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
  81         if (!name)
  82                 return NULL;
  83
  84         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
  85                 if (!strcmp(name, all_strategy[i].name))
  86                         return &all_strategy[i];
  87         return NULL;
  88 }
  89
  90 static void append_strategy(struct strategy *s)
  91 {
  92         ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
  93         use_strategies[use_strategies_nr++] = s;
  94 }
  95
  96 static int option_parse_strategy(const struct option *opt,
  97                                  const char *name, int unset)
  98 {
  99         int i;
 100         struct strategy *s;
 101
 102         if (unset)
 103                 return 0;
 104
 105         s = get_strategy(name);
 106
 107         if (s)
 108                 append_strategy(s);
 109         else {
 110                 struct strbuf err;
 111                 strbuf_init(&err, 0);
 112                 for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 113                         strbuf_addf(&err, " %s", all_strategy[i].name);
 114                 fprintf(stderr, "Could not find merge strategy '%s'.\n", name);
 115                 fprintf(stderr, "Available strategies are:%s.\n", err.buf);
 116                 exit(1);
 117         }
 118         return 0;
 119 }
 120
 121 static int option_parse_n(const struct option *opt,
 122                           const char *arg, int unset)
 123 {
 124         show_diffstat = unset;
 125         return 0;
 126 }
 127
 128 static struct option builtin_merge_options[] = {
 129         { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
 130                 "do not show a diffstat at the end of the merge",
 131                 PARSE_OPT_NOARG, option_parse_n },
 132         OPT_BOOLEAN(0, "stat", &show_diffstat,
 133                 "show a diffstat at the end of the merge"),
 134         OPT_BOOLEAN(0, "summary", &show_diffstat, "(synonym to --stat)"),
 135         OPT_BOOLEAN(0, "log", &option_log,
 136                 "add list of one-line log to merge commit message"),
 137         OPT_BOOLEAN(0, "squash", &squash,
 138                 "create a single commit instead of doing a merge"),
 139         OPT_BOOLEAN(0, "commit", &option_commit,
 140                 "perform a commit if the merge succeeds (default)"),
 141         OPT_BOOLEAN(0, "ff", &allow_fast_forward,
 142                 "allow fast forward (default)"),
 143         OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
 144                 "merge strategy to use", option_parse_strategy),
 145         OPT_CALLBACK('m', "message", &merge_msg, "message",
 146                 "message to be used for the merge commit (if any)",
 147                 option_parse_message),
 148         OPT_END()
 149 };
 150
 151 /* Cleans up metadata that is uninteresting after a succeeded merge. */
 152 static void drop_save(void)
 153 {
 154         unlink(git_path("MERGE_HEAD"));
 155         unlink(git_path("MERGE_MSG"));
 156 }
 157
 158 static void save_state(void)
 159 {
 160         int len;
 161         struct child_process cp;
 162         struct strbuf buffer = STRBUF_INIT;
 163         const char *argv[] = {"stash", "create", NULL};
 164
 165         memset(&cp, 0, sizeof(cp));
 166         cp.argv = argv;
 167         cp.out = -1;
 168         cp.git_cmd = 1;
 169
 170         if (start_command(&cp))
 171                 die("could not run stash.");
 172         len = strbuf_read(&buffer, cp.out, 1024);
 173         close(cp.out);
 174
 175         if (finish_command(&cp) || len < 0)
 176                 die("stash failed");
 177         else if (!len)
 178                 return;
 179         strbuf_setlen(&buffer, buffer.len-1);
 180         if (get_sha1(buffer.buf, stash))
 181                 die("not a valid object: %s", buffer.buf);
 182 }
 183
 184 static void reset_hard(unsigned const char *sha1, int verbose)
 185 {
 186         int i = 0;
 187         const char *args[6];
 188
 189         args[i++] = "read-tree";
 190         if (verbose)
 191                 args[i++] = "-v";
 192         args[i++] = "--reset";
 193         args[i++] = "-u";
 194         args[i++] = sha1_to_hex(sha1);
 195         args[i] = NULL;
 196
 197         if (run_command_v_opt(args, RUN_GIT_CMD))
 198                 die("read-tree failed");
 199 }
 200
 201 static void restore_state(void)
 202 {
 203         struct strbuf sb;
 204         const char *args[] = { "stash", "apply", NULL, NULL };
 205
 206         if (is_null_sha1(stash))
 207                 return;
 208
 209         reset_hard(head, 1);
 210
 211         strbuf_init(&sb, 0);
 212         args[2] = sha1_to_hex(stash);
 213
 214         /*
 215          * It is OK to ignore error here, for example when there was
 216          * nothing to restore.
 217          */
 218         run_command_v_opt(args, RUN_GIT_CMD);
 219
 220         strbuf_release(&sb);
 221         refresh_cache(REFRESH_QUIET);
 222 }
 223
 224 /* This is called when no merge was necessary. */
 225 static void finish_up_to_date(const char *msg)
 226 {
 227         printf("%s%s\n", squash ? " (nothing to squash)" : "", msg);
 228         drop_save();
 229 }
 230
 231 static void squash_message(void)
 232 {
 233         struct rev_info rev;
 234         struct commit *commit;
 235         struct strbuf out;
 236         struct commit_list *j;
 237         int fd;
 238
 239         printf("Squash commit -- not updating HEAD\n");
 240         fd = open(git_path("SQUASH_MSG"), O_WRONLY | O_CREAT, 0666);
 241         if (fd < 0)
 242                 die("Could not write to %s", git_path("SQUASH_MSG"));
 243
 244         init_revisions(&rev, NULL);
 245         rev.ignore_merges = 1;
 246         rev.commit_format = CMIT_FMT_MEDIUM;
 247
 248         commit = lookup_commit(head);
 249         commit->object.flags |= UNINTERESTING;
 250         add_pending_object(&rev, &commit->object, NULL);
 251
 252         for (j = remoteheads; j; j = j->next)
 253                 add_pending_object(&rev, &j->item->object, NULL);
 254
 255         setup_revisions(0, NULL, &rev, NULL);
 256         if (prepare_revision_walk(&rev))
 257                 die("revision walk setup failed");
 258
 259         strbuf_init(&out, 0);
 260         strbuf_addstr(&out, "Squashed commit of the following:\n");
 261         while ((commit = get_revision(&rev)) != NULL) {
 262                 strbuf_addch(&out, '\n');
 263                 strbuf_addf(&out, "commit %s\n",
 264                         sha1_to_hex(commit->object.sha1));
 265                 pretty_print_commit(rev.commit_format, commit, &out, rev.abbrev,
 266                         NULL, NULL, rev.date_mode, 0);
 267         }
 268         write(fd, out.buf, out.len);
 269         close(fd);
 270         strbuf_release(&out);
 271 }
 272
 273 static int run_hook(const char *name)
 274 {
 275         struct child_process hook;
 276         const char *argv[3], *env[2];
 277         char index[PATH_MAX];
 278
 279         argv[0] = git_path("hooks/%s", name);
 280         if (access(argv[0], X_OK) < 0)
 281                 return 0;
 282
 283         snprintf(index, sizeof(index), "GIT_INDEX_FILE=%s", get_index_file());
 284         env[0] = index;
 285         env[1] = NULL;
 286
 287         if (squash)
 288                 argv[1] = "1";
 289         else
 290                 argv[1] = "0";
 291         argv[2] = NULL;
 292
 293         memset(&hook, 0, sizeof(hook));
 294         hook.argv = argv;
 295         hook.no_stdin = 1;
 296         hook.stdout_to_stderr = 1;
 297         hook.env = env;
 298
 299         return run_command(&hook);
 300 }
 301
 302 static void finish(const unsigned char *new_head, const char *msg)
 303 {
 304         struct strbuf reflog_message;
 305
 306         strbuf_init(&reflog_message, 0);
 307         if (!msg)
 308                 strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
 309         else {
 310                 printf("%s\n", msg);
 311                 strbuf_addf(&reflog_message, "%s: %s",
 312                         getenv("GIT_REFLOG_ACTION"), msg);
 313         }
 314         if (squash) {
 315                 squash_message();
 316         } else {
 317                 if (!merge_msg.len)
 318                         printf("No merge message -- not updating HEAD\n");
 319                 else {
 320                         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 321                         update_ref(reflog_message.buf, "HEAD",
 322                                 new_head, head, 0,
 323                                 DIE_ON_ERR);
 324                         /*
 325                          * We ignore errors in 'gc --auto', since the
 326                          * user should see them.
 327                          */
 328                         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 329                 }
 330         }
 331         if (new_head && show_diffstat) {
 332                 struct diff_options opts;
 333                 diff_setup(&opts);
 334                 opts.output_format |=
 335                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 336                 opts.detect_rename = DIFF_DETECT_RENAME;
 337                 if (diff_use_color_default > 0)
 338                         DIFF_OPT_SET(&opts, COLOR_DIFF);
 339                 if (diff_setup_done(&opts) < 0)
 340                         die("diff_setup_done failed");
 341                 diff_tree_sha1(head, new_head, "", &opts);
 342                 diffcore_std(&opts);
 343                 diff_flush(&opts);
 344         }
 345
 346         /* Run a post-merge hook */
 347         run_hook("post-merge");
 348
 349         strbuf_release(&reflog_message);
 350 }
 351
 352 /* Get the name for the merge commit's message. */
 353 static void merge_name(const char *remote, struct strbuf *msg)
 354 {
 355         struct object *remote_head;
 356         unsigned char branch_head[20], buf_sha[20];
 357         struct strbuf buf;
 358         const char *ptr;
 359         int len, early;
 360
 361         memset(branch_head, 0, sizeof(branch_head));
 362         remote_head = peel_to_type(remote, 0, NULL, OBJ_COMMIT);
 363         if (!remote_head)
 364                 die("'%s' does not point to a commit", remote);
 365
 366         strbuf_init(&buf, 0);
 367         strbuf_addstr(&buf, "refs/heads/");
 368         strbuf_addstr(&buf, remote);
 369         resolve_ref(buf.buf, branch_head, 0, 0);
 370
 371         if (!hashcmp(remote_head->sha1, branch_head)) {
 372                 strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
 373                         sha1_to_hex(branch_head), remote);
 374                 return;
 375         }
 376
 377         /* See if remote matches <name>^^^.. or <name>~<number> */
 378         for (len = 0, ptr = remote + strlen(remote);
 379              remote < ptr && ptr[-1] == '^';
 380              ptr--)
 381                 len++;
 382         if (len)
 383                 early = 1;
 384         else {
 385                 early = 0;
 386                 ptr = strrchr(remote, '~');
 387                 if (ptr) {
 388                         int seen_nonzero = 0;
 389
 390                         len++; /* count ~ */
 391                         while (*++ptr && isdigit(*ptr)) {
 392                                 seen_nonzero |= (*ptr != '0');
 393                                 len++;
 394                         }
 395                         if (*ptr)
 396                                 len = 0; /* not ...~<number> */
 397                         else if (seen_nonzero)
 398                                 early = 1;
 399                         else if (len == 1)
 400                                 early = 1; /* "name~" is "name~1"! */
 401                 }
 402         }
 403         if (len) {
 404                 struct strbuf truname = STRBUF_INIT;
 405                 strbuf_addstr(&truname, "refs/heads/");
 406                 strbuf_addstr(&truname, remote);
 407                 strbuf_setlen(&truname, len+11);
 408                 if (resolve_ref(truname.buf, buf_sha, 0, 0)) {
 409                         strbuf_addf(msg,
 410                                     "%s\t\tbranch '%s'%s of .\n",
 411                                     sha1_to_hex(remote_head->sha1),
 412                                     truname.buf,
 413                                     (early ? " (early part)" : ""));
 414                         return;
 415                 }
 416         }
 417
 418         if (!strcmp(remote, "FETCH_HEAD") &&
 419                         !access(git_path("FETCH_HEAD"), R_OK)) {
 420                 FILE *fp;
 421                 struct strbuf line;
 422                 char *ptr;
 423
 424                 strbuf_init(&line, 0);
 425                 fp = fopen(git_path("FETCH_HEAD"), "r");
 426                 if (!fp)
 427                         die("could not open %s for reading: %s",
 428                                 git_path("FETCH_HEAD"), strerror(errno));
 429                 strbuf_getline(&line, fp, '\n');
 430                 fclose(fp);
 431                 ptr = strstr(line.buf, "\tnot-for-merge\t");
 432                 if (ptr)
 433                         strbuf_remove(&line, ptr-line.buf+1, 13);
 434                 strbuf_addbuf(msg, &line);
 435                 strbuf_release(&line);
 436                 return;
 437         }
 438         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
 439                 sha1_to_hex(remote_head->sha1), remote);
 440 }
 441
 442 int git_merge_config(const char *k, const char *v, void *cb)
 443 {
 444         if (branch && !prefixcmp(k, "branch.") &&
 445                 !prefixcmp(k + 7, branch) &&
 446                 !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
 447                 const char **argv;
 448                 int argc;
 449                 char *buf;
 450
 451                 buf = xstrdup(v);
 452                 argc = split_cmdline(buf, &argv);
 453                 argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
 454                 memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
 455                 argc++;
 456                 parse_options(argc, argv, builtin_merge_options,
 457                               builtin_merge_usage, 0);
 458                 free(buf);
 459         }
 460
 461         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
 462                 show_diffstat = git_config_bool(k, v);
 463         else if (!strcmp(k, "pull.twohead"))
 464                 return git_config_string(&pull_twohead, k, v);
 465         else if (!strcmp(k, "pull.octopus"))
 466                 return git_config_string(&pull_octopus, k, v);
 467         else if (!strcmp(k, "merge.log") || !strcmp(k, "merge.summary"))
 468                 option_log = git_config_bool(k, v);
 469         return git_diff_ui_config(k, v, cb);
 470 }
 471
 472 static int read_tree_trivial(unsigned char *common, unsigned char *head,
 473                              unsigned char *one)
 474 {
 475         int i, nr_trees = 0;
 476         struct tree *trees[MAX_UNPACK_TREES];
 477         struct tree_desc t[MAX_UNPACK_TREES];
 478         struct unpack_trees_options opts;
 479
 480         memset(&opts, 0, sizeof(opts));
 481         opts.head_idx = 2;
 482         opts.src_index = &the_index;
 483         opts.dst_index = &the_index;
 484         opts.update = 1;
 485         opts.verbose_update = 1;
 486         opts.trivial_merges_only = 1;
 487         opts.merge = 1;
 488         trees[nr_trees] = parse_tree_indirect(common);
 489         if (!trees[nr_trees++])
 490                 return -1;
 491         trees[nr_trees] = parse_tree_indirect(head);
 492         if (!trees[nr_trees++])
 493                 return -1;
 494         trees[nr_trees] = parse_tree_indirect(one);
 495         if (!trees[nr_trees++])
 496                 return -1;
 497         opts.fn = threeway_merge;
 498         cache_tree_free(&active_cache_tree);
 499         for (i = 0; i < nr_trees; i++) {
 500                 parse_tree(trees[i]);
 501                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 502         }
 503         if (unpack_trees(nr_trees, t, &opts))
 504                 return -1;
 505         return 0;
 506 }
 507
 508 static void write_tree_trivial(unsigned char *sha1)
 509 {
 510         if (write_cache_as_tree(sha1, 0, NULL))
 511                 die("git write-tree failed to write a tree");
 512 }
 513
 514 static int try_merge_strategy(const char *strategy, struct commit_list *common,
 515                               const char *head_arg)
 516 {
 517         const char **args;
 518         int i = 0, ret;
 519         struct commit_list *j;
 520         struct strbuf buf;
 521
 522         args = xmalloc((4 + commit_list_count(common) +
 523                         commit_list_count(remoteheads)) * sizeof(char *));
 524         strbuf_init(&buf, 0);
 525         strbuf_addf(&buf, "merge-%s", strategy);
 526         args[i++] = buf.buf;
 527         for (j = common; j; j = j->next)
 528                 args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
 529         args[i++] = "--";
 530         args[i++] = head_arg;
 531         for (j = remoteheads; j; j = j->next)
 532                 args[i++] = xstrdup(sha1_to_hex(j->item->object.sha1));
 533         args[i] = NULL;
 534         ret = run_command_v_opt(args, RUN_GIT_CMD);
 535         strbuf_release(&buf);
 536         i = 1;
 537         for (j = common; j; j = j->next)
 538                 free((void *)args[i++]);
 539         i += 2;
 540         for (j = remoteheads; j; j = j->next)
 541                 free((void *)args[i++]);
 542         free(args);
 543         return -ret;
 544 }
 545
 546 static void count_diff_files(struct diff_queue_struct *q,
 547                              struct diff_options *opt, void *data)
 548 {
 549         int *count = data;
 550
 551         (*count) += q->nr;
 552 }
 553
 554 static int count_unmerged_entries(void)
 555 {
 556         const struct index_state *state = &the_index;
 557         int i, ret = 0;
 558
 559         for (i = 0; i < state->cache_nr; i++)
 560                 if (ce_stage(state->cache[i]))
 561                         ret++;
 562
 563         return ret;
 564 }
 565
 566 static int checkout_fast_forward(unsigned char *head, unsigned char *remote)
 567 {
 568         struct tree *trees[MAX_UNPACK_TREES];
 569         struct unpack_trees_options opts;
 570         struct tree_desc t[MAX_UNPACK_TREES];
 571         int i, fd, nr_trees = 0;
 572         struct dir_struct dir;
 573         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 574
 575         if (read_cache_unmerged())
 576                 die("you need to resolve your current index first");
 577
 578         fd = hold_locked_index(lock_file, 1);
 579
 580         memset(&trees, 0, sizeof(trees));
 581         memset(&opts, 0, sizeof(opts));
 582         memset(&t, 0, sizeof(t));
 583         dir.show_ignored = 1;
 584         dir.exclude_per_dir = ".gitignore";
 585         opts.dir = &dir;
 586
 587         opts.head_idx = 1;
 588         opts.src_index = &the_index;
 589         opts.dst_index = &the_index;
 590         opts.update = 1;
 591         opts.verbose_update = 1;
 592         opts.merge = 1;
 593         opts.fn = twoway_merge;
 594
 595         trees[nr_trees] = parse_tree_indirect(head);
 596         if (!trees[nr_trees++])
 597                 return -1;
 598         trees[nr_trees] = parse_tree_indirect(remote);
 599         if (!trees[nr_trees++])
 600                 return -1;
 601         for (i = 0; i < nr_trees; i++) {
 602                 parse_tree(trees[i]);
 603                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 604         }
 605         if (unpack_trees(nr_trees, t, &opts))
 606                 return -1;
 607         if (write_cache(fd, active_cache, active_nr) ||
 608                 commit_locked_index(lock_file))
 609                 die("unable to write new index file");
 610         return 0;
 611 }
 612
 613 static void split_merge_strategies(const char *string, struct strategy **list,
 614                                    int *nr, int *alloc)
 615 {
 616         char *p, *q, *buf;
 617
 618         if (!string)
 619                 return;
 620
 621         buf = xstrdup(string);
 622         q = buf;
 623         for (;;) {
 624                 p = strchr(q, ' ');
 625                 if (!p) {
 626                         ALLOC_GROW(*list, *nr + 1, *alloc);
 627                         (*list)[(*nr)++].name = xstrdup(q);
 628                         free(buf);
 629                         return;
 630                 } else {
 631                         *p = '\0';
 632                         ALLOC_GROW(*list, *nr + 1, *alloc);
 633                         (*list)[(*nr)++].name = xstrdup(q);
 634                         q = ++p;
 635                 }
 636         }
 637 }
 638
 639 static void add_strategies(const char *string, unsigned attr)
 640 {
 641         struct strategy *list = NULL;
 642         int list_alloc = 0, list_nr = 0, i;
 643
 644         memset(&list, 0, sizeof(list));
 645         split_merge_strategies(string, &list, &list_nr, &list_alloc);
 646         if (list != NULL) {
 647                 for (i = 0; i < list_nr; i++) {
 648                         struct strategy *s;
 649
 650                         s = get_strategy(list[i].name);
 651                         if (s)
 652                                 append_strategy(s);
 653                 }
 654                 return;
 655         }
 656         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 657                 if (all_strategy[i].attr & attr)
 658                         append_strategy(&all_strategy[i]);
 659
 660 }
 661
 662 static int merge_trivial(void)
 663 {
 664         unsigned char result_tree[20], result_commit[20];
 665         struct commit_list parent;
 666
 667         write_tree_trivial(result_tree);
 668         printf("Wonderful.\n");
 669         parent.item = remoteheads->item;
 670         parent.next = NULL;
 671         commit_tree(merge_msg.buf, result_tree, &parent, result_commit);
 672         finish(result_commit, "In-index merge");
 673         drop_save();
 674         return 0;
 675 }
 676
 677 static int finish_automerge(struct commit_list *common,
 678                             unsigned char *result_tree,
 679                             const char *wt_strategy)
 680 {
 681         struct commit_list *parents = NULL, *j;
 682         struct strbuf buf = STRBUF_INIT;
 683         unsigned char result_commit[20];
 684
 685         free_commit_list(common);
 686         if (allow_fast_forward) {
 687                 parents = remoteheads;
 688                 commit_list_insert(lookup_commit(head), &parents);
 689                 parents = reduce_heads(parents);
 690         } else {
 691                 struct commit_list **pptr = &parents;
 692
 693                 pptr = &commit_list_insert(lookup_commit(head),
 694                                 pptr)->next;
 695                 for (j = remoteheads; j; j = j->next)
 696                         pptr = &commit_list_insert(j->item, pptr)->next;
 697         }
 698         free_commit_list(remoteheads);
 699         strbuf_addch(&merge_msg, '\n');
 700         commit_tree(merge_msg.buf, result_tree, parents, result_commit);
 701         strbuf_addf(&buf, "Merge made by %s.", wt_strategy);
 702         finish(result_commit, buf.buf);
 703         strbuf_release(&buf);
 704         drop_save();
 705         return 0;
 706 }
 707
 708 static int suggest_conflicts(void)
 709 {
 710         FILE *fp;
 711         int pos;
 712
 713         fp = fopen(git_path("MERGE_MSG"), "a");
 714         if (!fp)
 715                 die("Could open %s for writing", git_path("MERGE_MSG"));
 716         fprintf(fp, "\nConflicts:\n");
 717         for (pos = 0; pos < active_nr; pos++) {
 718                 struct cache_entry *ce = active_cache[pos];
 719
 720                 if (ce_stage(ce)) {
 721                         fprintf(fp, "\t%s\n", ce->name);
 722                         while (pos + 1 < active_nr &&
 723                                         !strcmp(ce->name,
 724                                                 active_cache[pos + 1]->name))
 725                                 pos++;
 726                 }
 727         }
 728         fclose(fp);
 729         rerere();
 730         printf("Automatic merge failed; "
 731                         "fix conflicts and then commit the result.\n");
 732         return 1;
 733 }
 734
 735 static struct commit *is_old_style_invocation(int argc, const char **argv)
 736 {
 737         struct commit *second_token = NULL;
 738         if (argc > 1) {
 739                 unsigned char second_sha1[20];
 740
 741                 if (get_sha1(argv[1], second_sha1))
 742                         return NULL;
 743                 second_token = lookup_commit_reference_gently(second_sha1, 0);
 744                 if (!second_token)
 745                         die("'%s' is not a commit", argv[1]);
 746                 if (hashcmp(second_token->object.sha1, head))
 747                         return NULL;
 748         }
 749         return second_token;
 750 }
 751
 752 static int evaluate_result(void)
 753 {
 754         int cnt = 0;
 755         struct rev_info rev;
 756
 757         if (read_cache() < 0)
 758                 die("failed to read the cache");
 759
 760         /* Check how many files differ. */
 761         init_revisions(&rev, "");
 762         setup_revisions(0, NULL, &rev, NULL);
 763         rev.diffopt.output_format |=
 764                 DIFF_FORMAT_CALLBACK;
 765         rev.diffopt.format_callback = count_diff_files;
 766         rev.diffopt.format_callback_data = &cnt;
 767         run_diff_files(&rev, 0);
 768
 769         /*
 770          * Check how many unmerged entries are
 771          * there.
 772          */
 773         cnt += count_unmerged_entries();
 774
 775         return cnt;
 776 }
 777
 778 int cmd_merge(int argc, const char **argv, const char *prefix)
 779 {
 780         unsigned char result_tree[20];
 781         struct strbuf buf;
 782         const char *head_arg;
 783         int flag, head_invalid = 0, i;
 784         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
 785         struct commit_list *common = NULL;
 786         const char *best_strategy = NULL, *wt_strategy = NULL;
 787         struct commit_list **remotes = &remoteheads;
 788
 789         setup_work_tree();
 790         if (unmerged_cache())
 791                 die("You are in the middle of a conflicted merge.");
 792
 793         /*
 794          * Check if we are _not_ on a detached HEAD, i.e. if there is a
 795          * current branch.
 796          */
 797         branch = resolve_ref("HEAD", head, 0, &flag);
 798         if (branch && !prefixcmp(branch, "refs/heads/"))
 799                 branch += 11;
 800         if (is_null_sha1(head))
 801                 head_invalid = 1;
 802
 803         git_config(git_merge_config, NULL);
 804
 805         /* for color.ui */
 806         if (diff_use_color_default == -1)
 807                 diff_use_color_default = git_use_color_default;
 808
 809         argc = parse_options(argc, argv, builtin_merge_options,
 810                         builtin_merge_usage, 0);
 811
 812         if (squash) {
 813                 if (!allow_fast_forward)
 814                         die("You cannot combine --squash with --no-ff.");
 815                 option_commit = 0;
 816         }
 817
 818         if (!argc)
 819                 usage_with_options(builtin_merge_usage,
 820                         builtin_merge_options);
 821
 822         /*
 823          * This could be traditional "merge <msg> HEAD <commit>..."  and
 824          * the way we can tell it is to see if the second token is HEAD,
 825          * but some people might have misused the interface and used a
 826          * committish that is the same as HEAD there instead.
 827          * Traditional format never would have "-m" so it is an
 828          * additional safety measure to check for it.
 829          */
 830         strbuf_init(&buf, 0);
 831
 832         if (!have_message && is_old_style_invocation(argc, argv)) {
 833                 strbuf_addstr(&merge_msg, argv[0]);
 834                 head_arg = argv[1];
 835                 argv += 2;
 836                 argc -= 2;
 837         } else if (head_invalid) {
 838                 struct object *remote_head;
 839                 /*
 840                  * If the merged head is a valid one there is no reason
 841                  * to forbid "git merge" into a branch yet to be born.
 842                  * We do the same for "git pull".
 843                  */
 844                 if (argc != 1)
 845                         die("Can merge only exactly one commit into "
 846                                 "empty head");
 847                 remote_head = peel_to_type(argv[0], 0, NULL, OBJ_COMMIT);
 848                 if (!remote_head)
 849                         die("%s - not something we can merge", argv[0]);
 850                 update_ref("initial pull", "HEAD", remote_head->sha1, NULL, 0,
 851                                 DIE_ON_ERR);
 852                 reset_hard(remote_head->sha1, 0);
 853                 return 0;
 854         } else {
 855                 struct strbuf msg;
 856
 857                 /* We are invoked directly as the first-class UI. */
 858                 head_arg = "HEAD";
 859
 860                 /*
 861                  * All the rest are the commits being merged;
 862                  * prepare the standard merge summary message to
 863                  * be appended to the given message.  If remote
 864                  * is invalid we will die later in the common
 865                  * codepath so we discard the error in this
 866                  * loop.
 867                  */
 868                 strbuf_init(&msg, 0);
 869                 for (i = 0; i < argc; i++)
 870                         merge_name(argv[i], &msg);
 871                 fmt_merge_msg(option_log, &msg, &merge_msg);
 872                 if (merge_msg.len)
 873                         strbuf_setlen(&merge_msg, merge_msg.len-1);
 874         }
 875
 876         if (head_invalid || !argc)
 877                 usage_with_options(builtin_merge_usage,
 878                         builtin_merge_options);
 879
 880         strbuf_addstr(&buf, "merge");
 881         for (i = 0; i < argc; i++)
 882                 strbuf_addf(&buf, " %s", argv[i]);
 883         setenv("GIT_REFLOG_ACTION", buf.buf, 0);
 884         strbuf_reset(&buf);
 885
 886         for (i = 0; i < argc; i++) {
 887                 struct object *o;
 888
 889                 o = peel_to_type(argv[i], 0, NULL, OBJ_COMMIT);
 890                 if (!o)
 891                         die("%s - not something we can merge", argv[i]);
 892                 remotes = &commit_list_insert(lookup_commit(o->sha1),
 893                         remotes)->next;
 894
 895                 strbuf_addf(&buf, "GITHEAD_%s", sha1_to_hex(o->sha1));
 896                 setenv(buf.buf, argv[i], 1);
 897                 strbuf_reset(&buf);
 898         }
 899
 900         if (!use_strategies) {
 901                 if (!remoteheads->next)
 902                         add_strategies(pull_twohead, DEFAULT_TWOHEAD);
 903                 else
 904                         add_strategies(pull_octopus, DEFAULT_OCTOPUS);
 905         }
 906
 907         for (i = 0; i < use_strategies_nr; i++) {
 908                 if (use_strategies[i]->attr & NO_FAST_FORWARD)
 909                         allow_fast_forward = 0;
 910                 if (use_strategies[i]->attr & NO_TRIVIAL)
 911                         allow_trivial = 0;
 912         }
 913
 914         if (!remoteheads->next)
 915                 common = get_merge_bases(lookup_commit(head),
 916                                 remoteheads->item, 1);
 917         else {
 918                 struct commit_list *list = remoteheads;
 919                 commit_list_insert(lookup_commit(head), &list);
 920                 common = get_octopus_merge_bases(list);
 921                 free(list);
 922         }
 923
 924         update_ref("updating ORIG_HEAD", "ORIG_HEAD", head, NULL, 0,
 925                 DIE_ON_ERR);
 926
 927         if (!common)
 928                 ; /* No common ancestors found. We need a real merge. */
 929         else if (!remoteheads->next && !common->next &&
 930                         common->item == remoteheads->item) {
 931                 /*
 932                  * If head can reach all the merge then we are up to date.
 933                  * but first the most common case of merging one remote.
 934                  */
 935                 finish_up_to_date("Already up-to-date.");
 936                 return 0;
 937         } else if (allow_fast_forward && !remoteheads->next &&
 938                         !common->next &&
 939                         !hashcmp(common->item->object.sha1, head)) {
 940                 /* Again the most common case of merging one remote. */
 941                 struct strbuf msg;
 942                 struct object *o;
 943                 char hex[41];
 944
 945                 strcpy(hex, find_unique_abbrev(head, DEFAULT_ABBREV));
 946
 947                 printf("Updating %s..%s\n",
 948                         hex,
 949                         find_unique_abbrev(remoteheads->item->object.sha1,
 950                         DEFAULT_ABBREV));
 951                 refresh_cache(REFRESH_QUIET);
 952                 strbuf_init(&msg, 0);
 953                 strbuf_addstr(&msg, "Fast forward");
 954                 if (have_message)
 955                         strbuf_addstr(&msg,
 956                                 " (no commit created; -m option ignored)");
 957                 o = peel_to_type(sha1_to_hex(remoteheads->item->object.sha1),
 958                         0, NULL, OBJ_COMMIT);
 959                 if (!o)
 960                         return 1;
 961
 962                 if (checkout_fast_forward(head, remoteheads->item->object.sha1))
 963                         return 1;
 964
 965                 finish(o->sha1, msg.buf);
 966                 drop_save();
 967                 return 0;
 968         } else if (!remoteheads->next && common->next)
 969                 ;
 970                 /*
 971                  * We are not doing octopus and not fast forward.  Need
 972                  * a real merge.
 973                  */
 974         else if (!remoteheads->next && !common->next && option_commit) {
 975                 /*
 976                  * We are not doing octopus, not fast forward, and have
 977                  * only one common.
 978                  */
 979                 refresh_cache(REFRESH_QUIET);
 980                 if (allow_trivial) {
 981                         /* See if it is really trivial. */
 982                         git_committer_info(IDENT_ERROR_ON_NO_NAME);
 983                         printf("Trying really trivial in-index merge...\n");
 984                         if (!read_tree_trivial(common->item->object.sha1,
 985                                         head, remoteheads->item->object.sha1))
 986                                 return merge_trivial();
 987                         printf("Nope.\n");
 988                 }
 989         } else {
 990                 /*
 991                  * An octopus.  If we can reach all the remote we are up
 992                  * to date.
 993                  */
 994                 int up_to_date = 1;
 995                 struct commit_list *j;
 996
 997                 for (j = remoteheads; j; j = j->next) {
 998                         struct commit_list *common_one;
 999
1000                         /*
1001                          * Here we *have* to calculate the individual
1002                          * merge_bases again, otherwise "git merge HEAD^
1003                          * HEAD^^" would be missed.
1004                          */
1005                         common_one = get_merge_bases(lookup_commit(head),
1006                                 j->item, 1);
1007                         if (hashcmp(common_one->item->object.sha1,
1008                                 j->item->object.sha1)) {
1009                                 up_to_date = 0;
1010                                 break;
1011                         }
1012                 }
1013                 if (up_to_date) {
1014                         finish_up_to_date("Already up-to-date. Yeeah!");
1015                         return 0;
1016                 }
1017         }
1018
1019         /* We are going to make a new commit. */
1020         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1021
1022         /*
1023          * At this point, we need a real merge.  No matter what strategy
1024          * we use, it would operate on the index, possibly affecting the
1025          * working tree, and when resolved cleanly, have the desired
1026          * tree in the index -- this means that the index must be in
1027          * sync with the head commit.  The strategies are responsible
1028          * to ensure this.
1029          */
1030         if (use_strategies_nr != 1) {
1031                 /*
1032                  * Stash away the local changes so that we can try more
1033                  * than one.
1034                  */
1035                 save_state();
1036         } else {
1037                 memcpy(stash, null_sha1, 20);
1038         }
1039
1040         for (i = 0; i < use_strategies_nr; i++) {
1041                 int ret;
1042                 if (i) {
1043                         printf("Rewinding the tree to pristine...\n");
1044                         restore_state();
1045                 }
1046                 if (use_strategies_nr != 1)
1047                         printf("Trying merge strategy %s...\n",
1048                                 use_strategies[i]->name);
1049                 /*
1050                  * Remember which strategy left the state in the working
1051                  * tree.
1052                  */
1053                 wt_strategy = use_strategies[i]->name;
1054
1055                 ret = try_merge_strategy(use_strategies[i]->name,
1056                         common, head_arg);
1057                 if (!option_commit && !ret) {
1058                         merge_was_ok = 1;
1059                         /*
1060                          * This is necessary here just to avoid writing
1061                          * the tree, but later we will *not* exit with
1062                          * status code 1 because merge_was_ok is set.
1063                          */
1064                         ret = 1;
1065                 }
1066
1067                 if (ret) {
1068                         /*
1069                          * The backend exits with 1 when conflicts are
1070                          * left to be resolved, with 2 when it does not
1071                          * handle the given merge at all.
1072                          */
1073                         if (ret == 1) {
1074                                 int cnt = evaluate_result();
1075
1076                                 if (best_cnt <= 0 || cnt <= best_cnt) {
1077                                         best_strategy = use_strategies[i]->name;
1078                                         best_cnt = cnt;
1079                                 }
1080                         }
1081                         if (merge_was_ok)
1082                                 break;
1083                         else
1084                                 continue;
1085                 }
1086
1087                 /* Automerge succeeded. */
1088                 write_tree_trivial(result_tree);
1089                 automerge_was_ok = 1;
1090                 break;
1091         }
1092
1093         /*
1094          * If we have a resulting tree, that means the strategy module
1095          * auto resolved the merge cleanly.
1096          */
1097         if (automerge_was_ok)
1098                 return finish_automerge(common, result_tree, wt_strategy);
1099
1100         /*
1101          * Pick the result from the best strategy and have the user fix
1102          * it up.
1103          */
1104         if (!best_strategy) {
1105                 restore_state();
1106                 if (use_strategies_nr > 1)
1107                         fprintf(stderr,
1108                                 "No merge strategy handled the merge.\n");
1109                 else
1110                         fprintf(stderr, "Merge with strategy %s failed.\n",
1111                                 use_strategies[0]->name);
1112                 return 2;
1113         } else if (best_strategy == wt_strategy)
1114                 ; /* We already have its result in the working tree. */
1115         else {
1116                 printf("Rewinding the tree to pristine...\n");
1117                 restore_state();
1118                 printf("Using the %s to prepare resolving by hand.\n",
1119                         best_strategy);
1120                 try_merge_strategy(best_strategy, common, head_arg);
1121         }
1122
1123         if (squash)
1124                 finish(NULL, NULL);
1125         else {
1126                 int fd;
1127                 struct commit_list *j;
1128
1129                 for (j = remoteheads; j; j = j->next)
1130                         strbuf_addf(&buf, "%s\n",
1131                                 sha1_to_hex(j->item->object.sha1));
1132                 fd = open(git_path("MERGE_HEAD"), O_WRONLY | O_CREAT, 0666);
1133                 if (fd < 0)
1134                         die("Could open %s for writing",
1135                                 git_path("MERGE_HEAD"));
1136                 if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1137                         die("Could not write to %s", git_path("MERGE_HEAD"));
1138                 close(fd);
1139                 strbuf_addch(&merge_msg, '\n');
1140                 fd = open(git_path("MERGE_MSG"), O_WRONLY | O_CREAT, 0666);
1141                 if (fd < 0)
1142                         die("Could open %s for writing", git_path("MERGE_MSG"));
1143                 if (write_in_full(fd, merge_msg.buf, merge_msg.len) !=
1144                         merge_msg.len)
1145                         die("Could not write to %s", git_path("MERGE_MSG"));
1146                 close(fd);
1147         }
1148
1149         if (merge_was_ok) {
1150                 fprintf(stderr, "Automatic merge went well; "
1151                         "stopped before committing as requested\n");
1152                 return 0;
1153         } else
1154                 return suggest_conflicts();
1155 }