unpack-trees.con commit Merge branch 'lt/commit-tree-guess-utf-8' (ae80b5a)
   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" and "git merge" replaces
  17 * them using setup_unpack_trees_porcelain(), for example.
  18 */
  19static const char *unpack_plumbing_errors[NB_UNPACK_TREES_ERROR_TYPES] = {
  20        /* ERROR_WOULD_OVERWRITE */
  21        "Entry '%s' would be overwritten by merge. Cannot merge.",
  22
  23        /* ERROR_NOT_UPTODATE_FILE */
  24        "Entry '%s' not uptodate. Cannot merge.",
  25
  26        /* ERROR_NOT_UPTODATE_DIR */
  27        "Updating '%s' would lose untracked files in it",
  28
  29        /* ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN */
  30        "Untracked working tree file '%s' would be overwritten by merge.",
  31
  32        /* ERROR_WOULD_LOSE_UNTRACKED_REMOVED */
  33        "Untracked working tree file '%s' would be removed by merge.",
  34
  35        /* ERROR_BIND_OVERLAP */
  36        "Entry '%s' overlaps with '%s'.  Cannot bind.",
  37
  38        /* ERROR_SPARSE_NOT_UPTODATE_FILE */
  39        "Entry '%s' not uptodate. Cannot update sparse checkout.",
  40
  41        /* ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN */
  42        "Working tree file '%s' would be overwritten by sparse checkout update.",
  43
  44        /* ERROR_WOULD_LOSE_ORPHANED_REMOVED */
  45        "Working tree file '%s' would be removed by sparse checkout update.",
  46};
  47
  48#define ERRORMSG(o,type) \
  49        ( ((o) && (o)->msgs[(type)]) \
  50          ? ((o)->msgs[(type)])      \
  51          : (unpack_plumbing_errors[(type)]) )
  52
  53void setup_unpack_trees_porcelain(struct unpack_trees_options *opts,
  54                                  const char *cmd)
  55{
  56        int i;
  57        const char **msgs = opts->msgs;
  58        const char *msg;
  59        char *tmp;
  60        const char *cmd2 = strcmp(cmd, "checkout") ? cmd : "switch branches";
  61        if (advice_commit_before_merge)
  62                msg = "Your local changes to the following files would be overwritten by %s:\n%%s"
  63                        "Please, commit your changes or stash them before you can %s.";
  64        else
  65                msg = "Your local changes to the following files would be overwritten by %s:\n%%s";
  66        tmp = xmalloc(strlen(msg) + strlen(cmd) + strlen(cmd2) - 2);
  67        sprintf(tmp, msg, cmd, cmd2);
  68        msgs[ERROR_WOULD_OVERWRITE] = tmp;
  69        msgs[ERROR_NOT_UPTODATE_FILE] = tmp;
  70
  71        msgs[ERROR_NOT_UPTODATE_DIR] =
  72                "Updating the following directories would lose untracked files in it:\n%s";
  73
  74        if (advice_commit_before_merge)
  75                msg = "The following untracked working tree files would be %s by %s:\n%%s"
  76                        "Please move or remove them before you can %s.";
  77        else
  78                msg = "The following untracked working tree files would be %s by %s:\n%%s";
  79        tmp = xmalloc(strlen(msg) + strlen(cmd) + strlen("removed") + strlen(cmd2) - 4);
  80        sprintf(tmp, msg, "removed", cmd, cmd2);
  81        msgs[ERROR_WOULD_LOSE_UNTRACKED_REMOVED] = tmp;
  82        tmp = xmalloc(strlen(msg) + strlen(cmd) + strlen("overwritten") + strlen(cmd2) - 4);
  83        sprintf(tmp, msg, "overwritten", cmd, cmd2);
  84        msgs[ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN] = tmp;
  85
  86        /*
  87         * Special case: ERROR_BIND_OVERLAP refers to a pair of paths, we
  88         * cannot easily display it as a list.
  89         */
  90        msgs[ERROR_BIND_OVERLAP] = "Entry '%s' overlaps with '%s'.  Cannot bind.";
  91
  92        msgs[ERROR_SPARSE_NOT_UPTODATE_FILE] =
  93                "Cannot update sparse checkout: the following entries are not up-to-date:\n%s";
  94        msgs[ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN] =
  95                "The following Working tree files would be overwritten by sparse checkout update:\n%s";
  96        msgs[ERROR_WOULD_LOSE_ORPHANED_REMOVED] =
  97                "The following Working tree files would be removed by sparse checkout update:\n%s";
  98
  99        opts->show_all_errors = 1;
 100        /* rejected paths may not have a static buffer */
 101        for (i = 0; i < ARRAY_SIZE(opts->unpack_rejects); i++)
 102                opts->unpack_rejects[i].strdup_strings = 1;
 103}
 104
 105static void do_add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
 106                         unsigned int set, unsigned int clear)
 107{
 108        clear |= CE_HASHED | CE_UNHASHED;
 109
 110        if (set & CE_REMOVE)
 111                set |= CE_WT_REMOVE;
 112
 113        ce->next = NULL;
 114        ce->ce_flags = (ce->ce_flags & ~clear) | set;
 115        add_index_entry(&o->result, ce,
 116                        ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 117}
 118
 119static void add_entry(struct unpack_trees_options *o, struct cache_entry *ce,
 120        unsigned int set, unsigned int clear)
 121{
 122        unsigned int size = ce_size(ce);
 123        struct cache_entry *new = xmalloc(size);
 124
 125        memcpy(new, ce, size);
 126        do_add_entry(o, new, set, clear);
 127}
 128
 129/*
 130 * add error messages on path <path>
 131 * corresponding to the type <e> with the message <msg>
 132 * indicating if it should be display in porcelain or not
 133 */
 134static int add_rejected_path(struct unpack_trees_options *o,
 135                             enum unpack_trees_error_types e,
 136                             const char *path)
 137{
 138        if (!o->show_all_errors)
 139                return error(ERRORMSG(o, e), path);
 140
 141        /*
 142         * Otherwise, insert in a list for future display by
 143         * display_error_msgs()
 144         */
 145        string_list_append(&o->unpack_rejects[e], path);
 146        return -1;
 147}
 148
 149/*
 150 * display all the error messages stored in a nice way
 151 */
 152static void display_error_msgs(struct unpack_trees_options *o)
 153{
 154        int e, i;
 155        int something_displayed = 0;
 156        for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
 157                struct string_list *rejects = &o->unpack_rejects[e];
 158                if (rejects->nr > 0) {
 159                        struct strbuf path = STRBUF_INIT;
 160                        something_displayed = 1;
 161                        for (i = 0; i < rejects->nr; i++)
 162                                strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
 163                        error(ERRORMSG(o, e), path.buf);
 164                        strbuf_release(&path);
 165                }
 166                string_list_clear(rejects, 0);
 167        }
 168        if (something_displayed)
 169                fprintf(stderr, "Aborting\n");
 170}
 171
 172/*
 173 * Unlink the last component and schedule the leading directories for
 174 * removal, such that empty directories get removed.
 175 */
 176static void unlink_entry(struct cache_entry *ce)
 177{
 178        if (!check_leading_path(ce->name, ce_namelen(ce)))
 179                return;
 180        if (remove_or_warn(ce->ce_mode, ce->name))
 181                return;
 182        schedule_dir_for_removal(ce->name, ce_namelen(ce));
 183}
 184
 185static struct checkout state;
 186static int check_updates(struct unpack_trees_options *o)
 187{
 188        unsigned cnt = 0, total = 0;
 189        struct progress *progress = NULL;
 190        struct index_state *index = &o->result;
 191        int i;
 192        int errs = 0;
 193
 194        if (o->update && o->verbose_update) {
 195                for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
 196                        struct cache_entry *ce = index->cache[cnt];
 197                        if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
 198                                total++;
 199                }
 200
 201                progress = start_progress_delay("Checking out files",
 202                                                total, 50, 1);
 203                cnt = 0;
 204        }
 205
 206        if (o->update)
 207                git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
 208        for (i = 0; i < index->cache_nr; i++) {
 209                struct cache_entry *ce = index->cache[i];
 210
 211                if (ce->ce_flags & CE_WT_REMOVE) {
 212                        display_progress(progress, ++cnt);
 213                        if (o->update && !o->dry_run)
 214                                unlink_entry(ce);
 215                        continue;
 216                }
 217        }
 218        remove_marked_cache_entries(&o->result);
 219        remove_scheduled_dirs();
 220
 221        for (i = 0; i < index->cache_nr; i++) {
 222                struct cache_entry *ce = index->cache[i];
 223
 224                if (ce->ce_flags & CE_UPDATE) {
 225                        display_progress(progress, ++cnt);
 226                        ce->ce_flags &= ~CE_UPDATE;
 227                        if (o->update && !o->dry_run) {
 228                                errs |= checkout_entry(ce, &state, NULL);
 229                        }
 230                }
 231        }
 232        stop_progress(&progress);
 233        if (o->update)
 234                git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
 235        return errs != 0;
 236}
 237
 238static int verify_uptodate_sparse(struct cache_entry *ce, struct unpack_trees_options *o);
 239static int verify_absent_sparse(struct cache_entry *ce, enum unpack_trees_error_types, struct unpack_trees_options *o);
 240
 241static int apply_sparse_checkout(struct cache_entry *ce, struct unpack_trees_options *o)
 242{
 243        int was_skip_worktree = ce_skip_worktree(ce);
 244
 245        if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
 246                ce->ce_flags |= CE_SKIP_WORKTREE;
 247        else
 248                ce->ce_flags &= ~CE_SKIP_WORKTREE;
 249
 250        /*
 251         * if (!was_skip_worktree && !ce_skip_worktree()) {
 252         *      This is perfectly normal. Move on;
 253         * }
 254         */
 255
 256        /*
 257         * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
 258         * area as a result of ce_skip_worktree() shortcuts in
 259         * verify_absent() and verify_uptodate().
 260         * Make sure they don't modify worktree if they are already
 261         * outside checkout area
 262         */
 263        if (was_skip_worktree && ce_skip_worktree(ce)) {
 264                ce->ce_flags &= ~CE_UPDATE;
 265
 266                /*
 267                 * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
 268                 * on to get that file removed from both index and worktree.
 269                 * If that file is already outside worktree area, don't
 270                 * bother remove it.
 271                 */
 272                if (ce->ce_flags & CE_REMOVE)
 273                        ce->ce_flags &= ~CE_WT_REMOVE;
 274        }
 275
 276        if (!was_skip_worktree && ce_skip_worktree(ce)) {
 277                /*
 278                 * If CE_UPDATE is set, verify_uptodate() must be called already
 279                 * also stat info may have lost after merged_entry() so calling
 280                 * verify_uptodate() again may fail
 281                 */
 282                if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
 283                        return -1;
 284                ce->ce_flags |= CE_WT_REMOVE;
 285        }
 286        if (was_skip_worktree && !ce_skip_worktree(ce)) {
 287                if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
 288                        return -1;
 289                ce->ce_flags |= CE_UPDATE;
 290        }
 291        return 0;
 292}
 293
 294static inline int call_unpack_fn(struct cache_entry **src, struct unpack_trees_options *o)
 295{
 296        int ret = o->fn(src, o);
 297        if (ret > 0)
 298                ret = 0;
 299        return ret;
 300}
 301
 302static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
 303{
 304        ce->ce_flags |= CE_UNPACKED;
 305
 306        if (o->cache_bottom < o->src_index->cache_nr &&
 307            o->src_index->cache[o->cache_bottom] == ce) {
 308                int bottom = o->cache_bottom;
 309                while (bottom < o->src_index->cache_nr &&
 310                       o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
 311                        bottom++;
 312                o->cache_bottom = bottom;
 313        }
 314}
 315
 316static void mark_all_ce_unused(struct index_state *index)
 317{
 318        int i;
 319        for (i = 0; i < index->cache_nr; i++)
 320                index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
 321}
 322
 323static int locate_in_src_index(struct cache_entry *ce,
 324                               struct unpack_trees_options *o)
 325{
 326        struct index_state *index = o->src_index;
 327        int len = ce_namelen(ce);
 328        int pos = index_name_pos(index, ce->name, len);
 329        if (pos < 0)
 330                pos = -1 - pos;
 331        return pos;
 332}
 333
 334/*
 335 * We call unpack_index_entry() with an unmerged cache entry
 336 * only in diff-index, and it wants a single callback.  Skip
 337 * the other unmerged entry with the same name.
 338 */
 339static void mark_ce_used_same_name(struct cache_entry *ce,
 340                                   struct unpack_trees_options *o)
 341{
 342        struct index_state *index = o->src_index;
 343        int len = ce_namelen(ce);
 344        int pos;
 345
 346        for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
 347                struct cache_entry *next = index->cache[pos];
 348                if (len != ce_namelen(next) ||
 349                    memcmp(ce->name, next->name, len))
 350                        break;
 351                mark_ce_used(next, o);
 352        }
 353}
 354
 355static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
 356{
 357        const struct index_state *index = o->src_index;
 358        int pos = o->cache_bottom;
 359
 360        while (pos < index->cache_nr) {
 361                struct cache_entry *ce = index->cache[pos];
 362                if (!(ce->ce_flags & CE_UNPACKED))
 363                        return ce;
 364                pos++;
 365        }
 366        return NULL;
 367}
 368
 369static void add_same_unmerged(struct cache_entry *ce,
 370                              struct unpack_trees_options *o)
 371{
 372        struct index_state *index = o->src_index;
 373        int len = ce_namelen(ce);
 374        int pos = index_name_pos(index, ce->name, len);
 375
 376        if (0 <= pos)
 377                die("programming error in a caller of mark_ce_used_same_name");
 378        for (pos = -pos - 1; pos < index->cache_nr; pos++) {
 379                struct cache_entry *next = index->cache[pos];
 380                if (len != ce_namelen(next) ||
 381                    memcmp(ce->name, next->name, len))
 382                        break;
 383                add_entry(o, next, 0, 0);
 384                mark_ce_used(next, o);
 385        }
 386}
 387
 388static int unpack_index_entry(struct cache_entry *ce,
 389                              struct unpack_trees_options *o)
 390{
 391        struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 392        int ret;
 393
 394        src[0] = ce;
 395
 396        mark_ce_used(ce, o);
 397        if (ce_stage(ce)) {
 398                if (o->skip_unmerged) {
 399                        add_entry(o, ce, 0, 0);
 400                        return 0;
 401                }
 402        }
 403        ret = call_unpack_fn(src, o);
 404        if (ce_stage(ce))
 405                mark_ce_used_same_name(ce, o);
 406        return ret;
 407}
 408
 409static int find_cache_pos(struct traverse_info *, const struct name_entry *);
 410
 411static void restore_cache_bottom(struct traverse_info *info, int bottom)
 412{
 413        struct unpack_trees_options *o = info->data;
 414
 415        if (o->diff_index_cached)
 416                return;
 417        o->cache_bottom = bottom;
 418}
 419
 420static int switch_cache_bottom(struct traverse_info *info)
 421{
 422        struct unpack_trees_options *o = info->data;
 423        int ret, pos;
 424
 425        if (o->diff_index_cached)
 426                return 0;
 427        ret = o->cache_bottom;
 428        pos = find_cache_pos(info->prev, &info->name);
 429
 430        if (pos < -1)
 431                o->cache_bottom = -2 - pos;
 432        else if (pos < 0)
 433                o->cache_bottom = o->src_index->cache_nr;
 434        return ret;
 435}
 436
 437static int traverse_trees_recursive(int n, unsigned long dirmask,
 438                                    unsigned long df_conflicts,
 439                                    struct name_entry *names,
 440                                    struct traverse_info *info)
 441{
 442        int i, ret, bottom;
 443        struct tree_desc t[MAX_UNPACK_TREES];
 444        void *buf[MAX_UNPACK_TREES];
 445        struct traverse_info newinfo;
 446        struct name_entry *p;
 447
 448        p = names;
 449        while (!p->mode)
 450                p++;
 451
 452        newinfo = *info;
 453        newinfo.prev = info;
 454        newinfo.pathspec = info->pathspec;
 455        newinfo.name = *p;
 456        newinfo.pathlen += tree_entry_len(p) + 1;
 457        newinfo.conflicts |= df_conflicts;
 458
 459        for (i = 0; i < n; i++, dirmask >>= 1) {
 460                const unsigned char *sha1 = NULL;
 461                if (dirmask & 1)
 462                        sha1 = names[i].sha1;
 463                buf[i] = fill_tree_descriptor(t+i, sha1);
 464        }
 465
 466        bottom = switch_cache_bottom(&newinfo);
 467        ret = traverse_trees(n, t, &newinfo);
 468        restore_cache_bottom(&newinfo, bottom);
 469
 470        for (i = 0; i < n; i++)
 471                free(buf[i]);
 472
 473        return ret;
 474}
 475
 476/*
 477 * Compare the traverse-path to the cache entry without actually
 478 * having to generate the textual representation of the traverse
 479 * path.
 480 *
 481 * NOTE! This *only* compares up to the size of the traverse path
 482 * itself - the caller needs to do the final check for the cache
 483 * entry having more data at the end!
 484 */
 485static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 486{
 487        int len, pathlen, ce_len;
 488        const char *ce_name;
 489
 490        if (info->prev) {
 491                int cmp = do_compare_entry(ce, info->prev, &info->name);
 492                if (cmp)
 493                        return cmp;
 494        }
 495        pathlen = info->pathlen;
 496        ce_len = ce_namelen(ce);
 497
 498        /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 499        if (ce_len < pathlen)
 500                return -1;
 501
 502        ce_len -= pathlen;
 503        ce_name = ce->name + pathlen;
 504
 505        len = tree_entry_len(n);
 506        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 507}
 508
 509static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 510{
 511        int cmp = do_compare_entry(ce, info, n);
 512        if (cmp)
 513                return cmp;
 514
 515        /*
 516         * Even if the beginning compared identically, the ce should
 517         * compare as bigger than a directory leading up to it!
 518         */
 519        return ce_namelen(ce) > traverse_path_len(info, n);
 520}
 521
 522static int ce_in_traverse_path(const struct cache_entry *ce,
 523                               const struct traverse_info *info)
 524{
 525        if (!info->prev)
 526                return 1;
 527        if (do_compare_entry(ce, info->prev, &info->name))
 528                return 0;
 529        /*
 530         * If ce (blob) is the same name as the path (which is a tree
 531         * we will be descending into), it won't be inside it.
 532         */
 533        return (info->pathlen < ce_namelen(ce));
 534}
 535
 536static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
 537{
 538        int len = traverse_path_len(info, n);
 539        struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
 540
 541        ce->ce_mode = create_ce_mode(n->mode);
 542        ce->ce_flags = create_ce_flags(stage);
 543        ce->ce_namelen = len;
 544        hashcpy(ce->sha1, n->sha1);
 545        make_traverse_path(ce->name, info, n);
 546
 547        return ce;
 548}
 549
 550static int unpack_nondirectories(int n, unsigned long mask,
 551                                 unsigned long dirmask,
 552                                 struct cache_entry **src,
 553                                 const struct name_entry *names,
 554                                 const struct traverse_info *info)
 555{
 556        int i;
 557        struct unpack_trees_options *o = info->data;
 558        unsigned long conflicts;
 559
 560        /* Do we have *only* directories? Nothing to do */
 561        if (mask == dirmask && !src[0])
 562                return 0;
 563
 564        conflicts = info->conflicts;
 565        if (o->merge)
 566                conflicts >>= 1;
 567        conflicts |= dirmask;
 568
 569        /*
 570         * Ok, we've filled in up to any potential index entry in src[0],
 571         * now do the rest.
 572         */
 573        for (i = 0; i < n; i++) {
 574                int stage;
 575                unsigned int bit = 1ul << i;
 576                if (conflicts & bit) {
 577                        src[i + o->merge] = o->df_conflict_entry;
 578                        continue;
 579                }
 580                if (!(mask & bit))
 581                        continue;
 582                if (!o->merge)
 583                        stage = 0;
 584                else if (i + 1 < o->head_idx)
 585                        stage = 1;
 586                else if (i + 1 > o->head_idx)
 587                        stage = 3;
 588                else
 589                        stage = 2;
 590                src[i + o->merge] = create_ce_entry(info, names + i, stage);
 591        }
 592
 593        if (o->merge)
 594                return call_unpack_fn(src, o);
 595
 596        for (i = 0; i < n; i++)
 597                if (src[i] && src[i] != o->df_conflict_entry)
 598                        do_add_entry(o, src[i], 0, 0);
 599        return 0;
 600}
 601
 602static int unpack_failed(struct unpack_trees_options *o, const char *message)
 603{
 604        discard_index(&o->result);
 605        if (!o->gently && !o->exiting_early) {
 606                if (message)
 607                        return error("%s", message);
 608                return -1;
 609        }
 610        return -1;
 611}
 612
 613/* NEEDSWORK: give this a better name and share with tree-walk.c */
 614static int name_compare(const char *a, int a_len,
 615                        const char *b, int b_len)
 616{
 617        int len = (a_len < b_len) ? a_len : b_len;
 618        int cmp = memcmp(a, b, len);
 619        if (cmp)
 620                return cmp;
 621        return (a_len - b_len);
 622}
 623
 624/*
 625 * The tree traversal is looking at name p.  If we have a matching entry,
 626 * return it.  If name p is a directory in the index, do not return
 627 * anything, as we will want to match it when the traversal descends into
 628 * the directory.
 629 */
 630static int find_cache_pos(struct traverse_info *info,
 631                          const struct name_entry *p)
 632{
 633        int pos;
 634        struct unpack_trees_options *o = info->data;
 635        struct index_state *index = o->src_index;
 636        int pfxlen = info->pathlen;
 637        int p_len = tree_entry_len(p);
 638
 639        for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
 640                struct cache_entry *ce = index->cache[pos];
 641                const char *ce_name, *ce_slash;
 642                int cmp, ce_len;
 643
 644                if (ce->ce_flags & CE_UNPACKED) {
 645                        /*
 646                         * cache_bottom entry is already unpacked, so
 647                         * we can never match it; don't check it
 648                         * again.
 649                         */
 650                        if (pos == o->cache_bottom)
 651                                ++o->cache_bottom;
 652                        continue;
 653                }
 654                if (!ce_in_traverse_path(ce, info))
 655                        continue;
 656                ce_name = ce->name + pfxlen;
 657                ce_slash = strchr(ce_name, '/');
 658                if (ce_slash)
 659                        ce_len = ce_slash - ce_name;
 660                else
 661                        ce_len = ce_namelen(ce) - pfxlen;
 662                cmp = name_compare(p->path, p_len, ce_name, ce_len);
 663                /*
 664                 * Exact match; if we have a directory we need to
 665                 * delay returning it.
 666                 */
 667                if (!cmp)
 668                        return ce_slash ? -2 - pos : pos;
 669                if (0 < cmp)
 670                        continue; /* keep looking */
 671                /*
 672                 * ce_name sorts after p->path; could it be that we
 673                 * have files under p->path directory in the index?
 674                 * E.g.  ce_name == "t-i", and p->path == "t"; we may
 675                 * have "t/a" in the index.
 676                 */
 677                if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
 678                    ce_name[p_len] < '/')
 679                        continue; /* keep looking */
 680                break;
 681        }
 682        return -1;
 683}
 684
 685static struct cache_entry *find_cache_entry(struct traverse_info *info,
 686                                            const struct name_entry *p)
 687{
 688        int pos = find_cache_pos(info, p);
 689        struct unpack_trees_options *o = info->data;
 690
 691        if (0 <= pos)
 692                return o->src_index->cache[pos];
 693        else
 694                return NULL;
 695}
 696
 697static void debug_path(struct traverse_info *info)
 698{
 699        if (info->prev) {
 700                debug_path(info->prev);
 701                if (*info->prev->name.path)
 702                        putchar('/');
 703        }
 704        printf("%s", info->name.path);
 705}
 706
 707static void debug_name_entry(int i, struct name_entry *n)
 708{
 709        printf("ent#%d %06o %s\n", i,
 710               n->path ? n->mode : 0,
 711               n->path ? n->path : "(missing)");
 712}
 713
 714static void debug_unpack_callback(int n,
 715                                  unsigned long mask,
 716                                  unsigned long dirmask,
 717                                  struct name_entry *names,
 718                                  struct traverse_info *info)
 719{
 720        int i;
 721        printf("* unpack mask %lu, dirmask %lu, cnt %d ",
 722               mask, dirmask, n);
 723        debug_path(info);
 724        putchar('\n');
 725        for (i = 0; i < n; i++)
 726                debug_name_entry(i, names + i);
 727}
 728
 729static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
 730{
 731        struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 732        struct unpack_trees_options *o = info->data;
 733        const struct name_entry *p = names;
 734
 735        /* Find first entry with a real name (we could use "mask" too) */
 736        while (!p->mode)
 737                p++;
 738
 739        if (o->debug_unpack)
 740                debug_unpack_callback(n, mask, dirmask, names, info);
 741
 742        /* Are we supposed to look at the index too? */
 743        if (o->merge) {
 744                while (1) {
 745                        int cmp;
 746                        struct cache_entry *ce;
 747
 748                        if (o->diff_index_cached)
 749                                ce = next_cache_entry(o);
 750                        else
 751                                ce = find_cache_entry(info, p);
 752
 753                        if (!ce)
 754                                break;
 755                        cmp = compare_entry(ce, info, p);
 756                        if (cmp < 0) {
 757                                if (unpack_index_entry(ce, o) < 0)
 758                                        return unpack_failed(o, NULL);
 759                                continue;
 760                        }
 761                        if (!cmp) {
 762                                if (ce_stage(ce)) {
 763                                        /*
 764                                         * If we skip unmerged index
 765                                         * entries, we'll skip this
 766                                         * entry *and* the tree
 767                                         * entries associated with it!
 768                                         */
 769                                        if (o->skip_unmerged) {
 770                                                add_same_unmerged(ce, o);
 771                                                return mask;
 772                                        }
 773                                }
 774                                src[0] = ce;
 775                        }
 776                        break;
 777                }
 778        }
 779
 780        if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
 781                return -1;
 782
 783        if (o->merge && src[0]) {
 784                if (ce_stage(src[0]))
 785                        mark_ce_used_same_name(src[0], o);
 786                else
 787                        mark_ce_used(src[0], o);
 788        }
 789
 790        /* Now handle any directories.. */
 791        if (dirmask) {
 792                unsigned long conflicts = mask & ~dirmask;
 793                if (o->merge) {
 794                        conflicts <<= 1;
 795                        if (src[0])
 796                                conflicts |= 1;
 797                }
 798
 799                /* special case: "diff-index --cached" looking at a tree */
 800                if (o->diff_index_cached &&
 801                    n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
 802                        int matches;
 803                        matches = cache_tree_matches_traversal(o->src_index->cache_tree,
 804                                                               names, info);
 805                        /*
 806                         * Everything under the name matches; skip the
 807                         * entire hierarchy.  diff_index_cached codepath
 808                         * special cases D/F conflicts in such a way that
 809                         * it does not do any look-ahead, so this is safe.
 810                         */
 811                        if (matches) {
 812                                o->cache_bottom += matches;
 813                                return mask;
 814                        }
 815                }
 816
 817                if (traverse_trees_recursive(n, dirmask, conflicts,
 818                                             names, info) < 0)
 819                        return -1;
 820                return mask;
 821        }
 822
 823        return mask;
 824}
 825
 826static int clear_ce_flags_1(struct cache_entry **cache, int nr,
 827                            char *prefix, int prefix_len,
 828                            int select_mask, int clear_mask,
 829                            struct exclude_list *el, int defval);
 830
 831/* Whole directory matching */
 832static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
 833                              char *prefix, int prefix_len,
 834                              char *basename,
 835                              int select_mask, int clear_mask,
 836                              struct exclude_list *el, int defval)
 837{
 838        struct cache_entry **cache_end;
 839        int dtype = DT_DIR;
 840        int ret = excluded_from_list(prefix, prefix_len, basename, &dtype, el);
 841
 842        prefix[prefix_len++] = '/';
 843
 844        /* If undecided, use matching result of parent dir in defval */
 845        if (ret < 0)
 846                ret = defval;
 847
 848        for (cache_end = cache; cache_end != cache + nr; cache_end++) {
 849                struct cache_entry *ce = *cache_end;
 850                if (strncmp(ce->name, prefix, prefix_len))
 851                        break;
 852        }
 853
 854        /*
 855         * TODO: check el, if there are no patterns that may conflict
 856         * with ret (iow, we know in advance the incl/excl
 857         * decision for the entire directory), clear flag here without
 858         * calling clear_ce_flags_1(). That function will call
 859         * the expensive excluded_from_list() on every entry.
 860         */
 861        return clear_ce_flags_1(cache, cache_end - cache,
 862                                prefix, prefix_len,
 863                                select_mask, clear_mask,
 864                                el, ret);
 865}
 866
 867/*
 868 * Traverse the index, find every entry that matches according to
 869 * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
 870 * number of traversed entries.
 871 *
 872 * If select_mask is non-zero, only entries whose ce_flags has on of
 873 * those bits enabled are traversed.
 874 *
 875 * cache        : pointer to an index entry
 876 * prefix_len   : an offset to its path
 877 *
 878 * The current path ("prefix") including the trailing '/' is
 879 *   cache[0]->name[0..(prefix_len-1)]
 880 * Top level path has prefix_len zero.
 881 */
 882static int clear_ce_flags_1(struct cache_entry **cache, int nr,
 883                            char *prefix, int prefix_len,
 884                            int select_mask, int clear_mask,
 885                            struct exclude_list *el, int defval)
 886{
 887        struct cache_entry **cache_end = cache + nr;
 888
 889        /*
 890         * Process all entries that have the given prefix and meet
 891         * select_mask condition
 892         */
 893        while(cache != cache_end) {
 894                struct cache_entry *ce = *cache;
 895                const char *name, *slash;
 896                int len, dtype, ret;
 897
 898                if (select_mask && !(ce->ce_flags & select_mask)) {
 899                        cache++;
 900                        continue;
 901                }
 902
 903                if (prefix_len && strncmp(ce->name, prefix, prefix_len))
 904                        break;
 905
 906                name = ce->name + prefix_len;
 907                slash = strchr(name, '/');
 908
 909                /* If it's a directory, try whole directory match first */
 910                if (slash) {
 911                        int processed;
 912
 913                        len = slash - name;
 914                        memcpy(prefix + prefix_len, name, len);
 915
 916                        /*
 917                         * terminate the string (no trailing slash),
 918                         * clear_c_f_dir needs it
 919                         */
 920                        prefix[prefix_len + len] = '\0';
 921                        processed = clear_ce_flags_dir(cache, cache_end - cache,
 922                                                       prefix, prefix_len + len,
 923                                                       prefix + prefix_len,
 924                                                       select_mask, clear_mask,
 925                                                       el, defval);
 926
 927                        /* clear_c_f_dir eats a whole dir already? */
 928                        if (processed) {
 929                                cache += processed;
 930                                continue;
 931                        }
 932
 933                        prefix[prefix_len + len++] = '/';
 934                        cache += clear_ce_flags_1(cache, cache_end - cache,
 935                                                  prefix, prefix_len + len,
 936                                                  select_mask, clear_mask, el, defval);
 937                        continue;
 938                }
 939
 940                /* Non-directory */
 941                dtype = ce_to_dtype(ce);
 942                ret = excluded_from_list(ce->name, ce_namelen(ce), name, &dtype, el);
 943                if (ret < 0)
 944                        ret = defval;
 945                if (ret > 0)
 946                        ce->ce_flags &= ~clear_mask;
 947                cache++;
 948        }
 949        return nr - (cache_end - cache);
 950}
 951
 952static int clear_ce_flags(struct cache_entry **cache, int nr,
 953                            int select_mask, int clear_mask,
 954                            struct exclude_list *el)
 955{
 956        char prefix[PATH_MAX];
 957        return clear_ce_flags_1(cache, nr,
 958                                prefix, 0,
 959                                select_mask, clear_mask,
 960                                el, 0);
 961}
 962
 963/*
 964 * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
 965 */
 966static void mark_new_skip_worktree(struct exclude_list *el,
 967                                   struct index_state *the_index,
 968                                   int select_flag, int skip_wt_flag)
 969{
 970        int i;
 971
 972        /*
 973         * 1. Pretend the narrowest worktree: only unmerged entries
 974         * are checked out
 975         */
 976        for (i = 0; i < the_index->cache_nr; i++) {
 977                struct cache_entry *ce = the_index->cache[i];
 978
 979                if (select_flag && !(ce->ce_flags & select_flag))
 980                        continue;
 981
 982                if (!ce_stage(ce))
 983                        ce->ce_flags |= skip_wt_flag;
 984                else
 985                        ce->ce_flags &= ~skip_wt_flag;
 986        }
 987
 988        /*
 989         * 2. Widen worktree according to sparse-checkout file.
 990         * Matched entries will have skip_wt_flag cleared (i.e. "in")
 991         */
 992        clear_ce_flags(the_index->cache, the_index->cache_nr,
 993                       select_flag, skip_wt_flag, el);
 994}
 995
 996static int verify_absent(struct cache_entry *, enum unpack_trees_error_types, struct unpack_trees_options *);
 997/*
 998 * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
 999 * resulting index, -2 on failure to reflect the changes to the work tree.
1000 *
1001 * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1002 */
1003int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1004{
1005        int i, ret;
1006        static struct cache_entry *dfc;
1007        struct exclude_list el;
1008
1009        if (len > MAX_UNPACK_TREES)
1010                die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1011        memset(&state, 0, sizeof(state));
1012        state.base_dir = "";
1013        state.force = 1;
1014        state.quiet = 1;
1015        state.refresh_cache = 1;
1016
1017        memset(&el, 0, sizeof(el));
1018        if (!core_apply_sparse_checkout || !o->update)
1019                o->skip_sparse_checkout = 1;
1020        if (!o->skip_sparse_checkout) {
1021                if (add_excludes_from_file_to_list(git_path("info/sparse-checkout"), "", 0, NULL, &el, 0) < 0)
1022                        o->skip_sparse_checkout = 1;
1023                else
1024                        o->el = &el;
1025        }
1026
1027        if (o->dir) {
1028                o->path_exclude_check = xmalloc(sizeof(struct path_exclude_check));
1029                path_exclude_check_init(o->path_exclude_check, o->dir);
1030        }
1031        memset(&o->result, 0, sizeof(o->result));
1032        o->result.initialized = 1;
1033        o->result.timestamp.sec = o->src_index->timestamp.sec;
1034        o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1035        o->result.version = o->src_index->version;
1036        o->merge_size = len;
1037        mark_all_ce_unused(o->src_index);
1038
1039        /*
1040         * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1041         */
1042        if (!o->skip_sparse_checkout)
1043                mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1044
1045        if (!dfc)
1046                dfc = xcalloc(1, cache_entry_size(0));
1047        o->df_conflict_entry = dfc;
1048
1049        if (len) {
1050                const char *prefix = o->prefix ? o->prefix : "";
1051                struct traverse_info info;
1052
1053                setup_traverse_info(&info, prefix);
1054                info.fn = unpack_callback;
1055                info.data = o;
1056                info.show_all_errors = o->show_all_errors;
1057                info.pathspec = o->pathspec;
1058
1059                if (o->prefix) {
1060                        /*
1061                         * Unpack existing index entries that sort before the
1062                         * prefix the tree is spliced into.  Note that o->merge
1063                         * is always true in this case.
1064                         */
1065                        while (1) {
1066                                struct cache_entry *ce = next_cache_entry(o);
1067                                if (!ce)
1068                                        break;
1069                                if (ce_in_traverse_path(ce, &info))
1070                                        break;
1071                                if (unpack_index_entry(ce, o) < 0)
1072                                        goto return_failed;
1073                        }
1074                }
1075
1076                if (traverse_trees(len, t, &info) < 0)
1077                        goto return_failed;
1078        }
1079
1080        /* Any left-over entries in the index? */
1081        if (o->merge) {
1082                while (1) {
1083                        struct cache_entry *ce = next_cache_entry(o);
1084                        if (!ce)
1085                                break;
1086                        if (unpack_index_entry(ce, o) < 0)
1087                                goto return_failed;
1088                }
1089        }
1090        mark_all_ce_unused(o->src_index);
1091
1092        if (o->trivial_merges_only && o->nontrivial_merge) {
1093                ret = unpack_failed(o, "Merge requires file-level merging");
1094                goto done;
1095        }
1096
1097        if (!o->skip_sparse_checkout) {
1098                int empty_worktree = 1;
1099
1100                /*
1101                 * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1102                 * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1103                 * so apply_sparse_checkout() won't attempt to remove it from worktree
1104                 */
1105                mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1106
1107                ret = 0;
1108                for (i = 0; i < o->result.cache_nr; i++) {
1109                        struct cache_entry *ce = o->result.cache[i];
1110
1111                        /*
1112                         * Entries marked with CE_ADDED in merged_entry() do not have
1113                         * verify_absent() check (the check is effectively disabled
1114                         * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1115                         *
1116                         * Do the real check now because we have had
1117                         * correct CE_NEW_SKIP_WORKTREE
1118                         */
1119                        if (ce->ce_flags & CE_ADDED &&
1120                            verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1121                                if (!o->show_all_errors)
1122                                        goto return_failed;
1123                                ret = -1;
1124                        }
1125
1126                        if (apply_sparse_checkout(ce, o)) {
1127                                if (!o->show_all_errors)
1128                                        goto return_failed;
1129                                ret = -1;
1130                        }
1131                        if (!ce_skip_worktree(ce))
1132                                empty_worktree = 0;
1133
1134                }
1135                if (ret < 0)
1136                        goto return_failed;
1137                /*
1138                 * Sparse checkout is meant to narrow down checkout area
1139                 * but it does not make sense to narrow down to empty working
1140                 * tree. This is usually a mistake in sparse checkout rules.
1141                 * Do not allow users to do that.
1142                 */
1143                if (o->result.cache_nr && empty_worktree) {
1144                        ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1145                        goto done;
1146                }
1147        }
1148
1149        o->src_index = NULL;
1150        ret = check_updates(o) ? (-2) : 0;
1151        if (o->dst_index)
1152                *o->dst_index = o->result;
1153
1154done:
1155        free_excludes(&el);
1156        if (o->path_exclude_check) {
1157                path_exclude_check_clear(o->path_exclude_check);
1158                free(o->path_exclude_check);
1159        }
1160        return ret;
1161
1162return_failed:
1163        if (o->show_all_errors)
1164                display_error_msgs(o);
1165        mark_all_ce_unused(o->src_index);
1166        ret = unpack_failed(o, NULL);
1167        if (o->exiting_early)
1168                ret = 0;
1169        goto done;
1170}
1171
1172/* Here come the merge functions */
1173
1174static int reject_merge(struct cache_entry *ce, struct unpack_trees_options *o)
1175{
1176        return add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1177}
1178
1179static int same(struct cache_entry *a, struct cache_entry *b)
1180{
1181        if (!!a != !!b)
1182                return 0;
1183        if (!a && !b)
1184                return 1;
1185        if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1186                return 0;
1187        return a->ce_mode == b->ce_mode &&
1188               !hashcmp(a->sha1, b->sha1);
1189}
1190
1191
1192/*
1193 * When a CE gets turned into an unmerged entry, we
1194 * want it to be up-to-date
1195 */
1196static int verify_uptodate_1(struct cache_entry *ce,
1197                                   struct unpack_trees_options *o,
1198                                   enum unpack_trees_error_types error_type)
1199{
1200        struct stat st;
1201
1202        if (o->index_only)
1203                return 0;
1204
1205        /*
1206         * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1207         * if this entry is truly up-to-date because this file may be
1208         * overwritten.
1209         */
1210        if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1211                ; /* keep checking */
1212        else if (o->reset || ce_uptodate(ce))
1213                return 0;
1214
1215        if (!lstat(ce->name, &st)) {
1216                int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1217                unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1218                if (!changed)
1219                        return 0;
1220                /*
1221                 * NEEDSWORK: the current default policy is to allow
1222                 * submodule to be out of sync wrt the superproject
1223                 * index.  This needs to be tightened later for
1224                 * submodules that are marked to be automatically
1225                 * checked out.
1226                 */
1227                if (S_ISGITLINK(ce->ce_mode))
1228                        return 0;
1229                errno = 0;
1230        }
1231        if (errno == ENOENT)
1232                return 0;
1233        return o->gently ? -1 :
1234                add_rejected_path(o, error_type, ce->name);
1235}
1236
1237static int verify_uptodate(struct cache_entry *ce,
1238                           struct unpack_trees_options *o)
1239{
1240        if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1241                return 0;
1242        return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1243}
1244
1245static int verify_uptodate_sparse(struct cache_entry *ce,
1246                                  struct unpack_trees_options *o)
1247{
1248        return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1249}
1250
1251static void invalidate_ce_path(struct cache_entry *ce, struct unpack_trees_options *o)
1252{
1253        if (ce)
1254                cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
1255}
1256
1257/*
1258 * Check that checking out ce->sha1 in subdir ce->name is not
1259 * going to overwrite any working files.
1260 *
1261 * Currently, git does not checkout subprojects during a superproject
1262 * checkout, so it is not going to overwrite anything.
1263 */
1264static int verify_clean_submodule(struct cache_entry *ce,
1265                                      enum unpack_trees_error_types error_type,
1266                                      struct unpack_trees_options *o)
1267{
1268        return 0;
1269}
1270
1271static int verify_clean_subdirectory(struct cache_entry *ce,
1272                                      enum unpack_trees_error_types error_type,
1273                                      struct unpack_trees_options *o)
1274{
1275        /*
1276         * we are about to extract "ce->name"; we would not want to lose
1277         * anything in the existing directory there.
1278         */
1279        int namelen;
1280        int i;
1281        struct dir_struct d;
1282        char *pathbuf;
1283        int cnt = 0;
1284        unsigned char sha1[20];
1285
1286        if (S_ISGITLINK(ce->ce_mode) &&
1287            resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
1288                /* If we are not going to update the submodule, then
1289                 * we don't care.
1290                 */
1291                if (!hashcmp(sha1, ce->sha1))
1292                        return 0;
1293                return verify_clean_submodule(ce, error_type, o);
1294        }
1295
1296        /*
1297         * First let's make sure we do not have a local modification
1298         * in that directory.
1299         */
1300        namelen = ce_namelen(ce);
1301        for (i = locate_in_src_index(ce, o);
1302             i < o->src_index->cache_nr;
1303             i++) {
1304                struct cache_entry *ce2 = o->src_index->cache[i];
1305                int len = ce_namelen(ce2);
1306                if (len < namelen ||
1307                    strncmp(ce->name, ce2->name, namelen) ||
1308                    ce2->name[namelen] != '/')
1309                        break;
1310                /*
1311                 * ce2->name is an entry in the subdirectory to be
1312                 * removed.
1313                 */
1314                if (!ce_stage(ce2)) {
1315                        if (verify_uptodate(ce2, o))
1316                                return -1;
1317                        add_entry(o, ce2, CE_REMOVE, 0);
1318                        mark_ce_used(ce2, o);
1319                }
1320                cnt++;
1321        }
1322
1323        /*
1324         * Then we need to make sure that we do not lose a locally
1325         * present file that is not ignored.
1326         */
1327        pathbuf = xmalloc(namelen + 2);
1328        memcpy(pathbuf, ce->name, namelen);
1329        strcpy(pathbuf+namelen, "/");
1330
1331        memset(&d, 0, sizeof(d));
1332        if (o->dir)
1333                d.exclude_per_dir = o->dir->exclude_per_dir;
1334        i = read_directory(&d, pathbuf, namelen+1, NULL);
1335        if (i)
1336                return o->gently ? -1 :
1337                        add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1338        free(pathbuf);
1339        return cnt;
1340}
1341
1342/*
1343 * This gets called when there was no index entry for the tree entry 'dst',
1344 * but we found a file in the working tree that 'lstat()' said was fine,
1345 * and we're on a case-insensitive filesystem.
1346 *
1347 * See if we can find a case-insensitive match in the index that also
1348 * matches the stat information, and assume it's that other file!
1349 */
1350static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1351{
1352        struct cache_entry *src;
1353
1354        src = index_name_exists(o->src_index, name, len, 1);
1355        return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1356}
1357
1358static int check_ok_to_remove(const char *name, int len, int dtype,
1359                              struct cache_entry *ce, struct stat *st,
1360                              enum unpack_trees_error_types error_type,
1361                              struct unpack_trees_options *o)
1362{
1363        struct cache_entry *result;
1364
1365        /*
1366         * It may be that the 'lstat()' succeeded even though
1367         * target 'ce' was absent, because there is an old
1368         * entry that is different only in case..
1369         *
1370         * Ignore that lstat() if it matches.
1371         */
1372        if (ignore_case && icase_exists(o, name, len, st))
1373                return 0;
1374
1375        if (o->dir &&
1376            path_excluded(o->path_exclude_check, name, -1, &dtype))
1377                /*
1378                 * ce->name is explicitly excluded, so it is Ok to
1379                 * overwrite it.
1380                 */
1381                return 0;
1382        if (S_ISDIR(st->st_mode)) {
1383                /*
1384                 * We are checking out path "foo" and
1385                 * found "foo/." in the working tree.
1386                 * This is tricky -- if we have modified
1387                 * files that are in "foo/" we would lose
1388                 * them.
1389                 */
1390                if (verify_clean_subdirectory(ce, error_type, o) < 0)
1391                        return -1;
1392                return 0;
1393        }
1394
1395        /*
1396         * The previous round may already have decided to
1397         * delete this path, which is in a subdirectory that
1398         * is being replaced with a blob.
1399         */
1400        result = index_name_exists(&o->result, name, len, 0);
1401        if (result) {
1402                if (result->ce_flags & CE_REMOVE)
1403                        return 0;
1404        }
1405
1406        return o->gently ? -1 :
1407                add_rejected_path(o, error_type, name);
1408}
1409
1410/*
1411 * We do not want to remove or overwrite a working tree file that
1412 * is not tracked, unless it is ignored.
1413 */
1414static int verify_absent_1(struct cache_entry *ce,
1415                                 enum unpack_trees_error_types error_type,
1416                                 struct unpack_trees_options *o)
1417{
1418        int len;
1419        struct stat st;
1420
1421        if (o->index_only || o->reset || !o->update)
1422                return 0;
1423
1424        len = check_leading_path(ce->name, ce_namelen(ce));
1425        if (!len)
1426                return 0;
1427        else if (len > 0) {
1428                char path[PATH_MAX + 1];
1429                memcpy(path, ce->name, len);
1430                path[len] = 0;
1431                if (lstat(path, &st))
1432                        return error("cannot stat '%s': %s", path,
1433                                        strerror(errno));
1434
1435                return check_ok_to_remove(path, len, DT_UNKNOWN, NULL, &st,
1436                                error_type, o);
1437        } else if (lstat(ce->name, &st)) {
1438                if (errno != ENOENT)
1439                        return error("cannot stat '%s': %s", ce->name,
1440                                     strerror(errno));
1441                return 0;
1442        } else {
1443                return check_ok_to_remove(ce->name, ce_namelen(ce),
1444                                          ce_to_dtype(ce), ce, &st,
1445                                          error_type, o);
1446        }
1447}
1448
1449static int verify_absent(struct cache_entry *ce,
1450                         enum unpack_trees_error_types error_type,
1451                         struct unpack_trees_options *o)
1452{
1453        if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1454                return 0;
1455        return verify_absent_1(ce, error_type, o);
1456}
1457
1458static int verify_absent_sparse(struct cache_entry *ce,
1459                         enum unpack_trees_error_types error_type,
1460                         struct unpack_trees_options *o)
1461{
1462        enum unpack_trees_error_types orphaned_error = error_type;
1463        if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1464                orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1465
1466        return verify_absent_1(ce, orphaned_error, o);
1467}
1468
1469static int merged_entry(struct cache_entry *merge, struct cache_entry *old,
1470                struct unpack_trees_options *o)
1471{
1472        int update = CE_UPDATE;
1473
1474        if (!old) {
1475                /*
1476                 * New index entries. In sparse checkout, the following
1477                 * verify_absent() will be delayed until after
1478                 * traverse_trees() finishes in unpack_trees(), then:
1479                 *
1480                 *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1481                 *  - verify_absent() be called again, this time with
1482                 *    correct CE_NEW_SKIP_WORKTREE
1483                 *
1484                 * verify_absent() call here does nothing in sparse
1485                 * checkout (i.e. o->skip_sparse_checkout == 0)
1486                 */
1487                update |= CE_ADDED;
1488                merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1489
1490                if (verify_absent(merge, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
1491                        return -1;
1492                invalidate_ce_path(merge, o);
1493        } else if (!(old->ce_flags & CE_CONFLICTED)) {
1494                /*
1495                 * See if we can re-use the old CE directly?
1496                 * That way we get the uptodate stat info.
1497                 *
1498                 * This also removes the UPDATE flag on a match; otherwise
1499                 * we will end up overwriting local changes in the work tree.
1500                 */
1501                if (same(old, merge)) {
1502                        copy_cache_entry(merge, old);
1503                        update = 0;
1504                } else {
1505                        if (verify_uptodate(old, o))
1506                                return -1;
1507                        /* Migrate old flags over */
1508                        update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1509                        invalidate_ce_path(old, o);
1510                }
1511        } else {
1512                /*
1513                 * Previously unmerged entry left as an existence
1514                 * marker by read_index_unmerged();
1515                 */
1516                invalidate_ce_path(old, o);
1517        }
1518
1519        add_entry(o, merge, update, CE_STAGEMASK);
1520        return 1;
1521}
1522
1523static int deleted_entry(struct cache_entry *ce, struct cache_entry *old,
1524                struct unpack_trees_options *o)
1525{
1526        /* Did it exist in the index? */
1527        if (!old) {
1528                if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1529                        return -1;
1530                return 0;
1531        }
1532        if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1533                return -1;
1534        add_entry(o, ce, CE_REMOVE, 0);
1535        invalidate_ce_path(ce, o);
1536        return 1;
1537}
1538
1539static int keep_entry(struct cache_entry *ce, struct unpack_trees_options *o)
1540{
1541        add_entry(o, ce, 0, 0);
1542        return 1;
1543}
1544
1545#if DBRT_DEBUG
1546static void show_stage_entry(FILE *o,
1547                             const char *label, const struct cache_entry *ce)
1548{
1549        if (!ce)
1550                fprintf(o, "%s (missing)\n", label);
1551        else
1552                fprintf(o, "%s%06o %s %d\t%s\n",
1553                        label,
1554                        ce->ce_mode,
1555                        sha1_to_hex(ce->sha1),
1556                        ce_stage(ce),
1557                        ce->name);
1558}
1559#endif
1560
1561int threeway_merge(struct cache_entry **stages, struct unpack_trees_options *o)
1562{
1563        struct cache_entry *index;
1564        struct cache_entry *head;
1565        struct cache_entry *remote = stages[o->head_idx + 1];
1566        int count;
1567        int head_match = 0;
1568        int remote_match = 0;
1569
1570        int df_conflict_head = 0;
1571        int df_conflict_remote = 0;
1572
1573        int any_anc_missing = 0;
1574        int no_anc_exists = 1;
1575        int i;
1576
1577        for (i = 1; i < o->head_idx; i++) {
1578                if (!stages[i] || stages[i] == o->df_conflict_entry)
1579                        any_anc_missing = 1;
1580                else
1581                        no_anc_exists = 0;
1582        }
1583
1584        index = stages[0];
1585        head = stages[o->head_idx];
1586
1587        if (head == o->df_conflict_entry) {
1588                df_conflict_head = 1;
1589                head = NULL;
1590        }
1591
1592        if (remote == o->df_conflict_entry) {
1593                df_conflict_remote = 1;
1594                remote = NULL;
1595        }
1596
1597        /*
1598         * First, if there's a #16 situation, note that to prevent #13
1599         * and #14.
1600         */
1601        if (!same(remote, head)) {
1602                for (i = 1; i < o->head_idx; i++) {
1603                        if (same(stages[i], head)) {
1604                                head_match = i;
1605                        }
1606                        if (same(stages[i], remote)) {
1607                                remote_match = i;
1608                        }
1609                }
1610        }
1611
1612        /*
1613         * We start with cases where the index is allowed to match
1614         * something other than the head: #14(ALT) and #2ALT, where it
1615         * is permitted to match the result instead.
1616         */
1617        /* #14, #14ALT, #2ALT */
1618        if (remote && !df_conflict_head && head_match && !remote_match) {
1619                if (index && !same(index, remote) && !same(index, head))
1620                        return o->gently ? -1 : reject_merge(index, o);
1621                return merged_entry(remote, index, o);
1622        }
1623        /*
1624         * If we have an entry in the index cache, then we want to
1625         * make sure that it matches head.
1626         */
1627        if (index && !same(index, head))
1628                return o->gently ? -1 : reject_merge(index, o);
1629
1630        if (head) {
1631                /* #5ALT, #15 */
1632                if (same(head, remote))
1633                        return merged_entry(head, index, o);
1634                /* #13, #3ALT */
1635                if (!df_conflict_remote && remote_match && !head_match)
1636                        return merged_entry(head, index, o);
1637        }
1638
1639        /* #1 */
1640        if (!head && !remote && any_anc_missing)
1641                return 0;
1642
1643        /*
1644         * Under the "aggressive" rule, we resolve mostly trivial
1645         * cases that we historically had git-merge-one-file resolve.
1646         */
1647        if (o->aggressive) {
1648                int head_deleted = !head;
1649                int remote_deleted = !remote;
1650                struct cache_entry *ce = NULL;
1651
1652                if (index)
1653                        ce = index;
1654                else if (head)
1655                        ce = head;
1656                else if (remote)
1657                        ce = remote;
1658                else {
1659                        for (i = 1; i < o->head_idx; i++) {
1660                                if (stages[i] && stages[i] != o->df_conflict_entry) {
1661                                        ce = stages[i];
1662                                        break;
1663                                }
1664                        }
1665                }
1666
1667                /*
1668                 * Deleted in both.
1669                 * Deleted in one and unchanged in the other.
1670                 */
1671                if ((head_deleted && remote_deleted) ||
1672                    (head_deleted && remote && remote_match) ||
1673                    (remote_deleted && head && head_match)) {
1674                        if (index)
1675                                return deleted_entry(index, index, o);
1676                        if (ce && !head_deleted) {
1677                                if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1678                                        return -1;
1679                        }
1680                        return 0;
1681                }
1682                /*
1683                 * Added in both, identically.
1684                 */
1685                if (no_anc_exists && head && remote && same(head, remote))
1686                        return merged_entry(head, index, o);
1687
1688        }
1689
1690        /* Below are "no merge" cases, which require that the index be
1691         * up-to-date to avoid the files getting overwritten with
1692         * conflict resolution files.
1693         */
1694        if (index) {
1695                if (verify_uptodate(index, o))
1696                        return -1;
1697        }
1698
1699        o->nontrivial_merge = 1;
1700
1701        /* #2, #3, #4, #6, #7, #9, #10, #11. */
1702        count = 0;
1703        if (!head_match || !remote_match) {
1704                for (i = 1; i < o->head_idx; i++) {
1705                        if (stages[i] && stages[i] != o->df_conflict_entry) {
1706                                keep_entry(stages[i], o);
1707                                count++;
1708                                break;
1709                        }
1710                }
1711        }
1712#if DBRT_DEBUG
1713        else {
1714                fprintf(stderr, "read-tree: warning #16 detected\n");
1715                show_stage_entry(stderr, "head   ", stages[head_match]);
1716                show_stage_entry(stderr, "remote ", stages[remote_match]);
1717        }
1718#endif
1719        if (head) { count += keep_entry(head, o); }
1720        if (remote) { count += keep_entry(remote, o); }
1721        return count;
1722}
1723
1724/*
1725 * Two-way merge.
1726 *
1727 * The rule is to "carry forward" what is in the index without losing
1728 * information across a "fast-forward", favoring a successful merge
1729 * over a merge failure when it makes sense.  For details of the
1730 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
1731 *
1732 */
1733int twoway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1734{
1735        struct cache_entry *current = src[0];
1736        struct cache_entry *oldtree = src[1];
1737        struct cache_entry *newtree = src[2];
1738
1739        if (o->merge_size != 2)
1740                return error("Cannot do a twoway merge of %d trees",
1741                             o->merge_size);
1742
1743        if (oldtree == o->df_conflict_entry)
1744                oldtree = NULL;
1745        if (newtree == o->df_conflict_entry)
1746                newtree = NULL;
1747
1748        if (current) {
1749                if ((!oldtree && !newtree) || /* 4 and 5 */
1750                    (!oldtree && newtree &&
1751                     same(current, newtree)) || /* 6 and 7 */
1752                    (oldtree && newtree &&
1753                     same(oldtree, newtree)) || /* 14 and 15 */
1754                    (oldtree && newtree &&
1755                     !same(oldtree, newtree) && /* 18 and 19 */
1756                     same(current, newtree))) {
1757                        return keep_entry(current, o);
1758                }
1759                else if (oldtree && !newtree && same(current, oldtree)) {
1760                        /* 10 or 11 */
1761                        return deleted_entry(oldtree, current, o);
1762                }
1763                else if (oldtree && newtree &&
1764                         same(current, oldtree) && !same(current, newtree)) {
1765                        /* 20 or 21 */
1766                        return merged_entry(newtree, current, o);
1767                }
1768                else {
1769                        /* all other failures */
1770                        if (oldtree)
1771                                return o->gently ? -1 : reject_merge(oldtree, o);
1772                        if (current)
1773                                return o->gently ? -1 : reject_merge(current, o);
1774                        if (newtree)
1775                                return o->gently ? -1 : reject_merge(newtree, o);
1776                        return -1;
1777                }
1778        }
1779        else if (newtree) {
1780                if (oldtree && !o->initial_checkout) {
1781                        /*
1782                         * deletion of the path was staged;
1783                         */
1784                        if (same(oldtree, newtree))
1785                                return 1;
1786                        return reject_merge(oldtree, o);
1787                }
1788                return merged_entry(newtree, current, o);
1789        }
1790        return deleted_entry(oldtree, current, o);
1791}
1792
1793/*
1794 * Bind merge.
1795 *
1796 * Keep the index entries at stage0, collapse stage1 but make sure
1797 * stage0 does not have anything there.
1798 */
1799int bind_merge(struct cache_entry **src,
1800                struct unpack_trees_options *o)
1801{
1802        struct cache_entry *old = src[0];
1803        struct cache_entry *a = src[1];
1804
1805        if (o->merge_size != 1)
1806                return error("Cannot do a bind merge of %d trees",
1807                             o->merge_size);
1808        if (a && old)
1809                return o->gently ? -1 :
1810                        error(ERRORMSG(o, ERROR_BIND_OVERLAP), a->name, old->name);
1811        if (!a)
1812                return keep_entry(old, o);
1813        else
1814                return merged_entry(a, NULL, o);
1815}
1816
1817/*
1818 * One-way merge.
1819 *
1820 * The rule is:
1821 * - take the stat information from stage0, take the data from stage1
1822 */
1823int oneway_merge(struct cache_entry **src, struct unpack_trees_options *o)
1824{
1825        struct cache_entry *old = src[0];
1826        struct cache_entry *a = src[1];
1827
1828        if (o->merge_size != 1)
1829                return error("Cannot do a oneway merge of %d trees",
1830                             o->merge_size);
1831
1832        if (!a || a == o->df_conflict_entry)
1833                return deleted_entry(old, old, o);
1834
1835        if (old && same(old, a)) {
1836                int update = 0;
1837                if (o->reset && !ce_uptodate(old) && !ce_skip_worktree(old)) {
1838                        struct stat st;
1839                        if (lstat(old->name, &st) ||
1840                            ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
1841                                update |= CE_UPDATE;
1842                }
1843                add_entry(o, old, update, 0);
1844                return 0;
1845        }
1846        return merged_entry(a, old, o);
1847}