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 "diff.h"
   6 #include "diffcore.h"
   7 #include "xdiff-interface.h"
   8 #include "ll-merge.h"
   9 #include "dir.h"
  10 #include "notes.h"
  11 #include "notes-merge.h"
  12 #include "strbuf.h"
  13 #include "notes-utils.h"
  14
  15 struct notes_merge_pair {
  16         struct object_id obj, base, local, remote;
  17 };
  18
  19 void init_notes_merge_options(struct notes_merge_options *o)
  20 {
  21         memset(o, 0, sizeof(struct notes_merge_options));
  22         strbuf_init(&(o->commit_msg), 0);
  23         o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
  24 }
  25
  26 static int path_to_oid(const char *path, struct object_id *oid)
  27 {
  28         char hex_oid[GIT_SHA1_HEXSZ];
  29         int i = 0;
  30         while (*path && i < GIT_SHA1_HEXSZ) {
  31                 if (*path != '/')
  32                         hex_oid[i++] = *path;
  33                 path++;
  34         }
  35         if (*path || i != GIT_SHA1_HEXSZ)
  36                 return -1;
  37         return get_oid_hex(hex_oid, oid);
  38 }
  39
  40 static int verify_notes_filepair(struct diff_filepair *p, struct object_id *oid)
  41 {
  42         switch (p->status) {
  43         case DIFF_STATUS_MODIFIED:
  44                 assert(p->one->mode == p->two->mode);
  45                 assert(!is_null_oid(&p->one->oid));
  46                 assert(!is_null_oid(&p->two->oid));
  47                 break;
  48         case DIFF_STATUS_ADDED:
  49                 assert(is_null_oid(&p->one->oid));
  50                 break;
  51         case DIFF_STATUS_DELETED:
  52                 assert(is_null_oid(&p->two->oid));
  53                 break;
  54         default:
  55                 return -1;
  56         }
  57         assert(!strcmp(p->one->path, p->two->path));
  58         return path_to_oid(p->one->path, oid);
  59 }
  60
  61 static struct notes_merge_pair *find_notes_merge_pair_pos(
  62                 struct notes_merge_pair *list, int len, struct object_id *obj,
  63                 int insert_new, int *occupied)
  64 {
  65         /*
  66          * Both diff_tree_remote() and diff_tree_local() tend to process
  67          * merge_pairs in ascending order. Therefore, cache last returned
  68          * index, and search sequentially from there until the appropriate
  69          * position is found.
  70          *
  71          * Since inserts only happen from diff_tree_remote() (which mainly
  72          * _appends_), we don't care that inserting into the middle of the
  73          * list is expensive (using memmove()).
  74          */
  75         static int last_index;
  76         int i = last_index < len ? last_index : len - 1;
  77         int prev_cmp = 0, cmp = -1;
  78         while (i >= 0 && i < len) {
  79                 cmp = oidcmp(obj, &list[i].obj);
  80                 if (!cmp) /* obj belongs @ i */
  81                         break;
  82                 else if (cmp < 0 && prev_cmp <= 0) /* obj belongs < i */
  83                         i--;
  84                 else if (cmp < 0) /* obj belongs between i-1 and 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 and i+1 */
  89                         i++;
  90                         break;
  91                 }
  92                 prev_cmp = cmp;
  93         }
  94         if (i < 0)
  95                 i = 0;
  96         /* obj belongs at, or immediately preceding, index i (0 <= i <= len) */
  97
  98         if (!cmp)
  99                 *occupied = 1;
 100         else {
 101                 *occupied = 0;
 102                 if (insert_new && i < len) {
 103                         MOVE_ARRAY(list + i + 1, list + i, len - i);
 104                         memset(list + i, 0, sizeof(struct notes_merge_pair));
 105                 }
 106         }
 107         last_index = i;
 108         return list + i;
 109 }
 110
 111 static struct object_id uninitialized = {
 112         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" \
 113         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff"
 114 };
 115
 116 static struct notes_merge_pair *diff_tree_remote(struct notes_merge_options *o,
 117                                                  const struct object_id *base,
 118                                                  const struct object_id *remote,
 119                                                  int *num_changes)
 120 {
 121         struct diff_options opt;
 122         struct notes_merge_pair *changes;
 123         int i, len = 0;
 124
 125         trace_printf("\tdiff_tree_remote(base = %.7s, remote = %.7s)\n",
 126                oid_to_hex(base), oid_to_hex(remote));
 127
 128         diff_setup(&opt);
 129         opt.flags.recursive = 1;
 130         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 131         diff_setup_done(&opt);
 132         diff_tree_oid(base, remote, "", &opt);
 133         diffcore_std(&opt);
 134
 135         changes = xcalloc(diff_queued_diff.nr, sizeof(struct notes_merge_pair));
 136
 137         for (i = 0; i < diff_queued_diff.nr; i++) {
 138                 struct diff_filepair *p = diff_queued_diff.queue[i];
 139                 struct notes_merge_pair *mp;
 140                 int occupied;
 141                 struct object_id obj;
 142
 143                 if (verify_notes_filepair(p, &obj)) {
 144                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 145                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 146                                p->status, oid_to_hex(&p->one->oid),
 147                                oid_to_hex(&p->two->oid));
 148                         continue;
 149                 }
 150                 mp = find_notes_merge_pair_pos(changes, len, &obj, 1, &occupied);
 151                 if (occupied) {
 152                         /* We've found an addition/deletion pair */
 153                         assert(!oidcmp(&mp->obj, &obj));
 154                         if (is_null_oid(&p->one->oid)) { /* addition */
 155                                 assert(is_null_oid(&mp->remote));
 156                                 oidcpy(&mp->remote, &p->two->oid);
 157                         } else if (is_null_oid(&p->two->oid)) { /* deletion */
 158                                 assert(is_null_oid(&mp->base));
 159                                 oidcpy(&mp->base, &p->one->oid);
 160                         } else
 161                                 assert(!"Invalid existing change recorded");
 162                 } else {
 163                         oidcpy(&mp->obj, &obj);
 164                         oidcpy(&mp->base, &p->one->oid);
 165                         oidcpy(&mp->local, &uninitialized);
 166                         oidcpy(&mp->remote, &p->two->oid);
 167                         len++;
 168                 }
 169                 trace_printf("\t\tStored remote change for %s: %.7s -> %.7s\n",
 170                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
 171                        oid_to_hex(&mp->remote));
 172         }
 173         diff_flush(&opt);
 174         clear_pathspec(&opt.pathspec);
 175
 176         *num_changes = len;
 177         return changes;
 178 }
 179
 180 static void diff_tree_local(struct notes_merge_options *o,
 181                             struct notes_merge_pair *changes, int len,
 182                             const struct object_id *base,
 183                             const struct object_id *local)
 184 {
 185         struct diff_options opt;
 186         int i;
 187
 188         trace_printf("\tdiff_tree_local(len = %i, base = %.7s, local = %.7s)\n",
 189                len, oid_to_hex(base), oid_to_hex(local));
 190
 191         diff_setup(&opt);
 192         opt.flags.recursive = 1;
 193         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 194         diff_setup_done(&opt);
 195         diff_tree_oid(base, local, "", &opt);
 196         diffcore_std(&opt);
 197
 198         for (i = 0; i < diff_queued_diff.nr; i++) {
 199                 struct diff_filepair *p = diff_queued_diff.queue[i];
 200                 struct notes_merge_pair *mp;
 201                 int match;
 202                 struct object_id obj;
 203
 204                 if (verify_notes_filepair(p, &obj)) {
 205                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 206                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 207                                p->status, oid_to_hex(&p->one->oid),
 208                                oid_to_hex(&p->two->oid));
 209                         continue;
 210                 }
 211                 mp = find_notes_merge_pair_pos(changes, len, &obj, 0, &match);
 212                 if (!match) {
 213                         trace_printf("\t\tIgnoring local-only change for %s: "
 214                                "%.7s -> %.7s\n", oid_to_hex(&obj),
 215                                oid_to_hex(&p->one->oid),
 216                                oid_to_hex(&p->two->oid));
 217                         continue;
 218                 }
 219
 220                 assert(!oidcmp(&mp->obj, &obj));
 221                 if (is_null_oid(&p->two->oid)) { /* deletion */
 222                         /*
 223                          * Either this is a true deletion (1), or it is part
 224                          * of an A/D pair (2), or D/A pair (3):
 225                          *
 226                          * (1) mp->local is uninitialized; set it to null_sha1
 227                          * (2) mp->local is not uninitialized; don't touch it
 228                          * (3) mp->local is uninitialized; set it to null_sha1
 229                          *     (will be overwritten by following addition)
 230                          */
 231                         if (!oidcmp(&mp->local, &uninitialized))
 232                                 oidclr(&mp->local);
 233                 } else if (is_null_oid(&p->one->oid)) { /* addition */
 234                         /*
 235                          * Either this is a true addition (1), or it is part
 236                          * of an A/D pair (2), or D/A pair (3):
 237                          *
 238                          * (1) mp->local is uninitialized; set to p->two->sha1
 239                          * (2) mp->local is uninitialized; set to p->two->sha1
 240                          * (3) mp->local is null_sha1;     set to p->two->sha1
 241                          */
 242                         assert(is_null_oid(&mp->local) ||
 243                                !oidcmp(&mp->local, &uninitialized));
 244                         oidcpy(&mp->local, &p->two->oid);
 245                 } else { /* modification */
 246                         /*
 247                          * This is a true modification. p->one->sha1 shall
 248                          * match mp->base, and mp->local shall be uninitialized.
 249                          * Set mp->local to p->two->sha1.
 250                          */
 251                         assert(!oidcmp(&p->one->oid, &mp->base));
 252                         assert(!oidcmp(&mp->local, &uninitialized));
 253                         oidcpy(&mp->local, &p->two->oid);
 254                 }
 255                 trace_printf("\t\tStored local change for %s: %.7s -> %.7s\n",
 256                        oid_to_hex(&mp->obj), oid_to_hex(&mp->base),
 257                        oid_to_hex(&mp->local));
 258         }
 259         diff_flush(&opt);
 260         clear_pathspec(&opt.pathspec);
 261 }
 262
 263 static void check_notes_merge_worktree(struct notes_merge_options *o)
 264 {
 265         if (!o->has_worktree) {
 266                 /*
 267                  * Must establish NOTES_MERGE_WORKTREE.
 268                  * Abort if NOTES_MERGE_WORKTREE already exists
 269                  */
 270                 if (file_exists(git_path(NOTES_MERGE_WORKTREE)) &&
 271                     !is_empty_dir(git_path(NOTES_MERGE_WORKTREE))) {
 272                         if (advice_resolve_conflict)
 273                                 die(_("You have not concluded your previous "
 274                                     "notes merge (%s exists).\nPlease, use "
 275                                     "'git notes merge --commit' or 'git notes "
 276                                     "merge --abort' to commit/abort the "
 277                                     "previous merge before you start a new "
 278                                     "notes merge."), git_path("NOTES_MERGE_*"));
 279                         else
 280                                 die(_("You have not concluded your notes merge "
 281                                     "(%s exists)."), git_path("NOTES_MERGE_*"));
 282                 }
 283
 284                 if (safe_create_leading_directories_const(git_path(
 285                                 NOTES_MERGE_WORKTREE "/.test")))
 286                         die_errno("unable to create directory %s",
 287                                   git_path(NOTES_MERGE_WORKTREE));
 288                 o->has_worktree = 1;
 289         } else if (!file_exists(git_path(NOTES_MERGE_WORKTREE)))
 290                 /* NOTES_MERGE_WORKTREE should already be established */
 291                 die("missing '%s'. This should not happen",
 292                     git_path(NOTES_MERGE_WORKTREE));
 293 }
 294
 295 static void write_buf_to_worktree(const struct object_id *obj,
 296                                   const char *buf, unsigned long size)
 297 {
 298         int fd;
 299         char *path = git_pathdup(NOTES_MERGE_WORKTREE "/%s", oid_to_hex(obj));
 300         if (safe_create_leading_directories_const(path))
 301                 die_errno("unable to create directory for '%s'", path);
 302
 303         fd = xopen(path, O_WRONLY | O_EXCL | O_CREAT, 0666);
 304
 305         while (size > 0) {
 306                 ssize_t ret = write_in_full(fd, buf, size);
 307                 if (ret < 0) {
 308                         /* Ignore epipe */
 309                         if (errno == EPIPE)
 310                                 break;
 311                         die_errno("notes-merge");
 312                 }
 313                 size -= ret;
 314                 buf += ret;
 315         }
 316
 317         close(fd);
 318         free(path);
 319 }
 320
 321 static void write_note_to_worktree(const struct object_id *obj,
 322                                    const struct object_id *note)
 323 {
 324         enum object_type type;
 325         unsigned long size;
 326         void *buf = read_object_file(note, &type, &size);
 327
 328         if (!buf)
 329                 die("cannot read note %s for object %s",
 330                     oid_to_hex(note), oid_to_hex(obj));
 331         if (type != OBJ_BLOB)
 332                 die("blob expected in note %s for object %s",
 333                     oid_to_hex(note), oid_to_hex(obj));
 334         write_buf_to_worktree(obj, buf, size);
 335         free(buf);
 336 }
 337
 338 static int ll_merge_in_worktree(struct notes_merge_options *o,
 339                                 struct notes_merge_pair *p)
 340 {
 341         mmbuffer_t result_buf;
 342         mmfile_t base, local, remote;
 343         int status;
 344
 345         read_mmblob(&base, &p->base);
 346         read_mmblob(&local, &p->local);
 347         read_mmblob(&remote, &p->remote);
 348
 349         status = ll_merge(&result_buf, oid_to_hex(&p->obj), &base, NULL,
 350                           &local, o->local_ref, &remote, o->remote_ref, NULL);
 351
 352         free(base.ptr);
 353         free(local.ptr);
 354         free(remote.ptr);
 355
 356         if ((status < 0) || !result_buf.ptr)
 357                 die("Failed to execute internal merge");
 358
 359         write_buf_to_worktree(&p->obj, result_buf.ptr, result_buf.size);
 360         free(result_buf.ptr);
 361
 362         return status;
 363 }
 364
 365 static int merge_one_change_manual(struct notes_merge_options *o,
 366                                    struct notes_merge_pair *p,
 367                                    struct notes_tree *t)
 368 {
 369         const char *lref = o->local_ref ? o->local_ref : "local version";
 370         const char *rref = o->remote_ref ? o->remote_ref : "remote version";
 371
 372         trace_printf("\t\t\tmerge_one_change_manual(obj = %.7s, base = %.7s, "
 373                "local = %.7s, remote = %.7s)\n",
 374                oid_to_hex(&p->obj), oid_to_hex(&p->base),
 375                oid_to_hex(&p->local), oid_to_hex(&p->remote));
 376
 377         /* add "Conflicts:" section to commit message first time through */
 378         if (!o->has_worktree)
 379                 strbuf_addstr(&(o->commit_msg), "\n\nConflicts:\n");
 380
 381         strbuf_addf(&(o->commit_msg), "\t%s\n", oid_to_hex(&p->obj));
 382
 383         if (o->verbosity >= 2)
 384                 printf("Auto-merging notes for %s\n", oid_to_hex(&p->obj));
 385         check_notes_merge_worktree(o);
 386         if (is_null_oid(&p->local)) {
 387                 /* D/F conflict, checkout p->remote */
 388                 assert(!is_null_oid(&p->remote));
 389                 if (o->verbosity >= 1)
 390                         printf("CONFLICT (delete/modify): Notes for object %s "
 391                                 "deleted in %s and modified in %s. Version from %s "
 392                                 "left in tree.\n",
 393                                 oid_to_hex(&p->obj), lref, rref, rref);
 394                 write_note_to_worktree(&p->obj, &p->remote);
 395         } else if (is_null_oid(&p->remote)) {
 396                 /* D/F conflict, checkout p->local */
 397                 assert(!is_null_oid(&p->local));
 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), rref, lref, lref);
 403                 write_note_to_worktree(&p->obj, &p->local);
 404         } else {
 405                 /* "regular" conflict, checkout result of ll_merge() */
 406                 const char *reason = "content";
 407                 if (is_null_oid(&p->base))
 408                         reason = "add/add";
 409                 assert(!is_null_oid(&p->local));
 410                 assert(!is_null_oid(&p->remote));
 411                 if (o->verbosity >= 1)
 412                         printf("CONFLICT (%s): Merge conflict in notes for "
 413                                 "object %s\n", reason,
 414                                 oid_to_hex(&p->obj));
 415                 ll_merge_in_worktree(o, p);
 416         }
 417
 418         trace_printf("\t\t\tremoving from partial merge result\n");
 419         remove_note(t, p->obj.hash);
 420
 421         return 1;
 422 }
 423
 424 static int merge_one_change(struct notes_merge_options *o,
 425                             struct notes_merge_pair *p, struct notes_tree *t)
 426 {
 427         /*
 428          * Return 0 if change is successfully resolved (stored in notes_tree).
 429          * Return 1 is change results in a conflict (NOT stored in notes_tree,
 430          * but instead written to NOTES_MERGE_WORKTREE with conflict markers).
 431          */
 432         switch (o->strategy) {
 433         case NOTES_MERGE_RESOLVE_MANUAL:
 434                 return merge_one_change_manual(o, p, t);
 435         case NOTES_MERGE_RESOLVE_OURS:
 436                 if (o->verbosity >= 2)
 437                         printf("Using local notes for %s\n",
 438                                                 oid_to_hex(&p->obj));
 439                 /* nothing to do */
 440                 return 0;
 441         case NOTES_MERGE_RESOLVE_THEIRS:
 442                 if (o->verbosity >= 2)
 443                         printf("Using remote notes for %s\n",
 444                                                 oid_to_hex(&p->obj));
 445                 if (add_note(t, &p->obj, &p->remote, combine_notes_overwrite))
 446                         BUG("combine_notes_overwrite failed");
 447                 return 0;
 448         case NOTES_MERGE_RESOLVE_UNION:
 449                 if (o->verbosity >= 2)
 450                         printf("Concatenating local and remote notes for %s\n",
 451                                                         oid_to_hex(&p->obj));
 452                 if (add_note(t, &p->obj, &p->remote, combine_notes_concatenate))
 453                         die("failed to concatenate notes "
 454                             "(combine_notes_concatenate)");
 455                 return 0;
 456         case NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ:
 457                 if (o->verbosity >= 2)
 458                         printf("Concatenating unique lines in local and remote "
 459                                 "notes for %s\n", oid_to_hex(&p->obj));
 460                 if (add_note(t, &p->obj, &p->remote, combine_notes_cat_sort_uniq))
 461                         die("failed to concatenate notes "
 462                             "(combine_notes_cat_sort_uniq)");
 463                 return 0;
 464         }
 465         die("Unknown strategy (%i).", o->strategy);
 466 }
 467
 468 static int merge_changes(struct notes_merge_options *o,
 469                          struct notes_merge_pair *changes, int *num_changes,
 470                          struct notes_tree *t)
 471 {
 472         int i, conflicts = 0;
 473
 474         trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
 475         for (i = 0; i < *num_changes; i++) {
 476                 struct notes_merge_pair *p = changes + i;
 477                 trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
 478                        oid_to_hex(&p->obj), oid_to_hex(&p->base),
 479                        oid_to_hex(&p->local),
 480                        oid_to_hex(&p->remote));
 481
 482                 if (!oidcmp(&p->base, &p->remote)) {
 483                         /* no remote change; nothing to do */
 484                         trace_printf("\t\t\tskipping (no remote change)\n");
 485                 } else if (!oidcmp(&p->local, &p->remote)) {
 486                         /* same change in local and remote; nothing to do */
 487                         trace_printf("\t\t\tskipping (local == remote)\n");
 488                 } else if (!oidcmp(&p->local, &uninitialized) ||
 489                            !oidcmp(&p->local, &p->base)) {
 490                         /* no local change; adopt remote change */
 491                         trace_printf("\t\t\tno local change, adopted remote\n");
 492                         if (add_note(t, &p->obj, &p->remote,
 493                                      combine_notes_overwrite))
 494                                 BUG("combine_notes_overwrite failed");
 495                 } else {
 496                         /* need file-level merge between local and remote */
 497                         trace_printf("\t\t\tneed content-level merge\n");
 498                         conflicts += merge_one_change(o, p, t);
 499                 }
 500         }
 501
 502         return conflicts;
 503 }
 504
 505 static int merge_from_diffs(struct notes_merge_options *o,
 506                             const struct object_id *base,
 507                             const struct object_id *local,
 508                             const struct object_id *remote,
 509                             struct notes_tree *t)
 510 {
 511         struct notes_merge_pair *changes;
 512         int num_changes, conflicts;
 513
 514         trace_printf("\tmerge_from_diffs(base = %.7s, local = %.7s, "
 515                "remote = %.7s)\n", oid_to_hex(base), oid_to_hex(local),
 516                oid_to_hex(remote));
 517
 518         changes = diff_tree_remote(o, base, remote, &num_changes);
 519         diff_tree_local(o, changes, num_changes, base, local);
 520
 521         conflicts = merge_changes(o, changes, &num_changes, t);
 522         free(changes);
 523
 524         if (o->verbosity >= 4)
 525                 printf(t->dirty ?
 526                        "Merge result: %i unmerged notes and a dirty notes tree\n" :
 527                        "Merge result: %i unmerged notes and a clean notes tree\n",
 528                        conflicts);
 529
 530         return conflicts ? -1 : 1;
 531 }
 532
 533 int notes_merge(struct notes_merge_options *o,
 534                 struct notes_tree *local_tree,
 535                 struct object_id *result_oid)
 536 {
 537         struct object_id local_oid, remote_oid;
 538         struct commit *local, *remote;
 539         struct commit_list *bases = NULL;
 540         const struct object_id *base_oid, *base_tree_oid;
 541         int result = 0;
 542
 543         assert(o->local_ref && o->remote_ref);
 544         assert(!strcmp(o->local_ref, local_tree->ref));
 545         oidclr(result_oid);
 546
 547         trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
 548                o->local_ref, o->remote_ref);
 549
 550         /* Dereference o->local_ref into local_sha1 */
 551         if (read_ref_full(o->local_ref, 0, &local_oid, NULL))
 552                 die("Failed to resolve local notes ref '%s'", o->local_ref);
 553         else if (!check_refname_format(o->local_ref, 0) &&
 554                 is_null_oid(&local_oid))
 555                 local = NULL; /* local_oid == null_oid indicates unborn ref */
 556         else if (!(local = lookup_commit_reference(&local_oid)))
 557                 die("Could not parse local commit %s (%s)",
 558                     oid_to_hex(&local_oid), o->local_ref);
 559         trace_printf("\tlocal commit: %.7s\n", oid_to_hex(&local_oid));
 560
 561         /* Dereference o->remote_ref into remote_oid */
 562         if (get_oid(o->remote_ref, &remote_oid)) {
 563                 /*
 564                  * Failed to get remote_oid. If o->remote_ref looks like an
 565                  * unborn ref, perform the merge using an empty notes tree.
 566                  */
 567                 if (!check_refname_format(o->remote_ref, 0)) {
 568                         oidclr(&remote_oid);
 569                         remote = NULL;
 570                 } else {
 571                         die("Failed to resolve remote notes ref '%s'",
 572                             o->remote_ref);
 573                 }
 574         } else if (!(remote = lookup_commit_reference(&remote_oid))) {
 575                 die("Could not parse remote commit %s (%s)",
 576                     oid_to_hex(&remote_oid), o->remote_ref);
 577         }
 578         trace_printf("\tremote commit: %.7s\n", oid_to_hex(&remote_oid));
 579
 580         if (!local && !remote)
 581                 die("Cannot merge empty notes ref (%s) into empty notes ref "
 582                     "(%s)", o->remote_ref, o->local_ref);
 583         if (!local) {
 584                 /* result == remote commit */
 585                 oidcpy(result_oid, &remote_oid);
 586                 goto found_result;
 587         }
 588         if (!remote) {
 589                 /* result == local commit */
 590                 oidcpy(result_oid, &local_oid);
 591                 goto found_result;
 592         }
 593         assert(local && remote);
 594
 595         /* Find merge bases */
 596         bases = get_merge_bases(local, remote);
 597         if (!bases) {
 598                 base_oid = &null_oid;
 599                 base_tree_oid = the_hash_algo->empty_tree;
 600                 if (o->verbosity >= 4)
 601                         printf("No merge base found; doing history-less merge\n");
 602         } else if (!bases->next) {
 603                 base_oid = &bases->item->object.oid;
 604                 base_tree_oid = get_commit_tree_oid(bases->item);
 605                 if (o->verbosity >= 4)
 606                         printf("One merge base found (%.7s)\n",
 607                                oid_to_hex(base_oid));
 608         } else {
 609                 /* TODO: How to handle multiple merge-bases? */
 610                 base_oid = &bases->item->object.oid;
 611                 base_tree_oid = get_commit_tree_oid(bases->item);
 612                 if (o->verbosity >= 3)
 613                         printf("Multiple merge bases found. Using the first "
 614                                 "(%.7s)\n", oid_to_hex(base_oid));
 615         }
 616
 617         if (o->verbosity >= 4)
 618                 printf("Merging remote commit %.7s into local commit %.7s with "
 619                         "merge-base %.7s\n", oid_to_hex(&remote->object.oid),
 620                         oid_to_hex(&local->object.oid),
 621                         oid_to_hex(base_oid));
 622
 623         if (!oidcmp(&remote->object.oid, base_oid)) {
 624                 /* Already merged; result == local commit */
 625                 if (o->verbosity >= 2)
 626                         printf("Already up to date!\n");
 627                 oidcpy(result_oid, &local->object.oid);
 628                 goto found_result;
 629         }
 630         if (!oidcmp(&local->object.oid, base_oid)) {
 631                 /* Fast-forward; result == remote commit */
 632                 if (o->verbosity >= 2)
 633                         printf("Fast-forward\n");
 634                 oidcpy(result_oid, &remote->object.oid);
 635                 goto found_result;
 636         }
 637
 638         result = merge_from_diffs(o, base_tree_oid,
 639                                   get_commit_tree_oid(local),
 640                                   get_commit_tree_oid(remote), local_tree);
 641
 642         if (result != 0) { /* non-trivial merge (with or without conflicts) */
 643                 /* Commit (partial) result */
 644                 struct commit_list *parents = NULL;
 645                 commit_list_insert(remote, &parents); /* LIFO order */
 646                 commit_list_insert(local, &parents);
 647                 create_notes_commit(local_tree, parents, o->commit_msg.buf,
 648                                     o->commit_msg.len, result_oid);
 649         }
 650
 651 found_result:
 652         free_commit_list(bases);
 653         strbuf_release(&(o->commit_msg));
 654         trace_printf("notes_merge(): result = %i, result_oid = %.7s\n",
 655                result, oid_to_hex(result_oid));
 656         return result;
 657 }
 658
 659 int notes_merge_commit(struct notes_merge_options *o,
 660                        struct notes_tree *partial_tree,
 661                        struct commit *partial_commit,
 662                        struct object_id *result_oid)
 663 {
 664         /*
 665          * Iterate through files in .git/NOTES_MERGE_WORKTREE and add all
 666          * found notes to 'partial_tree'. Write the updated notes tree to
 667          * the DB, and commit the resulting tree object while reusing the
 668          * commit message and parents from 'partial_commit'.
 669          * Finally store the new commit object OID into 'result_oid'.
 670          */
 671         DIR *dir;
 672         struct dirent *e;
 673         struct strbuf path = STRBUF_INIT;
 674         const char *buffer = get_commit_buffer(partial_commit, NULL);
 675         const char *msg = strstr(buffer, "\n\n");
 676         int baselen;
 677
 678         git_path_buf(&path, NOTES_MERGE_WORKTREE);
 679         if (o->verbosity >= 3)
 680                 printf("Committing notes in notes merge worktree at %s\n",
 681                         path.buf);
 682
 683         if (!msg || msg[2] == '\0')
 684                 die("partial notes commit has empty message");
 685         msg += 2;
 686
 687         dir = opendir(path.buf);
 688         if (!dir)
 689                 die_errno("could not open %s", path.buf);
 690
 691         strbuf_addch(&path, '/');
 692         baselen = path.len;
 693         while ((e = readdir(dir)) != NULL) {
 694                 struct stat st;
 695                 struct object_id obj_oid, blob_oid;
 696
 697                 if (is_dot_or_dotdot(e->d_name))
 698                         continue;
 699
 700                 if (get_oid_hex(e->d_name, &obj_oid)) {
 701                         if (o->verbosity >= 3)
 702                                 printf("Skipping non-SHA1 entry '%s%s'\n",
 703                                         path.buf, e->d_name);
 704                         continue;
 705                 }
 706
 707                 strbuf_addstr(&path, e->d_name);
 708                 /* write file as blob, and add to partial_tree */
 709                 if (stat(path.buf, &st))
 710                         die_errno("Failed to stat '%s'", path.buf);
 711                 if (index_path(&blob_oid, path.buf, &st, HASH_WRITE_OBJECT))
 712                         die("Failed to write blob object from '%s'", path.buf);
 713                 if (add_note(partial_tree, &obj_oid, &blob_oid, NULL))
 714                         die("Failed to add resolved note '%s' to notes tree",
 715                             path.buf);
 716                 if (o->verbosity >= 4)
 717                         printf("Added resolved note for object %s: %s\n",
 718                                 oid_to_hex(&obj_oid), oid_to_hex(&blob_oid));
 719                 strbuf_setlen(&path, baselen);
 720         }
 721
 722         create_notes_commit(partial_tree, partial_commit->parents, msg,
 723                             strlen(msg), result_oid);
 724         unuse_commit_buffer(partial_commit, buffer);
 725         if (o->verbosity >= 4)
 726                 printf("Finalized notes merge commit: %s\n",
 727                         oid_to_hex(result_oid));
 728         strbuf_release(&path);
 729         closedir(dir);
 730         return 0;
 731 }
 732
 733 int notes_merge_abort(struct notes_merge_options *o)
 734 {
 735         /*
 736          * Remove all files within .git/NOTES_MERGE_WORKTREE. We do not remove
 737          * the .git/NOTES_MERGE_WORKTREE directory itself, since it might be
 738          * the current working directory of the user.
 739          */
 740         struct strbuf buf = STRBUF_INIT;
 741         int ret;
 742
 743         git_path_buf(&buf, NOTES_MERGE_WORKTREE);
 744         if (o->verbosity >= 3)
 745                 printf("Removing notes merge worktree at %s/*\n", buf.buf);
 746         ret = remove_dir_recursively(&buf, REMOVE_DIR_KEEP_TOPLEVEL);
 747         strbuf_release(&buf);
 748         return ret;
 749 }