git.oblomov.eu Git - git/blob - 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 "notes.h"
   7 #include "notes-merge.h"
   8
   9 struct notes_merge_pair {
  10         unsigned char obj[20], base[20], local[20], remote[20];
  11 };
  12
  13 void init_notes_merge_options(struct notes_merge_options *o)
  14 {
  15         memset(o, 0, sizeof(struct notes_merge_options));
  16         o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
  17 }
  18
  19 #define OUTPUT(o, v, ...) \
  20         do { \
  21                 if ((o)->verbosity >= (v)) { \
  22                         printf(__VA_ARGS__); \
  23                         puts(""); \
  24                 } \
  25         } while (0)
  26
  27 static int path_to_sha1(const char *path, unsigned char *sha1)
  28 {
  29         char hex_sha1[40];
  30         int i = 0;
  31         while (*path && i < 40) {
  32                 if (*path != '/')
  33                         hex_sha1[i++] = *path;
  34                 path++;
  35         }
  36         if (*path || i != 40)
  37                 return -1;
  38         return get_sha1_hex(hex_sha1, sha1);
  39 }
  40
  41 static int verify_notes_filepair(struct diff_filepair *p, unsigned char *sha1)
  42 {
  43         switch (p->status) {
  44         case DIFF_STATUS_MODIFIED:
  45                 assert(p->one->mode == p->two->mode);
  46                 assert(!is_null_sha1(p->one->sha1));
  47                 assert(!is_null_sha1(p->two->sha1));
  48                 break;
  49         case DIFF_STATUS_ADDED:
  50                 assert(is_null_sha1(p->one->sha1));
  51                 break;
  52         case DIFF_STATUS_DELETED:
  53                 assert(is_null_sha1(p->two->sha1));
  54                 break;
  55         default:
  56                 return -1;
  57         }
  58         assert(!strcmp(p->one->path, p->two->path));
  59         return path_to_sha1(p->one->path, sha1);
  60 }
  61
  62 static struct notes_merge_pair *find_notes_merge_pair_pos(
  63                 struct notes_merge_pair *list, int len, unsigned char *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 = hashcmp(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                         memmove(list + i + 1, list + i,
 105                                 (len - i) * sizeof(struct notes_merge_pair));
 106                         memset(list + i, 0, sizeof(struct notes_merge_pair));
 107                 }
 108         }
 109         last_index = i;
 110         return list + i;
 111 }
 112
 113 static unsigned char uninitialized[20] =
 114         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" \
 115         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff";
 116
 117 static struct notes_merge_pair *diff_tree_remote(struct notes_merge_options *o,
 118                                                  const unsigned char *base,
 119                                                  const unsigned char *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                sha1_to_hex(base), sha1_to_hex(remote));
 128
 129         diff_setup(&opt);
 130         DIFF_OPT_SET(&opt, RECURSIVE);
 131         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 132         if (diff_setup_done(&opt) < 0)
 133                 die("diff_setup_done failed");
 134         diff_tree_sha1(base, remote, "", &opt);
 135         diffcore_std(&opt);
 136
 137         changes = xcalloc(diff_queued_diff.nr, sizeof(struct notes_merge_pair));
 138
 139         for (i = 0; i < diff_queued_diff.nr; i++) {
 140                 struct diff_filepair *p = diff_queued_diff.queue[i];
 141                 struct notes_merge_pair *mp;
 142                 int occupied;
 143                 unsigned char obj[20];
 144
 145                 if (verify_notes_filepair(p, obj)) {
 146                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 147                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 148                                p->status, sha1_to_hex(p->one->sha1),
 149                                sha1_to_hex(p->two->sha1));
 150                         continue;
 151                 }
 152                 mp = find_notes_merge_pair_pos(changes, len, obj, 1, &occupied);
 153                 if (occupied) {
 154                         /* We've found an addition/deletion pair */
 155                         assert(!hashcmp(mp->obj, obj));
 156                         if (is_null_sha1(p->one->sha1)) { /* addition */
 157                                 assert(is_null_sha1(mp->remote));
 158                                 hashcpy(mp->remote, p->two->sha1);
 159                         } else if (is_null_sha1(p->two->sha1)) { /* deletion */
 160                                 assert(is_null_sha1(mp->base));
 161                                 hashcpy(mp->base, p->one->sha1);
 162                         } else
 163                                 assert(!"Invalid existing change recorded");
 164                 } else {
 165                         hashcpy(mp->obj, obj);
 166                         hashcpy(mp->base, p->one->sha1);
 167                         hashcpy(mp->local, uninitialized);
 168                         hashcpy(mp->remote, p->two->sha1);
 169                         len++;
 170                 }
 171                 trace_printf("\t\tStored remote change for %s: %.7s -> %.7s\n",
 172                        sha1_to_hex(mp->obj), sha1_to_hex(mp->base),
 173                        sha1_to_hex(mp->remote));
 174         }
 175         diff_flush(&opt);
 176         diff_tree_release_paths(&opt);
 177
 178         *num_changes = len;
 179         return changes;
 180 }
 181
 182 static void diff_tree_local(struct notes_merge_options *o,
 183                             struct notes_merge_pair *changes, int len,
 184                             const unsigned char *base,
 185                             const unsigned char *local)
 186 {
 187         struct diff_options opt;
 188         int i;
 189
 190         trace_printf("\tdiff_tree_local(len = %i, base = %.7s, local = %.7s)\n",
 191                len, sha1_to_hex(base), sha1_to_hex(local));
 192
 193         diff_setup(&opt);
 194         DIFF_OPT_SET(&opt, RECURSIVE);
 195         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 196         if (diff_setup_done(&opt) < 0)
 197                 die("diff_setup_done failed");
 198         diff_tree_sha1(base, local, "", &opt);
 199         diffcore_std(&opt);
 200
 201         for (i = 0; i < diff_queued_diff.nr; i++) {
 202                 struct diff_filepair *p = diff_queued_diff.queue[i];
 203                 struct notes_merge_pair *mp;
 204                 int match;
 205                 unsigned char obj[20];
 206
 207                 if (verify_notes_filepair(p, obj)) {
 208                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 209                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 210                                p->status, sha1_to_hex(p->one->sha1),
 211                                sha1_to_hex(p->two->sha1));
 212                         continue;
 213                 }
 214                 mp = find_notes_merge_pair_pos(changes, len, obj, 0, &match);
 215                 if (!match) {
 216                         trace_printf("\t\tIgnoring local-only change for %s: "
 217                                "%.7s -> %.7s\n", sha1_to_hex(obj),
 218                                sha1_to_hex(p->one->sha1),
 219                                sha1_to_hex(p->two->sha1));
 220                         continue;
 221                 }
 222
 223                 assert(!hashcmp(mp->obj, obj));
 224                 if (is_null_sha1(p->two->sha1)) { /* deletion */
 225                         /*
 226                          * Either this is a true deletion (1), or it is part
 227                          * of an A/D pair (2), or D/A pair (3):
 228                          *
 229                          * (1) mp->local is uninitialized; set it to null_sha1
 230                          * (2) mp->local is not uninitialized; don't touch it
 231                          * (3) mp->local is uninitialized; set it to null_sha1
 232                          *     (will be overwritten by following addition)
 233                          */
 234                         if (!hashcmp(mp->local, uninitialized))
 235                                 hashclr(mp->local);
 236                 } else if (is_null_sha1(p->one->sha1)) { /* addition */
 237                         /*
 238                          * Either this is a true addition (1), or it is part
 239                          * of an A/D pair (2), or D/A pair (3):
 240                          *
 241                          * (1) mp->local is uninitialized; set to p->two->sha1
 242                          * (2) mp->local is uninitialized; set to p->two->sha1
 243                          * (3) mp->local is null_sha1;     set to p->two->sha1
 244                          */
 245                         assert(is_null_sha1(mp->local) ||
 246                                !hashcmp(mp->local, uninitialized));
 247                         hashcpy(mp->local, p->two->sha1);
 248                 } else { /* modification */
 249                         /*
 250                          * This is a true modification. p->one->sha1 shall
 251                          * match mp->base, and mp->local shall be uninitialized.
 252                          * Set mp->local to p->two->sha1.
 253                          */
 254                         assert(!hashcmp(p->one->sha1, mp->base));
 255                         assert(!hashcmp(mp->local, uninitialized));
 256                         hashcpy(mp->local, p->two->sha1);
 257                 }
 258                 trace_printf("\t\tStored local change for %s: %.7s -> %.7s\n",
 259                        sha1_to_hex(mp->obj), sha1_to_hex(mp->base),
 260                        sha1_to_hex(mp->local));
 261         }
 262         diff_flush(&opt);
 263         diff_tree_release_paths(&opt);
 264 }
 265
 266 static int merge_one_change(struct notes_merge_options *o,
 267                             struct notes_merge_pair *p, struct notes_tree *t)
 268 {
 269         /*
 270          * Return 0 if change was resolved (and added to notes_tree),
 271          * 1 if conflict
 272          */
 273         switch (o->strategy) {
 274         case NOTES_MERGE_RESOLVE_MANUAL:
 275                 return 1;
 276         case NOTES_MERGE_RESOLVE_OURS:
 277                 OUTPUT(o, 2, "Using local notes for %s", sha1_to_hex(p->obj));
 278                 /* nothing to do */
 279                 return 0;
 280         case NOTES_MERGE_RESOLVE_THEIRS:
 281                 OUTPUT(o, 2, "Using remote notes for %s", sha1_to_hex(p->obj));
 282                 if (add_note(t, p->obj, p->remote, combine_notes_overwrite))
 283                         die("BUG: combine_notes_overwrite failed");
 284                 return 0;
 285         case NOTES_MERGE_RESOLVE_UNION:
 286                 OUTPUT(o, 2, "Concatenating local and remote notes for %s",
 287                        sha1_to_hex(p->obj));
 288                 if (add_note(t, p->obj, p->remote, combine_notes_concatenate))
 289                         die("failed to concatenate notes "
 290                             "(combine_notes_concatenate)");
 291                 return 0;
 292         }
 293         die("Unknown strategy (%i).", o->strategy);
 294 }
 295
 296 static int merge_changes(struct notes_merge_options *o,
 297                          struct notes_merge_pair *changes, int *num_changes,
 298                          struct notes_tree *t)
 299 {
 300         int i, conflicts = 0;
 301
 302         trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
 303         for (i = 0; i < *num_changes; i++) {
 304                 struct notes_merge_pair *p = changes + i;
 305                 trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
 306                        sha1_to_hex(p->obj), sha1_to_hex(p->base),
 307                        sha1_to_hex(p->local), sha1_to_hex(p->remote));
 308
 309                 if (!hashcmp(p->base, p->remote)) {
 310                         /* no remote change; nothing to do */
 311                         trace_printf("\t\t\tskipping (no remote change)\n");
 312                 } else if (!hashcmp(p->local, p->remote)) {
 313                         /* same change in local and remote; nothing to do */
 314                         trace_printf("\t\t\tskipping (local == remote)\n");
 315                 } else if (!hashcmp(p->local, uninitialized) ||
 316                            !hashcmp(p->local, p->base)) {
 317                         /* no local change; adopt remote change */
 318                         trace_printf("\t\t\tno local change, adopted remote\n");
 319                         if (add_note(t, p->obj, p->remote,
 320                                      combine_notes_overwrite))
 321                                 die("BUG: combine_notes_overwrite failed");
 322                 } else {
 323                         /* need file-level merge between local and remote */
 324                         trace_printf("\t\t\tneed content-level merge\n");
 325                         conflicts += merge_one_change(o, p, t);
 326                 }
 327         }
 328
 329         return conflicts;
 330 }
 331
 332 static int merge_from_diffs(struct notes_merge_options *o,
 333                             const unsigned char *base,
 334                             const unsigned char *local,
 335                             const unsigned char *remote, struct notes_tree *t)
 336 {
 337         struct notes_merge_pair *changes;
 338         int num_changes, conflicts;
 339
 340         trace_printf("\tmerge_from_diffs(base = %.7s, local = %.7s, "
 341                "remote = %.7s)\n", sha1_to_hex(base), sha1_to_hex(local),
 342                sha1_to_hex(remote));
 343
 344         changes = diff_tree_remote(o, base, remote, &num_changes);
 345         diff_tree_local(o, changes, num_changes, base, local);
 346
 347         conflicts = merge_changes(o, changes, &num_changes, t);
 348         free(changes);
 349
 350         OUTPUT(o, 4, "Merge result: %i unmerged notes and a %s notes tree",
 351                conflicts, t->dirty ? "dirty" : "clean");
 352
 353         return conflicts ? -1 : 1;
 354 }
 355
 356 void create_notes_commit(struct notes_tree *t, struct commit_list *parents,
 357                          const char *msg, unsigned char *result_sha1)
 358 {
 359         unsigned char tree_sha1[20];
 360
 361         assert(t->initialized);
 362
 363         if (write_notes_tree(t, tree_sha1))
 364                 die("Failed to write notes tree to database");
 365
 366         if (!parents) {
 367                 /* Deduce parent commit from t->ref */
 368                 unsigned char parent_sha1[20];
 369                 if (!read_ref(t->ref, parent_sha1)) {
 370                         struct commit *parent = lookup_commit(parent_sha1);
 371                         if (!parent || parse_commit(parent))
 372                                 die("Failed to find/parse commit %s", t->ref);
 373                         commit_list_insert(parent, &parents);
 374                 }
 375                 /* else: t->ref points to nothing, assume root/orphan commit */
 376         }
 377
 378         if (commit_tree(msg, tree_sha1, parents, result_sha1, NULL))
 379                 die("Failed to commit notes tree to database");
 380 }
 381
 382 int notes_merge(struct notes_merge_options *o,
 383                 struct notes_tree *local_tree,
 384                 unsigned char *result_sha1)
 385 {
 386         unsigned char local_sha1[20], remote_sha1[20];
 387         struct commit *local, *remote;
 388         struct commit_list *bases = NULL;
 389         const unsigned char *base_sha1, *base_tree_sha1;
 390         int result = 0;
 391
 392         assert(o->local_ref && o->remote_ref);
 393         assert(!strcmp(o->local_ref, local_tree->ref));
 394         hashclr(result_sha1);
 395
 396         trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
 397                o->local_ref, o->remote_ref);
 398
 399         /* Dereference o->local_ref into local_sha1 */
 400         if (!resolve_ref(o->local_ref, local_sha1, 0, NULL))
 401                 die("Failed to resolve local notes ref '%s'", o->local_ref);
 402         else if (!check_ref_format(o->local_ref) && is_null_sha1(local_sha1))
 403                 local = NULL; /* local_sha1 == null_sha1 indicates unborn ref */
 404         else if (!(local = lookup_commit_reference(local_sha1)))
 405                 die("Could not parse local commit %s (%s)",
 406                     sha1_to_hex(local_sha1), o->local_ref);
 407         trace_printf("\tlocal commit: %.7s\n", sha1_to_hex(local_sha1));
 408
 409         /* Dereference o->remote_ref into remote_sha1 */
 410         if (get_sha1(o->remote_ref, remote_sha1)) {
 411                 /*
 412                  * Failed to get remote_sha1. If o->remote_ref looks like an
 413                  * unborn ref, perform the merge using an empty notes tree.
 414                  */
 415                 if (!check_ref_format(o->remote_ref)) {
 416                         hashclr(remote_sha1);
 417                         remote = NULL;
 418                 } else {
 419                         die("Failed to resolve remote notes ref '%s'",
 420                             o->remote_ref);
 421                 }
 422         } else if (!(remote = lookup_commit_reference(remote_sha1))) {
 423                 die("Could not parse remote commit %s (%s)",
 424                     sha1_to_hex(remote_sha1), o->remote_ref);
 425         }
 426         trace_printf("\tremote commit: %.7s\n", sha1_to_hex(remote_sha1));
 427
 428         if (!local && !remote)
 429                 die("Cannot merge empty notes ref (%s) into empty notes ref "
 430                     "(%s)", o->remote_ref, o->local_ref);
 431         if (!local) {
 432                 /* result == remote commit */
 433                 hashcpy(result_sha1, remote_sha1);
 434                 goto found_result;
 435         }
 436         if (!remote) {
 437                 /* result == local commit */
 438                 hashcpy(result_sha1, local_sha1);
 439                 goto found_result;
 440         }
 441         assert(local && remote);
 442
 443         /* Find merge bases */
 444         bases = get_merge_bases(local, remote, 1);
 445         if (!bases) {
 446                 base_sha1 = null_sha1;
 447                 base_tree_sha1 = (unsigned char *)EMPTY_TREE_SHA1_BIN;
 448                 OUTPUT(o, 4, "No merge base found; doing history-less merge");
 449         } else if (!bases->next) {
 450                 base_sha1 = bases->item->object.sha1;
 451                 base_tree_sha1 = bases->item->tree->object.sha1;
 452                 OUTPUT(o, 4, "One merge base found (%.7s)",
 453                        sha1_to_hex(base_sha1));
 454         } else {
 455                 /* TODO: How to handle multiple merge-bases? */
 456                 base_sha1 = bases->item->object.sha1;
 457                 base_tree_sha1 = bases->item->tree->object.sha1;
 458                 OUTPUT(o, 3, "Multiple merge bases found. Using the first "
 459                        "(%.7s)", sha1_to_hex(base_sha1));
 460         }
 461
 462         OUTPUT(o, 4, "Merging remote commit %.7s into local commit %.7s with "
 463                "merge-base %.7s", sha1_to_hex(remote->object.sha1),
 464                sha1_to_hex(local->object.sha1), sha1_to_hex(base_sha1));
 465
 466         if (!hashcmp(remote->object.sha1, base_sha1)) {
 467                 /* Already merged; result == local commit */
 468                 OUTPUT(o, 2, "Already up-to-date!");
 469                 hashcpy(result_sha1, local->object.sha1);
 470                 goto found_result;
 471         }
 472         if (!hashcmp(local->object.sha1, base_sha1)) {
 473                 /* Fast-forward; result == remote commit */
 474                 OUTPUT(o, 2, "Fast-forward");
 475                 hashcpy(result_sha1, remote->object.sha1);
 476                 goto found_result;
 477         }
 478
 479         result = merge_from_diffs(o, base_tree_sha1, local->tree->object.sha1,
 480                                   remote->tree->object.sha1, local_tree);
 481
 482         if (result > 0) { /* successful non-trivial merge */
 483                 /* Commit result */
 484                 struct commit_list *parents = NULL;
 485                 commit_list_insert(remote, &parents); /* LIFO order */
 486                 commit_list_insert(local, &parents);
 487                 create_notes_commit(local_tree, parents, o->commit_msg,
 488                                     result_sha1);
 489         }
 490
 491 found_result:
 492         free_commit_list(bases);
 493         trace_printf("notes_merge(): result = %i, result_sha1 = %.7s\n",
 494                result, sha1_to_hex(result_sha1));
 495         return result;
 496 }