builtin/merge-tree.c

   1 #include "builtin.h"
   2 #include "tree-walk.h"
   3 #include "xdiff-interface.h"
   4 #include "help.h"
   5 #include "gettext.h"
   6 #include "hex.h"
   7 #include "commit.h"
   8 #include "commit-reach.h"
   9 #include "merge-ort.h"
  10 #include "object-name.h"
  11 #include "object-store-ll.h"
  12 #include "parse-options.h"
  13 #include "repository.h"
  14 #include "blob.h"
  15 #include "merge-blobs.h"
  16 #include "quote.h"
  17 #include "tree.h"
  18 #include "config.h"
  19 #include "strvec.h"
  20
  21 static int line_termination = '\n';
  22
  23 struct merge_list {
  24         struct merge_list *next;
  25         struct merge_list *link;        /* other stages for this object */
  26
  27         unsigned int stage : 2;
  28         unsigned int mode;
  29         const char *path;
  30         struct blob *blob;
  31 };
  32
  33 static struct merge_list *merge_result, **merge_result_end = &merge_result;
  34
  35 static void add_merge_entry(struct merge_list *entry)
  36 {
  37         *merge_result_end = entry;
  38         merge_result_end = &entry->next;
  39 }
  40
  41 static void trivial_merge_trees(struct tree_desc t[3], const char *base);
  42
  43 static const char *explanation(struct merge_list *entry)
  44 {
  45         switch (entry->stage) {
  46         case 0:
  47                 return "merged";
  48         case 3:
  49                 return "added in remote";
  50         case 2:
  51                 if (entry->link)
  52                         return "added in both";
  53                 return "added in local";
  54         }
  55
  56         /* Existed in base */
  57         entry = entry->link;
  58         if (!entry)
  59                 return "removed in both";
  60
  61         if (entry->link)
  62                 return "changed in both";
  63
  64         if (entry->stage == 3)
  65                 return "removed in local";
  66         return "removed in remote";
  67 }
  68
  69 static void *result(struct merge_list *entry, unsigned long *size)
  70 {
  71         enum object_type type;
  72         struct blob *base, *our, *their;
  73         const char *path = entry->path;
  74
  75         if (!entry->stage)
  76                 return repo_read_object_file(the_repository,
  77                                              &entry->blob->object.oid, &type,
  78                                              size);
  79         base = NULL;
  80         if (entry->stage == 1) {
  81                 base = entry->blob;
  82                 entry = entry->link;
  83         }
  84         our = NULL;
  85         if (entry && entry->stage == 2) {
  86                 our = entry->blob;
  87                 entry = entry->link;
  88         }
  89         their = NULL;
  90         if (entry)
  91                 their = entry->blob;
  92         return merge_blobs(the_repository->index, path,
  93                            base, our, their, size);
  94 }
  95
  96 static void *origin(struct merge_list *entry, unsigned long *size)
  97 {
  98         enum object_type type;
  99         while (entry) {
 100                 if (entry->stage == 2)
 101                         return repo_read_object_file(the_repository,
 102                                                      &entry->blob->object.oid,
 103                                                      &type, size);
 104                 entry = entry->link;
 105         }
 106         return NULL;
 107 }
 108
 109 static int show_outf(void *priv UNUSED, mmbuffer_t *mb, int nbuf)
 110 {
 111         int i;
 112         for (i = 0; i < nbuf; i++)
 113                 printf("%.*s", (int) mb[i].size, mb[i].ptr);
 114         return 0;
 115 }
 116
 117 static void show_diff(struct merge_list *entry)
 118 {
 119         unsigned long size;
 120         mmfile_t src, dst;
 121         xpparam_t xpp;
 122         xdemitconf_t xecfg;
 123         xdemitcb_t ecb = { .out_line = show_outf };
 124
 125         memset(&xpp, 0, sizeof(xpp));
 126         xpp.flags = 0;
 127         memset(&xecfg, 0, sizeof(xecfg));
 128         xecfg.ctxlen = 3;
 129
 130         src.ptr = origin(entry, &size);
 131         if (!src.ptr)
 132                 size = 0;
 133         src.size = size;
 134         dst.ptr = result(entry, &size);
 135         if (!dst.ptr)
 136                 size = 0;
 137         dst.size = size;
 138         if (xdi_diff(&src, &dst, &xpp, &xecfg, &ecb))
 139                 die("unable to generate diff");
 140         free(src.ptr);
 141         free(dst.ptr);
 142 }
 143
 144 static void show_result_list(struct merge_list *entry)
 145 {
 146         printf("%s\n", explanation(entry));
 147         do {
 148                 struct merge_list *link = entry->link;
 149                 static const char *desc[4] = { "result", "base", "our", "their" };
 150                 printf("  %-6s %o %s %s\n", desc[entry->stage], entry->mode, oid_to_hex(&entry->blob->object.oid), entry->path);
 151                 entry = link;
 152         } while (entry);
 153 }
 154
 155 static void show_result(void)
 156 {
 157         struct merge_list *walk;
 158
 159         walk = merge_result;
 160         while (walk) {
 161                 show_result_list(walk);
 162                 show_diff(walk);
 163                 walk = walk->next;
 164         }
 165 }
 166
 167 /* An empty entry never compares same, not even to another empty entry */
 168 static int same_entry(struct name_entry *a, struct name_entry *b)
 169 {
 170         return  !is_null_oid(&a->oid) &&
 171                 !is_null_oid(&b->oid) &&
 172                 oideq(&a->oid, &b->oid) &&
 173                 a->mode == b->mode;
 174 }
 175
 176 static int both_empty(struct name_entry *a, struct name_entry *b)
 177 {
 178         return is_null_oid(&a->oid) && is_null_oid(&b->oid);
 179 }
 180
 181 static struct merge_list *create_entry(unsigned stage, unsigned mode, const struct object_id *oid, const char *path)
 182 {
 183         struct merge_list *res = xcalloc(1, sizeof(*res));
 184
 185         res->stage = stage;
 186         res->path = path;
 187         res->mode = mode;
 188         res->blob = lookup_blob(the_repository, oid);
 189         return res;
 190 }
 191
 192 static char *traverse_path(const struct traverse_info *info, const struct name_entry *n)
 193 {
 194         struct strbuf buf = STRBUF_INIT;
 195         strbuf_make_traverse_path(&buf, info, n->path, n->pathlen);
 196         return strbuf_detach(&buf, NULL);
 197 }
 198
 199 static void resolve(const struct traverse_info *info, struct name_entry *ours, struct name_entry *result)
 200 {
 201         struct merge_list *orig, *final;
 202         const char *path;
 203
 204         /* If it's already ours, don't bother showing it */
 205         if (!ours)
 206                 return;
 207
 208         path = traverse_path(info, result);
 209         orig = create_entry(2, ours->mode, &ours->oid, path);
 210         final = create_entry(0, result->mode, &result->oid, path);
 211
 212         final->link = orig;
 213
 214         add_merge_entry(final);
 215 }
 216
 217 static void unresolved_directory(const struct traverse_info *info,
 218                                  struct name_entry n[3])
 219 {
 220         struct repository *r = the_repository;
 221         char *newbase;
 222         struct name_entry *p;
 223         struct tree_desc t[3];
 224         void *buf0, *buf1, *buf2;
 225
 226         for (p = n; p < n + 3; p++) {
 227                 if (p->mode && S_ISDIR(p->mode))
 228                         break;
 229         }
 230         if (n + 3 <= p)
 231                 return; /* there is no tree here */
 232
 233         newbase = traverse_path(info, p);
 234
 235 #define ENTRY_OID(e) (((e)->mode && S_ISDIR((e)->mode)) ? &(e)->oid : NULL)
 236         buf0 = fill_tree_descriptor(r, t + 0, ENTRY_OID(n + 0));
 237         buf1 = fill_tree_descriptor(r, t + 1, ENTRY_OID(n + 1));
 238         buf2 = fill_tree_descriptor(r, t + 2, ENTRY_OID(n + 2));
 239 #undef ENTRY_OID
 240
 241         trivial_merge_trees(t, newbase);
 242
 243         free(buf0);
 244         free(buf1);
 245         free(buf2);
 246         free(newbase);
 247 }
 248
 249
 250 static struct merge_list *link_entry(unsigned stage, const struct traverse_info *info, struct name_entry *n, struct merge_list *entry)
 251 {
 252         const char *path;
 253         struct merge_list *link;
 254
 255         if (!n->mode)
 256                 return entry;
 257         if (entry)
 258                 path = entry->path;
 259         else
 260                 path = traverse_path(info, n);
 261         link = create_entry(stage, n->mode, &n->oid, path);
 262         link->link = entry;
 263         return link;
 264 }
 265
 266 static void unresolved(const struct traverse_info *info, struct name_entry n[3])
 267 {
 268         struct merge_list *entry = NULL;
 269         int i;
 270         unsigned dirmask = 0, mask = 0;
 271
 272         for (i = 0; i < 3; i++) {
 273                 mask |= (1 << i);
 274                 /*
 275                  * Treat missing entries as directories so that we return
 276                  * after unresolved_directory has handled this.
 277                  */
 278                 if (!n[i].mode || S_ISDIR(n[i].mode))
 279                         dirmask |= (1 << i);
 280         }
 281
 282         unresolved_directory(info, n);
 283
 284         if (dirmask == mask)
 285                 return;
 286
 287         if (n[2].mode && !S_ISDIR(n[2].mode))
 288                 entry = link_entry(3, info, n + 2, entry);
 289         if (n[1].mode && !S_ISDIR(n[1].mode))
 290                 entry = link_entry(2, info, n + 1, entry);
 291         if (n[0].mode && !S_ISDIR(n[0].mode))
 292                 entry = link_entry(1, info, n + 0, entry);
 293
 294         add_merge_entry(entry);
 295 }
 296
 297 /*
 298  * Merge two trees together (t[1] and t[2]), using a common base (t[0])
 299  * as the origin.
 300  *
 301  * This walks the (sorted) trees in lock-step, checking every possible
 302  * name. Note that directories automatically sort differently from other
 303  * files (see "base_name_compare"), so you'll never see file/directory
 304  * conflicts, because they won't ever compare the same.
 305  *
 306  * IOW, if a directory changes to a filename, it will automatically be
 307  * seen as the directory going away, and the filename being created.
 308  *
 309  * Think of this as a three-way diff.
 310  *
 311  * The output will be either:
 312  *  - successful merge
 313  *       "0 mode sha1 filename"
 314  *    NOTE NOTE NOTE! FIXME! We really really need to walk the index
 315  *    in parallel with this too!
 316  *
 317  *  - conflict:
 318  *      "1 mode sha1 filename"
 319  *      "2 mode sha1 filename"
 320  *      "3 mode sha1 filename"
 321  *    where not all of the 1/2/3 lines may exist, of course.
 322  *
 323  * The successful merge rules are the same as for the three-way merge
 324  * in git-read-tree.
 325  */
 326 static int threeway_callback(int n UNUSED, unsigned long mask,
 327                              unsigned long dirmask UNUSED,
 328                              struct name_entry *entry, struct traverse_info *info)
 329 {
 330         /* Same in both? */
 331         if (same_entry(entry+1, entry+2) || both_empty(entry+1, entry+2)) {
 332                 /* Modified, added or removed identically */
 333                 resolve(info, NULL, entry+1);
 334                 return mask;
 335         }
 336
 337         if (same_entry(entry+0, entry+1)) {
 338                 if (!is_null_oid(&entry[2].oid) && !S_ISDIR(entry[2].mode)) {
 339                         /* We did not touch, they modified -- take theirs */
 340                         resolve(info, entry+1, entry+2);
 341                         return mask;
 342                 }
 343                 /*
 344                  * If we did not touch a directory but they made it
 345                  * into a file, we fall through and unresolved()
 346                  * recurses down.  Likewise for the opposite case.
 347                  */
 348         }
 349
 350         if (same_entry(entry+0, entry+2) || both_empty(entry+0, entry+2)) {
 351                 /* We added, modified or removed, they did not touch -- take ours */
 352                 resolve(info, NULL, entry+1);
 353                 return mask;
 354         }
 355
 356         unresolved(info, entry);
 357         return mask;
 358 }
 359
 360 static void trivial_merge_trees(struct tree_desc t[3], const char *base)
 361 {
 362         struct traverse_info info;
 363
 364         setup_traverse_info(&info, base);
 365         info.fn = threeway_callback;
 366         traverse_trees(the_repository->index, 3, t, &info);
 367 }
 368
 369 static void *get_tree_descriptor(struct repository *r,
 370                                  struct tree_desc *desc,
 371                                  const char *rev)
 372 {
 373         struct object_id oid;
 374         void *buf;
 375
 376         if (repo_get_oid(r, rev, &oid))
 377                 die("unknown rev %s", rev);
 378         buf = fill_tree_descriptor(r, desc, &oid);
 379         if (!buf)
 380                 die("%s is not a tree", rev);
 381         return buf;
 382 }
 383
 384 static int trivial_merge(const char *base,
 385                          const char *branch1,
 386                          const char *branch2)
 387 {
 388         struct repository *r = the_repository;
 389         struct tree_desc t[3];
 390         void *buf1, *buf2, *buf3;
 391
 392         buf1 = get_tree_descriptor(r, t+0, base);
 393         buf2 = get_tree_descriptor(r, t+1, branch1);
 394         buf3 = get_tree_descriptor(r, t+2, branch2);
 395         trivial_merge_trees(t, "");
 396         free(buf1);
 397         free(buf2);
 398         free(buf3);
 399
 400         show_result();
 401         return 0;
 402 }
 403
 404 enum mode {
 405         MODE_UNKNOWN,
 406         MODE_TRIVIAL,
 407         MODE_REAL,
 408 };
 409
 410 struct merge_tree_options {
 411         int mode;
 412         int allow_unrelated_histories;
 413         int show_messages;
 414         int name_only;
 415         int use_stdin;
 416         struct merge_options merge_options;
 417 };
 418
 419 static int real_merge(struct merge_tree_options *o,
 420                       const char *merge_base,
 421                       const char *branch1, const char *branch2,
 422                       const char *prefix)
 423 {
 424         struct commit *parent1, *parent2;
 425         struct commit_list *merge_bases = NULL;
 426         struct merge_result result = { 0 };
 427         int show_messages = o->show_messages;
 428         struct merge_options opt;
 429
 430         copy_merge_options(&opt, &o->merge_options);
 431         opt.show_rename_progress = 0;
 432
 433         opt.branch1 = branch1;
 434         opt.branch2 = branch2;
 435
 436         if (merge_base) {
 437                 struct tree *base_tree, *parent1_tree, *parent2_tree;
 438
 439                 /*
 440                  * We actually only need the trees because we already
 441                  * have a merge base.
 442                  */
 443                 struct object_id base_oid, head_oid, merge_oid;
 444
 445                 if (repo_get_oid_treeish(the_repository, merge_base, &base_oid))
 446                         die(_("could not parse as tree '%s'"), merge_base);
 447                 base_tree = parse_tree_indirect(&base_oid);
 448                 if (!base_tree)
 449                         die(_("unable to read tree (%s)"), oid_to_hex(&base_oid));
 450                 if (repo_get_oid_treeish(the_repository, branch1, &head_oid))
 451                         die(_("could not parse as tree '%s'"), branch1);
 452                 parent1_tree = parse_tree_indirect(&head_oid);
 453                 if (!parent1_tree)
 454                         die(_("unable to read tree (%s)"), oid_to_hex(&head_oid));
 455                 if (repo_get_oid_treeish(the_repository, branch2, &merge_oid))
 456                         die(_("could not parse as tree '%s'"), branch2);
 457                 parent2_tree = parse_tree_indirect(&merge_oid);
 458                 if (!parent2_tree)
 459                         die(_("unable to read tree (%s)"), oid_to_hex(&merge_oid));
 460
 461                 opt.ancestor = merge_base;
 462                 merge_incore_nonrecursive(&opt, base_tree, parent1_tree, parent2_tree, &result);
 463         } else {
 464                 parent1 = get_merge_parent(branch1);
 465                 if (!parent1)
 466                         help_unknown_ref(branch1, "merge-tree",
 467                                          _("not something we can merge"));
 468
 469                 parent2 = get_merge_parent(branch2);
 470                 if (!parent2)
 471                         help_unknown_ref(branch2, "merge-tree",
 472                                          _("not something we can merge"));
 473
 474                 /*
 475                  * Get the merge bases, in reverse order; see comment above
 476                  * merge_incore_recursive in merge-ort.h
 477                  */
 478                 if (repo_get_merge_bases(the_repository, parent1,
 479                                          parent2, &merge_bases) < 0)
 480                         exit(128);
 481                 if (!merge_bases && !o->allow_unrelated_histories)
 482                         die(_("refusing to merge unrelated histories"));
 483                 merge_bases = reverse_commit_list(merge_bases);
 484                 merge_incore_recursive(&opt, merge_bases, parent1, parent2, &result);
 485         }
 486
 487         if (result.clean < 0)
 488                 die(_("failure to merge"));
 489
 490         if (show_messages == -1)
 491                 show_messages = !result.clean;
 492
 493         if (o->use_stdin)
 494                 printf("%d%c", result.clean, line_termination);
 495         printf("%s%c", oid_to_hex(&result.tree->object.oid), line_termination);
 496         if (!result.clean) {
 497                 struct string_list conflicted_files = STRING_LIST_INIT_NODUP;
 498                 const char *last = NULL;
 499                 int i;
 500
 501                 merge_get_conflicted_files(&result, &conflicted_files);
 502                 for (i = 0; i < conflicted_files.nr; i++) {
 503                         const char *name = conflicted_files.items[i].string;
 504                         struct stage_info *c = conflicted_files.items[i].util;
 505                         if (!o->name_only)
 506                                 printf("%06o %s %d\t",
 507                                        c->mode, oid_to_hex(&c->oid), c->stage);
 508                         else if (last && !strcmp(last, name))
 509                                 continue;
 510                         write_name_quoted_relative(
 511                                 name, prefix, stdout, line_termination);
 512                         last = name;
 513                 }
 514                 string_list_clear(&conflicted_files, 1);
 515         }
 516         if (show_messages) {
 517                 putchar(line_termination);
 518                 merge_display_update_messages(&opt, line_termination == '\0',
 519                                               &result);
 520         }
 521         if (o->use_stdin)
 522                 putchar(line_termination);
 523         merge_finalize(&opt, &result);
 524         clear_merge_options(&opt);
 525         return !result.clean; /* result.clean < 0 handled above */
 526 }
 527
 528 int cmd_merge_tree(int argc, const char **argv, const char *prefix)
 529 {
 530         struct merge_tree_options o = { .show_messages = -1 };
 531         struct strvec xopts = STRVEC_INIT;
 532         int expected_remaining_argc;
 533         int original_argc;
 534         const char *merge_base = NULL;
 535
 536         const char * const merge_tree_usage[] = {
 537                 N_("git merge-tree [--write-tree] [<options>] <branch1> <branch2>"),
 538                 N_("git merge-tree [--trivial-merge] <base-tree> <branch1> <branch2>"),
 539                 NULL
 540         };
 541         struct option mt_options[] = {
 542                 OPT_CMDMODE(0, "write-tree", &o.mode,
 543                             N_("do a real merge instead of a trivial merge"),
 544                             MODE_REAL),
 545                 OPT_CMDMODE(0, "trivial-merge", &o.mode,
 546                             N_("do a trivial merge only"), MODE_TRIVIAL),
 547                 OPT_BOOL(0, "messages", &o.show_messages,
 548                          N_("also show informational/conflict messages")),
 549                 OPT_SET_INT('z', NULL, &line_termination,
 550                             N_("separate paths with the NUL character"), '\0'),
 551                 OPT_BOOL_F(0, "name-only",
 552                            &o.name_only,
 553                            N_("list filenames without modes/oids/stages"),
 554                            PARSE_OPT_NONEG),
 555                 OPT_BOOL_F(0, "allow-unrelated-histories",
 556                            &o.allow_unrelated_histories,
 557                            N_("allow merging unrelated histories"),
 558                            PARSE_OPT_NONEG),
 559                 OPT_BOOL_F(0, "stdin",
 560                            &o.use_stdin,
 561                            N_("perform multiple merges, one per line of input"),
 562                            PARSE_OPT_NONEG),
 563                 OPT_STRING(0, "merge-base",
 564                            &merge_base,
 565                            N_("tree-ish"),
 566                            N_("specify a merge-base for the merge")),
 567                 OPT_STRVEC('X', "strategy-option", &xopts, N_("option=value"),
 568                         N_("option for selected merge strategy")),
 569                 OPT_END()
 570         };
 571
 572         /* Init merge options */
 573         init_merge_options(&o.merge_options, the_repository);
 574
 575         /* Parse arguments */
 576         original_argc = argc - 1; /* ignoring argv[0] */
 577         argc = parse_options(argc, argv, prefix, mt_options,
 578                              merge_tree_usage, PARSE_OPT_STOP_AT_NON_OPTION);
 579
 580         if (xopts.nr && o.mode == MODE_TRIVIAL)
 581                 die(_("--trivial-merge is incompatible with all other options"));
 582         for (int x = 0; x < xopts.nr; x++)
 583                 if (parse_merge_opt(&o.merge_options, xopts.v[x]))
 584                         die(_("unknown strategy option: -X%s"), xopts.v[x]);
 585
 586         /* Handle --stdin */
 587         if (o.use_stdin) {
 588                 struct strbuf buf = STRBUF_INIT;
 589
 590                 if (o.mode == MODE_TRIVIAL)
 591                         die(_("--trivial-merge is incompatible with all other options"));
 592                 if (merge_base)
 593                         die(_("options '%s' and '%s' cannot be used together"),
 594                             "--merge-base", "--stdin");
 595                 line_termination = '\0';
 596                 while (strbuf_getline_lf(&buf, stdin) != EOF) {
 597                         struct strbuf **split;
 598                         int result;
 599                         const char *input_merge_base = NULL;
 600
 601                         split = strbuf_split(&buf, ' ');
 602                         if (!split[0] || !split[1])
 603                                 die(_("malformed input line: '%s'."), buf.buf);
 604                         strbuf_rtrim(split[0]);
 605                         strbuf_rtrim(split[1]);
 606
 607                         /* parse the merge-base */
 608                         if (!strcmp(split[1]->buf, "--")) {
 609                                 input_merge_base = split[0]->buf;
 610                         }
 611
 612                         if (input_merge_base && split[2] && split[3] && !split[4]) {
 613                                 strbuf_rtrim(split[2]);
 614                                 strbuf_rtrim(split[3]);
 615                                 result = real_merge(&o, input_merge_base, split[2]->buf, split[3]->buf, prefix);
 616                         } else if (!input_merge_base && !split[2]) {
 617                                 result = real_merge(&o, NULL, split[0]->buf, split[1]->buf, prefix);
 618                         } else {
 619                                 die(_("malformed input line: '%s'."), buf.buf);
 620                         }
 621
 622                         if (result < 0)
 623                                 die(_("merging cannot continue; got unclean result of %d"), result);
 624                         strbuf_list_free(split);
 625                 }
 626                 strbuf_release(&buf);
 627                 return 0;
 628         }
 629
 630         /* Figure out which mode to use */
 631         switch (o.mode) {
 632         default:
 633                 BUG("unexpected command mode %d", o.mode);
 634         case MODE_UNKNOWN:
 635                 switch (argc) {
 636                 default:
 637                         usage_with_options(merge_tree_usage, mt_options);
 638                 case 2:
 639                         o.mode = MODE_REAL;
 640                         break;
 641                 case 3:
 642                         o.mode = MODE_TRIVIAL;
 643                         break;
 644                 }
 645                 expected_remaining_argc = argc;
 646                 break;
 647         case MODE_REAL:
 648                 expected_remaining_argc = 2;
 649                 break;
 650         case MODE_TRIVIAL:
 651                 expected_remaining_argc = 3;
 652                 /* Removal of `--trivial-merge` is expected */
 653                 original_argc--;
 654                 break;
 655         }
 656         if (o.mode == MODE_TRIVIAL && argc < original_argc)
 657                 die(_("--trivial-merge is incompatible with all other options"));
 658
 659         if (argc != expected_remaining_argc)
 660                 usage_with_options(merge_tree_usage, mt_options);
 661
 662         git_config(git_default_config, NULL);
 663
 664         /* Do the relevant type of merge */
 665         if (o.mode == MODE_REAL)
 666                 return real_merge(&o, merge_base, argv[0], argv[1], prefix);
 667         else
 668                 return trivial_merge(argv[0], argv[1], argv[2]);
 669 }