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