git.oblomov.eu Git - git/blob - 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
  16 struct notes_merge_pair {
  17         struct object_id obj, base, local, remote;
  18 };
  19
  20 void init_notes_merge_options(struct notes_merge_options *o)
  21 {
  22         memset(o, 0, sizeof(struct notes_merge_options));
  23         strbuf_init(&(o->commit_msg), 0);
  24         o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
  25 }
  26
  27 static int path_to_oid(const char *path, struct object_id *oid)
  28 {
  29         char hex_oid[GIT_SHA1_HEXSZ];
  30         int i = 0;
  31         while (*path && i < GIT_SHA1_HEXSZ) {
  32                 if (*path != '/')
  33                         hex_oid[i++] = *path;
  34                 path++;
  35         }
  36         if (*path || i != GIT_SHA1_HEXSZ)
  37                 return -1;
  38         return get_oid_hex(hex_oid, oid);
  39 }
  40
  41 static int verify_notes_filepair(struct diff_filepair *p, struct object_id *oid)
  42 {
  43         switch (p->status) {
  44         case DIFF_STATUS_MODIFIED:
  45                 assert(p->one->mode == p->two->mode);
  46                 assert(!is_null_oid(&p->one->oid));
  47                 assert(!is_null_oid(&p->two->oid));
  48                 break;
  49         case DIFF_STATUS_ADDED:
  50                 assert(is_null_oid(&p->one->oid));
  51                 break;
  52         case DIFF_STATUS_DELETED:
  53                 assert(is_null_oid(&p->two->oid));
  54                 break;
  55         default:
  56                 return -1;
  57         }
  58         assert(!strcmp(p->one->path, p->two->path));
  59         return path_to_oid(p->one->path, oid);
  60 }
  61
  62 static struct notes_merge_pair *find_notes_merge_pair_pos(
  63                 struct notes_merge_pair *list, int len, struct object_id *obj,
  64                 int insert_new, int *occupied)
  65 {
  66         /*
  67          * Both diff_tree_remote() and diff_tree_local() tend to process
  68          * merge_pairs in ascending order. Therefore, cache last returned
  69          * index, and search sequentially from there until the appropriate
  70          * position is found.
  71          *
  72          * Since inserts only happen from diff_tree_remote() (which mainly
  73          * _appends_), we don't care that inserting into the middle of the
  74          * list is expensive (using memmove()).
  75          */
  76         static int last_index;
  77         int i = last_index < len ? last_index : len - 1;
  78         int prev_cmp = 0, cmp = -1;
  79         while (i >= 0 && i < len) {
  80                 cmp = oidcmp(obj, &list[i].obj);
  81                 if (!cmp) /* obj belongs @ i */
  82                         break;
  83                 else if (cmp < 0 && prev_cmp <= 0) /* obj belongs < i */
  84                         i--;
  85                 else if (cmp < 0) /* obj belongs between i-1 and i */
  86                         break;
  87                 else if (cmp > 0 && prev_cmp >= 0) /* obj belongs > i */
  88                         i++;
  89                 else /* if (cmp > 0) */ { /* obj belongs between i and i+1 */
  90                         i++;
  91                         break;
  92                 }
  93                 prev_cmp = cmp;
  94         }
  95         if (i < 0)
  96                 i = 0;
  97         /* obj belongs at, or immediately preceding, index i (0 <= i <= len) */
  98
  99         if (!cmp)
 100                 *occupied = 1;
 101         else {
 102                 *occupied = 0;
 103                 if (insert_new && i < len) {
 104                         MOVE_ARRAY(list + i + 1, list + i, len - i);
 105                         memset(list + i, 0, sizeof(struct notes_merge_pair));
 106                 }
 107         }
 108         last_index = i;
 109         return list + i;
 110 }
 111
 112 static struct object_id uninitialized = {
 113         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" \
 114         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
 115 };
 116
 117 static struct notes_merge_pair *diff_tree_remote(struct notes_merge_options *o,
 118                                                  const struct object_id *base,
 119                                                  const struct object_id *remote,
 120                                                  int *num_changes)
 121 {
 122         struct diff_options opt;
 123         struct notes_merge_pair *changes;
 124         int i, len = 0;
 125
 126         trace_printf("\tdiff_tree_remote(base = %.7s, remote = %.7s)\n",
 127                oid_to_hex(base), oid_to_hex(remote));
 128
 129         diff_setup(&opt);
 130         opt.flags.recursive = 1;
 131         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 132         diff_setup_done(&opt);
 133         diff_tree_oid(base, remote, "", &opt);
 134         diffcore_std(&opt);
 135
 136         changes = xcalloc(diff_queued_diff.nr, sizeof(struct notes_merge_pair));
 137
 138         for (i = 0; i < diff_queued_diff.nr; i++) {
 139                 struct diff_filepair *p = diff_queued_diff.queue[i];
 140                 struct notes_merge_pair *mp;
 141                 int occupied;
 142                 struct object_id obj;
 143
 144                 if (verify_notes_filepair(p, &obj)) {
 145                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 146                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 147                                p->status, oid_to_hex(&p->one->oid),
 148                                oid_to_hex(&p->two->oid));
 149                         continue;
 150                 }
 151                 mp = find_notes_merge_pair_pos(changes, len, &obj, 1, &occupied);
 152                 if (occupied) {
 153                         /* We've found an addition/deletion pair */
 154                         assert(!oidcmp(&mp->obj, &obj));
 155                         if (is_null_oid(&p->one->oid)) { /* addition */
 156                                 assert(is_null_oid(&mp->remote));
 157                                 oidcpy(&mp->remote, &p->two->oid);
 158                         } else if (is_null_oid(&p->two->oid)) { /* deletion */
 159                                 assert(is_null_oid(&mp->base));
 160                                 oidcpy(&mp->base, &p->one->oid);
 161                         } else
 162                                 assert(!"Invalid existing change recorded");
 163                 } else {
 164                         oidcpy(&mp->obj, &obj);
 165                         oidcpy(&mp->base, &p->one->oid);
 166                         oidcpy(&mp->local, &uninitialized);
 167                         oidcpy(&mp->remote, &p->two->oid);
 168                         len++;
 169                 }
 170                 trace_printf("\t\tStored remote change for %s: %.7s -> %.7s\n",
 171                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
 172                        oid_to_hex(&mp->remote));
 173         }
 174         diff_flush(&opt);
 175         clear_pathspec(&opt.pathspec);
 176
 177         *num_changes = len;
 178         return changes;
 179 }
 180
 181 static void diff_tree_local(struct notes_merge_options *o,
 182                             struct notes_merge_pair *changes, int len,
 183                             const struct object_id *base,
 184                             const struct object_id *local)
 185 {
 186         struct diff_options opt;
 187         int i;
 188
 189         trace_printf("\tdiff_tree_local(len = %i, base = %.7s, local = %.7s)\n",
 190                len, oid_to_hex(base), oid_to_hex(local));
 191
 192         diff_setup(&opt);
 193         opt.flags.recursive = 1;
 194         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 195         diff_setup_done(&opt);
 196         diff_tree_oid(base, local, "", &opt);
 197         diffcore_std(&opt);
 198
 199         for (i = 0; i < diff_queued_diff.nr; i++) {
 200                 struct diff_filepair *p = diff_queued_diff.queue[i];
 201                 struct notes_merge_pair *mp;
 202                 int match;
 203                 struct object_id obj;
 204
 205                 if (verify_notes_filepair(p, &obj)) {
 206                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 207                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 208                                p->status, oid_to_hex(&p->one->oid),
 209                                oid_to_hex(&p->two->oid));
 210                         continue;
 211                 }
 212                 mp = find_notes_merge_pair_pos(changes, len, &obj, 0, &match);
 213                 if (!match) {
 214                         trace_printf("\t\tIgnoring local-only change for %s: "
 215                                "%.7s -> %.7s\n", oid_to_hex(&obj),
 216                                oid_to_hex(&p->one->oid),
 217                                oid_to_hex(&p->two->oid));
 218                         continue;
 219                 }
 220
 221                 assert(!oidcmp(&mp->obj, &obj));
 222                 if (is_null_oid(&p->two->oid)) { /* deletion */
 223                         /*
 224                          * Either this is a true deletion (1), or it is part
 225                          * of an A/D pair (2), or D/A pair (3):
 226                          *
 227                          * (1) mp->local is uninitialized; set it to null_sha1
 228                          * (2) mp->local is not uninitialized; don't touch it
 229                          * (3) mp->local is uninitialized; set it to null_sha1
 230                          *     (will be overwritten by following addition)
 231                          */
 232                         if (!oidcmp(&mp->local, &uninitialized))
 233                                 oidclr(&mp->local);
 234                 } else if (is_null_oid(&p->one->oid)) { /* addition */
 235                         /*
 236                          * Either this is a true addition (1), or it is part
 237                          * of an A/D pair (2), or D/A pair (3):
 238                          *
 239                          * (1) mp->local is uninitialized; set to p->two->sha1
 240                          * (2) mp->local is uninitialized; set to p->two->sha1
 241                          * (3) mp->local is null_sha1;     set to p->two->sha1
 242                          */
 243                         assert(is_null_oid(&mp->local) ||
 244                                !oidcmp(&mp->local, &uninitialized));
 245                         oidcpy(&mp->local, &p->two->oid);
 246                 } else { /* modification */
 247                         /*
 248                          * This is a true modification. p->one->sha1 shall
 249                          * match mp->base, and mp->local shall be uninitialized.
 250                          * Set mp->local to p->two->sha1.
 251                          */
 252                         assert(!oidcmp(&p->one->oid, &mp->base));
 253                         assert(!oidcmp(&mp->local, &uninitialized));
 254                         oidcpy(&mp->local, &p->two->oid);
 255                 }
 256                 trace_printf("\t\tStored local change for %s: %.7s -> %.7s\n",
 257                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
 258                        oid_to_hex(&mp->local));
 259         }
 260         diff_flush(&opt);
 261         clear_pathspec(&opt.pathspec);
 262 }
 263
 264 static void check_notes_merge_worktree(struct notes_merge_options *o)
 265 {
 266         if (!o->has_worktree) {
 267                 /*
 268                  * Must establish NOTES_MERGE_WORKTREE.
 269                  * Abort if NOTES_MERGE_WORKTREE already exists
 270                  */
 271                 if (file_exists(git_path(NOTES_MERGE_WORKTREE)) &&
 272                     !is_empty_dir(git_path(NOTES_MERGE_WORKTREE))) {
 273                         if (advice_resolve_conflict)
 274                                 die(_("You have not concluded your previous "
 275                                     "notes merge (%s exists).\nPlease, use "
 276                                     "'git notes merge --commit' or 'git notes "
 277                                     "merge --abort' to commit/abort the "
 278                                     "previous merge before you start a new "
 279                                     "notes merge."), git_path("NOTES_MERGE_*"));
 280                         else
 281                                 die(_("You have not concluded your notes merge "
 282                                     "(%s exists)."), git_path("NOTES_MERGE_*"));
 283                 }
 284
 285                 if (safe_create_leading_directories_const(git_path(
 286                                 NOTES_MERGE_WORKTREE "/.test")))
 287                         die_errno("unable to create directory %s",
 288                                   git_path(NOTES_MERGE_WORKTREE));
 289                 o->has_worktree = 1;
 290         } else if (!file_exists(git_path(NOTES_MERGE_WORKTREE)))
 291                 /* NOTES_MERGE_WORKTREE should already be established */
 292                 die("missing '%s'. This should not happen",
 293                     git_path(NOTES_MERGE_WORKTREE));
 294 }
 295
 296 static void write_buf_to_worktree(const struct object_id *obj,
 297                                   const char *buf, unsigned long size)
 298 {
 299         int fd;
 300         char *path = git_pathdup(NOTES_MERGE_WORKTREE "/%s", oid_to_hex(obj));
 301         if (safe_create_leading_directories_const(path))
 302                 die_errno("unable to create directory for '%s'", path);
 303
 304         fd = xopen(path, O_WRONLY | O_EXCL | O_CREAT, 0666);
 305
 306         while (size > 0) {
 307                 ssize_t ret = write_in_full(fd, buf, size);
 308                 if (ret < 0) {
 309                         /* Ignore epipe */
 310                         if (errno == EPIPE)
 311                                 break;
 312                         die_errno("notes-merge");
 313                 }
 314                 size -= ret;
 315                 buf += ret;
 316         }
 317
 318         close(fd);
 319         free(path);
 320 }
 321
 322 static void write_note_to_worktree(const struct object_id *obj,
 323                                    const struct object_id *note)
 324 {
 325         enum object_type type;
 326         unsigned long size;
 327         void *buf = read_object_file(note, &type, &size);
 328
 329         if (!buf)
 330                 die("cannot read note %s for object %s",
 331                     oid_to_hex(note), oid_to_hex(obj));
 332         if (type != OBJ_BLOB)
 333                 die("blob expected in note %s for object %s",
 334                     oid_to_hex(note), oid_to_hex(obj));
 335         write_buf_to_worktree(obj, buf, size);
 336         free(buf);
 337 }
 338
 339 static int ll_merge_in_worktree(struct notes_merge_options *o,
 340                                 struct notes_merge_pair *p)
 341 {
 342         mmbuffer_t result_buf;
 343         mmfile_t base, local, remote;
 344         int status;
 345
 346         read_mmblob(&base, &p->base);
 347         read_mmblob(&local, &p->local);
 348         read_mmblob(&remote, &p->remote);
 349
 350         status = ll_merge(&result_buf, oid_to_hex(&p->obj), &base, NULL,
 351                           &local, o->local_ref, &remote, o->remote_ref, NULL);
 352
 353         free(base.ptr);
 354         free(local.ptr);
 355         free(remote.ptr);
 356
 357         if ((status < 0) || !result_buf.ptr)
 358                 die("Failed to execute internal merge");
 359
 360         write_buf_to_worktree(&p->obj, result_buf.ptr, result_buf.size);
 361         free(result_buf.ptr);
 362
 363         return status;
 364 }
 365
 366 static int merge_one_change_manual(struct notes_merge_options *o,
 367                                    struct notes_merge_pair *p,
 368                                    struct notes_tree *t)
 369 {
 370         const char *lref = o->local_ref ? o->local_ref : "local version";
 371         const char *rref = o->remote_ref ? o->remote_ref : "remote version";
 372
 373         trace_printf("\t\t\tmerge_one_change_manual(obj = %.7s, base = %.7s, "
 374                "local = %.7s, remote = %.7s)\n",
 375                oid_to_hex(&p->obj), oid_to_hex(&p->base),
 376                oid_to_hex(&p->local), oid_to_hex(&p->remote));
 377
 378         /* add "Conflicts:" section to commit message first time through */
 379         if (!o->has_worktree)
 380                 strbuf_addstr(&(o->commit_msg), "\n\nConflicts:\n");
 381
 382         strbuf_addf(&(o->commit_msg), "\t%s\n", oid_to_hex(&p->obj));
 383
 384         if (o->verbosity >= 2)
 385                 printf("Auto-merging notes for %s\n", oid_to_hex(&p->obj));
 386         check_notes_merge_worktree(o);
 387         if (is_null_oid(&p->local)) {
 388                 /* D/F conflict, checkout p->remote */
 389                 assert(!is_null_oid(&p->remote));
 390                 if (o->verbosity >= 1)
 391                         printf("CONFLICT (delete/modify): Notes for object %s "
 392                                 "deleted in %s and modified in %s. Version from %s "
 393                                 "left in tree.\n",
 394                                 oid_to_hex(&p->obj), lref, rref, rref);
 395                 write_note_to_worktree(&p->obj, &p->remote);
 396         } else if (is_null_oid(&p->remote)) {
 397                 /* D/F conflict, checkout p->local */
 398                 assert(!is_null_oid(&p->local));
 399                 if (o->verbosity >= 1)
 400                         printf("CONFLICT (delete/modify): Notes for object %s "
 401                                 "deleted in %s and modified in %s. Version from %s "
 402                                 "left in tree.\n",
 403                                 oid_to_hex(&p->obj), rref, lref, lref);
 404                 write_note_to_worktree(&p->obj, &p->local);
 405         } else {
 406                 /* "regular" conflict, checkout result of ll_merge() */
 407                 const char *reason = "content";
 408                 if (is_null_oid(&p->base))
 409                         reason = "add/add";
 410                 assert(!is_null_oid(&p->local));
 411                 assert(!is_null_oid(&p->remote));
 412                 if (o->verbosity >= 1)
 413                         printf("CONFLICT (%s): Merge conflict in notes for "
 414                                 "object %s\n", reason,
 415                                 oid_to_hex(&p->obj));
 416                 ll_merge_in_worktree(o, p);
 417         }
 418
 419         trace_printf("\t\t\tremoving from partial merge result\n");
 420         remove_note(t, p->obj.hash);
 421
 422         return 1;
 423 }
 424
 425 static int merge_one_change(struct notes_merge_options *o,
 426                             struct notes_merge_pair *p, struct notes_tree *t)
 427 {
 428         /*
 429          * Return 0 if change is successfully resolved (stored in notes_tree).
 430          * Return 1 is change results in a conflict (NOT stored in notes_tree,
 431          * but instead written to NOTES_MERGE_WORKTREE with conflict markers).
 432          */
 433         switch (o->strategy) {
 434         case NOTES_MERGE_RESOLVE_MANUAL:
 435                 return merge_one_change_manual(o, p, t);
 436         case NOTES_MERGE_RESOLVE_OURS:
 437                 if (o->verbosity >= 2)
 438                         printf("Using local notes for %s\n",
 439                                                 oid_to_hex(&p->obj));
 440                 /* nothing to do */
 441                 return 0;
 442         case NOTES_MERGE_RESOLVE_THEIRS:
 443                 if (o->verbosity >= 2)
 444                         printf("Using remote notes for %s\n",
 445                                                 oid_to_hex(&p->obj));
 446                 if (add_note(t, &p->obj, &p->remote, combine_notes_overwrite))
 447                         BUG("combine_notes_overwrite failed");
 448                 return 0;
 449         case NOTES_MERGE_RESOLVE_UNION:
 450                 if (o->verbosity >= 2)
 451                         printf("Concatenating local and remote notes for %s\n",
 452                                                         oid_to_hex(&p->obj));
 453                 if (add_note(t, &p->obj, &p->remote, combine_notes_concatenate))
 454                         die("failed to concatenate notes "
 455                             "(combine_notes_concatenate)");
 456                 return 0;
 457         case NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ:
 458                 if (o->verbosity >= 2)
 459                         printf("Concatenating unique lines in local and remote "
 460                                 "notes for %s\n", oid_to_hex(&p->obj));
 461                 if (add_note(t, &p->obj, &p->remote, combine_notes_cat_sort_uniq))
 462                         die("failed to concatenate notes "
 463                             "(combine_notes_cat_sort_uniq)");
 464                 return 0;
 465         }
 466         die("Unknown strategy (%i).", o->strategy);
 467 }
 468
 469 static int merge_changes(struct notes_merge_options *o,
 470                          struct notes_merge_pair *changes, int *num_changes,
 471                          struct notes_tree *t)
 472 {
 473         int i, conflicts = 0;
 474
 475         trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
 476         for (i = 0; i < *num_changes; i++) {
 477                 struct notes_merge_pair *p = changes + i;
 478                 trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
 479                        oid_to_hex(&p->obj), oid_to_hex(&p->base),
 480                        oid_to_hex(&p->local),
 481                        oid_to_hex(&p->remote));
 482
 483                 if (!oidcmp(&p->base, &p->remote)) {
 484                         /* no remote change; nothing to do */
 485                         trace_printf("\t\t\tskipping (no remote change)\n");
 486                 } else if (!oidcmp(&p->local, &p->remote)) {
 487                         /* same change in local and remote; nothing to do */
 488                         trace_printf("\t\t\tskipping (local == remote)\n");
 489                 } else if (!oidcmp(&p->local, &uninitialized) ||
 490                            !oidcmp(&p->local, &p->base)) {
 491                         /* no local change; adopt remote change */
 492                         trace_printf("\t\t\tno local change, adopted remote\n");
 493                         if (add_note(t, &p->obj, &p->remote,
 494                                      combine_notes_overwrite))
 495                                 BUG("combine_notes_overwrite failed");
 496                 } else {
 497                         /* need file-level merge between local and remote */
 498                         trace_printf("\t\t\tneed content-level merge\n");
 499                         conflicts += merge_one_change(o, p, t);
 500                 }
 501         }
 502
 503         return conflicts;
 504 }
 505
 506 static int merge_from_diffs(struct notes_merge_options *o,
 507                             const struct object_id *base,
 508                             const struct object_id *local,
 509                             const struct object_id *remote,
 510                             struct notes_tree *t)
 511 {
 512         struct notes_merge_pair *changes;
 513         int num_changes, conflicts;
 514
 515         trace_printf("\tmerge_from_diffs(base = %.7s, local = %.7s, "
 516                "remote = %.7s)\n", oid_to_hex(base), oid_to_hex(local),
 517                oid_to_hex(remote));
 518
 519         changes = diff_tree_remote(o, base, remote, &num_changes);
 520         diff_tree_local(o, changes, num_changes, base, local);
 521
 522         conflicts = merge_changes(o, changes, &num_changes, t);
 523         free(changes);
 524
 525         if (o->verbosity >= 4)
 526                 printf(t->dirty ?
 527                        "Merge result: %i unmerged notes and a dirty notes tree\n" :
 528                        "Merge result: %i unmerged notes and a clean notes tree\n",
 529                        conflicts);
 530
 531         return conflicts ? -1 : 1;
 532 }
 533
 534 int notes_merge(struct notes_merge_options *o,
 535                 struct notes_tree *local_tree,
 536                 struct object_id *result_oid)
 537 {
 538         struct object_id local_oid, remote_oid;
 539         struct commit *local, *remote;
 540         struct commit_list *bases = NULL;
 541         const struct object_id *base_oid, *base_tree_oid;
 542         int result = 0;
 543
 544         assert(o->local_ref && o->remote_ref);
 545         assert(!strcmp(o->local_ref, local_tree->ref));
 546         oidclr(result_oid);
 547
 548         trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
 549                o->local_ref, o->remote_ref);
 550
 551         /* Dereference o->local_ref into local_sha1 */
 552         if (read_ref_full(o->local_ref, 0, &local_oid, NULL))
 553                 die("Failed to resolve local notes ref '%s'", o->local_ref);
 554         else if (!check_refname_format(o->local_ref, 0) &&
 555                 is_null_oid(&local_oid))
 556                 local = NULL; /* local_oid == null_oid indicates unborn ref */
 557         else if (!(local = lookup_commit_reference(the_repository, &local_oid)))
 558                 die("Could not parse local commit %s (%s)",
 559                     oid_to_hex(&local_oid), o->local_ref);
 560         trace_printf("\tlocal commit: %.7s\n", oid_to_hex(&local_oid));
 561
 562         /* Dereference o->remote_ref into remote_oid */
 563         if (get_oid(o->remote_ref, &remote_oid)) {
 564                 /*
 565                  * Failed to get remote_oid. If o->remote_ref looks like an
 566                  * unborn ref, perform the merge using an empty notes tree.
 567                  */
 568                 if (!check_refname_format(o->remote_ref, 0)) {
 569                         oidclr(&remote_oid);
 570                         remote = NULL;
 571                 } else {
 572                         die("Failed to resolve remote notes ref '%s'",
 573                             o->remote_ref);
 574                 }
 575         } else if (!(remote = lookup_commit_reference(the_repository, &remote_oid))) {
 576                 die("Could not parse remote commit %s (%s)",
 577                     oid_to_hex(&remote_oid), o->remote_ref);
 578         }
 579         trace_printf("\tremote commit: %.7s\n", oid_to_hex(&remote_oid));
 580
 581         if (!local && !remote)
 582                 die("Cannot merge empty notes ref (%s) into empty notes ref "
 583                     "(%s)", o->remote_ref, o->local_ref);
 584         if (!local) {
 585                 /* result == remote commit */
 586                 oidcpy(result_oid, &remote_oid);
 587                 goto found_result;
 588         }
 589         if (!remote) {
 590                 /* result == local commit */
 591                 oidcpy(result_oid, &local_oid);
 592                 goto found_result;
 593         }
 594         assert(local && remote);
 595
 596         /* Find merge bases */
 597         bases = get_merge_bases(local, remote);
 598         if (!bases) {
 599                 base_oid = &null_oid;
 600                 base_tree_oid = the_hash_algo->empty_tree;
 601                 if (o->verbosity >= 4)
 602                         printf("No merge base found; doing history-less merge\n");
 603         } else if (!bases->next) {
 604                 base_oid = &bases->item->object.oid;
 605                 base_tree_oid = get_commit_tree_oid(bases->item);
 606                 if (o->verbosity >= 4)
 607                         printf("One merge base found (%.7s)\n",
 608                                oid_to_hex(base_oid));
 609         } else {
 610                 /* TODO: How to handle multiple merge-bases? */
 611                 base_oid = &bases->item->object.oid;
 612                 base_tree_oid = get_commit_tree_oid(bases->item);
 613                 if (o->verbosity >= 3)
 614                         printf("Multiple merge bases found. Using the first "
 615                                 "(%.7s)\n", oid_to_hex(base_oid));
 616         }
 617
 618         if (o->verbosity >= 4)
 619                 printf("Merging remote commit %.7s into local commit %.7s with "
 620                         "merge-base %.7s\n", oid_to_hex(&remote->object.oid),
 621                         oid_to_hex(&local->object.oid),
 622                         oid_to_hex(base_oid));
 623
 624         if (!oidcmp(&remote->object.oid, base_oid)) {
 625                 /* Already merged; result == local commit */
 626                 if (o->verbosity >= 2)
 627                         printf("Already up to date!\n");
 628                 oidcpy(result_oid, &local->object.oid);
 629                 goto found_result;
 630         }
 631         if (!oidcmp(&local->object.oid, base_oid)) {
 632                 /* Fast-forward; result == remote commit */
 633                 if (o->verbosity >= 2)
 634                         printf("Fast-forward\n");
 635                 oidcpy(result_oid, &remote->object.oid);
 636                 goto found_result;
 637         }
 638
 639         result = merge_from_diffs(o, base_tree_oid,
 640                                   get_commit_tree_oid(local),
 641                                   get_commit_tree_oid(remote), local_tree);
 642
 643         if (result != 0) { /* non-trivial merge (with or without conflicts) */
 644                 /* Commit (partial) result */
 645                 struct commit_list *parents = NULL;
 646                 commit_list_insert(remote, &parents); /* LIFO order */
 647                 commit_list_insert(local, &parents);
 648                 create_notes_commit(local_tree, parents, o->commit_msg.buf,
 649                                     o->commit_msg.len, result_oid);
 650         }
 651
 652 found_result:
 653         free_commit_list(bases);
 654         strbuf_release(&(o->commit_msg));
 655         trace_printf("notes_merge(): result = %i, result_oid = %.7s\n",
 656                result, oid_to_hex(result_oid));
 657         return result;
 658 }
 659
 660 int notes_merge_commit(struct notes_merge_options *o,
 661                        struct notes_tree *partial_tree,
 662                        struct commit *partial_commit,
 663                        struct object_id *result_oid)
 664 {
 665         /*
 666          * Iterate through files in .git/NOTES_MERGE_WORKTREE and add all
 667          * found notes to 'partial_tree'. Write the updated notes tree to
 668          * the DB, and commit the resulting tree object while reusing the
 669          * commit message and parents from 'partial_commit'.
 670          * Finally store the new commit object OID into 'result_oid'.
 671          */
 672         DIR *dir;
 673         struct dirent *e;
 674         struct strbuf path = STRBUF_INIT;
 675         const char *buffer = get_commit_buffer(partial_commit, NULL);
 676         const char *msg = strstr(buffer, "\n\n");
 677         int baselen;
 678
 679         git_path_buf(&path, NOTES_MERGE_WORKTREE);
 680         if (o->verbosity >= 3)
 681                 printf("Committing notes in notes merge worktree at %s\n",
 682                         path.buf);
 683
 684         if (!msg || msg[2] == '\0')
 685                 die("partial notes commit has empty message");
 686         msg += 2;
 687
 688         dir = opendir(path.buf);
 689         if (!dir)
 690                 die_errno("could not open %s", path.buf);
 691
 692         strbuf_addch(&path, '/');
 693         baselen = path.len;
 694         while ((e = readdir(dir)) != NULL) {
 695                 struct stat st;
 696                 struct object_id obj_oid, blob_oid;
 697
 698                 if (is_dot_or_dotdot(e->d_name))
 699                         continue;
 700
 701                 if (get_oid_hex(e->d_name, &obj_oid)) {
 702                         if (o->verbosity >= 3)
 703                                 printf("Skipping non-SHA1 entry '%s%s'\n",
 704                                         path.buf, e->d_name);
 705                         continue;
 706                 }
 707
 708                 strbuf_addstr(&path, e->d_name);
 709                 /* write file as blob, and add to partial_tree */
 710                 if (stat(path.buf, &st))
 711                         die_errno("Failed to stat '%s'", path.buf);
 712                 if (index_path(&blob_oid, path.buf, &st, HASH_WRITE_OBJECT))
 713                         die("Failed to write blob object from '%s'", path.buf);
 714                 if (add_note(partial_tree, &obj_oid, &blob_oid, NULL))
 715                         die("Failed to add resolved note '%s' to notes tree",
 716                             path.buf);
 717                 if (o->verbosity >= 4)
 718                         printf("Added resolved note for object %s: %s\n",
 719                                 oid_to_hex(&obj_oid), oid_to_hex(&blob_oid));
 720                 strbuf_setlen(&path, baselen);
 721         }
 722
 723         create_notes_commit(partial_tree, partial_commit->parents, msg,
 724                             strlen(msg), result_oid);
 725         unuse_commit_buffer(partial_commit, buffer);
 726         if (o->verbosity >= 4)
 727                 printf("Finalized notes merge commit: %s\n",
 728                         oid_to_hex(result_oid));
 729         strbuf_release(&path);
 730         closedir(dir);
 731         return 0;
 732 }
 733
 734 int notes_merge_abort(struct notes_merge_options *o)
 735 {
 736         /*
 737          * Remove all files within .git/NOTES_MERGE_WORKTREE. We do not remove
 738          * the .git/NOTES_MERGE_WORKTREE directory itself, since it might be
 739          * the current working directory of the user.
 740          */
 741         struct strbuf buf = STRBUF_INIT;
 742         int ret;
 743
 744         git_path_buf(&buf, NOTES_MERGE_WORKTREE);
 745         if (o->verbosity >= 3)
 746                 printf("Removing notes merge worktree at %s/*\n", buf.buf);
 747         ret = remove_dir_recursively(&buf, REMOVE_DIR_KEEP_TOPLEVEL);
 748         strbuf_release(&buf);
 749         return ret;
 750 }