notes-merge.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "refs.h"
   4 #include "diff.h"
   5 #include "diffcore.h"
   6 #include "xdiff-interface.h"
   7 #include "ll-merge.h"
   8 #include "dir.h"
   9 #include "notes.h"
  10 #include "notes-merge.h"
  11 #include "strbuf.h"
  12 #include "notes-utils.h"
  13
  14 struct notes_merge_pair {
  15         struct object_id obj, base, local, remote;
  16 };
  17
  18 void init_notes_merge_options(struct notes_merge_options *o)
  19 {
  20         memset(o, 0, sizeof(struct notes_merge_options));
  21         strbuf_init(&(o->commit_msg), 0);
  22         o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
  23 }
  24
  25 static int path_to_sha1(const char *path, unsigned char *sha1)
  26 {
  27         char hex_sha1[40];
  28         int i = 0;
  29         while (*path && i < 40) {
  30                 if (*path != '/')
  31                         hex_sha1[i++] = *path;
  32                 path++;
  33         }
  34         if (*path || i != 40)
  35                 return -1;
  36         return get_sha1_hex(hex_sha1, sha1);
  37 }
  38
  39 static int verify_notes_filepair(struct diff_filepair *p, unsigned char *sha1)
  40 {
  41         switch (p->status) {
  42         case DIFF_STATUS_MODIFIED:
  43                 assert(p->one->mode == p->two->mode);
  44                 assert(!is_null_oid(&p->one->oid));
  45                 assert(!is_null_oid(&p->two->oid));
  46                 break;
  47         case DIFF_STATUS_ADDED:
  48                 assert(is_null_oid(&p->one->oid));
  49                 break;
  50         case DIFF_STATUS_DELETED:
  51                 assert(is_null_oid(&p->two->oid));
  52                 break;
  53         default:
  54                 return -1;
  55         }
  56         assert(!strcmp(p->one->path, p->two->path));
  57         return path_to_sha1(p->one->path, sha1);
  58 }
  59
  60 static struct notes_merge_pair *find_notes_merge_pair_pos(
  61                 struct notes_merge_pair *list, int len, unsigned char *obj,
  62                 int insert_new, int *occupied)
  63 {
  64         /*
  65          * Both diff_tree_remote() and diff_tree_local() tend to process
  66          * merge_pairs in ascending order. Therefore, cache last returned
  67          * index, and search sequentially from there until the appropriate
  68          * position is found.
  69          *
  70          * Since inserts only happen from diff_tree_remote() (which mainly
  71          * _appends_), we don't care that inserting into the middle of the
  72          * list is expensive (using memmove()).
  73          */
  74         static int last_index;
  75         int i = last_index < len ? last_index : len - 1;
  76         int prev_cmp = 0, cmp = -1;
  77         while (i >= 0 && i < len) {
  78                 cmp = hashcmp(obj, list[i].obj.hash);
  79                 if (!cmp) /* obj belongs @ i */
  80                         break;
  81                 else if (cmp < 0 && prev_cmp <= 0) /* obj belongs < i */
  82                         i--;
  83                 else if (cmp < 0) /* obj belongs between i-1 and i */
  84                         break;
  85                 else if (cmp > 0 && prev_cmp >= 0) /* obj belongs > i */
  86                         i++;
  87                 else /* if (cmp > 0) */ { /* obj belongs between i and i+1 */
  88                         i++;
  89                         break;
  90                 }
  91                 prev_cmp = cmp;
  92         }
  93         if (i < 0)
  94                 i = 0;
  95         /* obj belongs at, or immediately preceding, index i (0 <= i <= len) */
  96
  97         if (!cmp)
  98                 *occupied = 1;
  99         else {
 100                 *occupied = 0;
 101                 if (insert_new && i < len) {
 102                         memmove(list + i + 1, list + i,
 103                                 (len - i) * sizeof(struct notes_merge_pair));
 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 unsigned char *base,
 118                                                  const unsigned char *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                sha1_to_hex(base), sha1_to_hex(remote));
 127
 128         diff_setup(&opt);
 129         DIFF_OPT_SET(&opt, RECURSIVE);
 130         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 131         diff_setup_done(&opt);
 132         diff_tree_sha1(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                 unsigned char obj[20];
 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(!hashcmp(mp->obj.hash, 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                         hashcpy(mp->obj.hash, 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 unsigned char *base,
 183                             const unsigned char *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, sha1_to_hex(base), sha1_to_hex(local));
 190
 191         diff_setup(&opt);
 192         DIFF_OPT_SET(&opt, RECURSIVE);
 193         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 194         diff_setup_done(&opt);
 195         diff_tree_sha1(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                 unsigned char obj[20];
 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", sha1_to_hex(obj),
 215                                oid_to_hex(&p->one->oid),
 216                                oid_to_hex(&p->two->oid));
 217                         continue;
 218                 }
 219
 220                 assert(!hashcmp(mp->obj.hash, 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 unsigned char *obj,
 296                                   const char *buf, unsigned long size)
 297 {
 298         int fd;
 299         char *path = git_pathdup(NOTES_MERGE_WORKTREE "/%s", sha1_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                 long 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                 } else if (!ret) {
 313                         die("notes-merge: disk full?");
 314                 }
 315                 size -= ret;
 316                 buf += ret;
 317         }
 318
 319         close(fd);
 320         free(path);
 321 }
 322
 323 static void write_note_to_worktree(const unsigned char *obj,
 324                                    const unsigned char *note)
 325 {
 326         enum object_type type;
 327         unsigned long size;
 328         void *buf = read_sha1_file(note, &type, &size);
 329
 330         if (!buf)
 331                 die("cannot read note %s for object %s",
 332                     sha1_to_hex(note), sha1_to_hex(obj));
 333         if (type != OBJ_BLOB)
 334                 die("blob expected in note %s for object %s",
 335                     sha1_to_hex(note), sha1_to_hex(obj));
 336         write_buf_to_worktree(obj, buf, size);
 337         free(buf);
 338 }
 339
 340 static int ll_merge_in_worktree(struct notes_merge_options *o,
 341                                 struct notes_merge_pair *p)
 342 {
 343         mmbuffer_t result_buf;
 344         mmfile_t base, local, remote;
 345         int status;
 346
 347         read_mmblob(&base, &p->base);
 348         read_mmblob(&local, &p->local);
 349         read_mmblob(&remote, &p->remote);
 350
 351         status = ll_merge(&result_buf, oid_to_hex(&p->obj), &base, NULL,
 352                           &local, o->local_ref, &remote, o->remote_ref, NULL);
 353
 354         free(base.ptr);
 355         free(local.ptr);
 356         free(remote.ptr);
 357
 358         if ((status < 0) || !result_buf.ptr)
 359                 die("Failed to execute internal merge");
 360
 361         write_buf_to_worktree(p->obj.hash, result_buf.ptr, result_buf.size);
 362         free(result_buf.ptr);
 363
 364         return status;
 365 }
 366
 367 static int merge_one_change_manual(struct notes_merge_options *o,
 368                                    struct notes_merge_pair *p,
 369                                    struct notes_tree *t)
 370 {
 371         const char *lref = o->local_ref ? o->local_ref : "local version";
 372         const char *rref = o->remote_ref ? o->remote_ref : "remote version";
 373
 374         trace_printf("\t\t\tmerge_one_change_manual(obj = %.7s, base = %.7s, "
 375                "local = %.7s, remote = %.7s)\n",
 376                oid_to_hex(&p->obj), oid_to_hex(&p->base),
 377                oid_to_hex(&p->local), oid_to_hex(&p->remote));
 378
 379         /* add "Conflicts:" section to commit message first time through */
 380         if (!o->has_worktree)
 381                 strbuf_addstr(&(o->commit_msg), "\n\nConflicts:\n");
 382
 383         strbuf_addf(&(o->commit_msg), "\t%s\n", oid_to_hex(&p->obj));
 384
 385         if (o->verbosity >= 2)
 386                 printf("Auto-merging notes for %s\n", oid_to_hex(&p->obj));
 387         check_notes_merge_worktree(o);
 388         if (is_null_oid(&p->local)) {
 389                 /* D/F conflict, checkout p->remote */
 390                 assert(!is_null_oid(&p->remote));
 391                 if (o->verbosity >= 1)
 392                         printf("CONFLICT (delete/modify): Notes for object %s "
 393                                 "deleted in %s and modified in %s. Version from %s "
 394                                 "left in tree.\n",
 395                                 oid_to_hex(&p->obj), lref, rref, rref);
 396                 write_note_to_worktree(p->obj.hash, p->remote.hash);
 397         } else if (is_null_oid(&p->remote)) {
 398                 /* D/F conflict, checkout p->local */
 399                 assert(!is_null_oid(&p->local));
 400                 if (o->verbosity >= 1)
 401                         printf("CONFLICT (delete/modify): Notes for object %s "
 402                                 "deleted in %s and modified in %s. Version from %s "
 403                                 "left in tree.\n",
 404                                 oid_to_hex(&p->obj), rref, lref, lref);
 405                 write_note_to_worktree(p->obj.hash, p->local.hash);
 406         } else {
 407                 /* "regular" conflict, checkout result of ll_merge() */
 408                 const char *reason = "content";
 409                 if (is_null_oid(&p->base))
 410                         reason = "add/add";
 411                 assert(!is_null_oid(&p->local));
 412                 assert(!is_null_oid(&p->remote));
 413                 if (o->verbosity >= 1)
 414                         printf("CONFLICT (%s): Merge conflict in notes for "
 415                                 "object %s\n", reason,
 416                                 oid_to_hex(&p->obj));
 417                 ll_merge_in_worktree(o, p);
 418         }
 419
 420         trace_printf("\t\t\tremoving from partial merge result\n");
 421         remove_note(t, p->obj.hash);
 422
 423         return 1;
 424 }
 425
 426 static int merge_one_change(struct notes_merge_options *o,
 427                             struct notes_merge_pair *p, struct notes_tree *t)
 428 {
 429         /*
 430          * Return 0 if change is successfully resolved (stored in notes_tree).
 431          * Return 1 is change results in a conflict (NOT stored in notes_tree,
 432          * but instead written to NOTES_MERGE_WORKTREE with conflict markers).
 433          */
 434         switch (o->strategy) {
 435         case NOTES_MERGE_RESOLVE_MANUAL:
 436                 return merge_one_change_manual(o, p, t);
 437         case NOTES_MERGE_RESOLVE_OURS:
 438                 if (o->verbosity >= 2)
 439                         printf("Using local notes for %s\n",
 440                                                 oid_to_hex(&p->obj));
 441                 /* nothing to do */
 442                 return 0;
 443         case NOTES_MERGE_RESOLVE_THEIRS:
 444                 if (o->verbosity >= 2)
 445                         printf("Using remote notes for %s\n",
 446                                                 oid_to_hex(&p->obj));
 447                 if (add_note(t, p->obj.hash, p->remote.hash, combine_notes_overwrite))
 448                         die("BUG: combine_notes_overwrite failed");
 449                 return 0;
 450         case NOTES_MERGE_RESOLVE_UNION:
 451                 if (o->verbosity >= 2)
 452                         printf("Concatenating local and remote notes for %s\n",
 453                                                         oid_to_hex(&p->obj));
 454                 if (add_note(t, p->obj.hash, p->remote.hash, combine_notes_concatenate))
 455                         die("failed to concatenate notes "
 456                             "(combine_notes_concatenate)");
 457                 return 0;
 458         case NOTES_MERGE_RESOLVE_CAT_SORT_UNIQ:
 459                 if (o->verbosity >= 2)
 460                         printf("Concatenating unique lines in local and remote "
 461                                 "notes for %s\n", oid_to_hex(&p->obj));
 462                 if (add_note(t, p->obj.hash, p->remote.hash, combine_notes_cat_sort_uniq))
 463                         die("failed to concatenate notes "
 464                             "(combine_notes_cat_sort_uniq)");
 465                 return 0;
 466         }
 467         die("Unknown strategy (%i).", o->strategy);
 468 }
 469
 470 static int merge_changes(struct notes_merge_options *o,
 471                          struct notes_merge_pair *changes, int *num_changes,
 472                          struct notes_tree *t)
 473 {
 474         int i, conflicts = 0;
 475
 476         trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
 477         for (i = 0; i < *num_changes; i++) {
 478                 struct notes_merge_pair *p = changes + i;
 479                 trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
 480                        oid_to_hex(&p->obj), oid_to_hex(&p->base),
 481                        oid_to_hex(&p->local),
 482                        oid_to_hex(&p->remote));
 483
 484                 if (!oidcmp(&p->base, &p->remote)) {
 485                         /* no remote change; nothing to do */
 486                         trace_printf("\t\t\tskipping (no remote change)\n");
 487                 } else if (!oidcmp(&p->local, &p->remote)) {
 488                         /* same change in local and remote; nothing to do */
 489                         trace_printf("\t\t\tskipping (local == remote)\n");
 490                 } else if (!oidcmp(&p->local, &uninitialized) ||
 491                            !oidcmp(&p->local, &p->base)) {
 492                         /* no local change; adopt remote change */
 493                         trace_printf("\t\t\tno local change, adopted remote\n");
 494                         if (add_note(t, p->obj.hash, p->remote.hash,
 495                                      combine_notes_overwrite))
 496                                 die("BUG: combine_notes_overwrite failed");
 497                 } else {
 498                         /* need file-level merge between local and remote */
 499                         trace_printf("\t\t\tneed content-level merge\n");
 500                         conflicts += merge_one_change(o, p, t);
 501                 }
 502         }
 503
 504         return conflicts;
 505 }
 506
 507 static int merge_from_diffs(struct notes_merge_options *o,
 508                             const unsigned char *base,
 509                             const unsigned char *local,
 510                             const unsigned char *remote, 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", sha1_to_hex(base), sha1_to_hex(local),
 517                sha1_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                 unsigned char *result_sha1)
 537 {
 538         unsigned char local_sha1[20], remote_sha1[20];
 539         struct commit *local, *remote;
 540         struct commit_list *bases = NULL;
 541         const unsigned char *base_sha1, *base_tree_sha1;
 542         int result = 0;
 543
 544         assert(o->local_ref && o->remote_ref);
 545         assert(!strcmp(o->local_ref, local_tree->ref));
 546         hashclr(result_sha1);
 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_sha1, 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_sha1(local_sha1))
 556                 local = NULL; /* local_sha1 == null_sha1 indicates unborn ref */
 557         else if (!(local = lookup_commit_reference(local_sha1)))
 558                 die("Could not parse local commit %s (%s)",
 559                     sha1_to_hex(local_sha1), o->local_ref);
 560         trace_printf("\tlocal commit: %.7s\n", sha1_to_hex(local_sha1));
 561
 562         /* Dereference o->remote_ref into remote_sha1 */
 563         if (get_sha1(o->remote_ref, remote_sha1)) {
 564                 /*
 565                  * Failed to get remote_sha1. 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                         hashclr(remote_sha1);
 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(remote_sha1))) {
 576                 die("Could not parse remote commit %s (%s)",
 577                     sha1_to_hex(remote_sha1), o->remote_ref);
 578         }
 579         trace_printf("\tremote commit: %.7s\n", sha1_to_hex(remote_sha1));
 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                 hashcpy(result_sha1, remote_sha1);
 587                 goto found_result;
 588         }
 589         if (!remote) {
 590                 /* result == local commit */
 591                 hashcpy(result_sha1, local_sha1);
 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_sha1 = null_sha1;
 600                 base_tree_sha1 = EMPTY_TREE_SHA1_BIN;
 601                 if (o->verbosity >= 4)
 602                         printf("No merge base found; doing history-less merge\n");
 603         } else if (!bases->next) {
 604                 base_sha1 = bases->item->object.oid.hash;
 605                 base_tree_sha1 = bases->item->tree->object.oid.hash;
 606                 if (o->verbosity >= 4)
 607                         printf("One merge base found (%.7s)\n",
 608                                 sha1_to_hex(base_sha1));
 609         } else {
 610                 /* TODO: How to handle multiple merge-bases? */
 611                 base_sha1 = bases->item->object.oid.hash;
 612                 base_tree_sha1 = bases->item->tree->object.oid.hash;
 613                 if (o->verbosity >= 3)
 614                         printf("Multiple merge bases found. Using the first "
 615                                 "(%.7s)\n", sha1_to_hex(base_sha1));
 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                         sha1_to_hex(base_sha1));
 623
 624         if (!hashcmp(remote->object.oid.hash, base_sha1)) {
 625                 /* Already merged; result == local commit */
 626                 if (o->verbosity >= 2)
 627                         printf("Already up-to-date!\n");
 628                 hashcpy(result_sha1, local->object.oid.hash);
 629                 goto found_result;
 630         }
 631         if (!hashcmp(local->object.oid.hash, base_sha1)) {
 632                 /* Fast-forward; result == remote commit */
 633                 if (o->verbosity >= 2)
 634                         printf("Fast-forward\n");
 635                 hashcpy(result_sha1, remote->object.oid.hash);
 636                 goto found_result;
 637         }
 638
 639         result = merge_from_diffs(o, base_tree_sha1, local->tree->object.oid.hash,
 640                                   remote->tree->object.oid.hash, 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,
 648                                     o->commit_msg.buf, o->commit_msg.len,
 649                                     result_sha1);
 650         }
 651
 652 found_result:
 653         free_commit_list(bases);
 654         strbuf_release(&(o->commit_msg));
 655         trace_printf("notes_merge(): result = %i, result_sha1 = %.7s\n",
 656                result, sha1_to_hex(result_sha1));
 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                        unsigned char *result_sha1)
 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 SHA1 into 'result_sha1'.
 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         strbuf_addstr(&path, git_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                 unsigned char obj_sha1[20], blob_sha1[20];
 697
 698                 if (is_dot_or_dotdot(e->d_name))
 699                         continue;
 700
 701                 if (strlen(e->d_name) != 40 || get_sha1_hex(e->d_name, obj_sha1)) {
 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_sha1, path.buf, &st, HASH_WRITE_OBJECT))
 713                         die("Failed to write blob object from '%s'", path.buf);
 714                 if (add_note(partial_tree, obj_sha1, blob_sha1, 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                                 sha1_to_hex(obj_sha1), sha1_to_hex(blob_sha1));
 720                 strbuf_setlen(&path, baselen);
 721         }
 722
 723         create_notes_commit(partial_tree, partial_commit->parents,
 724                             msg, strlen(msg), result_sha1);
 725         unuse_commit_buffer(partial_commit, buffer);
 726         if (o->verbosity >= 4)
 727                 printf("Finalized notes merge commit: %s\n",
 728                         sha1_to_hex(result_sha1));
 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         strbuf_addstr(&buf, git_path(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 }