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 "xdiff-interface.h"
   9 #include "ll-merge.h"
  10 #include "dir.h"
  11 #include "notes.h"
  12 #include "notes-merge.h"
  13 #include "strbuf.h"
  14 #include "notes-utils.h"
  15 #include "commit-reach.h"
  16
  17 struct notes_merge_pair {
  18         struct object_id obj, base, local, remote;
  19 };
  20
  21 void init_notes_merge_options(struct notes_merge_options *o)
  22 {
  23         memset(o, 0, sizeof(struct notes_merge_options));
  24         strbuf_init(&(o->commit_msg), 0);
  25         o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
  26 }
  27
  28 static int path_to_oid(const char *path, struct object_id *oid)
  29 {
  30         char hex_oid[GIT_SHA1_HEXSZ];
  31         int i = 0;
  32         while (*path && i < GIT_SHA1_HEXSZ) {
  33                 if (*path != '/')
  34                         hex_oid[i++] = *path;
  35                 path++;
  36         }
  37         if (*path || i != GIT_SHA1_HEXSZ)
  38                 return -1;
  39         return get_oid_hex(hex_oid, oid);
  40 }
  41
  42 static int verify_notes_filepair(struct diff_filepair *p, struct object_id *oid)
  43 {
  44         switch (p->status) {
  45         case DIFF_STATUS_MODIFIED:
  46                 assert(p->one->mode == p->two->mode);
  47                 assert(!is_null_oid(&p->one->oid));
  48                 assert(!is_null_oid(&p->two->oid));
  49                 break;
  50         case DIFF_STATUS_ADDED:
  51                 assert(is_null_oid(&p->one->oid));
  52                 break;
  53         case DIFF_STATUS_DELETED:
  54                 assert(is_null_oid(&p->two->oid));
  55                 break;
  56         default:
  57                 return -1;
  58         }
  59         assert(!strcmp(p->one->path, p->two->path));
  60         return path_to_oid(p->one->path, oid);
  61 }
  62
  63 static struct notes_merge_pair *find_notes_merge_pair_pos(
  64                 struct notes_merge_pair *list, int len, struct object_id *obj,
  65                 int insert_new, int *occupied)
  66 {
  67         /*
  68          * Both diff_tree_remote() and diff_tree_local() tend to process
  69          * merge_pairs in ascending order. Therefore, cache last returned
  70          * index, and search sequentially from there until the appropriate
  71          * position is found.
  72          *
  73          * Since inserts only happen from diff_tree_remote() (which mainly
  74          * _appends_), we don't care that inserting into the middle of the
  75          * list is expensive (using memmove()).
  76          */
  77         static int last_index;
  78         int i = last_index < len ? last_index : len - 1;
  79         int prev_cmp = 0, cmp = -1;
  80         while (i >= 0 && i < len) {
  81                 cmp = oidcmp(obj, &list[i].obj);
  82                 if (!cmp) /* obj belongs @ i */
  83                         break;
  84                 else if (cmp < 0 && prev_cmp <= 0) /* obj belongs < i */
  85                         i--;
  86                 else if (cmp < 0) /* obj belongs between i-1 and i */
  87                         break;
  88                 else if (cmp > 0 && prev_cmp >= 0) /* obj belongs > i */
  89                         i++;
  90                 else /* if (cmp > 0) */ { /* obj belongs between i and i+1 */
  91                         i++;
  92                         break;
  93                 }
  94                 prev_cmp = cmp;
  95         }
  96         if (i < 0)
  97                 i = 0;
  98         /* obj belongs at, or immediately preceding, index i (0 <= i <= len) */
  99
 100         if (!cmp)
 101                 *occupied = 1;
 102         else {
 103                 *occupied = 0;
 104                 if (insert_new && i < len) {
 105                         MOVE_ARRAY(list + i + 1, list + i, len - i);
 106                         memset(list + i, 0, sizeof(struct notes_merge_pair));
 107                 }
 108         }
 109         last_index = i;
 110         return list + i;
 111 }
 112
 113 static struct object_id uninitialized = {
 114         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" \
 115         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
 116 };
 117
 118 static struct notes_merge_pair *diff_tree_remote(struct notes_merge_options *o,
 119                                                  const struct object_id *base,
 120                                                  const struct object_id *remote,
 121                                                  int *num_changes)
 122 {
 123         struct diff_options opt;
 124         struct notes_merge_pair *changes;
 125         int i, len = 0;
 126
 127         trace_printf("\tdiff_tree_remote(base = %.7s, remote = %.7s)\n",
 128                oid_to_hex(base), oid_to_hex(remote));
 129
 130         repo_diff_setup(the_repository, &opt);
 131         opt.flags.recursive = 1;
 132         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 133         diff_setup_done(&opt);
 134         diff_tree_oid(base, remote, "", &opt);
 135         diffcore_std(&opt);
 136
 137         changes = xcalloc(diff_queued_diff.nr, sizeof(struct notes_merge_pair));
 138
 139         for (i = 0; i < diff_queued_diff.nr; i++) {
 140                 struct diff_filepair *p = diff_queued_diff.queue[i];
 141                 struct notes_merge_pair *mp;
 142                 int occupied;
 143                 struct object_id obj;
 144
 145                 if (verify_notes_filepair(p, &obj)) {
 146                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 147                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 148                                p->status, oid_to_hex(&p->one->oid),
 149                                oid_to_hex(&p->two->oid));
 150                         continue;
 151                 }
 152                 mp = find_notes_merge_pair_pos(changes, len, &obj, 1, &occupied);
 153                 if (occupied) {
 154                         /* We've found an addition/deletion pair */
 155                         assert(oideq(&mp->obj, &obj));
 156                         if (is_null_oid(&p->one->oid)) { /* addition */
 157                                 assert(is_null_oid(&mp->remote));
 158                                 oidcpy(&mp->remote, &p->two->oid);
 159                         } else if (is_null_oid(&p->two->oid)) { /* deletion */
 160                                 assert(is_null_oid(&mp->base));
 161                                 oidcpy(&mp->base, &p->one->oid);
 162                         } else
 163                                 assert(!"Invalid existing change recorded");
 164                 } else {
 165                         oidcpy(&mp->obj, &obj);
 166                         oidcpy(&mp->base, &p->one->oid);
 167                         oidcpy(&mp->local, &uninitialized);
 168                         oidcpy(&mp->remote, &p->two->oid);
 169                         len++;
 170                 }
 171                 trace_printf("\t\tStored remote change for %s: %.7s -> %.7s\n",
 172                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
 173                        oid_to_hex(&mp->remote));
 174         }
 175         diff_flush(&opt);
 176         clear_pathspec(&opt.pathspec);
 177
 178         *num_changes = len;
 179         return changes;
 180 }
 181
 182 static void diff_tree_local(struct notes_merge_options *o,
 183                             struct notes_merge_pair *changes, int len,
 184                             const struct object_id *base,
 185                             const struct object_id *local)
 186 {
 187         struct diff_options opt;
 188         int i;
 189
 190         trace_printf("\tdiff_tree_local(len = %i, base = %.7s, local = %.7s)\n",
 191                len, oid_to_hex(base), oid_to_hex(local));
 192
 193         repo_diff_setup(the_repository, &opt);
 194         opt.flags.recursive = 1;
 195         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 196         diff_setup_done(&opt);
 197         diff_tree_oid(base, local, "", &opt);
 198         diffcore_std(&opt);
 199
 200         for (i = 0; i < diff_queued_diff.nr; i++) {
 201                 struct diff_filepair *p = diff_queued_diff.queue[i];
 202                 struct notes_merge_pair *mp;
 203                 int match;
 204                 struct object_id obj;
 205
 206                 if (verify_notes_filepair(p, &obj)) {
 207                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 208                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 209                                p->status, oid_to_hex(&p->one->oid),
 210                                oid_to_hex(&p->two->oid));
 211                         continue;
 212                 }
 213                 mp = find_notes_merge_pair_pos(changes, len, &obj, 0, &match);
 214                 if (!match) {
 215                         trace_printf("\t\tIgnoring local-only change for %s: "
 216                                "%.7s -> %.7s\n", oid_to_hex(&obj),
 217                                oid_to_hex(&p->one->oid),
 218                                oid_to_hex(&p->two->oid));
 219                         continue;
 220                 }
 221
 222                 assert(oideq(&mp->obj, &obj));
 223                 if (is_null_oid(&p->two->oid)) { /* deletion */
 224                         /*
 225                          * Either this is a true deletion (1), or it is part
 226                          * of an A/D pair (2), or D/A pair (3):
 227                          *
 228                          * (1) mp->local is uninitialized; set it to null_sha1
 229                          * (2) mp->local is not uninitialized; don't touch it
 230                          * (3) mp->local is uninitialized; set it to null_sha1
 231                          *     (will be overwritten by following addition)
 232                          */
 233                         if (oideq(&mp->local, &uninitialized))
 234                                 oidclr(&mp->local);
 235                 } else if (is_null_oid(&p->one->oid)) { /* addition */
 236                         /*
 237                          * Either this is a true addition (1), or it is part
 238                          * of an A/D pair (2), or D/A pair (3):
 239                          *
 240                          * (1) mp->local is uninitialized; set to p->two->sha1
 241                          * (2) mp->local is uninitialized; set to p->two->sha1
 242                          * (3) mp->local is null_sha1;     set to p->two->sha1
 243                          */
 244                         assert(is_null_oid(&mp->local) ||
 245                                oideq(&mp->local, &uninitialized));
 246                         oidcpy(&mp->local, &p->two->oid);
 247                 } else { /* modification */
 248                         /*
 249                          * This is a true modification. p->one->sha1 shall
 250                          * match mp->base, and mp->local shall be uninitialized.
 251                          * Set mp->local to p->two->sha1.
 252                          */
 253                         assert(oideq(&p->one->oid, &mp->base));
 254                         assert(oideq(&mp->local, &uninitialized));
 255                         oidcpy(&mp->local, &p->two->oid);
 256                 }
 257                 trace_printf("\t\tStored local change for %s: %.7s -> %.7s\n",
 258                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
 259                        oid_to_hex(&mp->local));
 260         }
 261         diff_flush(&opt);
 262         clear_pathspec(&opt.pathspec);
 263 }
 264
 265 static void check_notes_merge_worktree(struct notes_merge_options *o)
 266 {
 267         if (!o->has_worktree) {
 268                 /*
 269                  * Must establish NOTES_MERGE_WORKTREE.
 270                  * Abort if NOTES_MERGE_WORKTREE already exists
 271                  */
 272                 if (file_exists(git_path(NOTES_MERGE_WORKTREE)) &&
 273                     !is_empty_dir(git_path(NOTES_MERGE_WORKTREE))) {
 274                         if (advice_resolve_conflict)
 275                                 die(_("You have not concluded your previous "
 276                                     "notes merge (%s exists).\nPlease, use "
 277                                     "'git notes merge --commit' or 'git notes "
 278                                     "merge --abort' to commit/abort the "
 279                                     "previous merge before you start a new "
 280                                     "notes merge."), git_path("NOTES_MERGE_*"));
 281                         else
 282                                 die(_("You have not concluded your notes merge "
 283                                     "(%s exists)."), git_path("NOTES_MERGE_*"));
 284                 }
 285
 286                 if (safe_create_leading_directories_const(git_path(
 287                                 NOTES_MERGE_WORKTREE "/.test")))
 288                         die_errno("unable to create directory %s",
 289                                   git_path(NOTES_MERGE_WORKTREE));
 290                 o->has_worktree = 1;
 291         } else if (!file_exists(git_path(NOTES_MERGE_WORKTREE)))
 292                 /* NOTES_MERGE_WORKTREE should already be established */
 293                 die("missing '%s'. This should not happen",
 294                     git_path(NOTES_MERGE_WORKTREE));
 295 }
 296
 297 static void write_buf_to_worktree(const struct object_id *obj,
 298                                   const char *buf, unsigned long size)
 299 {
 300         int fd;
 301         char *path = git_pathdup(NOTES_MERGE_WORKTREE "/%s", oid_to_hex(obj));
 302         if (safe_create_leading_directories_const(path))
 303                 die_errno("unable to create directory for '%s'", path);
 304
 305         fd = xopen(path, O_WRONLY | O_EXCL | O_CREAT, 0666);
 306
 307         while (size > 0) {
 308                 ssize_t ret = write_in_full(fd, buf, size);
 309                 if (ret < 0) {
 310                         /* Ignore epipe */
 311                         if (errno == EPIPE)
 312                                 break;
 313                         die_errno("notes-merge");
 314                 }
 315                 size -= ret;
 316                 buf += ret;
 317         }
 318
 319         close(fd);
 320         free(path);
 321 }
 322
 323 static void write_note_to_worktree(const struct object_id *obj,
 324                                    const struct object_id *note)
 325 {
 326         enum object_type type;
 327         unsigned long size;
 328         void *buf = read_object_file(note, &type, &size);
 329
 330         if (!buf)
 331                 die("cannot read note %s for object %s",
 332                     oid_to_hex(note), oid_to_hex(obj));
 333         if (type != OBJ_BLOB)
 334                 die("blob expected in note %s for object %s",
 335                     oid_to_hex(note), oid_to_hex(obj));
 336         write_buf_to_worktree(obj, buf, size);
 337         free(buf);
 338 }
 339
 340 static int ll_merge_in_worktree(struct notes_merge_options *o,
 341                                 struct notes_merge_pair *p)
 342 {
 343         mmbuffer_t result_buf;
 344         mmfile_t base, local, remote;
 345         int status;
 346
 347         read_mmblob(&base, &p->base);
 348         read_mmblob(&local, &p->local);
 349         read_mmblob(&remote, &p->remote);
 350
 351         status = ll_merge(&result_buf, oid_to_hex(&p->obj), &base, NULL,
 352                           &local, o->local_ref, &remote, o->remote_ref,
 353                           &the_index, NULL);
 354
 355         free(base.ptr);
 356         free(local.ptr);
 357         free(remote.ptr);
 358
 359         if ((status < 0) || !result_buf.ptr)
 360                 die("Failed to execute internal merge");
 361
 362         write_buf_to_worktree(&p->obj, result_buf.ptr, result_buf.size);
 363         free(result_buf.ptr);
 364
 365         return status;
 366 }
 367
 368 static int merge_one_change_manual(struct notes_merge_options *o,
 369                                    struct notes_merge_pair *p,
 370                                    struct notes_tree *t)
 371 {
 372         const char *lref = o->local_ref ? o->local_ref : "local version";
 373         const char *rref = o->remote_ref ? o->remote_ref : "remote version";
 374
 375         trace_printf("\t\t\tmerge_one_change_manual(obj = %.7s, base = %.7s, "
 376                "local = %.7s, remote = %.7s)\n",
 377                oid_to_hex(&p->obj), oid_to_hex(&p->base),
 378                oid_to_hex(&p->local), oid_to_hex(&p->remote));
 379
 380         /* add "Conflicts:" section to commit message first time through */
 381         if (!o->has_worktree)
 382                 strbuf_addstr(&(o->commit_msg), "\n\nConflicts:\n");
 383
 384         strbuf_addf(&(o->commit_msg), "\t%s\n", oid_to_hex(&p->obj));
 385
 386         if (o->verbosity >= 2)
 387                 printf("Auto-merging notes for %s\n", oid_to_hex(&p->obj));
 388         check_notes_merge_worktree(o);
 389         if (is_null_oid(&p->local)) {
 390                 /* D/F conflict, checkout p->remote */
 391                 assert(!is_null_oid(&p->remote));
 392                 if (o->verbosity >= 1)
 393                         printf("CONFLICT (delete/modify): Notes for object %s "
 394                                 "deleted in %s and modified in %s. Version from %s "
 395                                 "left in tree.\n",
 396                                 oid_to_hex(&p->obj), lref, rref, rref);
 397                 write_note_to_worktree(&p->obj, &p->remote);
 398         } else if (is_null_oid(&p->remote)) {
 399                 /* D/F conflict, checkout p->local */
 400                 assert(!is_null_oid(&p->local));
 401                 if (o->verbosity >= 1)
 402                         printf("CONFLICT (delete/modify): Notes for object %s "
 403                                 "deleted in %s and modified in %s. Version from %s "
 404                                 "left in tree.\n",
 405                                 oid_to_hex(&p->obj), rref, lref, lref);
 406                 write_note_to_worktree(&p->obj, &p->local);
 407         } else {
 408                 /* "regular" conflict, checkout result of ll_merge() */
 409                 const char *reason = "content";
 410                 if (is_null_oid(&p->base))
 411                         reason = "add/add";
 412                 assert(!is_null_oid(&p->local));
 413                 assert(!is_null_oid(&p->remote));
 414                 if (o->verbosity >= 1)
 415                         printf("CONFLICT (%s): Merge conflict in notes for "
 416                                 "object %s\n", reason,
 417                                 oid_to_hex(&p->obj));
 418                 ll_merge_in_worktree(o, p);
 419         }
 420
 421         trace_printf("\t\t\tremoving from partial merge result\n");
 422         remove_note(t, p->obj.hash);
 423
 424         return 1;
 425 }
 426
 427 static int merge_one_change(struct notes_merge_options *o,
 428                             struct notes_merge_pair *p, struct notes_tree *t)
 429 {
 430         /*
 431          * Return 0 if change is successfully resolved (stored in notes_tree).
 432          * Return 1 is change results in a conflict (NOT stored in notes_tree,
 433          * but instead written to NOTES_MERGE_WORKTREE with conflict markers).
 434          */
 435         switch (o->strategy) {
 436         case NOTES_MERGE_RESOLVE_MANUAL:
 437                 return merge_one_change_manual(o, p, t);
 438         case NOTES_MERGE_RESOLVE_OURS:
 439                 if (o->verbosity >= 2)
 440                         printf("Using local notes for %s\n",
 441                                                 oid_to_hex(&p->obj));
 442                 /* nothing to do */
 443                 return 0;
 444         case NOTES_MERGE_RESOLVE_THEIRS:
 445                 if (o->verbosity >= 2)
 446                         printf("Using remote notes for %s\n",
 447                                                 oid_to_hex(&p->obj));
 448                 if (add_note(t, &p->obj, &p->remote, combine_notes_overwrite))
 449                         BUG("combine_notes_overwrite failed");
 450                 return 0;
 451         case NOTES_MERGE_RESOLVE_UNION:
 452                 if (o->verbosity >= 2)
 453                         printf("Concatenating local and remote notes for %s\n",
 454                                                         oid_to_hex(&p->obj));
 455                 if (add_note(t, &p->obj, &p->remote, combine_notes_concatenate))
 456                         die("failed to concatenate notes "
 457                             "(combine_notes_concatenate)");
 458                 return 0;
 459         case NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ:
 460                 if (o->verbosity >= 2)
 461                         printf("Concatenating unique lines in local and remote "
 462                                 "notes for %s\n", oid_to_hex(&p->obj));
 463                 if (add_note(t, &p->obj, &p->remote, combine_notes_cat_sort_uniq))
 464                         die("failed to concatenate notes "
 465                             "(combine_notes_cat_sort_uniq)");
 466                 return 0;
 467         }
 468         die("Unknown strategy (%i).", o->strategy);
 469 }
 470
 471 static int merge_changes(struct notes_merge_options *o,
 472                          struct notes_merge_pair *changes, int *num_changes,
 473                          struct notes_tree *t)
 474 {
 475         int i, conflicts = 0;
 476
 477         trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
 478         for (i = 0; i < *num_changes; i++) {
 479                 struct notes_merge_pair *p = changes + i;
 480                 trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
 481                        oid_to_hex(&p->obj), oid_to_hex(&p->base),
 482                        oid_to_hex(&p->local),
 483                        oid_to_hex(&p->remote));
 484
 485                 if (oideq(&p->base, &p->remote)) {
 486                         /* no remote change; nothing to do */
 487                         trace_printf("\t\t\tskipping (no remote change)\n");
 488                 } else if (oideq(&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 (oideq(&p->local, &uninitialized) ||
 492                            oideq(&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                                 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
 508 static int merge_from_diffs(struct notes_merge_options *o,
 509                             const struct object_id *base,
 510                             const struct object_id *local,
 511                             const struct object_id *remote,
 512                             struct notes_tree *t)
 513 {
 514         struct notes_merge_pair *changes;
 515         int num_changes, conflicts;
 516
 517         trace_printf("\tmerge_from_diffs(base = %.7s, local = %.7s, "
 518                "remote = %.7s)\n", oid_to_hex(base), oid_to_hex(local),
 519                oid_to_hex(remote));
 520
 521         changes = diff_tree_remote(o, base, remote, &num_changes);
 522         diff_tree_local(o, changes, num_changes, base, local);
 523
 524         conflicts = merge_changes(o, changes, &num_changes, t);
 525         free(changes);
 526
 527         if (o->verbosity >= 4)
 528                 printf(t->dirty ?
 529                        "Merge result: %i unmerged notes and a dirty notes tree\n" :
 530                        "Merge result: %i unmerged notes and a clean notes tree\n",
 531                        conflicts);
 532
 533         return conflicts ? -1 : 1;
 534 }
 535
 536 int notes_merge(struct notes_merge_options *o,
 537                 struct notes_tree *local_tree,
 538                 struct object_id *result_oid)
 539 {
 540         struct object_id local_oid, remote_oid;
 541         struct commit *local, *remote;
 542         struct commit_list *bases = NULL;
 543         const struct object_id *base_oid, *base_tree_oid;
 544         int result = 0;
 545
 546         assert(o->local_ref && o->remote_ref);
 547         assert(!strcmp(o->local_ref, local_tree->ref));
 548         oidclr(result_oid);
 549
 550         trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
 551                o->local_ref, o->remote_ref);
 552
 553         /* Dereference o->local_ref into local_sha1 */
 554         if (read_ref_full(o->local_ref, 0, &local_oid, NULL))
 555                 die("Failed to resolve local notes ref '%s'", o->local_ref);
 556         else if (!check_refname_format(o->local_ref, 0) &&
 557                 is_null_oid(&local_oid))
 558                 local = NULL; /* local_oid == null_oid indicates unborn ref */
 559         else if (!(local = lookup_commit_reference(the_repository, &local_oid)))
 560                 die("Could not parse local commit %s (%s)",
 561                     oid_to_hex(&local_oid), o->local_ref);
 562         trace_printf("\tlocal commit: %.7s\n", oid_to_hex(&local_oid));
 563
 564         /* Dereference o->remote_ref into remote_oid */
 565         if (get_oid(o->remote_ref, &remote_oid)) {
 566                 /*
 567                  * Failed to get remote_oid. If o->remote_ref looks like an
 568                  * unborn ref, perform the merge using an empty notes tree.
 569                  */
 570                 if (!check_refname_format(o->remote_ref, 0)) {
 571                         oidclr(&remote_oid);
 572                         remote = NULL;
 573                 } else {
 574                         die("Failed to resolve remote notes ref '%s'",
 575                             o->remote_ref);
 576                 }
 577         } else if (!(remote = lookup_commit_reference(the_repository, &remote_oid))) {
 578                 die("Could not parse remote commit %s (%s)",
 579                     oid_to_hex(&remote_oid), o->remote_ref);
 580         }
 581         trace_printf("\tremote commit: %.7s\n", oid_to_hex(&remote_oid));
 582
 583         if (!local && !remote)
 584                 die("Cannot merge empty notes ref (%s) into empty notes ref "
 585                     "(%s)", o->remote_ref, o->local_ref);
 586         if (!local) {
 587                 /* result == remote commit */
 588                 oidcpy(result_oid, &remote_oid);
 589                 goto found_result;
 590         }
 591         if (!remote) {
 592                 /* result == local commit */
 593                 oidcpy(result_oid, &local_oid);
 594                 goto found_result;
 595         }
 596         assert(local && remote);
 597
 598         /* Find merge bases */
 599         bases = get_merge_bases(local, remote);
 600         if (!bases) {
 601                 base_oid = &null_oid;
 602                 base_tree_oid = the_hash_algo->empty_tree;
 603                 if (o->verbosity >= 4)
 604                         printf("No merge base found; doing history-less merge\n");
 605         } else if (!bases->next) {
 606                 base_oid = &bases->item->object.oid;
 607                 base_tree_oid = get_commit_tree_oid(bases->item);
 608                 if (o->verbosity >= 4)
 609                         printf("One merge base found (%.7s)\n",
 610                                oid_to_hex(base_oid));
 611         } else {
 612                 /* TODO: How to handle multiple merge-bases? */
 613                 base_oid = &bases->item->object.oid;
 614                 base_tree_oid = get_commit_tree_oid(bases->item);
 615                 if (o->verbosity >= 3)
 616                         printf("Multiple merge bases found. Using the first "
 617                                 "(%.7s)\n", oid_to_hex(base_oid));
 618         }
 619
 620         if (o->verbosity >= 4)
 621                 printf("Merging remote commit %.7s into local commit %.7s with "
 622                         "merge-base %.7s\n", oid_to_hex(&remote->object.oid),
 623                         oid_to_hex(&local->object.oid),
 624                         oid_to_hex(base_oid));
 625
 626         if (oideq(&remote->object.oid, base_oid)) {
 627                 /* Already merged; result == local commit */
 628                 if (o->verbosity >= 2)
 629                         printf("Already up to date!\n");
 630                 oidcpy(result_oid, &local->object.oid);
 631                 goto found_result;
 632         }
 633         if (oideq(&local->object.oid, base_oid)) {
 634                 /* Fast-forward; result == remote commit */
 635                 if (o->verbosity >= 2)
 636                         printf("Fast-forward\n");
 637                 oidcpy(result_oid, &remote->object.oid);
 638                 goto found_result;
 639         }
 640
 641         result = merge_from_diffs(o, base_tree_oid,
 642                                   get_commit_tree_oid(local),
 643                                   get_commit_tree_oid(remote), local_tree);
 644
 645         if (result != 0) { /* non-trivial merge (with or without conflicts) */
 646                 /* Commit (partial) result */
 647                 struct commit_list *parents = NULL;
 648                 commit_list_insert(remote, &parents); /* LIFO order */
 649                 commit_list_insert(local, &parents);
 650                 create_notes_commit(local_tree, parents, o->commit_msg.buf,
 651                                     o->commit_msg.len, result_oid);
 652         }
 653
 654 found_result:
 655         free_commit_list(bases);
 656         strbuf_release(&(o->commit_msg));
 657         trace_printf("notes_merge(): result = %i, result_oid = %.7s\n",
 658                result, oid_to_hex(result_oid));
 659         return result;
 660 }
 661
 662 int notes_merge_commit(struct notes_merge_options *o,
 663                        struct notes_tree *partial_tree,
 664                        struct commit *partial_commit,
 665                        struct object_id *result_oid)
 666 {
 667         /*
 668          * Iterate through files in .git/NOTES_MERGE_WORKTREE and add all
 669          * found notes to 'partial_tree'. Write the updated notes tree to
 670          * the DB, and commit the resulting tree object while reusing the
 671          * commit message and parents from 'partial_commit'.
 672          * Finally store the new commit object OID into 'result_oid'.
 673          */
 674         DIR *dir;
 675         struct dirent *e;
 676         struct strbuf path = STRBUF_INIT;
 677         const char *buffer = get_commit_buffer(partial_commit, NULL);
 678         const char *msg = strstr(buffer, "\n\n");
 679         int baselen;
 680
 681         git_path_buf(&path, NOTES_MERGE_WORKTREE);
 682         if (o->verbosity >= 3)
 683                 printf("Committing notes in notes merge worktree at %s\n",
 684                         path.buf);
 685
 686         if (!msg || msg[2] == '\0')
 687                 die("partial notes commit has empty message");
 688         msg += 2;
 689
 690         dir = opendir(path.buf);
 691         if (!dir)
 692                 die_errno("could not open %s", path.buf);
 693
 694         strbuf_addch(&path, '/');
 695         baselen = path.len;
 696         while ((e = readdir(dir)) != NULL) {
 697                 struct stat st;
 698                 struct object_id obj_oid, blob_oid;
 699
 700                 if (is_dot_or_dotdot(e->d_name))
 701                         continue;
 702
 703                 if (get_oid_hex(e->d_name, &obj_oid)) {
 704                         if (o->verbosity >= 3)
 705                                 printf("Skipping non-SHA1 entry '%s%s'\n",
 706                                         path.buf, e->d_name);
 707                         continue;
 708                 }
 709
 710                 strbuf_addstr(&path, e->d_name);
 711                 /* write file as blob, and add to partial_tree */
 712                 if (stat(path.buf, &st))
 713                         die_errno("Failed to stat '%s'", path.buf);
 714                 if (index_path(&the_index, &blob_oid, path.buf, &st, HASH_WRITE_OBJECT))
 715                         die("Failed to write blob object from '%s'", path.buf);
 716                 if (add_note(partial_tree, &obj_oid, &blob_oid, NULL))
 717                         die("Failed to add resolved note '%s' to notes tree",
 718                             path.buf);
 719                 if (o->verbosity >= 4)
 720                         printf("Added resolved note for object %s: %s\n",
 721                                 oid_to_hex(&obj_oid), oid_to_hex(&blob_oid));
 722                 strbuf_setlen(&path, baselen);
 723         }
 724
 725         create_notes_commit(partial_tree, partial_commit->parents, msg,
 726                             strlen(msg), result_oid);
 727         unuse_commit_buffer(partial_commit, buffer);
 728         if (o->verbosity >= 4)
 729                 printf("Finalized notes merge commit: %s\n",
 730                         oid_to_hex(result_oid));
 731         strbuf_release(&path);
 732         closedir(dir);
 733         return 0;
 734 }
 735
 736 int notes_merge_abort(struct notes_merge_options *o)
 737 {
 738         /*
 739          * Remove all files within .git/NOTES_MERGE_WORKTREE. We do not remove
 740          * the .git/NOTES_MERGE_WORKTREE directory itself, since it might be
 741          * the current working directory of the user.
 742          */
 743         struct strbuf buf = STRBUF_INIT;
 744         int ret;
 745
 746         git_path_buf(&buf, NOTES_MERGE_WORKTREE);
 747         if (o->verbosity >= 3)
 748                 printf("Removing notes merge worktree at %s/*\n", buf.buf);
 749         ret = remove_dir_recursively(&buf, REMOVE_DIR_KEEP_TOPLEVEL);
 750         strbuf_release(&buf);
 751         return ret;
 752 }