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 "oid-array.h"
  16 #include "remote.h"
  17 #include "dir.h"
  18 #include "rebase.h"
  19 #include "refs.h"
  20 #include "refspec.h"
  21 #include "revision.h"
  22 #include "submodule.h"
  23 #include "submodule-config.h"
  24 #include "tempfile.h"
  25 #include "lockfile.h"
  26 #include "wt-status.h"
  27 #include "commit-reach.h"
  28 #include "sequencer.h"
  29
  30 /**
  31  * Parses the value of --rebase. If value is a false value, returns
  32  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  33  * "merges", returns REBASE_MERGES. If value is "preserve", returns
  34  * REBASE_PRESERVE. If value is a invalid value, dies with a fatal error if
  35  * fatal is true, otherwise returns REBASE_INVALID.
  36  */
  37 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  38                 int fatal)
  39 {
  40         enum rebase_type v = rebase_parse_value(value);
  41         if (v != REBASE_INVALID)
  42                 return v;
  43
  44         if (fatal)
  45                 die(_("Invalid value for %s: %s"), key, value);
  46         else
  47                 error(_("Invalid value for %s: %s"), key, value);
  48
  49         return REBASE_INVALID;
  50 }
  51
  52 /**
  53  * Callback for --rebase, which parses arg with parse_config_rebase().
  54  */
  55 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  56 {
  57         enum rebase_type *value = opt->value;
  58
  59         if (arg)
  60                 *value = parse_config_rebase("--rebase", arg, 0);
  61         else
  62                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  63         return *value == REBASE_INVALID ? -1 : 0;
  64 }
  65
  66 static const char * const pull_usage[] = {
  67         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  68         NULL
  69 };
  70
  71 /* Shared options */
  72 static int opt_verbosity;
  73 static char *opt_progress;
  74 static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
  75
  76 /* Options passed to git-merge or git-rebase */
  77 static enum rebase_type opt_rebase = -1;
  78 static char *opt_diffstat;
  79 static char *opt_log;
  80 static char *opt_signoff;
  81 static char *opt_squash;
  82 static char *opt_commit;
  83 static char *opt_edit;
  84 static char *cleanup_arg;
  85 static char *opt_ff;
  86 static char *opt_verify_signatures;
  87 static int opt_autostash = -1;
  88 static int config_autostash;
  89 static int check_trust_level = 1;
  90 static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
  91 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
  92 static char *opt_gpg_sign;
  93 static int opt_allow_unrelated_histories;
  94
  95 /* Options passed to git-fetch */
  96 static char *opt_all;
  97 static char *opt_append;
  98 static char *opt_upload_pack;
  99 static int opt_force;
 100 static char *opt_tags;
 101 static char *opt_prune;
 102 static char *max_children;
 103 static int opt_dry_run;
 104 static char *opt_keep;
 105 static char *opt_depth;
 106 static char *opt_unshallow;
 107 static char *opt_update_shallow;
 108 static char *opt_refmap;
 109 static char *opt_ipv4;
 110 static char *opt_ipv6;
 111 static int opt_show_forced_updates = -1;
 112 static char *set_upstream;
 113
 114 static struct option pull_options[] = {
 115         /* Shared options */
 116         OPT__VERBOSITY(&opt_verbosity),
 117         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 118                 N_("force progress reporting"),
 119                 PARSE_OPT_NOARG),
 120         { OPTION_CALLBACK, 0, "recurse-submodules",
 121                    &recurse_submodules, N_("on-demand"),
 122                    N_("control for recursive fetching of submodules"),
 123                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules },
 124
 125         /* Options passed to git-merge or git-rebase */
 126         OPT_GROUP(N_("Options related to merging")),
 127         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 128           "(false|true|merges|preserve|interactive)",
 129           N_("incorporate changes by rebasing rather than merging"),
 130           PARSE_OPT_OPTARG, parse_opt_rebase },
 131         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 132                 N_("do not show a diffstat at the end of the merge"),
 133                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 134         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 135                 N_("show a diffstat at the end of the merge"),
 136                 PARSE_OPT_NOARG),
 137         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 138                 N_("(synonym to --stat)"),
 139                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 140         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 141                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 142                 PARSE_OPT_OPTARG),
 143         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 144                 N_("add Signed-off-by:"),
 145                 PARSE_OPT_OPTARG),
 146         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 147                 N_("create a single commit instead of doing a merge"),
 148                 PARSE_OPT_NOARG),
 149         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 150                 N_("perform a commit if the merge succeeds (default)"),
 151                 PARSE_OPT_NOARG),
 152         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 153                 N_("edit message before committing"),
 154                 PARSE_OPT_NOARG),
 155         OPT_CLEANUP(&cleanup_arg),
 156         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 157                 N_("allow fast-forward"),
 158                 PARSE_OPT_NOARG),
 159         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 160                 N_("abort if fast-forward is not possible"),
 161                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 162         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 163                 N_("verify that the named commit has a valid GPG signature"),
 164                 PARSE_OPT_NOARG),
 165         OPT_BOOL(0, "autostash", &opt_autostash,
 166                 N_("automatically stash/stash pop before and after rebase")),
 167         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 168                 N_("merge strategy to use"),
 169                 0),
 170         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 171                 N_("option=value"),
 172                 N_("option for selected merge strategy"),
 173                 0),
 174         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 175                 N_("GPG sign commit"),
 176                 PARSE_OPT_OPTARG),
 177         OPT_SET_INT(0, "allow-unrelated-histories",
 178                     &opt_allow_unrelated_histories,
 179                     N_("allow merging unrelated histories"), 1),
 180
 181         /* Options passed to git-fetch */
 182         OPT_GROUP(N_("Options related to fetching")),
 183         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 184                 N_("fetch from all remotes"),
 185                 PARSE_OPT_NOARG),
 186         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 187                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 188                 PARSE_OPT_NOARG),
 189         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 190                 N_("path to upload pack on remote end"),
 191                 0),
 192         OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),
 193         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 194                 N_("fetch all tags and associated objects"),
 195                 PARSE_OPT_NOARG),
 196         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 197                 N_("prune remote-tracking branches no longer on remote"),
 198                 PARSE_OPT_NOARG),
 199         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 200                 N_("number of submodules pulled in parallel"),
 201                 PARSE_OPT_OPTARG),
 202         OPT_BOOL(0, "dry-run", &opt_dry_run,
 203                 N_("dry run")),
 204         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 205                 N_("keep downloaded pack"),
 206                 PARSE_OPT_NOARG),
 207         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 208                 N_("deepen history of shallow clone"),
 209                 0),
 210         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 211                 N_("convert to a complete repository"),
 212                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 213         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 214                 N_("accept refs that update .git/shallow"),
 215                 PARSE_OPT_NOARG),
 216         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 217                 N_("specify fetch refmap"),
 218                 PARSE_OPT_NONEG),
 219         OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,
 220                 N_("use IPv4 addresses only"),
 221                 PARSE_OPT_NOARG),
 222         OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 223                 N_("use IPv6 addresses only"),
 224                 PARSE_OPT_NOARG),
 225         OPT_BOOL(0, "show-forced-updates", &opt_show_forced_updates,
 226                  N_("check for forced-updates on all updated branches")),
 227         OPT_PASSTHRU(0, "set-upstream", &set_upstream, NULL,
 228                 N_("set upstream for git pull/fetch"),
 229                 PARSE_OPT_NOARG),
 230
 231         OPT_END()
 232 };
 233
 234 /**
 235  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 236  */
 237 static void argv_push_verbosity(struct argv_array *arr)
 238 {
 239         int verbosity;
 240
 241         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 242                 argv_array_push(arr, "-v");
 243
 244         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 245                 argv_array_push(arr, "-q");
 246 }
 247
 248 /**
 249  * Pushes "-f" switches into arr to match the opt_force level.
 250  */
 251 static void argv_push_force(struct argv_array *arr)
 252 {
 253         int force = opt_force;
 254         while (force-- > 0)
 255                 argv_array_push(arr, "-f");
 256 }
 257
 258 /**
 259  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 260  */
 261 static void set_reflog_message(int argc, const char **argv)
 262 {
 263         int i;
 264         struct strbuf msg = STRBUF_INIT;
 265
 266         for (i = 0; i < argc; i++) {
 267                 if (i)
 268                         strbuf_addch(&msg, ' ');
 269                 strbuf_addstr(&msg, argv[i]);
 270         }
 271
 272         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 273
 274         strbuf_release(&msg);
 275 }
 276
 277 /**
 278  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 279  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 280  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 281  * error.
 282  */
 283 static const char *config_get_ff(void)
 284 {
 285         const char *value;
 286
 287         if (git_config_get_value("pull.ff", &value))
 288                 return NULL;
 289
 290         switch (git_parse_maybe_bool(value)) {
 291         case 0:
 292                 return "--no-ff";
 293         case 1:
 294                 return "--ff";
 295         }
 296
 297         if (!strcmp(value, "only"))
 298                 return "--ff-only";
 299
 300         die(_("Invalid value for pull.ff: %s"), value);
 301 }
 302
 303 /**
 304  * Returns the default configured value for --rebase. It first looks for the
 305  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 306  * branch, and if HEAD is detached or the configuration key does not exist,
 307  * looks for the value of "pull.rebase". If both configuration keys do not
 308  * exist, returns REBASE_FALSE.
 309  */
 310 static enum rebase_type config_get_rebase(void)
 311 {
 312         struct branch *curr_branch = branch_get("HEAD");
 313         const char *value;
 314
 315         if (curr_branch) {
 316                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 317
 318                 if (!git_config_get_value(key, &value)) {
 319                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 320                         free(key);
 321                         return ret;
 322                 }
 323
 324                 free(key);
 325         }
 326
 327         if (!git_config_get_value("pull.rebase", &value))
 328                 return parse_config_rebase("pull.rebase", value, 1);
 329
 330         return REBASE_FALSE;
 331 }
 332
 333 /**
 334  * Read config variables.
 335  */
 336 static int git_pull_config(const char *var, const char *value, void *cb)
 337 {
 338         int status;
 339
 340         if (!strcmp(var, "rebase.autostash")) {
 341                 config_autostash = git_config_bool(var, value);
 342                 return 0;
 343         } else if (!strcmp(var, "submodule.recurse")) {
 344                 recurse_submodules = git_config_bool(var, value) ?
 345                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 346                 return 0;
 347         } else if (!strcmp(var, "gpg.mintrustlevel")) {
 348                 check_trust_level = 0;
 349         }
 350
 351         status = git_gpg_config(var, value, cb);
 352         if (status)
 353                 return status;
 354
 355         return git_default_config(var, value, cb);
 356 }
 357
 358 /**
 359  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 360  * into merge_heads.
 361  */
 362 static void get_merge_heads(struct oid_array *merge_heads)
 363 {
 364         const char *filename = git_path_fetch_head(the_repository);
 365         FILE *fp;
 366         struct strbuf sb = STRBUF_INIT;
 367         struct object_id oid;
 368
 369         fp = xfopen(filename, "r");
 370         while (strbuf_getline_lf(&sb, fp) != EOF) {
 371                 const char *p;
 372                 if (parse_oid_hex(sb.buf, &oid, &p))
 373                         continue;  /* invalid line: does not start with object ID */
 374                 if (starts_with(p, "\tnot-for-merge\t"))
 375                         continue;  /* ref is not-for-merge */
 376                 oid_array_append(merge_heads, &oid);
 377         }
 378         fclose(fp);
 379         strbuf_release(&sb);
 380 }
 381
 382 /**
 383  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 384  * retrieve the name of the remote if the repository only has one remote.
 385  */
 386 static int get_only_remote(struct remote *remote, void *cb_data)
 387 {
 388         const char **remote_name = cb_data;
 389
 390         if (*remote_name)
 391                 return -1;
 392
 393         *remote_name = remote->name;
 394         return 0;
 395 }
 396
 397 /**
 398  * Dies with the appropriate reason for why there are no merge candidates:
 399  *
 400  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 401  *    up not fetching anything. This is usually because the user provided a
 402  *    wildcard refspec which had no matches on the remote end.
 403  *
 404  * 2. We fetched from a non-default remote, but didn't specify a branch to
 405  *    merge. We can't use the configured one because it applies to the default
 406  *    remote, thus the user must specify the branches to merge.
 407  *
 408  * 3. We fetched from the branch's or repo's default remote, but:
 409  *
 410  *    a. We are not on a branch, so there will never be a configured branch to
 411  *       merge with.
 412  *
 413  *    b. We are on a branch, but there is no configured branch to merge with.
 414  *
 415  * 4. We fetched from the branch's or repo's default remote, but the configured
 416  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 417  *    part of the configured fetch refspec.)
 418  */
 419 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 420 {
 421         struct branch *curr_branch = branch_get("HEAD");
 422         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 423
 424         if (*refspecs) {
 425                 if (opt_rebase)
 426                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 427                 else
 428                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 429                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 430                                         "matches on the remote end."));
 431         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 432                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 433                         "a branch. Because this is not the default configured remote\n"
 434                         "for your current branch, you must specify a branch on the command line."),
 435                         repo);
 436         } else if (!curr_branch) {
 437                 fprintf_ln(stderr, _("You are not currently on a branch."));
 438                 if (opt_rebase)
 439                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 440                 else
 441                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 442                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 443                 fprintf(stderr, "\n");
 444                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 445                 fprintf(stderr, "\n");
 446         } else if (!curr_branch->merge_nr) {
 447                 const char *remote_name = NULL;
 448
 449                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 450                         remote_name = _("<remote>");
 451
 452                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 453                 if (opt_rebase)
 454                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 455                 else
 456                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 457                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 458                 fprintf(stderr, "\n");
 459                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 460                 fprintf(stderr, "\n");
 461                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 462                 fprintf(stderr, "\n");
 463                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 464                                 remote_name, _("<branch>"), curr_branch->name);
 465         } else
 466                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 467                         "from the remote, but no such ref was fetched."),
 468                         *curr_branch->merge_name);
 469         exit(1);
 470 }
 471
 472 /**
 473  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 474  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 475  * is not provided in argv, it is set to NULL.
 476  */
 477 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 478                 const char ***refspecs)
 479 {
 480         if (argc > 0) {
 481                 *repo = *argv++;
 482                 argc--;
 483         } else
 484                 *repo = NULL;
 485         *refspecs = argv;
 486 }
 487
 488 /**
 489  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 490  * repository and refspecs to fetch, or NULL if they are not provided.
 491  */
 492 static int run_fetch(const char *repo, const char **refspecs)
 493 {
 494         struct argv_array args = ARGV_ARRAY_INIT;
 495         int ret;
 496
 497         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 498
 499         /* Shared options */
 500         argv_push_verbosity(&args);
 501         if (opt_progress)
 502                 argv_array_push(&args, opt_progress);
 503
 504         /* Options passed to git-fetch */
 505         if (opt_all)
 506                 argv_array_push(&args, opt_all);
 507         if (opt_append)
 508                 argv_array_push(&args, opt_append);
 509         if (opt_upload_pack)
 510                 argv_array_push(&args, opt_upload_pack);
 511         argv_push_force(&args);
 512         if (opt_tags)
 513                 argv_array_push(&args, opt_tags);
 514         if (opt_prune)
 515                 argv_array_push(&args, opt_prune);
 516         if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
 517                 switch (recurse_submodules) {
 518                 case RECURSE_SUBMODULES_ON:
 519                         argv_array_push(&args, "--recurse-submodules=on");
 520                         break;
 521                 case RECURSE_SUBMODULES_OFF:
 522                         argv_array_push(&args, "--recurse-submodules=no");
 523                         break;
 524                 case RECURSE_SUBMODULES_ON_DEMAND:
 525                         argv_array_push(&args, "--recurse-submodules=on-demand");
 526                         break;
 527                 default:
 528                         BUG("submodule recursion option not understood");
 529                 }
 530         if (max_children)
 531                 argv_array_push(&args, max_children);
 532         if (opt_dry_run)
 533                 argv_array_push(&args, "--dry-run");
 534         if (opt_keep)
 535                 argv_array_push(&args, opt_keep);
 536         if (opt_depth)
 537                 argv_array_push(&args, opt_depth);
 538         if (opt_unshallow)
 539                 argv_array_push(&args, opt_unshallow);
 540         if (opt_update_shallow)
 541                 argv_array_push(&args, opt_update_shallow);
 542         if (opt_refmap)
 543                 argv_array_push(&args, opt_refmap);
 544         if (opt_ipv4)
 545                 argv_array_push(&args, opt_ipv4);
 546         if (opt_ipv6)
 547                 argv_array_push(&args, opt_ipv6);
 548         if (opt_show_forced_updates > 0)
 549                 argv_array_push(&args, "--show-forced-updates");
 550         else if (opt_show_forced_updates == 0)
 551                 argv_array_push(&args, "--no-show-forced-updates");
 552         if (set_upstream)
 553                 argv_array_push(&args, set_upstream);
 554
 555         if (repo) {
 556                 argv_array_push(&args, repo);
 557                 argv_array_pushv(&args, refspecs);
 558         } else if (*refspecs)
 559                 BUG("refspecs without repo?");
 560         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 561         argv_array_clear(&args);
 562         return ret;
 563 }
 564
 565 /**
 566  * "Pulls into void" by branching off merge_head.
 567  */
 568 static int pull_into_void(const struct object_id *merge_head,
 569                 const struct object_id *curr_head)
 570 {
 571         if (opt_verify_signatures) {
 572                 struct commit *commit;
 573
 574                 commit = lookup_commit(the_repository, merge_head);
 575                 if (!commit)
 576                         die(_("unable to access commit %s"),
 577                             oid_to_hex(merge_head));
 578
 579                 verify_merge_signature(commit, opt_verbosity,
 580                                        check_trust_level);
 581         }
 582
 583         /*
 584          * Two-way merge: we treat the index as based on an empty tree,
 585          * and try to fast-forward to HEAD. This ensures we will not lose
 586          * index/worktree changes that the user already made on the unborn
 587          * branch.
 588          */
 589         if (checkout_fast_forward(the_repository,
 590                                   the_hash_algo->empty_tree,
 591                                   merge_head, 0))
 592                 return 1;
 593
 594         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 595                 return 1;
 596
 597         return 0;
 598 }
 599
 600 static int rebase_submodules(void)
 601 {
 602         struct child_process cp = CHILD_PROCESS_INIT;
 603
 604         cp.git_cmd = 1;
 605         cp.no_stdin = 1;
 606         argv_array_pushl(&cp.args, "submodule", "update",
 607                                    "--recursive", "--rebase", NULL);
 608         argv_push_verbosity(&cp.args);
 609
 610         return run_command(&cp);
 611 }
 612
 613 static int update_submodules(void)
 614 {
 615         struct child_process cp = CHILD_PROCESS_INIT;
 616
 617         cp.git_cmd = 1;
 618         cp.no_stdin = 1;
 619         argv_array_pushl(&cp.args, "submodule", "update",
 620                                    "--recursive", "--checkout", NULL);
 621         argv_push_verbosity(&cp.args);
 622
 623         return run_command(&cp);
 624 }
 625
 626 /**
 627  * Runs git-merge, returning its exit status.
 628  */
 629 static int run_merge(void)
 630 {
 631         int ret;
 632         struct argv_array args = ARGV_ARRAY_INIT;
 633
 634         argv_array_pushl(&args, "merge", NULL);
 635
 636         /* Shared options */
 637         argv_push_verbosity(&args);
 638         if (opt_progress)
 639                 argv_array_push(&args, opt_progress);
 640
 641         /* Options passed to git-merge */
 642         if (opt_diffstat)
 643                 argv_array_push(&args, opt_diffstat);
 644         if (opt_log)
 645                 argv_array_push(&args, opt_log);
 646         if (opt_signoff)
 647                 argv_array_push(&args, opt_signoff);
 648         if (opt_squash)
 649                 argv_array_push(&args, opt_squash);
 650         if (opt_commit)
 651                 argv_array_push(&args, opt_commit);
 652         if (opt_edit)
 653                 argv_array_push(&args, opt_edit);
 654         if (cleanup_arg)
 655                 argv_array_pushf(&args, "--cleanup=%s", cleanup_arg);
 656         if (opt_ff)
 657                 argv_array_push(&args, opt_ff);
 658         if (opt_verify_signatures)
 659                 argv_array_push(&args, opt_verify_signatures);
 660         argv_array_pushv(&args, opt_strategies.argv);
 661         argv_array_pushv(&args, opt_strategy_opts.argv);
 662         if (opt_gpg_sign)
 663                 argv_array_push(&args, opt_gpg_sign);
 664         if (opt_allow_unrelated_histories > 0)
 665                 argv_array_push(&args, "--allow-unrelated-histories");
 666
 667         argv_array_push(&args, "FETCH_HEAD");
 668         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 669         argv_array_clear(&args);
 670         return ret;
 671 }
 672
 673 /**
 674  * Returns remote's upstream branch for the current branch. If remote is NULL,
 675  * the current branch's configured default remote is used. Returns NULL if
 676  * `remote` does not name a valid remote, HEAD does not point to a branch,
 677  * remote is not the branch's configured remote or the branch does not have any
 678  * configured upstream branch.
 679  */
 680 static const char *get_upstream_branch(const char *remote)
 681 {
 682         struct remote *rm;
 683         struct branch *curr_branch;
 684         const char *curr_branch_remote;
 685
 686         rm = remote_get(remote);
 687         if (!rm)
 688                 return NULL;
 689
 690         curr_branch = branch_get("HEAD");
 691         if (!curr_branch)
 692                 return NULL;
 693
 694         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 695         assert(curr_branch_remote);
 696
 697         if (strcmp(curr_branch_remote, rm->name))
 698                 return NULL;
 699
 700         return branch_get_upstream(curr_branch, NULL);
 701 }
 702
 703 /**
 704  * Derives the remote-tracking branch from the remote and refspec.
 705  *
 706  * FIXME: The current implementation assumes the default mapping of
 707  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 708  */
 709 static const char *get_tracking_branch(const char *remote, const char *refspec)
 710 {
 711         struct refspec_item spec;
 712         const char *spec_src;
 713         const char *merge_branch;
 714
 715         refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);
 716         spec_src = spec.src;
 717         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 718                 spec_src = "HEAD";
 719         else if (skip_prefix(spec_src, "heads/", &spec_src))
 720                 ;
 721         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 722                 ;
 723         else if (starts_with(spec_src, "refs/") ||
 724                 starts_with(spec_src, "tags/") ||
 725                 starts_with(spec_src, "remotes/"))
 726                 spec_src = "";
 727
 728         if (*spec_src) {
 729                 if (!strcmp(remote, "."))
 730                         merge_branch = mkpath("refs/heads/%s", spec_src);
 731                 else
 732                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 733         } else
 734                 merge_branch = NULL;
 735
 736         refspec_item_clear(&spec);
 737         return merge_branch;
 738 }
 739
 740 /**
 741  * Given the repo and refspecs, sets fork_point to the point at which the
 742  * current branch forked from its remote-tracking branch. Returns 0 on success,
 743  * -1 on failure.
 744  */
 745 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 746                 const char *refspec)
 747 {
 748         int ret;
 749         struct branch *curr_branch;
 750         const char *remote_branch;
 751         struct child_process cp = CHILD_PROCESS_INIT;
 752         struct strbuf sb = STRBUF_INIT;
 753
 754         curr_branch = branch_get("HEAD");
 755         if (!curr_branch)
 756                 return -1;
 757
 758         if (refspec)
 759                 remote_branch = get_tracking_branch(repo, refspec);
 760         else
 761                 remote_branch = get_upstream_branch(repo);
 762
 763         if (!remote_branch)
 764                 return -1;
 765
 766         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 767                         remote_branch, curr_branch->name, NULL);
 768         cp.no_stdin = 1;
 769         cp.no_stderr = 1;
 770         cp.git_cmd = 1;
 771
 772         ret = capture_command(&cp, &sb, GIT_MAX_HEXSZ);
 773         if (ret)
 774                 goto cleanup;
 775
 776         ret = get_oid_hex(sb.buf, fork_point);
 777         if (ret)
 778                 goto cleanup;
 779
 780 cleanup:
 781         strbuf_release(&sb);
 782         return ret ? -1 : 0;
 783 }
 784
 785 /**
 786  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 787  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 788  */
 789 static int get_octopus_merge_base(struct object_id *merge_base,
 790                 const struct object_id *curr_head,
 791                 const struct object_id *merge_head,
 792                 const struct object_id *fork_point)
 793 {
 794         struct commit_list *revs = NULL, *result;
 795
 796         commit_list_insert(lookup_commit_reference(the_repository, curr_head),
 797                            &revs);
 798         commit_list_insert(lookup_commit_reference(the_repository, merge_head),
 799                            &revs);
 800         if (!is_null_oid(fork_point))
 801                 commit_list_insert(lookup_commit_reference(the_repository, fork_point),
 802                                    &revs);
 803
 804         result = get_octopus_merge_bases(revs);
 805         free_commit_list(revs);
 806         reduce_heads_replace(&result);
 807
 808         if (!result)
 809                 return 1;
 810
 811         oidcpy(merge_base, &result->item->object.oid);
 812         free_commit_list(result);
 813         return 0;
 814 }
 815
 816 /**
 817  * Given the current HEAD oid, the merge head returned from git-fetch and the
 818  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 819  * appropriate arguments and returns its exit status.
 820  */
 821 static int run_rebase(const struct object_id *curr_head,
 822                 const struct object_id *merge_head,
 823                 const struct object_id *fork_point)
 824 {
 825         int ret;
 826         struct object_id oct_merge_base;
 827         struct argv_array args = ARGV_ARRAY_INIT;
 828
 829         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 830                 if (!is_null_oid(fork_point) && oideq(&oct_merge_base, fork_point))
 831                         fork_point = NULL;
 832
 833         argv_array_push(&args, "rebase");
 834
 835         /* Shared options */
 836         argv_push_verbosity(&args);
 837
 838         /* Options passed to git-rebase */
 839         if (opt_rebase == REBASE_MERGES)
 840                 argv_array_push(&args, "--rebase-merges");
 841         else if (opt_rebase == REBASE_PRESERVE)
 842                 argv_array_push(&args, "--preserve-merges");
 843         else if (opt_rebase == REBASE_INTERACTIVE)
 844                 argv_array_push(&args, "--interactive");
 845         if (opt_diffstat)
 846                 argv_array_push(&args, opt_diffstat);
 847         argv_array_pushv(&args, opt_strategies.argv);
 848         argv_array_pushv(&args, opt_strategy_opts.argv);
 849         if (opt_gpg_sign)
 850                 argv_array_push(&args, opt_gpg_sign);
 851         if (opt_autostash == 0)
 852                 argv_array_push(&args, "--no-autostash");
 853         else if (opt_autostash == 1)
 854                 argv_array_push(&args, "--autostash");
 855         if (opt_verify_signatures &&
 856             !strcmp(opt_verify_signatures, "--verify-signatures"))
 857                 warning(_("ignoring --verify-signatures for rebase"));
 858
 859         argv_array_push(&args, "--onto");
 860         argv_array_push(&args, oid_to_hex(merge_head));
 861
 862         if (fork_point && !is_null_oid(fork_point))
 863                 argv_array_push(&args, oid_to_hex(fork_point));
 864         else
 865                 argv_array_push(&args, oid_to_hex(merge_head));
 866
 867         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 868         argv_array_clear(&args);
 869         return ret;
 870 }
 871
 872 int cmd_pull(int argc, const char **argv, const char *prefix)
 873 {
 874         const char *repo, **refspecs;
 875         struct oid_array merge_heads = OID_ARRAY_INIT;
 876         struct object_id orig_head, curr_head;
 877         struct object_id rebase_fork_point;
 878         int autostash;
 879
 880         if (!getenv("GIT_REFLOG_ACTION"))
 881                 set_reflog_message(argc, argv);
 882
 883         git_config(git_pull_config, NULL);
 884
 885         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 886
 887         if (cleanup_arg)
 888                 /*
 889                  * this only checks the validity of cleanup_arg; we don't need
 890                  * a valid value for use_editor
 891                  */
 892                 get_cleanup_mode(cleanup_arg, 0);
 893
 894         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 895
 896         if (!opt_ff)
 897                 opt_ff = xstrdup_or_null(config_get_ff());
 898
 899         if (opt_rebase < 0)
 900                 opt_rebase = config_get_rebase();
 901
 902         if (read_cache_unmerged())
 903                 die_resolve_conflict("pull");
 904
 905         if (file_exists(git_path_merge_head(the_repository)))
 906                 die_conclude_merge();
 907
 908         if (get_oid("HEAD", &orig_head))
 909                 oidclr(&orig_head);
 910
 911         if (!opt_rebase && opt_autostash != -1)
 912                 die(_("--[no-]autostash option is only valid with --rebase."));
 913
 914         autostash = config_autostash;
 915         if (opt_rebase) {
 916                 if (opt_autostash != -1)
 917                         autostash = opt_autostash;
 918
 919                 if (is_null_oid(&orig_head) && !is_cache_unborn())
 920                         die(_("Updating an unborn branch with changes added to the index."));
 921
 922                 if (!autostash)
 923                         require_clean_work_tree(the_repository,
 924                                 N_("pull with rebase"),
 925                                 _("please commit or stash them."), 1, 0);
 926
 927                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
 928                         oidclr(&rebase_fork_point);
 929         }
 930
 931         if (run_fetch(repo, refspecs))
 932                 return 1;
 933
 934         if (opt_dry_run)
 935                 return 0;
 936
 937         if (get_oid("HEAD", &curr_head))
 938                 oidclr(&curr_head);
 939
 940         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
 941                         !oideq(&orig_head, &curr_head)) {
 942                 /*
 943                  * The fetch involved updating the current branch.
 944                  *
 945                  * The working tree and the index file are still based on
 946                  * orig_head commit, but we are merging into curr_head.
 947                  * Update the working tree to match curr_head.
 948                  */
 949
 950                 warning(_("fetch updated the current branch head.\n"
 951                         "fast-forwarding your working tree from\n"
 952                         "commit %s."), oid_to_hex(&orig_head));
 953
 954                 if (checkout_fast_forward(the_repository, &orig_head,
 955                                           &curr_head, 0))
 956                         die(_("Cannot fast-forward your working tree.\n"
 957                                 "After making sure that you saved anything precious from\n"
 958                                 "$ git diff %s\n"
 959                                 "output, run\n"
 960                                 "$ git reset --hard\n"
 961                                 "to recover."), oid_to_hex(&orig_head));
 962         }
 963
 964         get_merge_heads(&merge_heads);
 965
 966         if (!merge_heads.nr)
 967                 die_no_merge_candidates(repo, refspecs);
 968
 969         if (is_null_oid(&orig_head)) {
 970                 if (merge_heads.nr > 1)
 971                         die(_("Cannot merge multiple branches into empty head."));
 972                 return pull_into_void(merge_heads.oid, &curr_head);
 973         }
 974         if (opt_rebase && merge_heads.nr > 1)
 975                 die(_("Cannot rebase onto multiple branches."));
 976
 977         if (opt_rebase) {
 978                 int ret = 0;
 979                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
 980                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
 981                     submodule_touches_in_range(the_repository, &rebase_fork_point, &curr_head))
 982                         die(_("cannot rebase with locally recorded submodule modifications"));
 983                 if (!autostash) {
 984                         struct commit_list *list = NULL;
 985                         struct commit *merge_head, *head;
 986
 987                         head = lookup_commit_reference(the_repository,
 988                                                        &orig_head);
 989                         commit_list_insert(head, &list);
 990                         merge_head = lookup_commit_reference(the_repository,
 991                                                              &merge_heads.oid[0]);
 992                         if (is_descendant_of(merge_head, list)) {
 993                                 /* we can fast-forward this without invoking rebase */
 994                                 opt_ff = "--ff-only";
 995                                 ret = run_merge();
 996                         }
 997                 }
 998                 ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
 999
1000                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1001                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1002                         ret = rebase_submodules();
1003
1004                 return ret;
1005         } else {
1006                 int ret = run_merge();
1007                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1008                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1009                         ret = update_submodules();
1010                 return ret;
1011         }
1012 }