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 #include "help.h"
  26 #include "merge-recursive.h"
  27 #include "resolve-undo.h"
  28 #include "remote.h"
  29 #include "fmt-merge-msg.h"
  30 #include "gpg-interface.h"
  31
  32 #define DEFAULT_TWOHEAD (1<<0)
  33 #define DEFAULT_OCTOPUS (1<<1)
  34 #define NO_FAST_FORWARD (1<<2)
  35 #define NO_TRIVIAL      (1<<3)
  36
  37 struct strategy {
  38         const char *name;
  39         unsigned attr;
  40 };
  41
  42 static const char * const builtin_merge_usage[] = {
  43         "git merge [options] [<commit>...]",
  44         "git merge [options] <msg> HEAD <commit>",
  45         "git merge --abort",
  46         NULL
  47 };
  48
  49 static int show_diffstat = 1, shortlog_len = -1, squash;
  50 static int option_commit = 1, allow_fast_forward = 1;
  51 static int fast_forward_only, option_edit;
  52 static int allow_trivial = 1, have_message;
  53 static int overwrite_ignore = 1;
  54 static struct strbuf merge_msg = STRBUF_INIT;
  55 static struct commit_list *remoteheads;
  56 static struct strategy **use_strategies;
  57 static size_t use_strategies_nr, use_strategies_alloc;
  58 static const char **xopts;
  59 static size_t xopts_nr, xopts_alloc;
  60 static const char *branch;
  61 static char *branch_mergeoptions;
  62 static int option_renormalize;
  63 static int verbosity;
  64 static int allow_rerere_auto;
  65 static int abort_current_merge;
  66 static int show_progress = -1;
  67 static int default_to_upstream;
  68 static const char *sign_commit;
  69
  70 static struct strategy all_strategy[] = {
  71         { "recursive",  DEFAULT_TWOHEAD | NO_TRIVIAL },
  72         { "octopus",    DEFAULT_OCTOPUS },
  73         { "resolve",    0 },
  74         { "ours",       NO_FAST_FORWARD | NO_TRIVIAL },
  75         { "subtree",    NO_FAST_FORWARD | NO_TRIVIAL },
  76 };
  77
  78 static const char *pull_twohead, *pull_octopus;
  79
  80 static int option_parse_message(const struct option *opt,
  81                                 const char *arg, int unset)
  82 {
  83         struct strbuf *buf = opt->value;
  84
  85         if (unset)
  86                 strbuf_setlen(buf, 0);
  87         else if (arg) {
  88                 strbuf_addf(buf, "%s%s", buf->len ? "\n\n" : "", arg);
  89                 have_message = 1;
  90         } else
  91                 return error(_("switch `m' requires a value"));
  92         return 0;
  93 }
  94
  95 static struct strategy *get_strategy(const char *name)
  96 {
  97         int i;
  98         struct strategy *ret;
  99         static struct cmdnames main_cmds, other_cmds;
 100         static int loaded;
 101
 102         if (!name)
 103                 return NULL;
 104
 105         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 106                 if (!strcmp(name, all_strategy[i].name))
 107                         return &all_strategy[i];
 108
 109         if (!loaded) {
 110                 struct cmdnames not_strategies;
 111                 loaded = 1;
 112
 113                 memset(&not_strategies, 0, sizeof(struct cmdnames));
 114                 load_command_list("git-merge-", &main_cmds, &other_cmds);
 115                 for (i = 0; i < main_cmds.cnt; i++) {
 116                         int j, found = 0;
 117                         struct cmdname *ent = main_cmds.names[i];
 118                         for (j = 0; j < ARRAY_SIZE(all_strategy); j++)
 119                                 if (!strncmp(ent->name, all_strategy[j].name, ent->len)
 120                                                 && !all_strategy[j].name[ent->len])
 121                                         found = 1;
 122                         if (!found)
 123                                 add_cmdname(&not_strategies, ent->name, ent->len);
 124                 }
 125                 exclude_cmds(&main_cmds, &not_strategies);
 126         }
 127         if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
 128                 fprintf(stderr, _("Could not find merge strategy '%s'.\n"), name);
 129                 fprintf(stderr, _("Available strategies are:"));
 130                 for (i = 0; i < main_cmds.cnt; i++)
 131                         fprintf(stderr, " %s", main_cmds.names[i]->name);
 132                 fprintf(stderr, ".\n");
 133                 if (other_cmds.cnt) {
 134                         fprintf(stderr, _("Available custom strategies are:"));
 135                         for (i = 0; i < other_cmds.cnt; i++)
 136                                 fprintf(stderr, " %s", other_cmds.names[i]->name);
 137                         fprintf(stderr, ".\n");
 138                 }
 139                 exit(1);
 140         }
 141
 142         ret = xcalloc(1, sizeof(struct strategy));
 143         ret->name = xstrdup(name);
 144         ret->attr = NO_TRIVIAL;
 145         return ret;
 146 }
 147
 148 static void append_strategy(struct strategy *s)
 149 {
 150         ALLOC_GROW(use_strategies, use_strategies_nr + 1, use_strategies_alloc);
 151         use_strategies[use_strategies_nr++] = s;
 152 }
 153
 154 static int option_parse_strategy(const struct option *opt,
 155                                  const char *name, int unset)
 156 {
 157         if (unset)
 158                 return 0;
 159
 160         append_strategy(get_strategy(name));
 161         return 0;
 162 }
 163
 164 static int option_parse_x(const struct option *opt,
 165                           const char *arg, int unset)
 166 {
 167         if (unset)
 168                 return 0;
 169
 170         ALLOC_GROW(xopts, xopts_nr + 1, xopts_alloc);
 171         xopts[xopts_nr++] = xstrdup(arg);
 172         return 0;
 173 }
 174
 175 static int option_parse_n(const struct option *opt,
 176                           const char *arg, int unset)
 177 {
 178         show_diffstat = unset;
 179         return 0;
 180 }
 181
 182 static struct option builtin_merge_options[] = {
 183         { OPTION_CALLBACK, 'n', NULL, NULL, NULL,
 184                 "do not show a diffstat at the end of the merge",
 185                 PARSE_OPT_NOARG, option_parse_n },
 186         OPT_BOOLEAN(0, "stat", &show_diffstat,
 187                 "show a diffstat at the end of the merge"),
 188         OPT_BOOLEAN(0, "summary", &show_diffstat, "(synonym to --stat)"),
 189         { OPTION_INTEGER, 0, "log", &shortlog_len, "n",
 190           "add (at most <n>) entries from shortlog to merge commit message",
 191           PARSE_OPT_OPTARG, NULL, DEFAULT_MERGE_LOG_LEN },
 192         OPT_BOOLEAN(0, "squash", &squash,
 193                 "create a single commit instead of doing a merge"),
 194         OPT_BOOLEAN(0, "commit", &option_commit,
 195                 "perform a commit if the merge succeeds (default)"),
 196         OPT_BOOLEAN('e', "edit", &option_edit,
 197                 "edit message before committing"),
 198         OPT_BOOLEAN(0, "ff", &allow_fast_forward,
 199                 "allow fast-forward (default)"),
 200         OPT_BOOLEAN(0, "ff-only", &fast_forward_only,
 201                 "abort if fast-forward is not possible"),
 202         OPT_RERERE_AUTOUPDATE(&allow_rerere_auto),
 203         OPT_CALLBACK('s', "strategy", &use_strategies, "strategy",
 204                 "merge strategy to use", option_parse_strategy),
 205         OPT_CALLBACK('X', "strategy-option", &xopts, "option=value",
 206                 "option for selected merge strategy", option_parse_x),
 207         OPT_CALLBACK('m', "message", &merge_msg, "message",
 208                 "merge commit message (for a non-fast-forward merge)",
 209                 option_parse_message),
 210         OPT__VERBOSITY(&verbosity),
 211         OPT_BOOLEAN(0, "abort", &abort_current_merge,
 212                 "abort the current in-progress merge"),
 213         OPT_SET_INT(0, "progress", &show_progress, "force progress reporting", 1),
 214         { OPTION_STRING, 'S', "gpg-sign", &sign_commit, "key id",
 215           "GPG sign commit", PARSE_OPT_OPTARG, NULL, (intptr_t) "" },
 216         OPT_BOOLEAN(0, "overwrite-ignore", &overwrite_ignore, "update ignored files (default)"),
 217         OPT_END()
 218 };
 219
 220 /* Cleans up metadata that is uninteresting after a succeeded merge. */
 221 static void drop_save(void)
 222 {
 223         unlink(git_path("MERGE_HEAD"));
 224         unlink(git_path("MERGE_MSG"));
 225         unlink(git_path("MERGE_MODE"));
 226 }
 227
 228 static int save_state(unsigned char *stash)
 229 {
 230         int len;
 231         struct child_process cp;
 232         struct strbuf buffer = STRBUF_INIT;
 233         const char *argv[] = {"stash", "create", NULL};
 234
 235         memset(&cp, 0, sizeof(cp));
 236         cp.argv = argv;
 237         cp.out = -1;
 238         cp.git_cmd = 1;
 239
 240         if (start_command(&cp))
 241                 die(_("could not run stash."));
 242         len = strbuf_read(&buffer, cp.out, 1024);
 243         close(cp.out);
 244
 245         if (finish_command(&cp) || len < 0)
 246                 die(_("stash failed"));
 247         else if (!len)          /* no changes */
 248                 return -1;
 249         strbuf_setlen(&buffer, buffer.len-1);
 250         if (get_sha1(buffer.buf, stash))
 251                 die(_("not a valid object: %s"), buffer.buf);
 252         return 0;
 253 }
 254
 255 static void read_empty(unsigned const char *sha1, int verbose)
 256 {
 257         int i = 0;
 258         const char *args[7];
 259
 260         args[i++] = "read-tree";
 261         if (verbose)
 262                 args[i++] = "-v";
 263         args[i++] = "-m";
 264         args[i++] = "-u";
 265         args[i++] = EMPTY_TREE_SHA1_HEX;
 266         args[i++] = sha1_to_hex(sha1);
 267         args[i] = NULL;
 268
 269         if (run_command_v_opt(args, RUN_GIT_CMD))
 270                 die(_("read-tree failed"));
 271 }
 272
 273 static void reset_hard(unsigned const char *sha1, int verbose)
 274 {
 275         int i = 0;
 276         const char *args[6];
 277
 278         args[i++] = "read-tree";
 279         if (verbose)
 280                 args[i++] = "-v";
 281         args[i++] = "--reset";
 282         args[i++] = "-u";
 283         args[i++] = sha1_to_hex(sha1);
 284         args[i] = NULL;
 285
 286         if (run_command_v_opt(args, RUN_GIT_CMD))
 287                 die(_("read-tree failed"));
 288 }
 289
 290 static void restore_state(const unsigned char *head,
 291                           const unsigned char *stash)
 292 {
 293         struct strbuf sb = STRBUF_INIT;
 294         const char *args[] = { "stash", "apply", NULL, NULL };
 295
 296         if (is_null_sha1(stash))
 297                 return;
 298
 299         reset_hard(head, 1);
 300
 301         args[2] = sha1_to_hex(stash);
 302
 303         /*
 304          * It is OK to ignore error here, for example when there was
 305          * nothing to restore.
 306          */
 307         run_command_v_opt(args, RUN_GIT_CMD);
 308
 309         strbuf_release(&sb);
 310         refresh_cache(REFRESH_QUIET);
 311 }
 312
 313 /* This is called when no merge was necessary. */
 314 static void finish_up_to_date(const char *msg)
 315 {
 316         if (verbosity >= 0)
 317                 printf("%s%s\n", squash ? _(" (nothing to squash)") : "", msg);
 318         drop_save();
 319 }
 320
 321 static void squash_message(struct commit *commit)
 322 {
 323         struct rev_info rev;
 324         struct strbuf out = STRBUF_INIT;
 325         struct commit_list *j;
 326         const char *filename;
 327         int fd;
 328         struct pretty_print_context ctx = {0};
 329
 330         printf(_("Squash commit -- not updating HEAD\n"));
 331         filename = git_path("SQUASH_MSG");
 332         fd = open(filename, O_WRONLY | O_CREAT, 0666);
 333         if (fd < 0)
 334                 die_errno(_("Could not write to '%s'"), filename);
 335
 336         init_revisions(&rev, NULL);
 337         rev.ignore_merges = 1;
 338         rev.commit_format = CMIT_FMT_MEDIUM;
 339
 340         commit->object.flags |= UNINTERESTING;
 341         add_pending_object(&rev, &commit->object, NULL);
 342
 343         for (j = remoteheads; j; j = j->next)
 344                 add_pending_object(&rev, &j->item->object, NULL);
 345
 346         setup_revisions(0, NULL, &rev, NULL);
 347         if (prepare_revision_walk(&rev))
 348                 die(_("revision walk setup failed"));
 349
 350         ctx.abbrev = rev.abbrev;
 351         ctx.date_mode = rev.date_mode;
 352         ctx.fmt = rev.commit_format;
 353
 354         strbuf_addstr(&out, "Squashed commit of the following:\n");
 355         while ((commit = get_revision(&rev)) != NULL) {
 356                 strbuf_addch(&out, '\n');
 357                 strbuf_addf(&out, "commit %s\n",
 358                         sha1_to_hex(commit->object.sha1));
 359                 pretty_print_commit(&ctx, commit, &out);
 360         }
 361         if (write(fd, out.buf, out.len) < 0)
 362                 die_errno(_("Writing SQUASH_MSG"));
 363         if (close(fd))
 364                 die_errno(_("Finishing SQUASH_MSG"));
 365         strbuf_release(&out);
 366 }
 367
 368 static void finish(struct commit *head_commit,
 369                    const unsigned char *new_head, const char *msg)
 370 {
 371         struct strbuf reflog_message = STRBUF_INIT;
 372         const unsigned char *head = head_commit->object.sha1;
 373
 374         if (!msg)
 375                 strbuf_addstr(&reflog_message, getenv("GIT_REFLOG_ACTION"));
 376         else {
 377                 if (verbosity >= 0)
 378                         printf("%s\n", msg);
 379                 strbuf_addf(&reflog_message, "%s: %s",
 380                         getenv("GIT_REFLOG_ACTION"), msg);
 381         }
 382         if (squash) {
 383                 squash_message(head_commit);
 384         } else {
 385                 if (verbosity >= 0 && !merge_msg.len)
 386                         printf(_("No merge message -- not updating HEAD\n"));
 387                 else {
 388                         const char *argv_gc_auto[] = { "gc", "--auto", NULL };
 389                         update_ref(reflog_message.buf, "HEAD",
 390                                 new_head, head, 0,
 391                                 DIE_ON_ERR);
 392                         /*
 393                          * We ignore errors in 'gc --auto', since the
 394                          * user should see them.
 395                          */
 396                         run_command_v_opt(argv_gc_auto, RUN_GIT_CMD);
 397                 }
 398         }
 399         if (new_head && show_diffstat) {
 400                 struct diff_options opts;
 401                 diff_setup(&opts);
 402                 opts.stat_width = -1; /* use full terminal width */
 403                 opts.output_format |=
 404                         DIFF_FORMAT_SUMMARY | DIFF_FORMAT_DIFFSTAT;
 405                 opts.detect_rename = DIFF_DETECT_RENAME;
 406                 if (diff_setup_done(&opts) < 0)
 407                         die(_("diff_setup_done failed"));
 408                 diff_tree_sha1(head, new_head, "", &opts);
 409                 diffcore_std(&opts);
 410                 diff_flush(&opts);
 411         }
 412
 413         /* Run a post-merge hook */
 414         run_hook(NULL, "post-merge", squash ? "1" : "0", NULL);
 415
 416         strbuf_release(&reflog_message);
 417 }
 418
 419 /* Get the name for the merge commit's message. */
 420 static void merge_name(const char *remote, struct strbuf *msg)
 421 {
 422         struct commit *remote_head;
 423         unsigned char branch_head[20];
 424         struct strbuf buf = STRBUF_INIT;
 425         struct strbuf bname = STRBUF_INIT;
 426         const char *ptr;
 427         char *found_ref;
 428         int len, early;
 429
 430         strbuf_branchname(&bname, remote);
 431         remote = bname.buf;
 432
 433         memset(branch_head, 0, sizeof(branch_head));
 434         remote_head = get_merge_parent(remote);
 435         if (!remote_head)
 436                 die(_("'%s' does not point to a commit"), remote);
 437
 438         if (dwim_ref(remote, strlen(remote), branch_head, &found_ref) > 0) {
 439                 if (!prefixcmp(found_ref, "refs/heads/")) {
 440                         strbuf_addf(msg, "%s\t\tbranch '%s' of .\n",
 441                                     sha1_to_hex(branch_head), remote);
 442                         goto cleanup;
 443                 }
 444                 if (!prefixcmp(found_ref, "refs/tags/")) {
 445                         strbuf_addf(msg, "%s\t\ttag '%s' of .\n",
 446                                     sha1_to_hex(branch_head), remote);
 447                         goto cleanup;
 448                 }
 449                 if (!prefixcmp(found_ref, "refs/remotes/")) {
 450                         strbuf_addf(msg, "%s\t\tremote-tracking branch '%s' of .\n",
 451                                     sha1_to_hex(branch_head), remote);
 452                         goto cleanup;
 453                 }
 454         }
 455
 456         /* See if remote matches <name>^^^.. or <name>~<number> */
 457         for (len = 0, ptr = remote + strlen(remote);
 458              remote < ptr && ptr[-1] == '^';
 459              ptr--)
 460                 len++;
 461         if (len)
 462                 early = 1;
 463         else {
 464                 early = 0;
 465                 ptr = strrchr(remote, '~');
 466                 if (ptr) {
 467                         int seen_nonzero = 0;
 468
 469                         len++; /* count ~ */
 470                         while (*++ptr && isdigit(*ptr)) {
 471                                 seen_nonzero |= (*ptr != '0');
 472                                 len++;
 473                         }
 474                         if (*ptr)
 475                                 len = 0; /* not ...~<number> */
 476                         else if (seen_nonzero)
 477                                 early = 1;
 478                         else if (len == 1)
 479                                 early = 1; /* "name~" is "name~1"! */
 480                 }
 481         }
 482         if (len) {
 483                 struct strbuf truname = STRBUF_INIT;
 484                 strbuf_addstr(&truname, "refs/heads/");
 485                 strbuf_addstr(&truname, remote);
 486                 strbuf_setlen(&truname, truname.len - len);
 487                 if (ref_exists(truname.buf)) {
 488                         strbuf_addf(msg,
 489                                     "%s\t\tbranch '%s'%s of .\n",
 490                                     sha1_to_hex(remote_head->object.sha1),
 491                                     truname.buf + 11,
 492                                     (early ? " (early part)" : ""));
 493                         strbuf_release(&truname);
 494                         goto cleanup;
 495                 }
 496         }
 497
 498         if (!strcmp(remote, "FETCH_HEAD") &&
 499                         !access(git_path("FETCH_HEAD"), R_OK)) {
 500                 const char *filename;
 501                 FILE *fp;
 502                 struct strbuf line = STRBUF_INIT;
 503                 char *ptr;
 504
 505                 filename = git_path("FETCH_HEAD");
 506                 fp = fopen(filename, "r");
 507                 if (!fp)
 508                         die_errno(_("could not open '%s' for reading"),
 509                                   filename);
 510                 strbuf_getline(&line, fp, '\n');
 511                 fclose(fp);
 512                 ptr = strstr(line.buf, "\tnot-for-merge\t");
 513                 if (ptr)
 514                         strbuf_remove(&line, ptr-line.buf+1, 13);
 515                 strbuf_addbuf(msg, &line);
 516                 strbuf_release(&line);
 517                 goto cleanup;
 518         }
 519         strbuf_addf(msg, "%s\t\tcommit '%s'\n",
 520                 sha1_to_hex(remote_head->object.sha1), remote);
 521 cleanup:
 522         strbuf_release(&buf);
 523         strbuf_release(&bname);
 524 }
 525
 526 static void parse_branch_merge_options(char *bmo)
 527 {
 528         const char **argv;
 529         int argc;
 530
 531         if (!bmo)
 532                 return;
 533         argc = split_cmdline(bmo, &argv);
 534         if (argc < 0)
 535                 die(_("Bad branch.%s.mergeoptions string: %s"), branch,
 536                     split_cmdline_strerror(argc));
 537         argv = xrealloc(argv, sizeof(*argv) * (argc + 2));
 538         memmove(argv + 1, argv, sizeof(*argv) * (argc + 1));
 539         argc++;
 540         argv[0] = "branch.*.mergeoptions";
 541         parse_options(argc, argv, NULL, builtin_merge_options,
 542                       builtin_merge_usage, 0);
 543         free(argv);
 544 }
 545
 546 static int git_merge_config(const char *k, const char *v, void *cb)
 547 {
 548         int status;
 549
 550         if (branch && !prefixcmp(k, "branch.") &&
 551                 !prefixcmp(k + 7, branch) &&
 552                 !strcmp(k + 7 + strlen(branch), ".mergeoptions")) {
 553                 free(branch_mergeoptions);
 554                 branch_mergeoptions = xstrdup(v);
 555                 return 0;
 556         }
 557
 558         if (!strcmp(k, "merge.diffstat") || !strcmp(k, "merge.stat"))
 559                 show_diffstat = git_config_bool(k, v);
 560         else if (!strcmp(k, "pull.twohead"))
 561                 return git_config_string(&pull_twohead, k, v);
 562         else if (!strcmp(k, "pull.octopus"))
 563                 return git_config_string(&pull_octopus, k, v);
 564         else if (!strcmp(k, "merge.renormalize"))
 565                 option_renormalize = git_config_bool(k, v);
 566         else if (!strcmp(k, "merge.ff")) {
 567                 int boolval = git_config_maybe_bool(k, v);
 568                 if (0 <= boolval) {
 569                         allow_fast_forward = boolval;
 570                 } else if (v && !strcmp(v, "only")) {
 571                         allow_fast_forward = 1;
 572                         fast_forward_only = 1;
 573                 } /* do not barf on values from future versions of git */
 574                 return 0;
 575         } else if (!strcmp(k, "merge.defaulttoupstream")) {
 576                 default_to_upstream = git_config_bool(k, v);
 577                 return 0;
 578         }
 579
 580         status = fmt_merge_msg_config(k, v, cb);
 581         if (status)
 582                 return status;
 583         status = git_gpg_config(k, v, NULL);
 584         if (status)
 585                 return status;
 586         return git_diff_ui_config(k, v, cb);
 587 }
 588
 589 static int read_tree_trivial(unsigned char *common, unsigned char *head,
 590                              unsigned char *one)
 591 {
 592         int i, nr_trees = 0;
 593         struct tree *trees[MAX_UNPACK_TREES];
 594         struct tree_desc t[MAX_UNPACK_TREES];
 595         struct unpack_trees_options opts;
 596
 597         memset(&opts, 0, sizeof(opts));
 598         opts.head_idx = 2;
 599         opts.src_index = &the_index;
 600         opts.dst_index = &the_index;
 601         opts.update = 1;
 602         opts.verbose_update = 1;
 603         opts.trivial_merges_only = 1;
 604         opts.merge = 1;
 605         trees[nr_trees] = parse_tree_indirect(common);
 606         if (!trees[nr_trees++])
 607                 return -1;
 608         trees[nr_trees] = parse_tree_indirect(head);
 609         if (!trees[nr_trees++])
 610                 return -1;
 611         trees[nr_trees] = parse_tree_indirect(one);
 612         if (!trees[nr_trees++])
 613                 return -1;
 614         opts.fn = threeway_merge;
 615         cache_tree_free(&active_cache_tree);
 616         for (i = 0; i < nr_trees; i++) {
 617                 parse_tree(trees[i]);
 618                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 619         }
 620         if (unpack_trees(nr_trees, t, &opts))
 621                 return -1;
 622         return 0;
 623 }
 624
 625 static void write_tree_trivial(unsigned char *sha1)
 626 {
 627         if (write_cache_as_tree(sha1, 0, NULL))
 628                 die(_("git write-tree failed to write a tree"));
 629 }
 630
 631 static const char *merge_argument(struct commit *commit)
 632 {
 633         if (commit)
 634                 return sha1_to_hex(commit->object.sha1);
 635         else
 636                 return EMPTY_TREE_SHA1_HEX;
 637 }
 638
 639 int try_merge_command(const char *strategy, size_t xopts_nr,
 640                       const char **xopts, struct commit_list *common,
 641                       const char *head_arg, struct commit_list *remotes)
 642 {
 643         const char **args;
 644         int i = 0, x = 0, ret;
 645         struct commit_list *j;
 646         struct strbuf buf = STRBUF_INIT;
 647
 648         args = xmalloc((4 + xopts_nr + commit_list_count(common) +
 649                         commit_list_count(remotes)) * sizeof(char *));
 650         strbuf_addf(&buf, "merge-%s", strategy);
 651         args[i++] = buf.buf;
 652         for (x = 0; x < xopts_nr; x++) {
 653                 char *s = xmalloc(strlen(xopts[x])+2+1);
 654                 strcpy(s, "--");
 655                 strcpy(s+2, xopts[x]);
 656                 args[i++] = s;
 657         }
 658         for (j = common; j; j = j->next)
 659                 args[i++] = xstrdup(merge_argument(j->item));
 660         args[i++] = "--";
 661         args[i++] = head_arg;
 662         for (j = remotes; j; j = j->next)
 663                 args[i++] = xstrdup(merge_argument(j->item));
 664         args[i] = NULL;
 665         ret = run_command_v_opt(args, RUN_GIT_CMD);
 666         strbuf_release(&buf);
 667         i = 1;
 668         for (x = 0; x < xopts_nr; x++)
 669                 free((void *)args[i++]);
 670         for (j = common; j; j = j->next)
 671                 free((void *)args[i++]);
 672         i += 2;
 673         for (j = remotes; j; j = j->next)
 674                 free((void *)args[i++]);
 675         free(args);
 676         discard_cache();
 677         if (read_cache() < 0)
 678                 die(_("failed to read the cache"));
 679         resolve_undo_clear();
 680
 681         return ret;
 682 }
 683
 684 static int try_merge_strategy(const char *strategy, struct commit_list *common,
 685                               struct commit *head, const char *head_arg)
 686 {
 687         int index_fd;
 688         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 689
 690         index_fd = hold_locked_index(lock, 1);
 691         refresh_cache(REFRESH_QUIET);
 692         if (active_cache_changed &&
 693                         (write_cache(index_fd, active_cache, active_nr) ||
 694                          commit_locked_index(lock)))
 695                 return error(_("Unable to write index."));
 696         rollback_lock_file(lock);
 697
 698         if (!strcmp(strategy, "recursive") || !strcmp(strategy, "subtree")) {
 699                 int clean, x;
 700                 struct commit *result;
 701                 struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
 702                 int index_fd;
 703                 struct commit_list *reversed = NULL;
 704                 struct merge_options o;
 705                 struct commit_list *j;
 706
 707                 if (remoteheads->next) {
 708                         error(_("Not handling anything other than two heads merge."));
 709                         return 2;
 710                 }
 711
 712                 init_merge_options(&o);
 713                 if (!strcmp(strategy, "subtree"))
 714                         o.subtree_shift = "";
 715
 716                 o.renormalize = option_renormalize;
 717                 o.show_rename_progress =
 718                         show_progress == -1 ? isatty(2) : show_progress;
 719
 720                 for (x = 0; x < xopts_nr; x++)
 721                         if (parse_merge_opt(&o, xopts[x]))
 722                                 die(_("Unknown option for merge-recursive: -X%s"), xopts[x]);
 723
 724                 o.branch1 = head_arg;
 725                 o.branch2 = merge_remote_util(remoteheads->item)->name;
 726
 727                 for (j = common; j; j = j->next)
 728                         commit_list_insert(j->item, &reversed);
 729
 730                 index_fd = hold_locked_index(lock, 1);
 731                 clean = merge_recursive(&o, head,
 732                                 remoteheads->item, reversed, &result);
 733                 if (active_cache_changed &&
 734                                 (write_cache(index_fd, active_cache, active_nr) ||
 735                                  commit_locked_index(lock)))
 736                         die (_("unable to write %s"), get_index_file());
 737                 rollback_lock_file(lock);
 738                 return clean ? 0 : 1;
 739         } else {
 740                 return try_merge_command(strategy, xopts_nr, xopts,
 741                                                 common, head_arg, remoteheads);
 742         }
 743 }
 744
 745 static void count_diff_files(struct diff_queue_struct *q,
 746                              struct diff_options *opt, void *data)
 747 {
 748         int *count = data;
 749
 750         (*count) += q->nr;
 751 }
 752
 753 static int count_unmerged_entries(void)
 754 {
 755         int i, ret = 0;
 756
 757         for (i = 0; i < active_nr; i++)
 758                 if (ce_stage(active_cache[i]))
 759                         ret++;
 760
 761         return ret;
 762 }
 763
 764 int checkout_fast_forward(const unsigned char *head, const unsigned char *remote)
 765 {
 766         struct tree *trees[MAX_UNPACK_TREES];
 767         struct unpack_trees_options opts;
 768         struct tree_desc t[MAX_UNPACK_TREES];
 769         int i, fd, nr_trees = 0;
 770         struct dir_struct dir;
 771         struct lock_file *lock_file = xcalloc(1, sizeof(struct lock_file));
 772
 773         refresh_cache(REFRESH_QUIET);
 774
 775         fd = hold_locked_index(lock_file, 1);
 776
 777         memset(&trees, 0, sizeof(trees));
 778         memset(&opts, 0, sizeof(opts));
 779         memset(&t, 0, sizeof(t));
 780         if (overwrite_ignore) {
 781                 memset(&dir, 0, sizeof(dir));
 782                 dir.flags |= DIR_SHOW_IGNORED;
 783                 setup_standard_excludes(&dir);
 784                 opts.dir = &dir;
 785         }
 786
 787         opts.head_idx = 1;
 788         opts.src_index = &the_index;
 789         opts.dst_index = &the_index;
 790         opts.update = 1;
 791         opts.verbose_update = 1;
 792         opts.merge = 1;
 793         opts.fn = twoway_merge;
 794         setup_unpack_trees_porcelain(&opts, "merge");
 795
 796         trees[nr_trees] = parse_tree_indirect(head);
 797         if (!trees[nr_trees++])
 798                 return -1;
 799         trees[nr_trees] = parse_tree_indirect(remote);
 800         if (!trees[nr_trees++])
 801                 return -1;
 802         for (i = 0; i < nr_trees; i++) {
 803                 parse_tree(trees[i]);
 804                 init_tree_desc(t+i, trees[i]->buffer, trees[i]->size);
 805         }
 806         if (unpack_trees(nr_trees, t, &opts))
 807                 return -1;
 808         if (write_cache(fd, active_cache, active_nr) ||
 809                 commit_locked_index(lock_file))
 810                 die(_("unable to write new index file"));
 811         return 0;
 812 }
 813
 814 static void split_merge_strategies(const char *string, struct strategy **list,
 815                                    int *nr, int *alloc)
 816 {
 817         char *p, *q, *buf;
 818
 819         if (!string)
 820                 return;
 821
 822         buf = xstrdup(string);
 823         q = buf;
 824         for (;;) {
 825                 p = strchr(q, ' ');
 826                 if (!p) {
 827                         ALLOC_GROW(*list, *nr + 1, *alloc);
 828                         (*list)[(*nr)++].name = xstrdup(q);
 829                         free(buf);
 830                         return;
 831                 } else {
 832                         *p = '\0';
 833                         ALLOC_GROW(*list, *nr + 1, *alloc);
 834                         (*list)[(*nr)++].name = xstrdup(q);
 835                         q = ++p;
 836                 }
 837         }
 838 }
 839
 840 static void add_strategies(const char *string, unsigned attr)
 841 {
 842         struct strategy *list = NULL;
 843         int list_alloc = 0, list_nr = 0, i;
 844
 845         memset(&list, 0, sizeof(list));
 846         split_merge_strategies(string, &list, &list_nr, &list_alloc);
 847         if (list) {
 848                 for (i = 0; i < list_nr; i++)
 849                         append_strategy(get_strategy(list[i].name));
 850                 return;
 851         }
 852         for (i = 0; i < ARRAY_SIZE(all_strategy); i++)
 853                 if (all_strategy[i].attr & attr)
 854                         append_strategy(&all_strategy[i]);
 855
 856 }
 857
 858 static void write_merge_msg(struct strbuf *msg)
 859 {
 860         const char *filename = git_path("MERGE_MSG");
 861         int fd = open(filename, O_WRONLY | O_CREAT, 0666);
 862         if (fd < 0)
 863                 die_errno(_("Could not open '%s' for writing"),
 864                           filename);
 865         if (write_in_full(fd, msg->buf, msg->len) != msg->len)
 866                 die_errno(_("Could not write to '%s'"), filename);
 867         close(fd);
 868 }
 869
 870 static void read_merge_msg(struct strbuf *msg)
 871 {
 872         const char *filename = git_path("MERGE_MSG");
 873         strbuf_reset(msg);
 874         if (strbuf_read_file(msg, filename, 0) < 0)
 875                 die_errno(_("Could not read from '%s'"), filename);
 876 }
 877
 878 static void write_merge_state(void);
 879 static void abort_commit(const char *err_msg)
 880 {
 881         if (err_msg)
 882                 error("%s", err_msg);
 883         fprintf(stderr,
 884                 _("Not committing merge; use 'git commit' to complete the merge.\n"));
 885         write_merge_state();
 886         exit(1);
 887 }
 888
 889 static void prepare_to_commit(void)
 890 {
 891         struct strbuf msg = STRBUF_INIT;
 892         strbuf_addbuf(&msg, &merge_msg);
 893         strbuf_addch(&msg, '\n');
 894         write_merge_msg(&msg);
 895         run_hook(get_index_file(), "prepare-commit-msg",
 896                  git_path("MERGE_MSG"), "merge", NULL, NULL);
 897         if (option_edit) {
 898                 if (launch_editor(git_path("MERGE_MSG"), NULL, NULL))
 899                         abort_commit(NULL);
 900         }
 901         read_merge_msg(&msg);
 902         stripspace(&msg, option_edit);
 903         if (!msg.len)
 904                 abort_commit(_("Empty commit message."));
 905         strbuf_release(&merge_msg);
 906         strbuf_addbuf(&merge_msg, &msg);
 907         strbuf_release(&msg);
 908 }
 909
 910 static int merge_trivial(struct commit *head)
 911 {
 912         unsigned char result_tree[20], result_commit[20];
 913         struct commit_list *parent = xmalloc(sizeof(*parent));
 914
 915         write_tree_trivial(result_tree);
 916         printf(_("Wonderful.\n"));
 917         parent->item = head;
 918         parent->next = xmalloc(sizeof(*parent->next));
 919         parent->next->item = remoteheads->item;
 920         parent->next->next = NULL;
 921         prepare_to_commit();
 922         if (commit_tree(&merge_msg, result_tree, parent, result_commit, NULL,
 923                         sign_commit))
 924                 die(_("failed to write commit object"));
 925         finish(head, result_commit, "In-index merge");
 926         drop_save();
 927         return 0;
 928 }
 929
 930 static int finish_automerge(struct commit *head,
 931                             struct commit_list *common,
 932                             unsigned char *result_tree,
 933                             const char *wt_strategy)
 934 {
 935         struct commit_list *parents = NULL, *j;
 936         struct strbuf buf = STRBUF_INIT;
 937         unsigned char result_commit[20];
 938
 939         free_commit_list(common);
 940         if (allow_fast_forward) {
 941                 parents = remoteheads;
 942                 commit_list_insert(head, &parents);
 943                 parents = reduce_heads(parents);
 944         } else {
 945                 struct commit_list **pptr = &parents;
 946
 947                 pptr = &commit_list_insert(head,
 948                                 pptr)->next;
 949                 for (j = remoteheads; j; j = j->next)
 950                         pptr = &commit_list_insert(j->item, pptr)->next;
 951         }
 952         strbuf_addch(&merge_msg, '\n');
 953         prepare_to_commit();
 954         free_commit_list(remoteheads);
 955         if (commit_tree(&merge_msg, result_tree, parents, result_commit,
 956                         NULL, sign_commit))
 957                 die(_("failed to write commit object"));
 958         strbuf_addf(&buf, "Merge made by the '%s' strategy.", wt_strategy);
 959         finish(head, result_commit, buf.buf);
 960         strbuf_release(&buf);
 961         drop_save();
 962         return 0;
 963 }
 964
 965 static int suggest_conflicts(int renormalizing)
 966 {
 967         const char *filename;
 968         FILE *fp;
 969         int pos;
 970
 971         filename = git_path("MERGE_MSG");
 972         fp = fopen(filename, "a");
 973         if (!fp)
 974                 die_errno(_("Could not open '%s' for writing"), filename);
 975         fprintf(fp, "\nConflicts:\n");
 976         for (pos = 0; pos < active_nr; pos++) {
 977                 struct cache_entry *ce = active_cache[pos];
 978
 979                 if (ce_stage(ce)) {
 980                         fprintf(fp, "\t%s\n", ce->name);
 981                         while (pos + 1 < active_nr &&
 982                                         !strcmp(ce->name,
 983                                                 active_cache[pos + 1]->name))
 984                                 pos++;
 985                 }
 986         }
 987         fclose(fp);
 988         rerere(allow_rerere_auto);
 989         printf(_("Automatic merge failed; "
 990                         "fix conflicts and then commit the result.\n"));
 991         return 1;
 992 }
 993
 994 static struct commit *is_old_style_invocation(int argc, const char **argv,
 995                                               const unsigned char *head)
 996 {
 997         struct commit *second_token = NULL;
 998         if (argc > 2) {
 999                 unsigned char second_sha1[20];
1000
1001                 if (get_sha1(argv[1], second_sha1))
1002                         return NULL;
1003                 second_token = lookup_commit_reference_gently(second_sha1, 0);
1004                 if (!second_token)
1005                         die(_("'%s' is not a commit"), argv[1]);
1006                 if (hashcmp(second_token->object.sha1, head))
1007                         return NULL;
1008         }
1009         return second_token;
1010 }
1011
1012 static int evaluate_result(void)
1013 {
1014         int cnt = 0;
1015         struct rev_info rev;
1016
1017         /* Check how many files differ. */
1018         init_revisions(&rev, "");
1019         setup_revisions(0, NULL, &rev, NULL);
1020         rev.diffopt.output_format |=
1021                 DIFF_FORMAT_CALLBACK;
1022         rev.diffopt.format_callback = count_diff_files;
1023         rev.diffopt.format_callback_data = &cnt;
1024         run_diff_files(&rev, 0);
1025
1026         /*
1027          * Check how many unmerged entries are
1028          * there.
1029          */
1030         cnt += count_unmerged_entries();
1031
1032         return cnt;
1033 }
1034
1035 /*
1036  * Pretend as if the user told us to merge with the tracking
1037  * branch we have for the upstream of the current branch
1038  */
1039 static int setup_with_upstream(const char ***argv)
1040 {
1041         struct branch *branch = branch_get(NULL);
1042         int i;
1043         const char **args;
1044
1045         if (!branch)
1046                 die(_("No current branch."));
1047         if (!branch->remote)
1048                 die(_("No remote for the current branch."));
1049         if (!branch->merge_nr)
1050                 die(_("No default upstream defined for the current branch."));
1051
1052         args = xcalloc(branch->merge_nr + 1, sizeof(char *));
1053         for (i = 0; i < branch->merge_nr; i++) {
1054                 if (!branch->merge[i]->dst)
1055                         die(_("No remote tracking branch for %s from %s"),
1056                             branch->merge[i]->src, branch->remote_name);
1057                 args[i] = branch->merge[i]->dst;
1058         }
1059         args[i] = NULL;
1060         *argv = args;
1061         return i;
1062 }
1063
1064 static void write_merge_state(void)
1065 {
1066         const char *filename;
1067         int fd;
1068         struct commit_list *j;
1069         struct strbuf buf = STRBUF_INIT;
1070
1071         for (j = remoteheads; j; j = j->next) {
1072                 unsigned const char *sha1;
1073                 struct commit *c = j->item;
1074                 if (c->util && merge_remote_util(c)->obj) {
1075                         sha1 = merge_remote_util(c)->obj->sha1;
1076                 } else {
1077                         sha1 = c->object.sha1;
1078                 }
1079                 strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
1080         }
1081         filename = git_path("MERGE_HEAD");
1082         fd = open(filename, O_WRONLY | O_CREAT, 0666);
1083         if (fd < 0)
1084                 die_errno(_("Could not open '%s' for writing"), filename);
1085         if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1086                 die_errno(_("Could not write to '%s'"), filename);
1087         close(fd);
1088         strbuf_addch(&merge_msg, '\n');
1089         write_merge_msg(&merge_msg);
1090
1091         filename = git_path("MERGE_MODE");
1092         fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0666);
1093         if (fd < 0)
1094                 die_errno(_("Could not open '%s' for writing"), filename);
1095         strbuf_reset(&buf);
1096         if (!allow_fast_forward)
1097                 strbuf_addf(&buf, "no-ff");
1098         if (write_in_full(fd, buf.buf, buf.len) != buf.len)
1099                 die_errno(_("Could not write to '%s'"), filename);
1100         close(fd);
1101 }
1102
1103 int cmd_merge(int argc, const char **argv, const char *prefix)
1104 {
1105         unsigned char result_tree[20];
1106         unsigned char stash[20];
1107         unsigned char head_sha1[20];
1108         struct commit *head_commit;
1109         struct strbuf buf = STRBUF_INIT;
1110         const char *head_arg;
1111         int flag, i, ret = 0;
1112         int best_cnt = -1, merge_was_ok = 0, automerge_was_ok = 0;
1113         struct commit_list *common = NULL;
1114         const char *best_strategy = NULL, *wt_strategy = NULL;
1115         struct commit_list **remotes = &remoteheads;
1116         void *branch_to_free;
1117
1118         if (argc == 2 && !strcmp(argv[1], "-h"))
1119                 usage_with_options(builtin_merge_usage, builtin_merge_options);
1120
1121         /*
1122          * Check if we are _not_ on a detached HEAD, i.e. if there is a
1123          * current branch.
1124          */
1125         branch = branch_to_free = resolve_refdup("HEAD", head_sha1, 0, &flag);
1126         if (branch && !prefixcmp(branch, "refs/heads/"))
1127                 branch += 11;
1128         if (!branch || is_null_sha1(head_sha1))
1129                 head_commit = NULL;
1130         else
1131                 head_commit = lookup_commit_or_die(head_sha1, "HEAD");
1132
1133         git_config(git_merge_config, NULL);
1134
1135         if (branch_mergeoptions)
1136                 parse_branch_merge_options(branch_mergeoptions);
1137         argc = parse_options(argc, argv, prefix, builtin_merge_options,
1138                         builtin_merge_usage, 0);
1139         if (shortlog_len < 0)
1140                 shortlog_len = (merge_log_config > 0) ? merge_log_config : 0;
1141
1142         if (verbosity < 0 && show_progress == -1)
1143                 show_progress = 0;
1144
1145         if (abort_current_merge) {
1146                 int nargc = 2;
1147                 const char *nargv[] = {"reset", "--merge", NULL};
1148
1149                 if (!file_exists(git_path("MERGE_HEAD")))
1150                         die(_("There is no merge to abort (MERGE_HEAD missing)."));
1151
1152                 /* Invoke 'git reset --merge' */
1153                 ret = cmd_reset(nargc, nargv, prefix);
1154                 goto done;
1155         }
1156
1157         if (read_cache_unmerged())
1158                 die_resolve_conflict("merge");
1159
1160         if (file_exists(git_path("MERGE_HEAD"))) {
1161                 /*
1162                  * There is no unmerged entry, don't advise 'git
1163                  * add/rm <file>', just 'git commit'.
1164                  */
1165                 if (advice_resolve_conflict)
1166                         die(_("You have not concluded your merge (MERGE_HEAD exists).\n"
1167                                   "Please, commit your changes before you can merge."));
1168                 else
1169                         die(_("You have not concluded your merge (MERGE_HEAD exists)."));
1170         }
1171         if (file_exists(git_path("CHERRY_PICK_HEAD"))) {
1172                 if (advice_resolve_conflict)
1173                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists).\n"
1174                             "Please, commit your changes before you can merge."));
1175                 else
1176                         die(_("You have not concluded your cherry-pick (CHERRY_PICK_HEAD exists)."));
1177         }
1178         resolve_undo_clear();
1179
1180         if (verbosity < 0)
1181                 show_diffstat = 0;
1182
1183         if (squash) {
1184                 if (!allow_fast_forward)
1185                         die(_("You cannot combine --squash with --no-ff."));
1186                 option_commit = 0;
1187         }
1188
1189         if (!allow_fast_forward && fast_forward_only)
1190                 die(_("You cannot combine --no-ff with --ff-only."));
1191
1192         if (!abort_current_merge) {
1193                 if (!argc) {
1194                         if (default_to_upstream)
1195                                 argc = setup_with_upstream(&argv);
1196                         else
1197                                 die(_("No commit specified and merge.defaultToUpstream not set."));
1198                 } else if (argc == 1 && !strcmp(argv[0], "-"))
1199                         argv[0] = "@{-1}";
1200         }
1201         if (!argc)
1202                 usage_with_options(builtin_merge_usage,
1203                         builtin_merge_options);
1204
1205         /*
1206          * This could be traditional "merge <msg> HEAD <commit>..."  and
1207          * the way we can tell it is to see if the second token is HEAD,
1208          * but some people might have misused the interface and used a
1209          * committish that is the same as HEAD there instead.
1210          * Traditional format never would have "-m" so it is an
1211          * additional safety measure to check for it.
1212          */
1213
1214         if (!have_message && head_commit &&
1215             is_old_style_invocation(argc, argv, head_commit->object.sha1)) {
1216                 strbuf_addstr(&merge_msg, argv[0]);
1217                 head_arg = argv[1];
1218                 argv += 2;
1219                 argc -= 2;
1220         } else if (!head_commit) {
1221                 struct commit *remote_head;
1222                 /*
1223                  * If the merged head is a valid one there is no reason
1224                  * to forbid "git merge" into a branch yet to be born.
1225                  * We do the same for "git pull".
1226                  */
1227                 if (argc != 1)
1228                         die(_("Can merge only exactly one commit into "
1229                                 "empty head"));
1230                 if (squash)
1231                         die(_("Squash commit into empty head not supported yet"));
1232                 if (!allow_fast_forward)
1233                         die(_("Non-fast-forward commit does not make sense into "
1234                             "an empty head"));
1235                 remote_head = get_merge_parent(argv[0]);
1236                 if (!remote_head)
1237                         die(_("%s - not something we can merge"), argv[0]);
1238                 read_empty(remote_head->object.sha1, 0);
1239                 update_ref("initial pull", "HEAD", remote_head->object.sha1,
1240                            NULL, 0, DIE_ON_ERR);
1241                 goto done;
1242         } else {
1243                 struct strbuf merge_names = STRBUF_INIT;
1244
1245                 /* We are invoked directly as the first-class UI. */
1246                 head_arg = "HEAD";
1247
1248                 /*
1249                  * All the rest are the commits being merged; prepare
1250                  * the standard merge summary message to be appended
1251                  * to the given message.
1252                  */
1253                 for (i = 0; i < argc; i++)
1254                         merge_name(argv[i], &merge_names);
1255
1256                 if (!have_message || shortlog_len) {
1257                         struct fmt_merge_msg_opts opts;
1258                         memset(&opts, 0, sizeof(opts));
1259                         opts.add_title = !have_message;
1260                         opts.shortlog_len = shortlog_len;
1261
1262                         fmt_merge_msg(&merge_names, &merge_msg, &opts);
1263                         if (merge_msg.len)
1264                                 strbuf_setlen(&merge_msg, merge_msg.len - 1);
1265                 }
1266         }
1267
1268         if (!head_commit || !argc)
1269                 usage_with_options(builtin_merge_usage,
1270                         builtin_merge_options);
1271
1272         strbuf_addstr(&buf, "merge");
1273         for (i = 0; i < argc; i++)
1274                 strbuf_addf(&buf, " %s", argv[i]);
1275         setenv("GIT_REFLOG_ACTION", buf.buf, 0);
1276         strbuf_reset(&buf);
1277
1278         for (i = 0; i < argc; i++) {
1279                 struct commit *commit = get_merge_parent(argv[i]);
1280                 if (!commit)
1281                         die(_("%s - not something we can merge"), argv[i]);
1282                 remotes = &commit_list_insert(commit, remotes)->next;
1283                 strbuf_addf(&buf, "GITHEAD_%s",
1284                             sha1_to_hex(commit->object.sha1));
1285                 setenv(buf.buf, argv[i], 1);
1286                 strbuf_reset(&buf);
1287                 if (!fast_forward_only &&
1288                     merge_remote_util(commit) &&
1289                     merge_remote_util(commit)->obj &&
1290                     merge_remote_util(commit)->obj->type == OBJ_TAG) {
1291                         option_edit = 1;
1292                         allow_fast_forward = 0;
1293                 }
1294         }
1295
1296         if (!use_strategies) {
1297                 if (!remoteheads->next)
1298                         add_strategies(pull_twohead, DEFAULT_TWOHEAD);
1299                 else
1300                         add_strategies(pull_octopus, DEFAULT_OCTOPUS);
1301         }
1302
1303         for (i = 0; i < use_strategies_nr; i++) {
1304                 if (use_strategies[i]->attr & NO_FAST_FORWARD)
1305                         allow_fast_forward = 0;
1306                 if (use_strategies[i]->attr & NO_TRIVIAL)
1307                         allow_trivial = 0;
1308         }
1309
1310         if (!remoteheads->next)
1311                 common = get_merge_bases(head_commit, remoteheads->item, 1);
1312         else {
1313                 struct commit_list *list = remoteheads;
1314                 commit_list_insert(head_commit, &list);
1315                 common = get_octopus_merge_bases(list);
1316                 free(list);
1317         }
1318
1319         update_ref("updating ORIG_HEAD", "ORIG_HEAD", head_commit->object.sha1,
1320                    NULL, 0, DIE_ON_ERR);
1321
1322         if (!common)
1323                 ; /* No common ancestors found. We need a real merge. */
1324         else if (!remoteheads->next && !common->next &&
1325                         common->item == remoteheads->item) {
1326                 /*
1327                  * If head can reach all the merge then we are up to date.
1328                  * but first the most common case of merging one remote.
1329                  */
1330                 finish_up_to_date("Already up-to-date.");
1331                 goto done;
1332         } else if (allow_fast_forward && !remoteheads->next &&
1333                         !common->next &&
1334                         !hashcmp(common->item->object.sha1, head_commit->object.sha1)) {
1335                 /* Again the most common case of merging one remote. */
1336                 struct strbuf msg = STRBUF_INIT;
1337                 struct commit *commit;
1338                 char hex[41];
1339
1340                 strcpy(hex, find_unique_abbrev(head_commit->object.sha1, DEFAULT_ABBREV));
1341
1342                 if (verbosity >= 0)
1343                         printf(_("Updating %s..%s\n"),
1344                                 hex,
1345                                 find_unique_abbrev(remoteheads->item->object.sha1,
1346                                 DEFAULT_ABBREV));
1347                 strbuf_addstr(&msg, "Fast-forward");
1348                 if (have_message)
1349                         strbuf_addstr(&msg,
1350                                 " (no commit created; -m option ignored)");
1351                 commit = remoteheads->item;
1352                 if (!commit) {
1353                         ret = 1;
1354                         goto done;
1355                 }
1356
1357                 if (checkout_fast_forward(head_commit->object.sha1,
1358                                           commit->object.sha1)) {
1359                         ret = 1;
1360                         goto done;
1361                 }
1362
1363                 finish(head_commit, commit->object.sha1, msg.buf);
1364                 drop_save();
1365                 goto done;
1366         } else if (!remoteheads->next && common->next)
1367                 ;
1368                 /*
1369                  * We are not doing octopus and not fast-forward.  Need
1370                  * a real merge.
1371                  */
1372         else if (!remoteheads->next && !common->next && option_commit) {
1373                 /*
1374                  * We are not doing octopus, not fast-forward, and have
1375                  * only one common.
1376                  */
1377                 refresh_cache(REFRESH_QUIET);
1378                 if (allow_trivial && !fast_forward_only) {
1379                         /* See if it is really trivial. */
1380                         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1381                         printf(_("Trying really trivial in-index merge...\n"));
1382                         if (!read_tree_trivial(common->item->object.sha1,
1383                                                head_commit->object.sha1,
1384                                                remoteheads->item->object.sha1)) {
1385                                 ret = merge_trivial(head_commit);
1386                                 goto done;
1387                         }
1388                         printf(_("Nope.\n"));
1389                 }
1390         } else {
1391                 /*
1392                  * An octopus.  If we can reach all the remote we are up
1393                  * to date.
1394                  */
1395                 int up_to_date = 1;
1396                 struct commit_list *j;
1397
1398                 for (j = remoteheads; j; j = j->next) {
1399                         struct commit_list *common_one;
1400
1401                         /*
1402                          * Here we *have* to calculate the individual
1403                          * merge_bases again, otherwise "git merge HEAD^
1404                          * HEAD^^" would be missed.
1405                          */
1406                         common_one = get_merge_bases(head_commit, j->item, 1);
1407                         if (hashcmp(common_one->item->object.sha1,
1408                                 j->item->object.sha1)) {
1409                                 up_to_date = 0;
1410                                 break;
1411                         }
1412                 }
1413                 if (up_to_date) {
1414                         finish_up_to_date("Already up-to-date. Yeeah!");
1415                         goto done;
1416                 }
1417         }
1418
1419         if (fast_forward_only)
1420                 die(_("Not possible to fast-forward, aborting."));
1421
1422         /* We are going to make a new commit. */
1423         git_committer_info(IDENT_ERROR_ON_NO_NAME);
1424
1425         /*
1426          * At this point, we need a real merge.  No matter what strategy
1427          * we use, it would operate on the index, possibly affecting the
1428          * working tree, and when resolved cleanly, have the desired
1429          * tree in the index -- this means that the index must be in
1430          * sync with the head commit.  The strategies are responsible
1431          * to ensure this.
1432          */
1433         if (use_strategies_nr == 1 ||
1434             /*
1435              * Stash away the local changes so that we can try more than one.
1436              */
1437             save_state(stash))
1438                 hashcpy(stash, null_sha1);
1439
1440         for (i = 0; i < use_strategies_nr; i++) {
1441                 int ret;
1442                 if (i) {
1443                         printf(_("Rewinding the tree to pristine...\n"));
1444                         restore_state(head_commit->object.sha1, stash);
1445                 }
1446                 if (use_strategies_nr != 1)
1447                         printf(_("Trying merge strategy %s...\n"),
1448                                 use_strategies[i]->name);
1449                 /*
1450                  * Remember which strategy left the state in the working
1451                  * tree.
1452                  */
1453                 wt_strategy = use_strategies[i]->name;
1454
1455                 ret = try_merge_strategy(use_strategies[i]->name,
1456                                          common, head_commit, head_arg);
1457                 if (!option_commit && !ret) {
1458                         merge_was_ok = 1;
1459                         /*
1460                          * This is necessary here just to avoid writing
1461                          * the tree, but later we will *not* exit with
1462                          * status code 1 because merge_was_ok is set.
1463                          */
1464                         ret = 1;
1465                 }
1466
1467                 if (ret) {
1468                         /*
1469                          * The backend exits with 1 when conflicts are
1470                          * left to be resolved, with 2 when it does not
1471                          * handle the given merge at all.
1472                          */
1473                         if (ret == 1) {
1474                                 int cnt = evaluate_result();
1475
1476                                 if (best_cnt <= 0 || cnt <= best_cnt) {
1477                                         best_strategy = use_strategies[i]->name;
1478                                         best_cnt = cnt;
1479                                 }
1480                         }
1481                         if (merge_was_ok)
1482                                 break;
1483                         else
1484                                 continue;
1485                 }
1486
1487                 /* Automerge succeeded. */
1488                 write_tree_trivial(result_tree);
1489                 automerge_was_ok = 1;
1490                 break;
1491         }
1492
1493         /*
1494          * If we have a resulting tree, that means the strategy module
1495          * auto resolved the merge cleanly.
1496          */
1497         if (automerge_was_ok) {
1498                 ret = finish_automerge(head_commit, common, result_tree,
1499                                        wt_strategy);
1500                 goto done;
1501         }
1502
1503         /*
1504          * Pick the result from the best strategy and have the user fix
1505          * it up.
1506          */
1507         if (!best_strategy) {
1508                 restore_state(head_commit->object.sha1, stash);
1509                 if (use_strategies_nr > 1)
1510                         fprintf(stderr,
1511                                 _("No merge strategy handled the merge.\n"));
1512                 else
1513                         fprintf(stderr, _("Merge with strategy %s failed.\n"),
1514                                 use_strategies[0]->name);
1515                 ret = 2;
1516                 goto done;
1517         } else if (best_strategy == wt_strategy)
1518                 ; /* We already have its result in the working tree. */
1519         else {
1520                 printf(_("Rewinding the tree to pristine...\n"));
1521                 restore_state(head_commit->object.sha1, stash);
1522                 printf(_("Using the %s to prepare resolving by hand.\n"),
1523                         best_strategy);
1524                 try_merge_strategy(best_strategy, common, head_commit, head_arg);
1525         }
1526
1527         if (squash)
1528                 finish(head_commit, NULL, NULL);
1529         else
1530                 write_merge_state();
1531
1532         if (merge_was_ok)
1533                 fprintf(stderr, _("Automatic merge went well; "
1534                         "stopped before committing as requested\n"));
1535         else
1536                 ret = suggest_conflicts(option_renormalize);
1537
1538 done:
1539         free(branch_to_free);
1540         return ret;
1541 }