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 #define USE_THE_INDEX_COMPATIBILITY_MACROS
   9 #include "cache.h"
  10 #include "config.h"
  11 #include "builtin.h"
  12 #include "parse-options.h"
  13 #include "exec-cmd.h"
  14 #include "run-command.h"
  15 #include "sha1-array.h"
  16 #include "remote.h"
  17 #include "dir.h"
  18 #include "refs.h"
  19 #include "refspec.h"
  20 #include "revision.h"
  21 #include "submodule.h"
  22 #include "submodule-config.h"
  23 #include "tempfile.h"
  24 #include "lockfile.h"
  25 #include "wt-status.h"
  26 #include "commit-reach.h"
  27 #include "sequencer.h"
  28
  29 enum rebase_type {
  30         REBASE_INVALID = -1,
  31         REBASE_FALSE = 0,
  32         REBASE_TRUE,
  33         REBASE_PRESERVE,
  34         REBASE_MERGES,
  35         REBASE_INTERACTIVE
  36 };
  37
  38 /**
  39  * Parses the value of --rebase. If value is a false value, returns
  40  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  41  * "merges", returns REBASE_MERGES. If value is "preserve", returns
  42  * REBASE_PRESERVE. If value is a invalid value, dies with a fatal error if
  43  * fatal is true, otherwise returns REBASE_INVALID.
  44  */
  45 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  46                 int fatal)
  47 {
  48         int v = git_parse_maybe_bool(value);
  49
  50         if (!v)
  51                 return REBASE_FALSE;
  52         else if (v > 0)
  53                 return REBASE_TRUE;
  54         else if (!strcmp(value, "preserve") || !strcmp(value, "p"))
  55                 return REBASE_PRESERVE;
  56         else if (!strcmp(value, "merges") || !strcmp(value, "m"))
  57                 return REBASE_MERGES;
  58         else if (!strcmp(value, "interactive") || !strcmp(value, "i"))
  59                 return REBASE_INTERACTIVE;
  60         /*
  61          * Please update _git_config() in git-completion.bash when you
  62          * add new rebase modes.
  63          */
  64
  65         if (fatal)
  66                 die(_("Invalid value for %s: %s"), key, value);
  67         else
  68                 error(_("Invalid value for %s: %s"), key, value);
  69
  70         return REBASE_INVALID;
  71 }
  72
  73 /**
  74  * Callback for --rebase, which parses arg with parse_config_rebase().
  75  */
  76 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  77 {
  78         enum rebase_type *value = opt->value;
  79
  80         if (arg)
  81                 *value = parse_config_rebase("--rebase", arg, 0);
  82         else
  83                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  84         return *value == REBASE_INVALID ? -1 : 0;
  85 }
  86
  87 static const char * const pull_usage[] = {
  88         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  89         NULL
  90 };
  91
  92 /* Shared options */
  93 static int opt_verbosity;
  94 static char *opt_progress;
  95 static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
  96
  97 /* Options passed to git-merge or git-rebase */
  98 static enum rebase_type opt_rebase = -1;
  99 static char *opt_diffstat;
 100 static char *opt_log;
 101 static char *opt_signoff;
 102 static char *opt_squash;
 103 static char *opt_commit;
 104 static char *opt_edit;
 105 static char *cleanup_arg;
 106 static char *opt_ff;
 107 static char *opt_verify_signatures;
 108 static int opt_autostash = -1;
 109 static int config_autostash;
 110 static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
 111 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
 112 static char *opt_gpg_sign;
 113 static int opt_allow_unrelated_histories;
 114
 115 /* Options passed to git-fetch */
 116 static char *opt_all;
 117 static char *opt_append;
 118 static char *opt_upload_pack;
 119 static int opt_force;
 120 static char *opt_tags;
 121 static char *opt_prune;
 122 static char *max_children;
 123 static int opt_dry_run;
 124 static char *opt_keep;
 125 static char *opt_depth;
 126 static char *opt_unshallow;
 127 static char *opt_update_shallow;
 128 static char *opt_refmap;
 129 static char *opt_ipv4;
 130 static char *opt_ipv6;
 131
 132 static struct option pull_options[] = {
 133         /* Shared options */
 134         OPT__VERBOSITY(&opt_verbosity),
 135         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 136                 N_("force progress reporting"),
 137                 PARSE_OPT_NOARG),
 138         { OPTION_CALLBACK, 0, "recurse-submodules",
 139                    &recurse_submodules, N_("on-demand"),
 140                    N_("control for recursive fetching of submodules"),
 141                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules },
 142
 143         /* Options passed to git-merge or git-rebase */
 144         OPT_GROUP(N_("Options related to merging")),
 145         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 146           "(false|true|merges|preserve|interactive)",
 147           N_("incorporate changes by rebasing rather than merging"),
 148           PARSE_OPT_OPTARG, parse_opt_rebase },
 149         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 150                 N_("do not show a diffstat at the end of the merge"),
 151                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 152         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 153                 N_("show a diffstat at the end of the merge"),
 154                 PARSE_OPT_NOARG),
 155         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 156                 N_("(synonym to --stat)"),
 157                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 158         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 159                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 160                 PARSE_OPT_OPTARG),
 161         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 162                 N_("add Signed-off-by:"),
 163                 PARSE_OPT_OPTARG),
 164         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 165                 N_("create a single commit instead of doing a merge"),
 166                 PARSE_OPT_NOARG),
 167         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 168                 N_("perform a commit if the merge succeeds (default)"),
 169                 PARSE_OPT_NOARG),
 170         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 171                 N_("edit message before committing"),
 172                 PARSE_OPT_NOARG),
 173         OPT_CLEANUP(&cleanup_arg),
 174         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 175                 N_("allow fast-forward"),
 176                 PARSE_OPT_NOARG),
 177         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 178                 N_("abort if fast-forward is not possible"),
 179                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 180         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 181                 N_("verify that the named commit has a valid GPG signature"),
 182                 PARSE_OPT_NOARG),
 183         OPT_BOOL(0, "autostash", &opt_autostash,
 184                 N_("automatically stash/stash pop before and after rebase")),
 185         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 186                 N_("merge strategy to use"),
 187                 0),
 188         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 189                 N_("option=value"),
 190                 N_("option for selected merge strategy"),
 191                 0),
 192         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 193                 N_("GPG sign commit"),
 194                 PARSE_OPT_OPTARG),
 195         OPT_SET_INT(0, "allow-unrelated-histories",
 196                     &opt_allow_unrelated_histories,
 197                     N_("allow merging unrelated histories"), 1),
 198
 199         /* Options passed to git-fetch */
 200         OPT_GROUP(N_("Options related to fetching")),
 201         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 202                 N_("fetch from all remotes"),
 203                 PARSE_OPT_NOARG),
 204         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 205                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 206                 PARSE_OPT_NOARG),
 207         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 208                 N_("path to upload pack on remote end"),
 209                 0),
 210         OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),
 211         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 212                 N_("fetch all tags and associated objects"),
 213                 PARSE_OPT_NOARG),
 214         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 215                 N_("prune remote-tracking branches no longer on remote"),
 216                 PARSE_OPT_NOARG),
 217         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 218                 N_("number of submodules pulled in parallel"),
 219                 PARSE_OPT_OPTARG),
 220         OPT_BOOL(0, "dry-run", &opt_dry_run,
 221                 N_("dry run")),
 222         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 223                 N_("keep downloaded pack"),
 224                 PARSE_OPT_NOARG),
 225         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 226                 N_("deepen history of shallow clone"),
 227                 0),
 228         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 229                 N_("convert to a complete repository"),
 230                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 231         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 232                 N_("accept refs that update .git/shallow"),
 233                 PARSE_OPT_NOARG),
 234         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 235                 N_("specify fetch refmap"),
 236                 PARSE_OPT_NONEG),
 237         OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,
 238                 N_("use IPv4 addresses only"),
 239                 PARSE_OPT_NOARG),
 240         OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 241                 N_("use IPv6 addresses only"),
 242                 PARSE_OPT_NOARG),
 243
 244         OPT_END()
 245 };
 246
 247 /**
 248  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 249  */
 250 static void argv_push_verbosity(struct argv_array *arr)
 251 {
 252         int verbosity;
 253
 254         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 255                 argv_array_push(arr, "-v");
 256
 257         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 258                 argv_array_push(arr, "-q");
 259 }
 260
 261 /**
 262  * Pushes "-f" switches into arr to match the opt_force level.
 263  */
 264 static void argv_push_force(struct argv_array *arr)
 265 {
 266         int force = opt_force;
 267         while (force-- > 0)
 268                 argv_array_push(arr, "-f");
 269 }
 270
 271 /**
 272  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 273  */
 274 static void set_reflog_message(int argc, const char **argv)
 275 {
 276         int i;
 277         struct strbuf msg = STRBUF_INIT;
 278
 279         for (i = 0; i < argc; i++) {
 280                 if (i)
 281                         strbuf_addch(&msg, ' ');
 282                 strbuf_addstr(&msg, argv[i]);
 283         }
 284
 285         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 286
 287         strbuf_release(&msg);
 288 }
 289
 290 /**
 291  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 292  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 293  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 294  * error.
 295  */
 296 static const char *config_get_ff(void)
 297 {
 298         const char *value;
 299
 300         if (git_config_get_value("pull.ff", &value))
 301                 return NULL;
 302
 303         switch (git_parse_maybe_bool(value)) {
 304         case 0:
 305                 return "--no-ff";
 306         case 1:
 307                 return "--ff";
 308         }
 309
 310         if (!strcmp(value, "only"))
 311                 return "--ff-only";
 312
 313         die(_("Invalid value for pull.ff: %s"), value);
 314 }
 315
 316 /**
 317  * Returns the default configured value for --rebase. It first looks for the
 318  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 319  * branch, and if HEAD is detached or the configuration key does not exist,
 320  * looks for the value of "pull.rebase". If both configuration keys do not
 321  * exist, returns REBASE_FALSE.
 322  */
 323 static enum rebase_type config_get_rebase(void)
 324 {
 325         struct branch *curr_branch = branch_get("HEAD");
 326         const char *value;
 327
 328         if (curr_branch) {
 329                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 330
 331                 if (!git_config_get_value(key, &value)) {
 332                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 333                         free(key);
 334                         return ret;
 335                 }
 336
 337                 free(key);
 338         }
 339
 340         if (!git_config_get_value("pull.rebase", &value))
 341                 return parse_config_rebase("pull.rebase", value, 1);
 342
 343         return REBASE_FALSE;
 344 }
 345
 346 /**
 347  * Read config variables.
 348  */
 349 static int git_pull_config(const char *var, const char *value, void *cb)
 350 {
 351         if (!strcmp(var, "rebase.autostash")) {
 352                 config_autostash = git_config_bool(var, value);
 353                 return 0;
 354         } else if (!strcmp(var, "submodule.recurse")) {
 355                 recurse_submodules = git_config_bool(var, value) ?
 356                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 357                 return 0;
 358         }
 359         return git_default_config(var, value, cb);
 360 }
 361
 362 /**
 363  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 364  * into merge_heads.
 365  */
 366 static void get_merge_heads(struct oid_array *merge_heads)
 367 {
 368         const char *filename = git_path_fetch_head(the_repository);
 369         FILE *fp;
 370         struct strbuf sb = STRBUF_INIT;
 371         struct object_id oid;
 372
 373         fp = xfopen(filename, "r");
 374         while (strbuf_getline_lf(&sb, fp) != EOF) {
 375                 const char *p;
 376                 if (parse_oid_hex(sb.buf, &oid, &p))
 377                         continue;  /* invalid line: does not start with object ID */
 378                 if (starts_with(p, "\tnot-for-merge\t"))
 379                         continue;  /* ref is not-for-merge */
 380                 oid_array_append(merge_heads, &oid);
 381         }
 382         fclose(fp);
 383         strbuf_release(&sb);
 384 }
 385
 386 /**
 387  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 388  * retrieve the name of the remote if the repository only has one remote.
 389  */
 390 static int get_only_remote(struct remote *remote, void *cb_data)
 391 {
 392         const char **remote_name = cb_data;
 393
 394         if (*remote_name)
 395                 return -1;
 396
 397         *remote_name = remote->name;
 398         return 0;
 399 }
 400
 401 /**
 402  * Dies with the appropriate reason for why there are no merge candidates:
 403  *
 404  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 405  *    up not fetching anything. This is usually because the user provided a
 406  *    wildcard refspec which had no matches on the remote end.
 407  *
 408  * 2. We fetched from a non-default remote, but didn't specify a branch to
 409  *    merge. We can't use the configured one because it applies to the default
 410  *    remote, thus the user must specify the branches to merge.
 411  *
 412  * 3. We fetched from the branch's or repo's default remote, but:
 413  *
 414  *    a. We are not on a branch, so there will never be a configured branch to
 415  *       merge with.
 416  *
 417  *    b. We are on a branch, but there is no configured branch to merge with.
 418  *
 419  * 4. We fetched from the branch's or repo's default remote, but the configured
 420  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 421  *    part of the configured fetch refspec.)
 422  */
 423 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 424 {
 425         struct branch *curr_branch = branch_get("HEAD");
 426         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 427
 428         if (*refspecs) {
 429                 if (opt_rebase)
 430                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 431                 else
 432                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 433                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 434                                         "matches on the remote end."));
 435         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 436                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 437                         "a branch. Because this is not the default configured remote\n"
 438                         "for your current branch, you must specify a branch on the command line."),
 439                         repo);
 440         } else if (!curr_branch) {
 441                 fprintf_ln(stderr, _("You are not currently on a branch."));
 442                 if (opt_rebase)
 443                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 444                 else
 445                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 446                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 447                 fprintf(stderr, "\n");
 448                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 449                 fprintf(stderr, "\n");
 450         } else if (!curr_branch->merge_nr) {
 451                 const char *remote_name = NULL;
 452
 453                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 454                         remote_name = _("<remote>");
 455
 456                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 457                 if (opt_rebase)
 458                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 459                 else
 460                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 461                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 462                 fprintf(stderr, "\n");
 463                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 464                 fprintf(stderr, "\n");
 465                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 466                 fprintf(stderr, "\n");
 467                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 468                                 remote_name, _("<branch>"), curr_branch->name);
 469         } else
 470                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 471                         "from the remote, but no such ref was fetched."),
 472                         *curr_branch->merge_name);
 473         exit(1);
 474 }
 475
 476 /**
 477  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 478  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 479  * is not provided in argv, it is set to NULL.
 480  */
 481 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 482                 const char ***refspecs)
 483 {
 484         if (argc > 0) {
 485                 *repo = *argv++;
 486                 argc--;
 487         } else
 488                 *repo = NULL;
 489         *refspecs = argv;
 490 }
 491
 492 /**
 493  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 494  * repository and refspecs to fetch, or NULL if they are not provided.
 495  */
 496 static int run_fetch(const char *repo, const char **refspecs)
 497 {
 498         struct argv_array args = ARGV_ARRAY_INIT;
 499         int ret;
 500
 501         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 502
 503         /* Shared options */
 504         argv_push_verbosity(&args);
 505         if (opt_progress)
 506                 argv_array_push(&args, opt_progress);
 507
 508         /* Options passed to git-fetch */
 509         if (opt_all)
 510                 argv_array_push(&args, opt_all);
 511         if (opt_append)
 512                 argv_array_push(&args, opt_append);
 513         if (opt_upload_pack)
 514                 argv_array_push(&args, opt_upload_pack);
 515         argv_push_force(&args);
 516         if (opt_tags)
 517                 argv_array_push(&args, opt_tags);
 518         if (opt_prune)
 519                 argv_array_push(&args, opt_prune);
 520         if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
 521                 switch (recurse_submodules) {
 522                 case RECURSE_SUBMODULES_ON:
 523                         argv_array_push(&args, "--recurse-submodules=on");
 524                         break;
 525                 case RECURSE_SUBMODULES_OFF:
 526                         argv_array_push(&args, "--recurse-submodules=no");
 527                         break;
 528                 case RECURSE_SUBMODULES_ON_DEMAND:
 529                         argv_array_push(&args, "--recurse-submodules=on-demand");
 530                         break;
 531                 default:
 532                         BUG("submodule recursion option not understood");
 533                 }
 534         if (max_children)
 535                 argv_array_push(&args, max_children);
 536         if (opt_dry_run)
 537                 argv_array_push(&args, "--dry-run");
 538         if (opt_keep)
 539                 argv_array_push(&args, opt_keep);
 540         if (opt_depth)
 541                 argv_array_push(&args, opt_depth);
 542         if (opt_unshallow)
 543                 argv_array_push(&args, opt_unshallow);
 544         if (opt_update_shallow)
 545                 argv_array_push(&args, opt_update_shallow);
 546         if (opt_refmap)
 547                 argv_array_push(&args, opt_refmap);
 548         if (opt_ipv4)
 549                 argv_array_push(&args, opt_ipv4);
 550         if (opt_ipv6)
 551                 argv_array_push(&args, opt_ipv6);
 552
 553         if (repo) {
 554                 argv_array_push(&args, repo);
 555                 argv_array_pushv(&args, refspecs);
 556         } else if (*refspecs)
 557                 BUG("refspecs without repo?");
 558         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 559         argv_array_clear(&args);
 560         return ret;
 561 }
 562
 563 /**
 564  * "Pulls into void" by branching off merge_head.
 565  */
 566 static int pull_into_void(const struct object_id *merge_head,
 567                 const struct object_id *curr_head)
 568 {
 569         if (opt_verify_signatures) {
 570                 struct commit *commit;
 571
 572                 commit = lookup_commit(the_repository, merge_head);
 573                 if (!commit)
 574                         die(_("unable to access commit %s"),
 575                             oid_to_hex(merge_head));
 576
 577                 verify_merge_signature(commit, opt_verbosity);
 578         }
 579
 580         /*
 581          * Two-way merge: we treat the index as based on an empty tree,
 582          * and try to fast-forward to HEAD. This ensures we will not lose
 583          * index/worktree changes that the user already made on the unborn
 584          * branch.
 585          */
 586         if (checkout_fast_forward(the_repository,
 587                                   the_hash_algo->empty_tree,
 588                                   merge_head, 0))
 589                 return 1;
 590
 591         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 592                 return 1;
 593
 594         return 0;
 595 }
 596
 597 static int rebase_submodules(void)
 598 {
 599         struct child_process cp = CHILD_PROCESS_INIT;
 600
 601         cp.git_cmd = 1;
 602         cp.no_stdin = 1;
 603         argv_array_pushl(&cp.args, "submodule", "update",
 604                                    "--recursive", "--rebase", NULL);
 605         argv_push_verbosity(&cp.args);
 606
 607         return run_command(&cp);
 608 }
 609
 610 static int update_submodules(void)
 611 {
 612         struct child_process cp = CHILD_PROCESS_INIT;
 613
 614         cp.git_cmd = 1;
 615         cp.no_stdin = 1;
 616         argv_array_pushl(&cp.args, "submodule", "update",
 617                                    "--recursive", "--checkout", NULL);
 618         argv_push_verbosity(&cp.args);
 619
 620         return run_command(&cp);
 621 }
 622
 623 /**
 624  * Runs git-merge, returning its exit status.
 625  */
 626 static int run_merge(void)
 627 {
 628         int ret;
 629         struct argv_array args = ARGV_ARRAY_INIT;
 630
 631         argv_array_pushl(&args, "merge", NULL);
 632
 633         /* Shared options */
 634         argv_push_verbosity(&args);
 635         if (opt_progress)
 636                 argv_array_push(&args, opt_progress);
 637
 638         /* Options passed to git-merge */
 639         if (opt_diffstat)
 640                 argv_array_push(&args, opt_diffstat);
 641         if (opt_log)
 642                 argv_array_push(&args, opt_log);
 643         if (opt_signoff)
 644                 argv_array_push(&args, opt_signoff);
 645         if (opt_squash)
 646                 argv_array_push(&args, opt_squash);
 647         if (opt_commit)
 648                 argv_array_push(&args, opt_commit);
 649         if (opt_edit)
 650                 argv_array_push(&args, opt_edit);
 651         if (cleanup_arg)
 652                 argv_array_pushf(&args, "--cleanup=%s", cleanup_arg);
 653         if (opt_ff)
 654                 argv_array_push(&args, opt_ff);
 655         if (opt_verify_signatures)
 656                 argv_array_push(&args, opt_verify_signatures);
 657         argv_array_pushv(&args, opt_strategies.argv);
 658         argv_array_pushv(&args, opt_strategy_opts.argv);
 659         if (opt_gpg_sign)
 660                 argv_array_push(&args, opt_gpg_sign);
 661         if (opt_allow_unrelated_histories > 0)
 662                 argv_array_push(&args, "--allow-unrelated-histories");
 663
 664         argv_array_push(&args, "FETCH_HEAD");
 665         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 666         argv_array_clear(&args);
 667         return ret;
 668 }
 669
 670 /**
 671  * Returns remote's upstream branch for the current branch. If remote is NULL,
 672  * the current branch's configured default remote is used. Returns NULL if
 673  * `remote` does not name a valid remote, HEAD does not point to a branch,
 674  * remote is not the branch's configured remote or the branch does not have any
 675  * configured upstream branch.
 676  */
 677 static const char *get_upstream_branch(const char *remote)
 678 {
 679         struct remote *rm;
 680         struct branch *curr_branch;
 681         const char *curr_branch_remote;
 682
 683         rm = remote_get(remote);
 684         if (!rm)
 685                 return NULL;
 686
 687         curr_branch = branch_get("HEAD");
 688         if (!curr_branch)
 689                 return NULL;
 690
 691         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 692         assert(curr_branch_remote);
 693
 694         if (strcmp(curr_branch_remote, rm->name))
 695                 return NULL;
 696
 697         return branch_get_upstream(curr_branch, NULL);
 698 }
 699
 700 /**
 701  * Derives the remote-tracking branch from the remote and refspec.
 702  *
 703  * FIXME: The current implementation assumes the default mapping of
 704  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 705  */
 706 static const char *get_tracking_branch(const char *remote, const char *refspec)
 707 {
 708         struct refspec_item spec;
 709         const char *spec_src;
 710         const char *merge_branch;
 711
 712         refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);
 713         spec_src = spec.src;
 714         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 715                 spec_src = "HEAD";
 716         else if (skip_prefix(spec_src, "heads/", &spec_src))
 717                 ;
 718         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 719                 ;
 720         else if (starts_with(spec_src, "refs/") ||
 721                 starts_with(spec_src, "tags/") ||
 722                 starts_with(spec_src, "remotes/"))
 723                 spec_src = "";
 724
 725         if (*spec_src) {
 726                 if (!strcmp(remote, "."))
 727                         merge_branch = mkpath("refs/heads/%s", spec_src);
 728                 else
 729                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 730         } else
 731                 merge_branch = NULL;
 732
 733         refspec_item_clear(&spec);
 734         return merge_branch;
 735 }
 736
 737 /**
 738  * Given the repo and refspecs, sets fork_point to the point at which the
 739  * current branch forked from its remote-tracking branch. Returns 0 on success,
 740  * -1 on failure.
 741  */
 742 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 743                 const char *refspec)
 744 {
 745         int ret;
 746         struct branch *curr_branch;
 747         const char *remote_branch;
 748         struct child_process cp = CHILD_PROCESS_INIT;
 749         struct strbuf sb = STRBUF_INIT;
 750
 751         curr_branch = branch_get("HEAD");
 752         if (!curr_branch)
 753                 return -1;
 754
 755         if (refspec)
 756                 remote_branch = get_tracking_branch(repo, refspec);
 757         else
 758                 remote_branch = get_upstream_branch(repo);
 759
 760         if (!remote_branch)
 761                 return -1;
 762
 763         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 764                         remote_branch, curr_branch->name, NULL);
 765         cp.no_stdin = 1;
 766         cp.no_stderr = 1;
 767         cp.git_cmd = 1;
 768
 769         ret = capture_command(&cp, &sb, GIT_MAX_HEXSZ);
 770         if (ret)
 771                 goto cleanup;
 772
 773         ret = get_oid_hex(sb.buf, fork_point);
 774         if (ret)
 775                 goto cleanup;
 776
 777 cleanup:
 778         strbuf_release(&sb);
 779         return ret ? -1 : 0;
 780 }
 781
 782 /**
 783  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 784  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 785  */
 786 static int get_octopus_merge_base(struct object_id *merge_base,
 787                 const struct object_id *curr_head,
 788                 const struct object_id *merge_head,
 789                 const struct object_id *fork_point)
 790 {
 791         struct commit_list *revs = NULL, *result;
 792
 793         commit_list_insert(lookup_commit_reference(the_repository, curr_head),
 794                            &revs);
 795         commit_list_insert(lookup_commit_reference(the_repository, merge_head),
 796                            &revs);
 797         if (!is_null_oid(fork_point))
 798                 commit_list_insert(lookup_commit_reference(the_repository, fork_point),
 799                                    &revs);
 800
 801         result = get_octopus_merge_bases(revs);
 802         free_commit_list(revs);
 803         reduce_heads_replace(&result);
 804
 805         if (!result)
 806                 return 1;
 807
 808         oidcpy(merge_base, &result->item->object.oid);
 809         free_commit_list(result);
 810         return 0;
 811 }
 812
 813 /**
 814  * Given the current HEAD oid, the merge head returned from git-fetch and the
 815  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 816  * appropriate arguments and returns its exit status.
 817  */
 818 static int run_rebase(const struct object_id *curr_head,
 819                 const struct object_id *merge_head,
 820                 const struct object_id *fork_point)
 821 {
 822         int ret;
 823         struct object_id oct_merge_base;
 824         struct argv_array args = ARGV_ARRAY_INIT;
 825
 826         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 827                 if (!is_null_oid(fork_point) && oideq(&oct_merge_base, fork_point))
 828                         fork_point = NULL;
 829
 830         argv_array_push(&args, "rebase");
 831
 832         /* Shared options */
 833         argv_push_verbosity(&args);
 834
 835         /* Options passed to git-rebase */
 836         if (opt_rebase == REBASE_MERGES)
 837                 argv_array_push(&args, "--rebase-merges");
 838         else if (opt_rebase == REBASE_PRESERVE)
 839                 argv_array_push(&args, "--preserve-merges");
 840         else if (opt_rebase == REBASE_INTERACTIVE)
 841                 argv_array_push(&args, "--interactive");
 842         if (opt_diffstat)
 843                 argv_array_push(&args, opt_diffstat);
 844         argv_array_pushv(&args, opt_strategies.argv);
 845         argv_array_pushv(&args, opt_strategy_opts.argv);
 846         if (opt_gpg_sign)
 847                 argv_array_push(&args, opt_gpg_sign);
 848         if (opt_autostash == 0)
 849                 argv_array_push(&args, "--no-autostash");
 850         else if (opt_autostash == 1)
 851                 argv_array_push(&args, "--autostash");
 852         if (opt_verify_signatures &&
 853             !strcmp(opt_verify_signatures, "--verify-signatures"))
 854                 warning(_("ignoring --verify-signatures for rebase"));
 855
 856         argv_array_push(&args, "--onto");
 857         argv_array_push(&args, oid_to_hex(merge_head));
 858
 859         if (fork_point && !is_null_oid(fork_point))
 860                 argv_array_push(&args, oid_to_hex(fork_point));
 861         else
 862                 argv_array_push(&args, oid_to_hex(merge_head));
 863
 864         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 865         argv_array_clear(&args);
 866         return ret;
 867 }
 868
 869 int cmd_pull(int argc, const char **argv, const char *prefix)
 870 {
 871         const char *repo, **refspecs;
 872         struct oid_array merge_heads = OID_ARRAY_INIT;
 873         struct object_id orig_head, curr_head;
 874         struct object_id rebase_fork_point;
 875         int autostash;
 876
 877         if (!getenv("GIT_REFLOG_ACTION"))
 878                 set_reflog_message(argc, argv);
 879
 880         git_config(git_pull_config, NULL);
 881
 882         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 883
 884         if (cleanup_arg)
 885                 /*
 886                  * this only checks the validity of cleanup_arg; we don't need
 887                  * a valid value for use_editor
 888                  */
 889                 get_cleanup_mode(cleanup_arg, 0);
 890
 891         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 892
 893         if (!opt_ff)
 894                 opt_ff = xstrdup_or_null(config_get_ff());
 895
 896         if (opt_rebase < 0)
 897                 opt_rebase = config_get_rebase();
 898
 899         if (read_cache_unmerged())
 900                 die_resolve_conflict("pull");
 901
 902         if (file_exists(git_path_merge_head(the_repository)))
 903                 die_conclude_merge();
 904
 905         if (get_oid("HEAD", &orig_head))
 906                 oidclr(&orig_head);
 907
 908         if (!opt_rebase && opt_autostash != -1)
 909                 die(_("--[no-]autostash option is only valid with --rebase."));
 910
 911         autostash = config_autostash;
 912         if (opt_rebase) {
 913                 if (opt_autostash != -1)
 914                         autostash = opt_autostash;
 915
 916                 if (is_null_oid(&orig_head) && !is_cache_unborn())
 917                         die(_("Updating an unborn branch with changes added to the index."));
 918
 919                 if (!autostash)
 920                         require_clean_work_tree(the_repository,
 921                                 N_("pull with rebase"),
 922                                 _("please commit or stash them."), 1, 0);
 923
 924                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
 925                         oidclr(&rebase_fork_point);
 926         }
 927
 928         if (run_fetch(repo, refspecs))
 929                 return 1;
 930
 931         if (opt_dry_run)
 932                 return 0;
 933
 934         if (get_oid("HEAD", &curr_head))
 935                 oidclr(&curr_head);
 936
 937         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
 938                         !oideq(&orig_head, &curr_head)) {
 939                 /*
 940                  * The fetch involved updating the current branch.
 941                  *
 942                  * The working tree and the index file are still based on
 943                  * orig_head commit, but we are merging into curr_head.
 944                  * Update the working tree to match curr_head.
 945                  */
 946
 947                 warning(_("fetch updated the current branch head.\n"
 948                         "fast-forwarding your working tree from\n"
 949                         "commit %s."), oid_to_hex(&orig_head));
 950
 951                 if (checkout_fast_forward(the_repository, &orig_head,
 952                                           &curr_head, 0))
 953                         die(_("Cannot fast-forward your working tree.\n"
 954                                 "After making sure that you saved anything precious from\n"
 955                                 "$ git diff %s\n"
 956                                 "output, run\n"
 957                                 "$ git reset --hard\n"
 958                                 "to recover."), oid_to_hex(&orig_head));
 959         }
 960
 961         get_merge_heads(&merge_heads);
 962
 963         if (!merge_heads.nr)
 964                 die_no_merge_candidates(repo, refspecs);
 965
 966         if (is_null_oid(&orig_head)) {
 967                 if (merge_heads.nr > 1)
 968                         die(_("Cannot merge multiple branches into empty head."));
 969                 return pull_into_void(merge_heads.oid, &curr_head);
 970         }
 971         if (opt_rebase && merge_heads.nr > 1)
 972                 die(_("Cannot rebase onto multiple branches."));
 973
 974         if (opt_rebase) {
 975                 int ret = 0;
 976                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
 977                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
 978                     submodule_touches_in_range(the_repository, &rebase_fork_point, &curr_head))
 979                         die(_("cannot rebase with locally recorded submodule modifications"));
 980                 if (!autostash) {
 981                         struct commit_list *list = NULL;
 982                         struct commit *merge_head, *head;
 983
 984                         head = lookup_commit_reference(the_repository,
 985                                                        &orig_head);
 986                         commit_list_insert(head, &list);
 987                         merge_head = lookup_commit_reference(the_repository,
 988                                                              &merge_heads.oid[0]);
 989                         if (is_descendant_of(merge_head, list)) {
 990                                 /* we can fast-forward this without invoking rebase */
 991                                 opt_ff = "--ff-only";
 992                                 ret = run_merge();
 993                         }
 994                 }
 995                 ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
 996
 997                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
 998                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
 999                         ret = rebase_submodules();
1000
1001                 return ret;
1002         } else {
1003                 int ret = run_merge();
1004                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1005                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1006                         ret = update_submodules();
1007                 return ret;
1008         }
1009 }