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 repository *r,
  22                               struct notes_merge_options *o)
  23 {
  24         memset(o, 0, sizeof(struct notes_merge_options));
  25         strbuf_init(&(o->commit_msg), 0);
  26         o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
  27         o->repo = r;
  28 }
  29
  30 static int path_to_oid(const char *path, struct object_id *oid)
  31 {
  32         char hex_oid[GIT_MAX_HEXSZ];
  33         int i = 0;
  34         while (*path && i < the_hash_algo->hexsz) {
  35                 if (*path != '/')
  36                         hex_oid[i++] = *path;
  37                 path++;
  38         }
  39         if (*path || i != the_hash_algo->hexsz)
  40                 return -1;
  41         return get_oid_hex(hex_oid, oid);
  42 }
  43
  44 static int verify_notes_filepair(struct diff_filepair *p, struct object_id *oid)
  45 {
  46         switch (p->status) {
  47         case DIFF_STATUS_MODIFIED:
  48                 assert(p->one->mode == p->two->mode);
  49                 assert(!is_null_oid(&p->one->oid));
  50                 assert(!is_null_oid(&p->two->oid));
  51                 break;
  52         case DIFF_STATUS_ADDED:
  53                 assert(is_null_oid(&p->one->oid));
  54                 break;
  55         case DIFF_STATUS_DELETED:
  56                 assert(is_null_oid(&p->two->oid));
  57                 break;
  58         default:
  59                 return -1;
  60         }
  61         assert(!strcmp(p->one->path, p->two->path));
  62         return path_to_oid(p->one->path, oid);
  63 }
  64
  65 static struct notes_merge_pair *find_notes_merge_pair_pos(
  66                 struct notes_merge_pair *list, int len, struct object_id *obj,
  67                 int insert_new, int *occupied)
  68 {
  69         /*
  70          * Both diff_tree_remote() and diff_tree_local() tend to process
  71          * merge_pairs in ascending order. Therefore, cache last returned
  72          * index, and search sequentially from there until the appropriate
  73          * position is found.
  74          *
  75          * Since inserts only happen from diff_tree_remote() (which mainly
  76          * _appends_), we don't care that inserting into the middle of the
  77          * list is expensive (using memmove()).
  78          */
  79         static int last_index;
  80         int i = last_index < len ? last_index : len - 1;
  81         int prev_cmp = 0, cmp = -1;
  82         while (i >= 0 && i < len) {
  83                 cmp = oidcmp(obj, &list[i].obj);
  84                 if (!cmp) /* obj belongs @ i */
  85                         break;
  86                 else if (cmp < 0 && prev_cmp <= 0) /* obj belongs < i */
  87                         i--;
  88                 else if (cmp < 0) /* obj belongs between i-1 and i */
  89                         break;
  90                 else if (cmp > 0 && prev_cmp >= 0) /* obj belongs > i */
  91                         i++;
  92                 else /* if (cmp > 0) */ { /* obj belongs between i and i+1 */
  93                         i++;
  94                         break;
  95                 }
  96                 prev_cmp = cmp;
  97         }
  98         if (i < 0)
  99                 i = 0;
 100         /* obj belongs at, or immediately preceding, index i (0 <= i <= len) */
 101
 102         if (!cmp)
 103                 *occupied = 1;
 104         else {
 105                 *occupied = 0;
 106                 if (insert_new && i < len) {
 107                         MOVE_ARRAY(list + i + 1, list + i, len - i);
 108                         memset(list + i, 0, sizeof(struct notes_merge_pair));
 109                 }
 110         }
 111         last_index = i;
 112         return list + i;
 113 }
 114
 115 static struct object_id uninitialized = {
 116         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" \
 117         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
 118 };
 119
 120 static struct notes_merge_pair *diff_tree_remote(struct notes_merge_options *o,
 121                                                  const struct object_id *base,
 122                                                  const struct object_id *remote,
 123                                                  int *num_changes)
 124 {
 125         struct diff_options opt;
 126         struct notes_merge_pair *changes;
 127         int i, len = 0;
 128
 129         trace_printf("\tdiff_tree_remote(base = %.7s, remote = %.7s)\n",
 130                oid_to_hex(base), oid_to_hex(remote));
 131
 132         repo_diff_setup(o->repo, &opt);
 133         opt.flags.recursive = 1;
 134         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 135         diff_setup_done(&opt);
 136         diff_tree_oid(base, remote, "", &opt);
 137         diffcore_std(&opt);
 138
 139         CALLOC_ARRAY(changes, diff_queued_diff.nr);
 140
 141         for (i = 0; i < diff_queued_diff.nr; i++) {
 142                 struct diff_filepair *p = diff_queued_diff.queue[i];
 143                 struct notes_merge_pair *mp;
 144                 int occupied;
 145                 struct object_id obj;
 146
 147                 if (verify_notes_filepair(p, &obj)) {
 148                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 149                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 150                                p->status, oid_to_hex(&p->one->oid),
 151                                oid_to_hex(&p->two->oid));
 152                         continue;
 153                 }
 154                 mp = find_notes_merge_pair_pos(changes, len, &obj, 1, &occupied);
 155                 if (occupied) {
 156                         /* We've found an addition/deletion pair */
 157                         assert(oideq(&mp->obj, &obj));
 158                         if (is_null_oid(&p->one->oid)) { /* addition */
 159                                 assert(is_null_oid(&mp->remote));
 160                                 oidcpy(&mp->remote, &p->two->oid);
 161                         } else if (is_null_oid(&p->two->oid)) { /* deletion */
 162                                 assert(is_null_oid(&mp->base));
 163                                 oidcpy(&mp->base, &p->one->oid);
 164                         } else
 165                                 assert(!"Invalid existing change recorded");
 166                 } else {
 167                         oidcpy(&mp->obj, &obj);
 168                         oidcpy(&mp->base, &p->one->oid);
 169                         oidcpy(&mp->local, &uninitialized);
 170                         oidcpy(&mp->remote, &p->two->oid);
 171                         len++;
 172                 }
 173                 trace_printf("\t\tStored remote change for %s: %.7s -> %.7s\n",
 174                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
 175                        oid_to_hex(&mp->remote));
 176         }
 177         diff_flush(&opt);
 178
 179         *num_changes = len;
 180         return changes;
 181 }
 182
 183 static void diff_tree_local(struct notes_merge_options *o,
 184                             struct notes_merge_pair *changes, int len,
 185                             const struct object_id *base,
 186                             const struct object_id *local)
 187 {
 188         struct diff_options opt;
 189         int i;
 190
 191         trace_printf("\tdiff_tree_local(len = %i, base = %.7s, local = %.7s)\n",
 192                len, oid_to_hex(base), oid_to_hex(local));
 193
 194         repo_diff_setup(o->repo, &opt);
 195         opt.flags.recursive = 1;
 196         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 197         diff_setup_done(&opt);
 198         diff_tree_oid(base, local, "", &opt);
 199         diffcore_std(&opt);
 200
 201         for (i = 0; i < diff_queued_diff.nr; i++) {
 202                 struct diff_filepair *p = diff_queued_diff.queue[i];
 203                 struct notes_merge_pair *mp;
 204                 int match;
 205                 struct object_id obj;
 206
 207                 if (verify_notes_filepair(p, &obj)) {
 208                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 209                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 210                                p->status, oid_to_hex(&p->one->oid),
 211                                oid_to_hex(&p->two->oid));
 212                         continue;
 213                 }
 214                 mp = find_notes_merge_pair_pos(changes, len, &obj, 0, &match);
 215                 if (!match) {
 216                         trace_printf("\t\tIgnoring local-only change for %s: "
 217                                "%.7s -> %.7s\n", oid_to_hex(&obj),
 218                                oid_to_hex(&p->one->oid),
 219                                oid_to_hex(&p->two->oid));
 220                         continue;
 221                 }
 222
 223                 assert(oideq(&mp->obj, &obj));
 224                 if (is_null_oid(&p->two->oid)) { /* deletion */
 225                         /*
 226                          * Either this is a true deletion (1), or it is part
 227                          * of an A/D pair (2), or D/A pair (3):
 228                          *
 229                          * (1) mp->local is uninitialized; set it to null_sha1
 230                          * (2) mp->local is not uninitialized; don't touch it
 231                          * (3) mp->local is uninitialized; set it to null_sha1
 232                          *     (will be overwritten by following addition)
 233                          */
 234                         if (oideq(&mp->local, &uninitialized))
 235                                 oidclr(&mp->local);
 236                 } else if (is_null_oid(&p->one->oid)) { /* addition */
 237                         /*
 238                          * Either this is a true addition (1), or it is part
 239                          * of an A/D pair (2), or D/A pair (3):
 240                          *
 241                          * (1) mp->local is uninitialized; set to p->two->sha1
 242                          * (2) mp->local is uninitialized; set to p->two->sha1
 243                          * (3) mp->local is null_sha1;     set to p->two->sha1
 244                          */
 245                         assert(is_null_oid(&mp->local) ||
 246                                oideq(&mp->local, &uninitialized));
 247                         oidcpy(&mp->local, &p->two->oid);
 248                 } else { /* modification */
 249                         /*
 250                          * This is a true modification. p->one->sha1 shall
 251                          * match mp->base, and mp->local shall be uninitialized.
 252                          * Set mp->local to p->two->sha1.
 253                          */
 254                         assert(oideq(&p->one->oid, &mp->base));
 255                         assert(oideq(&mp->local, &uninitialized));
 256                         oidcpy(&mp->local, &p->two->oid);
 257                 }
 258                 trace_printf("\t\tStored local change for %s: %.7s -> %.7s\n",
 259                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
 260                        oid_to_hex(&mp->local));
 261         }
 262         diff_flush(&opt);
 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_enabled(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         enum ll_merge_result 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                           o->repo->index, NULL);
 354
 355         free(base.ptr);
 356         free(local.ptr);
 357         free(remote.ptr);
 358
 359         if (status == LL_MERGE_BINARY_CONFLICT)
 360                 warning("Cannot merge binary files: %s (%s vs. %s)",
 361                         oid_to_hex(&p->obj), o->local_ref, o->remote_ref);
 362         if ((status < 0) || !result_buf.ptr)
 363                 die("Failed to execute internal merge");
 364
 365         write_buf_to_worktree(&p->obj, result_buf.ptr, result_buf.size);
 366         free(result_buf.ptr);
 367
 368         return status;
 369 }
 370
 371 static int merge_one_change_manual(struct notes_merge_options *o,
 372                                    struct notes_merge_pair *p,
 373                                    struct notes_tree *t)
 374 {
 375         const char *lref = o->local_ref ? o->local_ref : "local version";
 376         const char *rref = o->remote_ref ? o->remote_ref : "remote version";
 377
 378         trace_printf("\t\t\tmerge_one_change_manual(obj = %.7s, base = %.7s, "
 379                "local = %.7s, remote = %.7s)\n",
 380                oid_to_hex(&p->obj), oid_to_hex(&p->base),
 381                oid_to_hex(&p->local), oid_to_hex(&p->remote));
 382
 383         /* add "Conflicts:" section to commit message first time through */
 384         if (!o->has_worktree)
 385                 strbuf_addstr(&(o->commit_msg), "\n\nConflicts:\n");
 386
 387         strbuf_addf(&(o->commit_msg), "\t%s\n", oid_to_hex(&p->obj));
 388
 389         if (o->verbosity >= 2)
 390                 printf("Auto-merging notes for %s\n", oid_to_hex(&p->obj));
 391         check_notes_merge_worktree(o);
 392         if (is_null_oid(&p->local)) {
 393                 /* D/F conflict, checkout p->remote */
 394                 assert(!is_null_oid(&p->remote));
 395                 if (o->verbosity >= 1)
 396                         printf("CONFLICT (delete/modify): Notes for object %s "
 397                                 "deleted in %s and modified in %s. Version from %s "
 398                                 "left in tree.\n",
 399                                 oid_to_hex(&p->obj), lref, rref, rref);
 400                 write_note_to_worktree(&p->obj, &p->remote);
 401         } else if (is_null_oid(&p->remote)) {
 402                 /* D/F conflict, checkout p->local */
 403                 assert(!is_null_oid(&p->local));
 404                 if (o->verbosity >= 1)
 405                         printf("CONFLICT (delete/modify): Notes for object %s "
 406                                 "deleted in %s and modified in %s. Version from %s "
 407                                 "left in tree.\n",
 408                                 oid_to_hex(&p->obj), rref, lref, lref);
 409                 write_note_to_worktree(&p->obj, &p->local);
 410         } else {
 411                 /* "regular" conflict, checkout result of ll_merge() */
 412                 const char *reason = "content";
 413                 if (is_null_oid(&p->base))
 414                         reason = "add/add";
 415                 assert(!is_null_oid(&p->local));
 416                 assert(!is_null_oid(&p->remote));
 417                 if (o->verbosity >= 1)
 418                         printf("CONFLICT (%s): Merge conflict in notes for "
 419                                 "object %s\n", reason,
 420                                 oid_to_hex(&p->obj));
 421                 ll_merge_in_worktree(o, p);
 422         }
 423
 424         trace_printf("\t\t\tremoving from partial merge result\n");
 425         remove_note(t, p->obj.hash);
 426
 427         return 1;
 428 }
 429
 430 static int merge_one_change(struct notes_merge_options *o,
 431                             struct notes_merge_pair *p, struct notes_tree *t)
 432 {
 433         /*
 434          * Return 0 if change is successfully resolved (stored in notes_tree).
 435          * Return 1 is change results in a conflict (NOT stored in notes_tree,
 436          * but instead written to NOTES_MERGE_WORKTREE with conflict markers).
 437          */
 438         switch (o->strategy) {
 439         case NOTES_MERGE_RESOLVE_MANUAL:
 440                 return merge_one_change_manual(o, p, t);
 441         case NOTES_MERGE_RESOLVE_OURS:
 442                 if (o->verbosity >= 2)
 443                         printf("Using local notes for %s\n",
 444                                                 oid_to_hex(&p->obj));
 445                 /* nothing to do */
 446                 return 0;
 447         case NOTES_MERGE_RESOLVE_THEIRS:
 448                 if (o->verbosity >= 2)
 449                         printf("Using remote notes for %s\n",
 450                                                 oid_to_hex(&p->obj));
 451                 if (add_note(t, &p->obj, &p->remote, combine_notes_overwrite))
 452                         BUG("combine_notes_overwrite failed");
 453                 return 0;
 454         case NOTES_MERGE_RESOLVE_UNION:
 455                 if (o->verbosity >= 2)
 456                         printf("Concatenating local and remote notes for %s\n",
 457                                                         oid_to_hex(&p->obj));
 458                 if (add_note(t, &p->obj, &p->remote, combine_notes_concatenate))
 459                         die("failed to concatenate notes "
 460                             "(combine_notes_concatenate)");
 461                 return 0;
 462         case NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ:
 463                 if (o->verbosity >= 2)
 464                         printf("Concatenating unique lines in local and remote "
 465                                 "notes for %s\n", oid_to_hex(&p->obj));
 466                 if (add_note(t, &p->obj, &p->remote, combine_notes_cat_sort_uniq))
 467                         die("failed to concatenate notes "
 468                             "(combine_notes_cat_sort_uniq)");
 469                 return 0;
 470         }
 471         die("Unknown strategy (%i).", o->strategy);
 472 }
 473
 474 static int merge_changes(struct notes_merge_options *o,
 475                          struct notes_merge_pair *changes, int *num_changes,
 476                          struct notes_tree *t)
 477 {
 478         int i, conflicts = 0;
 479
 480         trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
 481         for (i = 0; i < *num_changes; i++) {
 482                 struct notes_merge_pair *p = changes + i;
 483                 trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
 484                        oid_to_hex(&p->obj), oid_to_hex(&p->base),
 485                        oid_to_hex(&p->local),
 486                        oid_to_hex(&p->remote));
 487
 488                 if (oideq(&p->base, &p->remote)) {
 489                         /* no remote change; nothing to do */
 490                         trace_printf("\t\t\tskipping (no remote change)\n");
 491                 } else if (oideq(&p->local, &p->remote)) {
 492                         /* same change in local and remote; nothing to do */
 493                         trace_printf("\t\t\tskipping (local == remote)\n");
 494                 } else if (oideq(&p->local, &uninitialized) ||
 495                            oideq(&p->local, &p->base)) {
 496                         /* no local change; adopt remote change */
 497                         trace_printf("\t\t\tno local change, adopted remote\n");
 498                         if (add_note(t, &p->obj, &p->remote,
 499                                      combine_notes_overwrite))
 500                                 BUG("combine_notes_overwrite failed");
 501                 } else {
 502                         /* need file-level merge between local and remote */
 503                         trace_printf("\t\t\tneed content-level merge\n");
 504                         conflicts += merge_one_change(o, p, t);
 505                 }
 506         }
 507
 508         return conflicts;
 509 }
 510
 511 static int merge_from_diffs(struct notes_merge_options *o,
 512                             const struct object_id *base,
 513                             const struct object_id *local,
 514                             const struct object_id *remote,
 515                             struct notes_tree *t)
 516 {
 517         struct notes_merge_pair *changes;
 518         int num_changes, conflicts;
 519
 520         trace_printf("\tmerge_from_diffs(base = %.7s, local = %.7s, "
 521                "remote = %.7s)\n", oid_to_hex(base), oid_to_hex(local),
 522                oid_to_hex(remote));
 523
 524         changes = diff_tree_remote(o, base, remote, &num_changes);
 525         diff_tree_local(o, changes, num_changes, base, local);
 526
 527         conflicts = merge_changes(o, changes, &num_changes, t);
 528         free(changes);
 529
 530         if (o->verbosity >= 4)
 531                 printf(t->dirty ?
 532                        "Merge result: %i unmerged notes and a dirty notes tree\n" :
 533                        "Merge result: %i unmerged notes and a clean notes tree\n",
 534                        conflicts);
 535
 536         return conflicts ? -1 : 1;
 537 }
 538
 539 int notes_merge(struct notes_merge_options *o,
 540                 struct notes_tree *local_tree,
 541                 struct object_id *result_oid)
 542 {
 543         struct object_id local_oid, remote_oid;
 544         struct commit *local, *remote;
 545         struct commit_list *bases = NULL;
 546         const struct object_id *base_oid, *base_tree_oid;
 547         int result = 0;
 548
 549         assert(o->local_ref && o->remote_ref);
 550         assert(!strcmp(o->local_ref, local_tree->ref));
 551         oidclr(result_oid);
 552
 553         trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
 554                o->local_ref, o->remote_ref);
 555
 556         /* Dereference o->local_ref into local_sha1 */
 557         if (read_ref_full(o->local_ref, 0, &local_oid, NULL))
 558                 die("Failed to resolve local notes ref '%s'", o->local_ref);
 559         else if (!check_refname_format(o->local_ref, 0) &&
 560                 is_null_oid(&local_oid))
 561                 local = NULL; /* local_oid == null_oid indicates unborn ref */
 562         else if (!(local = lookup_commit_reference(o->repo, &local_oid)))
 563                 die("Could not parse local commit %s (%s)",
 564                     oid_to_hex(&local_oid), o->local_ref);
 565         trace_printf("\tlocal commit: %.7s\n", oid_to_hex(&local_oid));
 566
 567         /* Dereference o->remote_ref into remote_oid */
 568         if (get_oid(o->remote_ref, &remote_oid)) {
 569                 /*
 570                  * Failed to get remote_oid. If o->remote_ref looks like an
 571                  * unborn ref, perform the merge using an empty notes tree.
 572                  */
 573                 if (!check_refname_format(o->remote_ref, 0)) {
 574                         oidclr(&remote_oid);
 575                         remote = NULL;
 576                 } else {
 577                         die("Failed to resolve remote notes ref '%s'",
 578                             o->remote_ref);
 579                 }
 580         } else if (!(remote = lookup_commit_reference(o->repo, &remote_oid))) {
 581                 die("Could not parse remote commit %s (%s)",
 582                     oid_to_hex(&remote_oid), o->remote_ref);
 583         }
 584         trace_printf("\tremote commit: %.7s\n", oid_to_hex(&remote_oid));
 585
 586         if (!local && !remote)
 587                 die("Cannot merge empty notes ref (%s) into empty notes ref "
 588                     "(%s)", o->remote_ref, o->local_ref);
 589         if (!local) {
 590                 /* result == remote commit */
 591                 oidcpy(result_oid, &remote_oid);
 592                 goto found_result;
 593         }
 594         if (!remote) {
 595                 /* result == local commit */
 596                 oidcpy(result_oid, &local_oid);
 597                 goto found_result;
 598         }
 599         assert(local && remote);
 600
 601         /* Find merge bases */
 602         bases = get_merge_bases(local, remote);
 603         if (!bases) {
 604                 base_oid = null_oid();
 605                 base_tree_oid = the_hash_algo->empty_tree;
 606                 if (o->verbosity >= 4)
 607                         printf("No merge base found; doing history-less merge\n");
 608         } else if (!bases->next) {
 609                 base_oid = &bases->item->object.oid;
 610                 base_tree_oid = get_commit_tree_oid(bases->item);
 611                 if (o->verbosity >= 4)
 612                         printf("One merge base found (%.7s)\n",
 613                                oid_to_hex(base_oid));
 614         } else {
 615                 /* TODO: How to handle multiple merge-bases? */
 616                 base_oid = &bases->item->object.oid;
 617                 base_tree_oid = get_commit_tree_oid(bases->item);
 618                 if (o->verbosity >= 3)
 619                         printf("Multiple merge bases found. Using the first "
 620                                 "(%.7s)\n", oid_to_hex(base_oid));
 621         }
 622
 623         if (o->verbosity >= 4)
 624                 printf("Merging remote commit %.7s into local commit %.7s with "
 625                         "merge-base %.7s\n", oid_to_hex(&remote->object.oid),
 626                         oid_to_hex(&local->object.oid),
 627                         oid_to_hex(base_oid));
 628
 629         if (oideq(&remote->object.oid, base_oid)) {
 630                 /* Already merged; result == local commit */
 631                 if (o->verbosity >= 2)
 632                         printf_ln("Already up to date.");
 633                 oidcpy(result_oid, &local->object.oid);
 634                 goto found_result;
 635         }
 636         if (oideq(&local->object.oid, base_oid)) {
 637                 /* Fast-forward; result == remote commit */
 638                 if (o->verbosity >= 2)
 639                         printf("Fast-forward\n");
 640                 oidcpy(result_oid, &remote->object.oid);
 641                 goto found_result;
 642         }
 643
 644         result = merge_from_diffs(o, base_tree_oid,
 645                                   get_commit_tree_oid(local),
 646                                   get_commit_tree_oid(remote), local_tree);
 647
 648         if (result != 0) { /* non-trivial merge (with or without conflicts) */
 649                 /* Commit (partial) result */
 650                 struct commit_list *parents = NULL;
 651                 commit_list_insert(remote, &parents); /* LIFO order */
 652                 commit_list_insert(local, &parents);
 653                 create_notes_commit(o->repo, local_tree, parents, o->commit_msg.buf,
 654                                     o->commit_msg.len, result_oid);
 655         }
 656
 657 found_result:
 658         free_commit_list(bases);
 659         strbuf_release(&(o->commit_msg));
 660         trace_printf("notes_merge(): result = %i, result_oid = %.7s\n",
 661                result, oid_to_hex(result_oid));
 662         return result;
 663 }
 664
 665 int notes_merge_commit(struct notes_merge_options *o,
 666                        struct notes_tree *partial_tree,
 667                        struct commit *partial_commit,
 668                        struct object_id *result_oid)
 669 {
 670         /*
 671          * Iterate through files in .git/NOTES_MERGE_WORKTREE and add all
 672          * found notes to 'partial_tree'. Write the updated notes tree to
 673          * the DB, and commit the resulting tree object while reusing the
 674          * commit message and parents from 'partial_commit'.
 675          * Finally store the new commit object OID into 'result_oid'.
 676          */
 677         DIR *dir;
 678         struct dirent *e;
 679         struct strbuf path = STRBUF_INIT;
 680         const char *buffer = get_commit_buffer(partial_commit, NULL);
 681         const char *msg = strstr(buffer, "\n\n");
 682         int baselen;
 683
 684         git_path_buf(&path, NOTES_MERGE_WORKTREE);
 685         if (o->verbosity >= 3)
 686                 printf("Committing notes in notes merge worktree at %s\n",
 687                         path.buf);
 688
 689         if (!msg || msg[2] == '\0')
 690                 die("partial notes commit has empty message");
 691         msg += 2;
 692
 693         dir = opendir(path.buf);
 694         if (!dir)
 695                 die_errno("could not open %s", path.buf);
 696
 697         strbuf_addch(&path, '/');
 698         baselen = path.len;
 699         while ((e = readdir_skip_dot_and_dotdot(dir)) != NULL) {
 700                 struct stat st;
 701                 struct object_id obj_oid, blob_oid;
 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(o->repo->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(o->repo, 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 }