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_VARIABLE
   9 #include "cache.h"
  10 #include "advice.h"
  11 #include "config.h"
  12 #include "builtin.h"
  13 #include "gettext.h"
  14 #include "hex.h"
  15 #include "object-name.h"
  16 #include "parse-options.h"
  17 #include "exec-cmd.h"
  18 #include "run-command.h"
  19 #include "oid-array.h"
  20 #include "remote.h"
  21 #include "dir.h"
  22 #include "rebase.h"
  23 #include "refs.h"
  24 #include "refspec.h"
  25 #include "revision.h"
  26 #include "submodule.h"
  27 #include "submodule-config.h"
  28 #include "tempfile.h"
  29 #include "lockfile.h"
  30 #include "wt-status.h"
  31 #include "commit-reach.h"
  32 #include "sequencer.h"
  33 #include "packfile.h"
  34
  35 /**
  36  * Parses the value of --rebase. If value is a false value, returns
  37  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  38  * "merges", returns REBASE_MERGES. If value is a invalid value, dies with
  39  * a fatal error if fatal is true, otherwise returns REBASE_INVALID.
  40  */
  41 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  42                 int fatal)
  43 {
  44         enum rebase_type v = rebase_parse_value(value);
  45         if (v != REBASE_INVALID)
  46                 return v;
  47
  48         if (fatal)
  49                 die(_("invalid value for '%s': '%s'"), key, value);
  50         else
  51                 error(_("invalid value for '%s': '%s'"), key, value);
  52
  53         return REBASE_INVALID;
  54 }
  55
  56 /**
  57  * Callback for --rebase, which parses arg with parse_config_rebase().
  58  */
  59 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  60 {
  61         enum rebase_type *value = opt->value;
  62
  63         if (arg)
  64                 *value = parse_config_rebase("--rebase", arg, 0);
  65         else
  66                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  67         return *value == REBASE_INVALID ? -1 : 0;
  68 }
  69
  70 static const char * const pull_usage[] = {
  71         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  72         NULL
  73 };
  74
  75 /* Shared options */
  76 static int opt_verbosity;
  77 static char *opt_progress;
  78 static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
  79 static int recurse_submodules_cli = RECURSE_SUBMODULES_DEFAULT;
  80
  81 /* Options passed to git-merge or git-rebase */
  82 static enum rebase_type opt_rebase = -1;
  83 static char *opt_diffstat;
  84 static char *opt_log;
  85 static char *opt_signoff;
  86 static char *opt_squash;
  87 static char *opt_commit;
  88 static char *opt_edit;
  89 static char *cleanup_arg;
  90 static char *opt_ff;
  91 static char *opt_verify_signatures;
  92 static char *opt_verify;
  93 static int opt_autostash = -1;
  94 static int config_autostash;
  95 static int check_trust_level = 1;
  96 static struct strvec opt_strategies = STRVEC_INIT;
  97 static struct strvec opt_strategy_opts = STRVEC_INIT;
  98 static char *opt_gpg_sign;
  99 static int opt_allow_unrelated_histories;
 100
 101 /* Options passed to git-fetch */
 102 static char *opt_all;
 103 static char *opt_append;
 104 static char *opt_upload_pack;
 105 static int opt_force;
 106 static char *opt_tags;
 107 static char *opt_prune;
 108 static char *max_children;
 109 static int opt_dry_run;
 110 static char *opt_keep;
 111 static char *opt_depth;
 112 static char *opt_unshallow;
 113 static char *opt_update_shallow;
 114 static char *opt_refmap;
 115 static char *opt_ipv4;
 116 static char *opt_ipv6;
 117 static int opt_show_forced_updates = -1;
 118 static char *set_upstream;
 119 static struct strvec opt_fetch = STRVEC_INIT;
 120
 121 static struct option pull_options[] = {
 122         /* Shared options */
 123         OPT__VERBOSITY(&opt_verbosity),
 124         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 125                 N_("force progress reporting"),
 126                 PARSE_OPT_NOARG),
 127         OPT_CALLBACK_F(0, "recurse-submodules",
 128                    &recurse_submodules_cli, N_("on-demand"),
 129                    N_("control for recursive fetching of submodules"),
 130                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules),
 131
 132         /* Options passed to git-merge or git-rebase */
 133         OPT_GROUP(N_("Options related to merging")),
 134         OPT_CALLBACK_F('r', "rebase", &opt_rebase,
 135                 "(false|true|merges|interactive)",
 136                 N_("incorporate changes by rebasing rather than merging"),
 137                 PARSE_OPT_OPTARG, parse_opt_rebase),
 138         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 139                 N_("do not show a diffstat at the end of the merge"),
 140                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 141         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 142                 N_("show a diffstat at the end of the merge"),
 143                 PARSE_OPT_NOARG),
 144         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 145                 N_("(synonym to --stat)"),
 146                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 147         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 148                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 149                 PARSE_OPT_OPTARG),
 150         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 151                 N_("add a Signed-off-by trailer"),
 152                 PARSE_OPT_OPTARG),
 153         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 154                 N_("create a single commit instead of doing a merge"),
 155                 PARSE_OPT_NOARG),
 156         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 157                 N_("perform a commit if the merge succeeds (default)"),
 158                 PARSE_OPT_NOARG),
 159         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 160                 N_("edit message before committing"),
 161                 PARSE_OPT_NOARG),
 162         OPT_CLEANUP(&cleanup_arg),
 163         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 164                 N_("allow fast-forward"),
 165                 PARSE_OPT_NOARG),
 166         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 167                 N_("abort if fast-forward is not possible"),
 168                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 169         OPT_PASSTHRU(0, "verify", &opt_verify, NULL,
 170                 N_("control use of pre-merge-commit and commit-msg hooks"),
 171                 PARSE_OPT_NOARG),
 172         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 173                 N_("verify that the named commit has a valid GPG signature"),
 174                 PARSE_OPT_NOARG),
 175         OPT_BOOL(0, "autostash", &opt_autostash,
 176                 N_("automatically stash/stash pop before and after")),
 177         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 178                 N_("merge strategy to use"),
 179                 0),
 180         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 181                 N_("option=value"),
 182                 N_("option for selected merge strategy"),
 183                 0),
 184         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 185                 N_("GPG sign commit"),
 186                 PARSE_OPT_OPTARG),
 187         OPT_SET_INT(0, "allow-unrelated-histories",
 188                     &opt_allow_unrelated_histories,
 189                     N_("allow merging unrelated histories"), 1),
 190
 191         /* Options passed to git-fetch */
 192         OPT_GROUP(N_("Options related to fetching")),
 193         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 194                 N_("fetch from all remotes"),
 195                 PARSE_OPT_NOARG),
 196         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 197                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 198                 PARSE_OPT_NOARG),
 199         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 200                 N_("path to upload pack on remote end"),
 201                 0),
 202         OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),
 203         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 204                 N_("fetch all tags and associated objects"),
 205                 PARSE_OPT_NOARG),
 206         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 207                 N_("prune remote-tracking branches no longer on remote"),
 208                 PARSE_OPT_NOARG),
 209         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 210                 N_("number of submodules pulled in parallel"),
 211                 PARSE_OPT_OPTARG),
 212         OPT_BOOL(0, "dry-run", &opt_dry_run,
 213                 N_("dry run")),
 214         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 215                 N_("keep downloaded pack"),
 216                 PARSE_OPT_NOARG),
 217         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 218                 N_("deepen history of shallow clone"),
 219                 0),
 220         OPT_PASSTHRU_ARGV(0, "shallow-since", &opt_fetch, N_("time"),
 221                 N_("deepen history of shallow repository based on time"),
 222                 0),
 223         OPT_PASSTHRU_ARGV(0, "shallow-exclude", &opt_fetch, N_("revision"),
 224                 N_("deepen history of shallow clone, excluding rev"),
 225                 0),
 226         OPT_PASSTHRU_ARGV(0, "deepen", &opt_fetch, N_("n"),
 227                 N_("deepen history of shallow clone"),
 228                 0),
 229         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 230                 N_("convert to a complete repository"),
 231                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 232         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 233                 N_("accept refs that update .git/shallow"),
 234                 PARSE_OPT_NOARG),
 235         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 236                 N_("specify fetch refmap"),
 237                 PARSE_OPT_NONEG),
 238         OPT_PASSTHRU_ARGV('o', "server-option", &opt_fetch,
 239                 N_("server-specific"),
 240                 N_("option to transmit"),
 241                 0),
 242         OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,
 243                 N_("use IPv4 addresses only"),
 244                 PARSE_OPT_NOARG),
 245         OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 246                 N_("use IPv6 addresses only"),
 247                 PARSE_OPT_NOARG),
 248         OPT_PASSTHRU_ARGV(0, "negotiation-tip", &opt_fetch, N_("revision"),
 249                 N_("report that we have only objects reachable from this object"),
 250                 0),
 251         OPT_BOOL(0, "show-forced-updates", &opt_show_forced_updates,
 252                  N_("check for forced-updates on all updated branches")),
 253         OPT_PASSTHRU(0, "set-upstream", &set_upstream, NULL,
 254                 N_("set upstream for git pull/fetch"),
 255                 PARSE_OPT_NOARG),
 256
 257         OPT_END()
 258 };
 259
 260 /**
 261  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 262  */
 263 static void argv_push_verbosity(struct strvec *arr)
 264 {
 265         int verbosity;
 266
 267         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 268                 strvec_push(arr, "-v");
 269
 270         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 271                 strvec_push(arr, "-q");
 272 }
 273
 274 /**
 275  * Pushes "-f" switches into arr to match the opt_force level.
 276  */
 277 static void argv_push_force(struct strvec *arr)
 278 {
 279         int force = opt_force;
 280         while (force-- > 0)
 281                 strvec_push(arr, "-f");
 282 }
 283
 284 /**
 285  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 286  */
 287 static void set_reflog_message(int argc, const char **argv)
 288 {
 289         int i;
 290         struct strbuf msg = STRBUF_INIT;
 291
 292         for (i = 0; i < argc; i++) {
 293                 if (i)
 294                         strbuf_addch(&msg, ' ');
 295                 strbuf_addstr(&msg, argv[i]);
 296         }
 297
 298         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 299
 300         strbuf_release(&msg);
 301 }
 302
 303 /**
 304  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 305  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 306  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 307  * error.
 308  */
 309 static const char *config_get_ff(void)
 310 {
 311         const char *value;
 312
 313         if (git_config_get_value("pull.ff", &value))
 314                 return NULL;
 315
 316         switch (git_parse_maybe_bool(value)) {
 317         case 0:
 318                 return "--no-ff";
 319         case 1:
 320                 return "--ff";
 321         }
 322
 323         if (!strcmp(value, "only"))
 324                 return "--ff-only";
 325
 326         die(_("invalid value for '%s': '%s'"), "pull.ff", value);
 327 }
 328
 329 /**
 330  * Returns the default configured value for --rebase. It first looks for the
 331  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 332  * branch, and if HEAD is detached or the configuration key does not exist,
 333  * looks for the value of "pull.rebase". If both configuration keys do not
 334  * exist, returns REBASE_FALSE.
 335  */
 336 static enum rebase_type config_get_rebase(int *rebase_unspecified)
 337 {
 338         struct branch *curr_branch = branch_get("HEAD");
 339         const char *value;
 340
 341         if (curr_branch) {
 342                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 343
 344                 if (!git_config_get_value(key, &value)) {
 345                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 346                         free(key);
 347                         return ret;
 348                 }
 349
 350                 free(key);
 351         }
 352
 353         if (!git_config_get_value("pull.rebase", &value))
 354                 return parse_config_rebase("pull.rebase", value, 1);
 355
 356         *rebase_unspecified = 1;
 357
 358         return REBASE_FALSE;
 359 }
 360
 361 /**
 362  * Read config variables.
 363  */
 364 static int git_pull_config(const char *var, const char *value, void *cb)
 365 {
 366         if (!strcmp(var, "rebase.autostash")) {
 367                 config_autostash = git_config_bool(var, value);
 368                 return 0;
 369         } else if (!strcmp(var, "submodule.recurse")) {
 370                 recurse_submodules = git_config_bool(var, value) ?
 371                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 372                 return 0;
 373         } else if (!strcmp(var, "gpg.mintrustlevel")) {
 374                 check_trust_level = 0;
 375         }
 376
 377         return git_default_config(var, value, cb);
 378 }
 379
 380 /**
 381  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 382  * into merge_heads.
 383  */
 384 static void get_merge_heads(struct oid_array *merge_heads)
 385 {
 386         const char *filename = git_path_fetch_head(the_repository);
 387         FILE *fp;
 388         struct strbuf sb = STRBUF_INIT;
 389         struct object_id oid;
 390
 391         fp = xfopen(filename, "r");
 392         while (strbuf_getline_lf(&sb, fp) != EOF) {
 393                 const char *p;
 394                 if (parse_oid_hex(sb.buf, &oid, &p))
 395                         continue;  /* invalid line: does not start with object ID */
 396                 if (starts_with(p, "\tnot-for-merge\t"))
 397                         continue;  /* ref is not-for-merge */
 398                 oid_array_append(merge_heads, &oid);
 399         }
 400         fclose(fp);
 401         strbuf_release(&sb);
 402 }
 403
 404 /**
 405  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 406  * retrieve the name of the remote if the repository only has one remote.
 407  */
 408 static int get_only_remote(struct remote *remote, void *cb_data)
 409 {
 410         const char **remote_name = cb_data;
 411
 412         if (*remote_name)
 413                 return -1;
 414
 415         *remote_name = remote->name;
 416         return 0;
 417 }
 418
 419 /**
 420  * Dies with the appropriate reason for why there are no merge candidates:
 421  *
 422  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 423  *    up not fetching anything. This is usually because the user provided a
 424  *    wildcard refspec which had no matches on the remote end.
 425  *
 426  * 2. We fetched from a non-default remote, but didn't specify a branch to
 427  *    merge. We can't use the configured one because it applies to the default
 428  *    remote, thus the user must specify the branches to merge.
 429  *
 430  * 3. We fetched from the branch's or repo's default remote, but:
 431  *
 432  *    a. We are not on a branch, so there will never be a configured branch to
 433  *       merge with.
 434  *
 435  *    b. We are on a branch, but there is no configured branch to merge with.
 436  *
 437  * 4. We fetched from the branch's or repo's default remote, but the configured
 438  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 439  *    part of the configured fetch refspec.)
 440  */
 441 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 442 {
 443         struct branch *curr_branch = branch_get("HEAD");
 444         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 445
 446         if (*refspecs) {
 447                 if (opt_rebase)
 448                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 449                 else
 450                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 451                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 452                                         "matches on the remote end."));
 453         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 454                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 455                         "a branch. Because this is not the default configured remote\n"
 456                         "for your current branch, you must specify a branch on the command line."),
 457                         repo);
 458         } else if (!curr_branch) {
 459                 fprintf_ln(stderr, _("You are not currently on a branch."));
 460                 if (opt_rebase)
 461                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 462                 else
 463                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 464                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 465                 fprintf(stderr, "\n");
 466                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 467                 fprintf(stderr, "\n");
 468         } else if (!curr_branch->merge_nr) {
 469                 const char *remote_name = NULL;
 470
 471                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 472                         remote_name = _("<remote>");
 473
 474                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 475                 if (opt_rebase)
 476                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 477                 else
 478                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 479                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 480                 fprintf(stderr, "\n");
 481                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 482                 fprintf(stderr, "\n");
 483                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 484                 fprintf(stderr, "\n");
 485                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 486                                 remote_name, _("<branch>"), curr_branch->name);
 487         } else
 488                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 489                         "from the remote, but no such ref was fetched."),
 490                         *curr_branch->merge_name);
 491         exit(1);
 492 }
 493
 494 /**
 495  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 496  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 497  * is not provided in argv, it is set to NULL.
 498  */
 499 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 500                 const char ***refspecs)
 501 {
 502         if (argc > 0) {
 503                 *repo = *argv++;
 504                 argc--;
 505         } else
 506                 *repo = NULL;
 507         *refspecs = argv;
 508 }
 509
 510 /**
 511  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 512  * repository and refspecs to fetch, or NULL if they are not provided.
 513  */
 514 static int run_fetch(const char *repo, const char **refspecs)
 515 {
 516         struct child_process cmd = CHILD_PROCESS_INIT;
 517
 518         strvec_pushl(&cmd.args, "fetch", "--update-head-ok", NULL);
 519
 520         /* Shared options */
 521         argv_push_verbosity(&cmd.args);
 522         if (opt_progress)
 523                 strvec_push(&cmd.args, opt_progress);
 524
 525         /* Options passed to git-fetch */
 526         if (opt_all)
 527                 strvec_push(&cmd.args, opt_all);
 528         if (opt_append)
 529                 strvec_push(&cmd.args, opt_append);
 530         if (opt_upload_pack)
 531                 strvec_push(&cmd.args, opt_upload_pack);
 532         argv_push_force(&cmd.args);
 533         if (opt_tags)
 534                 strvec_push(&cmd.args, opt_tags);
 535         if (opt_prune)
 536                 strvec_push(&cmd.args, opt_prune);
 537         if (recurse_submodules_cli != RECURSE_SUBMODULES_DEFAULT)
 538                 switch (recurse_submodules_cli) {
 539                 case RECURSE_SUBMODULES_ON:
 540                         strvec_push(&cmd.args, "--recurse-submodules=on");
 541                         break;
 542                 case RECURSE_SUBMODULES_OFF:
 543                         strvec_push(&cmd.args, "--recurse-submodules=no");
 544                         break;
 545                 case RECURSE_SUBMODULES_ON_DEMAND:
 546                         strvec_push(&cmd.args, "--recurse-submodules=on-demand");
 547                         break;
 548                 default:
 549                         BUG("submodule recursion option not understood");
 550                 }
 551         if (max_children)
 552                 strvec_push(&cmd.args, max_children);
 553         if (opt_dry_run)
 554                 strvec_push(&cmd.args, "--dry-run");
 555         if (opt_keep)
 556                 strvec_push(&cmd.args, opt_keep);
 557         if (opt_depth)
 558                 strvec_push(&cmd.args, opt_depth);
 559         if (opt_unshallow)
 560                 strvec_push(&cmd.args, opt_unshallow);
 561         if (opt_update_shallow)
 562                 strvec_push(&cmd.args, opt_update_shallow);
 563         if (opt_refmap)
 564                 strvec_push(&cmd.args, opt_refmap);
 565         if (opt_ipv4)
 566                 strvec_push(&cmd.args, opt_ipv4);
 567         if (opt_ipv6)
 568                 strvec_push(&cmd.args, opt_ipv6);
 569         if (opt_show_forced_updates > 0)
 570                 strvec_push(&cmd.args, "--show-forced-updates");
 571         else if (opt_show_forced_updates == 0)
 572                 strvec_push(&cmd.args, "--no-show-forced-updates");
 573         if (set_upstream)
 574                 strvec_push(&cmd.args, set_upstream);
 575         strvec_pushv(&cmd.args, opt_fetch.v);
 576
 577         if (repo) {
 578                 strvec_push(&cmd.args, repo);
 579                 strvec_pushv(&cmd.args, refspecs);
 580         } else if (*refspecs)
 581                 BUG("refspecs without repo?");
 582         cmd.git_cmd = 1;
 583         cmd.close_object_store = 1;
 584         return run_command(&cmd);
 585 }
 586
 587 /**
 588  * "Pulls into void" by branching off merge_head.
 589  */
 590 static int pull_into_void(const struct object_id *merge_head,
 591                 const struct object_id *curr_head)
 592 {
 593         if (opt_verify_signatures) {
 594                 struct commit *commit;
 595
 596                 commit = lookup_commit(the_repository, merge_head);
 597                 if (!commit)
 598                         die(_("unable to access commit %s"),
 599                             oid_to_hex(merge_head));
 600
 601                 verify_merge_signature(commit, opt_verbosity,
 602                                        check_trust_level);
 603         }
 604
 605         /*
 606          * Two-way merge: we treat the index as based on an empty tree,
 607          * and try to fast-forward to HEAD. This ensures we will not lose
 608          * index/worktree changes that the user already made on the unborn
 609          * branch.
 610          */
 611         if (checkout_fast_forward(the_repository,
 612                                   the_hash_algo->empty_tree,
 613                                   merge_head, 0))
 614                 return 1;
 615
 616         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 617                 return 1;
 618
 619         return 0;
 620 }
 621
 622 static int rebase_submodules(void)
 623 {
 624         struct child_process cp = CHILD_PROCESS_INIT;
 625
 626         cp.git_cmd = 1;
 627         cp.no_stdin = 1;
 628         strvec_pushl(&cp.args, "submodule", "update",
 629                      "--recursive", "--rebase", NULL);
 630         argv_push_verbosity(&cp.args);
 631
 632         return run_command(&cp);
 633 }
 634
 635 static int update_submodules(void)
 636 {
 637         struct child_process cp = CHILD_PROCESS_INIT;
 638
 639         cp.git_cmd = 1;
 640         cp.no_stdin = 1;
 641         strvec_pushl(&cp.args, "submodule", "update",
 642                      "--recursive", "--checkout", NULL);
 643         argv_push_verbosity(&cp.args);
 644
 645         return run_command(&cp);
 646 }
 647
 648 /**
 649  * Runs git-merge, returning its exit status.
 650  */
 651 static int run_merge(void)
 652 {
 653         struct child_process cmd = CHILD_PROCESS_INIT;
 654
 655         strvec_pushl(&cmd.args, "merge", NULL);
 656
 657         /* Shared options */
 658         argv_push_verbosity(&cmd.args);
 659         if (opt_progress)
 660                 strvec_push(&cmd.args, opt_progress);
 661
 662         /* Options passed to git-merge */
 663         if (opt_diffstat)
 664                 strvec_push(&cmd.args, opt_diffstat);
 665         if (opt_log)
 666                 strvec_push(&cmd.args, opt_log);
 667         if (opt_signoff)
 668                 strvec_push(&cmd.args, opt_signoff);
 669         if (opt_squash)
 670                 strvec_push(&cmd.args, opt_squash);
 671         if (opt_commit)
 672                 strvec_push(&cmd.args, opt_commit);
 673         if (opt_edit)
 674                 strvec_push(&cmd.args, opt_edit);
 675         if (cleanup_arg)
 676                 strvec_pushf(&cmd.args, "--cleanup=%s", cleanup_arg);
 677         if (opt_ff)
 678                 strvec_push(&cmd.args, opt_ff);
 679         if (opt_verify)
 680                 strvec_push(&cmd.args, opt_verify);
 681         if (opt_verify_signatures)
 682                 strvec_push(&cmd.args, opt_verify_signatures);
 683         strvec_pushv(&cmd.args, opt_strategies.v);
 684         strvec_pushv(&cmd.args, opt_strategy_opts.v);
 685         if (opt_gpg_sign)
 686                 strvec_push(&cmd.args, opt_gpg_sign);
 687         if (opt_autostash == 0)
 688                 strvec_push(&cmd.args, "--no-autostash");
 689         else if (opt_autostash == 1)
 690                 strvec_push(&cmd.args, "--autostash");
 691         if (opt_allow_unrelated_histories > 0)
 692                 strvec_push(&cmd.args, "--allow-unrelated-histories");
 693
 694         strvec_push(&cmd.args, "FETCH_HEAD");
 695         cmd.git_cmd = 1;
 696         return run_command(&cmd);
 697 }
 698
 699 /**
 700  * Returns remote's upstream branch for the current branch. If remote is NULL,
 701  * the current branch's configured default remote is used. Returns NULL if
 702  * `remote` does not name a valid remote, HEAD does not point to a branch,
 703  * remote is not the branch's configured remote or the branch does not have any
 704  * configured upstream branch.
 705  */
 706 static const char *get_upstream_branch(const char *remote)
 707 {
 708         struct remote *rm;
 709         struct branch *curr_branch;
 710         const char *curr_branch_remote;
 711
 712         rm = remote_get(remote);
 713         if (!rm)
 714                 return NULL;
 715
 716         curr_branch = branch_get("HEAD");
 717         if (!curr_branch)
 718                 return NULL;
 719
 720         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 721         assert(curr_branch_remote);
 722
 723         if (strcmp(curr_branch_remote, rm->name))
 724                 return NULL;
 725
 726         return branch_get_upstream(curr_branch, NULL);
 727 }
 728
 729 /**
 730  * Derives the remote-tracking branch from the remote and refspec.
 731  *
 732  * FIXME: The current implementation assumes the default mapping of
 733  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 734  */
 735 static const char *get_tracking_branch(const char *remote, const char *refspec)
 736 {
 737         struct refspec_item spec;
 738         const char *spec_src;
 739         const char *merge_branch;
 740
 741         refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);
 742         spec_src = spec.src;
 743         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 744                 spec_src = "HEAD";
 745         else if (skip_prefix(spec_src, "heads/", &spec_src))
 746                 ;
 747         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 748                 ;
 749         else if (starts_with(spec_src, "refs/") ||
 750                 starts_with(spec_src, "tags/") ||
 751                 starts_with(spec_src, "remotes/"))
 752                 spec_src = "";
 753
 754         if (*spec_src) {
 755                 if (!strcmp(remote, "."))
 756                         merge_branch = mkpath("refs/heads/%s", spec_src);
 757                 else
 758                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 759         } else
 760                 merge_branch = NULL;
 761
 762         refspec_item_clear(&spec);
 763         return merge_branch;
 764 }
 765
 766 /**
 767  * Given the repo and refspecs, sets fork_point to the point at which the
 768  * current branch forked from its remote-tracking branch. Returns 0 on success,
 769  * -1 on failure.
 770  */
 771 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 772                 const char *refspec)
 773 {
 774         int ret;
 775         struct branch *curr_branch;
 776         const char *remote_branch;
 777         struct child_process cp = CHILD_PROCESS_INIT;
 778         struct strbuf sb = STRBUF_INIT;
 779
 780         curr_branch = branch_get("HEAD");
 781         if (!curr_branch)
 782                 return -1;
 783
 784         if (refspec)
 785                 remote_branch = get_tracking_branch(repo, refspec);
 786         else
 787                 remote_branch = get_upstream_branch(repo);
 788
 789         if (!remote_branch)
 790                 return -1;
 791
 792         strvec_pushl(&cp.args, "merge-base", "--fork-point",
 793                      remote_branch, curr_branch->name, NULL);
 794         cp.no_stdin = 1;
 795         cp.no_stderr = 1;
 796         cp.git_cmd = 1;
 797
 798         ret = capture_command(&cp, &sb, GIT_MAX_HEXSZ);
 799         if (ret)
 800                 goto cleanup;
 801
 802         ret = get_oid_hex(sb.buf, fork_point);
 803         if (ret)
 804                 goto cleanup;
 805
 806 cleanup:
 807         strbuf_release(&sb);
 808         return ret ? -1 : 0;
 809 }
 810
 811 /**
 812  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 813  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 814  */
 815 static int get_octopus_merge_base(struct object_id *merge_base,
 816                 const struct object_id *curr_head,
 817                 const struct object_id *merge_head,
 818                 const struct object_id *fork_point)
 819 {
 820         struct commit_list *revs = NULL, *result;
 821
 822         commit_list_insert(lookup_commit_reference(the_repository, curr_head),
 823                            &revs);
 824         commit_list_insert(lookup_commit_reference(the_repository, merge_head),
 825                            &revs);
 826         if (!is_null_oid(fork_point))
 827                 commit_list_insert(lookup_commit_reference(the_repository, fork_point),
 828                                    &revs);
 829
 830         result = get_octopus_merge_bases(revs);
 831         free_commit_list(revs);
 832         reduce_heads_replace(&result);
 833
 834         if (!result)
 835                 return 1;
 836
 837         oidcpy(merge_base, &result->item->object.oid);
 838         free_commit_list(result);
 839         return 0;
 840 }
 841
 842 /**
 843  * Given the current HEAD oid, the merge head returned from git-fetch and the
 844  * fork point calculated by get_rebase_fork_point(), compute the <newbase> and
 845  * <upstream> arguments to use for the upcoming git-rebase invocation.
 846  */
 847 static int get_rebase_newbase_and_upstream(struct object_id *newbase,
 848                 struct object_id *upstream,
 849                 const struct object_id *curr_head,
 850                 const struct object_id *merge_head,
 851                 const struct object_id *fork_point)
 852 {
 853         struct object_id oct_merge_base;
 854
 855         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 856                 if (!is_null_oid(fork_point) && oideq(&oct_merge_base, fork_point))
 857                         fork_point = NULL;
 858
 859         if (fork_point && !is_null_oid(fork_point))
 860                 oidcpy(upstream, fork_point);
 861         else
 862                 oidcpy(upstream, merge_head);
 863
 864         oidcpy(newbase, merge_head);
 865
 866         return 0;
 867 }
 868
 869 /**
 870  * Given the <newbase> and <upstream> calculated by
 871  * get_rebase_newbase_and_upstream(), runs git-rebase with the
 872  * appropriate arguments and returns its exit status.
 873  */
 874 static int run_rebase(const struct object_id *newbase,
 875                 const struct object_id *upstream)
 876 {
 877         struct child_process cmd = CHILD_PROCESS_INIT;
 878
 879         strvec_push(&cmd.args, "rebase");
 880
 881         /* Shared options */
 882         argv_push_verbosity(&cmd.args);
 883
 884         /* Options passed to git-rebase */
 885         if (opt_rebase == REBASE_MERGES)
 886                 strvec_push(&cmd.args, "--rebase-merges");
 887         else if (opt_rebase == REBASE_INTERACTIVE)
 888                 strvec_push(&cmd.args, "--interactive");
 889         if (opt_diffstat)
 890                 strvec_push(&cmd.args, opt_diffstat);
 891         strvec_pushv(&cmd.args, opt_strategies.v);
 892         strvec_pushv(&cmd.args, opt_strategy_opts.v);
 893         if (opt_gpg_sign)
 894                 strvec_push(&cmd.args, opt_gpg_sign);
 895         if (opt_signoff)
 896                 strvec_push(&cmd.args, opt_signoff);
 897         if (opt_autostash == 0)
 898                 strvec_push(&cmd.args, "--no-autostash");
 899         else if (opt_autostash == 1)
 900                 strvec_push(&cmd.args, "--autostash");
 901         if (opt_verify_signatures &&
 902             !strcmp(opt_verify_signatures, "--verify-signatures"))
 903                 warning(_("ignoring --verify-signatures for rebase"));
 904
 905         strvec_push(&cmd.args, "--onto");
 906         strvec_push(&cmd.args, oid_to_hex(newbase));
 907
 908         strvec_push(&cmd.args, oid_to_hex(upstream));
 909
 910         cmd.git_cmd = 1;
 911         return run_command(&cmd);
 912 }
 913
 914 static int get_can_ff(struct object_id *orig_head,
 915                       struct oid_array *merge_heads)
 916 {
 917         int ret;
 918         struct commit_list *list = NULL;
 919         struct commit *merge_head, *head;
 920         struct object_id *orig_merge_head;
 921
 922         if (merge_heads->nr > 1)
 923                 return 0;
 924
 925         orig_merge_head = &merge_heads->oid[0];
 926         head = lookup_commit_reference(the_repository, orig_head);
 927         commit_list_insert(head, &list);
 928         merge_head = lookup_commit_reference(the_repository, orig_merge_head);
 929         ret = repo_is_descendant_of(the_repository, merge_head, list);
 930         free_commit_list(list);
 931         return ret;
 932 }
 933
 934 /*
 935  * Is orig_head a descendant of _all_ merge_heads?
 936  * Unfortunately is_descendant_of() cannot be used as it asks
 937  * if orig_head is a descendant of at least one of them.
 938  */
 939 static int already_up_to_date(struct object_id *orig_head,
 940                               struct oid_array *merge_heads)
 941 {
 942         int i;
 943         struct commit *ours;
 944
 945         ours = lookup_commit_reference(the_repository, orig_head);
 946         for (i = 0; i < merge_heads->nr; i++) {
 947                 struct commit_list *list = NULL;
 948                 struct commit *theirs;
 949                 int ok;
 950
 951                 theirs = lookup_commit_reference(the_repository, &merge_heads->oid[i]);
 952                 commit_list_insert(theirs, &list);
 953                 ok = repo_is_descendant_of(the_repository, ours, list);
 954                 free_commit_list(list);
 955                 if (!ok)
 956                         return 0;
 957         }
 958         return 1;
 959 }
 960
 961 static void show_advice_pull_non_ff(void)
 962 {
 963         advise(_("You have divergent branches and need to specify how to reconcile them.\n"
 964                  "You can do so by running one of the following commands sometime before\n"
 965                  "your next pull:\n"
 966                  "\n"
 967                  "  git config pull.rebase false  # merge\n"
 968                  "  git config pull.rebase true   # rebase\n"
 969                  "  git config pull.ff only       # fast-forward only\n"
 970                  "\n"
 971                  "You can replace \"git config\" with \"git config --global\" to set a default\n"
 972                  "preference for all repositories. You can also pass --rebase, --no-rebase,\n"
 973                  "or --ff-only on the command line to override the configured default per\n"
 974                  "invocation.\n"));
 975 }
 976
 977 int cmd_pull(int argc, const char **argv, const char *prefix)
 978 {
 979         const char *repo, **refspecs;
 980         struct oid_array merge_heads = OID_ARRAY_INIT;
 981         struct object_id orig_head, curr_head;
 982         struct object_id rebase_fork_point;
 983         int rebase_unspecified = 0;
 984         int can_ff;
 985         int divergent;
 986         int ret;
 987
 988         if (!getenv("GIT_REFLOG_ACTION"))
 989                 set_reflog_message(argc, argv);
 990
 991         git_config(git_pull_config, NULL);
 992         if (the_repository->gitdir) {
 993                 prepare_repo_settings(the_repository);
 994                 the_repository->settings.command_requires_full_index = 0;
 995         }
 996
 997         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 998
 999         if (recurse_submodules_cli != RECURSE_SUBMODULES_DEFAULT)
1000                 recurse_submodules = recurse_submodules_cli;
1001
1002         if (cleanup_arg)
1003                 /*
1004                  * this only checks the validity of cleanup_arg; we don't need
1005                  * a valid value for use_editor
1006                  */
1007                 get_cleanup_mode(cleanup_arg, 0);
1008
1009         parse_repo_refspecs(argc, argv, &repo, &refspecs);
1010
1011         if (!opt_ff) {
1012                 opt_ff = xstrdup_or_null(config_get_ff());
1013                 /*
1014                  * A subtle point: opt_ff was set on the line above via
1015                  * reading from config.  opt_rebase, in contrast, is set
1016                  * before this point via command line options.  The setting
1017                  * of opt_rebase via reading from config (using
1018                  * config_get_rebase()) does not happen until later.  We
1019                  * are relying on the next if-condition happening before
1020                  * the config_get_rebase() call so that an explicit
1021                  * "--rebase" can override a config setting of
1022                  * pull.ff=only.
1023                  */
1024                 if (opt_rebase >= 0 && opt_ff && !strcmp(opt_ff, "--ff-only"))
1025                         opt_ff = "--ff";
1026         }
1027
1028         if (opt_rebase < 0)
1029                 opt_rebase = config_get_rebase(&rebase_unspecified);
1030
1031         if (repo_read_index_unmerged(the_repository))
1032                 die_resolve_conflict("pull");
1033
1034         if (file_exists(git_path_merge_head(the_repository)))
1035                 die_conclude_merge();
1036
1037         if (repo_get_oid(the_repository, "HEAD", &orig_head))
1038                 oidclr(&orig_head);
1039
1040         if (opt_rebase) {
1041                 if (opt_autostash == -1)
1042                         opt_autostash = config_autostash;
1043
1044                 if (is_null_oid(&orig_head) && !is_index_unborn(&the_index))
1045                         die(_("Updating an unborn branch with changes added to the index."));
1046
1047                 if (!opt_autostash)
1048                         require_clean_work_tree(the_repository,
1049                                 N_("pull with rebase"),
1050                                 _("please commit or stash them."), 1, 0);
1051
1052                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
1053                         oidclr(&rebase_fork_point);
1054         }
1055
1056         if (run_fetch(repo, refspecs))
1057                 return 1;
1058
1059         if (opt_dry_run)
1060                 return 0;
1061
1062         if (repo_get_oid(the_repository, "HEAD", &curr_head))
1063                 oidclr(&curr_head);
1064
1065         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
1066                         !oideq(&orig_head, &curr_head)) {
1067                 /*
1068                  * The fetch involved updating the current branch.
1069                  *
1070                  * The working tree and the index file are still based on
1071                  * orig_head commit, but we are merging into curr_head.
1072                  * Update the working tree to match curr_head.
1073                  */
1074
1075                 warning(_("fetch updated the current branch head.\n"
1076                         "fast-forwarding your working tree from\n"
1077                         "commit %s."), oid_to_hex(&orig_head));
1078
1079                 if (checkout_fast_forward(the_repository, &orig_head,
1080                                           &curr_head, 0))
1081                         die(_("Cannot fast-forward your working tree.\n"
1082                                 "After making sure that you saved anything precious from\n"
1083                                 "$ git diff %s\n"
1084                                 "output, run\n"
1085                                 "$ git reset --hard\n"
1086                                 "to recover."), oid_to_hex(&orig_head));
1087         }
1088
1089         get_merge_heads(&merge_heads);
1090
1091         if (!merge_heads.nr)
1092                 die_no_merge_candidates(repo, refspecs);
1093
1094         if (is_null_oid(&orig_head)) {
1095                 if (merge_heads.nr > 1)
1096                         die(_("Cannot merge multiple branches into empty head."));
1097                 ret = pull_into_void(merge_heads.oid, &curr_head);
1098                 goto cleanup;
1099         }
1100         if (merge_heads.nr > 1) {
1101                 if (opt_rebase)
1102                         die(_("Cannot rebase onto multiple branches."));
1103                 if (opt_ff && !strcmp(opt_ff, "--ff-only"))
1104                         die(_("Cannot fast-forward to multiple branches."));
1105         }
1106
1107         can_ff = get_can_ff(&orig_head, &merge_heads);
1108         divergent = !can_ff && !already_up_to_date(&orig_head, &merge_heads);
1109
1110         /* ff-only takes precedence over rebase */
1111         if (opt_ff && !strcmp(opt_ff, "--ff-only")) {
1112                 if (divergent)
1113                         die_ff_impossible();
1114                 opt_rebase = REBASE_FALSE;
1115         }
1116         /* If no action specified and we can't fast forward, then warn. */
1117         if (!opt_ff && rebase_unspecified && divergent) {
1118                 show_advice_pull_non_ff();
1119                 die(_("Need to specify how to reconcile divergent branches."));
1120         }
1121
1122         if (opt_rebase) {
1123                 struct object_id newbase;
1124                 struct object_id upstream;
1125                 get_rebase_newbase_and_upstream(&newbase, &upstream, &curr_head,
1126                                                 merge_heads.oid, &rebase_fork_point);
1127
1128                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
1129                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
1130                     submodule_touches_in_range(the_repository, &upstream, &curr_head))
1131                         die(_("cannot rebase with locally recorded submodule modifications"));
1132
1133                 if (can_ff) {
1134                         /* we can fast-forward this without invoking rebase */
1135                         opt_ff = "--ff-only";
1136                         ret = run_merge();
1137                 } else {
1138                         ret = run_rebase(&newbase, &upstream);
1139                 }
1140
1141                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1142                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1143                         ret = rebase_submodules();
1144
1145                 goto cleanup;
1146         } else {
1147                 ret = run_merge();
1148                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1149                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1150                         ret = update_submodules();
1151                 goto cleanup;
1152         }
1153
1154 cleanup:
1155         oid_array_clear(&merge_heads);
1156         return ret;
1157 }