notes-merge.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "refs.h"
   4 #include "object-store.h"
   5 #include "repository.h"
   6 #include "diff.h"
   7 #include "diffcore.h"
   8 #include "hex.h"
   9 #include "xdiff-interface.h"
  10 #include "ll-merge.h"
  11 #include "dir.h"
  12 #include "notes.h"
  13 #include "notes-merge.h"
  14 #include "strbuf.h"
  15 #include "notes-utils.h"
  16 #include "commit-reach.h"
  17
  18 struct notes_merge_pair {
  19         struct object_id obj, base, local, remote;
  20 };
  21
  22 void init_notes_merge_options(struct repository *r,
  23                               struct notes_merge_options *o)
  24 {
  25         memset(o, 0, sizeof(struct notes_merge_options));
  26         strbuf_init(&(o->commit_msg), 0);
  27         o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
  28         o->repo = r;
  29 }
  30
  31 static int path_to_oid(const char *path, struct object_id *oid)
  32 {
  33         char hex_oid[GIT_MAX_HEXSZ];
  34         int i = 0;
  35         while (*path && i < the_hash_algo->hexsz) {
  36                 if (*path != '/')
  37                         hex_oid[i++] = *path;
  38                 path++;
  39         }
  40         if (*path || i != the_hash_algo->hexsz)
  41                 return -1;
  42         return get_oid_hex(hex_oid, oid);
  43 }
  44
  45 static int verify_notes_filepair(struct diff_filepair *p, struct object_id *oid)
  46 {
  47         switch (p->status) {
  48         case DIFF_STATUS_MODIFIED:
  49                 assert(p->one->mode == p->two->mode);
  50                 assert(!is_null_oid(&p->one->oid));
  51                 assert(!is_null_oid(&p->two->oid));
  52                 break;
  53         case DIFF_STATUS_ADDED:
  54                 assert(is_null_oid(&p->one->oid));
  55                 break;
  56         case DIFF_STATUS_DELETED:
  57                 assert(is_null_oid(&p->two->oid));
  58                 break;
  59         default:
  60                 return -1;
  61         }
  62         assert(!strcmp(p->one->path, p->two->path));
  63         return path_to_oid(p->one->path, oid);
  64 }
  65
  66 static struct notes_merge_pair *find_notes_merge_pair_pos(
  67                 struct notes_merge_pair *list, int len, struct object_id *obj,
  68                 int insert_new, int *occupied)
  69 {
  70         /*
  71          * Both diff_tree_remote() and diff_tree_local() tend to process
  72          * merge_pairs in ascending order. Therefore, cache last returned
  73          * index, and search sequentially from there until the appropriate
  74          * position is found.
  75          *
  76          * Since inserts only happen from diff_tree_remote() (which mainly
  77          * _appends_), we don't care that inserting into the middle of the
  78          * list is expensive (using memmove()).
  79          */
  80         static int last_index;
  81         int i = last_index < len ? last_index : len - 1;
  82         int prev_cmp = 0, cmp = -1;
  83         while (i >= 0 && i < len) {
  84                 cmp = oidcmp(obj, &list[i].obj);
  85                 if (!cmp) /* obj belongs @ i */
  86                         break;
  87                 else if (cmp < 0 && prev_cmp <= 0) /* obj belongs < i */
  88                         i--;
  89                 else if (cmp < 0) /* obj belongs between i-1 and i */
  90                         break;
  91                 else if (cmp > 0 && prev_cmp >= 0) /* obj belongs > i */
  92                         i++;
  93                 else /* if (cmp > 0) */ { /* obj belongs between i and i+1 */
  94                         i++;
  95                         break;
  96                 }
  97                 prev_cmp = cmp;
  98         }
  99         if (i < 0)
 100                 i = 0;
 101         /* obj belongs at, or immediately preceding, index i (0 <= i <= len) */
 102
 103         if (!cmp)
 104                 *occupied = 1;
 105         else {
 106                 *occupied = 0;
 107                 if (insert_new && i < len) {
 108                         MOVE_ARRAY(list + i + 1, list + i, len - i);
 109                         memset(list + i, 0, sizeof(struct notes_merge_pair));
 110                 }
 111         }
 112         last_index = i;
 113         return list + i;
 114 }
 115
 116 static struct object_id uninitialized = {
 117         .hash =
 118         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" \
 119         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
 120 };
 121
 122 static struct notes_merge_pair *diff_tree_remote(struct notes_merge_options *o,
 123                                                  const struct object_id *base,
 124                                                  const struct object_id *remote,
 125                                                  int *num_changes)
 126 {
 127         struct diff_options opt;
 128         struct notes_merge_pair *changes;
 129         int i, len = 0;
 130
 131         trace_printf("\tdiff_tree_remote(base = %.7s, remote = %.7s)\n",
 132                oid_to_hex(base), oid_to_hex(remote));
 133
 134         repo_diff_setup(o->repo, &opt);
 135         opt.flags.recursive = 1;
 136         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 137         diff_setup_done(&opt);
 138         diff_tree_oid(base, remote, "", &opt);
 139         diffcore_std(&opt);
 140
 141         CALLOC_ARRAY(changes, diff_queued_diff.nr);
 142
 143         for (i = 0; i < diff_queued_diff.nr; i++) {
 144                 struct diff_filepair *p = diff_queued_diff.queue[i];
 145                 struct notes_merge_pair *mp;
 146                 int occupied;
 147                 struct object_id obj;
 148
 149                 if (verify_notes_filepair(p, &obj)) {
 150                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 151                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 152                                p->status, oid_to_hex(&p->one->oid),
 153                                oid_to_hex(&p->two->oid));
 154                         continue;
 155                 }
 156                 mp = find_notes_merge_pair_pos(changes, len, &obj, 1, &occupied);
 157                 if (occupied) {
 158                         /* We've found an addition/deletion pair */
 159                         assert(oideq(&mp->obj, &obj));
 160                         if (is_null_oid(&p->one->oid)) { /* addition */
 161                                 assert(is_null_oid(&mp->remote));
 162                                 oidcpy(&mp->remote, &p->two->oid);
 163                         } else if (is_null_oid(&p->two->oid)) { /* deletion */
 164                                 assert(is_null_oid(&mp->base));
 165                                 oidcpy(&mp->base, &p->one->oid);
 166                         } else
 167                                 assert(!"Invalid existing change recorded");
 168                 } else {
 169                         oidcpy(&mp->obj, &obj);
 170                         oidcpy(&mp->base, &p->one->oid);
 171                         oidcpy(&mp->local, &uninitialized);
 172                         oidcpy(&mp->remote, &p->two->oid);
 173                         len++;
 174                 }
 175                 trace_printf("\t\tStored remote change for %s: %.7s -> %.7s\n",
 176                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
 177                        oid_to_hex(&mp->remote));
 178         }
 179         diff_flush(&opt);
 180
 181         *num_changes = len;
 182         return changes;
 183 }
 184
 185 static void diff_tree_local(struct notes_merge_options *o,
 186                             struct notes_merge_pair *changes, int len,
 187                             const struct object_id *base,
 188                             const struct object_id *local)
 189 {
 190         struct diff_options opt;
 191         int i;
 192
 193         trace_printf("\tdiff_tree_local(len = %i, base = %.7s, local = %.7s)\n",
 194                len, oid_to_hex(base), oid_to_hex(local));
 195
 196         repo_diff_setup(o->repo, &opt);
 197         opt.flags.recursive = 1;
 198         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 199         diff_setup_done(&opt);
 200         diff_tree_oid(base, local, "", &opt);
 201         diffcore_std(&opt);
 202
 203         for (i = 0; i < diff_queued_diff.nr; i++) {
 204                 struct diff_filepair *p = diff_queued_diff.queue[i];
 205                 struct notes_merge_pair *mp;
 206                 int match;
 207                 struct object_id obj;
 208
 209                 if (verify_notes_filepair(p, &obj)) {
 210                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 211                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 212                                p->status, oid_to_hex(&p->one->oid),
 213                                oid_to_hex(&p->two->oid));
 214                         continue;
 215                 }
 216                 mp = find_notes_merge_pair_pos(changes, len, &obj, 0, &match);
 217                 if (!match) {
 218                         trace_printf("\t\tIgnoring local-only change for %s: "
 219                                "%.7s -> %.7s\n", oid_to_hex(&obj),
 220                                oid_to_hex(&p->one->oid),
 221                                oid_to_hex(&p->two->oid));
 222                         continue;
 223                 }
 224
 225                 assert(oideq(&mp->obj, &obj));
 226                 if (is_null_oid(&p->two->oid)) { /* deletion */
 227                         /*
 228                          * Either this is a true deletion (1), or it is part
 229                          * of an A/D pair (2), or D/A pair (3):
 230                          *
 231                          * (1) mp->local is uninitialized; set it to null_sha1
 232                          * (2) mp->local is not uninitialized; don't touch it
 233                          * (3) mp->local is uninitialized; set it to null_sha1
 234                          *     (will be overwritten by following addition)
 235                          */
 236                         if (oideq(&mp->local, &uninitialized))
 237                                 oidclr(&mp->local);
 238                 } else if (is_null_oid(&p->one->oid)) { /* addition */
 239                         /*
 240                          * Either this is a true addition (1), or it is part
 241                          * of an A/D pair (2), or D/A pair (3):
 242                          *
 243                          * (1) mp->local is uninitialized; set to p->two->sha1
 244                          * (2) mp->local is uninitialized; set to p->two->sha1
 245                          * (3) mp->local is null_sha1;     set to p->two->sha1
 246                          */
 247                         assert(is_null_oid(&mp->local) ||
 248                                oideq(&mp->local, &uninitialized));
 249                         oidcpy(&mp->local, &p->two->oid);
 250                 } else { /* modification */
 251                         /*
 252                          * This is a true modification. p->one->sha1 shall
 253                          * match mp->base, and mp->local shall be uninitialized.
 254                          * Set mp->local to p->two->sha1.
 255                          */
 256                         assert(oideq(&p->one->oid, &mp->base));
 257                         assert(oideq(&mp->local, &uninitialized));
 258                         oidcpy(&mp->local, &p->two->oid);
 259                 }
 260                 trace_printf("\t\tStored local change for %s: %.7s -> %.7s\n",
 261                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
 262                        oid_to_hex(&mp->local));
 263         }
 264         diff_flush(&opt);
 265 }
 266
 267 static void check_notes_merge_worktree(struct notes_merge_options *o)
 268 {
 269         if (!o->has_worktree) {
 270                 /*
 271                  * Must establish NOTES_MERGE_WORKTREE.
 272                  * Abort if NOTES_MERGE_WORKTREE already exists
 273                  */
 274                 if (file_exists(git_path(NOTES_MERGE_WORKTREE)) &&
 275                     !is_empty_dir(git_path(NOTES_MERGE_WORKTREE))) {
 276                         if (advice_enabled(ADVICE_RESOLVE_CONFLICT))
 277                                 die(_("You have not concluded your previous "
 278                                     "notes merge (%s exists).\nPlease, use "
 279                                     "'git notes merge --commit' or 'git notes "
 280                                     "merge --abort' to commit/abort the "
 281                                     "previous merge before you start a new "
 282                                     "notes merge."), git_path("NOTES_MERGE_*"));
 283                         else
 284                                 die(_("You have not concluded your notes merge "
 285                                     "(%s exists)."), git_path("NOTES_MERGE_*"));
 286                 }
 287
 288                 if (safe_create_leading_directories_const(git_path(
 289                                 NOTES_MERGE_WORKTREE "/.test")))
 290                         die_errno("unable to create directory %s",
 291                                   git_path(NOTES_MERGE_WORKTREE));
 292                 o->has_worktree = 1;
 293         } else if (!file_exists(git_path(NOTES_MERGE_WORKTREE)))
 294                 /* NOTES_MERGE_WORKTREE should already be established */
 295                 die("missing '%s'. This should not happen",
 296                     git_path(NOTES_MERGE_WORKTREE));
 297 }
 298
 299 static void write_buf_to_worktree(const struct object_id *obj,
 300                                   const char *buf, unsigned long size)
 301 {
 302         int fd;
 303         char *path = git_pathdup(NOTES_MERGE_WORKTREE "/%s", oid_to_hex(obj));
 304         if (safe_create_leading_directories_const(path))
 305                 die_errno("unable to create directory for '%s'", path);
 306
 307         fd = xopen(path, O_WRONLY | O_EXCL | O_CREAT, 0666);
 308
 309         while (size > 0) {
 310                 ssize_t ret = write_in_full(fd, buf, size);
 311                 if (ret < 0) {
 312                         /* Ignore epipe */
 313                         if (errno == EPIPE)
 314                                 break;
 315                         die_errno("notes-merge");
 316                 }
 317                 size -= ret;
 318                 buf += ret;
 319         }
 320
 321         close(fd);
 322         free(path);
 323 }
 324
 325 static void write_note_to_worktree(const struct object_id *obj,
 326                                    const struct object_id *note)
 327 {
 328         enum object_type type;
 329         unsigned long size;
 330         void *buf = read_object_file(note, &type, &size);
 331
 332         if (!buf)
 333                 die("cannot read note %s for object %s",
 334                     oid_to_hex(note), oid_to_hex(obj));
 335         if (type != OBJ_BLOB)
 336                 die("blob expected in note %s for object %s",
 337                     oid_to_hex(note), oid_to_hex(obj));
 338         write_buf_to_worktree(obj, buf, size);
 339         free(buf);
 340 }
 341
 342 static int ll_merge_in_worktree(struct notes_merge_options *o,
 343                                 struct notes_merge_pair *p)
 344 {
 345         mmbuffer_t result_buf;
 346         mmfile_t base, local, remote;
 347         enum ll_merge_result status;
 348
 349         read_mmblob(&base, &p->base);
 350         read_mmblob(&local, &p->local);
 351         read_mmblob(&remote, &p->remote);
 352
 353         status = ll_merge(&result_buf, oid_to_hex(&p->obj), &base, NULL,
 354                           &local, o->local_ref, &remote, o->remote_ref,
 355                           o->repo->index, NULL);
 356
 357         free(base.ptr);
 358         free(local.ptr);
 359         free(remote.ptr);
 360
 361         if (status == LL_MERGE_BINARY_CONFLICT)
 362                 warning("Cannot merge binary files: %s (%s vs. %s)",
 363                         oid_to_hex(&p->obj), o->local_ref, o->remote_ref);
 364         if ((status < 0) || !result_buf.ptr)
 365                 die("Failed to execute internal merge");
 366
 367         write_buf_to_worktree(&p->obj, result_buf.ptr, result_buf.size);
 368         free(result_buf.ptr);
 369
 370         return status;
 371 }
 372
 373 static int merge_one_change_manual(struct notes_merge_options *o,
 374                                    struct notes_merge_pair *p,
 375                                    struct notes_tree *t)
 376 {
 377         const char *lref = o->local_ref ? o->local_ref : "local version";
 378         const char *rref = o->remote_ref ? o->remote_ref : "remote version";
 379
 380         trace_printf("\t\t\tmerge_one_change_manual(obj = %.7s, base = %.7s, "
 381                "local = %.7s, remote = %.7s)\n",
 382                oid_to_hex(&p->obj), oid_to_hex(&p->base),
 383                oid_to_hex(&p->local), oid_to_hex(&p->remote));
 384
 385         /* add "Conflicts:" section to commit message first time through */
 386         if (!o->has_worktree)
 387                 strbuf_addstr(&(o->commit_msg), "\n\nConflicts:\n");
 388
 389         strbuf_addf(&(o->commit_msg), "\t%s\n", oid_to_hex(&p->obj));
 390
 391         if (o->verbosity >= 2)
 392                 printf("Auto-merging notes for %s\n", oid_to_hex(&p->obj));
 393         check_notes_merge_worktree(o);
 394         if (is_null_oid(&p->local)) {
 395                 /* D/F conflict, checkout p->remote */
 396                 assert(!is_null_oid(&p->remote));
 397                 if (o->verbosity >= 1)
 398                         printf("CONFLICT (delete/modify): Notes for object %s "
 399                                 "deleted in %s and modified in %s. Version from %s "
 400                                 "left in tree.\n",
 401                                 oid_to_hex(&p->obj), lref, rref, rref);
 402                 write_note_to_worktree(&p->obj, &p->remote);
 403         } else if (is_null_oid(&p->remote)) {
 404                 /* D/F conflict, checkout p->local */
 405                 assert(!is_null_oid(&p->local));
 406                 if (o->verbosity >= 1)
 407                         printf("CONFLICT (delete/modify): Notes for object %s "
 408                                 "deleted in %s and modified in %s. Version from %s "
 409                                 "left in tree.\n",
 410                                 oid_to_hex(&p->obj), rref, lref, lref);
 411                 write_note_to_worktree(&p->obj, &p->local);
 412         } else {
 413                 /* "regular" conflict, checkout result of ll_merge() */
 414                 const char *reason = "content";
 415                 if (is_null_oid(&p->base))
 416                         reason = "add/add";
 417                 assert(!is_null_oid(&p->local));
 418                 assert(!is_null_oid(&p->remote));
 419                 if (o->verbosity >= 1)
 420                         printf("CONFLICT (%s): Merge conflict in notes for "
 421                                 "object %s\n", reason,
 422                                 oid_to_hex(&p->obj));
 423                 ll_merge_in_worktree(o, p);
 424         }
 425
 426         trace_printf("\t\t\tremoving from partial merge result\n");
 427         remove_note(t, p->obj.hash);
 428
 429         return 1;
 430 }
 431
 432 static int merge_one_change(struct notes_merge_options *o,
 433                             struct notes_merge_pair *p, struct notes_tree *t)
 434 {
 435         /*
 436          * Return 0 if change is successfully resolved (stored in notes_tree).
 437          * Return 1 is change results in a conflict (NOT stored in notes_tree,
 438          * but instead written to NOTES_MERGE_WORKTREE with conflict markers).
 439          */
 440         switch (o->strategy) {
 441         case NOTES_MERGE_RESOLVE_MANUAL:
 442                 return merge_one_change_manual(o, p, t);
 443         case NOTES_MERGE_RESOLVE_OURS:
 444                 if (o->verbosity >= 2)
 445                         printf("Using local notes for %s\n",
 446                                                 oid_to_hex(&p->obj));
 447                 /* nothing to do */
 448                 return 0;
 449         case NOTES_MERGE_RESOLVE_THEIRS:
 450                 if (o->verbosity >= 2)
 451                         printf("Using remote notes for %s\n",
 452                                                 oid_to_hex(&p->obj));
 453                 if (add_note(t, &p->obj, &p->remote, combine_notes_overwrite))
 454                         BUG("combine_notes_overwrite failed");
 455                 return 0;
 456         case NOTES_MERGE_RESOLVE_UNION:
 457                 if (o->verbosity >= 2)
 458                         printf("Concatenating local and remote notes for %s\n",
 459                                                         oid_to_hex(&p->obj));
 460                 if (add_note(t, &p->obj, &p->remote, combine_notes_concatenate))
 461                         die("failed to concatenate notes "
 462                             "(combine_notes_concatenate)");
 463                 return 0;
 464         case NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ:
 465                 if (o->verbosity >= 2)
 466                         printf("Concatenating unique lines in local and remote "
 467                                 "notes for %s\n", oid_to_hex(&p->obj));
 468                 if (add_note(t, &p->obj, &p->remote, combine_notes_cat_sort_uniq))
 469                         die("failed to concatenate notes "
 470                             "(combine_notes_cat_sort_uniq)");
 471                 return 0;
 472         }
 473         die("Unknown strategy (%i).", o->strategy);
 474 }
 475
 476 static int merge_changes(struct notes_merge_options *o,
 477                          struct notes_merge_pair *changes, int *num_changes,
 478                          struct notes_tree *t)
 479 {
 480         int i, conflicts = 0;
 481
 482         trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
 483         for (i = 0; i < *num_changes; i++) {
 484                 struct notes_merge_pair *p = changes + i;
 485                 trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
 486                        oid_to_hex(&p->obj), oid_to_hex(&p->base),
 487                        oid_to_hex(&p->local),
 488                        oid_to_hex(&p->remote));
 489
 490                 if (oideq(&p->base, &p->remote)) {
 491                         /* no remote change; nothing to do */
 492                         trace_printf("\t\t\tskipping (no remote change)\n");
 493                 } else if (oideq(&p->local, &p->remote)) {
 494                         /* same change in local and remote; nothing to do */
 495                         trace_printf("\t\t\tskipping (local == remote)\n");
 496                 } else if (oideq(&p->local, &uninitialized) ||
 497                            oideq(&p->local, &p->base)) {
 498                         /* no local change; adopt remote change */
 499                         trace_printf("\t\t\tno local change, adopted remote\n");
 500                         if (add_note(t, &p->obj, &p->remote,
 501                                      combine_notes_overwrite))
 502                                 BUG("combine_notes_overwrite failed");
 503                 } else {
 504                         /* need file-level merge between local and remote */
 505                         trace_printf("\t\t\tneed content-level merge\n");
 506                         conflicts += merge_one_change(o, p, t);
 507                 }
 508         }
 509
 510         return conflicts;
 511 }
 512
 513 static int merge_from_diffs(struct notes_merge_options *o,
 514                             const struct object_id *base,
 515                             const struct object_id *local,
 516                             const struct object_id *remote,
 517                             struct notes_tree *t)
 518 {
 519         struct notes_merge_pair *changes;
 520         int num_changes, conflicts;
 521
 522         trace_printf("\tmerge_from_diffs(base = %.7s, local = %.7s, "
 523                "remote = %.7s)\n", oid_to_hex(base), oid_to_hex(local),
 524                oid_to_hex(remote));
 525
 526         changes = diff_tree_remote(o, base, remote, &num_changes);
 527         diff_tree_local(o, changes, num_changes, base, local);
 528
 529         conflicts = merge_changes(o, changes, &num_changes, t);
 530         free(changes);
 531
 532         if (o->verbosity >= 4)
 533                 printf(t->dirty ?
 534                        "Merge result: %i unmerged notes and a dirty notes tree\n" :
 535                        "Merge result: %i unmerged notes and a clean notes tree\n",
 536                        conflicts);
 537
 538         return conflicts ? -1 : 1;
 539 }
 540
 541 int notes_merge(struct notes_merge_options *o,
 542                 struct notes_tree *local_tree,
 543                 struct object_id *result_oid)
 544 {
 545         struct object_id local_oid, remote_oid;
 546         struct commit *local, *remote;
 547         struct commit_list *bases = NULL;
 548         const struct object_id *base_oid, *base_tree_oid;
 549         int result = 0;
 550
 551         assert(o->local_ref && o->remote_ref);
 552         assert(!strcmp(o->local_ref, local_tree->ref));
 553         oidclr(result_oid);
 554
 555         trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
 556                o->local_ref, o->remote_ref);
 557
 558         /* Dereference o->local_ref into local_sha1 */
 559         if (read_ref_full(o->local_ref, 0, &local_oid, NULL))
 560                 die("Failed to resolve local notes ref '%s'", o->local_ref);
 561         else if (!check_refname_format(o->local_ref, 0) &&
 562                 is_null_oid(&local_oid))
 563                 local = NULL; /* local_oid == null_oid indicates unborn ref */
 564         else if (!(local = lookup_commit_reference(o->repo, &local_oid)))
 565                 die("Could not parse local commit %s (%s)",
 566                     oid_to_hex(&local_oid), o->local_ref);
 567         trace_printf("\tlocal commit: %.7s\n", oid_to_hex(&local_oid));
 568
 569         /* Dereference o->remote_ref into remote_oid */
 570         if (get_oid(o->remote_ref, &remote_oid)) {
 571                 /*
 572                  * Failed to get remote_oid. If o->remote_ref looks like an
 573                  * unborn ref, perform the merge using an empty notes tree.
 574                  */
 575                 if (!check_refname_format(o->remote_ref, 0)) {
 576                         oidclr(&remote_oid);
 577                         remote = NULL;
 578                 } else {
 579                         die("Failed to resolve remote notes ref '%s'",
 580                             o->remote_ref);
 581                 }
 582         } else if (!(remote = lookup_commit_reference(o->repo, &remote_oid))) {
 583                 die("Could not parse remote commit %s (%s)",
 584                     oid_to_hex(&remote_oid), o->remote_ref);
 585         }
 586         trace_printf("\tremote commit: %.7s\n", oid_to_hex(&remote_oid));
 587
 588         if (!local && !remote)
 589                 die("Cannot merge empty notes ref (%s) into empty notes ref "
 590                     "(%s)", o->remote_ref, o->local_ref);
 591         if (!local) {
 592                 /* result == remote commit */
 593                 oidcpy(result_oid, &remote_oid);
 594                 goto found_result;
 595         }
 596         if (!remote) {
 597                 /* result == local commit */
 598                 oidcpy(result_oid, &local_oid);
 599                 goto found_result;
 600         }
 601         assert(local && remote);
 602
 603         /* Find merge bases */
 604         bases = get_merge_bases(local, remote);
 605         if (!bases) {
 606                 base_oid = null_oid();
 607                 base_tree_oid = the_hash_algo->empty_tree;
 608                 if (o->verbosity >= 4)
 609                         printf("No merge base found; doing history-less merge\n");
 610         } else if (!bases->next) {
 611                 base_oid = &bases->item->object.oid;
 612                 base_tree_oid = get_commit_tree_oid(bases->item);
 613                 if (o->verbosity >= 4)
 614                         printf("One merge base found (%.7s)\n",
 615                                oid_to_hex(base_oid));
 616         } else {
 617                 /* TODO: How to handle multiple merge-bases? */
 618                 base_oid = &bases->item->object.oid;
 619                 base_tree_oid = get_commit_tree_oid(bases->item);
 620                 if (o->verbosity >= 3)
 621                         printf("Multiple merge bases found. Using the first "
 622                                 "(%.7s)\n", oid_to_hex(base_oid));
 623         }
 624
 625         if (o->verbosity >= 4)
 626                 printf("Merging remote commit %.7s into local commit %.7s with "
 627                         "merge-base %.7s\n", oid_to_hex(&remote->object.oid),
 628                         oid_to_hex(&local->object.oid),
 629                         oid_to_hex(base_oid));
 630
 631         if (oideq(&remote->object.oid, base_oid)) {
 632                 /* Already merged; result == local commit */
 633                 if (o->verbosity >= 2)
 634                         printf_ln("Already up to date.");
 635                 oidcpy(result_oid, &local->object.oid);
 636                 goto found_result;
 637         }
 638         if (oideq(&local->object.oid, base_oid)) {
 639                 /* Fast-forward; result == remote commit */
 640                 if (o->verbosity >= 2)
 641                         printf("Fast-forward\n");
 642                 oidcpy(result_oid, &remote->object.oid);
 643                 goto found_result;
 644         }
 645
 646         result = merge_from_diffs(o, base_tree_oid,
 647                                   get_commit_tree_oid(local),
 648                                   get_commit_tree_oid(remote), local_tree);
 649
 650         if (result != 0) { /* non-trivial merge (with or without conflicts) */
 651                 /* Commit (partial) result */
 652                 struct commit_list *parents = NULL;
 653                 commit_list_insert(remote, &parents); /* LIFO order */
 654                 commit_list_insert(local, &parents);
 655                 create_notes_commit(o->repo, local_tree, parents, o->commit_msg.buf,
 656                                     o->commit_msg.len, result_oid);
 657         }
 658
 659 found_result:
 660         free_commit_list(bases);
 661         strbuf_release(&(o->commit_msg));
 662         trace_printf("notes_merge(): result = %i, result_oid = %.7s\n",
 663                result, oid_to_hex(result_oid));
 664         return result;
 665 }
 666
 667 int notes_merge_commit(struct notes_merge_options *o,
 668                        struct notes_tree *partial_tree,
 669                        struct commit *partial_commit,
 670                        struct object_id *result_oid)
 671 {
 672         /*
 673          * Iterate through files in .git/NOTES_MERGE_WORKTREE and add all
 674          * found notes to 'partial_tree'. Write the updated notes tree to
 675          * the DB, and commit the resulting tree object while reusing the
 676          * commit message and parents from 'partial_commit'.
 677          * Finally store the new commit object OID into 'result_oid'.
 678          */
 679         DIR *dir;
 680         struct dirent *e;
 681         struct strbuf path = STRBUF_INIT;
 682         const char *buffer = get_commit_buffer(partial_commit, NULL);
 683         const char *msg = strstr(buffer, "\n\n");
 684         int baselen;
 685
 686         git_path_buf(&path, NOTES_MERGE_WORKTREE);
 687         if (o->verbosity >= 3)
 688                 printf("Committing notes in notes merge worktree at %s\n",
 689                         path.buf);
 690
 691         if (!msg || msg[2] == '\0')
 692                 die("partial notes commit has empty message");
 693         msg += 2;
 694
 695         dir = opendir(path.buf);
 696         if (!dir)
 697                 die_errno("could not open %s", path.buf);
 698
 699         strbuf_addch(&path, '/');
 700         baselen = path.len;
 701         while ((e = readdir_skip_dot_and_dotdot(dir)) != NULL) {
 702                 struct stat st;
 703                 struct object_id obj_oid, blob_oid;
 704
 705                 if (get_oid_hex(e->d_name, &obj_oid)) {
 706                         if (o->verbosity >= 3)
 707                                 printf("Skipping non-SHA1 entry '%s%s'\n",
 708                                         path.buf, e->d_name);
 709                         continue;
 710                 }
 711
 712                 strbuf_addstr(&path, e->d_name);
 713                 /* write file as blob, and add to partial_tree */
 714                 if (stat(path.buf, &st))
 715                         die_errno("Failed to stat '%s'", path.buf);
 716                 if (index_path(o->repo->index, &blob_oid, path.buf, &st, HASH_WRITE_OBJECT))
 717                         die("Failed to write blob object from '%s'", path.buf);
 718                 if (add_note(partial_tree, &obj_oid, &blob_oid, NULL))
 719                         die("Failed to add resolved note '%s' to notes tree",
 720                             path.buf);
 721                 if (o->verbosity >= 4)
 722                         printf("Added resolved note for object %s: %s\n",
 723                                 oid_to_hex(&obj_oid), oid_to_hex(&blob_oid));
 724                 strbuf_setlen(&path, baselen);
 725         }
 726
 727         create_notes_commit(o->repo, partial_tree, partial_commit->parents, msg,
 728                             strlen(msg), result_oid);
 729         unuse_commit_buffer(partial_commit, buffer);
 730         if (o->verbosity >= 4)
 731                 printf("Finalized notes merge commit: %s\n",
 732                         oid_to_hex(result_oid));
 733         strbuf_release(&path);
 734         closedir(dir);
 735         return 0;
 736 }
 737
 738 int notes_merge_abort(struct notes_merge_options *o)
 739 {
 740         /*
 741          * Remove all files within .git/NOTES_MERGE_WORKTREE. We do not remove
 742          * the .git/NOTES_MERGE_WORKTREE directory itself, since it might be
 743          * the current working directory of the user.
 744          */
 745         struct strbuf buf = STRBUF_INIT;
 746         int ret;
 747
 748         git_path_buf(&buf, NOTES_MERGE_WORKTREE);
 749         if (o->verbosity >= 3)
 750                 printf("Removing notes merge worktree at %s/*\n", buf.buf);
 751         ret = remove_dir_recursively(&buf, REMOVE_DIR_KEEP_TOPLEVEL);
 752         strbuf_release(&buf);
 753         return ret;
 754 }