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 "config.h"
  10 #include "builtin.h"
  11 #include "parse-options.h"
  12 #include "exec_cmd.h"
  13 #include "run-command.h"
  14 #include "sha1-array.h"
  15 #include "remote.h"
  16 #include "dir.h"
  17 #include "refs.h"
  18 #include "revision.h"
  19 #include "submodule.h"
  20 #include "submodule-config.h"
  21 #include "tempfile.h"
  22 #include "lockfile.h"
  23 #include "wt-status.h"
  24
  25 enum rebase_type {
  26         REBASE_INVALID = -1,
  27         REBASE_FALSE = 0,
  28         REBASE_TRUE,
  29         REBASE_PRESERVE,
  30         REBASE_INTERACTIVE
  31 };
  32
  33 /**
  34  * Parses the value of --rebase. If value is a false value, returns
  35  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  36  * "preserve", returns REBASE_PRESERVE. If value is a invalid value, dies with
  37  * a fatal error if fatal is true, otherwise returns REBASE_INVALID.
  38  */
  39 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  40                 int fatal)
  41 {
  42         int v = git_parse_maybe_bool(value);
  43
  44         if (!v)
  45                 return REBASE_FALSE;
  46         else if (v > 0)
  47                 return REBASE_TRUE;
  48         else if (!strcmp(value, "preserve"))
  49                 return REBASE_PRESERVE;
  50         else if (!strcmp(value, "interactive"))
  51                 return REBASE_INTERACTIVE;
  52
  53         if (fatal)
  54                 die(_("Invalid value for %s: %s"), key, value);
  55         else
  56                 error(_("Invalid value for %s: %s"), key, value);
  57
  58         return REBASE_INVALID;
  59 }
  60
  61 /**
  62  * Callback for --rebase, which parses arg with parse_config_rebase().
  63  */
  64 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  65 {
  66         enum rebase_type *value = opt->value;
  67
  68         if (arg)
  69                 *value = parse_config_rebase("--rebase", arg, 0);
  70         else
  71                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  72         return *value == REBASE_INVALID ? -1 : 0;
  73 }
  74
  75 static const char * const pull_usage[] = {
  76         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  77         NULL
  78 };
  79
  80 /* Shared options */
  81 static int opt_verbosity;
  82 static char *opt_progress;
  83 static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
  84
  85 /* Options passed to git-merge or git-rebase */
  86 static enum rebase_type opt_rebase = -1;
  87 static char *opt_diffstat;
  88 static char *opt_log;
  89 static char *opt_signoff;
  90 static char *opt_squash;
  91 static char *opt_commit;
  92 static char *opt_edit;
  93 static char *opt_ff;
  94 static char *opt_verify_signatures;
  95 static int opt_autostash = -1;
  96 static int config_autostash;
  97 static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
  98 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
  99 static char *opt_gpg_sign;
 100 static int opt_allow_unrelated_histories;
 101
 102 /* Options passed to git-fetch */
 103 static char *opt_all;
 104 static char *opt_append;
 105 static char *opt_upload_pack;
 106 static int opt_force;
 107 static char *opt_tags;
 108 static char *opt_prune;
 109 static char *max_children;
 110 static int opt_dry_run;
 111 static char *opt_keep;
 112 static char *opt_depth;
 113 static char *opt_unshallow;
 114 static char *opt_update_shallow;
 115 static char *opt_refmap;
 116
 117 static struct option pull_options[] = {
 118         /* Shared options */
 119         OPT__VERBOSITY(&opt_verbosity),
 120         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 121                 N_("force progress reporting"),
 122                 PARSE_OPT_NOARG),
 123         { OPTION_CALLBACK, 0, "recurse-submodules",
 124                    &recurse_submodules, N_("on-demand"),
 125                    N_("control for recursive fetching of submodules"),
 126                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules },
 127
 128         /* Options passed to git-merge or git-rebase */
 129         OPT_GROUP(N_("Options related to merging")),
 130         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 131           "false|true|preserve|interactive",
 132           N_("incorporate changes by rebasing rather than merging"),
 133           PARSE_OPT_OPTARG, parse_opt_rebase },
 134         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 135                 N_("do not show a diffstat at the end of the merge"),
 136                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 137         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 138                 N_("show a diffstat at the end of the merge"),
 139                 PARSE_OPT_NOARG),
 140         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 141                 N_("(synonym to --stat)"),
 142                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 143         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 144                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 145                 PARSE_OPT_OPTARG),
 146         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 147                 N_("add Signed-off-by:"),
 148                 PARSE_OPT_OPTARG),
 149         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 150                 N_("create a single commit instead of doing a merge"),
 151                 PARSE_OPT_NOARG),
 152         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 153                 N_("perform a commit if the merge succeeds (default)"),
 154                 PARSE_OPT_NOARG),
 155         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 156                 N_("edit message before committing"),
 157                 PARSE_OPT_NOARG),
 158         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 159                 N_("allow fast-forward"),
 160                 PARSE_OPT_NOARG),
 161         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 162                 N_("abort if fast-forward is not possible"),
 163                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 164         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 165                 N_("verify that the named commit has a valid GPG signature"),
 166                 PARSE_OPT_NOARG),
 167         OPT_BOOL(0, "autostash", &opt_autostash,
 168                 N_("automatically stash/stash pop before and after rebase")),
 169         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 170                 N_("merge strategy to use"),
 171                 0),
 172         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 173                 N_("option=value"),
 174                 N_("option for selected merge strategy"),
 175                 0),
 176         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 177                 N_("GPG sign commit"),
 178                 PARSE_OPT_OPTARG),
 179         OPT_SET_INT(0, "allow-unrelated-histories",
 180                     &opt_allow_unrelated_histories,
 181                     N_("allow merging unrelated histories"), 1),
 182
 183         /* Options passed to git-fetch */
 184         OPT_GROUP(N_("Options related to fetching")),
 185         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 186                 N_("fetch from all remotes"),
 187                 PARSE_OPT_NOARG),
 188         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 189                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 190                 PARSE_OPT_NOARG),
 191         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 192                 N_("path to upload pack on remote end"),
 193                 0),
 194         OPT__FORCE(&opt_force, N_("force overwrite of local branch")),
 195         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 196                 N_("fetch all tags and associated objects"),
 197                 PARSE_OPT_NOARG),
 198         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 199                 N_("prune remote-tracking branches no longer on remote"),
 200                 PARSE_OPT_NOARG),
 201         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 202                 N_("number of submodules pulled in parallel"),
 203                 PARSE_OPT_OPTARG),
 204         OPT_BOOL(0, "dry-run", &opt_dry_run,
 205                 N_("dry run")),
 206         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 207                 N_("keep downloaded pack"),
 208                 PARSE_OPT_NOARG),
 209         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 210                 N_("deepen history of shallow clone"),
 211                 0),
 212         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 213                 N_("convert to a complete repository"),
 214                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 215         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 216                 N_("accept refs that update .git/shallow"),
 217                 PARSE_OPT_NOARG),
 218         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 219                 N_("specify fetch refmap"),
 220                 PARSE_OPT_NONEG),
 221
 222         OPT_END()
 223 };
 224
 225 /**
 226  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 227  */
 228 static void argv_push_verbosity(struct argv_array *arr)
 229 {
 230         int verbosity;
 231
 232         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 233                 argv_array_push(arr, "-v");
 234
 235         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 236                 argv_array_push(arr, "-q");
 237 }
 238
 239 /**
 240  * Pushes "-f" switches into arr to match the opt_force level.
 241  */
 242 static void argv_push_force(struct argv_array *arr)
 243 {
 244         int force = opt_force;
 245         while (force-- > 0)
 246                 argv_array_push(arr, "-f");
 247 }
 248
 249 /**
 250  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 251  */
 252 static void set_reflog_message(int argc, const char **argv)
 253 {
 254         int i;
 255         struct strbuf msg = STRBUF_INIT;
 256
 257         for (i = 0; i < argc; i++) {
 258                 if (i)
 259                         strbuf_addch(&msg, ' ');
 260                 strbuf_addstr(&msg, argv[i]);
 261         }
 262
 263         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 264
 265         strbuf_release(&msg);
 266 }
 267
 268 /**
 269  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 270  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 271  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 272  * error.
 273  */
 274 static const char *config_get_ff(void)
 275 {
 276         const char *value;
 277
 278         if (git_config_get_value("pull.ff", &value))
 279                 return NULL;
 280
 281         switch (git_parse_maybe_bool(value)) {
 282         case 0:
 283                 return "--no-ff";
 284         case 1:
 285                 return "--ff";
 286         }
 287
 288         if (!strcmp(value, "only"))
 289                 return "--ff-only";
 290
 291         die(_("Invalid value for pull.ff: %s"), value);
 292 }
 293
 294 /**
 295  * Returns the default configured value for --rebase. It first looks for the
 296  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 297  * branch, and if HEAD is detached or the configuration key does not exist,
 298  * looks for the value of "pull.rebase". If both configuration keys do not
 299  * exist, returns REBASE_FALSE.
 300  */
 301 static enum rebase_type config_get_rebase(void)
 302 {
 303         struct branch *curr_branch = branch_get("HEAD");
 304         const char *value;
 305
 306         if (curr_branch) {
 307                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 308
 309                 if (!git_config_get_value(key, &value)) {
 310                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 311                         free(key);
 312                         return ret;
 313                 }
 314
 315                 free(key);
 316         }
 317
 318         if (!git_config_get_value("pull.rebase", &value))
 319                 return parse_config_rebase("pull.rebase", value, 1);
 320
 321         return REBASE_FALSE;
 322 }
 323
 324 /**
 325  * Read config variables.
 326  */
 327 static int git_pull_config(const char *var, const char *value, void *cb)
 328 {
 329         if (!strcmp(var, "rebase.autostash")) {
 330                 config_autostash = git_config_bool(var, value);
 331                 return 0;
 332         } else if (!strcmp(var, "submodule.recurse")) {
 333                 recurse_submodules = git_config_bool(var, value) ?
 334                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 335                 return 0;
 336         }
 337         return git_default_config(var, value, cb);
 338 }
 339
 340 /**
 341  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 342  * into merge_heads.
 343  */
 344 static void get_merge_heads(struct oid_array *merge_heads)
 345 {
 346         const char *filename = git_path_fetch_head();
 347         FILE *fp;
 348         struct strbuf sb = STRBUF_INIT;
 349         struct object_id oid;
 350
 351         fp = xfopen(filename, "r");
 352         while (strbuf_getline_lf(&sb, fp) != EOF) {
 353                 if (get_oid_hex(sb.buf, &oid))
 354                         continue;  /* invalid line: does not start with SHA1 */
 355                 if (starts_with(sb.buf + GIT_SHA1_HEXSZ, "\tnot-for-merge\t"))
 356                         continue;  /* ref is not-for-merge */
 357                 oid_array_append(merge_heads, &oid);
 358         }
 359         fclose(fp);
 360         strbuf_release(&sb);
 361 }
 362
 363 /**
 364  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 365  * retrieve the name of the remote if the repository only has one remote.
 366  */
 367 static int get_only_remote(struct remote *remote, void *cb_data)
 368 {
 369         const char **remote_name = cb_data;
 370
 371         if (*remote_name)
 372                 return -1;
 373
 374         *remote_name = remote->name;
 375         return 0;
 376 }
 377
 378 /**
 379  * Dies with the appropriate reason for why there are no merge candidates:
 380  *
 381  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 382  *    up not fetching anything. This is usually because the user provided a
 383  *    wildcard refspec which had no matches on the remote end.
 384  *
 385  * 2. We fetched from a non-default remote, but didn't specify a branch to
 386  *    merge. We can't use the configured one because it applies to the default
 387  *    remote, thus the user must specify the branches to merge.
 388  *
 389  * 3. We fetched from the branch's or repo's default remote, but:
 390  *
 391  *    a. We are not on a branch, so there will never be a configured branch to
 392  *       merge with.
 393  *
 394  *    b. We are on a branch, but there is no configured branch to merge with.
 395  *
 396  * 4. We fetched from the branch's or repo's default remote, but the configured
 397  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 398  *    part of the configured fetch refspec.)
 399  */
 400 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 401 {
 402         struct branch *curr_branch = branch_get("HEAD");
 403         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 404
 405         if (*refspecs) {
 406                 if (opt_rebase)
 407                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 408                 else
 409                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 410                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 411                                         "matches on the remote end."));
 412         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 413                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 414                         "a branch. Because this is not the default configured remote\n"
 415                         "for your current branch, you must specify a branch on the command line."),
 416                         repo);
 417         } else if (!curr_branch) {
 418                 fprintf_ln(stderr, _("You are not currently on a branch."));
 419                 if (opt_rebase)
 420                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 421                 else
 422                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 423                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 424                 fprintf(stderr, "\n");
 425                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 426                 fprintf(stderr, "\n");
 427         } else if (!curr_branch->merge_nr) {
 428                 const char *remote_name = NULL;
 429
 430                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 431                         remote_name = _("<remote>");
 432
 433                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 434                 if (opt_rebase)
 435                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 436                 else
 437                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 438                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 439                 fprintf(stderr, "\n");
 440                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 441                 fprintf(stderr, "\n");
 442                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 443                 fprintf(stderr, "\n");
 444                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 445                                 remote_name, _("<branch>"), curr_branch->name);
 446         } else
 447                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 448                         "from the remote, but no such ref was fetched."),
 449                         *curr_branch->merge_name);
 450         exit(1);
 451 }
 452
 453 /**
 454  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 455  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 456  * is not provided in argv, it is set to NULL.
 457  */
 458 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 459                 const char ***refspecs)
 460 {
 461         if (argc > 0) {
 462                 *repo = *argv++;
 463                 argc--;
 464         } else
 465                 *repo = NULL;
 466         *refspecs = argv;
 467 }
 468
 469 /**
 470  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 471  * repository and refspecs to fetch, or NULL if they are not provided.
 472  */
 473 static int run_fetch(const char *repo, const char **refspecs)
 474 {
 475         struct argv_array args = ARGV_ARRAY_INIT;
 476         int ret;
 477
 478         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 479
 480         /* Shared options */
 481         argv_push_verbosity(&args);
 482         if (opt_progress)
 483                 argv_array_push(&args, opt_progress);
 484
 485         /* Options passed to git-fetch */
 486         if (opt_all)
 487                 argv_array_push(&args, opt_all);
 488         if (opt_append)
 489                 argv_array_push(&args, opt_append);
 490         if (opt_upload_pack)
 491                 argv_array_push(&args, opt_upload_pack);
 492         argv_push_force(&args);
 493         if (opt_tags)
 494                 argv_array_push(&args, opt_tags);
 495         if (opt_prune)
 496                 argv_array_push(&args, opt_prune);
 497         if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
 498                 switch (recurse_submodules) {
 499                 case RECURSE_SUBMODULES_ON:
 500                         argv_array_push(&args, "--recurse-submodules=on");
 501                         break;
 502                 case RECURSE_SUBMODULES_OFF:
 503                         argv_array_push(&args, "--recurse-submodules=no");
 504                         break;
 505                 case RECURSE_SUBMODULES_ON_DEMAND:
 506                         argv_array_push(&args, "--recurse-submodules=on-demand");
 507                         break;
 508                 default:
 509                         BUG("submodule recursion option not understood");
 510                 }
 511         if (max_children)
 512                 argv_array_push(&args, max_children);
 513         if (opt_dry_run)
 514                 argv_array_push(&args, "--dry-run");
 515         if (opt_keep)
 516                 argv_array_push(&args, opt_keep);
 517         if (opt_depth)
 518                 argv_array_push(&args, opt_depth);
 519         if (opt_unshallow)
 520                 argv_array_push(&args, opt_unshallow);
 521         if (opt_update_shallow)
 522                 argv_array_push(&args, opt_update_shallow);
 523         if (opt_refmap)
 524                 argv_array_push(&args, opt_refmap);
 525
 526         if (repo) {
 527                 argv_array_push(&args, repo);
 528                 argv_array_pushv(&args, refspecs);
 529         } else if (*refspecs)
 530                 die("BUG: refspecs without repo?");
 531         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 532         argv_array_clear(&args);
 533         return ret;
 534 }
 535
 536 /**
 537  * "Pulls into void" by branching off merge_head.
 538  */
 539 static int pull_into_void(const struct object_id *merge_head,
 540                 const struct object_id *curr_head)
 541 {
 542         /*
 543          * Two-way merge: we treat the index as based on an empty tree,
 544          * and try to fast-forward to HEAD. This ensures we will not lose
 545          * index/worktree changes that the user already made on the unborn
 546          * branch.
 547          */
 548         if (checkout_fast_forward(&empty_tree_oid, merge_head, 0))
 549                 return 1;
 550
 551         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 552                 return 1;
 553
 554         return 0;
 555 }
 556
 557 static int rebase_submodules(void)
 558 {
 559         struct child_process cp = CHILD_PROCESS_INIT;
 560
 561         cp.git_cmd = 1;
 562         cp.no_stdin = 1;
 563         argv_array_pushl(&cp.args, "submodule", "update",
 564                                    "--recursive", "--rebase", NULL);
 565
 566         return run_command(&cp);
 567 }
 568
 569 static int update_submodules(void)
 570 {
 571         struct child_process cp = CHILD_PROCESS_INIT;
 572
 573         cp.git_cmd = 1;
 574         cp.no_stdin = 1;
 575         argv_array_pushl(&cp.args, "submodule", "update",
 576                                    "--recursive", "--checkout", NULL);
 577
 578         return run_command(&cp);
 579 }
 580
 581 /**
 582  * Runs git-merge, returning its exit status.
 583  */
 584 static int run_merge(void)
 585 {
 586         int ret;
 587         struct argv_array args = ARGV_ARRAY_INIT;
 588
 589         argv_array_pushl(&args, "merge", NULL);
 590
 591         /* Shared options */
 592         argv_push_verbosity(&args);
 593         if (opt_progress)
 594                 argv_array_push(&args, opt_progress);
 595
 596         /* Options passed to git-merge */
 597         if (opt_diffstat)
 598                 argv_array_push(&args, opt_diffstat);
 599         if (opt_log)
 600                 argv_array_push(&args, opt_log);
 601         if (opt_signoff)
 602                 argv_array_push(&args, opt_signoff);
 603         if (opt_squash)
 604                 argv_array_push(&args, opt_squash);
 605         if (opt_commit)
 606                 argv_array_push(&args, opt_commit);
 607         if (opt_edit)
 608                 argv_array_push(&args, opt_edit);
 609         if (opt_ff)
 610                 argv_array_push(&args, opt_ff);
 611         if (opt_verify_signatures)
 612                 argv_array_push(&args, opt_verify_signatures);
 613         argv_array_pushv(&args, opt_strategies.argv);
 614         argv_array_pushv(&args, opt_strategy_opts.argv);
 615         if (opt_gpg_sign)
 616                 argv_array_push(&args, opt_gpg_sign);
 617         if (opt_allow_unrelated_histories > 0)
 618                 argv_array_push(&args, "--allow-unrelated-histories");
 619
 620         argv_array_push(&args, "FETCH_HEAD");
 621         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 622         argv_array_clear(&args);
 623         return ret;
 624 }
 625
 626 /**
 627  * Returns remote's upstream branch for the current branch. If remote is NULL,
 628  * the current branch's configured default remote is used. Returns NULL if
 629  * `remote` does not name a valid remote, HEAD does not point to a branch,
 630  * remote is not the branch's configured remote or the branch does not have any
 631  * configured upstream branch.
 632  */
 633 static const char *get_upstream_branch(const char *remote)
 634 {
 635         struct remote *rm;
 636         struct branch *curr_branch;
 637         const char *curr_branch_remote;
 638
 639         rm = remote_get(remote);
 640         if (!rm)
 641                 return NULL;
 642
 643         curr_branch = branch_get("HEAD");
 644         if (!curr_branch)
 645                 return NULL;
 646
 647         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 648         assert(curr_branch_remote);
 649
 650         if (strcmp(curr_branch_remote, rm->name))
 651                 return NULL;
 652
 653         return branch_get_upstream(curr_branch, NULL);
 654 }
 655
 656 /**
 657  * Derives the remote tracking branch from the remote and refspec.
 658  *
 659  * FIXME: The current implementation assumes the default mapping of
 660  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 661  */
 662 static const char *get_tracking_branch(const char *remote, const char *refspec)
 663 {
 664         struct refspec *spec;
 665         const char *spec_src;
 666         const char *merge_branch;
 667
 668         spec = parse_fetch_refspec(1, &refspec);
 669         spec_src = spec->src;
 670         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 671                 spec_src = "HEAD";
 672         else if (skip_prefix(spec_src, "heads/", &spec_src))
 673                 ;
 674         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 675                 ;
 676         else if (starts_with(spec_src, "refs/") ||
 677                 starts_with(spec_src, "tags/") ||
 678                 starts_with(spec_src, "remotes/"))
 679                 spec_src = "";
 680
 681         if (*spec_src) {
 682                 if (!strcmp(remote, "."))
 683                         merge_branch = mkpath("refs/heads/%s", spec_src);
 684                 else
 685                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 686         } else
 687                 merge_branch = NULL;
 688
 689         free_refspec(1, spec);
 690         return merge_branch;
 691 }
 692
 693 /**
 694  * Given the repo and refspecs, sets fork_point to the point at which the
 695  * current branch forked from its remote tracking branch. Returns 0 on success,
 696  * -1 on failure.
 697  */
 698 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 699                 const char *refspec)
 700 {
 701         int ret;
 702         struct branch *curr_branch;
 703         const char *remote_branch;
 704         struct child_process cp = CHILD_PROCESS_INIT;
 705         struct strbuf sb = STRBUF_INIT;
 706
 707         curr_branch = branch_get("HEAD");
 708         if (!curr_branch)
 709                 return -1;
 710
 711         if (refspec)
 712                 remote_branch = get_tracking_branch(repo, refspec);
 713         else
 714                 remote_branch = get_upstream_branch(repo);
 715
 716         if (!remote_branch)
 717                 return -1;
 718
 719         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 720                         remote_branch, curr_branch->name, NULL);
 721         cp.no_stdin = 1;
 722         cp.no_stderr = 1;
 723         cp.git_cmd = 1;
 724
 725         ret = capture_command(&cp, &sb, GIT_SHA1_HEXSZ);
 726         if (ret)
 727                 goto cleanup;
 728
 729         ret = get_oid_hex(sb.buf, fork_point);
 730         if (ret)
 731                 goto cleanup;
 732
 733 cleanup:
 734         strbuf_release(&sb);
 735         return ret ? -1 : 0;
 736 }
 737
 738 /**
 739  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 740  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 741  */
 742 static int get_octopus_merge_base(struct object_id *merge_base,
 743                 const struct object_id *curr_head,
 744                 const struct object_id *merge_head,
 745                 const struct object_id *fork_point)
 746 {
 747         struct commit_list *revs = NULL, *result;
 748
 749         commit_list_insert(lookup_commit_reference(curr_head), &revs);
 750         commit_list_insert(lookup_commit_reference(merge_head), &revs);
 751         if (!is_null_oid(fork_point))
 752                 commit_list_insert(lookup_commit_reference(fork_point), &revs);
 753
 754         result = get_octopus_merge_bases(revs);
 755         free_commit_list(revs);
 756         reduce_heads_replace(&result);
 757
 758         if (!result)
 759                 return 1;
 760
 761         oidcpy(merge_base, &result->item->object.oid);
 762         free_commit_list(result);
 763         return 0;
 764 }
 765
 766 /**
 767  * Given the current HEAD SHA1, the merge head returned from git-fetch and the
 768  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 769  * appropriate arguments and returns its exit status.
 770  */
 771 static int run_rebase(const struct object_id *curr_head,
 772                 const struct object_id *merge_head,
 773                 const struct object_id *fork_point)
 774 {
 775         int ret;
 776         struct object_id oct_merge_base;
 777         struct argv_array args = ARGV_ARRAY_INIT;
 778
 779         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 780                 if (!is_null_oid(fork_point) && !oidcmp(&oct_merge_base, fork_point))
 781                         fork_point = NULL;
 782
 783         argv_array_push(&args, "rebase");
 784
 785         /* Shared options */
 786         argv_push_verbosity(&args);
 787
 788         /* Options passed to git-rebase */
 789         if (opt_rebase == REBASE_PRESERVE)
 790                 argv_array_push(&args, "--preserve-merges");
 791         else if (opt_rebase == REBASE_INTERACTIVE)
 792                 argv_array_push(&args, "--interactive");
 793         if (opt_diffstat)
 794                 argv_array_push(&args, opt_diffstat);
 795         argv_array_pushv(&args, opt_strategies.argv);
 796         argv_array_pushv(&args, opt_strategy_opts.argv);
 797         if (opt_gpg_sign)
 798                 argv_array_push(&args, opt_gpg_sign);
 799         if (opt_autostash == 0)
 800                 argv_array_push(&args, "--no-autostash");
 801         else if (opt_autostash == 1)
 802                 argv_array_push(&args, "--autostash");
 803         if (opt_verify_signatures &&
 804             !strcmp(opt_verify_signatures, "--verify-signatures"))
 805                 warning(_("ignoring --verify-signatures for rebase"));
 806
 807         argv_array_push(&args, "--onto");
 808         argv_array_push(&args, oid_to_hex(merge_head));
 809
 810         if (fork_point && !is_null_oid(fork_point))
 811                 argv_array_push(&args, oid_to_hex(fork_point));
 812         else
 813                 argv_array_push(&args, oid_to_hex(merge_head));
 814
 815         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 816         argv_array_clear(&args);
 817         return ret;
 818 }
 819
 820 int cmd_pull(int argc, const char **argv, const char *prefix)
 821 {
 822         const char *repo, **refspecs;
 823         struct oid_array merge_heads = OID_ARRAY_INIT;
 824         struct object_id orig_head, curr_head;
 825         struct object_id rebase_fork_point;
 826         int autostash;
 827
 828         if (!getenv("GIT_REFLOG_ACTION"))
 829                 set_reflog_message(argc, argv);
 830
 831         git_config(git_pull_config, NULL);
 832
 833         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 834
 835         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 836
 837         if (!opt_ff)
 838                 opt_ff = xstrdup_or_null(config_get_ff());
 839
 840         if (opt_rebase < 0)
 841                 opt_rebase = config_get_rebase();
 842
 843         if (read_cache_unmerged())
 844                 die_resolve_conflict("pull");
 845
 846         if (file_exists(git_path_merge_head()))
 847                 die_conclude_merge();
 848
 849         if (get_oid("HEAD", &orig_head))
 850                 oidclr(&orig_head);
 851
 852         if (!opt_rebase && opt_autostash != -1)
 853                 die(_("--[no-]autostash option is only valid with --rebase."));
 854
 855         autostash = config_autostash;
 856         if (opt_rebase) {
 857                 if (opt_autostash != -1)
 858                         autostash = opt_autostash;
 859
 860                 if (is_null_oid(&orig_head) && !is_cache_unborn())
 861                         die(_("Updating an unborn branch with changes added to the index."));
 862
 863                 if (!autostash)
 864                         require_clean_work_tree(N_("pull with rebase"),
 865                                 _("please commit or stash them."), 1, 0);
 866
 867                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
 868                         oidclr(&rebase_fork_point);
 869         }
 870
 871         if (run_fetch(repo, refspecs))
 872                 return 1;
 873
 874         if (opt_dry_run)
 875                 return 0;
 876
 877         if (get_oid("HEAD", &curr_head))
 878                 oidclr(&curr_head);
 879
 880         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
 881                         oidcmp(&orig_head, &curr_head)) {
 882                 /*
 883                  * The fetch involved updating the current branch.
 884                  *
 885                  * The working tree and the index file are still based on
 886                  * orig_head commit, but we are merging into curr_head.
 887                  * Update the working tree to match curr_head.
 888                  */
 889
 890                 warning(_("fetch updated the current branch head.\n"
 891                         "fast-forwarding your working tree from\n"
 892                         "commit %s."), oid_to_hex(&orig_head));
 893
 894                 if (checkout_fast_forward(&orig_head, &curr_head, 0))
 895                         die(_("Cannot fast-forward your working tree.\n"
 896                                 "After making sure that you saved anything precious from\n"
 897                                 "$ git diff %s\n"
 898                                 "output, run\n"
 899                                 "$ git reset --hard\n"
 900                                 "to recover."), oid_to_hex(&orig_head));
 901         }
 902
 903         get_merge_heads(&merge_heads);
 904
 905         if (!merge_heads.nr)
 906                 die_no_merge_candidates(repo, refspecs);
 907
 908         if (is_null_oid(&orig_head)) {
 909                 if (merge_heads.nr > 1)
 910                         die(_("Cannot merge multiple branches into empty head."));
 911                 return pull_into_void(merge_heads.oid, &curr_head);
 912         }
 913         if (opt_rebase && merge_heads.nr > 1)
 914                 die(_("Cannot rebase onto multiple branches."));
 915
 916         if (opt_rebase) {
 917                 int ret = 0;
 918                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
 919                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
 920                     submodule_touches_in_range(&rebase_fork_point, &curr_head))
 921                         die(_("cannot rebase with locally recorded submodule modifications"));
 922                 if (!autostash) {
 923                         struct commit_list *list = NULL;
 924                         struct commit *merge_head, *head;
 925
 926                         head = lookup_commit_reference(&orig_head);
 927                         commit_list_insert(head, &list);
 928                         merge_head = lookup_commit_reference(&merge_heads.oid[0]);
 929                         if (is_descendant_of(merge_head, list)) {
 930                                 /* we can fast-forward this without invoking rebase */
 931                                 opt_ff = "--ff-only";
 932                                 ret = run_merge();
 933                         }
 934                 }
 935                 ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
 936
 937                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
 938                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
 939                         ret = rebase_submodules();
 940
 941                 return ret;
 942         } else {
 943                 int ret = run_merge();
 944                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
 945                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
 946                         ret = update_submodules();
 947                 return ret;
 948         }
 949 }