builtin/pull.c

   1 /*
   2  * Builtin "git pull"
   3  *
   4  * Based on git-pull.sh by Junio C Hamano
   5  *
   6  * Fetch one or more remote refs and merge it/them into the current HEAD.
   7  */
   8 #include "cache.h"
   9 #include "builtin.h"
  10 #include "parse-options.h"
  11 #include "exec_cmd.h"
  12 #include "run-command.h"
  13 #include "sha1-array.h"
  14 #include "remote.h"
  15 #include "dir.h"
  16 #include "refs.h"
  17 #include "revision.h"
  18 #include "tempfile.h"
  19 #include "lockfile.h"
  20
  21 enum rebase_type {
  22         REBASE_INVALID = -1,
  23         REBASE_FALSE = 0,
  24         REBASE_TRUE,
  25         REBASE_PRESERVE,
  26         REBASE_INTERACTIVE
  27 };
  28
  29 /**
  30  * Parses the value of --rebase. If value is a false value, returns
  31  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  32  * "preserve", returns REBASE_PRESERVE. If value is a invalid value, dies with
  33  * a fatal error if fatal is true, otherwise returns REBASE_INVALID.
  34  */
  35 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  36                 int fatal)
  37 {
  38         int v = git_config_maybe_bool("pull.rebase", value);
  39
  40         if (!v)
  41                 return REBASE_FALSE;
  42         else if (v > 0)
  43                 return REBASE_TRUE;
  44         else if (!strcmp(value, "preserve"))
  45                 return REBASE_PRESERVE;
  46         else if (!strcmp(value, "interactive"))
  47                 return REBASE_INTERACTIVE;
  48
  49         if (fatal)
  50                 die(_("Invalid value for %s: %s"), key, value);
  51         else
  52                 error(_("Invalid value for %s: %s"), key, value);
  53
  54         return REBASE_INVALID;
  55 }
  56
  57 /**
  58  * Callback for --rebase, which parses arg with parse_config_rebase().
  59  */
  60 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  61 {
  62         enum rebase_type *value = opt->value;
  63
  64         if (arg)
  65                 *value = parse_config_rebase("--rebase", arg, 0);
  66         else
  67                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  68         return *value == REBASE_INVALID ? -1 : 0;
  69 }
  70
  71 static const char * const pull_usage[] = {
  72         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  73         NULL
  74 };
  75
  76 /* Shared options */
  77 static int opt_verbosity;
  78 static char *opt_progress;
  79
  80 /* Options passed to git-merge or git-rebase */
  81 static enum rebase_type opt_rebase = -1;
  82 static char *opt_diffstat;
  83 static char *opt_log;
  84 static char *opt_squash;
  85 static char *opt_commit;
  86 static char *opt_edit;
  87 static char *opt_ff;
  88 static char *opt_verify_signatures;
  89 static int opt_autostash = -1;
  90 static int config_autostash;
  91 static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
  92 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
  93 static char *opt_gpg_sign;
  94 static int opt_allow_unrelated_histories;
  95
  96 /* Options passed to git-fetch */
  97 static char *opt_all;
  98 static char *opt_append;
  99 static char *opt_upload_pack;
 100 static int opt_force;
 101 static char *opt_tags;
 102 static char *opt_prune;
 103 static char *opt_recurse_submodules;
 104 static char *max_children;
 105 static int opt_dry_run;
 106 static char *opt_keep;
 107 static char *opt_depth;
 108 static char *opt_unshallow;
 109 static char *opt_update_shallow;
 110 static char *opt_refmap;
 111
 112 static struct option pull_options[] = {
 113         /* Shared options */
 114         OPT__VERBOSITY(&opt_verbosity),
 115         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 116                 N_("force progress reporting"),
 117                 PARSE_OPT_NOARG),
 118
 119         /* Options passed to git-merge or git-rebase */
 120         OPT_GROUP(N_("Options related to merging")),
 121         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 122           "false|true|preserve|interactive",
 123           N_("incorporate changes by rebasing rather than merging"),
 124           PARSE_OPT_OPTARG, parse_opt_rebase },
 125         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 126                 N_("do not show a diffstat at the end of the merge"),
 127                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 128         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 129                 N_("show a diffstat at the end of the merge"),
 130                 PARSE_OPT_NOARG),
 131         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 132                 N_("(synonym to --stat)"),
 133                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 134         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 135                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 136                 PARSE_OPT_OPTARG),
 137         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 138                 N_("create a single commit instead of doing a merge"),
 139                 PARSE_OPT_NOARG),
 140         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 141                 N_("perform a commit if the merge succeeds (default)"),
 142                 PARSE_OPT_NOARG),
 143         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 144                 N_("edit message before committing"),
 145                 PARSE_OPT_NOARG),
 146         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 147                 N_("allow fast-forward"),
 148                 PARSE_OPT_NOARG),
 149         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 150                 N_("abort if fast-forward is not possible"),
 151                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 152         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 153                 N_("verify that the named commit has a valid GPG signature"),
 154                 PARSE_OPT_NOARG),
 155         OPT_BOOL(0, "autostash", &opt_autostash,
 156                 N_("automatically stash/stash pop before and after rebase")),
 157         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 158                 N_("merge strategy to use"),
 159                 0),
 160         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 161                 N_("option=value"),
 162                 N_("option for selected merge strategy"),
 163                 0),
 164         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 165                 N_("GPG sign commit"),
 166                 PARSE_OPT_OPTARG),
 167         OPT_SET_INT(0, "allow-unrelated-histories",
 168                     &opt_allow_unrelated_histories,
 169                     N_("allow merging unrelated histories"), 1),
 170
 171         /* Options passed to git-fetch */
 172         OPT_GROUP(N_("Options related to fetching")),
 173         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 174                 N_("fetch from all remotes"),
 175                 PARSE_OPT_NOARG),
 176         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 177                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 178                 PARSE_OPT_NOARG),
 179         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 180                 N_("path to upload pack on remote end"),
 181                 0),
 182         OPT__FORCE(&opt_force, N_("force overwrite of local branch")),
 183         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 184                 N_("fetch all tags and associated objects"),
 185                 PARSE_OPT_NOARG),
 186         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 187                 N_("prune remote-tracking branches no longer on remote"),
 188                 PARSE_OPT_NOARG),
 189         OPT_PASSTHRU(0, "recurse-submodules", &opt_recurse_submodules,
 190                 N_("on-demand"),
 191                 N_("control recursive fetching of submodules"),
 192                 PARSE_OPT_OPTARG),
 193         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 194                 N_("number of submodules pulled in parallel"),
 195                 PARSE_OPT_OPTARG),
 196         OPT_BOOL(0, "dry-run", &opt_dry_run,
 197                 N_("dry run")),
 198         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 199                 N_("keep downloaded pack"),
 200                 PARSE_OPT_NOARG),
 201         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 202                 N_("deepen history of shallow clone"),
 203                 0),
 204         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 205                 N_("convert to a complete repository"),
 206                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 207         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 208                 N_("accept refs that update .git/shallow"),
 209                 PARSE_OPT_NOARG),
 210         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 211                 N_("specify fetch refmap"),
 212                 PARSE_OPT_NONEG),
 213
 214         OPT_END()
 215 };
 216
 217 /**
 218  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 219  */
 220 static void argv_push_verbosity(struct argv_array *arr)
 221 {
 222         int verbosity;
 223
 224         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 225                 argv_array_push(arr, "-v");
 226
 227         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 228                 argv_array_push(arr, "-q");
 229 }
 230
 231 /**
 232  * Pushes "-f" switches into arr to match the opt_force level.
 233  */
 234 static void argv_push_force(struct argv_array *arr)
 235 {
 236         int force = opt_force;
 237         while (force-- > 0)
 238                 argv_array_push(arr, "-f");
 239 }
 240
 241 /**
 242  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 243  */
 244 static void set_reflog_message(int argc, const char **argv)
 245 {
 246         int i;
 247         struct strbuf msg = STRBUF_INIT;
 248
 249         for (i = 0; i < argc; i++) {
 250                 if (i)
 251                         strbuf_addch(&msg, ' ');
 252                 strbuf_addstr(&msg, argv[i]);
 253         }
 254
 255         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 256
 257         strbuf_release(&msg);
 258 }
 259
 260 /**
 261  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 262  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 263  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 264  * error.
 265  */
 266 static const char *config_get_ff(void)
 267 {
 268         const char *value;
 269
 270         if (git_config_get_value("pull.ff", &value))
 271                 return NULL;
 272
 273         switch (git_config_maybe_bool("pull.ff", value)) {
 274         case 0:
 275                 return "--no-ff";
 276         case 1:
 277                 return "--ff";
 278         }
 279
 280         if (!strcmp(value, "only"))
 281                 return "--ff-only";
 282
 283         die(_("Invalid value for pull.ff: %s"), value);
 284 }
 285
 286 /**
 287  * Returns the default configured value for --rebase. It first looks for the
 288  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 289  * branch, and if HEAD is detached or the configuration key does not exist,
 290  * looks for the value of "pull.rebase". If both configuration keys do not
 291  * exist, returns REBASE_FALSE.
 292  */
 293 static enum rebase_type config_get_rebase(void)
 294 {
 295         struct branch *curr_branch = branch_get("HEAD");
 296         const char *value;
 297
 298         if (curr_branch) {
 299                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 300
 301                 if (!git_config_get_value(key, &value)) {
 302                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 303                         free(key);
 304                         return ret;
 305                 }
 306
 307                 free(key);
 308         }
 309
 310         if (!git_config_get_value("pull.rebase", &value))
 311                 return parse_config_rebase("pull.rebase", value, 1);
 312
 313         return REBASE_FALSE;
 314 }
 315
 316 /**
 317  * Read config variables.
 318  */
 319 static int git_pull_config(const char *var, const char *value, void *cb)
 320 {
 321         if (!strcmp(var, "rebase.autostash")) {
 322                 config_autostash = git_config_bool(var, value);
 323                 return 0;
 324         }
 325         return git_default_config(var, value, cb);
 326 }
 327
 328 /**
 329  * Returns 1 if there are unstaged changes, 0 otherwise.
 330  */
 331 static int has_unstaged_changes(const char *prefix)
 332 {
 333         struct rev_info rev_info;
 334         int result;
 335
 336         init_revisions(&rev_info, prefix);
 337         DIFF_OPT_SET(&rev_info.diffopt, IGNORE_SUBMODULES);
 338         DIFF_OPT_SET(&rev_info.diffopt, QUICK);
 339         diff_setup_done(&rev_info.diffopt);
 340         result = run_diff_files(&rev_info, 0);
 341         return diff_result_code(&rev_info.diffopt, result);
 342 }
 343
 344 /**
 345  * Returns 1 if there are uncommitted changes, 0 otherwise.
 346  */
 347 static int has_uncommitted_changes(const char *prefix)
 348 {
 349         struct rev_info rev_info;
 350         int result;
 351
 352         if (is_cache_unborn())
 353                 return 0;
 354
 355         init_revisions(&rev_info, prefix);
 356         DIFF_OPT_SET(&rev_info.diffopt, IGNORE_SUBMODULES);
 357         DIFF_OPT_SET(&rev_info.diffopt, QUICK);
 358         add_head_to_pending(&rev_info);
 359         diff_setup_done(&rev_info.diffopt);
 360         result = run_diff_index(&rev_info, 1);
 361         return diff_result_code(&rev_info.diffopt, result);
 362 }
 363
 364 /**
 365  * If the work tree has unstaged or uncommitted changes, dies with the
 366  * appropriate message.
 367  */
 368 static void die_on_unclean_work_tree(const char *prefix)
 369 {
 370         struct lock_file *lock_file = xcalloc(1, sizeof(*lock_file));
 371         int do_die = 0;
 372
 373         hold_locked_index(lock_file, 0);
 374         refresh_cache(REFRESH_QUIET);
 375         update_index_if_able(&the_index, lock_file);
 376         rollback_lock_file(lock_file);
 377
 378         if (has_unstaged_changes(prefix)) {
 379                 error(_("Cannot pull with rebase: You have unstaged changes."));
 380                 do_die = 1;
 381         }
 382
 383         if (has_uncommitted_changes(prefix)) {
 384                 if (do_die)
 385                         error(_("Additionally, your index contains uncommitted changes."));
 386                 else
 387                         error(_("Cannot pull with rebase: Your index contains uncommitted changes."));
 388                 do_die = 1;
 389         }
 390
 391         if (do_die)
 392                 exit(1);
 393 }
 394
 395 /**
 396  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 397  * into merge_heads.
 398  */
 399 static void get_merge_heads(struct sha1_array *merge_heads)
 400 {
 401         const char *filename = git_path("FETCH_HEAD");
 402         FILE *fp;
 403         struct strbuf sb = STRBUF_INIT;
 404         unsigned char sha1[GIT_SHA1_RAWSZ];
 405
 406         if (!(fp = fopen(filename, "r")))
 407                 die_errno(_("could not open '%s' for reading"), filename);
 408         while (strbuf_getline_lf(&sb, fp) != EOF) {
 409                 if (get_sha1_hex(sb.buf, sha1))
 410                         continue;  /* invalid line: does not start with SHA1 */
 411                 if (starts_with(sb.buf + GIT_SHA1_HEXSZ, "\tnot-for-merge\t"))
 412                         continue;  /* ref is not-for-merge */
 413                 sha1_array_append(merge_heads, sha1);
 414         }
 415         fclose(fp);
 416         strbuf_release(&sb);
 417 }
 418
 419 /**
 420  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 421  * retrieve the name of the remote if the repository only has one remote.
 422  */
 423 static int get_only_remote(struct remote *remote, void *cb_data)
 424 {
 425         const char **remote_name = cb_data;
 426
 427         if (*remote_name)
 428                 return -1;
 429
 430         *remote_name = remote->name;
 431         return 0;
 432 }
 433
 434 /**
 435  * Dies with the appropriate reason for why there are no merge candidates:
 436  *
 437  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 438  *    up not fetching anything. This is usually because the user provided a
 439  *    wildcard refspec which had no matches on the remote end.
 440  *
 441  * 2. We fetched from a non-default remote, but didn't specify a branch to
 442  *    merge. We can't use the configured one because it applies to the default
 443  *    remote, thus the user must specify the branches to merge.
 444  *
 445  * 3. We fetched from the branch's or repo's default remote, but:
 446  *
 447  *    a. We are not on a branch, so there will never be a configured branch to
 448  *       merge with.
 449  *
 450  *    b. We are on a branch, but there is no configured branch to merge with.
 451  *
 452  * 4. We fetched from the branch's or repo's default remote, but the configured
 453  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 454  *    part of the configured fetch refspec.)
 455  */
 456 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 457 {
 458         struct branch *curr_branch = branch_get("HEAD");
 459         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 460
 461         if (*refspecs) {
 462                 if (opt_rebase)
 463                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 464                 else
 465                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 466                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 467                                         "matches on the remote end."));
 468         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 469                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 470                         "a branch. Because this is not the default configured remote\n"
 471                         "for your current branch, you must specify a branch on the command line."),
 472                         repo);
 473         } else if (!curr_branch) {
 474                 fprintf_ln(stderr, _("You are not currently on a branch."));
 475                 if (opt_rebase)
 476                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 477                 else
 478                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 479                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 480                 fprintf(stderr, "\n");
 481                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 482                 fprintf(stderr, "\n");
 483         } else if (!curr_branch->merge_nr) {
 484                 const char *remote_name = NULL;
 485
 486                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 487                         remote_name = _("<remote>");
 488
 489                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 490                 if (opt_rebase)
 491                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 492                 else
 493                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 494                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 495                 fprintf(stderr, "\n");
 496                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 497                 fprintf(stderr, "\n");
 498                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 499                 fprintf(stderr, "\n");
 500                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 501                                 remote_name, _("<branch>"), curr_branch->name);
 502         } else
 503                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 504                         "from the remote, but no such ref was fetched."),
 505                         *curr_branch->merge_name);
 506         exit(1);
 507 }
 508
 509 /**
 510  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 511  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 512  * is not provided in argv, it is set to NULL.
 513  */
 514 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 515                 const char ***refspecs)
 516 {
 517         if (argc > 0) {
 518                 *repo = *argv++;
 519                 argc--;
 520         } else
 521                 *repo = NULL;
 522         *refspecs = argv;
 523 }
 524
 525 /**
 526  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 527  * repository and refspecs to fetch, or NULL if they are not provided.
 528  */
 529 static int run_fetch(const char *repo, const char **refspecs)
 530 {
 531         struct argv_array args = ARGV_ARRAY_INIT;
 532         int ret;
 533
 534         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 535
 536         /* Shared options */
 537         argv_push_verbosity(&args);
 538         if (opt_progress)
 539                 argv_array_push(&args, opt_progress);
 540
 541         /* Options passed to git-fetch */
 542         if (opt_all)
 543                 argv_array_push(&args, opt_all);
 544         if (opt_append)
 545                 argv_array_push(&args, opt_append);
 546         if (opt_upload_pack)
 547                 argv_array_push(&args, opt_upload_pack);
 548         argv_push_force(&args);
 549         if (opt_tags)
 550                 argv_array_push(&args, opt_tags);
 551         if (opt_prune)
 552                 argv_array_push(&args, opt_prune);
 553         if (opt_recurse_submodules)
 554                 argv_array_push(&args, opt_recurse_submodules);
 555         if (max_children)
 556                 argv_array_push(&args, max_children);
 557         if (opt_dry_run)
 558                 argv_array_push(&args, "--dry-run");
 559         if (opt_keep)
 560                 argv_array_push(&args, opt_keep);
 561         if (opt_depth)
 562                 argv_array_push(&args, opt_depth);
 563         if (opt_unshallow)
 564                 argv_array_push(&args, opt_unshallow);
 565         if (opt_update_shallow)
 566                 argv_array_push(&args, opt_update_shallow);
 567         if (opt_refmap)
 568                 argv_array_push(&args, opt_refmap);
 569
 570         if (repo) {
 571                 argv_array_push(&args, repo);
 572                 argv_array_pushv(&args, refspecs);
 573         } else if (*refspecs)
 574                 die("BUG: refspecs without repo?");
 575         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 576         argv_array_clear(&args);
 577         return ret;
 578 }
 579
 580 /**
 581  * "Pulls into void" by branching off merge_head.
 582  */
 583 static int pull_into_void(const unsigned char *merge_head,
 584                 const unsigned char *curr_head)
 585 {
 586         /*
 587          * Two-way merge: we treat the index as based on an empty tree,
 588          * and try to fast-forward to HEAD. This ensures we will not lose
 589          * index/worktree changes that the user already made on the unborn
 590          * branch.
 591          */
 592         if (checkout_fast_forward(EMPTY_TREE_SHA1_BIN, merge_head, 0))
 593                 return 1;
 594
 595         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 596                 return 1;
 597
 598         return 0;
 599 }
 600
 601 /**
 602  * Runs git-merge, returning its exit status.
 603  */
 604 static int run_merge(void)
 605 {
 606         int ret;
 607         struct argv_array args = ARGV_ARRAY_INIT;
 608
 609         argv_array_pushl(&args, "merge", NULL);
 610
 611         /* Shared options */
 612         argv_push_verbosity(&args);
 613         if (opt_progress)
 614                 argv_array_push(&args, opt_progress);
 615
 616         /* Options passed to git-merge */
 617         if (opt_diffstat)
 618                 argv_array_push(&args, opt_diffstat);
 619         if (opt_log)
 620                 argv_array_push(&args, opt_log);
 621         if (opt_squash)
 622                 argv_array_push(&args, opt_squash);
 623         if (opt_commit)
 624                 argv_array_push(&args, opt_commit);
 625         if (opt_edit)
 626                 argv_array_push(&args, opt_edit);
 627         if (opt_ff)
 628                 argv_array_push(&args, opt_ff);
 629         if (opt_verify_signatures)
 630                 argv_array_push(&args, opt_verify_signatures);
 631         argv_array_pushv(&args, opt_strategies.argv);
 632         argv_array_pushv(&args, opt_strategy_opts.argv);
 633         if (opt_gpg_sign)
 634                 argv_array_push(&args, opt_gpg_sign);
 635         if (opt_allow_unrelated_histories > 0)
 636                 argv_array_push(&args, "--allow-unrelated-histories");
 637
 638         argv_array_push(&args, "FETCH_HEAD");
 639         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 640         argv_array_clear(&args);
 641         return ret;
 642 }
 643
 644 /**
 645  * Returns remote's upstream branch for the current branch. If remote is NULL,
 646  * the current branch's configured default remote is used. Returns NULL if
 647  * `remote` does not name a valid remote, HEAD does not point to a branch,
 648  * remote is not the branch's configured remote or the branch does not have any
 649  * configured upstream branch.
 650  */
 651 static const char *get_upstream_branch(const char *remote)
 652 {
 653         struct remote *rm;
 654         struct branch *curr_branch;
 655         const char *curr_branch_remote;
 656
 657         rm = remote_get(remote);
 658         if (!rm)
 659                 return NULL;
 660
 661         curr_branch = branch_get("HEAD");
 662         if (!curr_branch)
 663                 return NULL;
 664
 665         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 666         assert(curr_branch_remote);
 667
 668         if (strcmp(curr_branch_remote, rm->name))
 669                 return NULL;
 670
 671         return branch_get_upstream(curr_branch, NULL);
 672 }
 673
 674 /**
 675  * Derives the remote tracking branch from the remote and refspec.
 676  *
 677  * FIXME: The current implementation assumes the default mapping of
 678  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 679  */
 680 static const char *get_tracking_branch(const char *remote, const char *refspec)
 681 {
 682         struct refspec *spec;
 683         const char *spec_src;
 684         const char *merge_branch;
 685
 686         spec = parse_fetch_refspec(1, &refspec);
 687         spec_src = spec->src;
 688         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 689                 spec_src = "HEAD";
 690         else if (skip_prefix(spec_src, "heads/", &spec_src))
 691                 ;
 692         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 693                 ;
 694         else if (starts_with(spec_src, "refs/") ||
 695                 starts_with(spec_src, "tags/") ||
 696                 starts_with(spec_src, "remotes/"))
 697                 spec_src = "";
 698
 699         if (*spec_src) {
 700                 if (!strcmp(remote, "."))
 701                         merge_branch = mkpath("refs/heads/%s", spec_src);
 702                 else
 703                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 704         } else
 705                 merge_branch = NULL;
 706
 707         free_refspec(1, spec);
 708         return merge_branch;
 709 }
 710
 711 /**
 712  * Given the repo and refspecs, sets fork_point to the point at which the
 713  * current branch forked from its remote tracking branch. Returns 0 on success,
 714  * -1 on failure.
 715  */
 716 static int get_rebase_fork_point(unsigned char *fork_point, const char *repo,
 717                 const char *refspec)
 718 {
 719         int ret;
 720         struct branch *curr_branch;
 721         const char *remote_branch;
 722         struct child_process cp = CHILD_PROCESS_INIT;
 723         struct strbuf sb = STRBUF_INIT;
 724
 725         curr_branch = branch_get("HEAD");
 726         if (!curr_branch)
 727                 return -1;
 728
 729         if (refspec)
 730                 remote_branch = get_tracking_branch(repo, refspec);
 731         else
 732                 remote_branch = get_upstream_branch(repo);
 733
 734         if (!remote_branch)
 735                 return -1;
 736
 737         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 738                         remote_branch, curr_branch->name, NULL);
 739         cp.no_stdin = 1;
 740         cp.no_stderr = 1;
 741         cp.git_cmd = 1;
 742
 743         ret = capture_command(&cp, &sb, GIT_SHA1_HEXSZ);
 744         if (ret)
 745                 goto cleanup;
 746
 747         ret = get_sha1_hex(sb.buf, fork_point);
 748         if (ret)
 749                 goto cleanup;
 750
 751 cleanup:
 752         strbuf_release(&sb);
 753         return ret ? -1 : 0;
 754 }
 755
 756 /**
 757  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 758  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 759  */
 760 static int get_octopus_merge_base(unsigned char *merge_base,
 761                 const unsigned char *curr_head,
 762                 const unsigned char *merge_head,
 763                 const unsigned char *fork_point)
 764 {
 765         struct commit_list *revs = NULL, *result;
 766
 767         commit_list_insert(lookup_commit_reference(curr_head), &revs);
 768         commit_list_insert(lookup_commit_reference(merge_head), &revs);
 769         if (!is_null_sha1(fork_point))
 770                 commit_list_insert(lookup_commit_reference(fork_point), &revs);
 771
 772         result = reduce_heads(get_octopus_merge_bases(revs));
 773         free_commit_list(revs);
 774         if (!result)
 775                 return 1;
 776
 777         hashcpy(merge_base, result->item->object.oid.hash);
 778         return 0;
 779 }
 780
 781 /**
 782  * Given the current HEAD SHA1, the merge head returned from git-fetch and the
 783  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 784  * appropriate arguments and returns its exit status.
 785  */
 786 static int run_rebase(const unsigned char *curr_head,
 787                 const unsigned char *merge_head,
 788                 const unsigned char *fork_point)
 789 {
 790         int ret;
 791         unsigned char oct_merge_base[GIT_SHA1_RAWSZ];
 792         struct argv_array args = ARGV_ARRAY_INIT;
 793
 794         if (!get_octopus_merge_base(oct_merge_base, curr_head, merge_head, fork_point))
 795                 if (!is_null_sha1(fork_point) && !hashcmp(oct_merge_base, fork_point))
 796                         fork_point = NULL;
 797
 798         argv_array_push(&args, "rebase");
 799
 800         /* Shared options */
 801         argv_push_verbosity(&args);
 802
 803         /* Options passed to git-rebase */
 804         if (opt_rebase == REBASE_PRESERVE)
 805                 argv_array_push(&args, "--preserve-merges");
 806         else if (opt_rebase == REBASE_INTERACTIVE)
 807                 argv_array_push(&args, "--interactive");
 808         if (opt_diffstat)
 809                 argv_array_push(&args, opt_diffstat);
 810         argv_array_pushv(&args, opt_strategies.argv);
 811         argv_array_pushv(&args, opt_strategy_opts.argv);
 812         if (opt_gpg_sign)
 813                 argv_array_push(&args, opt_gpg_sign);
 814         if (opt_autostash == 0)
 815                 argv_array_push(&args, "--no-autostash");
 816         else if (opt_autostash == 1)
 817                 argv_array_push(&args, "--autostash");
 818
 819         argv_array_push(&args, "--onto");
 820         argv_array_push(&args, sha1_to_hex(merge_head));
 821
 822         if (fork_point && !is_null_sha1(fork_point))
 823                 argv_array_push(&args, sha1_to_hex(fork_point));
 824         else
 825                 argv_array_push(&args, sha1_to_hex(merge_head));
 826
 827         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 828         argv_array_clear(&args);
 829         return ret;
 830 }
 831
 832 int cmd_pull(int argc, const char **argv, const char *prefix)
 833 {
 834         const char *repo, **refspecs;
 835         struct sha1_array merge_heads = SHA1_ARRAY_INIT;
 836         unsigned char orig_head[GIT_SHA1_RAWSZ], curr_head[GIT_SHA1_RAWSZ];
 837         unsigned char rebase_fork_point[GIT_SHA1_RAWSZ];
 838
 839         if (!getenv("GIT_REFLOG_ACTION"))
 840                 set_reflog_message(argc, argv);
 841
 842         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 843
 844         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 845
 846         if (!opt_ff)
 847                 opt_ff = xstrdup_or_null(config_get_ff());
 848
 849         if (opt_rebase < 0)
 850                 opt_rebase = config_get_rebase();
 851
 852         git_config(git_pull_config, NULL);
 853
 854         if (read_cache_unmerged())
 855                 die_resolve_conflict("Pull");
 856
 857         if (file_exists(git_path("MERGE_HEAD")))
 858                 die_conclude_merge();
 859
 860         if (get_sha1("HEAD", orig_head))
 861                 hashclr(orig_head);
 862
 863         if (!opt_rebase && opt_autostash != -1)
 864                 die(_("--[no-]autostash option is only valid with --rebase."));
 865
 866         if (opt_rebase) {
 867                 int autostash = config_autostash;
 868                 if (opt_autostash != -1)
 869                         autostash = opt_autostash;
 870
 871                 if (is_null_sha1(orig_head) && !is_cache_unborn())
 872                         die(_("Updating an unborn branch with changes added to the index."));
 873
 874                 if (!autostash)
 875                         die_on_unclean_work_tree(prefix);
 876
 877                 if (get_rebase_fork_point(rebase_fork_point, repo, *refspecs))
 878                         hashclr(rebase_fork_point);
 879         }
 880
 881         if (run_fetch(repo, refspecs))
 882                 return 1;
 883
 884         if (opt_dry_run)
 885                 return 0;
 886
 887         if (get_sha1("HEAD", curr_head))
 888                 hashclr(curr_head);
 889
 890         if (!is_null_sha1(orig_head) && !is_null_sha1(curr_head) &&
 891                         hashcmp(orig_head, curr_head)) {
 892                 /*
 893                  * The fetch involved updating the current branch.
 894                  *
 895                  * The working tree and the index file are still based on
 896                  * orig_head commit, but we are merging into curr_head.
 897                  * Update the working tree to match curr_head.
 898                  */
 899
 900                 warning(_("fetch updated the current branch head.\n"
 901                         "fast-forwarding your working tree from\n"
 902                         "commit %s."), sha1_to_hex(orig_head));
 903
 904                 if (checkout_fast_forward(orig_head, curr_head, 0))
 905                         die(_("Cannot fast-forward your working tree.\n"
 906                                 "After making sure that you saved anything precious from\n"
 907                                 "$ git diff %s\n"
 908                                 "output, run\n"
 909                                 "$ git reset --hard\n"
 910                                 "to recover."), sha1_to_hex(orig_head));
 911         }
 912
 913         get_merge_heads(&merge_heads);
 914
 915         if (!merge_heads.nr)
 916                 die_no_merge_candidates(repo, refspecs);
 917
 918         if (is_null_sha1(orig_head)) {
 919                 if (merge_heads.nr > 1)
 920                         die(_("Cannot merge multiple branches into empty head."));
 921                 return pull_into_void(*merge_heads.sha1, curr_head);
 922         } else if (opt_rebase) {
 923                 if (merge_heads.nr > 1)
 924                         die(_("Cannot rebase onto multiple branches."));
 925                 return run_rebase(curr_head, *merge_heads.sha1, rebase_fork_point);
 926         } else
 927                 return run_merge();
 928 }