtree) && !same(current, newtree)) {
1211                        /* 20 or 21 */
1212                        return merged_entry(newtree, current, o);
1213                }
1214                else {
1215                        /* all other failures */
1216                        if (oldtree)
1217                                return o->gently ? -1 : reject_merge(oldtree, o);
1218                        if (current)
1219                                return o->gently ? -1 : reject_merge(current, o);
1220                        if (newtree)
1221                                return o->gently ? -1 : reject_merge(newtree, o);
1222                        return -1;
1223                }
1224        }
1225        else if (newtree) {
1226                if (oldtree && !o->initial_checkout) {
1227                        /*
1228                         * deletion of the path was staged;
1229                         */
1230                        if (same(oldtree, newtree))
1231                                return 1;
1232                        return reject_merge(oldtree, o);
1233                }
1234                return merged_entry(newtree, current, o);
1235        }
1236        return deleted_entry(oldtree, current, o);
1237}
1238
1239/*
1240 * Bind merge.
1241 *
1242 * Keep the index entries at stage0, collapse stage1 but make sure
1243 * stage0 does not have anything there.
1244 */
1245int bind_merge(struct cache_entry **src,
1246                struct unpack_trees_options *o)
1247{
1248        struct cache_entry *old = src[0];
1249        struct cache_entry *a = src[1];
1250
1251        if (o->merge_size != 1)
1252                return error("Cannot do a bind merge of %d trees\n",
1253                             o->merge_size);
1254        if (a && old)
1255                return o->gently ? -1 :
1256                        error(ERRORMSG(o, bind_overlap), a->name, old->name);
1257        if (!a)
1258                return keep_entry(old, o);
1259        else
1260                return merged_entry(a, NULL, o);
1261}
1262
1263/*
1264 * One-way merge.
1265 *
1266 * The rule is:
1267 * - take the stat information from stage0, take the data from stage1
1268 */
1269int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1270{
1271        struct cache_entry *old = src[0];
1272        struct cache_entry *a = src[1];
1273
1274        if (o->merge_size != 1)
1275                return error("Cannot do a oneway merge of %d trees",
1276                             o->merge_size);
1277
1278        if (!a || a == o->df_conflict_entry)
1279                return deleted_entry(old, old, o);
1280
1281        if (old && same(old, a)) {
1282                int update = 0;
1283                if (o->reset && !ce_uptodate(old)) {
1284                        struct stat st;
1285                        if (lstat(old->name, &st) ||
1286                            ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID))
1287                                update |= CE_UPDATE;
1288                }
1289                add_entry(o, old, update, 0);
1290                return 0;
1291        }
1292        return merged_entry(a, old, o);
1293}