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 strvec opt_strategies = STRVEC_INIT;
  91 static struct strvec opt_strategy_opts = STRVEC_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 static struct strvec opt_fetch = STRVEC_INIT;
 114
 115 static struct option pull_options[] = {
 116         /* Shared options */
 117         OPT__VERBOSITY(&opt_verbosity),
 118         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 119                 N_("force progress reporting"),
 120                 PARSE_OPT_NOARG),
 121         OPT_CALLBACK_F(0, "recurse-submodules",
 122                    &recurse_submodules, N_("on-demand"),
 123                    N_("control for recursive fetching of submodules"),
 124                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules),
 125
 126         /* Options passed to git-merge or git-rebase */
 127         OPT_GROUP(N_("Options related to merging")),
 128         OPT_CALLBACK_F('r', "rebase", &opt_rebase,
 129           "(false|true|merges|preserve|interactive)",
 130           N_("incorporate changes by rebasing rather than merging"),
 131           PARSE_OPT_OPTARG, parse_opt_rebase),
 132         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 133                 N_("do not show a diffstat at the end of the merge"),
 134                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 135         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 136                 N_("show a diffstat at the end of the merge"),
 137                 PARSE_OPT_NOARG),
 138         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 139                 N_("(synonym to --stat)"),
 140                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 141         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 142                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 143                 PARSE_OPT_OPTARG),
 144         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 145                 N_("add Signed-off-by:"),
 146                 PARSE_OPT_OPTARG),
 147         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 148                 N_("create a single commit instead of doing a merge"),
 149                 PARSE_OPT_NOARG),
 150         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 151                 N_("perform a commit if the merge succeeds (default)"),
 152                 PARSE_OPT_NOARG),
 153         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 154                 N_("edit message before committing"),
 155                 PARSE_OPT_NOARG),
 156         OPT_CLEANUP(&cleanup_arg),
 157         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 158                 N_("allow fast-forward"),
 159                 PARSE_OPT_NOARG),
 160         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 161                 N_("abort if fast-forward is not possible"),
 162                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 163         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 164                 N_("verify that the named commit has a valid GPG signature"),
 165                 PARSE_OPT_NOARG),
 166         OPT_BOOL(0, "autostash", &opt_autostash,
 167                 N_("automatically stash/stash pop before and after")),
 168         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 169                 N_("merge strategy to use"),
 170                 0),
 171         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 172                 N_("option=value"),
 173                 N_("option for selected merge strategy"),
 174                 0),
 175         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 176                 N_("GPG sign commit"),
 177                 PARSE_OPT_OPTARG),
 178         OPT_SET_INT(0, "allow-unrelated-histories",
 179                     &opt_allow_unrelated_histories,
 180                     N_("allow merging unrelated histories"), 1),
 181
 182         /* Options passed to git-fetch */
 183         OPT_GROUP(N_("Options related to fetching")),
 184         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 185                 N_("fetch from all remotes"),
 186                 PARSE_OPT_NOARG),
 187         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 188                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 189                 PARSE_OPT_NOARG),
 190         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 191                 N_("path to upload pack on remote end"),
 192                 0),
 193         OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),
 194         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 195                 N_("fetch all tags and associated objects"),
 196                 PARSE_OPT_NOARG),
 197         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 198                 N_("prune remote-tracking branches no longer on remote"),
 199                 PARSE_OPT_NOARG),
 200         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 201                 N_("number of submodules pulled in parallel"),
 202                 PARSE_OPT_OPTARG),
 203         OPT_BOOL(0, "dry-run", &opt_dry_run,
 204                 N_("dry run")),
 205         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 206                 N_("keep downloaded pack"),
 207                 PARSE_OPT_NOARG),
 208         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 209                 N_("deepen history of shallow clone"),
 210                 0),
 211         OPT_PASSTHRU_ARGV(0, "shallow-since", &opt_fetch, N_("time"),
 212                 N_("deepen history of shallow repository based on time"),
 213                 0),
 214         OPT_PASSTHRU_ARGV(0, "shallow-exclude", &opt_fetch, N_("revision"),
 215                 N_("deepen history of shallow clone, excluding rev"),
 216                 0),
 217         OPT_PASSTHRU_ARGV(0, "deepen", &opt_fetch, N_("n"),
 218                 N_("deepen history of shallow clone"),
 219                 0),
 220         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 221                 N_("convert to a complete repository"),
 222                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 223         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 224                 N_("accept refs that update .git/shallow"),
 225                 PARSE_OPT_NOARG),
 226         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 227                 N_("specify fetch refmap"),
 228                 PARSE_OPT_NONEG),
 229         OPT_PASSTHRU_ARGV('o', "server-option", &opt_fetch,
 230                 N_("server-specific"),
 231                 N_("option to transmit"),
 232                 0),
 233         OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,
 234                 N_("use IPv4 addresses only"),
 235                 PARSE_OPT_NOARG),
 236         OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 237                 N_("use IPv6 addresses only"),
 238                 PARSE_OPT_NOARG),
 239         OPT_PASSTHRU_ARGV(0, "negotiation-tip", &opt_fetch, N_("revision"),
 240                 N_("report that we have only objects reachable from this object"),
 241                 0),
 242         OPT_BOOL(0, "show-forced-updates", &opt_show_forced_updates,
 243                  N_("check for forced-updates on all updated branches")),
 244         OPT_PASSTHRU(0, "set-upstream", &set_upstream, NULL,
 245                 N_("set upstream for git pull/fetch"),
 246                 PARSE_OPT_NOARG),
 247
 248         OPT_END()
 249 };
 250
 251 /**
 252  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 253  */
 254 static void argv_push_verbosity(struct strvec *arr)
 255 {
 256         int verbosity;
 257
 258         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 259                 strvec_push(arr, "-v");
 260
 261         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 262                 strvec_push(arr, "-q");
 263 }
 264
 265 /**
 266  * Pushes "-f" switches into arr to match the opt_force level.
 267  */
 268 static void argv_push_force(struct strvec *arr)
 269 {
 270         int force = opt_force;
 271         while (force-- > 0)
 272                 strvec_push(arr, "-f");
 273 }
 274
 275 /**
 276  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 277  */
 278 static void set_reflog_message(int argc, const char **argv)
 279 {
 280         int i;
 281         struct strbuf msg = STRBUF_INIT;
 282
 283         for (i = 0; i < argc; i++) {
 284                 if (i)
 285                         strbuf_addch(&msg, ' ');
 286                 strbuf_addstr(&msg, argv[i]);
 287         }
 288
 289         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 290
 291         strbuf_release(&msg);
 292 }
 293
 294 /**
 295  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 296  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 297  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 298  * error.
 299  */
 300 static const char *config_get_ff(void)
 301 {
 302         const char *value;
 303
 304         if (git_config_get_value("pull.ff", &value))
 305                 return NULL;
 306
 307         switch (git_parse_maybe_bool(value)) {
 308         case 0:
 309                 return "--no-ff";
 310         case 1:
 311                 return "--ff";
 312         }
 313
 314         if (!strcmp(value, "only"))
 315                 return "--ff-only";
 316
 317         die(_("Invalid value for pull.ff: %s"), value);
 318 }
 319
 320 /**
 321  * Returns the default configured value for --rebase. It first looks for the
 322  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 323  * branch, and if HEAD is detached or the configuration key does not exist,
 324  * looks for the value of "pull.rebase". If both configuration keys do not
 325  * exist, returns REBASE_FALSE.
 326  */
 327 static enum rebase_type config_get_rebase(void)
 328 {
 329         struct branch *curr_branch = branch_get("HEAD");
 330         const char *value;
 331
 332         if (curr_branch) {
 333                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 334
 335                 if (!git_config_get_value(key, &value)) {
 336                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 337                         free(key);
 338                         return ret;
 339                 }
 340
 341                 free(key);
 342         }
 343
 344         if (!git_config_get_value("pull.rebase", &value))
 345                 return parse_config_rebase("pull.rebase", value, 1);
 346
 347         if (opt_verbosity >= 0 &&
 348             (!opt_ff || strcmp(opt_ff, "--ff-only"))) {
 349                 warning(_("Pulling without specifying how to reconcile divergent branches is\n"
 350                         "discouraged. You can squelch this message by running one of the following\n"
 351                         "commands sometime before your next pull:\n"
 352                         "\n"
 353                         "  git config pull.rebase false  # merge (the default strategy)\n"
 354                         "  git config pull.rebase true   # rebase\n"
 355                         "  git config pull.ff only       # fast-forward only\n"
 356                         "\n"
 357                         "You can replace \"git config\" with \"git config --global\" to set a default\n"
 358                         "preference for all repositories. You can also pass --rebase, --no-rebase,\n"
 359                         "or --ff-only on the command line to override the configured default per\n"
 360                         "invocation.\n"));
 361         }
 362
 363         return REBASE_FALSE;
 364 }
 365
 366 /**
 367  * Read config variables.
 368  */
 369 static int git_pull_config(const char *var, const char *value, void *cb)
 370 {
 371         int status;
 372
 373         if (!strcmp(var, "rebase.autostash")) {
 374                 config_autostash = git_config_bool(var, value);
 375                 return 0;
 376         } else if (!strcmp(var, "submodule.recurse")) {
 377                 recurse_submodules = git_config_bool(var, value) ?
 378                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 379                 return 0;
 380         } else if (!strcmp(var, "gpg.mintrustlevel")) {
 381                 check_trust_level = 0;
 382         }
 383
 384         status = git_gpg_config(var, value, cb);
 385         if (status)
 386                 return status;
 387
 388         return git_default_config(var, value, cb);
 389 }
 390
 391 /**
 392  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 393  * into merge_heads.
 394  */
 395 static void get_merge_heads(struct oid_array *merge_heads)
 396 {
 397         const char *filename = git_path_fetch_head(the_repository);
 398         FILE *fp;
 399         struct strbuf sb = STRBUF_INIT;
 400         struct object_id oid;
 401
 402         fp = xfopen(filename, "r");
 403         while (strbuf_getline_lf(&sb, fp) != EOF) {
 404                 const char *p;
 405                 if (parse_oid_hex(sb.buf, &oid, &p))
 406                         continue;  /* invalid line: does not start with object ID */
 407                 if (starts_with(p, "\tnot-for-merge\t"))
 408                         continue;  /* ref is not-for-merge */
 409                 oid_array_append(merge_heads, &oid);
 410         }
 411         fclose(fp);
 412         strbuf_release(&sb);
 413 }
 414
 415 /**
 416  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 417  * retrieve the name of the remote if the repository only has one remote.
 418  */
 419 static int get_only_remote(struct remote *remote, void *cb_data)
 420 {
 421         const char **remote_name = cb_data;
 422
 423         if (*remote_name)
 424                 return -1;
 425
 426         *remote_name = remote->name;
 427         return 0;
 428 }
 429
 430 /**
 431  * Dies with the appropriate reason for why there are no merge candidates:
 432  *
 433  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 434  *    up not fetching anything. This is usually because the user provided a
 435  *    wildcard refspec which had no matches on the remote end.
 436  *
 437  * 2. We fetched from a non-default remote, but didn't specify a branch to
 438  *    merge. We can't use the configured one because it applies to the default
 439  *    remote, thus the user must specify the branches to merge.
 440  *
 441  * 3. We fetched from the branch's or repo's default remote, but:
 442  *
 443  *    a. We are not on a branch, so there will never be a configured branch to
 444  *       merge with.
 445  *
 446  *    b. We are on a branch, but there is no configured branch to merge with.
 447  *
 448  * 4. We fetched from the branch's or repo's default remote, but the configured
 449  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 450  *    part of the configured fetch refspec.)
 451  */
 452 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 453 {
 454         struct branch *curr_branch = branch_get("HEAD");
 455         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 456
 457         if (*refspecs) {
 458                 if (opt_rebase)
 459                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 460                 else
 461                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 462                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 463                                         "matches on the remote end."));
 464         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 465                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 466                         "a branch. Because this is not the default configured remote\n"
 467                         "for your current branch, you must specify a branch on the command line."),
 468                         repo);
 469         } else if (!curr_branch) {
 470                 fprintf_ln(stderr, _("You are not currently on a branch."));
 471                 if (opt_rebase)
 472                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 473                 else
 474                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 475                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 476                 fprintf(stderr, "\n");
 477                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 478                 fprintf(stderr, "\n");
 479         } else if (!curr_branch->merge_nr) {
 480                 const char *remote_name = NULL;
 481
 482                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 483                         remote_name = _("<remote>");
 484
 485                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 486                 if (opt_rebase)
 487                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 488                 else
 489                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 490                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 491                 fprintf(stderr, "\n");
 492                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 493                 fprintf(stderr, "\n");
 494                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 495                 fprintf(stderr, "\n");
 496                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 497                                 remote_name, _("<branch>"), curr_branch->name);
 498         } else
 499                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 500                         "from the remote, but no such ref was fetched."),
 501                         *curr_branch->merge_name);
 502         exit(1);
 503 }
 504
 505 /**
 506  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 507  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 508  * is not provided in argv, it is set to NULL.
 509  */
 510 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 511                 const char ***refspecs)
 512 {
 513         if (argc > 0) {
 514                 *repo = *argv++;
 515                 argc--;
 516         } else
 517                 *repo = NULL;
 518         *refspecs = argv;
 519 }
 520
 521 /**
 522  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 523  * repository and refspecs to fetch, or NULL if they are not provided.
 524  */
 525 static int run_fetch(const char *repo, const char **refspecs)
 526 {
 527         struct strvec args = STRVEC_INIT;
 528         int ret;
 529
 530         strvec_pushl(&args, "fetch", "--update-head-ok", NULL);
 531
 532         /* Shared options */
 533         argv_push_verbosity(&args);
 534         if (opt_progress)
 535                 strvec_push(&args, opt_progress);
 536
 537         /* Options passed to git-fetch */
 538         if (opt_all)
 539                 strvec_push(&args, opt_all);
 540         if (opt_append)
 541                 strvec_push(&args, opt_append);
 542         if (opt_upload_pack)
 543                 strvec_push(&args, opt_upload_pack);
 544         argv_push_force(&args);
 545         if (opt_tags)
 546                 strvec_push(&args, opt_tags);
 547         if (opt_prune)
 548                 strvec_push(&args, opt_prune);
 549         if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
 550                 switch (recurse_submodules) {
 551                 case RECURSE_SUBMODULES_ON:
 552                         strvec_push(&args, "--recurse-submodules=on");
 553                         break;
 554                 case RECURSE_SUBMODULES_OFF:
 555                         strvec_push(&args, "--recurse-submodules=no");
 556                         break;
 557                 case RECURSE_SUBMODULES_ON_DEMAND:
 558                         strvec_push(&args, "--recurse-submodules=on-demand");
 559                         break;
 560                 default:
 561                         BUG("submodule recursion option not understood");
 562                 }
 563         if (max_children)
 564                 strvec_push(&args, max_children);
 565         if (opt_dry_run)
 566                 strvec_push(&args, "--dry-run");
 567         if (opt_keep)
 568                 strvec_push(&args, opt_keep);
 569         if (opt_depth)
 570                 strvec_push(&args, opt_depth);
 571         if (opt_unshallow)
 572                 strvec_push(&args, opt_unshallow);
 573         if (opt_update_shallow)
 574                 strvec_push(&args, opt_update_shallow);
 575         if (opt_refmap)
 576                 strvec_push(&args, opt_refmap);
 577         if (opt_ipv4)
 578                 strvec_push(&args, opt_ipv4);
 579         if (opt_ipv6)
 580                 strvec_push(&args, opt_ipv6);
 581         if (opt_show_forced_updates > 0)
 582                 strvec_push(&args, "--show-forced-updates");
 583         else if (opt_show_forced_updates == 0)
 584                 strvec_push(&args, "--no-show-forced-updates");
 585         if (set_upstream)
 586                 strvec_push(&args, set_upstream);
 587         strvec_pushv(&args, opt_fetch.v);
 588
 589         if (repo) {
 590                 strvec_push(&args, repo);
 591                 strvec_pushv(&args, refspecs);
 592         } else if (*refspecs)
 593                 BUG("refspecs without repo?");
 594         ret = run_command_v_opt(args.v, RUN_GIT_CMD);
 595         strvec_clear(&args);
 596         return ret;
 597 }
 598
 599 /**
 600  * "Pulls into void" by branching off merge_head.
 601  */
 602 static int pull_into_void(const struct object_id *merge_head,
 603                 const struct object_id *curr_head)
 604 {
 605         if (opt_verify_signatures) {
 606                 struct commit *commit;
 607
 608                 commit = lookup_commit(the_repository, merge_head);
 609                 if (!commit)
 610                         die(_("unable to access commit %s"),
 611                             oid_to_hex(merge_head));
 612
 613                 verify_merge_signature(commit, opt_verbosity,
 614                                        check_trust_level);
 615         }
 616
 617         /*
 618          * Two-way merge: we treat the index as based on an empty tree,
 619          * and try to fast-forward to HEAD. This ensures we will not lose
 620          * index/worktree changes that the user already made on the unborn
 621          * branch.
 622          */
 623         if (checkout_fast_forward(the_repository,
 624                                   the_hash_algo->empty_tree,
 625                                   merge_head, 0))
 626                 return 1;
 627
 628         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 629                 return 1;
 630
 631         return 0;
 632 }
 633
 634 static int rebase_submodules(void)
 635 {
 636         struct child_process cp = CHILD_PROCESS_INIT;
 637
 638         cp.git_cmd = 1;
 639         cp.no_stdin = 1;
 640         strvec_pushl(&cp.args, "submodule", "update",
 641                      "--recursive", "--rebase", NULL);
 642         argv_push_verbosity(&cp.args);
 643
 644         return run_command(&cp);
 645 }
 646
 647 static int update_submodules(void)
 648 {
 649         struct child_process cp = CHILD_PROCESS_INIT;
 650
 651         cp.git_cmd = 1;
 652         cp.no_stdin = 1;
 653         strvec_pushl(&cp.args, "submodule", "update",
 654                      "--recursive", "--checkout", NULL);
 655         argv_push_verbosity(&cp.args);
 656
 657         return run_command(&cp);
 658 }
 659
 660 /**
 661  * Runs git-merge, returning its exit status.
 662  */
 663 static int run_merge(void)
 664 {
 665         int ret;
 666         struct strvec args = STRVEC_INIT;
 667
 668         strvec_pushl(&args, "merge", NULL);
 669
 670         /* Shared options */
 671         argv_push_verbosity(&args);
 672         if (opt_progress)
 673                 strvec_push(&args, opt_progress);
 674
 675         /* Options passed to git-merge */
 676         if (opt_diffstat)
 677                 strvec_push(&args, opt_diffstat);
 678         if (opt_log)
 679                 strvec_push(&args, opt_log);
 680         if (opt_signoff)
 681                 strvec_push(&args, opt_signoff);
 682         if (opt_squash)
 683                 strvec_push(&args, opt_squash);
 684         if (opt_commit)
 685                 strvec_push(&args, opt_commit);
 686         if (opt_edit)
 687                 strvec_push(&args, opt_edit);
 688         if (cleanup_arg)
 689                 strvec_pushf(&args, "--cleanup=%s", cleanup_arg);
 690         if (opt_ff)
 691                 strvec_push(&args, opt_ff);
 692         if (opt_verify_signatures)
 693                 strvec_push(&args, opt_verify_signatures);
 694         strvec_pushv(&args, opt_strategies.v);
 695         strvec_pushv(&args, opt_strategy_opts.v);
 696         if (opt_gpg_sign)
 697                 strvec_push(&args, opt_gpg_sign);
 698         if (opt_autostash == 0)
 699                 strvec_push(&args, "--no-autostash");
 700         else if (opt_autostash == 1)
 701                 strvec_push(&args, "--autostash");
 702         if (opt_allow_unrelated_histories > 0)
 703                 strvec_push(&args, "--allow-unrelated-histories");
 704
 705         strvec_push(&args, "FETCH_HEAD");
 706         ret = run_command_v_opt(args.v, RUN_GIT_CMD);
 707         strvec_clear(&args);
 708         return ret;
 709 }
 710
 711 /**
 712  * Returns remote's upstream branch for the current branch. If remote is NULL,
 713  * the current branch's configured default remote is used. Returns NULL if
 714  * `remote` does not name a valid remote, HEAD does not point to a branch,
 715  * remote is not the branch's configured remote or the branch does not have any
 716  * configured upstream branch.
 717  */
 718 static const char *get_upstream_branch(const char *remote)
 719 {
 720         struct remote *rm;
 721         struct branch *curr_branch;
 722         const char *curr_branch_remote;
 723
 724         rm = remote_get(remote);
 725         if (!rm)
 726                 return NULL;
 727
 728         curr_branch = branch_get("HEAD");
 729         if (!curr_branch)
 730                 return NULL;
 731
 732         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 733         assert(curr_branch_remote);
 734
 735         if (strcmp(curr_branch_remote, rm->name))
 736                 return NULL;
 737
 738         return branch_get_upstream(curr_branch, NULL);
 739 }
 740
 741 /**
 742  * Derives the remote-tracking branch from the remote and refspec.
 743  *
 744  * FIXME: The current implementation assumes the default mapping of
 745  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 746  */
 747 static const char *get_tracking_branch(const char *remote, const char *refspec)
 748 {
 749         struct refspec_item spec;
 750         const char *spec_src;
 751         const char *merge_branch;
 752
 753         refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);
 754         spec_src = spec.src;
 755         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 756                 spec_src = "HEAD";
 757         else if (skip_prefix(spec_src, "heads/", &spec_src))
 758                 ;
 759         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 760                 ;
 761         else if (starts_with(spec_src, "refs/") ||
 762                 starts_with(spec_src, "tags/") ||
 763                 starts_with(spec_src, "remotes/"))
 764                 spec_src = "";
 765
 766         if (*spec_src) {
 767                 if (!strcmp(remote, "."))
 768                         merge_branch = mkpath("refs/heads/%s", spec_src);
 769                 else
 770                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 771         } else
 772                 merge_branch = NULL;
 773
 774         refspec_item_clear(&spec);
 775         return merge_branch;
 776 }
 777
 778 /**
 779  * Given the repo and refspecs, sets fork_point to the point at which the
 780  * current branch forked from its remote-tracking branch. Returns 0 on success,
 781  * -1 on failure.
 782  */
 783 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 784                 const char *refspec)
 785 {
 786         int ret;
 787         struct branch *curr_branch;
 788         const char *remote_branch;
 789         struct child_process cp = CHILD_PROCESS_INIT;
 790         struct strbuf sb = STRBUF_INIT;
 791
 792         curr_branch = branch_get("HEAD");
 793         if (!curr_branch)
 794                 return -1;
 795
 796         if (refspec)
 797                 remote_branch = get_tracking_branch(repo, refspec);
 798         else
 799                 remote_branch = get_upstream_branch(repo);
 800
 801         if (!remote_branch)
 802                 return -1;
 803
 804         strvec_pushl(&cp.args, "merge-base", "--fork-point",
 805                      remote_branch, curr_branch->name, NULL);
 806         cp.no_stdin = 1;
 807         cp.no_stderr = 1;
 808         cp.git_cmd = 1;
 809
 810         ret = capture_command(&cp, &sb, GIT_MAX_HEXSZ);
 811         if (ret)
 812                 goto cleanup;
 813
 814         ret = get_oid_hex(sb.buf, fork_point);
 815         if (ret)
 816                 goto cleanup;
 817
 818 cleanup:
 819         strbuf_release(&sb);
 820         return ret ? -1 : 0;
 821 }
 822
 823 /**
 824  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 825  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 826  */
 827 static int get_octopus_merge_base(struct object_id *merge_base,
 828                 const struct object_id *curr_head,
 829                 const struct object_id *merge_head,
 830                 const struct object_id *fork_point)
 831 {
 832         struct commit_list *revs = NULL, *result;
 833
 834         commit_list_insert(lookup_commit_reference(the_repository, curr_head),
 835                            &revs);
 836         commit_list_insert(lookup_commit_reference(the_repository, merge_head),
 837                            &revs);
 838         if (!is_null_oid(fork_point))
 839                 commit_list_insert(lookup_commit_reference(the_repository, fork_point),
 840                                    &revs);
 841
 842         result = get_octopus_merge_bases(revs);
 843         free_commit_list(revs);
 844         reduce_heads_replace(&result);
 845
 846         if (!result)
 847                 return 1;
 848
 849         oidcpy(merge_base, &result->item->object.oid);
 850         free_commit_list(result);
 851         return 0;
 852 }
 853
 854 /**
 855  * Given the current HEAD oid, the merge head returned from git-fetch and the
 856  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 857  * appropriate arguments and returns its exit status.
 858  */
 859 static int run_rebase(const struct object_id *curr_head,
 860                 const struct object_id *merge_head,
 861                 const struct object_id *fork_point)
 862 {
 863         int ret;
 864         struct object_id oct_merge_base;
 865         struct strvec args = STRVEC_INIT;
 866
 867         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 868                 if (!is_null_oid(fork_point) && oideq(&oct_merge_base, fork_point))
 869                         fork_point = NULL;
 870
 871         strvec_push(&args, "rebase");
 872
 873         /* Shared options */
 874         argv_push_verbosity(&args);
 875
 876         /* Options passed to git-rebase */
 877         if (opt_rebase == REBASE_MERGES)
 878                 strvec_push(&args, "--rebase-merges");
 879         else if (opt_rebase == REBASE_PRESERVE)
 880                 strvec_push(&args, "--preserve-merges");
 881         else if (opt_rebase == REBASE_INTERACTIVE)
 882                 strvec_push(&args, "--interactive");
 883         if (opt_diffstat)
 884                 strvec_push(&args, opt_diffstat);
 885         strvec_pushv(&args, opt_strategies.v);
 886         strvec_pushv(&args, opt_strategy_opts.v);
 887         if (opt_gpg_sign)
 888                 strvec_push(&args, opt_gpg_sign);
 889         if (opt_autostash == 0)
 890                 strvec_push(&args, "--no-autostash");
 891         else if (opt_autostash == 1)
 892                 strvec_push(&args, "--autostash");
 893         if (opt_verify_signatures &&
 894             !strcmp(opt_verify_signatures, "--verify-signatures"))
 895                 warning(_("ignoring --verify-signatures for rebase"));
 896
 897         strvec_push(&args, "--onto");
 898         strvec_push(&args, oid_to_hex(merge_head));
 899
 900         if (fork_point && !is_null_oid(fork_point))
 901                 strvec_push(&args, oid_to_hex(fork_point));
 902         else
 903                 strvec_push(&args, oid_to_hex(merge_head));
 904
 905         ret = run_command_v_opt(args.v, RUN_GIT_CMD);
 906         strvec_clear(&args);
 907         return ret;
 908 }
 909
 910 int cmd_pull(int argc, const char **argv, const char *prefix)
 911 {
 912         const char *repo, **refspecs;
 913         struct oid_array merge_heads = OID_ARRAY_INIT;
 914         struct object_id orig_head, curr_head;
 915         struct object_id rebase_fork_point;
 916         int autostash;
 917
 918         if (!getenv("GIT_REFLOG_ACTION"))
 919                 set_reflog_message(argc, argv);
 920
 921         git_config(git_pull_config, NULL);
 922
 923         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 924
 925         if (cleanup_arg)
 926                 /*
 927                  * this only checks the validity of cleanup_arg; we don't need
 928                  * a valid value for use_editor
 929                  */
 930                 get_cleanup_mode(cleanup_arg, 0);
 931
 932         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 933
 934         if (!opt_ff)
 935                 opt_ff = xstrdup_or_null(config_get_ff());
 936
 937         if (opt_rebase < 0)
 938                 opt_rebase = config_get_rebase();
 939
 940         if (read_cache_unmerged())
 941                 die_resolve_conflict("pull");
 942
 943         if (file_exists(git_path_merge_head(the_repository)))
 944                 die_conclude_merge();
 945
 946         if (get_oid("HEAD", &orig_head))
 947                 oidclr(&orig_head);
 948
 949         autostash = config_autostash;
 950         if (opt_rebase) {
 951                 if (opt_autostash != -1)
 952                         autostash = opt_autostash;
 953
 954                 if (is_null_oid(&orig_head) && !is_cache_unborn())
 955                         die(_("Updating an unborn branch with changes added to the index."));
 956
 957                 if (!autostash)
 958                         require_clean_work_tree(the_repository,
 959                                 N_("pull with rebase"),
 960                                 _("please commit or stash them."), 1, 0);
 961
 962                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
 963                         oidclr(&rebase_fork_point);
 964         }
 965
 966         if (run_fetch(repo, refspecs))
 967                 return 1;
 968
 969         if (opt_dry_run)
 970                 return 0;
 971
 972         if (get_oid("HEAD", &curr_head))
 973                 oidclr(&curr_head);
 974
 975         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
 976                         !oideq(&orig_head, &curr_head)) {
 977                 /*
 978                  * The fetch involved updating the current branch.
 979                  *
 980                  * The working tree and the index file are still based on
 981                  * orig_head commit, but we are merging into curr_head.
 982                  * Update the working tree to match curr_head.
 983                  */
 984
 985                 warning(_("fetch updated the current branch head.\n"
 986                         "fast-forwarding your working tree from\n"
 987                         "commit %s."), oid_to_hex(&orig_head));
 988
 989                 if (checkout_fast_forward(the_repository, &orig_head,
 990                                           &curr_head, 0))
 991                         die(_("Cannot fast-forward your working tree.\n"
 992                                 "After making sure that you saved anything precious from\n"
 993                                 "$ git diff %s\n"
 994                                 "output, run\n"
 995                                 "$ git reset --hard\n"
 996                                 "to recover."), oid_to_hex(&orig_head));
 997         }
 998
 999         get_merge_heads(&merge_heads);
1000
1001         if (!merge_heads.nr)
1002                 die_no_merge_candidates(repo, refspecs);
1003
1004         if (is_null_oid(&orig_head)) {
1005                 if (merge_heads.nr > 1)
1006                         die(_("Cannot merge multiple branches into empty head."));
1007                 return pull_into_void(merge_heads.oid, &curr_head);
1008         }
1009         if (opt_rebase && merge_heads.nr > 1)
1010                 die(_("Cannot rebase onto multiple branches."));
1011
1012         if (opt_rebase) {
1013                 int ret = 0;
1014                 int ran_ff = 0;
1015                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
1016                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
1017                     submodule_touches_in_range(the_repository, &rebase_fork_point, &curr_head))
1018                         die(_("cannot rebase with locally recorded submodule modifications"));
1019                 if (!autostash) {
1020                         struct commit_list *list = NULL;
1021                         struct commit *merge_head, *head;
1022
1023                         head = lookup_commit_reference(the_repository,
1024                                                        &orig_head);
1025                         commit_list_insert(head, &list);
1026                         merge_head = lookup_commit_reference(the_repository,
1027                                                              &merge_heads.oid[0]);
1028                         if (repo_is_descendant_of(the_repository,
1029                                                   merge_head, list)) {
1030                                 /* we can fast-forward this without invoking rebase */
1031                                 opt_ff = "--ff-only";
1032                                 ran_ff = 1;
1033                                 ret = run_merge();
1034                         }
1035                         free_commit_list(list);
1036                 }
1037                 if (!ran_ff)
1038                         ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
1039
1040                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1041                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1042                         ret = rebase_submodules();
1043
1044                 return ret;
1045         } else {
1046                 int ret = run_merge();
1047                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1048                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1049                         ret = update_submodules();
1050                 return ret;
1051         }
1052 }