notes-merge.con commit Merge branch 'nd/fetch-ref-summary' (566fdaf)
   1#include "cache.h"
   2#include "commit.h"
   3#include "refs.h"
   4#include "diff.h"
   5#include "diffcore.h"
   6#include "xdiff-interface.h"
   7#include "ll-merge.h"
   8#include "dir.h"
   9#include "notes.h"
  10#include "notes-merge.h"
  11#include "strbuf.h"
  12#include "notes-utils.h"
  13
  14struct notes_merge_pair {
  15        unsigned char obj[20], base[20], local[20], remote[20];
  16};
  17
  18void init_notes_merge_options(struct notes_merge_options *o)
  19{
  20        memset(o, 0, sizeof(struct notes_merge_options));
  21        strbuf_init(&(o->commit_msg), 0);
  22        o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
  23}
  24
  25static int path_to_sha1(const char *path, unsigned char *sha1)
  26{
  27        char hex_sha1[40];
  28        int i = 0;
  29        while (*path && i < 40) {
  30                if (*path != '/')
  31                        hex_sha1[i++] = *path;
  32                path++;
  33        }
  34        if (*path || i != 40)
  35                return -1;
  36        return get_sha1_hex(hex_sha1, sha1);
  37}
  38
  39static int verify_notes_filepair(struct diff_filepair *p, unsigned char *sha1)
  40{
  41        switch (p->status) {
  42        case DIFF_STATUS_MODIFIED:
  43                assert(p->one->mode == p->two->mode);
  44                assert(!is_null_oid(&p->one->oid));
  45                assert(!is_null_oid(&p->two->oid));
  46                break;
  47        case DIFF_STATUS_ADDED:
  48                assert(is_null_oid(&p->one->oid));
  49                break;
  50        case DIFF_STATUS_DELETED:
  51                assert(is_null_oid(&p->two->oid));
  52                break;
  53        default:
  54                return -1;
  55        }
  56        assert(!strcmp(p->one->path, p->two->path));
  57        return path_to_sha1(p->one->path, sha1);
  58}
  59
  60static struct notes_merge_pair *find_notes_merge_pair_pos(
  61                struct notes_merge_pair *list, int len, unsigned char *obj,
  62                int insert_new, int *occupied)
  63{
  64        /*
  65         * Both diff_tree_remote() and diff_tree_local() tend to process
  66         * merge_pairs in ascending order. Therefore, cache last returned
  67         * index, and search sequentially from there until the appropriate
  68         * position is found.
  69         *
  70         * Since inserts only happen from diff_tree_remote() (which mainly
  71         * _appends_), we don't care that inserting into the middle of the
  72         * list is expensive (using memmove()).
  73         */
  74        static int last_index;
  75        int i = last_index < len ? last_index : len - 1;
  76        int prev_cmp = 0, cmp = -1;
  77        while (i >= 0 && i < len) {
  78                cmp = hashcmp(obj, list[i].obj);
  79                if (!cmp) /* obj belongs @ i */
  80                        break;
  81                else if (cmp < 0 && prev_cmp <= 0) /* obj belongs < i */
  82                        i--;
  83                else if (cmp < 0) /* obj belongs between i-1 and i */
  84                        break;
  85                else if (cmp > 0 && prev_cmp >= 0) /* obj belongs > i */
  86                        i++;
  87                else /* if (cmp > 0) */ { /* obj belongs between i and i+1 */
  88                        i++;
  89                        break;
  90                }
  91                prev_cmp = cmp;
  92        }
  93        if (i < 0)
  94                i = 0;
  95        /* obj belongs at, or immediately preceding, index i (0 <= i <= len) */
  96
  97        if (!cmp)
  98                *occupied = 1;
  99        else {
 100                *occupied = 0;
 101                if (insert_new && i < len) {
 102                        memmove(list + i + 1, list + i,
 103                                (len - i) * sizeof(struct notes_merge_pair));
 104                        memset(list + i, 0, sizeof(struct notes_merge_pair));
 105                }
 106        }
 107        last_index = i;
 108        return list + i;
 109}
 110
 111static unsigned char uninitialized[20] =
 112        "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" \
 113        "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff";
 114
 115static struct notes_merge_pair *diff_tree_remote(struct notes_merge_options *o,
 116                                                 const unsigned char *base,
 117                                                 const unsigned char *remote,
 118                                                 int *num_changes)
 119{
 120        struct diff_options opt;
 121        struct notes_merge_pair *changes;
 122        int i, len = 0;
 123
 124        trace_printf("\tdiff_tree_remote(base = %.7s, remote = %.7s)\n",
 125               sha1_to_hex(base), sha1_to_hex(remote));
 126
 127        diff_setup(&opt);
 128        DIFF_OPT_SET(&opt, RECURSIVE);
 129        opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 130        diff_setup_done(&opt);
 131        diff_tree_sha1(base, remote, "", &opt);
 132        diffcore_std(&opt);
 133
 134        changes = xcalloc(diff_queued_diff.nr, sizeof(struct notes_merge_pair));
 135
 136        for (i = 0; i < diff_queued_diff.nr; i++) {
 137                struct diff_filepair *p = diff_queued_diff.queue[i];
 138                struct notes_merge_pair *mp;
 139                int occupied;
 140                unsigned char obj[20];
 141
 142                if (verify_notes_filepair(p, obj)) {
 143                        trace_printf("\t\tCannot merge entry '%s' (%c): "
 144                               "%.7s -> %.7s. Skipping!\n", p->one->path,
 145                               p->status, oid_to_hex(&p->one->oid),
 146                               oid_to_hex(&p->two->oid));
 147                        continue;
 148                }
 149                mp = find_notes_merge_pair_pos(changes, len, obj, 1, &occupied);
 150                if (occupied) {
 151                        /* We've found an addition/deletion pair */
 152                        assert(!hashcmp(mp->obj, obj));
 153                        if (is_null_oid(&p->one->oid)) { /* addition */
 154                                assert(is_null_sha1(mp->remote));
 155                                hashcpy(mp->remote, p->two->oid.hash);
 156                        } else if (is_null_oid(&p->two->oid)) { /* deletion */
 157                                assert(is_null_sha1(mp->base));
 158                                hashcpy(mp->base, p->one->oid.hash);
 159                        } else
 160                                assert(!"Invalid existing change recorded");
 161                } else {
 162                        hashcpy(mp->obj, obj);
 163                        hashcpy(mp->base, p->one->oid.hash);
 164                        hashcpy(mp->local, uninitialized);
 165                        hashcpy(mp->remote, p->two->oid.hash);
 166                        len++;
 167                }
 168                trace_printf("\t\tStored remote change for %s: %.7s -> %.7s\n",
 169                       sha1_to_hex(mp->obj), sha1_to_hex(mp->base),
 170                       sha1_to_hex(mp->remote));
 171        }
 172        diff_flush(&opt);
 173        clear_pathspec(&opt.pathspec);
 174
 175        *num_changes = len;
 176        return changes;
 177}
 178
 179static void diff_tree_local(struct notes_merge_options *o,
 180                            struct notes_merge_pair *changes, int len,
 181                            const unsigned char *base,
 182                            const unsigned char *local)
 183{
 184        struct diff_options opt;
 185        int i;
 186
 187        trace_printf("\tdiff_tree_local(len = %i, base = %.7s, local = %.7s)\n",
 188               len, sha1_to_hex(base), sha1_to_hex(local));
 189
 190        diff_setup(&opt);
 191        DIFF_OPT_SET(&opt, RECURSIVE);
 192        opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 193        diff_setup_done(&opt);
 194        diff_tree_sha1(base, local, "", &opt);
 195        diffcore_std(&opt);
 196
 197        for (i = 0; i < diff_queued_diff.nr; i++) {
 198                struct diff_filepair *p = diff_queued_diff.queue[i];
 199                struct notes_merge_pair *mp;
 200                int match;
 201                unsigned char obj[20];
 202
 203                if (verify_notes_filepair(p, obj)) {
 204                        trace_printf("\t\tCannot merge entry '%s' (%c): "
 205                               "%.7s -> %.7s. Skipping!\n", p->one->path,
 206                               p->status, oid_to_hex(&p->one->oid),
 207                               oid_to_hex(&p->two->oid));
 208                        continue;
 209                }
 210                mp = find_notes_merge_pair_pos(changes, len, obj, 0, &match);
 211                if (!match) {
 212                        trace_printf("\t\tIgnoring local-only change for %s: "
 213                               "%.7s -> %.7s\n", sha1_to_hex(obj),
 214                               oid_to_hex(&p->one->oid),
 215                               oid_to_hex(&p->two->oid));
 216                        continue;
 217                }
 218
 219                assert(!hashcmp(mp->obj, obj));
 220                if (is_null_oid(&p->two->oid)) { /* deletion */
 221                        /*
 222                         * Either this is a true deletion (1), or it is part
 223                         * of an A/D pair (2), or D/A pair (3):
 224                         *
 225                         * (1) mp->local is uninitialized; set it to null_sha1
 226                         * (2) mp->local is not uninitialized; don't touch it
 227                         * (3) mp->local is uninitialized; set it to null_sha1
 228                         *     (will be overwritten by following addition)
 229                         */
 230                        if (!hashcmp(mp->local, uninitialized))
 231                                hashclr(mp->local);
 232                } else if (is_null_oid(&p->one->oid)) { /* addition */
 233                        /*
 234                         * Either this is a true addition (1), or it is part
 235                         * of an A/D pair (2), or D/A pair (3):
 236                         *
 237                         * (1) mp->local is uninitialized; set to p->two->sha1
 238                         * (2) mp->local is uninitialized; set to p->two->sha1
 239                         * (3) mp->local is null_sha1;     set to p->two->sha1
 240                         */
 241                        assert(is_null_sha1(mp->local) ||
 242                               !hashcmp(mp->local, uninitialized));
 243                        hashcpy(mp->local, p->two->oid.hash);
 244                } else { /* modification */
 245                        /*
 246                         * This is a true modification. p->one->sha1 shall
 247                         * match mp->base, and mp->local shall be uninitialized.
 248                         * Set mp->local to p->two->sha1.
 249                         */
 250                        assert(!hashcmp(p->one->oid.hash, mp->base));
 251                        assert(!hashcmp(mp->local, uninitialized));
 252                        hashcpy(mp->local, p->two->oid.hash);
 253                }
 254                trace_printf("\t\tStored local change for %s: %.7s -> %.7s\n",
 255                       sha1_to_hex(mp->obj), sha1_to_hex(mp->base),
 256                       sha1_to_hex(mp->local));
 257        }
 258        diff_flush(&opt);
 259        clear_pathspec(&opt.pathspec);
 260}
 261
 262static void check_notes_merge_worktree(struct notes_merge_options *o)
 263{
 264        if (!o->has_worktree) {
 265                /*
 266                 * Must establish NOTES_MERGE_WORKTREE.
 267                 * Abort if NOTES_MERGE_WORKTREE already exists
 268                 */
 269                if (file_exists(git_path(NOTES_MERGE_WORKTREE)) &&
 270                    !is_empty_dir(git_path(NOTES_MERGE_WORKTREE))) {
 271                        if (advice_resolve_conflict)
 272                                die("You have not concluded your previous "
 273                                    "notes merge (%s exists).\nPlease, use "
 274                                    "'git notes merge --commit' or 'git notes "
 275                                    "merge --abort' to commit/abort the "
 276                                    "previous merge before you start a new "
 277                                    "notes merge.", git_path("NOTES_MERGE_*"));
 278                        else
 279                                die("You have not concluded your notes merge "
 280                                    "(%s exists).", git_path("NOTES_MERGE_*"));
 281                }
 282
 283                if (safe_create_leading_directories_const(git_path(
 284                                NOTES_MERGE_WORKTREE "/.test")))
 285                        die_errno("unable to create directory %s",
 286                                  git_path(NOTES_MERGE_WORKTREE));
 287                o->has_worktree = 1;
 288        } else if (!file_exists(git_path(NOTES_MERGE_WORKTREE)))
 289                /* NOTES_MERGE_WORKTREE should already be established */
 290                die("missing '%s'. This should not happen",
 291                    git_path(NOTES_MERGE_WORKTREE));
 292}
 293
 294static void write_buf_to_worktree(const unsigned char *obj,
 295                                  const char *buf, unsigned long size)
 296{
 297        int fd;
 298        char *path = git_pathdup(NOTES_MERGE_WORKTREE "/%s", sha1_to_hex(obj));
 299        if (safe_create_leading_directories_const(path))
 300                die_errno("unable to create directory for '%s'", path);
 301        if (file_exists(path))
 302                die("found existing file at '%s'", path);
 303
 304        fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, 0666);
 305        if (fd < 0)
 306                die_errno("failed to open '%s'", path);
 307
 308        while (size > 0) {
 309                long ret = write_in_full(fd, buf, size);
 310                if (ret < 0) {
 311                        /* Ignore epipe */
 312                        if (errno == EPIPE)
 313                                break;
 314                        die_errno("notes-merge");
 315                } else if (!ret) {
 316                        die("notes-merge: disk full?");
 317                }
 318                size -= ret;
 319                buf += ret;
 320        }
 321
 322        close(fd);
 323        free(path);
 324}
 325
 326static void write_note_to_worktree(const unsigned char *obj,
 327                                   const unsigned char *note)
 328{
 329        enum object_type type;
 330        unsigned long size;
 331        void *buf = read_sha1_file(note, &type, &size);
 332
 333        if (!buf)
 334                die("cannot read note %s for object %s",
 335                    sha1_to_hex(note), sha1_to_hex(obj));
 336        if (type != OBJ_BLOB)
 337                die("blob expected in note %s for object %s",
 338                    sha1_to_hex(note), sha1_to_hex(obj));
 339        write_buf_to_worktree(obj, buf, size);
 340        free(buf);
 341}
 342
 343static int ll_merge_in_worktree(struct notes_merge_options *o,
 344                                struct notes_merge_pair *p)
 345{
 346        mmbuffer_t result_buf;
 347        mmfile_t base, local, remote;
 348        int status;
 349
 350        read_mmblob(&base, p->base);
 351        read_mmblob(&local, p->local);
 352        read_mmblob(&remote, p->remote);
 353
 354        status = ll_merge(&result_buf, sha1_to_hex(p->obj), &base, NULL,
 355                          &local, o->local_ref, &remote, o->remote_ref, NULL);
 356
 357        free(base.ptr);
 358        free(local.ptr);
 359        free(remote.ptr);
 360
 361        if ((status < 0) || !result_buf.ptr)
 362                die("Failed to execute internal merge");
 363
 364        write_buf_to_worktree(p->obj, result_buf.ptr, result_buf.size);
 365        free(result_buf.ptr);
 366
 367        return status;
 368}
 369
 370static int merge_one_change_manual(struct notes_merge_options *o,
 371                                   struct notes_merge_pair *p,
 372                                   struct notes_tree *t)
 373{
 374        const char *lref = o->local_ref ? o->local_ref : "local version";
 375        const char *rref = o->remote_ref ? o->remote_ref : "remote version";
 376
 377        trace_printf("\t\t\tmerge_one_change_manual(obj = %.7s, base = %.7s, "
 378               "local = %.7s, remote = %.7s)\n",
 379               sha1_to_hex(p->obj), sha1_to_hex(p->base),
 380               sha1_to_hex(p->local), sha1_to_hex(p->remote));
 381
 382        /* add "Conflicts:" section to commit message first time through */
 383        if (!o->has_worktree)
 384                strbuf_addstr(&(o->commit_msg), "\n\nConflicts:\n");
 385
 386        strbuf_addf(&(o->commit_msg), "\t%s\n", sha1_to_hex(p->obj));
 387
 388        if (o->verbosity >= 2)
 389                printf("Auto-merging notes for %s\n", sha1_to_hex(p->obj));
 390        check_notes_merge_worktree(o);
 391        if (is_null_sha1(p->local)) {
 392                /* D/F conflict, checkout p->remote */
 393                assert(!is_null_sha1(p->remote));
 394                if (o->verbosity >= 1)
 395                        printf("CONFLICT (delete/modify): Notes for object %s "
 396                                "deleted in %s and modified in %s. Version from %s "
 397                                "left in tree.\n",
 398                                sha1_to_hex(p->obj), lref, rref, rref);
 399                write_note_to_worktree(p->obj, p->remote);
 400        } else if (is_null_sha1(p->remote)) {
 401                /* D/F conflict, checkout p->local */
 402                assert(!is_null_sha1(p->local));
 403                if (o->verbosity >= 1)
 404                        printf("CONFLICT (delete/modify): Notes for object %s "
 405                                "deleted in %s and modified in %s. Version from %s "
 406                                "left in tree.\n",
 407                                sha1_to_hex(p->obj), rref, lref, lref);
 408                write_note_to_worktree(p->obj, p->local);
 409        } else {
 410                /* "regular" conflict, checkout result of ll_merge() */
 411                const char *reason = "content";
 412                if (is_null_sha1(p->base))
 413                        reason = "add/add";
 414                assert(!is_null_sha1(p->local));
 415                assert(!is_null_sha1(p->remote));
 416                if (o->verbosity >= 1)
 417                        printf("CONFLICT (%s): Merge conflict in notes for "
 418                                "object %s\n", reason, sha1_to_hex(p->obj));
 419                ll_merge_in_worktree(o, p);
 420        }
 421
 422        trace_printf("\t\t\tremoving from partial merge result\n");
 423        remove_note(t, p->obj);
 424
 425        return 1;
 426}
 427
 428static int merge_one_change(struct notes_merge_options *o,
 429                            struct notes_merge_pair *p, struct notes_tree *t)
 430{
 431        /*
 432         * Return 0 if change is successfully resolved (stored in notes_tree).
 433         * Return 1 is change results in a conflict (NOT stored in notes_tree,
 434         * but instead written to NOTES_MERGE_WORKTREE with conflict markers).
 435         */
 436        switch (o->strategy) {
 437        case NOTES_MERGE_RESOLVE_MANUAL:
 438                return merge_one_change_manual(o, p, t);
 439        case NOTES_MERGE_RESOLVE_OURS:
 440                if (o->verbosity >= 2)
 441                        printf("Using local notes for %s\n",
 442                                                sha1_to_hex(p->obj));
 443                /* nothing to do */
 444                return 0;
 445        case NOTES_MERGE_RESOLVE_THEIRS:
 446                if (o->verbosity >= 2)
 447                        printf("Using remote notes for %s\n",
 448                                                sha1_to_hex(p->obj));
 449                if (add_note(t, p->obj, p->remote, combine_notes_overwrite))
 450                        die("BUG: combine_notes_overwrite failed");
 451                return 0;
 452        case NOTES_MERGE_RESOLVE_UNION:
 453                if (o->verbosity >= 2)
 454                        printf("Concatenating local and remote notes for %s\n",
 455                                                        sha1_to_hex(p->obj));
 456                if (add_note(t, p->obj, p->remote, combine_notes_concatenate))
 457                        die("failed to concatenate notes "
 458                            "(combine_notes_concatenate)");
 459                return 0;
 460        case NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ:
 461                if (o->verbosity >= 2)
 462                        printf("Concatenating unique lines in local and remote "
 463                                "notes for %s\n", sha1_to_hex(p->obj));
 464                if (add_note(t, p->obj, p->remote, combine_notes_cat_sort_uniq))
 465                        die("failed to concatenate notes "
 466                            "(combine_notes_cat_sort_uniq)");
 467                return 0;
 468        }
 469        die("Unknown strategy (%i).", o->strategy);
 470}
 471
 472static int merge_changes(struct notes_merge_options *o,
 473                         struct notes_merge_pair *changes, int *num_changes,
 474                         struct notes_tree *t)
 475{
 476        int i, conflicts = 0;
 477
 478        trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
 479        for (i = 0; i < *num_changes; i++) {
 480                struct notes_merge_pair *p = changes + i;
 481                trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
 482                       sha1_to_hex(p->obj), sha1_to_hex(p->base),
 483                       sha1_to_hex(p->local), sha1_to_hex(p->remote));
 484
 485                if (!hashcmp(p->base, p->remote)) {
 486                        /* no remote change; nothing to do */
 487                        trace_printf("\t\t\tskipping (no remote change)\n");
 488                } else if (!hashcmp(p->local, p->remote)) {
 489                        /* same change in local and remote; nothing to do */
 490                        trace_printf("\t\t\tskipping (local == remote)\n");
 491                } else if (!hashcmp(p->local, uninitialized) ||
 492                           !hashcmp(p->local, p->base)) {
 493                        /* no local change; adopt remote change */
 494                        trace_printf("\t\t\tno local change, adopted remote\n");
 495                        if (add_note(t, p->obj, p->remote,
 496                                     combine_notes_overwrite))
 497                                die("BUG: combine_notes_overwrite failed");
 498                } else {
 499                        /* need file-level merge between local and remote */
 500                        trace_printf("\t\t\tneed content-level merge\n");
 501                        conflicts += merge_one_change(o, p, t);
 502                }
 503        }
 504
 505        return conflicts;
 506}
 507
 508static int merge_from_diffs(struct notes_merge_options *o,
 509                            const unsigned char *base,
 510                            const unsigned char *local,
 511                            const unsigned char *remote, struct notes_tree *t)
 512{
 513        struct notes_merge_pair *changes;
 514        int num_changes, conflicts;
 515
 516        trace_printf("\tmerge_from_diffs(base = %.7s, local = %.7s, "
 517               "remote = %.7s)\n", sha1_to_hex(base), sha1_to_hex(local),
 518               sha1_to_hex(remote));
 519
 520        changes = diff_tree_remote(o, base, remote, &num_changes);
 521        diff_tree_local(o, changes, num_changes, base, local);
 522
 523        conflicts = merge_changes(o, changes, &num_changes, t);
 524        free(changes);
 525
 526        if (o->verbosity >= 4)
 527                printf(t->dirty ?
 528                       "Merge result: %i unmerged notes and a dirty notes tree\n" :
 529                       "Merge result: %i unmerged notes and a clean notes tree\n",
 530                       conflicts);
 531
 532        return conflicts ? -1 : 1;
 533}
 534
 535int notes_merge(struct notes_merge_options *o,
 536                struct notes_tree *local_tree,
 537                unsigned char *result_sha1)
 538{
 539        unsigned char local_sha1[20], remote_sha1[20];
 540        struct commit *local, *remote;
 541        struct commit_list *bases = NULL;
 542        const unsigned char *base_sha1, *base_tree_sha1;
 543        int result = 0;
 544
 545        assert(o->local_ref && o->remote_ref);
 546        assert(!strcmp(o->local_ref, local_tree->ref));
 547        hashclr(result_sha1);
 548
 549        trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
 550               o->local_ref, o->remote_ref);
 551
 552        /* Dereference o->local_ref into local_sha1 */
 553        if (read_ref_full(o->local_ref, 0, local_sha1, NULL))
 554                die("Failed to resolve local notes ref '%s'", o->local_ref);
 555        else if (!check_refname_format(o->local_ref, 0) &&
 556                is_null_sha1(local_sha1))
 557                local = NULL; /* local_sha1 == null_sha1 indicates unborn ref */
 558        else if (!(local = lookup_commit_reference(local_sha1)))
 559                die("Could not parse local commit %s (%s)",
 560                    sha1_to_hex(local_sha1), o->local_ref);
 561        trace_printf("\tlocal commit: %.7s\n", sha1_to_hex(local_sha1));
 562
 563        /* Dereference o->remote_ref into remote_sha1 */
 564        if (get_sha1(o->remote_ref, remote_sha1)) {
 565                /*
 566                 * Failed to get remote_sha1. If o->remote_ref looks like an
 567                 * unborn ref, perform the merge using an empty notes tree.
 568                 */
 569                if (!check_refname_format(o->remote_ref, 0)) {
 570                        hashclr(remote_sha1);
 571                        remote = NULL;
 572                } else {
 573                        die("Failed to resolve remote notes ref '%s'",
 574                            o->remote_ref);
 575                }
 576        } else if (!(remote = lookup_commit_reference(remote_sha1))) {
 577                die("Could not parse remote commit %s (%s)",
 578                    sha1_to_hex(remote_sha1), o->remote_ref);
 579        }
 580        trace_printf("\tremote commit: %.7s\n", sha1_to_hex(remote_sha1));
 581
 582        if (!local && !remote)
 583                die("Cannot merge empty notes ref (%s) into empty notes ref "
 584                    "(%s)", o->remote_ref, o->local_ref);
 585        if (!local) {
 586                /* result == remote commit */
 587                hashcpy(result_sha1, remote_sha1);
 588                goto found_result;
 589        }
 590        if (!remote) {
 591                /* result == local commit */
 592                hashcpy(result_sha1, local_sha1);
 593                goto found_result;
 594        }
 595        assert(local && remote);
 596
 597        /* Find merge bases */
 598        bases = get_merge_bases(local, remote);
 599        if (!bases) {
 600                base_sha1 = null_sha1;
 601                base_tree_sha1 = EMPTY_TREE_SHA1_BIN;
 602                if (o->verbosity >= 4)
 603                        printf("No merge base found; doing history-less merge\n");
 604        } else if (!bases->next) {
 605                base_sha1 = bases->item->object.oid.hash;
 606                base_tree_sha1 = bases->item->tree->object.oid.hash;
 607                if (o->verbosity >= 4)
 608                        printf("One merge base found (%.7s)\n",
 609                                sha1_to_hex(base_sha1));
 610        } else {
 611                /* TODO: How to handle multiple merge-bases? */
 612                base_sha1 = bases->item->object.oid.hash;
 613                base_tree_sha1 = bases->item->tree->object.oid.hash;
 614                if (o->verbosity >= 3)
 615                        printf("Multiple merge bases found. Using the first "
 616                                "(%.7s)\n", sha1_to_hex(base_sha1));
 617        }
 618
 619        if (o->verbosity >= 4)
 620                printf("Merging remote commit %.7s into local commit %.7s with "
 621                        "merge-base %.7s\n", oid_to_hex(&remote->object.oid),
 622                        oid_to_hex(&local->object.oid),
 623                        sha1_to_hex(base_sha1));
 624
 625        if (!hashcmp(remote->object.oid.hash, base_sha1)) {
 626                /* Already merged; result == local commit */
 627                if (o->verbosity >= 2)
 628                        printf("Already up-to-date!\n");
 629                hashcpy(result_sha1, local->object.oid.hash);
 630                goto found_result;
 631        }
 632        if (!hashcmp(local->object.oid.hash, base_sha1)) {
 633                /* Fast-forward; result == remote commit */
 634                if (o->verbosity >= 2)
 635                        printf("Fast-forward\n");
 636                hashcpy(result_sha1, remote->object.oid.hash);
 637                goto found_result;
 638        }
 639
 640        result = merge_from_diffs(o, base_tree_sha1, local->tree->object.oid.hash,
 641                                  remote->tree->object.oid.hash, local_tree);
 642
 643        if (result != 0) { /* non-trivial merge (with or without conflicts) */
 644                /* Commit (partial) result */
 645                struct commit_list *parents = NULL;
 646                commit_list_insert(remote, &parents); /* LIFO order */
 647                commit_list_insert(local, &parents);
 648                create_notes_commit(local_tree, parents,
 649                                    o->commit_msg.buf, o->commit_msg.len,
 650                                    result_sha1);
 651        }
 652
 653found_result:
 654        free_commit_list(bases);
 655        strbuf_release(&(o->commit_msg));
 656        trace_printf("notes_merge(): result = %i, result_sha1 = %.7s\n",
 657               result, sha1_to_hex(result_sha1));
 658        return result;
 659}
 660
 661int notes_merge_commit(struct notes_merge_options *o,
 662                       struct notes_tree *partial_tree,
 663                       struct commit *partial_commit,
 664                       unsigned char *result_sha1)
 665{
 666        /*
 667         * Iterate through files in .git/NOTES_MERGE_WORKTREE and add all
 668         * found notes to 'partial_tree'. Write the updated notes tree to
 669         * the DB, and commit the resulting tree object while reusing the
 670         * commit message and parents from 'partial_commit'.
 671         * Finally store the new commit object SHA1 into 'result_sha1'.
 672         */
 673        DIR *dir;
 674        struct dirent *e;
 675        struct strbuf path = STRBUF_INIT;
 676        const char *buffer = get_commit_buffer(partial_commit, NULL);
 677        const char *msg = strstr(buffer, "\n\n");
 678        int baselen;
 679
 680        strbuf_addstr(&path, git_path(NOTES_MERGE_WORKTREE));
 681        if (o->verbosity >= 3)
 682                printf("Committing notes in notes merge worktree at %s\n",
 683                        path.buf);
 684
 685        if (!msg || msg[2] == '\0')
 686                die("partial notes commit has empty message");
 687        msg += 2;
 688
 689        dir = opendir(path.buf);
 690        if (!dir)
 691                die_errno("could not open %s", path.buf);
 692
 693        strbuf_addch(&path, '/');
 694        baselen = path.len;
 695        while ((e = readdir(dir)) != NULL) {
 696                struct stat st;
 697                unsigned char obj_sha1[20], blob_sha1[20];
 698
 699                if (is_dot_or_dotdot(e->d_name))
 700                        continue;
 701
 702                if (strlen(e->d_name) != 40 || get_sha1_hex(e->d_name, obj_sha1)) {
 703                        if (o->verbosity >= 3)
 704                                printf("Skipping non-SHA1 entry '%s%s'\n",
 705                                        path.buf, e->d_name);
 706                        continue;
 707                }
 708
 709                strbuf_addstr(&path, e->d_name);
 710                /* write file as blob, and add to partial_tree */
 711                if (stat(path.buf, &st))
 712                        die_errno("Failed to stat '%s'", path.buf);
 713                if (index_path(blob_sha1, path.buf, &st, HASH_WRITE_OBJECT))
 714                        die("Failed to write blob object from '%s'", path.buf);
 715                if (add_note(partial_tree, obj_sha1, blob_sha1, NULL))
 716                        die("Failed to add resolved note '%s' to notes tree",
 717                            path.buf);
 718                if (o->verbosity >= 4)
 719                        printf("Added resolved note for object %s: %s\n",
 720                                sha1_to_hex(obj_sha1), sha1_to_hex(blob_sha1));
 721                strbuf_setlen(&path, baselen);
 722        }
 723
 724        create_notes_commit(partial_tree, partial_commit->parents,
 725                            msg, strlen(msg), result_sha1);
 726        unuse_commit_buffer(partial_commit, buffer);
 727        if (o->verbosity >= 4)
 728                printf("Finalized notes merge commit: %s\n",
 729                        sha1_to_hex(result_sha1));
 730        strbuf_release(&path);
 731        closedir(dir);
 732        return 0;
 733}
 734
 735int notes_merge_abort(struct notes_merge_options *o)
 736{
 737        /*
 738         * Remove all files within .git/NOTES_MERGE_WORKTREE. We do not remove
 739         * the .git/NOTES_MERGE_WORKTREE directory itself, since it might be
 740         * the current working directory of the user.
 741         */
 742        struct strbuf buf = STRBUF_INIT;
 743        int ret;
 744
 745        strbuf_addstr(&buf, git_path(NOTES_MERGE_WORKTREE));
 746        if (o->verbosity >= 3)
 747                printf("Removing notes merge worktree at %s/*\n", buf.buf);
 748        ret = remove_dir_recursively(&buf, REMOVE_DIR_KEEP_TOPLEVEL);
 749        strbuf_release(&buf);
 750        return ret;
 751}