builtin-merge.c

   1 /*
   2  * Builtin "git merge"
   3  *
   4  * Copyright (c) 2008 Miklos Vajna <vmiklos@frugalware.org>
   5  *
   6  * Based on git-merge.sh by Junio C Hamano.
   7  */
   8
   9 #include "cache.h"
  10 #include "parse-options.h"
  11 #include "builtin.h"
  12 #include "run-command.h"
  13 #include "diff.h"
  14 #include "refs.h"
  15 #include "commit.h"
  16 #include "diffcore.h"
  17 #include "revision.h"
  18 #include "unpack-trees.h"
  19 #include "cache-tree.h"
  20 #include "dir.h"
  21 #include "utf8.h"
  22 #include "log-tree.h"
  23 #include "color.h"
  24 #include "rerere.h"
  25
  26 #define DEFAULT_TWOHEAD (1<<0)
  27 #define DEFAULT_OCTOPUS (1<<1)
  28 #define NO_FAST_FORWARD (1<<2)
  29 #define NO_TRIVIAL      (1<<3)
  30
  31 struct strategy {
  32         const char *name;
  33         unsigned attr;
  34 };
  35
  36 static const char * const builtin_merge_usage[] = {
  37         "git-merge [options] <remote>...",
  38         "git-merge [options] <msg> HEAD <remote>",
  39         NULL
  40 };
  41
  42 static int show_diffstat = 1, option_log, squash;
  43 static int option_commit = 1, allow_fast_forward = 1;
  44 static int allow_trivial = 1, have_message;
  45 static struct strbuf merge_msg;
  46 static struct commit_list *remoteheads;
  47 static unsigned char head[20], stash[20];
  48 static struct strategy **use_strategies;
  49 static size_t use_strategies_nr, use_strategies_alloc;
  50 static const char *branch;
  51
  52 static struct strategy all_strategy[] = {
  53         { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
  54         { "octopus",    DEFAULT_OCTOPUS },
  55         { "resolve",    0 },
  56         { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
  57         { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
  58 };
  59
  60 static const char *pull_twohead, *pull_octopus;
  61
  62 static int option_parse_message(const struct option *opt,
  63                                 const char *arg, int unset)
  64 {
  65         struct strbuf *buf = opt->value;
  66
  67         if (unset)
  68                 strbuf_setlen(buf, 0);
  69         else if (arg) {
  70                 strbuf_addf(buf, "%s\n\n", arg);
  71                 have_message = 1;
  72         } else
  73                 return error("switch `m' requires a value");
  74         return 0;
  75 }
  76
  77 static struct strategy *get_strategy(const char *name)
  78 {
  79         int i;
  80         struct strbuf err;
  81
  82         if (!name)
  83                 return NULL;
  84
  85         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
  86                 if (!strcmp(name, all_strategy[i].name))
  87                         return &all_strategy[i];
  88
  89         strbuf_init(&err, 0);
  90         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
  91                 strbuf_addf(&err, " %s", all_strategy[i].name);
  92         fprintf(stderr, "Could not find merge strategy '%s'.\n", name);
  93         fprintf(stderr, "Available strategies are:%s.\n", err.buf);
  94         exit(1);
  95 }
  96
  97 static void append_strategy(struct strategy *s)
  98 {
  99         ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
 100         use_strategies[use_strategies_nr++] = s;
 101 }
 102
 103 static int option_parse_strategy(const struct option *opt,
 104                                  const char *name, int unset)
 105 {
 106         if (unset)
 107                 return 0;
 108
 109         append_strategy(get_strategy(name));
 110         return 0;
 111 }
 112
 113 static int option_parse_n(const struct option *opt,
 114                           const char *arg, int unset)
 115 {
 116         show_diffstat = unset;
 117         return 0;
 118 }
 119
 120 static struct option builtin_merge_options[] = {
 121         { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
 122                 "do not show a diffstat at the end of the merge",
 123                 PARSE_OPT_NOARG, option_parse_n },
 124         OPT_BOOLEAN(0, "stat", &show_diffstat,
 125                 "show a diffstat at the end of the merge"),
 126         OPT_BOOLEAN(0, "summary", &show_diffstat, "(synonym to --stat)"),
 127         OPT_BOOLEAN(0, "log", &option_log,
 128                 "add list of one-line log to merge commit message"),
 129         OPT_BOOLEAN(0, "squash", &squash,
 130                 "create a single commit instead of doing a merge"),
 131         OPT_BOOLEAN(0, "commit", &option_commit,
 132                 "perform a commit if the merge succeeds (default)"),
 133         OPT_BOOLEAN(0, "ff", &allow_fast_forward,
 134                 "allow fast forward (default)"),
 135         OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
 136                 "merge strategy to use", option_parse_strategy),
 137         OPT_CALLBACK('m', "message", &merge_msg, "message",
 138                 "message to be used for the merge commit (if any)",
 139                 option_parse_message),
 140         OPT_END()
 141 };
 142
 143 /* Cleans up metadata that is uninteresting after a succeeded merge. */
 144 static void drop_save(void)
 145 {
 146         unlink(git_path("MERGE_HEAD"));
 147         unlink(git_path("MERGE_MSG"));
 148 }
 149
 150 static void save_state(void)
 151 {
 152         int len;
 153         struct child_process cp;
 154         struct strbuf buffer = STRBUF_INIT;
 155         const char *argv[] = {"stash", "create", NULL};
 156
 157         memset(&cp, 0, sizeof(cp));
 158         cp.argv = argv;
 159         cp.out = -1;
 160         cp.git_cmd = 1;
 161
 162         if (start_command(&cp))
 163                 die("could not run stash.");
 164         len = strbuf_read(&buffer, cp.out, 1024);
 165         close(cp.out);
 166
 167         if (finish_command(&cp) || len < 0)
 168                 die("stash failed");
 169         else if (!len)
 170                 return;
 171         strbuf_setlen(&buffer, buffer.len-1);
 172         if (get_sha1(buffer.buf, stash))
 173                 die("not a valid object: %s", buffer.buf);
 174 }
 175
 176 static void reset_hard(unsigned const char *sha1, int verbose)
 177 {
 178         int i = 0;
 179         const char *args[6];
 180
 181         args[i++] = "read-tree";
 182         if (verbose)
 183                 args[i++] = "-v";
 184         args[i++] = "--reset";
 185         args[i++] = "-u";
 186         args[i++] = sha1_to_hex(sha1);
 187         args[i] = NULL;
 188
 189         if (run_command_v_opt(args, RUN_GIT_CMD))
 190                 die("read-tree failed");
 191 }
 192
 193 static void restore_state(void)
 194 {
 195         struct strbuf sb;
 196         const char *args[] = { "stash", "apply", NULL, NULL };
 197
 198         if (is_null_sha1(stash))
 199                 return;
 200
 201         reset_hard(head, 1);
 202
 203         strbuf_init(&sb, 0);
 204         args[2] = sha1_to_hex(stash);
 205
 206         /*
 207          * It is OK to ignore error here, for example when there was
 208          * nothing to restore.
 209          */
 210         run_command_v_opt(args, RUN_GIT_CMD);
 211
 212         strbuf_release(&sb);
 213         refresh_cache(REFRESH_QUIET);
 214 }
 215
 216 /* This is called when no merge was necessary. */
 217 static void finish_up_to_date(const char *msg)
 218 {
 219         printf("%s%s\n", squash ? " (nothing to squash)" : "", msg);
 220         drop_save();
 221 }
 222
 223 static void squash_message(void)
 224 {
 225         struct rev_info rev;
 226         struct commit *commit;
 227         struct strbuf out;
 228         struct commit_list *j;
 229         int fd;
 230
 231         printf("Squash commit -- not updating HEAD\n");
 232         fd = open(git_path("SQUASH_MSG"), O_WRONLY | O_CREAT, 0666);
 233         if (fd < 0)
 234                 die("Could not write to %s", git_path("SQUASH_MSG"));
 235
 236         init_revisions(&rev, NULL);
 237         rev.ignore_merges = 1;
 238         rev.commit_format = CMIT_FMT_MEDIUM;
 239
 240         commit = lookup_commit(head);
 241         commit->object.flags |= UNINTERESTING;
 242         add_pending_object(&rev, &commit->object, NULL);
 243
 244         for (j = remoteheads; j; j = j->next)
 245                 add_pending_object(&rev, &j->item->object, NULL);
 246
 247         setup_revisions(0, NULL, &rev, NULL);
 248         if (prepare_revision_walk(&rev))
 249                 die("revision walk setup failed");
 250
 251         strbuf_init(&out, 0);
 252         strbuf_addstr(&out, "Squashed commit of the following:\n");
 253         while ((commit = get_revision(&rev)) != NULL) {
 254                 strbuf_addch(&out, '\n');
 255                 strbuf_addf(&out, "commit %s\n",
 256                         sha1_to_hex(commit->object.sha1));
 257                 pretty_print_commit(rev.commit_format, commit, &out, rev.abbrev,
 258                         NULL, NULL, rev.date_mode, 0);
 259         }
 260         write(fd, out.buf, out.len);
 261         close(fd);
 262         strbuf_release(&out);
 263 }
 264
 265 static int run_hook(const char *name)
 266 {
 267         struct child_process hook;
 268         const char *argv[3], *env[2];
 269         char index[PATH_MAX];
 270
 271         argv[0] = git_path("hooks/%s", name);
 272         if (access(argv[0], X_OK) < 0)
 273                 return 0;
 274
 275         snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", get_index_file());
 276         env[0] = index;
 277         env[1] = NULL;
 278
 279         if (squash)
 280                 argv[1] = "1";
 281         else
 282                 argv[1] = "0";
 283         argv[2] = NULL;
 284
 285         memset(&hook, 0, sizeof(hook));
 286         hook.argv = argv;
 287         hook.no_stdin = 1;
 288         hook.stdout_to_stderr = 1;
 289         hook.env = env;
 290
 291         return run_command(&hook);
 292 }
 293
 294 static void finish(const unsigned char *new_head, const char *msg)
 295 {
 296         struct strbuf reflog_message;
 297
 298         strbuf_init(&reflog_message, 0);
 299         if (!msg)
 300                 strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
 301         else {
 302                 printf("%s\n", msg);
 303                 strbuf_addf(&reflog_message, "%s: %s",
 304                         getenv("GIT_REFLOG_ACTION"), msg);
 305         }
 306         if (squash) {
 307                 squash_message();
 308         } else {
 309                 if (!merge_msg.len)
 310                         printf("No merge message -- not updating HEAD\n");
 311                 else {
 312                         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 313                         update_ref(reflog_message.buf, "HEAD",
 314                                 new_head, head, 0,
 315                                 DIE_ON_ERR);
 316                         /*
 317                          * We ignore errors in 'gc --auto', since the
 318                          * user should see them.
 319                          */
 320                         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 321                 }
 322         }
 323         if (new_head && show_diffstat) {
 324                 struct diff_options opts;
 325                 diff_setup(&opts);
 326                 opts.output_format |=
 327                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 328                 opts.detect_rename = DIFF_DETECT_RENAME;
 329                 if (diff_use_color_default > 0)
 330                         DIFF_OPT_SET(&opts, COLOR_DIFF);
 331                 if (diff_setup_done(&opts) < 0)
 332                         die("diff_setup_done failed");
 333                 diff_tree_sha1(head, new_head, "", &opts);
 334                 diffcore_std(&opts);
 335                 diff_flush(&opts);
 336         }
 337
 338         /* Run a post-merge hook */
 339         run_hook("post-merge");
 340
 341         strbuf_release(&reflog_message);
 342 }
 343
 344 /* Get the name for the merge commit's message. */
 345 static void merge_name(const char *remote, struct strbuf *msg)
 346 {
 347         struct object *remote_head;
 348         unsigned char branch_head[20], buf_sha[20];
 349         struct strbuf buf;
 350         const char *ptr;
 351         int len, early;
 352
 353         memset(branch_head, 0, sizeof(branch_head));
 354         remote_head = peel_to_type(remote, 0, NULL, OBJ_COMMIT);
 355         if (!remote_head)
 356                 die("'%s' does not point to a commit", remote);
 357
 358         strbuf_init(&buf, 0);
 359         strbuf_addstr(&buf, "refs/heads/");
 360         strbuf_addstr(&buf, remote);
 361         resolve_ref(buf.buf, branch_head, 0, 0);
 362
 363         if (!hashcmp(remote_head->sha1, branch_head)) {
 364                 strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
 365                         sha1_to_hex(branch_head), remote);
 366                 return;
 367         }
 368
 369         /* See if remote matches <name>^^^.. or <name>~<number> */
 370         for (len = 0, ptr = remote + strlen(remote);
 371              remote < ptr && ptr[-1] == '^';
 372              ptr--)
 373                 len++;
 374         if (len)
 375                 early = 1;
 376         else {
 377                 early = 0;
 378                 ptr = strrchr(remote, '~');
 379                 if (ptr) {
 380                         int seen_nonzero = 0;
 381
 382                         len++; /* count ~ */
 383                         while (*++ptr && isdigit(*ptr)) {
 384                                 seen_nonzero |= (*ptr != '0');
 385                                 len++;
 386                         }
 387                         if (*ptr)
 388                                 len = 0; /* not ...~<number> */
 389                         else if (seen_nonzero)
 390                                 early = 1;
 391                         else if (len == 1)
 392                                 early = 1; /* "name~" is "name~1"! */
 393                 }
 394         }
 395         if (len) {
 396                 struct strbuf truname = STRBUF_INIT;
 397                 strbuf_addstr(&truname, "refs/heads/");
 398                 strbuf_addstr(&truname, remote);
 399                 strbuf_setlen(&truname, truname.len - len);
 400                 if (resolve_ref(truname.buf, buf_sha, 0, 0)) {
 401                         strbuf_addf(msg,
 402                                     "%s\t\tbranch '%s'%s of .\n",
 403                                     sha1_to_hex(remote_head->sha1),
 404                                     truname.buf + 11,
 405                                     (early ? " (early part)" : ""));
 406                         return;
 407                 }
 408         }
 409
 410         if (!strcmp(remote, "FETCH_HEAD") &&
 411                         !access(git_path("FETCH_HEAD"), R_OK)) {
 412                 FILE *fp;
 413                 struct strbuf line;
 414                 char *ptr;
 415
 416                 strbuf_init(&line, 0);
 417                 fp = fopen(git_path("FETCH_HEAD"), "r");
 418                 if (!fp)
 419                         die("could not open %s for reading: %s",
 420                                 git_path("FETCH_HEAD"), strerror(errno));
 421                 strbuf_getline(&line, fp, '\n');
 422                 fclose(fp);
 423                 ptr = strstr(line.buf, "\tnot-for-merge\t");
 424                 if (ptr)
 425                         strbuf_remove(&line, ptr-line.buf+1, 13);
 426                 strbuf_addbuf(msg, &line);
 427                 strbuf_release(&line);
 428                 return;
 429         }
 430         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
 431                 sha1_to_hex(remote_head->sha1), remote);
 432 }
 433
 434 static int git_merge_config(const char *k, const char *v, void *cb)
 435 {
 436         if (branch && !prefixcmp(k, "branch.") &&
 437                 !prefixcmp(k + 7, branch) &&
 438                 !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
 439                 const char **argv;
 440                 int argc;
 441                 char *buf;
 442
 443                 buf = xstrdup(v);
 444                 argc = split_cmdline(buf, &argv);
 445                 if (argc < 0)
 446                         die("Bad branch.%s.mergeoptions string", branch);
 447                 argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
 448                 memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
 449                 argc++;
 450                 parse_options(argc, argv, builtin_merge_options,
 451                               builtin_merge_usage, 0);
 452                 free(buf);
 453         }
 454
 455         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
 456                 show_diffstat = git_config_bool(k, v);
 457         else if (!strcmp(k, "pull.twohead"))
 458                 return git_config_string(&pull_twohead, k, v);
 459         else if (!strcmp(k, "pull.octopus"))
 460                 return git_config_string(&pull_octopus, k, v);
 461         else if (!strcmp(k, "merge.log") || !strcmp(k, "merge.summary"))
 462                 option_log = git_config_bool(k, v);
 463         return git_diff_ui_config(k, v, cb);
 464 }
 465
 466 static int read_tree_trivial(unsigned char *common, unsigned char *head,
 467                              unsigned char *one)
 468 {
 469         int i, nr_trees = 0;
 470         struct tree *trees[MAX_UNPACK_TREES];
 471         struct tree_desc t[MAX_UNPACK_TREES];
 472         struct unpack_trees_options opts;
 473
 474         memset(&opts, 0, sizeof(opts));
 475         opts.head_idx = 2;
 476         opts.src_index = &the_index;
 477         opts.dst_index = &the_index;
 478         opts.update = 1;
 479         opts.verbose_update = 1;
 480         opts.trivial_merges_only = 1;
 481         opts.merge = 1;
 482         trees[nr_trees] = parse_tree_indirect(common);
 483         if (!trees[nr_trees++])
 484                 return -1;
 485         trees[nr_trees] = parse_tree_indirect(head);
 486         if (!trees[nr_trees++])
 487                 return -1;
 488         trees[nr_trees] = parse_tree_indirect(one);
 489         if (!trees[nr_trees++])
 490                 return -1;
 491         opts.fn = threeway_merge;
 492         cache_tree_free(&active_cache_tree);
 493         for (i = 0; i < nr_trees; i++) {
 494                 parse_tree(trees[i]);
 495                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 496         }
 497         if (unpack_trees(nr_trees, t, &opts))
 498                 return -1;
 499         return 0;
 500 }
 501
 502 static void write_tree_trivial(unsigned char *sha1)
 503 {
 504         if (write_cache_as_tree(sha1, 0, NULL))
 505                 die("git write-tree failed to write a tree");
 506 }
 507
 508 static int try_merge_strategy(const char *strategy, struct commit_list *common,
 509                               const char *head_arg)
 510 {
 511         const char **args;
 512         int i = 0, ret;
 513         struct commit_list *j;
 514         struct strbuf buf;
 515
 516         args = xmalloc((4 + commit_list_count(common) +
 517                         commit_list_count(remoteheads)) * sizeof(char *));
 518         strbuf_init(&buf, 0);
 519         strbuf_addf(&buf, "merge-%s", strategy);
 520         args[i++] = buf.buf;
 521         for (j = common; j; j = j->next)
 522                 args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
 523         args[i++] = "--";
 524         args[i++] = head_arg;
 525         for (j = remoteheads; j; j = j->next)
 526                 args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
 527         args[i] = NULL;
 528         ret = run_command_v_opt(args, RUN_GIT_CMD);
 529         strbuf_release(&buf);
 530         i = 1;
 531         for (j = common; j; j = j->next)
 532                 free((void *)args[i++]);
 533         i += 2;
 534         for (j = remoteheads; j; j = j->next)
 535                 free((void *)args[i++]);
 536         free(args);
 537         return -ret;
 538 }
 539
 540 static void count_diff_files(struct diff_queue_struct *q,
 541                              struct diff_options *opt, void *data)
 542 {
 543         int *count = data;
 544
 545         (*count) += q->nr;
 546 }
 547
 548 static int count_unmerged_entries(void)
 549 {
 550         const struct index_state *state = &the_index;
 551         int i, ret = 0;
 552
 553         for (i = 0; i < state->cache_nr; i++)
 554                 if (ce_stage(state->cache[i]))
 555                         ret++;
 556
 557         return ret;
 558 }
 559
 560 static int checkout_fast_forward(unsigned char *head, unsigned char *remote)
 561 {
 562         struct tree *trees[MAX_UNPACK_TREES];
 563         struct unpack_trees_options opts;
 564         struct tree_desc t[MAX_UNPACK_TREES];
 565         int i, fd, nr_trees = 0;
 566         struct dir_struct dir;
 567         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 568
 569         refresh_cache(REFRESH_QUIET);
 570
 571         fd = hold_locked_index(lock_file, 1);
 572
 573         memset(&trees, 0, sizeof(trees));
 574         memset(&opts, 0, sizeof(opts));
 575         memset(&t, 0, sizeof(t));
 576         memset(&dir, 0, sizeof(dir));
 577         dir.show_ignored = 1;
 578         dir.exclude_per_dir = ".gitignore";
 579         opts.dir = &dir;
 580
 581         opts.head_idx = 1;
 582         opts.src_index = &the_index;
 583         opts.dst_index = &the_index;
 584         opts.update = 1;
 585         opts.verbose_update = 1;
 586         opts.merge = 1;
 587         opts.fn = twoway_merge;
 588
 589         trees[nr_trees] = parse_tree_indirect(head);
 590         if (!trees[nr_trees++])
 591                 return -1;
 592         trees[nr_trees] = parse_tree_indirect(remote);
 593         if (!trees[nr_trees++])
 594                 return -1;
 595         for (i = 0; i < nr_trees; i++) {
 596                 parse_tree(trees[i]);
 597                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 598         }
 599         if (unpack_trees(nr_trees, t, &opts))
 600                 return -1;
 601         if (write_cache(fd, active_cache, active_nr) ||
 602                 commit_locked_index(lock_file))
 603                 die("unable to write new index file");
 604         return 0;
 605 }
 606
 607 static void split_merge_strategies(const char *string, struct strategy **list,
 608                                    int *nr, int *alloc)
 609 {
 610         char *p, *q, *buf;
 611
 612         if (!string)
 613                 return;
 614
 615         buf = xstrdup(string);
 616         q = buf;
 617         for (;;) {
 618                 p = strchr(q, ' ');
 619                 if (!p) {
 620                         ALLOC_GROW(*list, *nr + 1, *alloc);
 621                         (*list)[(*nr)++].name = xstrdup(q);
 622                         free(buf);
 623                         return;
 624                 } else {
 625                         *p = '\0';
 626                         ALLOC_GROW(*list, *nr + 1, *alloc);
 627                         (*list)[(*nr)++].name = xstrdup(q);
 628                         q = ++p;
 629                 }
 630         }
 631 }
 632
 633 static void add_strategies(const char *string, unsigned attr)
 634 {
 635         struct strategy *list = NULL;
 636         int list_alloc = 0, list_nr = 0, i;
 637
 638         memset(&list, 0, sizeof(list));
 639         split_merge_strategies(string, &list, &list_nr, &list_alloc);
 640         if (list) {
 641                 for (i = 0; i < list_nr; i++)
 642                         append_strategy(get_strategy(list[i].name));
 643                 return;
 644         }
 645         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 646                 if (all_strategy[i].attr & attr)
 647                         append_strategy(&all_strategy[i]);
 648
 649 }
 650
 651 static int merge_trivial(void)
 652 {
 653         unsigned char result_tree[20], result_commit[20];
 654         struct commit_list *parent = xmalloc(sizeof(*parent));
 655
 656         write_tree_trivial(result_tree);
 657         printf("Wonderful.\n");
 658         parent->item = lookup_commit(head);
 659         parent->next = xmalloc(sizeof(*parent->next));
 660         parent->next->item = remoteheads->item;
 661         parent->next->next = NULL;
 662         commit_tree(merge_msg.buf, result_tree, parent, result_commit);
 663         finish(result_commit, "In-index merge");
 664         drop_save();
 665         return 0;
 666 }
 667
 668 static int finish_automerge(struct commit_list *common,
 669                             unsigned char *result_tree,
 670                             const char *wt_strategy)
 671 {
 672         struct commit_list *parents = NULL, *j;
 673         struct strbuf buf = STRBUF_INIT;
 674         unsigned char result_commit[20];
 675
 676         free_commit_list(common);
 677         if (allow_fast_forward) {
 678                 parents = remoteheads;
 679                 commit_list_insert(lookup_commit(head), &parents);
 680                 parents = reduce_heads(parents);
 681         } else {
 682                 struct commit_list **pptr = &parents;
 683
 684                 pptr = &commit_list_insert(lookup_commit(head),
 685                                 pptr)->next;
 686                 for (j = remoteheads; j; j = j->next)
 687                         pptr = &commit_list_insert(j->item, pptr)->next;
 688         }
 689         free_commit_list(remoteheads);
 690         strbuf_addch(&merge_msg, '\n');
 691         commit_tree(merge_msg.buf, result_tree, parents, result_commit);
 692         strbuf_addf(&buf, "Merge made by %s.", wt_strategy);
 693         finish(result_commit, buf.buf);
 694         strbuf_release(&buf);
 695         drop_save();
 696         return 0;
 697 }
 698
 699 static int suggest_conflicts(void)
 700 {
 701         FILE *fp;
 702         int pos;
 703
 704         fp = fopen(git_path("MERGE_MSG"), "a");
 705         if (!fp)
 706                 die("Could open %s for writing", git_path("MERGE_MSG"));
 707         fprintf(fp, "\nConflicts:\n");
 708         for (pos = 0; pos < active_nr; pos++) {
 709                 struct cache_entry *ce = active_cache[pos];
 710
 711                 if (ce_stage(ce)) {
 712                         fprintf(fp, "\t%s\n", ce->name);
 713                         while (pos + 1 < active_nr &&
 714                                         !strcmp(ce->name,
 715                                                 active_cache[pos + 1]->name))
 716                                 pos++;
 717                 }
 718         }
 719         fclose(fp);
 720         rerere();
 721         printf("Automatic merge failed; "
 722                         "fix conflicts and then commit the result.\n");
 723         return 1;
 724 }
 725
 726 static struct commit *is_old_style_invocation(int argc, const char **argv)
 727 {
 728         struct commit *second_token = NULL;
 729         if (argc > 1) {
 730                 unsigned char second_sha1[20];
 731
 732                 if (get_sha1(argv[1], second_sha1))
 733                         return NULL;
 734                 second_token = lookup_commit_reference_gently(second_sha1, 0);
 735                 if (!second_token)
 736                         die("'%s' is not a commit", argv[1]);
 737                 if (hashcmp(second_token->object.sha1, head))
 738                         return NULL;
 739         }
 740         return second_token;
 741 }
 742
 743 static int evaluate_result(void)
 744 {
 745         int cnt = 0;
 746         struct rev_info rev;
 747
 748         discard_cache();
 749         if (read_cache() < 0)
 750                 die("failed to read the cache");
 751
 752         /* Check how many files differ. */
 753         init_revisions(&rev, "");
 754         setup_revisions(0, NULL, &rev, NULL);
 755         rev.diffopt.output_format |=
 756                 DIFF_FORMAT_CALLBACK;
 757         rev.diffopt.format_callback = count_diff_files;
 758         rev.diffopt.format_callback_data = &cnt;
 759         run_diff_files(&rev, 0);
 760
 761         /*
 762          * Check how many unmerged entries are
 763          * there.
 764          */
 765         cnt += count_unmerged_entries();
 766
 767         return cnt;
 768 }
 769
 770 int cmd_merge(int argc, const char **argv, const char *prefix)
 771 {
 772         unsigned char result_tree[20];
 773         struct strbuf buf;
 774         const char *head_arg;
 775         int flag, head_invalid = 0, i;
 776         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
 777         struct commit_list *common = NULL;
 778         const char *best_strategy = NULL, *wt_strategy = NULL;
 779         struct commit_list **remotes = &remoteheads;
 780
 781         setup_work_tree();
 782         if (read_cache_unmerged())
 783                 die("You are in the middle of a conflicted merge.");
 784
 785         /*
 786          * Check if we are _not_ on a detached HEAD, i.e. if there is a
 787          * current branch.
 788          */
 789         branch = resolve_ref("HEAD", head, 0, &flag);
 790         if (branch && !prefixcmp(branch, "refs/heads/"))
 791                 branch += 11;
 792         if (is_null_sha1(head))
 793                 head_invalid = 1;
 794
 795         git_config(git_merge_config, NULL);
 796
 797         /* for color.ui */
 798         if (diff_use_color_default == -1)
 799                 diff_use_color_default = git_use_color_default;
 800
 801         argc = parse_options(argc, argv, builtin_merge_options,
 802                         builtin_merge_usage, 0);
 803
 804         if (squash) {
 805                 if (!allow_fast_forward)
 806                         die("You cannot combine --squash with --no-ff.");
 807                 option_commit = 0;
 808         }
 809
 810         if (!argc)
 811                 usage_with_options(builtin_merge_usage,
 812                         builtin_merge_options);
 813
 814         /*
 815          * This could be traditional "merge <msg> HEAD <commit>..."  and
 816          * the way we can tell it is to see if the second token is HEAD,
 817          * but some people might have misused the interface and used a
 818          * committish that is the same as HEAD there instead.
 819          * Traditional format never would have "-m" so it is an
 820          * additional safety measure to check for it.
 821          */
 822         strbuf_init(&buf, 0);
 823
 824         if (!have_message && is_old_style_invocation(argc, argv)) {
 825                 strbuf_addstr(&merge_msg, argv[0]);
 826                 head_arg = argv[1];
 827                 argv += 2;
 828                 argc -= 2;
 829         } else if (head_invalid) {
 830                 struct object *remote_head;
 831                 /*
 832                  * If the merged head is a valid one there is no reason
 833                  * to forbid "git merge" into a branch yet to be born.
 834                  * We do the same for "git pull".
 835                  */
 836                 if (argc != 1)
 837                         die("Can merge only exactly one commit into "
 838                                 "empty head");
 839                 remote_head = peel_to_type(argv[0], 0, NULL, OBJ_COMMIT);
 840                 if (!remote_head)
 841                         die("%s - not something we can merge", argv[0]);
 842                 update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
 843                                 DIE_ON_ERR);
 844                 reset_hard(remote_head->sha1, 0);
 845                 return 0;
 846         } else {
 847                 struct strbuf msg;
 848
 849                 /* We are invoked directly as the first-class UI. */
 850                 head_arg = "HEAD";
 851
 852                 /*
 853                  * All the rest are the commits being merged;
 854                  * prepare the standard merge summary message to
 855                  * be appended to the given message.  If remote
 856                  * is invalid we will die later in the common
 857                  * codepath so we discard the error in this
 858                  * loop.
 859                  */
 860                 strbuf_init(&msg, 0);
 861                 for (i = 0; i < argc; i++)
 862                         merge_name(argv[i], &msg);
 863                 fmt_merge_msg(option_log, &msg, &merge_msg);
 864                 if (merge_msg.len)
 865                         strbuf_setlen(&merge_msg, merge_msg.len-1);
 866         }
 867
 868         if (head_invalid || !argc)
 869                 usage_with_options(builtin_merge_usage,
 870                         builtin_merge_options);
 871
 872         strbuf_addstr(&buf, "merge");
 873         for (i = 0; i < argc; i++)
 874                 strbuf_addf(&buf, " %s", argv[i]);
 875         setenv("GIT_REFLOG_ACTION", buf.buf, 0);
 876         strbuf_reset(&buf);
 877
 878         for (i = 0; i < argc; i++) {
 879                 struct object *o;
 880
 881                 o = peel_to_type(argv[i], 0, NULL, OBJ_COMMIT);
 882                 if (!o)
 883                         die("%s - not something we can merge", argv[i]);
 884                 remotes = &commit_list_insert(lookup_commit(o->sha1),
 885                         remotes)->next;
 886
 887                 strbuf_addf(&buf, "GITHEAD_%s", sha1_to_hex(o->sha1));
 888                 setenv(buf.buf, argv[i], 1);
 889                 strbuf_reset(&buf);
 890         }
 891
 892         if (!use_strategies) {
 893                 if (!remoteheads->next)
 894                         add_strategies(pull_twohead, DEFAULT_TWOHEAD);
 895                 else
 896                         add_strategies(pull_octopus, DEFAULT_OCTOPUS);
 897         }
 898
 899         for (i = 0; i < use_strategies_nr; i++) {
 900                 if (use_strategies[i]->attr & NO_FAST_FORWARD)
 901                         allow_fast_forward = 0;
 902                 if (use_strategies[i]->attr & NO_TRIVIAL)
 903                         allow_trivial = 0;
 904         }
 905
 906         if (!remoteheads->next)
 907                 common = get_merge_bases(lookup_commit(head),
 908                                 remoteheads->item, 1);
 909         else {
 910                 struct commit_list *list = remoteheads;
 911                 commit_list_insert(lookup_commit(head), &list);
 912                 common = get_octopus_merge_bases(list);
 913                 free(list);
 914         }
 915
 916         update_ref("updating ORIG_HEAD", "ORIG_HEAD", head, NULL, 0,
 917                 DIE_ON_ERR);
 918
 919         if (!common)
 920                 ; /* No common ancestors found. We need a real merge. */
 921         else if (!remoteheads->next && !common->next &&
 922                         common->item == remoteheads->item) {
 923                 /*
 924                  * If head can reach all the merge then we are up to date.
 925                  * but first the most common case of merging one remote.
 926                  */
 927                 finish_up_to_date("Already up-to-date.");
 928                 return 0;
 929         } else if (allow_fast_forward && !remoteheads->next &&
 930                         !common->next &&
 931                         !hashcmp(common->item->object.sha1, head)) {
 932                 /* Again the most common case of merging one remote. */
 933                 struct strbuf msg;
 934                 struct object *o;
 935                 char hex[41];
 936
 937                 strcpy(hex, find_unique_abbrev(head, DEFAULT_ABBREV));
 938
 939                 printf("Updating %s..%s\n",
 940                         hex,
 941                         find_unique_abbrev(remoteheads->item->object.sha1,
 942                         DEFAULT_ABBREV));
 943                 strbuf_init(&msg, 0);
 944                 strbuf_addstr(&msg, "Fast forward");
 945                 if (have_message)
 946                         strbuf_addstr(&msg,
 947                                 " (no commit created; -m option ignored)");
 948                 o = peel_to_type(sha1_to_hex(remoteheads->item->object.sha1),
 949                         0, NULL, OBJ_COMMIT);
 950                 if (!o)
 951                         return 1;
 952
 953                 if (checkout_fast_forward(head, remoteheads->item->object.sha1))
 954                         return 1;
 955
 956                 finish(o->sha1, msg.buf);
 957                 drop_save();
 958                 return 0;
 959         } else if (!remoteheads->next && common->next)
 960                 ;
 961                 /*
 962                  * We are not doing octopus and not fast forward.  Need
 963                  * a real merge.
 964                  */
 965         else if (!remoteheads->next && !common->next && option_commit) {
 966                 /*
 967                  * We are not doing octopus, not fast forward, and have
 968                  * only one common.
 969                  */
 970                 refresh_cache(REFRESH_QUIET);
 971                 if (allow_trivial) {
 972                         /* See if it is really trivial. */
 973                         git_committer_info(IDENT_ERROR_ON_NO_NAME);
 974                         printf("Trying really trivial in-index merge...\n");
 975                         if (!read_tree_trivial(common->item->object.sha1,
 976                                         head, remoteheads->item->object.sha1))
 977                                 return merge_trivial();
 978                         printf("Nope.\n");
 979                 }
 980         } else {
 981                 /*
 982                  * An octopus.  If we can reach all the remote we are up
 983                  * to date.
 984                  */
 985                 int up_to_date = 1;
 986                 struct commit_list *j;
 987
 988                 for (j = remoteheads; j; j = j->next) {
 989                         struct commit_list *common_one;
 990
 991                         /*
 992                          * Here we *have* to calculate the individual
 993                          * merge_bases again, otherwise "git merge HEAD^
 994                          * HEAD^^" would be missed.
 995                          */
 996                         common_one = get_merge_bases(lookup_commit(head),
 997                                 j->item, 1);
 998                         if (hashcmp(common_one->item->object.sha1,
 999                                 j->item->object.sha1)) {
1000                                 up_to_date = 0;
1001                                 break;
1002                         }
1003                 }
1004                 if (up_to_date) {
1005                         finish_up_to_date("Already up-to-date. Yeeah!");
1006                         return 0;
1007                 }
1008         }
1009
1010         /* We are going to make a new commit. */
1011         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1012
1013         /*
1014          * At this point, we need a real merge.  No matter what strategy
1015          * we use, it would operate on the index, possibly affecting the
1016          * working tree, and when resolved cleanly, have the desired
1017          * tree in the index -- this means that the index must be in
1018          * sync with the head commit.  The strategies are responsible
1019          * to ensure this.
1020          */
1021         if (use_strategies_nr != 1) {
1022                 /*
1023                  * Stash away the local changes so that we can try more
1024                  * than one.
1025                  */
1026                 save_state();
1027         } else {
1028                 memcpy(stash, null_sha1, 20);
1029         }
1030
1031         for (i = 0; i < use_strategies_nr; i++) {
1032                 int ret;
1033                 if (i) {
1034                         printf("Rewinding the tree to pristine...\n");
1035                         restore_state();
1036                 }
1037                 if (use_strategies_nr != 1)
1038                         printf("Trying merge strategy %s...\n",
1039                                 use_strategies[i]->name);
1040                 /*
1041                  * Remember which strategy left the state in the working
1042                  * tree.
1043                  */
1044                 wt_strategy = use_strategies[i]->name;
1045
1046                 ret = try_merge_strategy(use_strategies[i]->name,
1047                         common, head_arg);
1048                 if (!option_commit && !ret) {
1049                         merge_was_ok = 1;
1050                         /*
1051                          * This is necessary here just to avoid writing
1052                          * the tree, but later we will *not* exit with
1053                          * status code 1 because merge_was_ok is set.
1054                          */
1055                         ret = 1;
1056                 }
1057
1058                 if (ret) {
1059                         /*
1060                          * The backend exits with 1 when conflicts are
1061                          * left to be resolved, with 2 when it does not
1062                          * handle the given merge at all.
1063                          */
1064                         if (ret == 1) {
1065                                 int cnt = evaluate_result();
1066
1067                                 if (best_cnt <= 0 || cnt <= best_cnt) {
1068                                         best_strategy = use_strategies[i]->name;
1069                                         best_cnt = cnt;
1070                                 }
1071                         }
1072                         if (merge_was_ok)
1073                                 break;
1074                         else
1075                                 continue;
1076                 }
1077
1078                 /* Automerge succeeded. */
1079                 discard_cache();
1080                 write_tree_trivial(result_tree);
1081                 automerge_was_ok = 1;
1082                 break;
1083         }
1084
1085         /*
1086          * If we have a resulting tree, that means the strategy module
1087          * auto resolved the merge cleanly.
1088          */
1089         if (automerge_was_ok)
1090                 return finish_automerge(common, result_tree, wt_strategy);
1091
1092         /*
1093          * Pick the result from the best strategy and have the user fix
1094          * it up.
1095          */
1096         if (!best_strategy) {
1097                 restore_state();
1098                 if (use_strategies_nr > 1)
1099                         fprintf(stderr,
1100                                 "No merge strategy handled the merge.\n");
1101                 else
1102                         fprintf(stderr, "Merge with strategy %s failed.\n",
1103                                 use_strategies[0]->name);
1104                 return 2;
1105         } else if (best_strategy == wt_strategy)
1106                 ; /* We already have its result in the working tree. */
1107         else {
1108                 printf("Rewinding the tree to pristine...\n");
1109                 restore_state();
1110                 printf("Using the %s to prepare resolving by hand.\n",
1111                         best_strategy);
1112                 try_merge_strategy(best_strategy, common, head_arg);
1113         }
1114
1115         if (squash)
1116                 finish(NULL, NULL);
1117         else {
1118                 int fd;
1119                 struct commit_list *j;
1120
1121                 for (j = remoteheads; j; j = j->next)
1122                         strbuf_addf(&buf, "%s\n",
1123                                 sha1_to_hex(j->item->object.sha1));
1124                 fd = open(git_path("MERGE_HEAD"), O_WRONLY | O_CREAT, 0666);
1125                 if (fd < 0)
1126                         die("Could open %s for writing",
1127                                 git_path("MERGE_HEAD"));
1128                 if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1129                         die("Could not write to %s", git_path("MERGE_HEAD"));
1130                 close(fd);
1131                 strbuf_addch(&merge_msg, '\n');
1132                 fd = open(git_path("MERGE_MSG"), O_WRONLY | O_CREAT, 0666);
1133                 if (fd < 0)
1134                         die("Could open %s for writing", git_path("MERGE_MSG"));
1135                 if (write_in_full(fd, merge_msg.buf, merge_msg.len) !=
1136                         merge_msg.len)
1137                         die("Could not write to %s", git_path("MERGE_MSG"));
1138                 close(fd);
1139         }
1140
1141         if (merge_was_ok) {
1142                 fprintf(stderr, "Automatic merge went well; "
1143                         "stopped before committing as requested\n");
1144                 return 0;
1145         } else
1146                 return suggest_conflicts();
1147 }