Andrew's git / gitweb.git / read-tree.c
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read-tree.con commit Fix git-rev-list "date order" with --topo-order (2ed0288)
   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
  13static int merge = 0;
  14static int update = 0;
  15static int index_only = 0;
  16static int nontrivial_merge = 0;
  17static int trivial_merges_only = 0;
  18
  19static int head_idx = -1;
  20static int merge_size = 0;
  21
  22static struct object_list *trees = NULL;
  23
  24static struct cache_entry df_conflict_entry = { 
  25};
  26
  27static struct tree_entry_list df_conflict_list = {
  28        .name = NULL,
  29        .next = &df_conflict_list
  30};
  31
  32typedef int (*merge_fn_t)(struct cache_entry **src);
  33
  34static int entcmp(char *name1, int dir1, char *name2, int dir2)
  35{
  36        int len1 = strlen(name1);
  37        int len2 = strlen(name2);
  38        int len = len1 < len2 ? len1 : len2;
  39        int ret = memcmp(name1, name2, len);
  40        unsigned char c1, c2;
  41        if (ret)
  42                return ret;
  43        c1 = name1[len];
  44        c2 = name2[len];
  45        if (!c1 && dir1)
  46                c1 = '/';
  47        if (!c2 && dir2)
  48                c2 = '/';
  49        ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
  50        if (c1 && c2 && !ret)
  51                ret = len1 - len2;
  52        return ret;
  53}
  54
  55static int unpack_trees_rec(struct tree_entry_list **posns, int len,
  56                            const char *base, merge_fn_t fn, int *indpos)
  57{
  58        int baselen = strlen(base);
  59        int src_size = len + 1;
  60        do {
  61                int i;
  62                char *first;
  63                int firstdir = 0;
  64                int pathlen;
  65                unsigned ce_size;
  66                struct tree_entry_list **subposns;
  67                struct cache_entry **src;
  68                int any_files = 0;
  69                int any_dirs = 0;
  70                char *cache_name;
  71                int ce_stage;
  72
  73                /* Find the first name in the input. */
  74
  75                first = NULL;
  76                cache_name = NULL;
  77
  78                /* Check the cache */
  79                if (merge && *indpos < active_nr) {
  80                        /* This is a bit tricky: */
  81                        /* If the index has a subdirectory (with
  82                         * contents) as the first name, it'll get a
  83                         * filename like "foo/bar". But that's after
  84                         * "foo", so the entry in trees will get
  85                         * handled first, at which point we'll go into
  86                         * "foo", and deal with "bar" from the index,
  87                         * because the base will be "foo/". The only
  88                         * way we can actually have "foo/bar" first of
  89                         * all the things is if the trees don't
  90                         * contain "foo" at all, in which case we'll
  91                         * handle "foo/bar" without going into the
  92                         * directory, but that's fine (and will return
  93                         * an error anyway, with the added unknown
  94                         * file case.
  95                         */
  96
  97                        cache_name = active_cache[*indpos]->name;
  98                        if (strlen(cache_name) > baselen &&
  99                            !memcmp(cache_name, base, baselen)) {
 100                                cache_name += baselen;
 101                                first = cache_name;
 102                        } else {
 103                                cache_name = NULL;
 104                        }
 105                }
 106
 107#if DBRT_DEBUG > 1
 108                if (first)
 109                        printf("index %s\n", first);
 110#endif
 111                for (i = 0; i < len; i++) {
 112                        if (!posns[i] || posns[i] == &df_conflict_list)
 113                                continue;
 114#if DBRT_DEBUG > 1
 115                        printf("%d %s\n", i + 1, posns[i]->name);
 116#endif
 117                        if (!first || entcmp(first, firstdir,
 118                                             posns[i]->name, 
 119                                             posns[i]->directory) > 0) {
 120                                first = posns[i]->name;
 121                                firstdir = posns[i]->directory;
 122                        }
 123                }
 124                /* No name means we're done */
 125                if (!first)
 126                        return 0;
 127
 128                pathlen = strlen(first);
 129                ce_size = cache_entry_size(baselen + pathlen);
 130
 131                src = xmalloc(sizeof(struct cache_entry *) * src_size);
 132                memset(src, 0, sizeof(struct cache_entry *) * src_size);
 133
 134                subposns = xmalloc(sizeof(struct tree_list_entry *) * len);
 135                memset(subposns, 0, sizeof(struct tree_list_entry *) * len);
 136
 137                if (cache_name && !strcmp(cache_name, first)) {
 138                        any_files = 1;
 139                        src[0] = active_cache[*indpos];
 140                        remove_cache_entry_at(*indpos);
 141                }
 142
 143                for (i = 0; i < len; i++) {
 144                        struct cache_entry *ce;
 145
 146                        if (!posns[i] ||
 147                            (posns[i] != &df_conflict_list &&
 148                             strcmp(first, posns[i]->name))) {
 149                                continue;
 150                        }
 151
 152                        if (posns[i] == &df_conflict_list) {
 153                                src[i + merge] = &df_conflict_entry;
 154                                continue;
 155                        }
 156
 157                        if (posns[i]->directory) {
 158                                any_dirs = 1;
 159                                parse_tree(posns[i]->item.tree);
 160                                subposns[i] = posns[i]->item.tree->entries;
 161                                posns[i] = posns[i]->next;
 162                                src[i + merge] = &df_conflict_entry;
 163                                continue;
 164                        }
 165
 166                        if (!merge)
 167                                ce_stage = 0;
 168                        else if (i + 1 < head_idx)
 169                                ce_stage = 1;
 170                        else if (i + 1 > head_idx)
 171                                ce_stage = 3;
 172                        else
 173                                ce_stage = 2;
 174
 175                        ce = xmalloc(ce_size);
 176                        memset(ce, 0, ce_size);
 177                        ce->ce_mode = create_ce_mode(posns[i]->mode);
 178                        ce->ce_flags = create_ce_flags(baselen + pathlen,
 179                                                       ce_stage);
 180                        memcpy(ce->name, base, baselen);
 181                        memcpy(ce->name + baselen, first, pathlen + 1);
 182
 183                        any_files = 1;
 184
 185                        memcpy(ce->sha1, posns[i]->item.any->sha1, 20);
 186                        src[i + merge] = ce;
 187                        subposns[i] = &df_conflict_list;
 188                        posns[i] = posns[i]->next;
 189                }
 190                if (any_files) {
 191                        if (merge) {
 192                                int ret;
 193
 194#if DBRT_DEBUG > 1
 195                                printf("%s:\n", first);
 196                                for (i = 0; i < src_size; i++) {
 197                                        printf(" %d ", i);
 198                                        if (src[i])
 199                                                printf("%s\n", sha1_to_hex(src[i]->sha1));
 200                                        else
 201                                                printf("\n");
 202                                }
 203#endif
 204                                ret = fn(src);
 205                                
 206#if DBRT_DEBUG > 1
 207                                printf("Added %d entries\n", ret);
 208#endif
 209                                *indpos += ret;
 210                        } else {
 211                                for (i = 0; i < src_size; i++) {
 212                                        if (src[i]) {
 213                                                add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
 214                                        }
 215                                }
 216                        }
 217                }
 218                if (any_dirs) {
 219                        char *newbase = xmalloc(baselen + 2 + pathlen);
 220                        memcpy(newbase, base, baselen);
 221                        memcpy(newbase + baselen, first, pathlen);
 222                        newbase[baselen + pathlen] = '/';
 223                        newbase[baselen + pathlen + 1] = '\0';
 224                        if (unpack_trees_rec(subposns, len, newbase, fn,
 225                                             indpos))
 226                                return -1;
 227                        free(newbase);
 228                }
 229                free(subposns);
 230                free(src);
 231        } while (1);
 232}
 233
 234static void reject_merge(struct cache_entry *ce)
 235{
 236        die("Entry '%s' would be overwritten by merge. Cannot merge.", 
 237            ce->name);
 238}
 239
 240/* Unlink the last component and attempt to remove leading
 241 * directories, in case this unlink is the removal of the
 242 * last entry in the directory -- empty directories are removed.
 243 */
 244static void unlink_entry(char *name)
 245{
 246        char *cp, *prev;
 247
 248        if (unlink(name))
 249                return;
 250        prev = NULL;
 251        while (1) {
 252                int status;
 253                cp = strrchr(name, '/');
 254                if (prev)
 255                        *prev = '/';
 256                if (!cp)
 257                        break;
 258
 259                *cp = 0;
 260                status = rmdir(name);
 261                if (status) {
 262                        *cp = '/';
 263                        break;
 264                }
 265                prev = cp;
 266        }
 267}
 268
 269static void check_updates(struct cache_entry **src, int nr)
 270{
 271        static struct checkout state = {
 272                .base_dir = "",
 273                .force = 1,
 274                .quiet = 1,
 275                .refresh_cache = 1,
 276        };
 277        unsigned short mask = htons(CE_UPDATE);
 278        while (nr--) {
 279                struct cache_entry *ce = *src++;
 280                if (!ce->ce_mode) {
 281                        if (update)
 282                                unlink_entry(ce->name);
 283                        continue;
 284                }
 285                if (ce->ce_flags & mask) {
 286                        ce->ce_flags &= ~mask;
 287                        if (update)
 288                                checkout_entry(ce, &state);
 289                }
 290        }
 291}
 292
 293static int unpack_trees(merge_fn_t fn)
 294{
 295        int indpos = 0;
 296        unsigned len = object_list_length(trees);
 297        struct tree_entry_list **posns = 
 298                xmalloc(len * sizeof(struct tree_entry_list *));
 299        int i;
 300        struct object_list *posn = trees;
 301        merge_size = len;
 302        for (i = 0; i < len; i++) {
 303                posns[i] = ((struct tree *) posn->item)->entries;
 304                posn = posn->next;
 305        }
 306        if (unpack_trees_rec(posns, len, "", fn, &indpos))
 307                return -1;
 308
 309        if (trivial_merges_only && nontrivial_merge)
 310                die("Merge requires file-level merging");
 311
 312        check_updates(active_cache, active_nr);
 313        return 0;
 314}
 315
 316static int list_tree(unsigned char *sha1)
 317{
 318        struct tree *tree = parse_tree_indirect(sha1);
 319        if (!tree)
 320                return -1;
 321        object_list_append(&tree->object, &trees);
 322        return 0;
 323}
 324
 325static int same(struct cache_entry *a, struct cache_entry *b)
 326{
 327        if (!!a != !!b)
 328                return 0;
 329        if (!a && !b)
 330                return 1;
 331        return a->ce_mode == b->ce_mode && 
 332                !memcmp(a->sha1, b->sha1, 20);
 333}
 334
 335
 336/*
 337 * When a CE gets turned into an unmerged entry, we
 338 * want it to be up-to-date
 339 */
 340static void verify_uptodate(struct cache_entry *ce)
 341{
 342        struct stat st;
 343
 344        if (index_only)
 345                return;
 346
 347        if (!lstat(ce->name, &st)) {
 348                unsigned changed = ce_match_stat(ce, &st);
 349                if (!changed)
 350                        return;
 351                errno = 0;
 352        }
 353        if (errno == ENOENT)
 354                return;
 355        die("Entry '%s' not uptodate. Cannot merge.", ce->name);
 356}
 357
 358static int merged_entry(struct cache_entry *merge, struct cache_entry *old)
 359{
 360        merge->ce_flags |= htons(CE_UPDATE);
 361        if (old) {
 362                /*
 363                 * See if we can re-use the old CE directly?
 364                 * That way we get the uptodate stat info.
 365                 *
 366                 * This also removes the UPDATE flag on
 367                 * a match.
 368                 */
 369                if (same(old, merge)) {
 370                        *merge = *old;
 371                } else {
 372                        verify_uptodate(old);
 373                }
 374        }
 375        merge->ce_flags &= ~htons(CE_STAGEMASK);
 376        add_cache_entry(merge, ADD_CACHE_OK_TO_ADD);
 377        return 1;
 378}
 379
 380static int deleted_entry(struct cache_entry *ce, struct cache_entry *old)
 381{
 382        if (old)
 383                verify_uptodate(old);
 384        ce->ce_mode = 0;
 385        add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
 386        return 1;
 387}
 388
 389static int keep_entry(struct cache_entry *ce)
 390{
 391        add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
 392        return 1;
 393}
 394
 395#if DBRT_DEBUG
 396static void show_stage_entry(FILE *o,
 397                             const char *label, const struct cache_entry *ce)
 398{
 399        if (!ce)
 400                fprintf(o, "%s (missing)\n", label);
 401        else
 402                fprintf(o, "%s%06o %s %d\t%s\n",
 403                        label,
 404                        ntohl(ce->ce_mode),
 405                        sha1_to_hex(ce->sha1),
 406                        ce_stage(ce),
 407                        ce->name);
 408}
 409#endif
 410
 411static int threeway_merge(struct cache_entry **stages)
 412{
 413        struct cache_entry *index;
 414        struct cache_entry *head; 
 415        struct cache_entry *remote = stages[head_idx + 1];
 416        int count;
 417        int head_match = 0;
 418        int remote_match = 0;
 419
 420        int df_conflict_head = 0;
 421        int df_conflict_remote = 0;
 422
 423        int any_anc_missing = 0;
 424        int i;
 425
 426        for (i = 1; i < head_idx; i++) {
 427                if (!stages[i])
 428                        any_anc_missing = 1;
 429        }
 430
 431        index = stages[0];
 432        head = stages[head_idx];
 433
 434        if (head == &df_conflict_entry) {
 435                df_conflict_head = 1;
 436                head = NULL;
 437        }
 438
 439        if (remote == &df_conflict_entry) {
 440                df_conflict_remote = 1;
 441                remote = NULL;
 442        }
 443
 444        /* First, if there's a #16 situation, note that to prevent #13
 445         * and #14. 
 446         */
 447        if (!same(remote, head)) {
 448                for (i = 1; i < head_idx; i++) {
 449                        if (same(stages[i], head)) {
 450                                head_match = i;
 451                        }
 452                        if (same(stages[i], remote)) {
 453                                remote_match = i;
 454                        }
 455                }
 456        }
 457
 458        /* We start with cases where the index is allowed to match
 459         * something other than the head: #14(ALT) and #2ALT, where it
 460         * is permitted to match the result instead.
 461         */
 462        /* #14, #14ALT, #2ALT */
 463        if (remote && !df_conflict_head && head_match && !remote_match) {
 464                if (index && !same(index, remote) && !same(index, head))
 465                        reject_merge(index);
 466                return merged_entry(remote, index);
 467        }
 468        /*
 469         * If we have an entry in the index cache, then we want to
 470         * make sure that it matches head.
 471         */
 472        if (index && !same(index, head)) {
 473                reject_merge(index);
 474        }
 475
 476        if (head) {
 477                /* #5ALT, #15 */
 478                if (same(head, remote))
 479                        return merged_entry(head, index);
 480                /* #13, #3ALT */
 481                if (!df_conflict_remote && remote_match && !head_match)
 482                        return merged_entry(head, index);
 483        }
 484
 485        /* #1 */
 486        if (!head && !remote && any_anc_missing)
 487                return 0;
 488
 489        /* Below are "no merge" cases, which require that the index be
 490         * up-to-date to avoid the files getting overwritten with
 491         * conflict resolution files. 
 492         */
 493        if (index) {
 494                verify_uptodate(index);
 495        }
 496
 497        nontrivial_merge = 1;
 498
 499        /* #2, #3, #4, #6, #7, #9, #11. */
 500        count = 0;
 501        if (!head_match || !remote_match) {
 502                for (i = 1; i < head_idx; i++) {
 503                        if (stages[i]) {
 504                                keep_entry(stages[i]);
 505                                count++;
 506                                break;
 507                        }
 508                }
 509        }
 510#if DBRT_DEBUG
 511        else {
 512                fprintf(stderr, "read-tree: warning #16 detected\n");
 513                show_stage_entry(stderr, "head   ", stages[head_match]);
 514                show_stage_entry(stderr, "remote ", stages[remote_match]);
 515        }
 516#endif
 517        if (head) { count += keep_entry(head); }
 518        if (remote) { count += keep_entry(remote); }
 519        return count;
 520}
 521
 522/*
 523 * Two-way merge.
 524 *
 525 * The rule is to "carry forward" what is in the index without losing
 526 * information across a "fast forward", favoring a successful merge
 527 * over a merge failure when it makes sense.  For details of the
 528 * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
 529 *
 530 */
 531static int twoway_merge(struct cache_entry **src)
 532{
 533        struct cache_entry *current = src[0];
 534        struct cache_entry *oldtree = src[1], *newtree = src[2];
 535
 536        if (merge_size != 2)
 537                return error("Cannot do a twoway merge of %d trees\n",
 538                             merge_size);
 539
 540        if (current) {
 541                if ((!oldtree && !newtree) || /* 4 and 5 */
 542                    (!oldtree && newtree &&
 543                     same(current, newtree)) || /* 6 and 7 */
 544                    (oldtree && newtree &&
 545                     same(oldtree, newtree)) || /* 14 and 15 */
 546                    (oldtree && newtree &&
 547                     !same(oldtree, newtree) && /* 18 and 19*/
 548                     same(current, newtree))) {
 549                        return keep_entry(current);
 550                }
 551                else if (oldtree && !newtree && same(current, oldtree)) {
 552                        /* 10 or 11 */
 553                        return deleted_entry(oldtree, current);
 554                }
 555                else if (oldtree && newtree &&
 556                         same(current, oldtree) && !same(current, newtree)) {
 557                        /* 20 or 21 */
 558                        return merged_entry(newtree, current);
 559                }
 560                else {
 561                        /* all other failures */
 562                        if (oldtree)
 563                                reject_merge(oldtree);
 564                        if (current)
 565                                reject_merge(current);
 566                        if (newtree)
 567                                reject_merge(newtree);
 568                        return -1;
 569                }
 570        }
 571        else if (newtree)
 572                return merged_entry(newtree, current);
 573        else
 574                return deleted_entry(oldtree, current);
 575}
 576
 577/*
 578 * One-way merge.
 579 *
 580 * The rule is:
 581 * - take the stat information from stage0, take the data from stage1
 582 */
 583static int oneway_merge(struct cache_entry **src)
 584{
 585        struct cache_entry *old = src[0];
 586        struct cache_entry *a = src[1];
 587
 588        if (merge_size != 1)
 589                return error("Cannot do a oneway merge of %d trees\n",
 590                             merge_size);
 591
 592        if (!a)
 593                return 0;
 594        if (old && same(old, a)) {
 595                return keep_entry(old);
 596        }
 597        return merged_entry(a, NULL);
 598}
 599
 600static int read_cache_unmerged(void)
 601{
 602        int i, deleted;
 603        struct cache_entry **dst;
 604
 605        read_cache();
 606        dst = active_cache;
 607        deleted = 0;
 608        for (i = 0; i < active_nr; i++) {
 609                struct cache_entry *ce = active_cache[i];
 610                if (ce_stage(ce)) {
 611                        deleted++;
 612                        continue;
 613                }
 614                if (deleted)
 615                        *dst = ce;
 616                dst++;
 617        }
 618        active_nr -= deleted;
 619        return deleted;
 620}
 621
 622static const char read_tree_usage[] = "git-read-tree (<sha> | -m [-u | -i] <sha1> [<sha2> [<sha3>]])";
 623
 624static struct cache_file cache_file;
 625
 626int main(int argc, char **argv)
 627{
 628        int i, newfd, reset, stage = 0;
 629        unsigned char sha1[20];
 630        merge_fn_t fn = NULL;
 631
 632        newfd = hold_index_file_for_update(&cache_file, get_index_file());
 633        if (newfd < 0)
 634                die("unable to create new cachefile");
 635
 636        git_config(git_default_config);
 637
 638        merge = 0;
 639        reset = 0;
 640        for (i = 1; i < argc; i++) {
 641                const char *arg = argv[i];
 642
 643                /* "-u" means "update", meaning that a merge will update
 644                 * the working tree.
 645                 */
 646                if (!strcmp(arg, "-u")) {
 647                        update = 1;
 648                        continue;
 649                }
 650
 651                /* "-i" means "index only", meaning that a merge will
 652                 * not even look at the working tree.
 653                 */
 654                if (!strcmp(arg, "-i")) {
 655                        index_only = 1;
 656                        continue;
 657                }
 658
 659                /* This differs from "-m" in that we'll silently ignore unmerged entries */
 660                if (!strcmp(arg, "--reset")) {
 661                        if (stage || merge)
 662                                usage(read_tree_usage);
 663                        reset = 1;
 664                        merge = 1;
 665                        stage = 1;
 666                        read_cache_unmerged();
 667                        continue;
 668                }
 669
 670                if (!strcmp(arg, "--trivial")) {
 671                        trivial_merges_only = 1;
 672                        continue;
 673                }
 674
 675                /* "-m" stands for "merge", meaning we start in stage 1 */
 676                if (!strcmp(arg, "-m")) {
 677                        if (stage || merge)
 678                                usage(read_tree_usage);
 679                        if (read_cache_unmerged())
 680                                die("you need to resolve your current index first");
 681                        stage = 1;
 682                        merge = 1;
 683                        continue;
 684                }
 685
 686                /* using -u and -i at the same time makes no sense */
 687                if (1 < index_only + update)
 688                        usage(read_tree_usage);
 689
 690                if (get_sha1(arg, sha1) < 0)
 691                        usage(read_tree_usage);
 692                if (list_tree(sha1) < 0)
 693                        die("failed to unpack tree object %s", arg);
 694                stage++;
 695        }
 696        if ((update||index_only) && !merge)
 697                usage(read_tree_usage);
 698
 699        if (merge) {
 700                if (stage < 2)
 701                        die("just how do you expect me to merge %d trees?", stage-1);
 702                switch (stage - 1) {
 703                case 1:
 704                        fn = oneway_merge;
 705                        break;
 706                case 2:
 707                        fn = twoway_merge;
 708                        break;
 709                case 3:
 710                        fn = threeway_merge;
 711                        break;
 712                default:
 713                        fn = threeway_merge;
 714                        break;
 715                }
 716
 717                if (stage - 1 >= 3)
 718                        head_idx = stage - 2;
 719                else
 720                        head_idx = 1;
 721        }
 722
 723        unpack_trees(fn);
 724        if (write_cache(newfd, active_cache, active_nr) ||
 725            commit_index_file(&cache_file))
 726                die("unable to write new index file");
 727        return 0;
 728}