notes-merge.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "gettext.h"
   4 #include "refs.h"
   5 #include "object-store.h"
   6 #include "repository.h"
   7 #include "diff.h"
   8 #include "diffcore.h"
   9 #include "hex.h"
  10 #include "xdiff-interface.h"
  11 #include "ll-merge.h"
  12 #include "dir.h"
  13 #include "notes.h"
  14 #include "notes-merge.h"
  15 #include "strbuf.h"
  16 #include "notes-utils.h"
  17 #include "commit-reach.h"
  18
  19 struct notes_merge_pair {
  20         struct object_id obj, base, local, remote;
  21 };
  22
  23 void init_notes_merge_options(struct repository *r,
  24                               struct notes_merge_options *o)
  25 {
  26         memset(o, 0, sizeof(struct notes_merge_options));
  27         strbuf_init(&(o->commit_msg), 0);
  28         o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
  29         o->repo = r;
  30 }
  31
  32 static int path_to_oid(const char *path, struct object_id *oid)
  33 {
  34         char hex_oid[GIT_MAX_HEXSZ];
  35         int i = 0;
  36         while (*path && i < the_hash_algo->hexsz) {
  37                 if (*path != '/')
  38                         hex_oid[i++] = *path;
  39                 path++;
  40         }
  41         if (*path || i != the_hash_algo->hexsz)
  42                 return -1;
  43         return get_oid_hex(hex_oid, oid);
  44 }
  45
  46 static int verify_notes_filepair(struct diff_filepair *p, struct object_id *oid)
  47 {
  48         switch (p->status) {
  49         case DIFF_STATUS_MODIFIED:
  50                 assert(p->one->mode == p->two->mode);
  51                 assert(!is_null_oid(&p->one->oid));
  52                 assert(!is_null_oid(&p->two->oid));
  53                 break;
  54         case DIFF_STATUS_ADDED:
  55                 assert(is_null_oid(&p->one->oid));
  56                 break;
  57         case DIFF_STATUS_DELETED:
  58                 assert(is_null_oid(&p->two->oid));
  59                 break;
  60         default:
  61                 return -1;
  62         }
  63         assert(!strcmp(p->one->path, p->two->path));
  64         return path_to_oid(p->one->path, oid);
  65 }
  66
  67 static struct notes_merge_pair *find_notes_merge_pair_pos(
  68                 struct notes_merge_pair *list, int len, struct object_id *obj,
  69                 int insert_new, int *occupied)
  70 {
  71         /*
  72          * Both diff_tree_remote() and diff_tree_local() tend to process
  73          * merge_pairs in ascending order. Therefore, cache last returned
  74          * index, and search sequentially from there until the appropriate
  75          * position is found.
  76          *
  77          * Since inserts only happen from diff_tree_remote() (which mainly
  78          * _appends_), we don't care that inserting into the middle of the
  79          * list is expensive (using memmove()).
  80          */
  81         static int last_index;
  82         int i = last_index < len ? last_index : len - 1;
  83         int prev_cmp = 0, cmp = -1;
  84         while (i >= 0 && i < len) {
  85                 cmp = oidcmp(obj, &list[i].obj);
  86                 if (!cmp) /* obj belongs @ 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-1 and i */
  91                         break;
  92                 else if (cmp > 0 && prev_cmp >= 0) /* obj belongs > i */
  93                         i++;
  94                 else /* if (cmp > 0) */ { /* obj belongs between i and i+1 */
  95                         i++;
  96                         break;
  97                 }
  98                 prev_cmp = cmp;
  99         }
 100         if (i < 0)
 101                 i = 0;
 102         /* obj belongs at, or immediately preceding, index i (0 <= i <= len) */
 103
 104         if (!cmp)
 105                 *occupied = 1;
 106         else {
 107                 *occupied = 0;
 108                 if (insert_new && i < len) {
 109                         MOVE_ARRAY(list + i + 1, list + i, len - i);
 110                         memset(list + i, 0, sizeof(struct notes_merge_pair));
 111                 }
 112         }
 113         last_index = i;
 114         return list + i;
 115 }
 116
 117 static struct object_id uninitialized = {
 118         .hash =
 119         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" \
 120         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
 121 };
 122
 123 static struct notes_merge_pair *diff_tree_remote(struct notes_merge_options *o,
 124                                                  const struct object_id *base,
 125                                                  const struct object_id *remote,
 126                                                  int *num_changes)
 127 {
 128         struct diff_options opt;
 129         struct notes_merge_pair *changes;
 130         int i, len = 0;
 131
 132         trace_printf("\tdiff_tree_remote(base = %.7s, remote = %.7s)\n",
 133                oid_to_hex(base), oid_to_hex(remote));
 134
 135         repo_diff_setup(o->repo, &opt);
 136         opt.flags.recursive = 1;
 137         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 138         diff_setup_done(&opt);
 139         diff_tree_oid(base, remote, "", &opt);
 140         diffcore_std(&opt);
 141
 142         CALLOC_ARRAY(changes, diff_queued_diff.nr);
 143
 144         for (i = 0; i < diff_queued_diff.nr; i++) {
 145                 struct diff_filepair *p = diff_queued_diff.queue[i];
 146                 struct notes_merge_pair *mp;
 147                 int occupied;
 148                 struct object_id obj;
 149
 150                 if (verify_notes_filepair(p, &obj)) {
 151                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 152                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 153                                p->status, oid_to_hex(&p->one->oid),
 154                                oid_to_hex(&p->two->oid));
 155                         continue;
 156                 }
 157                 mp = find_notes_merge_pair_pos(changes, len, &obj, 1, &occupied);
 158                 if (occupied) {
 159                         /* We've found an addition/deletion pair */
 160                         assert(oideq(&mp->obj, &obj));
 161                         if (is_null_oid(&p->one->oid)) { /* addition */
 162                                 assert(is_null_oid(&mp->remote));
 163                                 oidcpy(&mp->remote, &p->two->oid);
 164                         } else if (is_null_oid(&p->two->oid)) { /* deletion */
 165                                 assert(is_null_oid(&mp->base));
 166                                 oidcpy(&mp->base, &p->one->oid);
 167                         } else
 168                                 assert(!"Invalid existing change recorded");
 169                 } else {
 170                         oidcpy(&mp->obj, &obj);
 171                         oidcpy(&mp->base, &p->one->oid);
 172                         oidcpy(&mp->local, &uninitialized);
 173                         oidcpy(&mp->remote, &p->two->oid);
 174                         len++;
 175                 }
 176                 trace_printf("\t\tStored remote change for %s: %.7s -> %.7s\n",
 177                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
 178                        oid_to_hex(&mp->remote));
 179         }
 180         diff_flush(&opt);
 181
 182         *num_changes = len;
 183         return changes;
 184 }
 185
 186 static void diff_tree_local(struct notes_merge_options *o,
 187                             struct notes_merge_pair *changes, int len,
 188                             const struct object_id *base,
 189                             const struct object_id *local)
 190 {
 191         struct diff_options opt;
 192         int i;
 193
 194         trace_printf("\tdiff_tree_local(len = %i, base = %.7s, local = %.7s)\n",
 195                len, oid_to_hex(base), oid_to_hex(local));
 196
 197         repo_diff_setup(o->repo, &opt);
 198         opt.flags.recursive = 1;
 199         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 200         diff_setup_done(&opt);
 201         diff_tree_oid(base, local, "", &opt);
 202         diffcore_std(&opt);
 203
 204         for (i = 0; i < diff_queued_diff.nr; i++) {
 205                 struct diff_filepair *p = diff_queued_diff.queue[i];
 206                 struct notes_merge_pair *mp;
 207                 int match;
 208                 struct object_id obj;
 209
 210                 if (verify_notes_filepair(p, &obj)) {
 211                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 212                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 213                                p->status, oid_to_hex(&p->one->oid),
 214                                oid_to_hex(&p->two->oid));
 215                         continue;
 216                 }
 217                 mp = find_notes_merge_pair_pos(changes, len, &obj, 0, &match);
 218                 if (!match) {
 219                         trace_printf("\t\tIgnoring local-only change for %s: "
 220                                "%.7s -> %.7s\n", oid_to_hex(&obj),
 221                                oid_to_hex(&p->one->oid),
 222                                oid_to_hex(&p->two->oid));
 223                         continue;
 224                 }
 225
 226                 assert(oideq(&mp->obj, &obj));
 227                 if (is_null_oid(&p->two->oid)) { /* deletion */
 228                         /*
 229                          * Either this is a true deletion (1), or it is part
 230                          * of an A/D pair (2), or D/A pair (3):
 231                          *
 232                          * (1) mp->local is uninitialized; set it to null_sha1
 233                          * (2) mp->local is not uninitialized; don't touch it
 234                          * (3) mp->local is uninitialized; set it to null_sha1
 235                          *     (will be overwritten by following addition)
 236                          */
 237                         if (oideq(&mp->local, &uninitialized))
 238                                 oidclr(&mp->local);
 239                 } else if (is_null_oid(&p->one->oid)) { /* addition */
 240                         /*
 241                          * Either this is a true addition (1), or it is part
 242                          * of an A/D pair (2), or D/A pair (3):
 243                          *
 244                          * (1) mp->local is uninitialized; set to p->two->sha1
 245                          * (2) mp->local is uninitialized; set to p->two->sha1
 246                          * (3) mp->local is null_sha1;     set to p->two->sha1
 247                          */
 248                         assert(is_null_oid(&mp->local) ||
 249                                oideq(&mp->local, &uninitialized));
 250                         oidcpy(&mp->local, &p->two->oid);
 251                 } else { /* modification */
 252                         /*
 253                          * This is a true modification. p->one->sha1 shall
 254                          * match mp->base, and mp->local shall be uninitialized.
 255                          * Set mp->local to p->two->sha1.
 256                          */
 257                         assert(oideq(&p->one->oid, &mp->base));
 258                         assert(oideq(&mp->local, &uninitialized));
 259                         oidcpy(&mp->local, &p->two->oid);
 260                 }
 261                 trace_printf("\t\tStored local change for %s: %.7s -> %.7s\n",
 262                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
 263                        oid_to_hex(&mp->local));
 264         }
 265         diff_flush(&opt);
 266 }
 267
 268 static void check_notes_merge_worktree(struct notes_merge_options *o)
 269 {
 270         if (!o->has_worktree) {
 271                 /*
 272                  * Must establish NOTES_MERGE_WORKTREE.
 273                  * Abort if NOTES_MERGE_WORKTREE already exists
 274                  */
 275                 if (file_exists(git_path(NOTES_MERGE_WORKTREE)) &&
 276                     !is_empty_dir(git_path(NOTES_MERGE_WORKTREE))) {
 277                         if (advice_enabled(ADVICE_RESOLVE_CONFLICT))
 278                                 die(_("You have not concluded your previous "
 279                                     "notes merge (%s exists).\nPlease, use "
 280                                     "'git notes merge --commit' or 'git notes "
 281                                     "merge --abort' to commit/abort the "
 282                                     "previous merge before you start a new "
 283                                     "notes merge."), git_path("NOTES_MERGE_*"));
 284                         else
 285                                 die(_("You have not concluded your notes merge "
 286                                     "(%s exists)."), git_path("NOTES_MERGE_*"));
 287                 }
 288
 289                 if (safe_create_leading_directories_const(git_path(
 290                                 NOTES_MERGE_WORKTREE "/.test")))
 291                         die_errno("unable to create directory %s",
 292                                   git_path(NOTES_MERGE_WORKTREE));
 293                 o->has_worktree = 1;
 294         } else if (!file_exists(git_path(NOTES_MERGE_WORKTREE)))
 295                 /* NOTES_MERGE_WORKTREE should already be established */
 296                 die("missing '%s'. This should not happen",
 297                     git_path(NOTES_MERGE_WORKTREE));
 298 }
 299
 300 static void write_buf_to_worktree(const struct object_id *obj,
 301                                   const char *buf, unsigned long size)
 302 {
 303         int fd;
 304         char *path = git_pathdup(NOTES_MERGE_WORKTREE "/%s", oid_to_hex(obj));
 305         if (safe_create_leading_directories_const(path))
 306                 die_errno("unable to create directory for '%s'", path);
 307
 308         fd = xopen(path, O_WRONLY | O_EXCL | O_CREAT, 0666);
 309
 310         while (size > 0) {
 311                 ssize_t ret = write_in_full(fd, buf, size);
 312                 if (ret < 0) {
 313                         /* Ignore epipe */
 314                         if (errno == EPIPE)
 315                                 break;
 316                         die_errno("notes-merge");
 317                 }
 318                 size -= ret;
 319                 buf += ret;
 320         }
 321
 322         close(fd);
 323         free(path);
 324 }
 325
 326 static void write_note_to_worktree(const struct object_id *obj,
 327                                    const struct object_id *note)
 328 {
 329         enum object_type type;
 330         unsigned long size;
 331         void *buf = read_object_file(note, &type, &size);
 332
 333         if (!buf)
 334                 die("cannot read note %s for object %s",
 335                     oid_to_hex(note), oid_to_hex(obj));
 336         if (type != OBJ_BLOB)
 337                 die("blob expected in note %s for object %s",
 338                     oid_to_hex(note), oid_to_hex(obj));
 339         write_buf_to_worktree(obj, buf, size);
 340         free(buf);
 341 }
 342
 343 static int ll_merge_in_worktree(struct notes_merge_options *o,
 344                                 struct notes_merge_pair *p)
 345 {
 346         mmbuffer_t result_buf;
 347         mmfile_t base, local, remote;
 348         enum ll_merge_result status;
 349
 350         read_mmblob(&base, &p->base);
 351         read_mmblob(&local, &p->local);
 352         read_mmblob(&remote, &p->remote);
 353
 354         status = ll_merge(&result_buf, oid_to_hex(&p->obj), &base, NULL,
 355                           &local, o->local_ref, &remote, o->remote_ref,
 356                           o->repo->index, NULL);
 357
 358         free(base.ptr);
 359         free(local.ptr);
 360         free(remote.ptr);
 361
 362         if (status == LL_MERGE_BINARY_CONFLICT)
 363                 warning("Cannot merge binary files: %s (%s vs. %s)",
 364                         oid_to_hex(&p->obj), o->local_ref, o->remote_ref);
 365         if ((status < 0) || !result_buf.ptr)
 366                 die("Failed to execute internal merge");
 367
 368         write_buf_to_worktree(&p->obj, result_buf.ptr, result_buf.size);
 369         free(result_buf.ptr);
 370
 371         return status;
 372 }
 373
 374 static int merge_one_change_manual(struct notes_merge_options *o,
 375                                    struct notes_merge_pair *p,
 376                                    struct notes_tree *t)
 377 {
 378         const char *lref = o->local_ref ? o->local_ref : "local version";
 379         const char *rref = o->remote_ref ? o->remote_ref : "remote version";
 380
 381         trace_printf("\t\t\tmerge_one_change_manual(obj = %.7s, base = %.7s, "
 382                "local = %.7s, remote = %.7s)\n",
 383                oid_to_hex(&p->obj), oid_to_hex(&p->base),
 384                oid_to_hex(&p->local), oid_to_hex(&p->remote));
 385
 386         /* add "Conflicts:" section to commit message first time through */
 387         if (!o->has_worktree)
 388                 strbuf_addstr(&(o->commit_msg), "\n\nConflicts:\n");
 389
 390         strbuf_addf(&(o->commit_msg), "\t%s\n", oid_to_hex(&p->obj));
 391
 392         if (o->verbosity >= 2)
 393                 printf("Auto-merging notes for %s\n", oid_to_hex(&p->obj));
 394         check_notes_merge_worktree(o);
 395         if (is_null_oid(&p->local)) {
 396                 /* D/F conflict, checkout p->remote */
 397                 assert(!is_null_oid(&p->remote));
 398                 if (o->verbosity >= 1)
 399                         printf("CONFLICT (delete/modify): Notes for object %s "
 400                                 "deleted in %s and modified in %s. Version from %s "
 401                                 "left in tree.\n",
 402                                 oid_to_hex(&p->obj), lref, rref, rref);
 403                 write_note_to_worktree(&p->obj, &p->remote);
 404         } else if (is_null_oid(&p->remote)) {
 405                 /* D/F conflict, checkout p->local */
 406                 assert(!is_null_oid(&p->local));
 407                 if (o->verbosity >= 1)
 408                         printf("CONFLICT (delete/modify): Notes for object %s "
 409                                 "deleted in %s and modified in %s. Version from %s "
 410                                 "left in tree.\n",
 411                                 oid_to_hex(&p->obj), rref, lref, lref);
 412                 write_note_to_worktree(&p->obj, &p->local);
 413         } else {
 414                 /* "regular" conflict, checkout result of ll_merge() */
 415                 const char *reason = "content";
 416                 if (is_null_oid(&p->base))
 417                         reason = "add/add";
 418                 assert(!is_null_oid(&p->local));
 419                 assert(!is_null_oid(&p->remote));
 420                 if (o->verbosity >= 1)
 421                         printf("CONFLICT (%s): Merge conflict in notes for "
 422                                 "object %s\n", reason,
 423                                 oid_to_hex(&p->obj));
 424                 ll_merge_in_worktree(o, p);
 425         }
 426
 427         trace_printf("\t\t\tremoving from partial merge result\n");
 428         remove_note(t, p->obj.hash);
 429
 430         return 1;
 431 }
 432
 433 static int merge_one_change(struct notes_merge_options *o,
 434                             struct notes_merge_pair *p, struct notes_tree *t)
 435 {
 436         /*
 437          * Return 0 if change is successfully resolved (stored in notes_tree).
 438          * Return 1 is change results in a conflict (NOT stored in notes_tree,
 439          * but instead written to NOTES_MERGE_WORKTREE with conflict markers).
 440          */
 441         switch (o->strategy) {
 442         case NOTES_MERGE_RESOLVE_MANUAL:
 443                 return merge_one_change_manual(o, p, t);
 444         case NOTES_MERGE_RESOLVE_OURS:
 445                 if (o->verbosity >= 2)
 446                         printf("Using local notes for %s\n",
 447                                                 oid_to_hex(&p->obj));
 448                 /* nothing to do */
 449                 return 0;
 450         case NOTES_MERGE_RESOLVE_THEIRS:
 451                 if (o->verbosity >= 2)
 452                         printf("Using remote notes for %s\n",
 453                                                 oid_to_hex(&p->obj));
 454                 if (add_note(t, &p->obj, &p->remote, combine_notes_overwrite))
 455                         BUG("combine_notes_overwrite failed");
 456                 return 0;
 457         case NOTES_MERGE_RESOLVE_UNION:
 458                 if (o->verbosity >= 2)
 459                         printf("Concatenating local and remote notes for %s\n",
 460                                                         oid_to_hex(&p->obj));
 461                 if (add_note(t, &p->obj, &p->remote, combine_notes_concatenate))
 462                         die("failed to concatenate notes "
 463                             "(combine_notes_concatenate)");
 464                 return 0;
 465         case NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ:
 466                 if (o->verbosity >= 2)
 467                         printf("Concatenating unique lines in local and remote "
 468                                 "notes for %s\n", oid_to_hex(&p->obj));
 469                 if (add_note(t, &p->obj, &p->remote, combine_notes_cat_sort_uniq))
 470                         die("failed to concatenate notes "
 471                             "(combine_notes_cat_sort_uniq)");
 472                 return 0;
 473         }
 474         die("Unknown strategy (%i).", o->strategy);
 475 }
 476
 477 static int merge_changes(struct notes_merge_options *o,
 478                          struct notes_merge_pair *changes, int *num_changes,
 479                          struct notes_tree *t)
 480 {
 481         int i, conflicts = 0;
 482
 483         trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
 484         for (i = 0; i < *num_changes; i++) {
 485                 struct notes_merge_pair *p = changes + i;
 486                 trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
 487                        oid_to_hex(&p->obj), oid_to_hex(&p->base),
 488                        oid_to_hex(&p->local),
 489                        oid_to_hex(&p->remote));
 490
 491                 if (oideq(&p->base, &p->remote)) {
 492                         /* no remote change; nothing to do */
 493                         trace_printf("\t\t\tskipping (no remote change)\n");
 494                 } else if (oideq(&p->local, &p->remote)) {
 495                         /* same change in local and remote; nothing to do */
 496                         trace_printf("\t\t\tskipping (local == remote)\n");
 497                 } else if (oideq(&p->local, &uninitialized) ||
 498                            oideq(&p->local, &p->base)) {
 499                         /* no local change; adopt remote change */
 500                         trace_printf("\t\t\tno local change, adopted remote\n");
 501                         if (add_note(t, &p->obj, &p->remote,
 502                                      combine_notes_overwrite))
 503                                 BUG("combine_notes_overwrite failed");
 504                 } else {
 505                         /* need file-level merge between local and remote */
 506                         trace_printf("\t\t\tneed content-level merge\n");
 507                         conflicts += merge_one_change(o, p, t);
 508                 }
 509         }
 510
 511         return conflicts;
 512 }
 513
 514 static int merge_from_diffs(struct notes_merge_options *o,
 515                             const struct object_id *base,
 516                             const struct object_id *local,
 517                             const struct object_id *remote,
 518                             struct notes_tree *t)
 519 {
 520         struct notes_merge_pair *changes;
 521         int num_changes, conflicts;
 522
 523         trace_printf("\tmerge_from_diffs(base = %.7s, local = %.7s, "
 524                "remote = %.7s)\n", oid_to_hex(base), oid_to_hex(local),
 525                oid_to_hex(remote));
 526
 527         changes = diff_tree_remote(o, base, remote, &num_changes);
 528         diff_tree_local(o, changes, num_changes, base, local);
 529
 530         conflicts = merge_changes(o, changes, &num_changes, t);
 531         free(changes);
 532
 533         if (o->verbosity >= 4)
 534                 printf(t->dirty ?
 535                        "Merge result: %i unmerged notes and a dirty notes tree\n" :
 536                        "Merge result: %i unmerged notes and a clean notes tree\n",
 537                        conflicts);
 538
 539         return conflicts ? -1 : 1;
 540 }
 541
 542 int notes_merge(struct notes_merge_options *o,
 543                 struct notes_tree *local_tree,
 544                 struct object_id *result_oid)
 545 {
 546         struct object_id local_oid, remote_oid;
 547         struct commit *local, *remote;
 548         struct commit_list *bases = NULL;
 549         const struct object_id *base_oid, *base_tree_oid;
 550         int result = 0;
 551
 552         assert(o->local_ref && o->remote_ref);
 553         assert(!strcmp(o->local_ref, local_tree->ref));
 554         oidclr(result_oid);
 555
 556         trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
 557                o->local_ref, o->remote_ref);
 558
 559         /* Dereference o->local_ref into local_sha1 */
 560         if (read_ref_full(o->local_ref, 0, &local_oid, NULL))
 561                 die("Failed to resolve local notes ref '%s'", o->local_ref);
 562         else if (!check_refname_format(o->local_ref, 0) &&
 563                 is_null_oid(&local_oid))
 564                 local = NULL; /* local_oid == null_oid indicates unborn ref */
 565         else if (!(local = lookup_commit_reference(o->repo, &local_oid)))
 566                 die("Could not parse local commit %s (%s)",
 567                     oid_to_hex(&local_oid), o->local_ref);
 568         trace_printf("\tlocal commit: %.7s\n", oid_to_hex(&local_oid));
 569
 570         /* Dereference o->remote_ref into remote_oid */
 571         if (get_oid(o->remote_ref, &remote_oid)) {
 572                 /*
 573                  * Failed to get remote_oid. If o->remote_ref looks like an
 574                  * unborn ref, perform the merge using an empty notes tree.
 575                  */
 576                 if (!check_refname_format(o->remote_ref, 0)) {
 577                         oidclr(&remote_oid);
 578                         remote = NULL;
 579                 } else {
 580                         die("Failed to resolve remote notes ref '%s'",
 581                             o->remote_ref);
 582                 }
 583         } else if (!(remote = lookup_commit_reference(o->repo, &remote_oid))) {
 584                 die("Could not parse remote commit %s (%s)",
 585                     oid_to_hex(&remote_oid), o->remote_ref);
 586         }
 587         trace_printf("\tremote commit: %.7s\n", oid_to_hex(&remote_oid));
 588
 589         if (!local && !remote)
 590                 die("Cannot merge empty notes ref (%s) into empty notes ref "
 591                     "(%s)", o->remote_ref, o->local_ref);
 592         if (!local) {
 593                 /* result == remote commit */
 594                 oidcpy(result_oid, &remote_oid);
 595                 goto found_result;
 596         }
 597         if (!remote) {
 598                 /* result == local commit */
 599                 oidcpy(result_oid, &local_oid);
 600                 goto found_result;
 601         }
 602         assert(local && remote);
 603
 604         /* Find merge bases */
 605         bases = get_merge_bases(local, remote);
 606         if (!bases) {
 607                 base_oid = null_oid();
 608                 base_tree_oid = the_hash_algo->empty_tree;
 609                 if (o->verbosity >= 4)
 610                         printf("No merge base found; doing history-less merge\n");
 611         } else if (!bases->next) {
 612                 base_oid = &bases->item->object.oid;
 613                 base_tree_oid = get_commit_tree_oid(bases->item);
 614                 if (o->verbosity >= 4)
 615                         printf("One merge base found (%.7s)\n",
 616                                oid_to_hex(base_oid));
 617         } else {
 618                 /* TODO: How to handle multiple merge-bases? */
 619                 base_oid = &bases->item->object.oid;
 620                 base_tree_oid = get_commit_tree_oid(bases->item);
 621                 if (o->verbosity >= 3)
 622                         printf("Multiple merge bases found. Using the first "
 623                                 "(%.7s)\n", oid_to_hex(base_oid));
 624         }
 625
 626         if (o->verbosity >= 4)
 627                 printf("Merging remote commit %.7s into local commit %.7s with "
 628                         "merge-base %.7s\n", oid_to_hex(&remote->object.oid),
 629                         oid_to_hex(&local->object.oid),
 630                         oid_to_hex(base_oid));
 631
 632         if (oideq(&remote->object.oid, base_oid)) {
 633                 /* Already merged; result == local commit */
 634                 if (o->verbosity >= 2)
 635                         printf_ln("Already up to date.");
 636                 oidcpy(result_oid, &local->object.oid);
 637                 goto found_result;
 638         }
 639         if (oideq(&local->object.oid, base_oid)) {
 640                 /* Fast-forward; result == remote commit */
 641                 if (o->verbosity >= 2)
 642                         printf("Fast-forward\n");
 643                 oidcpy(result_oid, &remote->object.oid);
 644                 goto found_result;
 645         }
 646
 647         result = merge_from_diffs(o, base_tree_oid,
 648                                   get_commit_tree_oid(local),
 649                                   get_commit_tree_oid(remote), local_tree);
 650
 651         if (result != 0) { /* non-trivial merge (with or without conflicts) */
 652                 /* Commit (partial) result */
 653                 struct commit_list *parents = NULL;
 654                 commit_list_insert(remote, &parents); /* LIFO order */
 655                 commit_list_insert(local, &parents);
 656                 create_notes_commit(o->repo, local_tree, parents, o->commit_msg.buf,
 657                                     o->commit_msg.len, result_oid);
 658         }
 659
 660 found_result:
 661         free_commit_list(bases);
 662         strbuf_release(&(o->commit_msg));
 663         trace_printf("notes_merge(): result = %i, result_oid = %.7s\n",
 664                result, oid_to_hex(result_oid));
 665         return result;
 666 }
 667
 668 int notes_merge_commit(struct notes_merge_options *o,
 669                        struct notes_tree *partial_tree,
 670                        struct commit *partial_commit,
 671                        struct object_id *result_oid)
 672 {
 673         /*
 674          * Iterate through files in .git/NOTES_MERGE_WORKTREE and add all
 675          * found notes to 'partial_tree'. Write the updated notes tree to
 676          * the DB, and commit the resulting tree object while reusing the
 677          * commit message and parents from 'partial_commit'.
 678          * Finally store the new commit object OID into 'result_oid'.
 679          */
 680         DIR *dir;
 681         struct dirent *e;
 682         struct strbuf path = STRBUF_INIT;
 683         const char *buffer = get_commit_buffer(partial_commit, NULL);
 684         const char *msg = strstr(buffer, "\n\n");
 685         int baselen;
 686
 687         git_path_buf(&path, NOTES_MERGE_WORKTREE);
 688         if (o->verbosity >= 3)
 689                 printf("Committing notes in notes merge worktree at %s\n",
 690                         path.buf);
 691
 692         if (!msg || msg[2] == '\0')
 693                 die("partial notes commit has empty message");
 694         msg += 2;
 695
 696         dir = opendir(path.buf);
 697         if (!dir)
 698                 die_errno("could not open %s", path.buf);
 699
 700         strbuf_addch(&path, '/');
 701         baselen = path.len;
 702         while ((e = readdir_skip_dot_and_dotdot(dir)) != NULL) {
 703                 struct stat st;
 704                 struct object_id obj_oid, blob_oid;
 705
 706                 if (get_oid_hex(e->d_name, &obj_oid)) {
 707                         if (o->verbosity >= 3)
 708                                 printf("Skipping non-SHA1 entry '%s%s'\n",
 709                                         path.buf, e->d_name);
 710                         continue;
 711                 }
 712
 713                 strbuf_addstr(&path, e->d_name);
 714                 /* write file as blob, and add to partial_tree */
 715                 if (stat(path.buf, &st))
 716                         die_errno("Failed to stat '%s'", path.buf);
 717                 if (index_path(o->repo->index, &blob_oid, path.buf, &st, HASH_WRITE_OBJECT))
 718                         die("Failed to write blob object from '%s'", path.buf);
 719                 if (add_note(partial_tree, &obj_oid, &blob_oid, NULL))
 720                         die("Failed to add resolved note '%s' to notes tree",
 721                             path.buf);
 722                 if (o->verbosity >= 4)
 723                         printf("Added resolved note for object %s: %s\n",
 724                                 oid_to_hex(&obj_oid), oid_to_hex(&blob_oid));
 725                 strbuf_setlen(&path, baselen);
 726         }
 727
 728         create_notes_commit(o->repo, partial_tree, partial_commit->parents, msg,
 729                             strlen(msg), result_oid);
 730         unuse_commit_buffer(partial_commit, buffer);
 731         if (o->verbosity >= 4)
 732                 printf("Finalized notes merge commit: %s\n",
 733                         oid_to_hex(result_oid));
 734         strbuf_release(&path);
 735         closedir(dir);
 736         return 0;
 737 }
 738
 739 int notes_merge_abort(struct notes_merge_options *o)
 740 {
 741         /*
 742          * Remove all files within .git/NOTES_MERGE_WORKTREE. We do not remove
 743          * the .git/NOTES_MERGE_WORKTREE directory itself, since it might be
 744          * the current working directory of the user.
 745          */
 746         struct strbuf buf = STRBUF_INIT;
 747         int ret;
 748
 749         git_path_buf(&buf, NOTES_MERGE_WORKTREE);
 750         if (o->verbosity >= 3)
 751                 printf("Removing notes merge worktree at %s/*\n", buf.buf);
 752         ret = remove_dir_recursively(&buf, REMOVE_DIR_KEEP_TOPLEVEL);
 753         strbuf_release(&buf);
 754         return ret;
 755 }