unpack-trees.con commit apply: do not read from the filesystem under --index (3c37a2e)
   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 int 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        return add_index_entry(&o->result, ce,
 116                               ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
 117}
 118
 119static struct cache_entry *dup_entry(const struct cache_entry *ce)
 120{
 121        unsigned int size = ce_size(ce);
 122        struct cache_entry *new = xmalloc(size);
 123
 124        memcpy(new, ce, size);
 125        return new;
 126}
 127
 128static void add_entry(struct unpack_trees_options *o,
 129                      const struct cache_entry *ce,
 130                      unsigned int set, unsigned int clear)
 131{
 132        do_add_entry(o, dup_entry(ce), set, clear);
 133}
 134
 135/*
 136 * add error messages on path <path>
 137 * corresponding to the type <e> with the message <msg>
 138 * indicating if it should be display in porcelain or not
 139 */
 140static int add_rejected_path(struct unpack_trees_options *o,
 141                             enum unpack_trees_error_types e,
 142                             const char *path)
 143{
 144        if (!o->show_all_errors)
 145                return error(ERRORMSG(o, e), path);
 146
 147        /*
 148         * Otherwise, insert in a list for future display by
 149         * display_error_msgs()
 150         */
 151        string_list_append(&o->unpack_rejects[e], path);
 152        return -1;
 153}
 154
 155/*
 156 * display all the error messages stored in a nice way
 157 */
 158static void display_error_msgs(struct unpack_trees_options *o)
 159{
 160        int e, i;
 161        int something_displayed = 0;
 162        for (e = 0; e < NB_UNPACK_TREES_ERROR_TYPES; e++) {
 163                struct string_list *rejects = &o->unpack_rejects[e];
 164                if (rejects->nr > 0) {
 165                        struct strbuf path = STRBUF_INIT;
 166                        something_displayed = 1;
 167                        for (i = 0; i < rejects->nr; i++)
 168                                strbuf_addf(&path, "\t%s\n", rejects->items[i].string);
 169                        error(ERRORMSG(o, e), path.buf);
 170                        strbuf_release(&path);
 171                }
 172                string_list_clear(rejects, 0);
 173        }
 174        if (something_displayed)
 175                fprintf(stderr, "Aborting\n");
 176}
 177
 178/*
 179 * Unlink the last component and schedule the leading directories for
 180 * removal, such that empty directories get removed.
 181 */
 182static void unlink_entry(const struct cache_entry *ce)
 183{
 184        if (!check_leading_path(ce->name, ce_namelen(ce)))
 185                return;
 186        if (remove_or_warn(ce->ce_mode, ce->name))
 187                return;
 188        schedule_dir_for_removal(ce->name, ce_namelen(ce));
 189}
 190
 191static struct checkout state;
 192static int check_updates(struct unpack_trees_options *o)
 193{
 194        unsigned cnt = 0, total = 0;
 195        struct progress *progress = NULL;
 196        struct index_state *index = &o->result;
 197        int i;
 198        int errs = 0;
 199
 200        if (o->update && o->verbose_update) {
 201                for (total = cnt = 0; cnt < index->cache_nr; cnt++) {
 202                        const struct cache_entry *ce = index->cache[cnt];
 203                        if (ce->ce_flags & (CE_UPDATE | CE_WT_REMOVE))
 204                                total++;
 205                }
 206
 207                progress = start_progress_delay("Checking out files",
 208                                                total, 50, 1);
 209                cnt = 0;
 210        }
 211
 212        if (o->update)
 213                git_attr_set_direction(GIT_ATTR_CHECKOUT, &o->result);
 214        for (i = 0; i < index->cache_nr; i++) {
 215                const struct cache_entry *ce = index->cache[i];
 216
 217                if (ce->ce_flags & CE_WT_REMOVE) {
 218                        display_progress(progress, ++cnt);
 219                        if (o->update && !o->dry_run)
 220                                unlink_entry(ce);
 221                        continue;
 222                }
 223        }
 224        remove_marked_cache_entries(&o->result);
 225        remove_scheduled_dirs();
 226
 227        for (i = 0; i < index->cache_nr; i++) {
 228                struct cache_entry *ce = index->cache[i];
 229
 230                if (ce->ce_flags & CE_UPDATE) {
 231                        display_progress(progress, ++cnt);
 232                        ce->ce_flags &= ~CE_UPDATE;
 233                        if (o->update && !o->dry_run) {
 234                                errs |= checkout_entry(ce, &state, NULL);
 235                        }
 236                }
 237        }
 238        stop_progress(&progress);
 239        if (o->update)
 240                git_attr_set_direction(GIT_ATTR_CHECKIN, NULL);
 241        return errs != 0;
 242}
 243
 244static int verify_uptodate_sparse(const struct cache_entry *ce,
 245                                  struct unpack_trees_options *o);
 246static int verify_absent_sparse(const struct cache_entry *ce,
 247                                enum unpack_trees_error_types,
 248                                struct unpack_trees_options *o);
 249
 250static int apply_sparse_checkout(struct cache_entry *ce, struct unpack_trees_options *o)
 251{
 252        int was_skip_worktree = ce_skip_worktree(ce);
 253
 254        if (ce->ce_flags & CE_NEW_SKIP_WORKTREE)
 255                ce->ce_flags |= CE_SKIP_WORKTREE;
 256        else
 257                ce->ce_flags &= ~CE_SKIP_WORKTREE;
 258
 259        /*
 260         * if (!was_skip_worktree && !ce_skip_worktree()) {
 261         *      This is perfectly normal. Move on;
 262         * }
 263         */
 264
 265        /*
 266         * Merge strategies may set CE_UPDATE|CE_REMOVE outside checkout
 267         * area as a result of ce_skip_worktree() shortcuts in
 268         * verify_absent() and verify_uptodate().
 269         * Make sure they don't modify worktree if they are already
 270         * outside checkout area
 271         */
 272        if (was_skip_worktree && ce_skip_worktree(ce)) {
 273                ce->ce_flags &= ~CE_UPDATE;
 274
 275                /*
 276                 * By default, when CE_REMOVE is on, CE_WT_REMOVE is also
 277                 * on to get that file removed from both index and worktree.
 278                 * If that file is already outside worktree area, don't
 279                 * bother remove it.
 280                 */
 281                if (ce->ce_flags & CE_REMOVE)
 282                        ce->ce_flags &= ~CE_WT_REMOVE;
 283        }
 284
 285        if (!was_skip_worktree && ce_skip_worktree(ce)) {
 286                /*
 287                 * If CE_UPDATE is set, verify_uptodate() must be called already
 288                 * also stat info may have lost after merged_entry() so calling
 289                 * verify_uptodate() again may fail
 290                 */
 291                if (!(ce->ce_flags & CE_UPDATE) && verify_uptodate_sparse(ce, o))
 292                        return -1;
 293                ce->ce_flags |= CE_WT_REMOVE;
 294        }
 295        if (was_skip_worktree && !ce_skip_worktree(ce)) {
 296                if (verify_absent_sparse(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o))
 297                        return -1;
 298                ce->ce_flags |= CE_UPDATE;
 299        }
 300        return 0;
 301}
 302
 303static inline int call_unpack_fn(const struct cache_entry * const *src,
 304                                 struct unpack_trees_options *o)
 305{
 306        int ret = o->fn(src, o);
 307        if (ret > 0)
 308                ret = 0;
 309        return ret;
 310}
 311
 312static void mark_ce_used(struct cache_entry *ce, struct unpack_trees_options *o)
 313{
 314        ce->ce_flags |= CE_UNPACKED;
 315
 316        if (o->cache_bottom < o->src_index->cache_nr &&
 317            o->src_index->cache[o->cache_bottom] == ce) {
 318                int bottom = o->cache_bottom;
 319                while (bottom < o->src_index->cache_nr &&
 320                       o->src_index->cache[bottom]->ce_flags & CE_UNPACKED)
 321                        bottom++;
 322                o->cache_bottom = bottom;
 323        }
 324}
 325
 326static void mark_all_ce_unused(struct index_state *index)
 327{
 328        int i;
 329        for (i = 0; i < index->cache_nr; i++)
 330                index->cache[i]->ce_flags &= ~(CE_UNPACKED | CE_ADDED | CE_NEW_SKIP_WORKTREE);
 331}
 332
 333static int locate_in_src_index(const struct cache_entry *ce,
 334                               struct unpack_trees_options *o)
 335{
 336        struct index_state *index = o->src_index;
 337        int len = ce_namelen(ce);
 338        int pos = index_name_pos(index, ce->name, len);
 339        if (pos < 0)
 340                pos = -1 - pos;
 341        return pos;
 342}
 343
 344/*
 345 * We call unpack_index_entry() with an unmerged cache entry
 346 * only in diff-index, and it wants a single callback.  Skip
 347 * the other unmerged entry with the same name.
 348 */
 349static void mark_ce_used_same_name(struct cache_entry *ce,
 350                                   struct unpack_trees_options *o)
 351{
 352        struct index_state *index = o->src_index;
 353        int len = ce_namelen(ce);
 354        int pos;
 355
 356        for (pos = locate_in_src_index(ce, o); pos < index->cache_nr; pos++) {
 357                struct cache_entry *next = index->cache[pos];
 358                if (len != ce_namelen(next) ||
 359                    memcmp(ce->name, next->name, len))
 360                        break;
 361                mark_ce_used(next, o);
 362        }
 363}
 364
 365static struct cache_entry *next_cache_entry(struct unpack_trees_options *o)
 366{
 367        const struct index_state *index = o->src_index;
 368        int pos = o->cache_bottom;
 369
 370        while (pos < index->cache_nr) {
 371                struct cache_entry *ce = index->cache[pos];
 372                if (!(ce->ce_flags & CE_UNPACKED))
 373                        return ce;
 374                pos++;
 375        }
 376        return NULL;
 377}
 378
 379static void add_same_unmerged(const struct cache_entry *ce,
 380                              struct unpack_trees_options *o)
 381{
 382        struct index_state *index = o->src_index;
 383        int len = ce_namelen(ce);
 384        int pos = index_name_pos(index, ce->name, len);
 385
 386        if (0 <= pos)
 387                die("programming error in a caller of mark_ce_used_same_name");
 388        for (pos = -pos - 1; pos < index->cache_nr; pos++) {
 389                struct cache_entry *next = index->cache[pos];
 390                if (len != ce_namelen(next) ||
 391                    memcmp(ce->name, next->name, len))
 392                        break;
 393                add_entry(o, next, 0, 0);
 394                mark_ce_used(next, o);
 395        }
 396}
 397
 398static int unpack_index_entry(struct cache_entry *ce,
 399                              struct unpack_trees_options *o)
 400{
 401        const struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 402        int ret;
 403
 404        src[0] = ce;
 405
 406        mark_ce_used(ce, o);
 407        if (ce_stage(ce)) {
 408                if (o->skip_unmerged) {
 409                        add_entry(o, ce, 0, 0);
 410                        return 0;
 411                }
 412        }
 413        ret = call_unpack_fn(src, o);
 414        if (ce_stage(ce))
 415                mark_ce_used_same_name(ce, o);
 416        return ret;
 417}
 418
 419static int find_cache_pos(struct traverse_info *, const struct name_entry *);
 420
 421static void restore_cache_bottom(struct traverse_info *info, int bottom)
 422{
 423        struct unpack_trees_options *o = info->data;
 424
 425        if (o->diff_index_cached)
 426                return;
 427        o->cache_bottom = bottom;
 428}
 429
 430static int switch_cache_bottom(struct traverse_info *info)
 431{
 432        struct unpack_trees_options *o = info->data;
 433        int ret, pos;
 434
 435        if (o->diff_index_cached)
 436                return 0;
 437        ret = o->cache_bottom;
 438        pos = find_cache_pos(info->prev, &info->name);
 439
 440        if (pos < -1)
 441                o->cache_bottom = -2 - pos;
 442        else if (pos < 0)
 443                o->cache_bottom = o->src_index->cache_nr;
 444        return ret;
 445}
 446
 447static int traverse_trees_recursive(int n, unsigned long dirmask,
 448                                    unsigned long df_conflicts,
 449                                    struct name_entry *names,
 450                                    struct traverse_info *info)
 451{
 452        int i, ret, bottom;
 453        struct tree_desc t[MAX_UNPACK_TREES];
 454        void *buf[MAX_UNPACK_TREES];
 455        struct traverse_info newinfo;
 456        struct name_entry *p;
 457
 458        p = names;
 459        while (!p->mode)
 460                p++;
 461
 462        newinfo = *info;
 463        newinfo.prev = info;
 464        newinfo.pathspec = info->pathspec;
 465        newinfo.name = *p;
 466        newinfo.pathlen += tree_entry_len(p) + 1;
 467        newinfo.df_conflicts |= df_conflicts;
 468
 469        for (i = 0; i < n; i++, dirmask >>= 1) {
 470                const unsigned char *sha1 = NULL;
 471                if (dirmask & 1)
 472                        sha1 = names[i].sha1;
 473                buf[i] = fill_tree_descriptor(t+i, sha1);
 474        }
 475
 476        bottom = switch_cache_bottom(&newinfo);
 477        ret = traverse_trees(n, t, &newinfo);
 478        restore_cache_bottom(&newinfo, bottom);
 479
 480        for (i = 0; i < n; i++)
 481                free(buf[i]);
 482
 483        return ret;
 484}
 485
 486/*
 487 * Compare the traverse-path to the cache entry without actually
 488 * having to generate the textual representation of the traverse
 489 * path.
 490 *
 491 * NOTE! This *only* compares up to the size of the traverse path
 492 * itself - the caller needs to do the final check for the cache
 493 * entry having more data at the end!
 494 */
 495static int do_compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 496{
 497        int len, pathlen, ce_len;
 498        const char *ce_name;
 499
 500        if (info->prev) {
 501                int cmp = do_compare_entry(ce, info->prev, &info->name);
 502                if (cmp)
 503                        return cmp;
 504        }
 505        pathlen = info->pathlen;
 506        ce_len = ce_namelen(ce);
 507
 508        /* If ce_len < pathlen then we must have previously hit "name == directory" entry */
 509        if (ce_len < pathlen)
 510                return -1;
 511
 512        ce_len -= pathlen;
 513        ce_name = ce->name + pathlen;
 514
 515        len = tree_entry_len(n);
 516        return df_name_compare(ce_name, ce_len, S_IFREG, n->path, len, n->mode);
 517}
 518
 519static int compare_entry(const struct cache_entry *ce, const struct traverse_info *info, const struct name_entry *n)
 520{
 521        int cmp = do_compare_entry(ce, info, n);
 522        if (cmp)
 523                return cmp;
 524
 525        /*
 526         * Even if the beginning compared identically, the ce should
 527         * compare as bigger than a directory leading up to it!
 528         */
 529        return ce_namelen(ce) > traverse_path_len(info, n);
 530}
 531
 532static int ce_in_traverse_path(const struct cache_entry *ce,
 533                               const struct traverse_info *info)
 534{
 535        if (!info->prev)
 536                return 1;
 537        if (do_compare_entry(ce, info->prev, &info->name))
 538                return 0;
 539        /*
 540         * If ce (blob) is the same name as the path (which is a tree
 541         * we will be descending into), it won't be inside it.
 542         */
 543        return (info->pathlen < ce_namelen(ce));
 544}
 545
 546static struct cache_entry *create_ce_entry(const struct traverse_info *info, const struct name_entry *n, int stage)
 547{
 548        int len = traverse_path_len(info, n);
 549        struct cache_entry *ce = xcalloc(1, cache_entry_size(len));
 550
 551        ce->ce_mode = create_ce_mode(n->mode);
 552        ce->ce_flags = create_ce_flags(stage);
 553        ce->ce_namelen = len;
 554        hashcpy(ce->sha1, n->sha1);
 555        make_traverse_path(ce->name, info, n);
 556
 557        return ce;
 558}
 559
 560static int unpack_nondirectories(int n, unsigned long mask,
 561                                 unsigned long dirmask,
 562                                 struct cache_entry **src,
 563                                 const struct name_entry *names,
 564                                 const struct traverse_info *info)
 565{
 566        int i;
 567        struct unpack_trees_options *o = info->data;
 568        unsigned long conflicts = info->df_conflicts | dirmask;
 569
 570        /* Do we have *only* directories? Nothing to do */
 571        if (mask == dirmask && !src[0])
 572                return 0;
 573
 574        /*
 575         * Ok, we've filled in up to any potential index entry in src[0],
 576         * now do the rest.
 577         */
 578        for (i = 0; i < n; i++) {
 579                int stage;
 580                unsigned int bit = 1ul << i;
 581                if (conflicts & bit) {
 582                        src[i + o->merge] = o->df_conflict_entry;
 583                        continue;
 584                }
 585                if (!(mask & bit))
 586                        continue;
 587                if (!o->merge)
 588                        stage = 0;
 589                else if (i + 1 < o->head_idx)
 590                        stage = 1;
 591                else if (i + 1 > o->head_idx)
 592                        stage = 3;
 593                else
 594                        stage = 2;
 595                src[i + o->merge] = create_ce_entry(info, names + i, stage);
 596        }
 597
 598        if (o->merge) {
 599                int rc = call_unpack_fn((const struct cache_entry * const *)src,
 600                                        o);
 601                for (i = 0; i < n; i++) {
 602                        struct cache_entry *ce = src[i + o->merge];
 603                        if (ce != o->df_conflict_entry)
 604                                free(ce);
 605                }
 606                return rc;
 607        }
 608
 609        for (i = 0; i < n; i++)
 610                if (src[i] && src[i] != o->df_conflict_entry)
 611                        if (do_add_entry(o, src[i], 0, 0))
 612                                return -1;
 613
 614        return 0;
 615}
 616
 617static int unpack_failed(struct unpack_trees_options *o, const char *message)
 618{
 619        discard_index(&o->result);
 620        if (!o->gently && !o->exiting_early) {
 621                if (message)
 622                        return error("%s", message);
 623                return -1;
 624        }
 625        return -1;
 626}
 627
 628/* NEEDSWORK: give this a better name and share with tree-walk.c */
 629static int name_compare(const char *a, int a_len,
 630                        const char *b, int b_len)
 631{
 632        int len = (a_len < b_len) ? a_len : b_len;
 633        int cmp = memcmp(a, b, len);
 634        if (cmp)
 635                return cmp;
 636        return (a_len - b_len);
 637}
 638
 639/*
 640 * The tree traversal is looking at name p.  If we have a matching entry,
 641 * return it.  If name p is a directory in the index, do not return
 642 * anything, as we will want to match it when the traversal descends into
 643 * the directory.
 644 */
 645static int find_cache_pos(struct traverse_info *info,
 646                          const struct name_entry *p)
 647{
 648        int pos;
 649        struct unpack_trees_options *o = info->data;
 650        struct index_state *index = o->src_index;
 651        int pfxlen = info->pathlen;
 652        int p_len = tree_entry_len(p);
 653
 654        for (pos = o->cache_bottom; pos < index->cache_nr; pos++) {
 655                const struct cache_entry *ce = index->cache[pos];
 656                const char *ce_name, *ce_slash;
 657                int cmp, ce_len;
 658
 659                if (ce->ce_flags & CE_UNPACKED) {
 660                        /*
 661                         * cache_bottom entry is already unpacked, so
 662                         * we can never match it; don't check it
 663                         * again.
 664                         */
 665                        if (pos == o->cache_bottom)
 666                                ++o->cache_bottom;
 667                        continue;
 668                }
 669                if (!ce_in_traverse_path(ce, info))
 670                        continue;
 671                ce_name = ce->name + pfxlen;
 672                ce_slash = strchr(ce_name, '/');
 673                if (ce_slash)
 674                        ce_len = ce_slash - ce_name;
 675                else
 676                        ce_len = ce_namelen(ce) - pfxlen;
 677                cmp = name_compare(p->path, p_len, ce_name, ce_len);
 678                /*
 679                 * Exact match; if we have a directory we need to
 680                 * delay returning it.
 681                 */
 682                if (!cmp)
 683                        return ce_slash ? -2 - pos : pos;
 684                if (0 < cmp)
 685                        continue; /* keep looking */
 686                /*
 687                 * ce_name sorts after p->path; could it be that we
 688                 * have files under p->path directory in the index?
 689                 * E.g.  ce_name == "t-i", and p->path == "t"; we may
 690                 * have "t/a" in the index.
 691                 */
 692                if (p_len < ce_len && !memcmp(ce_name, p->path, p_len) &&
 693                    ce_name[p_len] < '/')
 694                        continue; /* keep looking */
 695                break;
 696        }
 697        return -1;
 698}
 699
 700static struct cache_entry *find_cache_entry(struct traverse_info *info,
 701                                            const struct name_entry *p)
 702{
 703        int pos = find_cache_pos(info, p);
 704        struct unpack_trees_options *o = info->data;
 705
 706        if (0 <= pos)
 707                return o->src_index->cache[pos];
 708        else
 709                return NULL;
 710}
 711
 712static void debug_path(struct traverse_info *info)
 713{
 714        if (info->prev) {
 715                debug_path(info->prev);
 716                if (*info->prev->name.path)
 717                        putchar('/');
 718        }
 719        printf("%s", info->name.path);
 720}
 721
 722static void debug_name_entry(int i, struct name_entry *n)
 723{
 724        printf("ent#%d %06o %s\n", i,
 725               n->path ? n->mode : 0,
 726               n->path ? n->path : "(missing)");
 727}
 728
 729static void debug_unpack_callback(int n,
 730                                  unsigned long mask,
 731                                  unsigned long dirmask,
 732                                  struct name_entry *names,
 733                                  struct traverse_info *info)
 734{
 735        int i;
 736        printf("* unpack mask %lu, dirmask %lu, cnt %d ",
 737               mask, dirmask, n);
 738        debug_path(info);
 739        putchar('\n');
 740        for (i = 0; i < n; i++)
 741                debug_name_entry(i, names + i);
 742}
 743
 744static int unpack_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *names, struct traverse_info *info)
 745{
 746        struct cache_entry *src[MAX_UNPACK_TREES + 1] = { NULL, };
 747        struct unpack_trees_options *o = info->data;
 748        const struct name_entry *p = names;
 749
 750        /* Find first entry with a real name (we could use "mask" too) */
 751        while (!p->mode)
 752                p++;
 753
 754        if (o->debug_unpack)
 755                debug_unpack_callback(n, mask, dirmask, names, info);
 756
 757        /* Are we supposed to look at the index too? */
 758        if (o->merge) {
 759                while (1) {
 760                        int cmp;
 761                        struct cache_entry *ce;
 762
 763                        if (o->diff_index_cached)
 764                                ce = next_cache_entry(o);
 765                        else
 766                                ce = find_cache_entry(info, p);
 767
 768                        if (!ce)
 769                                break;
 770                        cmp = compare_entry(ce, info, p);
 771                        if (cmp < 0) {
 772                                if (unpack_index_entry(ce, o) < 0)
 773                                        return unpack_failed(o, NULL);
 774                                continue;
 775                        }
 776                        if (!cmp) {
 777                                if (ce_stage(ce)) {
 778                                        /*
 779                                         * If we skip unmerged index
 780                                         * entries, we'll skip this
 781                                         * entry *and* the tree
 782                                         * entries associated with it!
 783                                         */
 784                                        if (o->skip_unmerged) {
 785                                                add_same_unmerged(ce, o);
 786                                                return mask;
 787                                        }
 788                                }
 789                                src[0] = ce;
 790                        }
 791                        break;
 792                }
 793        }
 794
 795        if (unpack_nondirectories(n, mask, dirmask, src, names, info) < 0)
 796                return -1;
 797
 798        if (o->merge && src[0]) {
 799                if (ce_stage(src[0]))
 800                        mark_ce_used_same_name(src[0], o);
 801                else
 802                        mark_ce_used(src[0], o);
 803        }
 804
 805        /* Now handle any directories.. */
 806        if (dirmask) {
 807                /* special case: "diff-index --cached" looking at a tree */
 808                if (o->diff_index_cached &&
 809                    n == 1 && dirmask == 1 && S_ISDIR(names->mode)) {
 810                        int matches;
 811                        matches = cache_tree_matches_traversal(o->src_index->cache_tree,
 812                                                               names, info);
 813                        /*
 814                         * Everything under the name matches; skip the
 815                         * entire hierarchy.  diff_index_cached codepath
 816                         * special cases D/F conflicts in such a way that
 817                         * it does not do any look-ahead, so this is safe.
 818                         */
 819                        if (matches) {
 820                                o->cache_bottom += matches;
 821                                return mask;
 822                        }
 823                }
 824
 825                if (traverse_trees_recursive(n, dirmask, mask & ~dirmask,
 826                                             names, info) < 0)
 827                        return -1;
 828                return mask;
 829        }
 830
 831        return mask;
 832}
 833
 834static int clear_ce_flags_1(struct cache_entry **cache, int nr,
 835                            char *prefix, int prefix_len,
 836                            int select_mask, int clear_mask,
 837                            struct exclude_list *el, int defval);
 838
 839/* Whole directory matching */
 840static int clear_ce_flags_dir(struct cache_entry **cache, int nr,
 841                              char *prefix, int prefix_len,
 842                              char *basename,
 843                              int select_mask, int clear_mask,
 844                              struct exclude_list *el, int defval)
 845{
 846        struct cache_entry **cache_end;
 847        int dtype = DT_DIR;
 848        int ret = is_excluded_from_list(prefix, prefix_len,
 849                                        basename, &dtype, el);
 850
 851        prefix[prefix_len++] = '/';
 852
 853        /* If undecided, use matching result of parent dir in defval */
 854        if (ret < 0)
 855                ret = defval;
 856
 857        for (cache_end = cache; cache_end != cache + nr; cache_end++) {
 858                struct cache_entry *ce = *cache_end;
 859                if (strncmp(ce->name, prefix, prefix_len))
 860                        break;
 861        }
 862
 863        /*
 864         * TODO: check el, if there are no patterns that may conflict
 865         * with ret (iow, we know in advance the incl/excl
 866         * decision for the entire directory), clear flag here without
 867         * calling clear_ce_flags_1(). That function will call
 868         * the expensive is_excluded_from_list() on every entry.
 869         */
 870        return clear_ce_flags_1(cache, cache_end - cache,
 871                                prefix, prefix_len,
 872                                select_mask, clear_mask,
 873                                el, ret);
 874}
 875
 876/*
 877 * Traverse the index, find every entry that matches according to
 878 * o->el. Do "ce_flags &= ~clear_mask" on those entries. Return the
 879 * number of traversed entries.
 880 *
 881 * If select_mask is non-zero, only entries whose ce_flags has on of
 882 * those bits enabled are traversed.
 883 *
 884 * cache        : pointer to an index entry
 885 * prefix_len   : an offset to its path
 886 *
 887 * The current path ("prefix") including the trailing '/' is
 888 *   cache[0]->name[0..(prefix_len-1)]
 889 * Top level path has prefix_len zero.
 890 */
 891static int clear_ce_flags_1(struct cache_entry **cache, int nr,
 892                            char *prefix, int prefix_len,
 893                            int select_mask, int clear_mask,
 894                            struct exclude_list *el, int defval)
 895{
 896        struct cache_entry **cache_end = cache + nr;
 897
 898        /*
 899         * Process all entries that have the given prefix and meet
 900         * select_mask condition
 901         */
 902        while(cache != cache_end) {
 903                struct cache_entry *ce = *cache;
 904                const char *name, *slash;
 905                int len, dtype, ret;
 906
 907                if (select_mask && !(ce->ce_flags & select_mask)) {
 908                        cache++;
 909                        continue;
 910                }
 911
 912                if (prefix_len && strncmp(ce->name, prefix, prefix_len))
 913                        break;
 914
 915                name = ce->name + prefix_len;
 916                slash = strchr(name, '/');
 917
 918                /* If it's a directory, try whole directory match first */
 919                if (slash) {
 920                        int processed;
 921
 922                        len = slash - name;
 923                        memcpy(prefix + prefix_len, name, len);
 924
 925                        /*
 926                         * terminate the string (no trailing slash),
 927                         * clear_c_f_dir needs it
 928                         */
 929                        prefix[prefix_len + len] = '\0';
 930                        processed = clear_ce_flags_dir(cache, cache_end - cache,
 931                                                       prefix, prefix_len + len,
 932                                                       prefix + prefix_len,
 933                                                       select_mask, clear_mask,
 934                                                       el, defval);
 935
 936                        /* clear_c_f_dir eats a whole dir already? */
 937                        if (processed) {
 938                                cache += processed;
 939                                continue;
 940                        }
 941
 942                        prefix[prefix_len + len++] = '/';
 943                        cache += clear_ce_flags_1(cache, cache_end - cache,
 944                                                  prefix, prefix_len + len,
 945                                                  select_mask, clear_mask, el, defval);
 946                        continue;
 947                }
 948
 949                /* Non-directory */
 950                dtype = ce_to_dtype(ce);
 951                ret = is_excluded_from_list(ce->name, ce_namelen(ce),
 952                                            name, &dtype, el);
 953                if (ret < 0)
 954                        ret = defval;
 955                if (ret > 0)
 956                        ce->ce_flags &= ~clear_mask;
 957                cache++;
 958        }
 959        return nr - (cache_end - cache);
 960}
 961
 962static int clear_ce_flags(struct cache_entry **cache, int nr,
 963                            int select_mask, int clear_mask,
 964                            struct exclude_list *el)
 965{
 966        char prefix[PATH_MAX];
 967        return clear_ce_flags_1(cache, nr,
 968                                prefix, 0,
 969                                select_mask, clear_mask,
 970                                el, 0);
 971}
 972
 973/*
 974 * Set/Clear CE_NEW_SKIP_WORKTREE according to $GIT_DIR/info/sparse-checkout
 975 */
 976static void mark_new_skip_worktree(struct exclude_list *el,
 977                                   struct index_state *the_index,
 978                                   int select_flag, int skip_wt_flag)
 979{
 980        int i;
 981
 982        /*
 983         * 1. Pretend the narrowest worktree: only unmerged entries
 984         * are checked out
 985         */
 986        for (i = 0; i < the_index->cache_nr; i++) {
 987                struct cache_entry *ce = the_index->cache[i];
 988
 989                if (select_flag && !(ce->ce_flags & select_flag))
 990                        continue;
 991
 992                if (!ce_stage(ce))
 993                        ce->ce_flags |= skip_wt_flag;
 994                else
 995                        ce->ce_flags &= ~skip_wt_flag;
 996        }
 997
 998        /*
 999         * 2. Widen worktree according to sparse-checkout file.
1000         * Matched entries will have skip_wt_flag cleared (i.e. "in")
1001         */
1002        clear_ce_flags(the_index->cache, the_index->cache_nr,
1003                       select_flag, skip_wt_flag, el);
1004}
1005
1006static int verify_absent(const struct cache_entry *,
1007                         enum unpack_trees_error_types,
1008                         struct unpack_trees_options *);
1009/*
1010 * N-way merge "len" trees.  Returns 0 on success, -1 on failure to manipulate the
1011 * resulting index, -2 on failure to reflect the changes to the work tree.
1012 *
1013 * CE_ADDED, CE_UNPACKED and CE_NEW_SKIP_WORKTREE are used internally
1014 */
1015int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options *o)
1016{
1017        int i, ret;
1018        static struct cache_entry *dfc;
1019        struct exclude_list el;
1020
1021        if (len > MAX_UNPACK_TREES)
1022                die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
1023        memset(&state, 0, sizeof(state));
1024        state.base_dir = "";
1025        state.force = 1;
1026        state.quiet = 1;
1027        state.refresh_cache = 1;
1028
1029        memset(&el, 0, sizeof(el));
1030        if (!core_apply_sparse_checkout || !o->update)
1031                o->skip_sparse_checkout = 1;
1032        if (!o->skip_sparse_checkout) {
1033                if (add_excludes_from_file_to_list(git_path("info/sparse-checkout"), "", 0, &el, 0) < 0)
1034                        o->skip_sparse_checkout = 1;
1035                else
1036                        o->el = &el;
1037        }
1038
1039        memset(&o->result, 0, sizeof(o->result));
1040        o->result.initialized = 1;
1041        o->result.timestamp.sec = o->src_index->timestamp.sec;
1042        o->result.timestamp.nsec = o->src_index->timestamp.nsec;
1043        o->result.version = o->src_index->version;
1044        o->merge_size = len;
1045        mark_all_ce_unused(o->src_index);
1046
1047        /*
1048         * Sparse checkout loop #1: set NEW_SKIP_WORKTREE on existing entries
1049         */
1050        if (!o->skip_sparse_checkout)
1051                mark_new_skip_worktree(o->el, o->src_index, 0, CE_NEW_SKIP_WORKTREE);
1052
1053        if (!dfc)
1054                dfc = xcalloc(1, cache_entry_size(0));
1055        o->df_conflict_entry = dfc;
1056
1057        if (len) {
1058                const char *prefix = o->prefix ? o->prefix : "";
1059                struct traverse_info info;
1060
1061                setup_traverse_info(&info, prefix);
1062                info.fn = unpack_callback;
1063                info.data = o;
1064                info.show_all_errors = o->show_all_errors;
1065                info.pathspec = o->pathspec;
1066
1067                if (o->prefix) {
1068                        /*
1069                         * Unpack existing index entries that sort before the
1070                         * prefix the tree is spliced into.  Note that o->merge
1071                         * is always true in this case.
1072                         */
1073                        while (1) {
1074                                struct cache_entry *ce = next_cache_entry(o);
1075                                if (!ce)
1076                                        break;
1077                                if (ce_in_traverse_path(ce, &info))
1078                                        break;
1079                                if (unpack_index_entry(ce, o) < 0)
1080                                        goto return_failed;
1081                        }
1082                }
1083
1084                if (traverse_trees(len, t, &info) < 0)
1085                        goto return_failed;
1086        }
1087
1088        /* Any left-over entries in the index? */
1089        if (o->merge) {
1090                while (1) {
1091                        struct cache_entry *ce = next_cache_entry(o);
1092                        if (!ce)
1093                                break;
1094                        if (unpack_index_entry(ce, o) < 0)
1095                                goto return_failed;
1096                }
1097        }
1098        mark_all_ce_unused(o->src_index);
1099
1100        if (o->trivial_merges_only && o->nontrivial_merge) {
1101                ret = unpack_failed(o, "Merge requires file-level merging");
1102                goto done;
1103        }
1104
1105        if (!o->skip_sparse_checkout) {
1106                int empty_worktree = 1;
1107
1108                /*
1109                 * Sparse checkout loop #2: set NEW_SKIP_WORKTREE on entries not in loop #1
1110                 * If the will have NEW_SKIP_WORKTREE, also set CE_SKIP_WORKTREE
1111                 * so apply_sparse_checkout() won't attempt to remove it from worktree
1112                 */
1113                mark_new_skip_worktree(o->el, &o->result, CE_ADDED, CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1114
1115                ret = 0;
1116                for (i = 0; i < o->result.cache_nr; i++) {
1117                        struct cache_entry *ce = o->result.cache[i];
1118
1119                        /*
1120                         * Entries marked with CE_ADDED in merged_entry() do not have
1121                         * verify_absent() check (the check is effectively disabled
1122                         * because CE_NEW_SKIP_WORKTREE is set unconditionally).
1123                         *
1124                         * Do the real check now because we have had
1125                         * correct CE_NEW_SKIP_WORKTREE
1126                         */
1127                        if (ce->ce_flags & CE_ADDED &&
1128                            verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1129                                if (!o->show_all_errors)
1130                                        goto return_failed;
1131                                ret = -1;
1132                        }
1133
1134                        if (apply_sparse_checkout(ce, o)) {
1135                                if (!o->show_all_errors)
1136                                        goto return_failed;
1137                                ret = -1;
1138                        }
1139                        if (!ce_skip_worktree(ce))
1140                                empty_worktree = 0;
1141
1142                }
1143                if (ret < 0)
1144                        goto return_failed;
1145                /*
1146                 * Sparse checkout is meant to narrow down checkout area
1147                 * but it does not make sense to narrow down to empty working
1148                 * tree. This is usually a mistake in sparse checkout rules.
1149                 * Do not allow users to do that.
1150                 */
1151                if (o->result.cache_nr && empty_worktree) {
1152                        ret = unpack_failed(o, "Sparse checkout leaves no entry on working directory");
1153                        goto done;
1154                }
1155        }
1156
1157        o->src_index = NULL;
1158        ret = check_updates(o) ? (-2) : 0;
1159        if (o->dst_index) {
1160                discard_index(o->dst_index);
1161                *o->dst_index = o->result;
1162        }
1163
1164done:
1165        clear_exclude_list(&el);
1166        return ret;
1167
1168return_failed:
1169        if (o->show_all_errors)
1170                display_error_msgs(o);
1171        mark_all_ce_unused(o->src_index);
1172        ret = unpack_failed(o, NULL);
1173        if (o->exiting_early)
1174                ret = 0;
1175        goto done;
1176}
1177
1178/* Here come the merge functions */
1179
1180static int reject_merge(const struct cache_entry *ce,
1181                        struct unpack_trees_options *o)
1182{
1183        return add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
1184}
1185
1186static int same(const struct cache_entry *a, const struct cache_entry *b)
1187{
1188        if (!!a != !!b)
1189                return 0;
1190        if (!a && !b)
1191                return 1;
1192        if ((a->ce_flags | b->ce_flags) & CE_CONFLICTED)
1193                return 0;
1194        return a->ce_mode == b->ce_mode &&
1195               !hashcmp(a->sha1, b->sha1);
1196}
1197
1198
1199/*
1200 * When a CE gets turned into an unmerged entry, we
1201 * want it to be up-to-date
1202 */
1203static int verify_uptodate_1(const struct cache_entry *ce,
1204                             struct unpack_trees_options *o,
1205                             enum unpack_trees_error_types error_type)
1206{
1207        struct stat st;
1208
1209        if (o->index_only)
1210                return 0;
1211
1212        /*
1213         * CE_VALID and CE_SKIP_WORKTREE cheat, we better check again
1214         * if this entry is truly up-to-date because this file may be
1215         * overwritten.
1216         */
1217        if ((ce->ce_flags & CE_VALID) || ce_skip_worktree(ce))
1218                ; /* keep checking */
1219        else if (o->reset || ce_uptodate(ce))
1220                return 0;
1221
1222        if (!lstat(ce->name, &st)) {
1223                int flags = CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE;
1224                unsigned changed = ie_match_stat(o->src_index, ce, &st, flags);
1225                if (!changed)
1226                        return 0;
1227                /*
1228                 * NEEDSWORK: the current default policy is to allow
1229                 * submodule to be out of sync wrt the superproject
1230                 * index.  This needs to be tightened later for
1231                 * submodules that are marked to be automatically
1232                 * checked out.
1233                 */
1234                if (S_ISGITLINK(ce->ce_mode))
1235                        return 0;
1236                errno = 0;
1237        }
1238        if (errno == ENOENT)
1239                return 0;
1240        return o->gently ? -1 :
1241                add_rejected_path(o, error_type, ce->name);
1242}
1243
1244static int verify_uptodate(const struct cache_entry *ce,
1245                           struct unpack_trees_options *o)
1246{
1247        if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1248                return 0;
1249        return verify_uptodate_1(ce, o, ERROR_NOT_UPTODATE_FILE);
1250}
1251
1252static int verify_uptodate_sparse(const struct cache_entry *ce,
1253                                  struct unpack_trees_options *o)
1254{
1255        return verify_uptodate_1(ce, o, ERROR_SPARSE_NOT_UPTODATE_FILE);
1256}
1257
1258static void invalidate_ce_path(const struct cache_entry *ce,
1259                               struct unpack_trees_options *o)
1260{
1261        if (ce)
1262                cache_tree_invalidate_path(o->src_index->cache_tree, ce->name);
1263}
1264
1265/*
1266 * Check that checking out ce->sha1 in subdir ce->name is not
1267 * going to overwrite any working files.
1268 *
1269 * Currently, git does not checkout subprojects during a superproject
1270 * checkout, so it is not going to overwrite anything.
1271 */
1272static int verify_clean_submodule(const struct cache_entry *ce,
1273                                  enum unpack_trees_error_types error_type,
1274                                  struct unpack_trees_options *o)
1275{
1276        return 0;
1277}
1278
1279static int verify_clean_subdirectory(const struct cache_entry *ce,
1280                                     enum unpack_trees_error_types error_type,
1281                                     struct unpack_trees_options *o)
1282{
1283        /*
1284         * we are about to extract "ce->name"; we would not want to lose
1285         * anything in the existing directory there.
1286         */
1287        int namelen;
1288        int i;
1289        struct dir_struct d;
1290        char *pathbuf;
1291        int cnt = 0;
1292        unsigned char sha1[20];
1293
1294        if (S_ISGITLINK(ce->ce_mode) &&
1295            resolve_gitlink_ref(ce->name, "HEAD", sha1) == 0) {
1296                /* If we are not going to update the submodule, then
1297                 * we don't care.
1298                 */
1299                if (!hashcmp(sha1, ce->sha1))
1300                        return 0;
1301                return verify_clean_submodule(ce, error_type, o);
1302        }
1303
1304        /*
1305         * First let's make sure we do not have a local modification
1306         * in that directory.
1307         */
1308        namelen = ce_namelen(ce);
1309        for (i = locate_in_src_index(ce, o);
1310             i < o->src_index->cache_nr;
1311             i++) {
1312                struct cache_entry *ce2 = o->src_index->cache[i];
1313                int len = ce_namelen(ce2);
1314                if (len < namelen ||
1315                    strncmp(ce->name, ce2->name, namelen) ||
1316                    ce2->name[namelen] != '/')
1317                        break;
1318                /*
1319                 * ce2->name is an entry in the subdirectory to be
1320                 * removed.
1321                 */
1322                if (!ce_stage(ce2)) {
1323                        if (verify_uptodate(ce2, o))
1324                                return -1;
1325                        add_entry(o, ce2, CE_REMOVE, 0);
1326                        mark_ce_used(ce2, o);
1327                }
1328                cnt++;
1329        }
1330
1331        /*
1332         * Then we need to make sure that we do not lose a locally
1333         * present file that is not ignored.
1334         */
1335        pathbuf = xmalloc(namelen + 2);
1336        memcpy(pathbuf, ce->name, namelen);
1337        strcpy(pathbuf+namelen, "/");
1338
1339        memset(&d, 0, sizeof(d));
1340        if (o->dir)
1341                d.exclude_per_dir = o->dir->exclude_per_dir;
1342        i = read_directory(&d, pathbuf, namelen+1, NULL);
1343        if (i)
1344                return o->gently ? -1 :
1345                        add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
1346        free(pathbuf);
1347        return cnt;
1348}
1349
1350/*
1351 * This gets called when there was no index entry for the tree entry 'dst',
1352 * but we found a file in the working tree that 'lstat()' said was fine,
1353 * and we're on a case-insensitive filesystem.
1354 *
1355 * See if we can find a case-insensitive match in the index that also
1356 * matches the stat information, and assume it's that other file!
1357 */
1358static int icase_exists(struct unpack_trees_options *o, const char *name, int len, struct stat *st)
1359{
1360        const struct cache_entry *src;
1361
1362        src = index_file_exists(o->src_index, name, len, 1);
1363        return src && !ie_match_stat(o->src_index, src, st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
1364}
1365
1366static int check_ok_to_remove(const char *name, int len, int dtype,
1367                              const struct cache_entry *ce, struct stat *st,
1368                              enum unpack_trees_error_types error_type,
1369                              struct unpack_trees_options *o)
1370{
1371        const struct cache_entry *result;
1372
1373        /*
1374         * It may be that the 'lstat()' succeeded even though
1375         * target 'ce' was absent, because there is an old
1376         * entry that is different only in case..
1377         *
1378         * Ignore that lstat() if it matches.
1379         */
1380        if (ignore_case && icase_exists(o, name, len, st))
1381                return 0;
1382
1383        if (o->dir &&
1384            is_excluded(o->dir, name, &dtype))
1385                /*
1386                 * ce->name is explicitly excluded, so it is Ok to
1387                 * overwrite it.
1388                 */
1389                return 0;
1390        if (S_ISDIR(st->st_mode)) {
1391                /*
1392                 * We are checking out path "foo" and
1393                 * found "foo/." in the working tree.
1394                 * This is tricky -- if we have modified
1395                 * files that are in "foo/" we would lose
1396                 * them.
1397                 */
1398                if (verify_clean_subdirectory(ce, error_type, o) < 0)
1399                        return -1;
1400                return 0;
1401        }
1402
1403        /*
1404         * The previous round may already have decided to
1405         * delete this path, which is in a subdirectory that
1406         * is being replaced with a blob.
1407         */
1408        result = index_file_exists(&o->result, name, len, 0);
1409        if (result) {
1410                if (result->ce_flags & CE_REMOVE)
1411                        return 0;
1412        }
1413
1414        return o->gently ? -1 :
1415                add_rejected_path(o, error_type, name);
1416}
1417
1418/*
1419 * We do not want to remove or overwrite a working tree file that
1420 * is not tracked, unless it is ignored.
1421 */
1422static int verify_absent_1(const struct cache_entry *ce,
1423                           enum unpack_trees_error_types error_type,
1424                           struct unpack_trees_options *o)
1425{
1426        int len;
1427        struct stat st;
1428
1429        if (o->index_only || o->reset || !o->update)
1430                return 0;
1431
1432        len = check_leading_path(ce->name, ce_namelen(ce));
1433        if (!len)
1434                return 0;
1435        else if (len > 0) {
1436                char path[PATH_MAX + 1];
1437                memcpy(path, ce->name, len);
1438                path[len] = 0;
1439                if (lstat(path, &st))
1440                        return error("cannot stat '%s': %s", path,
1441                                        strerror(errno));
1442
1443                return check_ok_to_remove(path, len, DT_UNKNOWN, NULL, &st,
1444                                error_type, o);
1445        } else if (lstat(ce->name, &st)) {
1446                if (errno != ENOENT)
1447                        return error("cannot stat '%s': %s", ce->name,
1448                                     strerror(errno));
1449                return 0;
1450        } else {
1451                return check_ok_to_remove(ce->name, ce_namelen(ce),
1452                                          ce_to_dtype(ce), ce, &st,
1453                                          error_type, o);
1454        }
1455}
1456
1457static int verify_absent(const struct cache_entry *ce,
1458                         enum unpack_trees_error_types error_type,
1459                         struct unpack_trees_options *o)
1460{
1461        if (!o->skip_sparse_checkout && (ce->ce_flags & CE_NEW_SKIP_WORKTREE))
1462                return 0;
1463        return verify_absent_1(ce, error_type, o);
1464}
1465
1466static int verify_absent_sparse(const struct cache_entry *ce,
1467                                enum unpack_trees_error_types error_type,
1468                                struct unpack_trees_options *o)
1469{
1470        enum unpack_trees_error_types orphaned_error = error_type;
1471        if (orphaned_error == ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN)
1472                orphaned_error = ERROR_WOULD_LOSE_ORPHANED_OVERWRITTEN;
1473
1474        return verify_absent_1(ce, orphaned_error, o);
1475}
1476
1477static int merged_entry(const struct cache_entry *ce,
1478                        const struct cache_entry *old,
1479                        struct unpack_trees_options *o)
1480{
1481        int update = CE_UPDATE;
1482        struct cache_entry *merge = dup_entry(ce);
1483
1484        if (!old) {
1485                /*
1486                 * New index entries. In sparse checkout, the following
1487                 * verify_absent() will be delayed until after
1488                 * traverse_trees() finishes in unpack_trees(), then:
1489                 *
1490                 *  - CE_NEW_SKIP_WORKTREE will be computed correctly
1491                 *  - verify_absent() be called again, this time with
1492                 *    correct CE_NEW_SKIP_WORKTREE
1493                 *
1494                 * verify_absent() call here does nothing in sparse
1495                 * checkout (i.e. o->skip_sparse_checkout == 0)
1496                 */
1497                update |= CE_ADDED;
1498                merge->ce_flags |= CE_NEW_SKIP_WORKTREE;
1499
1500                if (verify_absent(merge,
1501                                  ERROR_WOULD_LOSE_UNTRACKED_OVERWRITTEN, o)) {
1502                        free(merge);
1503                        return -1;
1504                }
1505                invalidate_ce_path(merge, o);
1506        } else if (!(old->ce_flags & CE_CONFLICTED)) {
1507                /*
1508                 * See if we can re-use the old CE directly?
1509                 * That way we get the uptodate stat info.
1510                 *
1511                 * This also removes the UPDATE flag on a match; otherwise
1512                 * we will end up overwriting local changes in the work tree.
1513                 */
1514                if (same(old, merge)) {
1515                        copy_cache_entry(merge, old);
1516                        update = 0;
1517                } else {
1518                        if (verify_uptodate(old, o)) {
1519                                free(merge);
1520                                return -1;
1521                        }
1522                        /* Migrate old flags over */
1523                        update |= old->ce_flags & (CE_SKIP_WORKTREE | CE_NEW_SKIP_WORKTREE);
1524                        invalidate_ce_path(old, o);
1525                }
1526        } else {
1527                /*
1528                 * Previously unmerged entry left as an existence
1529                 * marker by read_index_unmerged();
1530                 */
1531                invalidate_ce_path(old, o);
1532        }
1533
1534        do_add_entry(o, merge, update, CE_STAGEMASK);
1535        return 1;
1536}
1537
1538static int deleted_entry(const struct cache_entry *ce,
1539                         const struct cache_entry *old,
1540                         struct unpack_trees_options *o)
1541{
1542        /* Did it exist in the index? */
1543        if (!old) {
1544                if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1545                        return -1;
1546                return 0;
1547        }
1548        if (!(old->ce_flags & CE_CONFLICTED) && verify_uptodate(old, o))
1549                return -1;
1550        add_entry(o, ce, CE_REMOVE, 0);
1551        invalidate_ce_path(ce, o);
1552        return 1;
1553}
1554
1555static int keep_entry(const struct cache_entry *ce,
1556                      struct unpack_trees_options *o)
1557{
1558        add_entry(o, ce, 0, 0);
1559        return 1;
1560}
1561
1562#if DBRT_DEBUG
1563static void show_stage_entry(FILE *o,
1564                             const char *label, const struct cache_entry *ce)
1565{
1566        if (!ce)
1567                fprintf(o, "%s (missing)\n", label);
1568        else
1569                fprintf(o, "%s%06o %s %d\t%s\n",
1570                        label,
1571                        ce->ce_mode,
1572                        sha1_to_hex(ce->sha1),
1573                        ce_stage(ce),
1574                        ce->name);
1575}
1576#endif
1577
1578int threeway_merge(const struct cache_entry * const *stages,
1579                   struct unpack_trees_options *o)
1580{
1581        const struct cache_entry *index;
1582        const struct cache_entry *head;
1583        const struct cache_entry *remote = stages[o->head_idx + 1];
1584        int count;
1585        int head_match = 0;
1586        int remote_match = 0;
1587
1588        int df_conflict_head = 0;
1589        int df_conflict_remote = 0;
1590
1591        int any_anc_missing = 0;
1592        int no_anc_exists = 1;
1593        int i;
1594
1595        for (i = 1; i < o->head_idx; i++) {
1596                if (!stages[i] || stages[i] == o->df_conflict_entry)
1597                        any_anc_missing = 1;
1598                else
1599                        no_anc_exists = 0;
1600        }
1601
1602        index = stages[0];
1603        head = stages[o->head_idx];
1604
1605        if (head == o->df_conflict_entry) {
1606                df_conflict_head = 1;
1607                head = NULL;
1608        }
1609
1610        if (remote == o->df_conflict_entry) {
1611                df_conflict_remote = 1;
1612                remote = NULL;
1613        }
1614
1615        /*
1616         * First, if there's a #16 situation, note that to prevent #13
1617         * and #14.
1618         */
1619        if (!same(remote, head)) {
1620                for (i = 1; i < o->head_idx; i++) {
1621                        if (same(stages[i], head)) {
1622                                head_match = i;
1623                        }
1624                        if (same(stages[i], remote)) {
1625                                remote_match = i;
1626                        }
1627                }
1628        }
1629
1630        /*
1631         * We start with cases where the index is allowed to match
1632         * something other than the head: #14(ALT) and #2ALT, where it
1633         * is permitted to match the result instead.
1634         */
1635        /* #14, #14ALT, #2ALT */
1636        if (remote && !df_conflict_head && head_match && !remote_match) {
1637                if (index && !same(index, remote) && !same(index, head))
1638                        return o->gently ? -1 : reject_merge(index, o);
1639                return merged_entry(remote, index, o);
1640        }
1641        /*
1642         * If we have an entry in the index cache, then we want to
1643         * make sure that it matches head.
1644         */
1645        if (index && !same(index, head))
1646                return o->gently ? -1 : reject_merge(index, o);
1647
1648        if (head) {
1649                /* #5ALT, #15 */
1650                if (same(head, remote))
1651                        return merged_entry(head, index, o);
1652                /* #13, #3ALT */
1653                if (!df_conflict_remote && remote_match && !head_match)
1654                        return merged_entry(head, index, o);
1655        }
1656
1657        /* #1 */
1658        if (!head && !remote && any_anc_missing)
1659                return 0;
1660
1661        /*
1662         * Under the "aggressive" rule, we resolve mostly trivial
1663         * cases that we historically had git-merge-one-file resolve.
1664         */
1665        if (o->aggressive) {
1666                int head_deleted = !head;
1667                int remote_deleted = !remote;
1668                const struct cache_entry *ce = NULL;
1669
1670                if (index)
1671                        ce = index;
1672                else if (head)
1673                        ce = head;
1674                else if (remote)
1675                        ce = remote;
1676                else {
1677                        for (i = 1; i < o->head_idx; i++) {
1678                                if (stages[i] && stages[i] != o->df_conflict_entry) {
1679                                        ce = stages[i];
1680                                        break;
1681                                }
1682                        }
1683                }
1684
1685                /*
1686                 * Deleted in both.
1687                 * Deleted in one and unchanged in the other.
1688                 */
1689                if ((head_deleted && remote_deleted) ||
1690                    (head_deleted && remote && remote_match) ||
1691                    (remote_deleted && head && head_match)) {
1692                        if (index)
1693                                return deleted_entry(index, index, o);
1694                        if (ce && !head_deleted) {
1695                                if (verify_absent(ce, ERROR_WOULD_LOSE_UNTRACKED_REMOVED, o))
1696                                        return -1;
1697                        }
1698                        return 0;
1699                }
1700                /*
1701                 * Added in both, identically.
1702                 */
1703                if (no_anc_exists && head && remote && same(head, remote))
1704                        return merged_entry(head, index, o);
1705
1706        }
1707
1708        /* Below are "no merge" cases, which require that the index be
1709         * up-to-date to avoid the files getting overwritten with
1710         * conflict resolution files.
1711         */
1712        if (index) {
1713                if (verify_uptodate(index, o))
1714                        return -1;
1715        }
1716
1717        o->nontrivial_merge = 1;
1718
1719        /* #2, #3, #4, #6, #7, #9, #10, #11. */
1720        count = 0;
1721        if (!head_match || !remote_match) {
1722                for (i = 1; i < o->head_idx; i++) {
1723                        if (stages[i] && stages[i] != o->df_conflict_entry) {
1724                                keep_entry(stages[i], o);
1725                                count++;
1726                                break;
1727                        }
1728                }
1729        }
1730#if DBRT_DEBUG
1731        else {
1732                fprintf(stderr, "read-tree: warning #16 detected\n");
1733                show_stage_entry(stderr, "head   ", stages[head_match]);
1734                show_stage_entry(stderr, "remote ", stages[remote_match]);
1735        }
1736#endif
1737        if (head) { count += keep_entry(head, o); }
1738        if (remote) { count += keep_entry(remote, o); }
1739        return count;
1740}
1741
1742/*
1743 * Two-way merge.
1744 *
1745 * The rule is to "carry forward" what is in the index without losing
1746 * information across a "fast-forward", favoring a successful merge
1747 * over a merge failure when it makes sense.  For details of the
1748 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
1749 *
1750 */
1751int twoway_merge(const struct cache_entry * const *src,
1752                 struct unpack_trees_options *o)
1753{
1754        const struct cache_entry *current = src[0];
1755        const struct cache_entry *oldtree = src[1];
1756        const struct cache_entry *newtree = src[2];
1757
1758        if (o->merge_size != 2)
1759                return error("Cannot do a twoway merge of %d trees",
1760                             o->merge_size);
1761
1762        if (oldtree == o->df_conflict_entry)
1763                oldtree = NULL;
1764        if (newtree == o->df_conflict_entry)
1765                newtree = NULL;
1766
1767        if (current) {
1768                if (current->ce_flags & CE_CONFLICTED) {
1769                        if (same(oldtree, newtree) || o->reset) {
1770                                if (!newtree)
1771                                        return deleted_entry(current, current, o);
1772                                else
1773                                        return merged_entry(newtree, current, o);
1774                        }
1775                        return o->gently ? -1 : reject_merge(current, o);
1776                }
1777                else if ((!oldtree && !newtree) || /* 4 and 5 */
1778                         (!oldtree && newtree &&
1779                          same(current, newtree)) || /* 6 and 7 */
1780                         (oldtree && newtree &&
1781                          same(oldtree, newtree)) || /* 14 and 15 */
1782                         (oldtree && newtree &&
1783                          !same(oldtree, newtree) && /* 18 and 19 */
1784                          same(current, newtree))) {
1785                        return keep_entry(current, o);
1786                }
1787                else if (oldtree && !newtree && same(current, oldtree)) {
1788                        /* 10 or 11 */
1789                        return deleted_entry(oldtree, current, o);
1790                }
1791                else if (oldtree && newtree &&
1792                         same(current, oldtree) && !same(current, newtree)) {
1793                        /* 20 or 21 */
1794                        return merged_entry(newtree, current, o);
1795                }
1796                else {
1797                        /* all other failures */
1798                        if (oldtree)
1799                                return o->gently ? -1 : reject_merge(oldtree, o);
1800                        if (current)
1801                                return o->gently ? -1 : reject_merge(current, o);
1802                        if (newtree)
1803                                return o->gently ? -1 : reject_merge(newtree, o);
1804                        return -1;
1805                }
1806        }
1807        else if (newtree) {
1808                if (oldtree && !o->initial_checkout) {
1809                        /*
1810                         * deletion of the path was staged;
1811                         */
1812                        if (same(oldtree, newtree))
1813                                return 1;
1814                        return reject_merge(oldtree, o);
1815                }
1816                return merged_entry(newtree, current, o);
1817        }
1818        return deleted_entry(oldtree, current, o);
1819}
1820
1821/*
1822 * Bind merge.
1823 *
1824 * Keep the index entries at stage0, collapse stage1 but make sure
1825 * stage0 does not have anything there.
1826 */
1827int bind_merge(const struct cache_entry * const *src,
1828               struct unpack_trees_options *o)
1829{
1830        const struct cache_entry *old = src[0];
1831        const struct cache_entry *a = src[1];
1832
1833        if (o->merge_size != 1)
1834                return error("Cannot do a bind merge of %d trees",
1835                             o->merge_size);
1836        if (a && old)
1837                return o->gently ? -1 :
1838                        error(ERRORMSG(o, ERROR_BIND_OVERLAP), a->name, old->name);
1839        if (!a)
1840                return keep_entry(old, o);
1841        else
1842                return merged_entry(a, NULL, o);
1843}
1844
1845/*
1846 * One-way merge.
1847 *
1848 * The rule is:
1849 * - take the stat information from stage0, take the data from stage1
1850 */
1851int oneway_merge(const struct cache_entry * const *src,
1852                 struct unpack_trees_options *o)
1853{
1854        const struct cache_entry *old = src[0];
1855        const struct cache_entry *a = src[1];
1856
1857        if (o->merge_size != 1)
1858                return error("Cannot do a oneway merge of %d trees",
1859                             o->merge_size);
1860
1861        if (!a || a == o->df_conflict_entry)
1862                return deleted_entry(old, old, o);
1863
1864        if (old && same(old, a)) {
1865                int update = 0;
1866                if (o->reset && o->update && !ce_uptodate(old) && !ce_skip_worktree(old)) {
1867                        struct stat st;
1868                        if (lstat(old->name, &st) ||
1869                            ie_match_stat(o->src_index, old, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE))
1870                                update |= CE_UPDATE;
1871                }
1872                add_entry(o, old, update, 0);
1873                return 0;
1874        }
1875        return merged_entry(a, old, o);
1876}