Andrew's git / gitweb.git / builtin-read-tree.c
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builtin-read-tree.con commit Fix more typos, primarily in the code (82e5a82)
   1/*
   2 * GIT - The information manager from hell
   3 *
   4 * Copyright (C) Linus Torvalds, 2005
   5 */
   6#define DBRT_DEBUG 1
   7
   8#include "cache.h"
   9
  10#include "object.h"
  11#include "tree.h"
  12#include "tree-walk.h"
  13#include "cache-tree.h"
  14#include <sys/time.h>
  15#include <signal.h>
  16#include "builtin.h"
  17
  18static int reset = 0;
  19static int merge = 0;
  20static int update = 0;
  21static int index_only = 0;
  22static int nontrivial_merge = 0;
  23static int trivial_merges_only = 0;
  24static int aggressive = 0;
  25static int verbose_update = 0;
  26static volatile int progress_update = 0;
  27static const char *prefix = NULL;
  28
  29static int head_idx = -1;
  30static int merge_size = 0;
  31
  32static struct object_list *trees = NULL;
  33
  34static struct cache_entry df_conflict_entry;
  35
  36struct tree_entry_list {
  37        struct tree_entry_list *next;
  38        unsigned directory : 1;
  39        unsigned executable : 1;
  40        unsigned symlink : 1;
  41        unsigned int mode;
  42        const char *name;
  43        const unsigned char *sha1;
  44};
  45
  46static struct tree_entry_list df_conflict_list;
  47
  48typedef int (*merge_fn_t)(struct cache_entry **src);
  49
  50static struct tree_entry_list *create_tree_entry_list(struct tree *tree)
  51{
  52        struct tree_desc desc;
  53        struct name_entry one;
  54        struct tree_entry_list *ret = NULL;
  55        struct tree_entry_list **list_p = &ret;
  56
  57        desc.buf = tree->buffer;
  58        desc.size = tree->size;
  59
  60        while (tree_entry(&desc, &one)) {
  61                struct tree_entry_list *entry;
  62
  63                entry = xmalloc(sizeof(struct tree_entry_list));
  64                entry->name = one.path;
  65                entry->sha1 = one.sha1;
  66                entry->mode = one.mode;
  67                entry->directory = S_ISDIR(one.mode) != 0;
  68                entry->executable = (one.mode & S_IXUSR) != 0;
  69                entry->symlink = S_ISLNK(one.mode) != 0;
  70                entry->next = NULL;
  71
  72                *list_p = entry;
  73                list_p = &entry->next;
  74        }
  75        return ret;
  76}
  77
  78static int entcmp(const char *name1, int dir1, const char *name2, int dir2)
  79{
  80        int len1 = strlen(name1);
  81        int len2 = strlen(name2);
  82        int len = len1 < len2 ? len1 : len2;
  83        int ret = memcmp(name1, name2, len);
  84        unsigned char c1, c2;
  85        if (ret)
  86                return ret;
  87        c1 = name1[len];
  88        c2 = name2[len];
  89        if (!c1 && dir1)
  90                c1 = '/';
  91        if (!c2 && dir2)
  92                c2 = '/';
  93        ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
  94        if (c1 && c2 && !ret)
  95                ret = len1 - len2;
  96        return ret;
  97}
  98
  99static int unpack_trees_rec(struct tree_entry_list **posns, int len,
 100                            const char *base, merge_fn_t fn, int *indpos)
 101{
 102        int baselen = strlen(base);
 103        int src_size = len + 1;
 104        do {
 105                int i;
 106                const char *first;
 107                int firstdir = 0;
 108                int pathlen;
 109                unsigned ce_size;
 110                struct tree_entry_list **subposns;
 111                struct cache_entry **src;
 112                int any_files = 0;
 113                int any_dirs = 0;
 114                char *cache_name;
 115                int ce_stage;
 116
 117                /* Find the first name in the input. */
 118
 119                first = NULL;
 120                cache_name = NULL;
 121
 122                /* Check the cache */
 123                if (merge && *indpos < active_nr) {
 124                        /* This is a bit tricky: */
 125                        /* If the index has a subdirectory (with
 126                         * contents) as the first name, it'll get a
 127                         * filename like "foo/bar". But that's after
 128                         * "foo", so the entry in trees will get
 129                         * handled first, at which point we'll go into
 130                         * "foo", and deal with "bar" from the index,
 131                         * because the base will be "foo/". The only
 132                         * way we can actually have "foo/bar" first of
 133                         * all the things is if the trees don't
 134                         * contain "foo" at all, in which case we'll
 135                         * handle "foo/bar" without going into the
 136                         * directory, but that's fine (and will return
 137                         * an error anyway, with the added unknown
 138                         * file case.
 139                         */
 140
 141                        cache_name = active_cache[*indpos]->name;
 142                        if (strlen(cache_name) > baselen &&
 143                            !memcmp(cache_name, base, baselen)) {
 144                                cache_name += baselen;
 145                                first = cache_name;
 146                        } else {
 147                                cache_name = NULL;
 148                        }
 149                }
 150
 151#if DBRT_DEBUG > 1
 152                if (first)
 153                        printf("index %s\n", first);
 154#endif
 155                for (i = 0; i < len; i++) {
 156                        if (!posns[i] || posns[i] == &df_conflict_list)
 157                                continue;
 158#if DBRT_DEBUG > 1
 159                        printf("%d %s\n", i + 1, posns[i]->name);
 160#endif
 161                        if (!first || entcmp(first, firstdir,
 162                                             posns[i]->name, 
 163                                             posns[i]->directory) > 0) {
 164                                first = posns[i]->name;
 165                                firstdir = posns[i]->directory;
 166                        }
 167                }
 168                /* No name means we're done */
 169                if (!first)
 170                        return 0;
 171
 172                pathlen = strlen(first);
 173                ce_size = cache_entry_size(baselen + pathlen);
 174
 175                src = xcalloc(src_size, sizeof(struct cache_entry *));
 176
 177                subposns = xcalloc(len, sizeof(struct tree_list_entry *));
 178
 179                if (cache_name && !strcmp(cache_name, first)) {
 180                        any_files = 1;
 181                        src[0] = active_cache[*indpos];
 182                        remove_cache_entry_at(*indpos);
 183                }
 184
 185                for (i = 0; i < len; i++) {
 186                        struct cache_entry *ce;
 187
 188                        if (!posns[i] ||
 189                            (posns[i] != &df_conflict_list &&
 190                             strcmp(first, posns[i]->name))) {
 191                                continue;
 192                        }
 193
 194                        if (posns[i] == &df_conflict_list) {
 195                                src[i + merge] = &df_conflict_entry;
 196                                continue;
 197                        }
 198
 199                        if (posns[i]->directory) {
 200                                struct tree *tree = lookup_tree(posns[i]->sha1);
 201                                any_dirs = 1;
 202                                parse_tree(tree);
 203                                subposns[i] = create_tree_entry_list(tree);
 204                                posns[i] = posns[i]->next;
 205                                src[i + merge] = &df_conflict_entry;
 206                                continue;
 207                        }
 208
 209                        if (!merge)
 210                                ce_stage = 0;
 211                        else if (i + 1 < head_idx)
 212                                ce_stage = 1;
 213                        else if (i + 1 > head_idx)
 214                                ce_stage = 3;
 215                        else
 216                                ce_stage = 2;
 217
 218                        ce = xcalloc(1, ce_size);
 219                        ce->ce_mode = create_ce_mode(posns[i]->mode);
 220                        ce->ce_flags = create_ce_flags(baselen + pathlen,
 221                                                       ce_stage);
 222                        memcpy(ce->name, base, baselen);
 223                        memcpy(ce->name + baselen, first, pathlen + 1);
 224
 225                        any_files = 1;
 226
 227                        memcpy(ce->sha1, posns[i]->sha1, 20);
 228                        src[i + merge] = ce;
 229                        subposns[i] = &df_conflict_list;
 230                        posns[i] = posns[i]->next;
 231                }
 232                if (any_files) {
 233                        if (merge) {
 234                                int ret;
 235
 236#if DBRT_DEBUG > 1
 237                                printf("%s:\n", first);
 238                                for (i = 0; i < src_size; i++) {
 239                                        printf(" %d ", i);
 240                                        if (src[i])
 241                                                printf("%s\n", sha1_to_hex(src[i]->sha1));
 242                                        else
 243                                                printf("\n");
 244                                }
 245#endif
 246                                ret = fn(src);
 247                                
 248#if DBRT_DEBUG > 1
 249                                printf("Added %d entries\n", ret);
 250#endif
 251                                *indpos += ret;
 252                        } else {
 253                                for (i = 0; i < src_size; i++) {
 254                                        if (src[i]) {
 255                                                add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
 256                                        }
 257                                }
 258                        }
 259                }
 260                if (any_dirs) {
 261                        char *newbase = xmalloc(baselen + 2 + pathlen);
 262                        memcpy(newbase, base, baselen);
 263                        memcpy(newbase + baselen, first, pathlen);
 264                        newbase[baselen + pathlen] = '/';
 265                        newbase[baselen + pathlen + 1] = '\0';
 266                        if (unpack_trees_rec(subposns, len, newbase, fn,
 267                                             indpos))
 268                                return -1;
 269                        free(newbase);
 270                }
 271                free(subposns);
 272                free(src);
 273        } while (1);
 274}
 275
 276static void reject_merge(struct cache_entry *ce)
 277{
 278        die("Entry '%s' would be overwritten by merge. Cannot merge.", 
 279            ce->name);
 280}
 281
 282/* Unlink the last component and attempt to remove leading
 283 * directories, in case this unlink is the removal of the
 284 * last entry in the directory -- empty directories are removed.
 285 */
 286static void unlink_entry(char *name)
 287{
 288        char *cp, *prev;
 289
 290        if (unlink(name))
 291                return;
 292        prev = NULL;
 293        while (1) {
 294                int status;
 295                cp = strrchr(name, '/');
 296                if (prev)
 297                        *prev = '/';
 298                if (!cp)
 299                        break;
 300
 301                *cp = 0;
 302                status = rmdir(name);
 303                if (status) {
 304                        *cp = '/';
 305                        break;
 306                }
 307                prev = cp;
 308        }
 309}
 310
 311static void progress_interval(int signum)
 312{
 313        progress_update = 1;
 314}
 315
 316static void setup_progress_signal(void)
 317{
 318        struct sigaction sa;
 319        struct itimerval v;
 320
 321        memset(&sa, 0, sizeof(sa));
 322        sa.sa_handler = progress_interval;
 323        sigemptyset(&sa.sa_mask);
 324        sa.sa_flags = SA_RESTART;
 325        sigaction(SIGALRM, &sa, NULL);
 326
 327        v.it_interval.tv_sec = 1;
 328        v.it_interval.tv_usec = 0;
 329        v.it_value = v.it_interval;
 330        setitimer(ITIMER_REAL, &v, NULL);
 331}
 332
 333static struct checkout state;
 334static void check_updates(struct cache_entry **src, int nr)
 335{
 336        unsigned short mask = htons(CE_UPDATE);
 337        unsigned last_percent = 200, cnt = 0, total = 0;
 338
 339        if (update && verbose_update) {
 340                for (total = cnt = 0; cnt < nr; cnt++) {
 341                        struct cache_entry *ce = src[cnt];
 342                        if (!ce->ce_mode || ce->ce_flags & mask)
 343                                total++;
 344                }
 345
 346                /* Don't bother doing this for very small updates */
 347                if (total < 250)
 348                        total = 0;
 349
 350                if (total) {
 351                        fprintf(stderr, "Checking files out...\n");
 352                        setup_progress_signal();
 353                        progress_update = 1;
 354                }
 355                cnt = 0;
 356        }
 357
 358        while (nr--) {
 359                struct cache_entry *ce = *src++;
 360
 361                if (total) {
 362                        if (!ce->ce_mode || ce->ce_flags & mask) {
 363                                unsigned percent;
 364                                cnt++;
 365                                percent = (cnt * 100) / total;
 366                                if (percent != last_percent ||
 367                                    progress_update) {
 368                                        fprintf(stderr, "%4u%% (%u/%u) done\r",
 369                                                percent, cnt, total);
 370                                        last_percent = percent;
 371                                        progress_update = 0;
 372                                }
 373                        }
 374                }
 375                if (!ce->ce_mode) {
 376                        if (update)
 377                                unlink_entry(ce->name);
 378                        continue;
 379                }
 380                if (ce->ce_flags & mask) {
 381                        ce->ce_flags &= ~mask;
 382                        if (update)
 383                                checkout_entry(ce, &state, NULL);
 384                }
 385        }
 386        if (total) {
 387                signal(SIGALRM, SIG_IGN);
 388                fputc('\n', stderr);
 389        }
 390}
 391
 392static int unpack_trees(merge_fn_t fn)
 393{
 394        int indpos = 0;
 395        unsigned len = object_list_length(trees);
 396        struct tree_entry_list **posns;
 397        int i;
 398        struct object_list *posn = trees;
 399        merge_size = len;
 400
 401        if (len) {
 402                posns = xmalloc(len * sizeof(struct tree_entry_list *));
 403                for (i = 0; i < len; i++) {
 404                        posns[i] = create_tree_entry_list((struct tree *) posn->item);
 405                        posn = posn->next;
 406                }
 407                if (unpack_trees_rec(posns, len, prefix ? prefix : "",
 408                                     fn, &indpos))
 409                        return -1;
 410        }
 411
 412        if (trivial_merges_only && nontrivial_merge)
 413                die("Merge requires file-level merging");
 414
 415        check_updates(active_cache, active_nr);
 416        return 0;
 417}
 418
 419static int list_tree(unsigned char *sha1)
 420{
 421        struct tree *tree = parse_tree_indirect(sha1);
 422        if (!tree)
 423                return -1;
 424        object_list_append(&tree->object, &trees);
 425        return 0;
 426}
 427
 428static int same(struct cache_entry *a, struct cache_entry *b)
 429{
 430        if (!!a != !!b)
 431                return 0;
 432        if (!a && !b)
 433                return 1;
 434        return a->ce_mode == b->ce_mode && 
 435                !memcmp(a->sha1, b->sha1, 20);
 436}
 437
 438
 439/*
 440 * When a CE gets turned into an unmerged entry, we
 441 * want it to be up-to-date
 442 */
 443static void verify_uptodate(struct cache_entry *ce)
 444{
 445        struct stat st;
 446
 447        if (index_only || reset)
 448                return;
 449
 450        if (!lstat(ce->name, &st)) {
 451                unsigned changed = ce_match_stat(ce, &st, 1);
 452                if (!changed)
 453                        return;
 454                errno = 0;
 455        }
 456        if (reset) {
 457                ce->ce_flags |= htons(CE_UPDATE);
 458                return;
 459        }
 460        if (errno == ENOENT)
 461                return;
 462        die("Entry '%s' not uptodate. Cannot merge.", ce->name);
 463}
 464
 465static void invalidate_ce_path(struct cache_entry *ce)
 466{
 467        if (ce)
 468                cache_tree_invalidate_path(active_cache_tree, ce->name);
 469}
 470
 471/*
 472 * We do not want to remove or overwrite a working tree file that
 473 * is not tracked.
 474 */
 475static void verify_absent(const char *path, const char *action)
 476{
 477        struct stat st;
 478
 479        if (index_only || reset || !update)
 480                return;
 481        if (!lstat(path, &st))
 482                die("Untracked working tree file '%s' "
 483                    "would be %s by merge.", path, action);
 484}
 485
 486static int merged_entry(struct cache_entry *merge, struct cache_entry *old)
 487{
 488        merge->ce_flags |= htons(CE_UPDATE);
 489        if (old) {
 490                /*
 491                 * See if we can re-use the old CE directly?
 492                 * That way we get the uptodate stat info.
 493                 *
 494                 * This also removes the UPDATE flag on
 495                 * a match.
 496                 */
 497                if (same(old, merge)) {
 498                        *merge = *old;
 499                } else {
 500                        verify_uptodate(old);
 501                        invalidate_ce_path(old);
 502                }
 503        }
 504        else {
 505                verify_absent(merge->name, "overwritten");
 506                invalidate_ce_path(merge);
 507        }
 508
 509        merge->ce_flags &= ~htons(CE_STAGEMASK);
 510        add_cache_entry(merge, ADD_CACHE_OK_TO_ADD);
 511        return 1;
 512}
 513
 514static int deleted_entry(struct cache_entry *ce, struct cache_entry *old)
 515{
 516        if (old)
 517                verify_uptodate(old);
 518        else
 519                verify_absent(ce->name, "removed");
 520        ce->ce_mode = 0;
 521        add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
 522        invalidate_ce_path(ce);
 523        return 1;
 524}
 525
 526static int keep_entry(struct cache_entry *ce)
 527{
 528        add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
 529        return 1;
 530}
 531
 532#if DBRT_DEBUG
 533static void show_stage_entry(FILE *o,
 534                             const char *label, const struct cache_entry *ce)
 535{
 536        if (!ce)
 537                fprintf(o, "%s (missing)\n", label);
 538        else
 539                fprintf(o, "%s%06o %s %d\t%s\n",
 540                        label,
 541                        ntohl(ce->ce_mode),
 542                        sha1_to_hex(ce->sha1),
 543                        ce_stage(ce),
 544                        ce->name);
 545}
 546#endif
 547
 548static int threeway_merge(struct cache_entry **stages)
 549{
 550        struct cache_entry *index;
 551        struct cache_entry *head; 
 552        struct cache_entry *remote = stages[head_idx + 1];
 553        int count;
 554        int head_match = 0;
 555        int remote_match = 0;
 556        const char *path = NULL;
 557
 558        int df_conflict_head = 0;
 559        int df_conflict_remote = 0;
 560
 561        int any_anc_missing = 0;
 562        int no_anc_exists = 1;
 563        int i;
 564
 565        for (i = 1; i < head_idx; i++) {
 566                if (!stages[i])
 567                        any_anc_missing = 1;
 568                else {
 569                        if (!path)
 570                                path = stages[i]->name;
 571                        no_anc_exists = 0;
 572                }
 573        }
 574
 575        index = stages[0];
 576        head = stages[head_idx];
 577
 578        if (head == &df_conflict_entry) {
 579                df_conflict_head = 1;
 580                head = NULL;
 581        }
 582
 583        if (remote == &df_conflict_entry) {
 584                df_conflict_remote = 1;
 585                remote = NULL;
 586        }
 587
 588        if (!path && index)
 589                path = index->name;
 590        if (!path && head)
 591                path = head->name;
 592        if (!path && remote)
 593                path = remote->name;
 594
 595        /* First, if there's a #16 situation, note that to prevent #13
 596         * and #14.
 597         */
 598        if (!same(remote, head)) {
 599                for (i = 1; i < head_idx; i++) {
 600                        if (same(stages[i], head)) {
 601                                head_match = i;
 602                        }
 603                        if (same(stages[i], remote)) {
 604                                remote_match = i;
 605                        }
 606                }
 607        }
 608
 609        /* We start with cases where the index is allowed to match
 610         * something other than the head: #14(ALT) and #2ALT, where it
 611         * is permitted to match the result instead.
 612         */
 613        /* #14, #14ALT, #2ALT */
 614        if (remote && !df_conflict_head && head_match && !remote_match) {
 615                if (index && !same(index, remote) && !same(index, head))
 616                        reject_merge(index);
 617                return merged_entry(remote, index);
 618        }
 619        /*
 620         * If we have an entry in the index cache, then we want to
 621         * make sure that it matches head.
 622         */
 623        if (index && !same(index, head)) {
 624                reject_merge(index);
 625        }
 626
 627        if (head) {
 628                /* #5ALT, #15 */
 629                if (same(head, remote))
 630                        return merged_entry(head, index);
 631                /* #13, #3ALT */
 632                if (!df_conflict_remote && remote_match && !head_match)
 633                        return merged_entry(head, index);
 634        }
 635
 636        /* #1 */
 637        if (!head && !remote && any_anc_missing)
 638                return 0;
 639
 640        /* Under the new "aggressive" rule, we resolve mostly trivial
 641         * cases that we historically had git-merge-one-file resolve.
 642         */
 643        if (aggressive) {
 644                int head_deleted = !head && !df_conflict_head;
 645                int remote_deleted = !remote && !df_conflict_remote;
 646                /*
 647                 * Deleted in both.
 648                 * Deleted in one and unchanged in the other.
 649                 */
 650                if ((head_deleted && remote_deleted) ||
 651                    (head_deleted && remote && remote_match) ||
 652                    (remote_deleted && head && head_match)) {
 653                        if (index)
 654                                return deleted_entry(index, index);
 655                        else if (path)
 656                                verify_absent(path, "removed");
 657                        return 0;
 658                }
 659                /*
 660                 * Added in both, identically.
 661                 */
 662                if (no_anc_exists && head && remote && same(head, remote))
 663                        return merged_entry(head, index);
 664
 665        }
 666
 667        /* Below are "no merge" cases, which require that the index be
 668         * up-to-date to avoid the files getting overwritten with
 669         * conflict resolution files. 
 670         */
 671        if (index) {
 672                verify_uptodate(index);
 673        }
 674        else if (path)
 675                verify_absent(path, "overwritten");
 676
 677        nontrivial_merge = 1;
 678
 679        /* #2, #3, #4, #6, #7, #9, #11. */
 680        count = 0;
 681        if (!head_match || !remote_match) {
 682                for (i = 1; i < head_idx; i++) {
 683                        if (stages[i]) {
 684                                keep_entry(stages[i]);
 685                                count++;
 686                                break;
 687                        }
 688                }
 689        }
 690#if DBRT_DEBUG
 691        else {
 692                fprintf(stderr, "read-tree: warning #16 detected\n");
 693                show_stage_entry(stderr, "head   ", stages[head_match]);
 694                show_stage_entry(stderr, "remote ", stages[remote_match]);
 695        }
 696#endif
 697        if (head) { count += keep_entry(head); }
 698        if (remote) { count += keep_entry(remote); }
 699        return count;
 700}
 701
 702/*
 703 * Two-way merge.
 704 *
 705 * The rule is to "carry forward" what is in the index without losing
 706 * information across a "fast forward", favoring a successful merge
 707 * over a merge failure when it makes sense.  For details of the
 708 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
 709 *
 710 */
 711static int twoway_merge(struct cache_entry **src)
 712{
 713        struct cache_entry *current = src[0];
 714        struct cache_entry *oldtree = src[1], *newtree = src[2];
 715
 716        if (merge_size != 2)
 717                return error("Cannot do a twoway merge of %d trees",
 718                             merge_size);
 719
 720        if (current) {
 721                if ((!oldtree && !newtree) || /* 4 and 5 */
 722                    (!oldtree && newtree &&
 723                     same(current, newtree)) || /* 6 and 7 */
 724                    (oldtree && newtree &&
 725                     same(oldtree, newtree)) || /* 14 and 15 */
 726                    (oldtree && newtree &&
 727                     !same(oldtree, newtree) && /* 18 and 19*/
 728                     same(current, newtree))) {
 729                        return keep_entry(current);
 730                }
 731                else if (oldtree && !newtree && same(current, oldtree)) {
 732                        /* 10 or 11 */
 733                        return deleted_entry(oldtree, current);
 734                }
 735                else if (oldtree && newtree &&
 736                         same(current, oldtree) && !same(current, newtree)) {
 737                        /* 20 or 21 */
 738                        return merged_entry(newtree, current);
 739                }
 740                else {
 741                        /* all other failures */
 742                        if (oldtree)
 743                                reject_merge(oldtree);
 744                        if (current)
 745                                reject_merge(current);
 746                        if (newtree)
 747                                reject_merge(newtree);
 748                        return -1;
 749                }
 750        }
 751        else if (newtree)
 752                return merged_entry(newtree, current);
 753        else
 754                return deleted_entry(oldtree, current);
 755}
 756
 757/*
 758 * Bind merge.
 759 *
 760 * Keep the index entries at stage0, collapse stage1 but make sure
 761 * stage0 does not have anything there.
 762 */
 763static int bind_merge(struct cache_entry **src)
 764{
 765        struct cache_entry *old = src[0];
 766        struct cache_entry *a = src[1];
 767
 768        if (merge_size != 1)
 769                return error("Cannot do a bind merge of %d trees\n",
 770                             merge_size);
 771        if (a && old)
 772                die("Entry '%s' overlaps.  Cannot bind.", a->name);
 773        if (!a)
 774                return keep_entry(old);
 775        else
 776                return merged_entry(a, NULL);
 777}
 778
 779/*
 780 * One-way merge.
 781 *
 782 * The rule is:
 783 * - take the stat information from stage0, take the data from stage1
 784 */
 785static int oneway_merge(struct cache_entry **src)
 786{
 787        struct cache_entry *old = src[0];
 788        struct cache_entry *a = src[1];
 789
 790        if (merge_size != 1)
 791                return error("Cannot do a oneway merge of %d trees",
 792                             merge_size);
 793
 794        if (!a)
 795                return deleted_entry(old, old);
 796        if (old && same(old, a)) {
 797                if (reset) {
 798                        struct stat st;
 799                        if (lstat(old->name, &st) ||
 800                            ce_match_stat(old, &st, 1))
 801                                old->ce_flags |= htons(CE_UPDATE);
 802                }
 803                return keep_entry(old);
 804        }
 805        return merged_entry(a, old);
 806}
 807
 808static int read_cache_unmerged(void)
 809{
 810        int i;
 811        struct cache_entry **dst;
 812        struct cache_entry *last = NULL;
 813
 814        read_cache();
 815        dst = active_cache;
 816        for (i = 0; i < active_nr; i++) {
 817                struct cache_entry *ce = active_cache[i];
 818                if (ce_stage(ce)) {
 819                        if (last && !strcmp(ce->name, last->name))
 820                                continue;
 821                        invalidate_ce_path(ce);
 822                        last = ce;
 823                        ce->ce_mode = 0;
 824                        ce->ce_flags &= ~htons(CE_STAGEMASK);
 825                }
 826                *dst++ = ce;
 827        }
 828        active_nr = dst - active_cache;
 829        return !!last;
 830}
 831
 832static void prime_cache_tree_rec(struct cache_tree *it, struct tree *tree)
 833{
 834        struct tree_desc desc;
 835        struct name_entry entry;
 836        int cnt;
 837
 838        memcpy(it->sha1, tree->object.sha1, 20);
 839        desc.buf = tree->buffer;
 840        desc.size = tree->size;
 841        cnt = 0;
 842        while (tree_entry(&desc, &entry)) {
 843                if (!S_ISDIR(entry.mode))
 844                        cnt++;
 845                else {
 846                        struct cache_tree_sub *sub;
 847                        struct tree *subtree = lookup_tree(entry.sha1);
 848                        if (!subtree->object.parsed)
 849                                parse_tree(subtree);
 850                        sub = cache_tree_sub(it, entry.path);
 851                        sub->cache_tree = cache_tree();
 852                        prime_cache_tree_rec(sub->cache_tree, subtree);
 853                        cnt += sub->cache_tree->entry_count;
 854                }
 855        }
 856        it->entry_count = cnt;
 857}
 858
 859static void prime_cache_tree(void)
 860{
 861        struct tree *tree = (struct tree *)trees->item;
 862        if (!tree)
 863                return;
 864        active_cache_tree = cache_tree();
 865        prime_cache_tree_rec(active_cache_tree, tree);
 866
 867}
 868
 869static const char read_tree_usage[] = "git-read-tree (<sha> | [[-m [--aggressive] | --reset | --prefix=<prefix>] [-u | -i]] <sha1> [<sha2> [<sha3>]])";
 870
 871static struct lock_file lock_file;
 872
 873int cmd_read_tree(int argc, const char **argv, char **envp)
 874{
 875        int i, newfd, stage = 0;
 876        unsigned char sha1[20];
 877        merge_fn_t fn = NULL;
 878
 879        df_conflict_list.next = &df_conflict_list;
 880        state.base_dir = "";
 881        state.force = 1;
 882        state.quiet = 1;
 883        state.refresh_cache = 1;
 884
 885        setup_git_directory();
 886        git_config(git_default_config);
 887
 888        newfd = hold_lock_file_for_update(&lock_file, get_index_file());
 889        if (newfd < 0)
 890                die("unable to create new index file");
 891
 892        git_config(git_default_config);
 893
 894        merge = 0;
 895        reset = 0;
 896        for (i = 1; i < argc; i++) {
 897                const char *arg = argv[i];
 898
 899                /* "-u" means "update", meaning that a merge will update
 900                 * the working tree.
 901                 */
 902                if (!strcmp(arg, "-u")) {
 903                        update = 1;
 904                        continue;
 905                }
 906
 907                if (!strcmp(arg, "-v")) {
 908                        verbose_update = 1;
 909                        continue;
 910                }
 911
 912                /* "-i" means "index only", meaning that a merge will
 913                 * not even look at the working tree.
 914                 */
 915                if (!strcmp(arg, "-i")) {
 916                        index_only = 1;
 917                        continue;
 918                }
 919
 920                /* "--prefix=<subdirectory>/" means keep the current index
 921                 *  entries and put the entries from the tree under the
 922                 * given subdirectory.
 923                 */
 924                if (!strncmp(arg, "--prefix=", 9)) {
 925                        if (stage || merge || prefix)
 926                                usage(read_tree_usage);
 927                        prefix = arg + 9;
 928                        merge = 1;
 929                        stage = 1;
 930                        if (read_cache_unmerged())
 931                                die("you need to resolve your current index first");
 932                        continue;
 933                }
 934
 935                /* This differs from "-m" in that we'll silently ignore
 936                 * unmerged entries and overwrite working tree files that
 937                 * correspond to them.
 938                 */
 939                if (!strcmp(arg, "--reset")) {
 940                        if (stage || merge || prefix)
 941                                usage(read_tree_usage);
 942                        reset = 1;
 943                        merge = 1;
 944                        stage = 1;
 945                        read_cache_unmerged();
 946                        continue;
 947                }
 948
 949                if (!strcmp(arg, "--trivial")) {
 950                        trivial_merges_only = 1;
 951                        continue;
 952                }
 953
 954                if (!strcmp(arg, "--aggressive")) {
 955                        aggressive = 1;
 956                        continue;
 957                }
 958
 959                /* "-m" stands for "merge", meaning we start in stage 1 */
 960                if (!strcmp(arg, "-m")) {
 961                        if (stage || merge || prefix)
 962                                usage(read_tree_usage);
 963                        if (read_cache_unmerged())
 964                                die("you need to resolve your current index first");
 965                        stage = 1;
 966                        merge = 1;
 967                        continue;
 968                }
 969
 970                /* using -u and -i at the same time makes no sense */
 971                if (1 < index_only + update)
 972                        usage(read_tree_usage);
 973
 974                if (get_sha1(arg, sha1))
 975                        die("Not a valid object name %s", arg);
 976                if (list_tree(sha1) < 0)
 977                        die("failed to unpack tree object %s", arg);
 978                stage++;
 979        }
 980        if ((update||index_only) && !merge)
 981                usage(read_tree_usage);
 982
 983        if (prefix) {
 984                int pfxlen = strlen(prefix);
 985                int pos;
 986                if (prefix[pfxlen-1] != '/')
 987                        die("prefix must end with /");
 988                if (stage != 2)
 989                        die("binding merge takes only one tree");
 990                pos = cache_name_pos(prefix, pfxlen);
 991                if (0 <= pos)
 992                        die("corrupt index file");
 993                pos = -pos-1;
 994                if (pos < active_nr &&
 995                    !strncmp(active_cache[pos]->name, prefix, pfxlen))
 996                        die("subdirectory '%s' already exists.", prefix);
 997                pos = cache_name_pos(prefix, pfxlen-1);
 998                if (0 <= pos)
 999                        die("file '%.*s' already exists.", pfxlen-1, prefix);
1000        }
1001
1002        if (merge) {
1003                if (stage < 2)
1004                        die("just how do you expect me to merge %d trees?", stage-1);
1005                switch (stage - 1) {
1006                case 1:
1007                        fn = prefix ? bind_merge : oneway_merge;
1008                        break;
1009                case 2:
1010                        fn = twoway_merge;
1011                        break;
1012                case 3:
1013                default:
1014                        fn = threeway_merge;
1015                        cache_tree_free(&active_cache_tree);
1016                        break;
1017                }
1018
1019                if (stage - 1 >= 3)
1020                        head_idx = stage - 2;
1021                else
1022                        head_idx = 1;
1023        }
1024
1025        unpack_trees(fn);
1026
1027        /*
1028         * When reading only one tree (either the most basic form,
1029         * "-m ent" or "--reset ent" form), we can obtain a fully
1030         * valid cache-tree because the index must match exactly
1031         * what came from the tree.
1032         */
1033        if (trees && trees->item && !prefix && (!merge || (stage == 2))) {
1034                cache_tree_free(&active_cache_tree);
1035                prime_cache_tree();
1036        }
1037
1038        if (write_cache(newfd, active_cache, active_nr) ||
1039            close(newfd) || commit_lock_file(&lock_file))
1040                die("unable to write new index file");
1041        return 0;
1042}