builtin/merge-tree.c

   1 #define USE_THE_INDEX_VARIABLE
   2 #include "builtin.h"
   3 #include "tree-walk.h"
   4 #include "xdiff-interface.h"
   5 #include "help.h"
   6 #include "gettext.h"
   7 #include "hex.h"
   8 #include "commit.h"
   9 #include "commit-reach.h"
  10 #include "merge-ort.h"
  11 #include "object-name.h"
  12 #include "object-store.h"
  13 #include "parse-options.h"
  14 #include "repository.h"
  15 #include "blob.h"
  16 #include "exec-cmd.h"
  17 #include "merge-blobs.h"
  18 #include "quote.h"
  19
  20 static int line_termination = '\n';
  21
  22 struct merge_list {
  23         struct merge_list *next;
  24         struct merge_list *link;        /* other stages for this object */
  25
  26         unsigned int stage : 2;
  27         unsigned int mode;
  28         const char *path;
  29         struct blob *blob;
  30 };
  31
  32 static struct merge_list *merge_result, **merge_result_end = &merge_result;
  33
  34 static void add_merge_entry(struct merge_list *entry)
  35 {
  36         *merge_result_end = entry;
  37         merge_result_end = &entry->next;
  38 }
  39
  40 static void trivial_merge_trees(struct tree_desc t[3], const char *base);
  41
  42 static const char *explanation(struct merge_list *entry)
  43 {
  44         switch (entry->stage) {
  45         case 0:
  46                 return "merged";
  47         case 3:
  48                 return "added in remote";
  49         case 2:
  50                 if (entry->link)
  51                         return "added in both";
  52                 return "added in local";
  53         }
  54
  55         /* Existed in base */
  56         entry = entry->link;
  57         if (!entry)
  58                 return "removed in both";
  59
  60         if (entry->link)
  61                 return "changed in both";
  62
  63         if (entry->stage == 3)
  64                 return "removed in local";
  65         return "removed in remote";
  66 }
  67
  68 static void *result(struct merge_list *entry, unsigned long *size)
  69 {
  70         enum object_type type;
  71         struct blob *base, *our, *their;
  72         const char *path = entry->path;
  73
  74         if (!entry->stage)
  75                 return repo_read_object_file(the_repository,
  76                                              &entry->blob->object.oid, &type,
  77                                              size);
  78         base = NULL;
  79         if (entry->stage == 1) {
  80                 base = entry->blob;
  81                 entry = entry->link;
  82         }
  83         our = NULL;
  84         if (entry && entry->stage == 2) {
  85                 our = entry->blob;
  86                 entry = entry->link;
  87         }
  88         their = NULL;
  89         if (entry)
  90                 their = entry->blob;
  91         return merge_blobs(the_repository->index, path,
  92                            base, our, their, size);
  93 }
  94
  95 static void *origin(struct merge_list *entry, unsigned long *size)
  96 {
  97         enum object_type type;
  98         while (entry) {
  99                 if (entry->stage == 2)
 100                         return repo_read_object_file(the_repository,
 101                                                      &entry->blob->object.oid,
 102                                                      &type, size);
 103                 entry = entry->link;
 104         }
 105         return NULL;
 106 }
 107
 108 static int show_outf(void *priv UNUSED, mmbuffer_t *mb, int nbuf)
 109 {
 110         int i;
 111         for (i = 0; i < nbuf; i++)
 112                 printf("%.*s", (int) mb[i].size, mb[i].ptr);
 113         return 0;
 114 }
 115
 116 static void show_diff(struct merge_list *entry)
 117 {
 118         unsigned long size;
 119         mmfile_t src, dst;
 120         xpparam_t xpp;
 121         xdemitconf_t xecfg;
 122         xdemitcb_t ecb = { .out_line = show_outf };
 123
 124         memset(&xpp, 0, sizeof(xpp));
 125         xpp.flags = 0;
 126         memset(&xecfg, 0, sizeof(xecfg));
 127         xecfg.ctxlen = 3;
 128
 129         src.ptr = origin(entry, &size);
 130         if (!src.ptr)
 131                 size = 0;
 132         src.size = size;
 133         dst.ptr = result(entry, &size);
 134         if (!dst.ptr)
 135                 size = 0;
 136         dst.size = size;
 137         if (xdi_diff(&src, &dst, &xpp, &xecfg, &ecb))
 138                 die("unable to generate diff");
 139         free(src.ptr);
 140         free(dst.ptr);
 141 }
 142
 143 static void show_result_list(struct merge_list *entry)
 144 {
 145         printf("%s\n", explanation(entry));
 146         do {
 147                 struct merge_list *link = entry->link;
 148                 static const char *desc[4] = { "result", "base", "our", "their" };
 149                 printf("  %-6s %o %s %s\n", desc[entry->stage], entry->mode, oid_to_hex(&entry->blob->object.oid), entry->path);
 150                 entry = link;
 151         } while (entry);
 152 }
 153
 154 static void show_result(void)
 155 {
 156         struct merge_list *walk;
 157
 158         walk = merge_result;
 159         while (walk) {
 160                 show_result_list(walk);
 161                 show_diff(walk);
 162                 walk = walk->next;
 163         }
 164 }
 165
 166 /* An empty entry never compares same, not even to another empty entry */
 167 static int same_entry(struct name_entry *a, struct name_entry *b)
 168 {
 169         return  !is_null_oid(&a->oid) &&
 170                 !is_null_oid(&b->oid) &&
 171                 oideq(&a->oid, &b->oid) &&
 172                 a->mode == b->mode;
 173 }
 174
 175 static int both_empty(struct name_entry *a, struct name_entry *b)
 176 {
 177         return is_null_oid(&a->oid) && is_null_oid(&b->oid);
 178 }
 179
 180 static struct merge_list *create_entry(unsigned stage, unsigned mode, const struct object_id *oid, const char *path)
 181 {
 182         struct merge_list *res = xcalloc(1, sizeof(*res));
 183
 184         res->stage = stage;
 185         res->path = path;
 186         res->mode = mode;
 187         res->blob = lookup_blob(the_repository, oid);
 188         return res;
 189 }
 190
 191 static char *traverse_path(const struct traverse_info *info, const struct name_entry *n)
 192 {
 193         struct strbuf buf = STRBUF_INIT;
 194         strbuf_make_traverse_path(&buf, info, n->path, n->pathlen);
 195         return strbuf_detach(&buf, NULL);
 196 }
 197
 198 static void resolve(const struct traverse_info *info, struct name_entry *ours, struct name_entry *result)
 199 {
 200         struct merge_list *orig, *final;
 201         const char *path;
 202
 203         /* If it's already ours, don't bother showing it */
 204         if (!ours)
 205                 return;
 206
 207         path = traverse_path(info, result);
 208         orig = create_entry(2, ours->mode, &ours->oid, path);
 209         final = create_entry(0, result->mode, &result->oid, path);
 210
 211         final->link = orig;
 212
 213         add_merge_entry(final);
 214 }
 215
 216 static void unresolved_directory(const struct traverse_info *info,
 217                                  struct name_entry n[3])
 218 {
 219         struct repository *r = the_repository;
 220         char *newbase;
 221         struct name_entry *p;
 222         struct tree_desc t[3];
 223         void *buf0, *buf1, *buf2;
 224
 225         for (p = n; p < n + 3; p++) {
 226                 if (p->mode && S_ISDIR(p->mode))
 227                         break;
 228         }
 229         if (n + 3 <= p)
 230                 return; /* there is no tree here */
 231
 232         newbase = traverse_path(info, p);
 233
 234 #define ENTRY_OID(e) (((e)->mode && S_ISDIR((e)->mode)) ? &(e)->oid : NULL)
 235         buf0 = fill_tree_descriptor(r, t + 0, ENTRY_OID(n + 0));
 236         buf1 = fill_tree_descriptor(r, t + 1, ENTRY_OID(n + 1));
 237         buf2 = fill_tree_descriptor(r, t + 2, ENTRY_OID(n + 2));
 238 #undef ENTRY_OID
 239
 240         trivial_merge_trees(t, newbase);
 241
 242         free(buf0);
 243         free(buf1);
 244         free(buf2);
 245         free(newbase);
 246 }
 247
 248
 249 static struct merge_list *link_entry(unsigned stage, const struct traverse_info *info, struct name_entry *n, struct merge_list *entry)
 250 {
 251         const char *path;
 252         struct merge_list *link;
 253
 254         if (!n->mode)
 255                 return entry;
 256         if (entry)
 257                 path = entry->path;
 258         else
 259                 path = traverse_path(info, n);
 260         link = create_entry(stage, n->mode, &n->oid, path);
 261         link->link = entry;
 262         return link;
 263 }
 264
 265 static void unresolved(const struct traverse_info *info, struct name_entry n[3])
 266 {
 267         struct merge_list *entry = NULL;
 268         int i;
 269         unsigned dirmask = 0, mask = 0;
 270
 271         for (i = 0; i < 3; i++) {
 272                 mask |= (1 << i);
 273                 /*
 274                  * Treat missing entries as directories so that we return
 275                  * after unresolved_directory has handled this.
 276                  */
 277                 if (!n[i].mode || S_ISDIR(n[i].mode))
 278                         dirmask |= (1 << i);
 279         }
 280
 281         unresolved_directory(info, n);
 282
 283         if (dirmask == mask)
 284                 return;
 285
 286         if (n[2].mode && !S_ISDIR(n[2].mode))
 287                 entry = link_entry(3, info, n + 2, entry);
 288         if (n[1].mode && !S_ISDIR(n[1].mode))
 289                 entry = link_entry(2, info, n + 1, entry);
 290         if (n[0].mode && !S_ISDIR(n[0].mode))
 291                 entry = link_entry(1, info, n + 0, entry);
 292
 293         add_merge_entry(entry);
 294 }
 295
 296 /*
 297  * Merge two trees together (t[1] and t[2]), using a common base (t[0])
 298  * as the origin.
 299  *
 300  * This walks the (sorted) trees in lock-step, checking every possible
 301  * name. Note that directories automatically sort differently from other
 302  * files (see "base_name_compare"), so you'll never see file/directory
 303  * conflicts, because they won't ever compare the same.
 304  *
 305  * IOW, if a directory changes to a filename, it will automatically be
 306  * seen as the directory going away, and the filename being created.
 307  *
 308  * Think of this as a three-way diff.
 309  *
 310  * The output will be either:
 311  *  - successful merge
 312  *       "0 mode sha1 filename"
 313  *    NOTE NOTE NOTE! FIXME! We really really need to walk the index
 314  *    in parallel with this too!
 315  *
 316  *  - conflict:
 317  *      "1 mode sha1 filename"
 318  *      "2 mode sha1 filename"
 319  *      "3 mode sha1 filename"
 320  *    where not all of the 1/2/3 lines may exist, of course.
 321  *
 322  * The successful merge rules are the same as for the three-way merge
 323  * in git-read-tree.
 324  */
 325 static int threeway_callback(int n, unsigned long mask, unsigned long dirmask, struct name_entry *entry, struct traverse_info *info)
 326 {
 327         /* Same in both? */
 328         if (same_entry(entry+1, entry+2) || both_empty(entry+1, entry+2)) {
 329                 /* Modified, added or removed identically */
 330                 resolve(info, NULL, entry+1);
 331                 return mask;
 332         }
 333
 334         if (same_entry(entry+0, entry+1)) {
 335                 if (!is_null_oid(&entry[2].oid) && !S_ISDIR(entry[2].mode)) {
 336                         /* We did not touch, they modified -- take theirs */
 337                         resolve(info, entry+1, entry+2);
 338                         return mask;
 339                 }
 340                 /*
 341                  * If we did not touch a directory but they made it
 342                  * into a file, we fall through and unresolved()
 343                  * recurses down.  Likewise for the opposite case.
 344                  */
 345         }
 346
 347         if (same_entry(entry+0, entry+2) || both_empty(entry+0, entry+2)) {
 348                 /* We added, modified or removed, they did not touch -- take ours */
 349                 resolve(info, NULL, entry+1);
 350                 return mask;
 351         }
 352
 353         unresolved(info, entry);
 354         return mask;
 355 }
 356
 357 static void trivial_merge_trees(struct tree_desc t[3], const char *base)
 358 {
 359         struct traverse_info info;
 360
 361         setup_traverse_info(&info, base);
 362         info.fn = threeway_callback;
 363         traverse_trees(&the_index, 3, t, &info);
 364 }
 365
 366 static void *get_tree_descriptor(struct repository *r,
 367                                  struct tree_desc *desc,
 368                                  const char *rev)
 369 {
 370         struct object_id oid;
 371         void *buf;
 372
 373         if (repo_get_oid(r, rev, &oid))
 374                 die("unknown rev %s", rev);
 375         buf = fill_tree_descriptor(r, desc, &oid);
 376         if (!buf)
 377                 die("%s is not a tree", rev);
 378         return buf;
 379 }
 380
 381 static int trivial_merge(const char *base,
 382                          const char *branch1,
 383                          const char *branch2)
 384 {
 385         struct repository *r = the_repository;
 386         struct tree_desc t[3];
 387         void *buf1, *buf2, *buf3;
 388
 389         buf1 = get_tree_descriptor(r, t+0, base);
 390         buf2 = get_tree_descriptor(r, t+1, branch1);
 391         buf3 = get_tree_descriptor(r, t+2, branch2);
 392         trivial_merge_trees(t, "");
 393         free(buf1);
 394         free(buf2);
 395         free(buf3);
 396
 397         show_result();
 398         return 0;
 399 }
 400
 401 enum mode {
 402         MODE_UNKNOWN,
 403         MODE_TRIVIAL,
 404         MODE_REAL,
 405 };
 406
 407 struct merge_tree_options {
 408         int mode;
 409         int allow_unrelated_histories;
 410         int show_messages;
 411         int name_only;
 412         int use_stdin;
 413 };
 414
 415 static int real_merge(struct merge_tree_options *o,
 416                       const char *merge_base,
 417                       const char *branch1, const char *branch2,
 418                       const char *prefix)
 419 {
 420         struct commit *parent1, *parent2;
 421         struct commit_list *merge_bases = NULL;
 422         struct merge_options opt;
 423         struct merge_result result = { 0 };
 424         int show_messages = o->show_messages;
 425
 426         parent1 = get_merge_parent(branch1);
 427         if (!parent1)
 428                 help_unknown_ref(branch1, "merge-tree",
 429                                  _("not something we can merge"));
 430
 431         parent2 = get_merge_parent(branch2);
 432         if (!parent2)
 433                 help_unknown_ref(branch2, "merge-tree",
 434                                  _("not something we can merge"));
 435
 436         init_merge_options(&opt, the_repository);
 437
 438         opt.show_rename_progress = 0;
 439
 440         opt.branch1 = branch1;
 441         opt.branch2 = branch2;
 442
 443         if (merge_base) {
 444                 struct commit *base_commit;
 445                 struct tree *base_tree, *parent1_tree, *parent2_tree;
 446
 447                 base_commit = lookup_commit_reference_by_name(merge_base);
 448                 if (!base_commit)
 449                         die(_("could not lookup commit %s"), merge_base);
 450
 451                 opt.ancestor = merge_base;
 452                 base_tree = repo_get_commit_tree(the_repository, base_commit);
 453                 parent1_tree = repo_get_commit_tree(the_repository, parent1);
 454                 parent2_tree = repo_get_commit_tree(the_repository, parent2);
 455                 merge_incore_nonrecursive(&opt, base_tree, parent1_tree, parent2_tree, &result);
 456         } else {
 457                 /*
 458                  * Get the merge bases, in reverse order; see comment above
 459                  * merge_incore_recursive in merge-ort.h
 460                  */
 461                 merge_bases = repo_get_merge_bases(the_repository, parent1,
 462                                                    parent2);
 463                 if (!merge_bases && !o->allow_unrelated_histories)
 464                         die(_("refusing to merge unrelated histories"));
 465                 merge_bases = reverse_commit_list(merge_bases);
 466                 merge_incore_recursive(&opt, merge_bases, parent1, parent2, &result);
 467         }
 468
 469         if (result.clean < 0)
 470                 die(_("failure to merge"));
 471
 472         if (show_messages == -1)
 473                 show_messages = !result.clean;
 474
 475         if (o->use_stdin)
 476                 printf("%d%c", result.clean, line_termination);
 477         printf("%s%c", oid_to_hex(&result.tree->object.oid), line_termination);
 478         if (!result.clean) {
 479                 struct string_list conflicted_files = STRING_LIST_INIT_NODUP;
 480                 const char *last = NULL;
 481                 int i;
 482
 483                 merge_get_conflicted_files(&result, &conflicted_files);
 484                 for (i = 0; i < conflicted_files.nr; i++) {
 485                         const char *name = conflicted_files.items[i].string;
 486                         struct stage_info *c = conflicted_files.items[i].util;
 487                         if (!o->name_only)
 488                                 printf("%06o %s %d\t",
 489                                        c->mode, oid_to_hex(&c->oid), c->stage);
 490                         else if (last && !strcmp(last, name))
 491                                 continue;
 492                         write_name_quoted_relative(
 493                                 name, prefix, stdout, line_termination);
 494                         last = name;
 495                 }
 496                 string_list_clear(&conflicted_files, 1);
 497         }
 498         if (show_messages) {
 499                 putchar(line_termination);
 500                 merge_display_update_messages(&opt, line_termination == '\0',
 501                                               &result);
 502         }
 503         if (o->use_stdin)
 504                 putchar(line_termination);
 505         merge_finalize(&opt, &result);
 506         return !result.clean; /* result.clean < 0 handled above */
 507 }
 508
 509 int cmd_merge_tree(int argc, const char **argv, const char *prefix)
 510 {
 511         struct merge_tree_options o = { .show_messages = -1 };
 512         int expected_remaining_argc;
 513         int original_argc;
 514         const char *merge_base = NULL;
 515
 516         const char * const merge_tree_usage[] = {
 517                 N_("git merge-tree [--write-tree] [<options>] <branch1> <branch2>"),
 518                 N_("git merge-tree [--trivial-merge] <base-tree> <branch1> <branch2>"),
 519                 NULL
 520         };
 521         struct option mt_options[] = {
 522                 OPT_CMDMODE(0, "write-tree", &o.mode,
 523                             N_("do a real merge instead of a trivial merge"),
 524                             MODE_REAL),
 525                 OPT_CMDMODE(0, "trivial-merge", &o.mode,
 526                             N_("do a trivial merge only"), MODE_TRIVIAL),
 527                 OPT_BOOL(0, "messages", &o.show_messages,
 528                          N_("also show informational/conflict messages")),
 529                 OPT_SET_INT('z', NULL, &line_termination,
 530                             N_("separate paths with the NUL character"), '\0'),
 531                 OPT_BOOL_F(0, "name-only",
 532                            &o.name_only,
 533                            N_("list filenames without modes/oids/stages"),
 534                            PARSE_OPT_NONEG),
 535                 OPT_BOOL_F(0, "allow-unrelated-histories",
 536                            &o.allow_unrelated_histories,
 537                            N_("allow merging unrelated histories"),
 538                            PARSE_OPT_NONEG),
 539                 OPT_BOOL_F(0, "stdin",
 540                            &o.use_stdin,
 541                            N_("perform multiple merges, one per line of input"),
 542                            PARSE_OPT_NONEG),
 543                 OPT_STRING(0, "merge-base",
 544                            &merge_base,
 545                            N_("commit"),
 546                            N_("specify a merge-base for the merge")),
 547                 OPT_END()
 548         };
 549
 550         /* Parse arguments */
 551         original_argc = argc - 1; /* ignoring argv[0] */
 552         argc = parse_options(argc, argv, prefix, mt_options,
 553                              merge_tree_usage, PARSE_OPT_STOP_AT_NON_OPTION);
 554
 555         /* Handle --stdin */
 556         if (o.use_stdin) {
 557                 struct strbuf buf = STRBUF_INIT;
 558
 559                 if (o.mode == MODE_TRIVIAL)
 560                         die(_("--trivial-merge is incompatible with all other options"));
 561                 if (merge_base)
 562                         die(_("--merge-base is incompatible with --stdin"));
 563                 line_termination = '\0';
 564                 while (strbuf_getline_lf(&buf, stdin) != EOF) {
 565                         struct strbuf **split;
 566                         int result;
 567                         const char *input_merge_base = NULL;
 568
 569                         split = strbuf_split(&buf, ' ');
 570                         if (!split[0] || !split[1])
 571                                 die(_("malformed input line: '%s'."), buf.buf);
 572                         strbuf_rtrim(split[0]);
 573                         strbuf_rtrim(split[1]);
 574
 575                         /* parse the merge-base */
 576                         if (!strcmp(split[1]->buf, "--")) {
 577                                 input_merge_base = split[0]->buf;
 578                         }
 579
 580                         if (input_merge_base && split[2] && split[3] && !split[4]) {
 581                                 strbuf_rtrim(split[2]);
 582                                 strbuf_rtrim(split[3]);
 583                                 result = real_merge(&o, input_merge_base, split[2]->buf, split[3]->buf, prefix);
 584                         } else if (!input_merge_base && !split[2]) {
 585                                 result = real_merge(&o, NULL, split[0]->buf, split[1]->buf, prefix);
 586                         } else {
 587                                 die(_("malformed input line: '%s'."), buf.buf);
 588                         }
 589
 590                         if (result < 0)
 591                                 die(_("merging cannot continue; got unclean result of %d"), result);
 592                         strbuf_list_free(split);
 593                 }
 594                 strbuf_release(&buf);
 595                 return 0;
 596         }
 597
 598         /* Figure out which mode to use */
 599         switch (o.mode) {
 600         default:
 601                 BUG("unexpected command mode %d", o.mode);
 602         case MODE_UNKNOWN:
 603                 switch (argc) {
 604                 default:
 605                         usage_with_options(merge_tree_usage, mt_options);
 606                 case 2:
 607                         o.mode = MODE_REAL;
 608                         break;
 609                 case 3:
 610                         o.mode = MODE_TRIVIAL;
 611                         break;
 612                 }
 613                 expected_remaining_argc = argc;
 614                 break;
 615         case MODE_REAL:
 616                 expected_remaining_argc = 2;
 617                 break;
 618         case MODE_TRIVIAL:
 619                 expected_remaining_argc = 3;
 620                 /* Removal of `--trivial-merge` is expected */
 621                 original_argc--;
 622                 break;
 623         }
 624         if (o.mode == MODE_TRIVIAL && argc < original_argc)
 625                 die(_("--trivial-merge is incompatible with all other options"));
 626
 627         if (argc != expected_remaining_argc)
 628                 usage_with_options(merge_tree_usage, mt_options);
 629
 630         /* Do the relevant type of merge */
 631         if (o.mode == MODE_REAL)
 632                 return real_merge(&o, merge_base, argv[0], argv[1], prefix);
 633         else
 634                 return trivial_merge(argv[0], argv[1], argv[2]);
 635 }